What were Theodore Roosevelt's main contributions to American history Essay

What were Theodore Roosevelt's main contributions to American history - Essay Example He made the title of the President, instead of the political parties or the Congress, the epicenter of American government and legislation. Roosevelt also transformed the governments relationship to large industries and businesses. Preceding his presidency, the administration had normally given the giants of business and commerce complete freedom and authority to achieve their objectives. The President, however, considered that the government should have the right and the duty to control and regulate large industries so that its engagements did not negatively disturb the common public. In addition, Roosevelt transformed foreign affairs, deeming that the nation had a global duty and that a solid foreign policy helped the countrys concerns. He decided to get involved in Latin America with little reluctance. He also worked with the Congress to reinforce the U.S. Navy, which he knew would discourage possible enemies from aiming the country. He spent time in discussing peace agreements, exerting to balance power in the world. He was accountable for instigating several antitrust laws, and he effectively persuaded the US offer to construct the Panama Canal. He also negotiated the termination of the Russo-Japanese War in 1905. The most well liked President up to his time, Teddy Roosevelt used his fervor to shape concerns, and to affect opinions and in the process, transformed the executive office

René Descartes Essay Example for Free

Renà © Descartes Essay Philosophy begins as an art of wondering. This art of wondering, leads man into asking a number of questions about himself and the world around him. Variations in philosophical thoughts as result questions posed by man, help in modification of philosophy. The purpose of this essay therefore, is to do a comparative analysis of Sophie’s World by Josteen Gaarder with three philosophical texts: George Berkeley’s Treatise on Human Knowledge, John Locke’s Essay on Human Understanding and Rene Descartes’ Passions of the Soul. We shall also show the roles of authors and texts in Philosophy. TREATISE ON HUMAN KNOWLEDGE VERSUS SOPHIE’S WORLD One of the outstanding efforts of Berkeley in this work was to show that the world exists as it does because of the ideas perceived by the mind of God and as such, existence of things depends on their perception through the senses. Likewise in Sophie’s World, Aristotle through his belief showed a similarity with Berkeley’s stance in this text Treatise of Human Understanding. For Aristotle, highest degree of reality is what we perceive with our senses. Berkeley also said that existence is the state of being perceived by a perceiver, but on the contrary, Descartes in Sophie’s World believed that he exists because he thinks. It furthermore means that his existence depends on his ability to think. He used such words like cogito ergo sum (latin) and je pense, donc je suis (French) all meaning `I think therefore I am` to illuminate his thesis on this. Plato while stressing the sovereignty of reason in Sophie’s World said that the reason can only give us the true reality of things and as such contradicted the empiricist approach of Berkeley. ESSAY ON HUMAN UNDERSTANDING VERSUS SOPHIE’S WORLD John Locke illuminated in this work that idea is derived from experience of sensation or reflection, just like it reflected in Sophie’s World in which his fellow empiricists likewise stressed the inevitability of experience as the source of true knowledge. David Hume in particular established that man has two types of perceptions, namely: impressions and ideas. By `impressions` he means the external sensations of reality. By `ideas` he means the recollections of such impressions. Aristotle the trail blazer of empiricism, in alignment with the empiricists believed our reason to be completely empty until we have sensed something. John Locke in this book made an attempt to refute the notion of `innate ideas` by proving that it does not exist, whereas in Sophie’s World, philosopher like Plato believed in an innate idea, an external world of ideas outside of the natural world. Descartes even believed that the idea of God is innate. PASSIONS OF THE SOUL VERSUS SOPHIE’S WORLD Descartes defined passions of the soul as a mental state or thought that arises as a direct result of brain activity and such passions can move us to action. He also suggested that one needs to learn to control one’s passions, for they can move one to perform vicious acts. Benedict Spinosa in Sophie’s World, suggested that we must free ourselves from our feelings and passions only then shall we find happiness. Conversely, also in Sophie’s World, the Epicureans through the teachings of Aristippus believed that the aim of life is to attain the highest possible pleasure or passions and by so doing, they contradict Descartes belief. AN EYE ON THE ROLES OF AUTHORS AND TEXTS IN PHILOSOPHY Authors in philosophy play incredible roles in modification of philosophy through their texts. There various attempts to answer the underlying questions of nature and man have led to the developments of dialectical methods like thesis, antithesis and synthesis used in philosophy today. An eye on the three authors and philosophers: Descartes, Berkeley and Locke whose works where compared with Sophie’s World above showed the vital role they played in philosophy. While Descartes was a rationalist, Berkeley and Locke were empiricists, but through their texts, they contributed in `epistemology` or theory of knowledge. CONCLUSION Having done these comparisons, we can see the successful deduction of similarities and differences between the Sophie’s World and three aforementioned philosophical texts. I attest that Sophie’s World is necessary philosophical paraphernalia needed by a neophyte in Philosophy as seen from its versatility in the course of this comparison done, and also how it covered aspects of history of Philosophy in such a sublime manner. POPE JOHN PAUL II MAJOR SEMINARY OKPUNO, AWKA NAME: UMENABA BENJAMIN C COURSE: INTRODUCTION TO PHILOSOPHY COURSE CODE: PHIL 101 REG NO: PJPS/NAU/013/O69 LECTURER: REV. FR DR. AUGUSTINE OBUROTA TOPIC: A COMPARATIVE ANALYSIS OF SOPHIE’S WORLD WITH THREE PHILOSOPHY TEXTS WITH AN EYE ON ROLES OF AUTHORS AND TEXTS IN PHILOSOPHY DATE: 28TH NOVEMBER, 2012 OUTLINES INTRODUCTION TREATISE ON HUMAN KNOWLEDGE VERSUS SOPHIE’S WORLD ESSAY ON HUMAN UNDERSTANDING VERSUS SOPHIE’S WORLD PASSIONS OF THE SOUL VERSUS SOPHIE’S WORLD AN EYE ON THE ROLES OF AUTHORS AND TEXTS IN PHILOSOPHY CONCLUSION.

Teenage Humor :: essays research papers

  Ã‚  Ã‚  Ã‚  Ã‚  Teenage humour is unlike adult humour. Teenagers laugh at â€Å"Toilet† humour while adults laugh at â€Å"Civilized† humour. Therefore considering that teenagers laugh at the opposite of what adults do, we need to define the reasons why teenage and adult humour is so different.   Ã‚  Ã‚  Ã‚  Ã‚  I believe that teenage humour is sex oriented. I took a survey of ten teenagers to see what they believed was humorous. Trisha Lindsay believes that embarrassing moments are hilarious. Dustin Lockhart, Nadia Korfitsen, David Webster, Rick Fawcus, Kristi Webster, and myself believe that sex or sexual suggestions are humorous. Renita Manj and Ashlee Green believe that people who act idiotically or hurt themselves on a regular basis are hilarious. I believe that from this survey I have proved to you that most teenagers believe that sexual suggestions are the most funny in our generation.   Ã‚  Ã‚  Ã‚  Ã‚  The television programs that most teenagers watch are The Simpson’s, Friends, and That 70’s show. The Simpson’s is a program that is aired on Fox and it is a cartoon. The Simpson’s is about a middle-aged man named Homer. He is a dumb-founded idiot that works at a nuclear power plant. We laugh at him because he makes so many mistakes even if they are the easiest task. Bart is a ten year old kid who gets into trouble more then once a day. He gets into trouble at school and even when he is walking down the street to go home. He is like an average ten year old kid that likes to get into mischief. Bart is just a trouble maker that doesn‘t know when to behave himself. His sister Lisa is a straight â€Å"A† student that is on the Honour Roll, and plays the saxophone in the school Band. Every little girl would like to be Lisa because she is very mature for an eight year old. Marge is the mother of both Bart and Lisa. She is a homem aker and isn’t very funny. Bart and Homer are the prime targets for funniness in this series.   Ã‚  Ã‚  Ã‚  Ã‚  That 70’s show is the second example of a television show that teenagers find amusing. Adults find this amusing as well because they can relate to the subject. This show is about the 70’s obviously. It is how our parents use to be. I believe this is one reason why teenagers find this television show amusing. The cast of the 70’s show involves Kitty and Red who are Eric’s parents.

Happiness Levels and Income Levels

Ariella Dayan (326883881) Quantitative Research Methods- Shani Greenspan November 25, 2012 The Correlation of Income Level and Happiness Level This study will investigate the relationship between income and happiness. A very popular question in today’s society is whether money can buy happiness. Happiness has been shown to be related to many things. It is found to be related to social class, success, power, health, valued belongings, religious beliefs, companionship, being employed in a secure job, having a full social life, and more or less accumulation of money.Research shows that money does not buy happiness but it comes indirectly from the higher rank in society that money brings. â€Å"The rank-income hypothesis† was tested and found that the ranked position of an individual’s income predicts general life satisfaction. Once someone has a large amount of money they may become part of a different social group which brings more confidence and satisfaction. A pe rsons’ satisfaction and self-esteem will increase if his social rank increases or if those who once had the same social rank him decreases.People naturally feel better and more satisfied if they are better than others. (Boyce, C. et al. 2010) People dedicate so much energy in trying to make more money, when having more money does not make them that much happier. People may be happy with their current level of wealth and stop trying to accumulate more if not for the urge humans have to compare themselves with others in every way possible: attractiveness, intelligence, height, weight, and crucially, financial success. The writer H. L. Mencken said, â€Å"A wealthy man is one who earns $100 a year more than his wife's sister's husband. This frustration of seeing someone â€Å"better† than you becomes a huge motivator when it comes to making more money. People are very concerned with the phenomenon of â€Å"Keeping up with the Joneses. † Hollywood made a movie abou t a wealthy and good looking American family and the affects they have on the people living in their neighborhood. The movie presents us with â€Å"conspicuous consumption† and comparing each other’s expensive possessions and social rank. People will always to try to move ahead of as many of their friends as possible in order to† improve† themselves.People try to enhance their social hierarchy by making unnecessary investments in order to satisfy their preoccupation with their relative social standing which the socio- economic class isn’t Ariella Dayan (326883881) Quantitative Research Methods- Shani Greenspan November 25, 2012 able to do, although we can see this form of competitiveness in the socio-economic class as well. A recent study shows that a group of people in the US who are most opposed to an increase in the minimum wage are those who make just above the minimum wage.Because if the minimum wage increases, these people will now be in  "last place†, along with all the people whom they used to feel superior to. (Norton, M. 2012) Another reason why money translated to happiness often is because money has a property that many other things that matter in life do not. Money is something that can be counted. When people reflect on whether they are better off this year than last, they cannot always give an exact answer. A person cannot say that their life is 32 per cent more meaningful. This is not a calculation we are accustomed to making. Salary, on the other hand, is measurable.If a person is making a better salary they will think that they are doing better in their life. This also may explain why people are always buying larger houses and larger televisions. As people become richer, they quickly grow accustomed to bigger houses, flashier cars, and designer garments, but their possessions don't actually make them much happier. (Norton, M. 2012) Studies show that even lottery winners, after an initial period of a djustment, don't become much happier. The reason for this is because the faster people try to get ahead, the quicker they end up back where they started.Another research conducted in the University of British Columbia in Vancouver, asked people to predict how happy they would be if their annual income was anywhere from $5000 up to $1 million. After this, the people were asked how much money they really earned and how happy they were with their lives. It was found that people generally overestimated the impact of money on happiness. Those who earned $25,000 a year predicted that their happiness would double if they made $55,000. But when we measured the happiness of people at these two levels of income by having them rate their satisfaction with life on a cale from 1 to 10, it was found that the wealthier group was only 9 per cent happier. On the other hand, people who make very little money do become significantly happier when they earn more. But a large survey of people in the US s howed that the impact of additional income on happiness Ariella Dayan (326883881) Quantitative Research Methods- Shani Greenspan November 25, 2012 tends to fade around an annual salary of $75,000. There is no data suggesting that making more money makes people less happy but it does stop making them much happier. (Cassidy, J. 008) What people can do in order to gain happiness in a better manner is by doing something unusual with it or â€Å"giving it away†. It turns out that spending money on yourself does not make you any happier, but spending on others does. Donating to charity or buying coffee for a friend is an efficient way of turning cash into happiness. (Cassidy, J. 2008) A worldwide survey was created in 2006 by Gallup. He asked people to imagine themselves on a ladder with steps numbered from zero to 10, with the bottom of the ladder representing â€Å"the worst possible life for you† and the top representing â€Å"the best possible life for you. The responde nts were then asked to say which step they were standing on. If you instruct people to think about the best possible and worst possible lives they could be living, you are surely inviting them to compare their living standards with those of people elsewhere. This methodological quirk alone could easily explain why residents of poor countries report low scores and residents of rich countries report high ones, and it wouldn't have anything to do with money making people happier. ( Buchanan, M. 2009) The conclusion is that happiness and money do correlate but only to a certain extent.People are more concerned with their social class, â€Å"getting ahead† and where money can get them in life than the actual amount of money. This topic should continue to be researched in order to find if in today generation a person can actually be happy with what he or she has without comparing themselves to their peers and surroundings. Ariella Dayan (326883881) Quantitative Research Methods- Sh ani Greenspan November 25, 2012 References Boyce, C. Christopher J. 1 Brown, Gordon D. A. 2 Moore, Simon C. (2010). Money and Happiness: Rank of Income, Not Income, Affects Life Satisfaction.Psychological Science, Vol. 21 Issue 4, p471-475, 5p http://web. ebscohost. com. ezprimo1. idc. ac. il/ehost/detail? sid=daeaee80-c08b-433b-84c3-094cde8b9e7c%40sessionmgr10;vid=1;hid=13;bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=a9h;AN=62587809 Norton, M. I. (2012). The more money, the merrier? New Scientist, 215, 40-41. http://web. ebscohost. com. ezprimo1. idc. ac. il/ehost/detail? sid=86a4832c-2e11-4055-a8c7-ba24949afac4%40sessionmgr11;vid=1;hid=13;bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=a9h;AN=78189804 Cassidy,J. 2008) Happinness is†¦. Conde Nast Portfolio; Vol. 2 Issue 7, p36-36, 1p http://web. ebscohost. com. ezprimo1. idc. ac. il/ehost/detail? sid=ab06d568-bb15-434e-b357-a6330d98f4a5%40sessionmgr4;vid=1;hid=13;bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=bth;AN=38013329 Buc hanan, M. (2009) Money in Mind. New Scientist Vol. 201 p26-30, 5p http://web. ebscohost. com. ezprimo1. idc. ac. il/ehost/detail? sid=81a76105-82e3-428d-8827-47f8203d01bc%40sessionmgr111;vid=1;hid=126;bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=a9h;AN=37249111

Nostra Aetate

Years ago, a man was crucified for saying he was God’s Son. His name was Jesus Christ. Those who followed his teachings were named Christians; and Christians soon resented Jews for their sinful act. This tension between Christians and Jews lead to increasing hatred for one another. Not too long ago, anti-Semitism was common. Anti-Semitism led to the death of an entire population during the Holocaust. Luckily, the church has taken measures to rectify this anti-semitism with the publication of Nostra Aetate.In 1965, the Vatican II Council completely transformed the church’s policies and theology with this document. Nostra Aetate signifies â€Å"In Our Time. † Indeed, in our time, the ill sentiments towards Jews have changed tremendously. Nostra Aetate is a unifying document that has not only led to peaceful coexistence of the Catholic and Judaic faith but also understanding of many other faiths. Ultimately, it has enabled the education of Catholicism in universitie s, as well as in organizations. From the beginning of time, men have had continuous arguments over religion.Religion has been the greatest source of disagreement between cultures. Even the foundation of America was built on religious freedom, as Puritans from Great Britain came to the United States to practice their religion freely. The biggest religious disagreement, however, has been between the Catholics and the Jews. Section four of Nostra Aetate is the most important section of the entire document. It reaffirms the religious bond shared by Jews and Catholics, talks about the eternal covenant between God and the People of Israel, and disproves the church’s desire to baptize Jews..This document states, â€Å"Humanity forms but one community. This is so because all stem from the one stock which God created to people the entire earth (see Acts 17:26), and also because all share a common destiny, namely God. † Nostra Aetate acknowledges that the religions of Judaism an d Christianity believe in a sole higher being, God, which unifies them. Nostra Aetate made it possible for Catholics and Jews to coexist, and promoted the acceptance of each other’s faith. There is a sense of unity that this document possesses. It promotes dialogue with all other world religions.The Catholic Church took a stand in writing Nostra Aetate, and urged, â€Å"its sons and daughters to enter with prudence and charity into discussion and collaboration with members of other religions. † Moreover, Nostra Aetate is significant to theology because it has led to the increasing teachings of Catholicism worldwide. If applied, to this course, for example, the title of this course is the Religious Quest. Quest is defined as â€Å"an act or instance of seeking. † In a way, through Nostra Aetate, the Catholic Church was searching for understanding and resolution.At Boston College, one of the course requirements is theology. A reason for this may be due to Nostra A etate; it has made understanding other religions a priority to many institutions all over the world. Understanding each other’s religions could dissipate many of the foolish arguments that occur daily. The most misunderstood religious group at this moment is Islam. At Boston College, however, we can take a theology class focused on Islam, or Africism or any religion. We are given the chance to go on a â€Å"quest,† and to learn about any religion we want.A big reason for this is due in large part to Nostra Aetate. Nostra Aetate in that sense brings everyone together. Nostra Aetate made religious awareness more accessible, as various committees were created such as Nostra Aetate foundation, founded in 1990. Its purpose is described as â€Å"The purpose of the chair is to promote the understanding of religious, ethical and cultural values in national societies and in international relations, especially transatlantic relations. † Furthermore, Nostra Aetate also all owed the creation of a committee, named a Muslim-Catholic Liason Committee.This committee promotes the communication between Muslims and Catholic, and meets once a year to study together. They pick a theme from the point of view of the two religions, and â€Å"discuss the current situation of relations between Christians and Muslims. † They also try to identify where tensions and conflicts occur between the two groups. Such behavior, was uncommon prior to Nostra Aetate. It is unbelievable that these two groups can come together to not only discuss their issues but to an end to them. Nostra Aetate has been revolutionary in the changes regarding religious relations.Organizations have been formed for the sole purpose of educating people on religion. Universities make religious classes mandatory. Nostra Aetate is also important because the Catholic Church sets an example for all of its followers. If the Church accepts all religions, then maybe all Catholics will start to feel the same. Nostra Aetate has of course not destroyed all unwelcoming feelings towards religions, but it has at least decreased the criticisms. It has surely been a momentary document â€Å"in our time. † | |Works Cited Akasheh, Khaled. Nostra Aetate: 40 Years Later. † New Home Page Navigation Top. 28 June 2006. Web. 18 Oct. 2010. <http://www. ewtn. com/library/CHISTORY/chrstnsmslms. HTM>. Kasper, Walter C. â€Å"Welcome to the Vatican's Commemoration of the 40th Anniversary of Nostra Aetate. † Council of Centers on Jewish-Christian Relations. 25 Oct. 2005. Web. 19 Oct. 2010. <http://www. ccjr. us/dialogika-resources/documents-and-statements/roman-catholic/kasper/654-wk05oct27>. Telenet Service. Web. 18 Oct. 2010. <http://users. telenet. be/mb10366/>.

Confucianism vs Taoism Essays

Confucianism vs Taoism Essays Confucianism vs Taoism Paper Confucianism vs Taoism Paper n. d. Web. http://ctext. org/analects/wei-zheng. 6 Mar. 2013. Red Pine. Tao Te Ching. N. p. , n. d. Web. https://elearning. uh. edu/bbcswebdav/pid-394869-dt-content-rid 1739781_1/courses/H_20131_CHNS_3354_11272/red_pine_dao. htm. 6 Mar. 2013

How to Make Floam

How to Make Floam Floam  is a slimy substance with polystyrene beads in it that kids can mold into shapes. You can sculpt with it or use it to coat other objects. You can store it to reuse it or allow it to dry if you want permanent creations. Its a lot of fun, but not always easy to locate. You might be able to buy it at some stores and online, but you can make a type of Floam yourself. As with slime, its very safe, though anything containing food coloring can stain surfaces. Dont eat Floam. Polystyrene beads simply arent food. How to Make Floam Difficulty: Easy Time Required: This is a quick project: It takes only minutes Supplies 2 tsp. borax1/2 cup water1/4 cup white glue (such as Elmers)1/4 cup waterFood coloringA resealable plastic bag1 1/3 cups polystyrene beads Steps Dissolve 2 teaspoons of  borax completely in 1/2 cup (4 ounces) of water. Two teaspoons of borax will produce a stiff product. If you want more flexible Floam, try 1 teaspoon of borax instead.In a separate container, mix 1/4 cup (2 ounces) of white glue and 1/4 cup of water. Stir in food coloring.Pour the glue solution and the polystyrene beads into a plastic bag. Add the borax solution and knead it until its well mixed. Use 1 tablespoon of the borax solution for a very fluid Floam, 3 tablespoons for average Floam, and the entire amount for stiff Floam.To keep your Floam, store it in a sealed bag in the refrigerator to discourage mold. Otherwise, you can allow it to dry into whatever shape you choose. Tips for Success How it works: The borax reacts to crosslink the polyvinyl acetate molecules in the glue. This forms a flexible polymer.If you use a 4-percent solution of polyvinyl alcohol instead of glue, you will get a more transparent product that will hold shapes better.You can find polystyrene beads at craft stores, usually as fillers for bean bags or dolls. You can grind plastic foam cups using a cheese grater if you like.

4 Teaching Philosophy Statement Examples

4 Teaching Philosophy Statement Examples An educational philosophy statement or teaching philosophy statement is a brief essay that all nearly prospective teachers are required to write. Vanderbilt University explains: A teaching (philosophy) statement is a purposeful and reflective essay about the author’s teaching beliefs and practices. It is an individual narrative that includes not only one’s beliefs about the teaching and learning process but also concrete examples of the ways in which he or she enacts these beliefs in the classroom. A well-crafted teaching statement gives a clear and unique portrait of the author as a teacher. Ohio State Universitys Center for the Advancement of Teaching further explains that a teaching philosophy statement is important because a clear philosophy of teaching can lead to a change in teaching behavior and foster professional and personal growth. Examples of Teaching Philosophy Statements Sample 1 This passage is an example of a strong statement of teaching philosophy because it puts students where they belong in education: at the front and center of a teachers focus. An author who writes such as a statement is likely to continuously examine and verify this philosophy  by always ensuring that student needs are the primary focus of all lessons and schoolwork. My philosophy of education is that all children are unique and must have a stimulating educational environment where they can grow physically, mentally, emotionally, and socially. It is my desire to create this type of atmosphere where students can meet their full potential. I will provide a safe environment where students are invited to share their ideas and take risks. I believe that there are five essential elements that are conducive to learning. (1) The teachers role is to act as a guide. (2) Students must have access to hands-on activities. (3) Students should be able to have choices and let their curiosity direct their learning. (4) Students need the opportunity to practice skills in a safe environment. (5) Technology must be incorporated into the school day. Sample 2 The following statement is a good example of a teaching philosophy because the author emphasizes that all classrooms, and indeed all students, are unique and have specific learning needs and styles. A teacher with such a philosophy is likely to ensure that she spends time helping each student achieve her highest potential. I believe that all children are unique and have something special that they can bring to their own education.  I will assist my students to express themselves and accept themselves for who they are, as well embrace the differences of others. Every classroom has its own unique community; my role as the teacher will be to assist each child in developing their own potential and learning styles. I will present a curriculum that will incorporate each different learning style, as well as make the content relevant to the students lives. I will incorporate hands-on learning, cooperative learning, projects, themes, and individual work that engage and activate students learning.   Sample 3 This statement provides a solid example because the author emphasizes the moral objective of teaching: that she will hold each student to the highest expectations and ensure that each one is diligent in her studies. Implied in this statement is that the teacher will not give up on even a single recalcitrant student. I believe that a teacher is morally obligated to enter the classroom with only the highest of expectations for each and every one of her students. Thus, the teacher maximizes the positive benefits that naturally come along with any self-fulfilling prophecy. With dedication, perseverance, and hard work, her students will rise to the occasion. I aim to bring an open mind, a positive attitude, and high expectations to the classroom each day. I believe that I owe it to my students, as well as the community, to bring consistency, diligence, and warmth to my job in the hope that I can ultimately inspire and encourage such traits in the children as well. Sample 4 The following statement takes a slightly different tack: Classrooms should be warm and caring communities. Unlike the previous statements, this one minimizes the individuality of students and emphasizes that, essentially, it take a village to foster truly community-based learning. All teaching strategies then, such as morning meetings and community problem solving, follow this philosophy. I believe that a classroom should be a safe, caring community where children are free to speak their mind and blossom and grow. I will use strategies to ensure our classroom community will flourish, like the morning meeting, positive vs. negative discipline, classroom jobs, and problem-solving skills. Teaching is a process of learning from your students, colleagues, parents, and the community. This is a lifelong process where you learn new strategies, new ideas, and new philosophies. Over time, my educational philosophy may change, and thats okay. That just means that I have grown and learned new things. Components of a Teaching Philosophy Statement A teaching philosophy statement should include an introduction, body, and conclusion- just as you would expect of your students if they were writing a paper. But there are specific components that you need to include in any such statement: Introduction: This should be your thesis statement where you discuss your general belief about education (such as: I believe all students have a right to learn) as well as your ideals in relation to teaching. You should begin with the end, says James M. Lang in an Aug. 29, 2010, article titled, 4 Steps to a Memorable Teaching Philosophy published in The Chronicle of Higher Education. Lang says you should consider what the students will have learned once they depart your class, after having been guided by your teaching philosophy and strategies. Body: ​In this part of the statement, discuss what you see as the ideal classroom environment and how it makes you a better teacher, addresses student needs, and facilitates parent/child interactions. Discuss how  you would facilitate age-appropriate learning,  and how you  involve students in  the assessment process. Explain how you would put your educational ​​ideals  into practice. Lang says that you should clearly state your goals and objectives for students. Layout specifically what you hope your teaching will help students to accomplish. Be specific by telling a story or offering a detailed description of an innovative or interesting teaching strategy you have used, says Lang. Doing so, helps your reader understand how your teaching philosophy would play out in the classroom. Conclusion: In this section, talk about your goals as a teacher, how you have been able to meet them in the past, and how you can build on these to meet future challenges.  Focus on your personal approach to pedagogy and classroom management, as well as what makes you unique as an educator, and how you wish to advance your career to further support education. Lang notes that, while you dont need to use official citation style, you should cite your sources. Explain where your teaching philosophy originated- for example, from your experiences as an undergraduate, from a faculty mentor you worked with during your teacher-training program, or perhaps from books or articles on teaching that had a particular influence on you. Formatting Your Statement In addition to considering the type of teaching philosophy to write, Ohio State University offers some general formatting suggestions. The Ohio State University Center for the Advancement of Teaching states: Statement Format There is no required content or set format.  There is no right or wrong way to write a philosophy statement, which is why it is so challenging for most people to write one. You may decide to write in prose, use famous quotes, create visuals, use a question/answer format, etc. There are, however, some general rules to follow when writing a teaching philosophy statement, says the universitys teacher-training department: Keep it brief. The statement should be no more than one to two pages, according to the Ohio State University Center for the Advancement of Teaching. Use present tense, and write the statement in the first person, as the previous examples illustrate. Avoid jargon. Use common, everyday language, not technical terms, the university advises. Create a vivid portrait that includes strategies and methods ... (to help) your reader take a mental peek into your classroom, adds the Ohio State University Center for the Advancement of Teaching. Additionally, make sure you talk about your  experiences and  your  beliefs and ensure your statement is original and truly describes the methods and philosophy you would employ in teaching, the university adds.

Monaco grand prix economic impacts Essay Example | Topics and Well Written Essays - 1250 words

Monaco grand prix economic impacts - Essay Example They are typically organized by variable combination of national governmental and international non-governmental organizations (Sylt and Reid, 2010).† The Monaco Grand prix has great economical impacts; first and foremost it leads to technological development of mass communication especially satellite television. This development means that revenues from television to host the events increase overwhelmingly. The television rights are sold very highly like the rights to host Olympic games in 2000 in Sidney was over US$1 billion (Sylt and Reid, 2010). There is also a lot of corporate sponsorship which provide huge sums of money to the host countries. The event is also useful in marketing products and showcasing various country attractions hence attracting tourism and foreign investments. This event is one of the most significant events ready to transform the country. This leads to an increase in the volumes of tourists who come to the event for various reasons (Sharkey, 2011). In return, the huge visitor or tourist volumes increase the revenue received from the tourist and hence boosts the local trade. To host such an event, a lot of marketing and publicity has to be done, this leads to the host country being known world wide and having a positive image which in return boost tourism even during the non pick periods (Sharkey, 2011). Hosting such a mega event gives the host country a chance to be put on the world map, by providing significant exposure to the world. They serve as a platform to show the cultural, economical and political power of the host. By hosting such a significant event it shows that the country has entered the international scene as a major figure. This has been the case for countries like Singapole, Japan which hosted the 2002 FIFA World Cup, South Korea etc which little was known about them but after hosting sporting events their economies emerged and the political status became known

Types of My Favorite Movies Essay Example | Topics and Well Written Essays - 500 words

Types of My Favorite Movies - Essay Example (5) findings, 44.9% of driving incidents in action movies are often shown. Driving, speeding and taking a break with screeching tires, sudden and quick breaking are among the risk behaviors depicted in action movies in which only a few of the risky acts appears to be followed by a crash of traffic. In such situations, the movies often show that, 2 people died on the spot, four escaped with minor injuries and no legal penalties were imposed on the driver. Thesis statement: Horror movies have one purpose that is clear. That is to develop the commercial credential of the movie director via portraying his skill and tactics at torture, brutal tracking and young women mutilation of screaming. Horror is a fantastic genre coupled with a science of fiction. The movies are significant in criticizing and projecting the issues happening in the current world. In addition to horror movies being scary, they often question gender and sex portrayal as well as capitalism role in the society. Despite their significance in the society, they have faced a lot of criticism. For instance, they have been perceived as harmful and misogynistic by film critics and feminists. On the contrary they are greatly consumed by audiences in particular to torture films. For instance, in the late 1970’s and early 1980’s some films were singled out as being extremely offensive despite their relevant accolades. Some of the films were such as the dressed to kill (1980), Halloween (1978) and maniac (1980). In these films, female characters were slain or brutally attacked when they indulged in sexual fantasies and situations (Joe 1). Comedy through humor helps in passing across various messages. Therefore, it helps individuals in defining there sense of people, world, societies, their desires, dreams and goals. Therefore, no matter how individuals interpret comedy messages, whether they disregard or accept them, to a great extent, they are socially influential. Comedy helps to portray the

Compare and contrast the different connections Essay

Compare and contrast the different connections - Essay Example Firstly, with respect to Buddhism, the reader can acknowledge the direct meaning of the term â€Å"karma† within the Buddhist tradition relates to action or doing. Within this understanding, there is a further separation between meanings as karma refers to actions that come from a sentient being and those that refer to the entire karmic teaching that encompasses the entire universe (Ciurtin 493). Within this, it is clear to understand that karma is not only something that is represented between human relations, but a static and very real concept that helps to define the universe itself and the mechanisms through which humans interact with one another. Perhaps the most basic level of understanding that exists within the Western world with reference to karma is with relation to the Hindu understanding of what it represents. As a direct result of the Hindu focus on reincarnation and the importance of allowing for positive deeds to determine whether or not one will achieve a higher station in the afterlife, karma within Hinduism is intrinsically tied to good deeds and good thoughts being rewarded and attributable to reciprocity in both the current life and the afterlife. Not surprisingly, by contrast and comparison, bad deeds and bad thoughts experience reciprocity in this life as well as the afterlife as well; within the Hindu tradition (Sharma 29). From such an understanding, the reader can assert that of the three religions that have thus far been discussed, it is the Hindu tradition that places the most immediate emphasis on karmic tradition and the need to integrate with it as a means of ensuring the afterlife and intrinsic happ iness within the present. Moreover, as a direct result of the karmic tradition within Hinduism and the belief that all living creatures have a soul, the need to protect those creatures and

Gone With The Wind Research Paper Example | Topics and Well Written Essays - 750 words

Gone With The Wind - Research Paper Example Authority/Credentials of the Author The author of the article, Neil Netanel is a professor at the UCLA School of Law where he has been since fall 2004. Prior to that, the author was a member of fuculty at University of Texas Austine School of Law for a decade. Here, the author was the White, Durkee and Arnold Centennial Law Professor. The author practiced law between 1981 and 1984 at Loeb and Loeb located in Los Angeles, as well as in Tel-Aviv at Ygal Arnon & Co. between 1985 and 1992. Concerning educational background, Netanel holds B.A. from Yale university received in 1976, J.D. received in 1980 from UC Berkely Boalt Hall School of Law and J.S.D. received in 1998 from Stanford University. Hence, Netanel is well educated making information that he provides reliable. With regard to experience, Netanel has authored and co-authored several texts used in learning institutions among other institutions today. He is mostly an expert in teaching and writing about free speech, copyright, te lecommunications law and policy, and international intellectual property. Some of the most recent books authorted by Neil include 2008 Copyright’ Paradox, The Development Agenda: Global Intellectual Property and Developing Countries (2008), From Maimonides to Microsoft; The Jewish Law of Copyright Since the Birth of Print (2011)Â  both published by Oxford University Press. From the evaluation of author experience, credentials and educational background, it is clear that he is well vast in this area of law and other isues sorrounding legality of copyright and free speech. Therefore, article is written by an experienced author, thus, the credibility of the information is trustworthy. Validity of Research The information provided in this research is of high quality because it achieves almost all the parameters that determine the validity and credibility of a research article. For instance, the article refers to several other sources of information, which are all referenced thro ught the article. Furthermore, since it is dicussing fair use, which is related to court issues, it also refers to several past court cases. These cases, especially landmark cases, provide adequate evidence for the argument that the aauthor puts across in this article. The references used and cited inside the text are also listed at the bottom of every page in the form of footnotes, which enhances the quality and validity of the information provided in the article. Evaluation of the evidence presented by the author in this article clearly indiactes that it supports the author’s claim about fair use. Moreso, the author refers to variuos sudies and research to draw his conclusion about this issue. The major conclusion from this research is that the courts have embraced tranformative use doctrine more that they did ten or twenty years ago, and this contributes to high win rates of defendants with regard to fair use. In addition, the author uses objective research to support his claim as opposed to personal opinion or narrative. This is because he draws information from several books, and in addition, uses emphirical data to as evidence to support his cl

Explain some theory that you have read about in relation to the Essay

Explain some theory that you have read about in relation to the pricing of products and discuss its usefulness - Essay Example In the marketplace, they encounter a wide array of vendors and product offerings with a complex variety of benefits, prices, terms, and promotional messages. Research findings suggest that much of what people do when they buy products and services follows a definite logic. They look for cues to help simplify decision making, and often rely on simple rules of thumb. Correspondingly, it is possible to identify patterns of behavior in the way buyers go about satisfying their needs (Morris, Morris, 1990). The business must consider the customers perception of price implementing strategies such as positioning, price points and fair pricing. Price alone can be used in several ways to attract customers. There are two opposing strategies to the pricing of a product. If the business expects to be the low-cost leader, it must price (position) lower than the competition. If it wants to signal high quality, it should price products higher than most of the competition. Some manufacturers and reta ilers use price as a signal of quality. Consumers often have few indicators of quality, so price may be perceived as one of the better available cues.   By studied these various psychological aspects of consumer behavior, it becomes possible to price products and services to be of maximum appeal to the target market. Certain brands and retailers position themselves as providing value and quality at a low cost. These retailers rely on loss leaders to get consumers in the door knowing that once in, consumers are more likely to shop for other things as well. There are certain specific prices (price-points) at which people become more willing to buy a certain type of product. ‘Under  £100’ is a popular price point. An amount below  £20 including sales tax is another popular price point because it is the most popular denomination of money that people typically carry with them.

Global Smartphone Industry Essay Example | Topics and Well Written Essays - 3500 words

Global Smartphone Industry - Essay Example Further Porter’s five forces will enable to analyze the competitive forces of Nokia. In the part about sstrategic alliances and global competitiveness the BCG matrix will represent Nokia’s portfolio. In the part about the organizational structure of Nokia a McKinsey model will establish connections between areas that influence the the company’s performance. The 21st century has brought significant changes into the different spheres of human lives. Thus, energy conservation, openings in genetics as well as new technology are now the integral part of every society. Modern technology is the most noticeable because people use different devices such as mobile phones for their everyday purposes. This technology now accelerates the speed of information processing allowing sharing of the real-time information and communication between people. Moreover, such a small device as smartphone opens more potential for businesses, it is used in education purposes, its social meaning is great today. While the global traditional phone market is struggling with the recession as a result of the global economic downturn, the market of smartphones is growing. So the competition between the biggest manufacturers and providers grows as well. The following paper will examine the smartphone industry competitiveness, evaluating the nature of the industry competit ion that Nokia, a Finnish multinational company, faces in front of new mobile operating systems. Further it will discuss the impact of the global smartphone industry competition on Nokia’s smartphone market share and income. It will carry out a critical assessment regarding Nokia strategic alliance with Microsoft. The nature of the competition between different organizations in numerous spheres around world is changing. Due to the financial capital are still deficient and markets are inconsistent. All these factors call constant changes in all areas of business environment. Other features of the modern

Explain some theory that you have read about in relation to the Essay

Explain some theory that you have read about in relation to the pricing of products and discuss its usefulness - Essay Example In the marketplace, they encounter a wide array of vendors and product offerings with a complex variety of benefits, prices, terms, and promotional messages. Research findings suggest that much of what people do when they buy products and services follows a definite logic. They look for cues to help simplify decision making, and often rely on simple rules of thumb. Correspondingly, it is possible to identify patterns of behavior in the way buyers go about satisfying their needs (Morris, Morris, 1990). The business must consider the customers perception of price implementing strategies such as positioning, price points and fair pricing. Price alone can be used in several ways to attract customers. There are two opposing strategies to the pricing of a product. If the business expects to be the low-cost leader, it must price (position) lower than the competition. If it wants to signal high quality, it should price products higher than most of the competition. Some manufacturers and reta ilers use price as a signal of quality. Consumers often have few indicators of quality, so price may be perceived as one of the better available cues.   By studied these various psychological aspects of consumer behavior, it becomes possible to price products and services to be of maximum appeal to the target market. Certain brands and retailers position themselves as providing value and quality at a low cost. These retailers rely on loss leaders to get consumers in the door knowing that once in, consumers are more likely to shop for other things as well. There are certain specific prices (price-points) at which people become more willing to buy a certain type of product. ‘Under  £100’ is a popular price point. An amount below  £20 including sales tax is another popular price point because it is the most popular denomination of money that people typically carry with them.

TOM CREEKS PTY Essay Example | Topics and Well Written Essays - 250 words

TOM CREEKS PTY - Essay Example The current capital employed by the company is $3500, 000 and that is the price that we are putting on the table, as a result, we are which means that we are not paying any goodwill to the company and taking over a profitable business. This is a good thing as we are investing in a profitable asset.Sir, I may also like to present you the profitability report of the company. The company has earned a profit of $653,000 in the last fiscal year. If this trend continues and we invest in the company, we are going to earn an ROI of 19%. This very good return and will earn us a profit rate greater than if we deposit the money in our bank account. This ROI is among the return rates on higher sides and will be able to help us earn a decent amount of return on our investment.As far as the share capital is concerned, it is around 56% of the company's resources. This is an ideal ration and the company is neutrally geared. Due to this, our interest expenses will be low and we will be able to retain much of what we earn. Similarly, the company's working capital is in a very good position. We can easily clear our debts without endangering the company's liquidity position. Similarly, as we can see that the company has idle cash lying around in the form of excess working capital, we can put it to interest earning securities and this will further improve the company's profitability and we help us recover our investment.In the end,

Ambedkar Open University (BAOU) Essay Example for Free

Ambedkar Open University (BAOU) Essay Dr. Babasaheb Ambedkar Open University (BAOU), Ahmedabad was established in 1994 by the Gujarat State Legislature. It is the seventh Open University in the country in terms of their establishment. The University offers 72 programs with an enrolment of more than 1, 00,000 learners. The University has established regional centre on the campus of South Gujarat University, Rajkot and has initiated the process of another establishing regional centre on the campus of North Gujarat University, Patan. It has jurisdiction over the whole state of Gujarat. The main objectives of the university are to advance and disseminate learning and knowledge by a diversity of means, including use of any communication technology and to provide opportunities for higher education to a large segment of the population. The university encourages the Open University and distance education system in the educational pattern of the State. The university is open to all persons irrespective of classes, castes, creed or religion. Education is an important situation all over the world, and is maybe one of the most forgotten topics in the underdeveloped countries. This is the main reason why they don’t contribute to the progress of their own countries. Education is a human right, and as a fundamental right it is the responsibility of governments to provide it. The most important thing is that education influences human development, economic growth and the fundamental requirement for democracy. It is important in a country to invest a big part of the profits in education, because in many countries, governments prefer to invest in weapons without thinking that they should give another direction to the resources from the military where war and win are the most important thing. The government is blind, and they want to see first in the outside than in the inside, when there are more important things to fulfill like basic needs including food, clothing and shelter. Another important reason why it is necessary to invest in education is because children are being prepared to be poor laborers, just as the people years ago. Instead of preparing them for the future, they have been sent to the past with obsolete laws. There is a big necessity for programs that can teach the responsible use of resources, because without the right knowledge these people without education could be wasting a lot of resources and at the same time could be contributing to an unsustainable development. When speaking of development, the role of women is important in these processes, because in the countries  with the highest levels of human development it is declared that they offer equal opportunities and gender equity in their societies. It means that women can reach high positions, and they can do many of the things that were restricted to them a few years ago. When people see

About Pakistan International Airline Pia Management Essay

About Pakistan International Airline Pia Management Essay We will have to selectd Pakistan International Airlines for our report. And we are supposed to write a report where our major area of concern is employee relations against a changing background and nature of industrial conflict and the resolution of collective disputes. Due to the prevailing strict security conditions, we were unable to visit PIA for collecting information. Therfore, information regarding PIA is largely collected from internet. Executive summary In the beginning of our report, we have a brief background regarding PIA About Pakistan International Airline (PIA): Pakistan International Airlines usually better known as PIA can sketch its beginning to the days when Pakistan had not yet achieved independence from the  British Raj and is a public sector venture of Government of Pakistan. In 1946, the founder of Pakistan Muhammad Ali Jinnah  apprehended the need for a flag carrier for the prospective country and for this purpose the founder of the country requested financial help from a wealthy capitalist  Mirza Ahmad Ispahani. PIA was first known as Orient Airways, and was registered in  Calcutta  on 23 October 1946. PIA bought 3  DC-3  airplanes in February 1947 from a corporation in Texas and achieved a license to fly in May of the same year. Later, the airline started its operations in June, providing services from  Kolkata  to  Sittwe  and  Yangon. This was the first position second-world-war airline flight by a  South Asian  registered airline company. Orient Airways (early name of PIA) began operations for the ne w country (Pakistan) when it came into being on 14 August, 1947. (PIA, 2012) PIA was once considered as Asias best airline.  PIA is headquartered at  Jinnah International Airport  in  Karachi  and PIA provides services to 24 domestic destinations and 38 international destinations in 27 countries across Asia, Europe and North America. PIAs major bases are at Karachi, Lahore and Islamabad. Whereas, PIAs secondary bases entail  Peshawar,  Quetta, Faisalabad,   Multan and Sialkot. Through secondary bases PIA connects the metropolitan cities with the main bases, the  Middle East,  Europe, and the  Far East. It is largely owned by the  Government of Pakistan  and is regulated by the Ministry Of Defense as an autonomous body. PIA employs 18,043 individuals as of May 2008. (PIA, 2012) Outcome: 1st Tasks for P1: The unitary and pluralist perspectives of employee relations: Since the 1980s, there has been a major standard change in managing employee relations to one stressed on more strategic and incorporated frameworks that are based on employee dedication and mutual workplace interests, as an alternative of the traditional managerial control and conflicts between employers and employees. According to Alan Fox managers have different frames of reference' and everyone has a frame of reference, which can be identified as a lens with the help which one perceives employment relations. Number of other authors also argued that the managers frame of reference impacts how these perspectives are understood and used or not used.  The two well known kinds of ER perspectives are: unitary and pluralist. Before explaining the two main kinds of ER perspectives, we would first like to explain what frame is. Frames: According to Alan Fox, a frame is basically a sociological point of view that may assist in building of a frame of reference with the help of which issues of industrial relations can be observed practically and placed more open to solutions. (Fox, 1966) Unitary perspective: According to Michael Armstrong, the unitary perspective is basically held by managements who perceive their task as that of directing and controlling the employees to accomplish economic and growth objectives. To this end, management thinks that it is the rule-making power. Management tends to observe the venture as a unitary system with single source of authority, itself, and single focus of loyalty, the organization. It admires the good quality of teamwork, where everyone struggles together for a common objective and everyone accepts their place and work willingly, following the leadership of the selected manager. This unitary view, which is basically autocratic and dictatorial, has sometimes been stated in agreements as managements right to manage. The philosophy of HRM with its focus on commitment and support is based on the unitary perspective. (Armstrong, 2006) Characteristics of unitary perspective: First, there is only one source of power in organization, which is usually the management.  Second, the function of organizational leaders is to encourage loyalty and commitment among employees.  Third, organizations are observed as teams that are working together for common or mutual goals and objectives, and there are also no conflicts of interests between managers and employees.  Fourth, the management must represent effective leadership to achieve organizational goals objectives.  Ã‚  Fifth, Trade unions are not perceived as significant for the pleasant managing of conflicts. Sixth, conflicts in the organization are seen negatively and they are dysfunctional and results to disloyalty, thus harming the well-being of the organization.  Ã‚  Seventh, the state is autonomous and forms industrial relations systems (IR). Advantages of unitary perspective: Following are some of the advantages of unitary perspective of employee relations. A major advantage of the unitary perspective is that it openly wants to incorporate employer and employee interests, so that it can enhance employee commitment and loyalty. The unitary perspective also focuses on the role of managers in achieving win-win situations for employees and organizations, wherein their interests can be properly associated with each other Managers are forced to go beyond their managerial styles of managing employee relations and focuses on their leadership abilities and if they can be persuasive and prominent leaders in the organization, there will be no strong demand for trade unions. The unitary perspective is fundamentally individualist in its employee relations approach, which works best for individualist IR systems. Many IR systems all over the world have changed from the collectivist IR standards to individualist standards. Therefore the unitary perspective will be mainly valuable for this kind of IR perspective. Disadvantages of unitary perspective: Following are some of the disadvantages of the unitary perspective of employee relations. The main disadvantage of unitary perspective is the lack of understanding that there are power inequalities between employers and employees which will create different kinds of conflicts. Managers often use greater power over their workforce in shaping work conditions In unitary perspective, conflict is treated too negatively, and not seen as a force that imitates inequalities and which can be used as opportunities to recover work harmony. In unitary perspective, it is ambiguous how individual worker attitudes can be effectively integrated into the organizational objectives, because the unitary perspective is very normative and lacks explanation of how common interests can be recognized and distributed across organizations. Pluralist perspective: According to Alan Fox, an industrial organization is a plural culture, including many connected but separate interests and objectives which should be sustained in some kind of balance. In place where business unity reflected in a solitary focus of authority and loyalty, management has to accept the existence of opponent sources of leadership. It has to face the fact that a business venture has a triple personality: it is at once an economic, a political and a social organization. In the first, it generates and distributes profits. In the second, it represents a system of government in which managers jointly exercise authority over the managed, but are also themselves involved in a complex pattern of political relations. Its third personality is discovered in the plant community, which develops from below out of face-to-face relations based on common interests, attitudes, beliefs and values between diverse groups of employees. (Alan Fox, 2006) Whereas Cave (1994) describes pluralism as, an equilibrium of power between two controlled interests and a adequate degree of trust within the relationship for each side to value the others lawful interests, and for both sides to renounce from pushing their interest separately to the point where it became impossible to keep the show on the road. (Cave, 2006) Characteristics of pluralist perspective: First, pluralist theory considers that the workplace is composed of different sets of beliefs, standards and attitudes. Second, there are opposite sources of leadership in organizations.  Third, conflicts are expected because there are inborn opposing interests and sometimes conflicts can even be useful, if recognized and controlled within institutional reactions.  Fourth, the function of the management is to arbitrate between competing interests.  Fifth, Trade unions are lawful legislative body of employees, and they are perceived positively because they help employees focus on their decision-making power. Sixth, the state encourages public interest. Seventh, employee relations constancy can be achieved through a chain of negotiations between managers and employers through the collective bargaining method. Advantages of pluralist perspective: Following are some of the advantages of pluralist perspective of employee relations. Pluralist theory focuses on the effectiveness of industrial relations involvements as it assists in resolving conflicts. Pluralist perspective also considers other different decision-making practices such as communication and consultation with employees. In pluralist perspective conflict is not ignored, but are dealt effectively through stakeholder involvement. Conflict can then be used to recognize fundamental tensions, so that they can be recognized and properly rectified. The pluralist perspective does not ignore or disregard the part of trade unions in managing employee-employer conflicts rather it embraces a broader range of employee relations policies. Disadvantages of pluralist perspective: Following are some of the disadvantages of pluralist perspective of employee relations. The major weakness of the pluralist perspective is the tendency to settle on set of rules and procedures and ignore the methods that also contribute to the resolution of conflicts. The pluralist perspective is unable of recognizing that the state also represents business interests and not just public interests. The pluralist perspective may stress too much on worker interest, which can result to the inefficiencies of collective bargaining practices. Frame of reference at Pakistan International Airlines (PIA): According to our findings and observations, Pakistan International Airlines (PIA) uses unitary frame of reference and following are some of the justification for proving that PIA uses unitary frame of reference. The first and main characteristic of a unitary perspective is that the source of power in organization is with the management which is exactly the same in PIA. The power to make any major decisions is with the management of the PIA because PIA is regulated by Ministry of Defense as an autonomous body. The management bodies of PIA encourages loyalty and commitment among employees through number of different monetary and non-monetary approaches, this is another characteristic of a unitary perspective. Employees of the PIA struggle for one common goal which to attain profit by delivering the best possible services to their valued customers. This is also one of the characteristic of unitary perspective. Conflicts are perceived negatively because this negatively affects their business for example, the recent strikes of the employees regarding pay increase severely affected PIAs business. One of the characteristics of the unitary perspective is that it ignores the involvement of trade union and this what the PIAs management did several times in the recent time which lead them to face number of problems. These evidences clearly indicate that PIA uses unitary perspective of employee relations. Tasks for P2: Importance of trade union: Before we discuss importance of trade union it is important first to know what trade union is. Trade union: According to Michael Armstrong, the basic purpose of trade unions is to encourage and protect the interests of their members. They are there to equalize the balance of authority between employers and employees. The basis of the employment relationship is the contract of employment. But this is not a contract between equals. Employers are more or less always in a stronger position to order the terms of the contract than individual employees. Trade unions give workers with a collective voice to make their needs known to management and as a result bring real and preferred conditions closer together. This pertains not only to terms of employment such as pay, working hours and holidays, but also to the way in which employees are treated in such aspects of employment as the remedy of grievances, authority and redundancy. Trade unions also exist to let management know that there will be, from time to time, a substitute view on key matters affecting employees. More largely, unions may see th eir role as that of contributing with management on decision making on matters affecting their members interests. (Armstrong, 2006) In short trade unions have two specific functions, to protect their members through collective bargaining, better terms and conditions, and to support and counsel to their members as individual employees. In additional trade union roles involves, that of providing legal, financial and other services to their members. Importance of trade union: Employees are not the only ones who enjoy the benefits of joining the trade union but its the employer or the organization that enjoys and takes advantage of the benefits of trade union as well. Employees can use trade union as tool through which their voices can be reached to the employer or management. Whereas, trade union greatly help employer or management as it saves their huge amount of time not only in solving their issues but also when they wishes to implement any new rule they do not need to inform each and every employees rather they inform only the trade union leader who then informs all their members. The importance of the trade union can observe by the following advantages of trade union. Representation: As mentioned earlier, trade union represent employees when they an issue at work. For example, if an employee considers he/she is being unjustly treated, he/she can ask the union representative to assist sort out the problem with the employer. In short, union is there to represent employees. Negotiation: Trade union representatives negotiate the problems that affect employees working in an organization. There may be a dissimilarity of opinion between management and union members. Trade unions negotiate with the employers to discover remedy to these problems. Trade union usually negotiates for the problems such as pay, working hours and changes to working practices. In many organizations usually there is a formal agreement between the union and the management which declares that the union has the right to negotiate with the employer. Voice in decisions affecting employees: The economic protection of workforce is determined not only by the level of wages and duration of their employment, but also by the managements personal rules which incorporate selection of workforce for layoffs, promotion and transfer. These policies basically directly affect workforce. In order to ensure these policies are developed fairly, the involvement of unions in such decision making is a way through which employees can have their voice in the decision making to protect their interests. Member services: Now a day trade unions are providing number of different services to their members in order to ensure their rights are not ignored and to make their members effectives. These services involves education training, legal assistance, welfare benefits and financial discounts etc. On the basis of the above benefit of trade union to the organization, we can conclude that Trade union can greatly help PIA to resolve different issues. For example, recently PIAs employees were on strike because they wanted to increase their pay levels, if the management of the PIA had good relations with the trade union they might not had faced this problem. Therefore, considering the importance of trade union PIA must value their trade union otherwise they will face different other serious problems in the near future. Tasks for P3: Role of trade union in employee relations: Trade union plays an important role in forming peoples working lives in almost every part of the world today, though their power in this respect has decreased in current times. The percentage of employees who are members of unions fell in the first decade of the twenty-first century, though this decrease was modest, and far less impressive than the decrease of the previous two decades. The experience of firms and industries to greater market pressures, a growing movement in outsourcing and the growth in unusual employment, employer supported forms of involvement and representation, and the nuisance of legal limitations on the ability of unions to recruit, organize, collectively bargain and take industrial action, has all added to a quick fall in membership. Despite the acceptance of different internal strategies and the introduction of laws pushing employers to recognize unions, the downward trend in membership all the same continued in recent years, although at a slower pace. As mentioned earlier that employees are not the only ones who enjoys the benefits of joining the trade union but its the employer or the organization that enjoys and take advantage of the benefits of trade union as well. Employees can use trade union as tool through which their voices can be reached to the employer or management. Whereas, trade union greatly help employer or management as it saves their huge amount of time not only in solving their issues but also when they wishes to implement any new rule they do not need to inform each and every employees rather they inform only the trade union leader who then informs all their members. Following are some roles of trade union in employee relations: Member services Voice in decisions affecting employees Negotiation Representation The roles of the trade union mentioned above are briefly explained earlier in our report. Tasks for P4: Role of main actors in employee relations: According to (1966), the term employment relationship basically explains the interconnections that exist between employers and employees in the place of work. These interconnections may be formal, for example contracts of employment, procedural agreements. Or they might be informal interconnections as well in the form of the psychological contract, which states certain assumptions and expectations regarding what managers and employer have to provide and are willing to deliver. Employer and employee may also have an individual dimension, which pertains to individual contracts and prospects, or a collective dimension, which pertains to relationships between management and trade unions. (Kessler and Undy, 2006) Whereas according to Michael Armstrong, the parties of the employee relations are managers, employees and employee representatives (union). The substance includes the job, reward and career of individuals and the communications and culture of the organization as it directly affects them. It may also involve collective agreements and mutual employee relations like works councils etc. The formal aspects contain rules and procedures, and the informal dimension contains understanding, expectations and assumptions. At last, the employment relationship exists at different levels in the organization such as management to employees usually, and managers to individual employees and their representatives. The function of the relationship will also be affected by practices such as communications and consultation, and by the management style existing throughout the organization or implemented by individual managers. (Armstrong, 2006) Parties in the employee relations Role of the parties in the employee relations: The role of the employees in the employee relations is to consult their representative or union at times when he/she feels they are treated unfair or if they wish for a demand such pay increase, decrease in working hours or holidays etc. Another role of employees in the employee relations is they must obey the orders from trade union. Whereas union or employees representative have two specific functions, to protect their members through collective bargaining, better terms and conditions, and to support and counsel to their members as individual employees. Similarly, the role of managers or employers is to maintain good relationship with the unions representatives which otherwise leads to different major issues. The role of managers or employers in employee relations is to communicate new policies and regulations to their employees through employee representatives or unions. Tasks for M1: An effective judgment of PIA: Due to the prevailing strict security conditions in Pakistan, we were unable to visit PIAs office for collecting data. Therefore, we had to collect data via electronic sources. Disputes at PIA: According to the report of Mr. Qasim Moini the correspondent of the Dawn News that five flights were affected on Friday after a clash over pay and a working agreement between the management and pilots of PIA threatened to have an effect on the flag carrier`s plan. (Dawn News, 2011) The Pakistan Airline Pilots` Association (Palpa) the delegate body of most of PIAs 450 or so pilots advised its members to go by the book, read articles that allow them to take 10 days off in a month and not fly until given notice 12 hours before a flight in writing. Another dispute at PIA was very shocking in terms of financial cost and passengers dissatisfaction. According to Dawn News on 10th of February 2011, employees strike at PIA that lasted for four days, trapped thousands of passengers and abandoned nearly three dozen domestic and international flights on Friday. PIA spokesman Mashhood Tajwar said 33 flights were canceled. No PIA planes were flying to or from the capital, Islamabad, while the timetable in the southern city of Karachi has been disturbed. Even though PIA is at the brick of bankruptcy but this strike cost PIA a loss of about $22 million. (Dawn News, 2011) The problem was later resolved by federal Interior Minister Rehman Malik by meeting with the employees association leader Suhail Baluch. Being an HR manager of PIA our decision: An ideal manager is one that never gives a chance to the birth of dispute, but since we know that managing human is not an easy task and their behavior is not constant and it changes situation to situation. It is also a believe at large that where human exist there must be some sort disputes because of the nature of human being is they often challenges or perceive things wrongs or take things personally. Our decision for the dispute of the pilot over pay increase and employment hours, we would first look at our policies and employment contract in order to know what they state. After doing so we will critically analyze the party that is wrong (the management of PIA or the pilots). Even if the management of PIA is right, we will still not try give a chance to disputes because it badly effects not only the business but it also dissatisfy customers because as a result of dispute customers may not be served with in the scheduled time. Whereas, even if the pilots were right then we being HR managers of PIA would try to the best of our abilities to carefully and effectively rectify this issue because as mentioned earlier the dispute can result in delays of flights which will financially affect PIA and it will dissatisfy customers as well. In order to rectify this issue, we would humbly request pilots to carry out their tasks on time. For this reason we would like to provide them with some extra incentives because they are working extra hours. And to rectify pay increase issue, we would have contacted employees representative of PIA and being ideal HR managers of PIA we would have adopted win-win approach. This approach basically states that some aspects must be tolerated by the management and some the by the employees representative (employees). We believe our decision will not only help PIA to rectify the arising issue but it will also help them not dissatisfy their employees and their customers as well. While for the second dispute (strikes of the employees of PIA), our decision is almost the same. We will first not give a chance to raise such issues. This issue clearly indicates that the management of PIA is not good towards their employees as a result they were on strike and faced PIA will loss of millions of dollar. According to our deep observation regarding the strike of the employees that lasted four consecutive days creates both a huge advantage and a huge disadvantage. The advantage of this issue for PIA could be a lesson that they should focus and give values to the issues of employees and the disadvantage of this strike is that employees showed their power that they are capable of doing anything with PIA if their wishes were not considered or valued in the future. We being HR managers of PIA would have consulted the union leader prior the issue had reach to a crucial level and in such situation we would have adopted you win-I lose approach because this approach would at least have saved the amount of loss that resulted as a consequence of the strike. Outcome: 2nd Task for P5: Importance of framework approach in industrial relations: Before we discuss why framework approach is importance in industrial relations, we would first like to explain what industrial relation is. Industrial relations: Industrial relations may basically be considered as a system of rules regulating employment and the behavior in which individual behave at work. The systems theory of industrial relations, as put forwarded by Dunlop (1958), described that the function of the system is to create the regulations and practical rules that govern how much is distributed in the bargaining practice and how the parties contributed to one another. (Dunlop, 2006) Industrial relations is described in many more or less formal or informal forms; in legislation and statutory orders, in trade union regulations, in collective agreements and arbitration awards, in social conferences, and in managerial decisions. The rules in industrial relations may be defined and logical, or ill-defined and illogical. Whereas, the only issue with industrial relations is that it does not adequately focus on the distribution of power between management and trade unions. Importance of framework approach in industrial relations: A framework is basically a supporting arrangement around which something can be constructed or a system of rules, ideas or principles that is used to plan or decide something. Framework approach is significant in industrial relations because it will help not only employees, employees representative but also the management or employer in showing them direction of their rights or authorities. Suppose an employee feels he/she treated unfairly such paid low or no holidays are given to him/her, the employee can consult their representative for this issue in order to rectify it. Similarly, if employer feels his/her legal orders are not obeyed, will consult employees representative in order to rectify this issue. This is all because of the proper framework, if there is no proper framework in industrial relations then, both employees and employers may not be able to resolve any issue. In simple words, we can say that framework approach to industrial relations helps in balancing the use of power both for employers and employees. It often observed that employers misuses their power and dictate their employees, to avoid such situations framework approach is used in industrial relations to maintain the balance of power between both the parties. Tasks for P6: Types of collective disputes: Before we discuss different types of collective disputes, it is important first to know what is a dispute and collective dispute. Employment disputes are basically divided into two main types Individual disputes: Collective disputes: As the name indicates, individual disputes are generally those that involve a single employee whereas collective disputes involve groups of workers usually represented by a trade union. The definition of a collective dispute is pretty wide and can involve issues in dispute such as terms and clauses of employment, physical working conditions, commitment, termination, duties of service, provision of work, regulation and a group of other issues associated with employment relations. Collective disputes are further divided into two sub-types which are: Rights disputes: Interests disputes: A rights dispute arises where there is disagreement over the implementation or understanding of legal rights. Whereas in contrast, an interest dispute involve disagreements over the determination of rights and responsibilities of those already exist. Interest disputes generally arise in the perspective of collective bargaining where a collective agreement does not exist. Dispute and their different types Elements of collective disputes: Elements of the collective disputes are usually the grievances between employees and employers. These grievances are usually formed either due misuse of power by the employer or by the disobeying the orders of employers by the employees. Following are some of the elements of collective disputes: When the normal methods of argument or negotiations between an employer and employee representatives fail to reach a conclusion a failure to agree must be recorded and a proper dispute course of actions should be appealed. The dispute methods must be in writing and, depending on the degree of the organization, it must give an opportunity for a dispute to be forwarded to a higher management-employee representative level. If the higher level of management-employee representative negotiation does not resolve the dispute then the issue should be forwarded to external conciliation. Logical time limits must be set for reference to the internal and external levels of a dispute method. In many cases employers and employee representatives may wish the dispute practice to provide for arbitration or mediation. It is advised for both the parties to try to resolve a dispute through conciliation before using these other types of dispute resolution. <

Metaphysical Explanation for the Number Three :: Philosophy

Metaphysical Explanation for the Number Three What is the Number Three? When examining what sort of existence the number three has, it is important first to understand exactly how it exists relevantly in the physical world. First of all, the primary existence of number three is not a tangible existence; one cannot walk through the forest and find threes growing wild with beautiful, silky, burnt orange and maroon spotted petals and green leaves. Second of all, the number three cannot do anything by itself to declare its own existence in the physical. Unlike air, gravity, or time, which are also intangible but still capable of certain physical actions such as wind, combustion (air), gravitational pull (gravity), or orbits (time), the number three does not have the physical properties necessary to be detected by the senses of any terrestrial being by itself. So, exactly how does the number three exist? Well, it has a co-dependent existence; in order for three to exist, it requires something called "units." Three exists as an application of units, and units can be any existing thing with physical properties. The units are what determine the type of existence three has. If the unit is another application such as five, six, or seven, or a variable (a variable occurs when the units’ arrangement or amount varies) such as X or Y, then the existence is not yet detectable; this only creates another type of application or formula that requires units with physical proprieties to be "plugged into it" in order to be detected through the senses in the real world. There are two ways that three can be used as an application to units; it can be used in terms of quantitative measurement or it can be used in terms of sequences. Earlier I mentioned that you cannot walk through the forest and find threes growing wild. However, you can find three tiger lilies growing wild. The tiger lilies are the units and three is the application. This is an example of three applied as a quantitative measurement. In other words, three is the amount of tiger lilies growing. You can tell there are three tiger lilies if you count the first seen as one, the second as two, and then the third as three, and you see no other tiger lilies besides the ones counted.

Internet and Intranet Connectivity Through Wireless Local Area Network (Wlan)

CHAPTER 1 Introduction Chapter 1 Introduction 1. 1 What is WLAN? 1. 1. 1 WLAN Wireless Local Area Network (WLAN) is a kind of local area network which established using a wireless link between the service providers and the clients using some wireless equipment. This network development is based on the IEEE 802. 11 standard. 1. 1. 2 IEEE 802. 11 IEEE 802. 11 denotes a set of Wireless LAN/WLAN standards developed by working group 11 of the IEEE LAN/MAN Standards Committee (IEEE 802). The term 802. 11x is also used to denote this set of standards and is not to be mistaken for any one of its elements. There is no single 802. 1x standard. The term IEEE 802. 11 is also used to refer to the original 802. 11, which is now sometimes called â€Å"802. 11 legacy† [1]. The 802. 11 family currently includes six over-the-air modulation techniques that all use the same protocol. The most popular techniques are those defined by the b, a, and g amendments to the original standard; security was originally included and was later enhanced via the 802. 11i amendment. 802. 11n is another modulation technique that has recently been developed; the standard is still under development, although products designed based on draft versions of the standard are being sold. Other standards in the family (c–f, h, and j) are service enhancements and extensions or corrections to previous specifications. 802. 11b was the first widely accepted wireless networking standard, followed by 802. 11a and 802. 11g [1]. 802. 11b and 802. 11g standards use the 2. 40 GHz (gigahertz) band, operating (in the United States) under Part 15 of the FCC Rules and Regulations. Because of this choice of frequency band, 802. 11b and 802. 11g equipment can incur interference from microwave ovens, cordless telephones, Bluetooth devices, and other appliances using this same band. The 802. 1a standard uses the 5 GHz band, and is therefore not affected by products operating on the 2. 4 GHz band. Table 1. 1: Protocol Summary of IEEE 802. 11 Protocol Legacy 802. 11a 802. 11b 802. 11g 802. 11n Release Date 1997 1999 1999 2003 2006 Operating Frequency GHz 2. 4-2. 5 5 2. 4-2. 5 2. 4-2. 5 2. 4 and/or 5 Throughput (Typ) Mbps 0. 7 23 4 19 74 Data Rate (Max) Mbps 2 54 11 54 248 = 2Ãâ€" 2 ant Range (Indoor) meters ~25 ~30 ~35 ~35 ~70 Range (Outdoor) meters ~75 ~100 ~110 ~115 ~160 2 1. 2 Why it should be used? Bangladesh entered the Internet world in 1993 using offline E-mail services. Online Dial-up services started in 1996 through VSAT based data connectivity. But it is not possible to give a Dial-up connection to all because; it uses the BTTB’s telephone line. While Dial-up is active the phone line is busy and it is not possible to give a client more than 4/5 Kbps speed. Using an ADSL modem it can be increased to more than 2 Mbps. But it is not enough for a corporate user and also it is very costly and there are many other problems which has described below. The Ethernet connectivity can give a maximum of 100 Mbps. But its range is too small. Wireless LAN has vast benefits over wired network in some aspects. In our country especially in big cities like Dhaka, it is very hard job to establish a wired network all over the city. Because, it is over populated, buildings were made with out any proper plan and also the roads. Generally the wire lines are established over head, which is not so secured. Wire can be broken due to any kind of natural or man made problem. It may be theft. Or it can be misused by any one by taking a parallel line from it. It may create leak of data security. It is also very expensive to establish a copper wire network road by road and maintenance of it. Besides that there are many rivers, cannels in our county, and also hill tracks in some parts. It is not possible to give a wired network over those. For all those reasons it is not a wise decision to use a wired network in our country. A Wireless LAN can be more reliable, low cost, convenient network considering above aspects. There are a number of Internet Service Provider (ISP) companies in our country giving Wireless LAN support to the clients. Those are known as Wireless ISP. These ISPs give internet or intranet service to the clients as their requirements. Those networks are reliable and also secured. It is easy to establish a connection in the company’s coverage area using a wireless device at the client end. The Wireless ISP Company should have proper resources to give that coverage. A model of a Wireless ISP company’s wireless part for Bangladesh is given below. The nation wide link can be a optical fiber or microwave link. Here the main coverage is shown in Dhaka city and thus BSSs are shown at here is more than one. It can be expand the network in other areas by adding additional equipments required to establish a BSS. And also it can give coverage on other areas by establish same network on that area. Figure 1. 1: Model of a Wireless ISP 1. 3 Why one should be interested in WLAN field? The telecom industry is changing with breathtaking speed. There are a lot of telecommunication and Wireless ISP companies working in our country and there are a lot of companies to come. At present telecommunication is the most challenging and interesting field out of all other e ngineering fields. All the telecom company has some common structure. So, there are many similarities between a mobile or PSTN (Public Switched Telephone Network) operator and a Wireless ISP. The skills one gather from a Wireless ISP can use in the telecom companies. The man can be skilled on installing different devices, surveying a site, proposing a link budget. He can face the practical problems occur in installing radio networks and can be skilled in solving those problems and also troubleshoot the devices and the radio link. In the mobile operators, there are many restrictions. One can not work with all things. But as still Wireless ISP companies are smaller in our country one can get opportunity to work in different sections which will increase his experiences and skills. Lastly it can be say that, as it is a challenging field, the person likes facing challenges will enjoy working in this field 4 1. 4 Organization of this report This Internship report has seven chapters in total. The second chapter contains theory about the radio frequency properties and different modulation techniques In third chapter, different RF antennas and it accessories are described. Fourth chapter contains the Wireless LAN’s theory and architecture in brief. Chapter five analyzes to survey a site, and how to budget a link. The sixth chapter describes the device installation process for the APERTO and CANOPY devices. The seventh and final chapter is the concluding chapter where limitations of this works are reported and few suggestions of our work are provided along with the concluding remarks. 1. 5 Aims and objectives 5 RF Properties and Modulation Techniques CHAPTER 2 6 Chapter 2 RF Properties and Modulation Techniques 2. 1 Radio Frequency 2. 2. 1 Radio Frequency Radio frequencies are high frequency alternating current (AC) signals that are passed along a copper conductor and then radiated into the air via an antenna. An antenna converts/transforms a wired signal to a wireless signal and vice versa. When the high frequency AC signal is radiated into the air, it forms radio waves. These radio waves propagate (move) away from the source (the antenna) in a straight line in all directions at once. 2. 2. 2 RF Behaviors RF is sometimes referred to as â€Å"smoke and mirrors† because RF seems to act erratically and inconsistently under given circumstances. Things as small as a connector not being tight enough or a slight impedance mismatch on the line can cause erratic behavior and undesirable results. The following sections describe these types of behaviors and what can happen to radio waves as they are transmitted. Gain Gain, illustrated in Figure 2. 1, is the term used to describe an increase in an RF signal' amplitude [2]. Gain is usually an active process; meaning that an external s power source, such as an RF amplifier, is used to amplify the signal or a high-gain antenna is used to focus the beam width of a signal to increase its signal amplitude. Figure 2. 1: Power gain However, passive processes can also cause gain. For example, reflected RF signals combine with the main signal to increase the main signal' strength. Increasing the RF s signal' strength may have a positive or a negative result. Typically, more power is s better, but there are cases, such as when a transmitter is radiating power very close to legal power output limit, where added power would be a serious problem. 7 Loss Loss describes a decrease in signal strength (Figure 2. 2). Many things can cause RF signal loss, both while the signal is still in the cable as a high frequency AC electrical signal and when the signal is propagated as radio waves through the air by the antenna. Resistance of cables and connectors causes loss due to the converting of the AC signal to heat. Impedance mismatches in the cables and connectors can cause power to be reflected back toward the source, which can cause signal degradation. Objects directly in the propagated wave' transmission path can absorb, reflect, or s destroy RF signals. Loss can be intentionally injected into a circuit with an RF attenuator. RF attenuators are accurate resistors that convert high frequency AC to heat in order to reduce signal amplitude at that point in the circuit. [2] Figure 2. 2: Power loss Being able to measure and compensate for loss in an RF connection or circuit is important because radios have a receive sensitivity threshold. A sensitivity threshold defined as the point at which a radio can clearly distinguish a signal from background noise. Since a receiver’s sensitivity is finite, the transmitting station must transmit signal with enough amplitude to be recognizable at the receiver. If losses occur between the transmitter and receiver, the problem must be corrected either by removing the objects causing loss or by increasing the transmission power. Reflection Reflection, (as illustrated in Figure 2. 3) occurs when a propagating electromagnetic wave impinges upon an object that has very large dimensions when compared to the wavelength of the propagating wave [3]. Reflections occur from the surface of the earth, buildings, walls, and many other obstacles. If the surface is smooth, the reflected signal may remain intact, though there is some loss due to absorption and scattering of the signal. Figure 2. 3: Reflection 8 RF signal reflection can cause serious problems for wireless LANs. This reflecting main signal from many objects in the area of the transmission is referred to as multipath. Multipath can have severe adverse affects on a wireless LAN, such as degrading or canceling the main signal and causing oles or gaps in the RF coverage area. Surfaces such as lakes, metal roofs, metal blinds, metal doors, and others can cause severe reflection, and hence, multipath. Reflection of this magnitude is never desirable and typically requires special functionality (antenna diversity) within the wireless LAN hardware to compensate for it. Refraction Refraction describes the bending of a radio wave as it passes through a medium of different density. A s an RF wave passes into a denser medium (like a pool of cold air lying in a valley) the wave will be bent such that its direction changes. When passing through such a medium, some of the wave will be reflected away from the intended signal path, and some will be bent through the medium in another direction, as illustrated in Figure 2. 4. [3] Figure 2. 4: Refraction Refraction can become a problem for long distance RF links. As atmospheric conditions change, the RF waves may change direction, diverting the signal away from the intended Diffraction Diffraction occurs when the radio path between the transmitter and receiver is obstructed by a surface that has sharp irregularities or an otherwise rough surface [3]. At high frequencies, diffraction, like reflection, depends on the geometry of the obstructing object and the amplitude, phase, and polarization of the incident wave at the point of diffraction. Diffraction is commonly confused with and improperly used interchangeably with refraction. Care should be taken not to confuse these terms. Diffraction describes a wave bending around an obstacle (Figure 2. 5), whereas refraction describes a wave bending through a medium. Taking the rock in the pond example from above, now consider a small twig sticking up through the surface of the water near where the rock. As the ripples hit the stick, they would be blocked to a small degree, but to a larger degree, the ripples would bend around the twig. This illustration shows how diffraction acts with obstacles in its path, depending on the makeup of the obstacle. If Object was large or jagged enough, the wave might not bend, but rather might be blocked. 9 Figure 2. 5: Diffraction Diffraction is the slowing of the wave front at the point where the wave front strikes an obstacle, while the rest of the wave front maintains the same speed of propagation. Diffraction is the effect of waves turning, or bending, around the obstacle. As another example, consider a machine blowing a steady stream of smoke. The smoke would flow straight until an obstacle entered its path. Introducing a large wooden block into the smoke stream would cause the smoke to curl around the corners of the block causing a noticeable degradation in the smoke' velocity at that point and a significant s change in direction. Scattering Scattering occurs when the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength of the signal, and the number of obstacles per unit volume is large [3]. Scattered waves are produced by rough surfaces, small objects, or by other irregularities in the signal path, as can be seen in Figure 2. 6. Figure 2. 6: Scattering Some outdoor examples of objects that can cause scattering in a mobile communications system include foliage, street signs, and lampposts. Scattering can take place in two primary ways. First, scattering can occur when a wave strikes an uneven surface and is reflected in many directions simultaneously. Scattering of this type yields many small amplitude reflections and destroys the main RF signal. Dissipation of an RF signal may occur when an RF wave is reflected off sand, rocks, or other jagged surfaces. When scattered in this manner, RF signal degradation can be significant to the point of intermittently disrupting communications or causing complete signal loss. 10 Second, scattering can occur as a signal wave travels through particles in the medium such as heavy dust content. In this case, rather than being reflected off an uneven surface, the RF waves are individually reflected on a very small scale off tiny particles. Voltage Standing Wave Ratio (VSWR) VSWR occurs when there is mismatched impedance (resistance to current flow, measured in Ohms) between devices in an RF system. VSWR is caused by an RF signal reflected at a point of impedance mismatch in the signal path. VSWR causes return loss which is defined as the loss of forward energy through a system due to some of the power being reflected back towards the transmitter. If the impedances of the ends of a connection do not match, then the maximum amount of the transmitted power will not be received at the antenna. When part of the RF signal is reflected back toward the transmitter, the signal level on the line varies instead of being steady. This variance is an indicator of VSWR. [2] As an illustration of VSWR, imagine water flowing through two garden hoses. As long as the two hoses are the same diameter, water flows through them seamlessly. If the hose connected to the faucet were significantly larger than the next hose down the line, there would be backpressure on the faucet and even at the connection between the two hoses. This standing backpressure illustrates VSWR, as can be seen in Figure 2. . In this example, you can see that backpressure can have negative effects and not nearly as much water is transferred to the second hose as there would have been with matching hoses screwed together properly. Figure 2. 7: VSWR-like water through a hose VSWR Measurements VSWR is a ratio, so it is expressed as a relationship between two numbers. A typical VSWR value would be 1. 5:1. The two numbers re late the ratio of impedance mismatch against a perfect impedance match. The second number is always 1, representing the perfect match, where as the first number varies. The lower the first number (closer to 1), the better impedance matching your system has. For example, a VSWR of 1. 1:1 is better than 1. 4:1. A VSWR measurement of 1:1 would denote a perfect impedance match and no voltage standing wave would be present in the signal path. Effects of VSWR Excessive VSWR can cause serious problems in an RF circuit. Most of the time, the result is a marked decrease in the amplitude of the transmitted RF signal. However, 11 since some transmitters are not protected against power being applied (or returned) to the transmitter output circuit, the reflected power can burn ut the electronics of the transmitter. VSWR' effects are evident when transmitter circuits burn out, power s output levels are unstable, and the power observed is significantly different from the expected power. The methods of changing VSWR in a circuit include proper use of proper equipment. Tight connections between cables and connectors, use of impedance matched hardware throughout, and use of high-quality equipment with calibration reports where necessary are all good preventative measures against VSWR. VSWR can be measured with high-accuracy instrumentation such as SWR meters, but this measurement is beyond the scope of this text and the job tasks of a network administrator. 2. 2 Spread Spectrum 2. 2. 1 Spread Spectrum Spread spectrum is a communications technique characterized by wide bandwidth and low peak power. Spread spectrum communication uses various modulation techniques in wireless LANs and possesses many advantages over its precursor, narrow band communication [4]. Spread spectrum signals are noise-like, hard to detect, and even harder to intercept or demodulate without the proper equipment. Jamming and interference have a lesser affect on a spread spectrum communication than on narrow band communications. For these reasons, spread spectrum has long been a favorite of the military. 2. 2. 2 Narrow Band Transmission A narrowband transmission is a communications technology that uses only enough of the frequency spectrum to carry the data signal and no more, spread spectrum is in opposition to that mission since it uses much wider frequency bands than is necessary to transmit the information. This brings us to the first requirement for a signal to be considered spread spectrum. A signal is a spread spectrum signal when the bandwidth is much wider than what is required to send the information. [4] Figure 2. 8 illustrates the difference between narrowband and spread spectrum transmissions. One of the characteristics of narrow band is high peak power. More power is required to send a transmission when using a smaller frequency range. In order for narrow band signals to be received, they must stand out above the general level of noise, called the noise floor, by a significant amount. Because its band is so narrow, and high peak power ensures error-free reception of a narrow band signal. 12 Figure 2. 8: Narrow band verses Spread Spectrum on a frequency domain A compelling argument against narrowband transmission-other than the high peak power required to send it-is that narrow band signals can be jammed or experience interference very easily. Jamming is the intentional overpowering of a transmission using unwanted signals transmitted on the same band. Because its band is so narrow, other narrow band signals, including noise, can completely eliminate the information by overpowering a narrowband transmission; much like a passing train overpowers a quiet conversation. 2. 2. 3 Spread Spectrum Technology Spread spectrum technology allows taking the same amount of information than previously using a narrow band carrier signal and spreading it out over a much larger frequency range. For example, 1 MHz at 10 Watts with narrow band, but 20 MHz at 100 mW with spread spectrum. By using a wider frequency spectrum, we reduce the probability that the data will be corrupted or jammed. A narrow band jamming attempt on a spread spectrum signal would likely be thwarted by virtue of only a small part of the information falling into the narrow band signal' frequency range. s s Most of the digital data would be received error-free [4]. Today' spread spectrum RF radios can retransmit any small amount of data loss due to narrowband interference. While the spread spectrum band is relatively wide, the peak power of the signal is quite low. This is the second requirement for a signal to be considered spread spectrum. For a signal to be considered spread spectrum, it must use low power. These two characteristics of spread spectrum (use of a wide band of frequencies and very low power) make it look to most receivers as if it were a noise signal. Noise is a wide band, low power signal, but the difference is that noise is unwanted. Furthermore, since most radio receivers will view the spread spectrum signal as noise, these receivers will not attempt to demodulate or interpret it, creating a slightly more secure communication. 2. 2. 4 Frequency Hopping Spread Spectrum (FHSS) Frequency hopping spread spectrum is a spread spectrum technique that uses frequency agility to spread the data over more than 83 MHz. Frequency agility refers to the radio’s ability to change transmission frequency abruptly within the usable RF frequency band [4]. In the case of frequency hopping wireless LANs, the usable portion of the 2. GHz ISM band is 83. 5 MHz, per FCC regulation and the IEEE 802. 11 standard. 13 How FHSS Works In frequency hopping systems, the carrier changes frequency, or hops, according to a pseudorandom sequence. The pseudorandom sequence is a list of several frequencies to which the carrier will hop at specified time intervals before repeating the pattern. The transmitter uses this hop sequence to select it s transmission frequencies. The carrier will remain at a certain frequency for a specified time (known as the dwell time), and then use a small amount of time to hop to the next frequency (hop time). When the list of frequencies has been exhausted, the transmitter will repeat the sequence. Figure 2. 9 shows a frequency hopping system using a hop sequence of five frequencies over 5 MHz band. In this example, the sequence is: 1. 2. 449 GHz 2. 2. 452 GHz 3. 2. 448 GHz 4. 2. 450 GHz 5. 2. 451 GHz Figure 2. 9: Single frequency hopping system Once the radio has transmitted the information on the 2. 451 GHz carrier, the radio will repeat the hop sequence, starting again at 2. 449 GHz. The process of repeating the sequence will continue until the information is received completely. The receiver radio is synchronized to the transmitting radio' hop sequence in order to s receive on the proper frequency at the proper time. The signal is then demodulated and used by the receiving computer. Effects of Narrow Band Interference Frequency hopping is a method of sending data where the transmission and receiving systems hop along a repeatable pattern of frequencies together. As is the case with all spread spectrum technologies, frequency hopping systems are resistant-but not immune-to narrow band interference. In example in Figure 2. 9, if a signal were to interfere with our frequency hopping signal on, say, 2. 51 GHz, only that portion of the spread spectrum signal would be lost. The rest of the spread spectrum signal would remain intact, and the lost data would be retransmitted. 14 In reality, an interfering narrow band signal may occupy several megahertz of bandwidth. Since a frequency hopping band is over 83 MHz wide, even this interfering signal will cause little de gradation of the spread spectrum signal. Frequency Hopping Systems The IEEE and Open-Air standards regarding FHSS systems describe: 1. The frequency bands which may be used 2. Hop sequences 3. Dwell times 4. Data rates The IEEE 802. 1 standard specifies data rates of 1 Mbps and 2 Mbps and Open-Air (a standard created by the now defunct Wireless LAN Interoperability Forum) specifies data rates of 800 kbps and 1. 6 Mbps. In order for a frequency hopping system to be 802. 11 or Open-Air compliant, it must operate in the 2. 4 GHz ISM band (which is defined by the FCC as being from 2. 4000 GHz to 2. 5000 GHz). Both standards allow operation in the range of 2. 4000 GHz to 2. 4835 GHz. Channels A frequency hopping system will operate using a specified hop pattern called a channel. Frequency hopping systems typically use the FCC’s 26 standard hop patterns or a subset thereof. Some frequency hopping systems will allow custom hop patterns to be created, and others even allow synchronization between systems to completely eliminate collisions in a co-located environment. Figure 2. 10: Co-located frequency hopping system Though it is possible to have as many as 79 synchronized, co-located access points, with this many systems, each frequency hopping radio would require precise synchronization with all of the others in order not to interfere with (transmit on the same frequency as) another frequency hopping radio in the area. The cost of such a set of systems is prohibitive and is generally not considered an option. If synchronized radios are used, the expense tends to dictate 12 co-located systems as the maximum. 15 If non-synchronized radios are to be used, then 26 systems can be co-located in a wireless LAN; this number is considered to be the maximum in a medium-traffic wireless LAN. Increasing the traffic significantly or routinely transferring large files places the practical limit on the number of co-located systems at about 15. More than 15 co-located frequency-hopping systems in this environment will interfere to the extent that collisions will begin to reduce the aggregate throughput of the wireless LAN. Dwell Time In frequency hopping systems, it must transmit on a specified frequency for a time, and then hop to a different frequency to continue transmitting. When a frequency hopping system transmits on a frequency, it must do so for a specified amount of time. This time is called the dwell time. Once the dwell time has expired, the system will switch to a different frequency and begin to transmit again. Suppose a frequency hopping system transmits on only two frequencies, 2. 401 GHz and 2. 402 GHz. The system will transmit on the 2. 01 GHz frequency for the duration of the dwell time100 milliseconds (ms), for example. After 100ms the radio must change its transmitter frequency to 2. 402 GHz and send information at that frequency for 100ms. Hop Time When considering the hopping action of a frequency hopping radio, dwell time is only part of the story. When a frequency hopping radio jumps from frequency A to frequency B, it must change the transmit frequency in one of two ways. It ei ther must switch to a different circuit tuned to the new frequency, or it must change some element of the current circuit in order to tune to the new frequency. In either case, the process of changing to the new frequency must be complete before transmission can resume, and this change takes time due to electrical latencies inherent in the circuitry. There is a small amount of time during this frequency change in which the radio is not transmitting called the hop time. The hop time is measured in microseconds ( µs) and with relatively long dwell times of around 100-200 ms, the hop time is not significant. A typical 802. 11 FHSS system hops between channels in 200-300  µs. With very short dwell times of 500 – 600 µs, like those being used in some frequency hopping systems such as Bluetooth, hop ime can become very significant. If we look at the effect of hop time in terms of data throughput, we discover that the longer the hop time in relation to the dwell time, the slower the data rate of bits being transmitted. 2. 2. 5 Direct Sequence Spread Spectrum (DSSS) Direct sequence spread spectrum is very widely known and the most used of the spread spectrum types, owing most of its popularity to its ease of implementation and high data rates. The majority of wireless LAN equipment on the market today uses DSSS technology. DSSS is a method of sending data in which the transmitting and receiving systems are both on a 22 MHz-wide set of frequencies. The wide channel enables devices to transmit more information at a higher data rate than current FHSS systems. 16 How DSSS Works DSSS combines a data signal at the sending station with a higher data rate bit sequence, which is referred to as a chipping code or processing gain. A high processing gain increases the signal’s resistance to interference. The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20. The IEEE 802. 11 working group has set their minimum processing gain requirements at 11. The process of direct sequence begins with a carrier being modulated with a code sequence. The number of–chips-in the code will determine how much spreading occurs, and the number of chips per bit and the speed of the code (in chips per second) will determine the data rate. Direct Sequence Spread Spectrum (DSSS) Direct sequence spread spectrum is very widely known and the most used of the spread spectrum types, owing most of its popularity to its ease of implementation and high data rates. The majority of wireless LAN equipment on the market today uses DSSS technology. DSSS is a method of sending data in which the transmitting and receiving systems are both on a 22 MHz-wide set of frequencies. The wide channel enables devices to transmit more information at a higher data rate than current FHSS systems. How DSSS Works DSSS combines a data signal at the sending station with a higher data rate bit sequence, which is referred to as a chipping code or processing gain. A high processing gain increases the signal’s resistance to interference. The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20. The IEEE 802. 11 working group has set their minimum processing gain requirements at 11. The process of direct sequence begins with a carrier being modulated with a code sequence. The number of-chips-in the code will determine how much spreading occurs, and the number of chips per bit and the speed of the code (in chips per second) will determine the data rate. Channels Unlike frequency hopping systems that use hop sequences to define the channels, direct sequence systems use a more conventional definition of channels. Each channel is a contiguous band of frequencies 22 MHz wide and 1 MHz carrier frequencies are used just as with FHSS. Channel 1, for instance, operates from 2. 401 GHz to 2. 423 GHz (2. 412 GHz  ± 11 MHz); channel 2 operates from 2. 406 to 2. 429 GHz (2. 417  ± 11 MHz), and so forth. Figure 2. 11 illustrates this point. 17 Figure 2. 11: channel allocation and Spectral relationship The chart in Table 2. 1 has a complete list of channels used in the United States and Europe. The FCC specifies only 11 channels for non-licensed use in the United States. Each of the frequencies listed in this chart are considered center frequencies. From this center frequency, 11 MHz is added and subtracted to get the useable 22 MHz wide channel. Easy to see that adjacent channels (channels directly next to each other) would overlap significantly. Table 2. 1: DSSS channel frequency Assignment Channel ID 1 2 3 4 5 6 7 8 9 10 11 FCC Channel Frequencies GHz 2. 412 2. 417 2. 422 2. 427 2. 432 2. 437 2. 442 2. 447 2. 452 2. 457 2. 462 ETSI Channel Frequencies GHz N/A N/A 2. 422 2. 427 2. 432 2. 437 2. 442 2. 447 2. 452 2. 457 2. 462 To use DSSS systems with overlapping channels in the same physical space would cause interference between the systems. DSSS systems with overlapping channels should not be co-located because there will almost always be a drastic or complete reduction in throughput. Because the center frequencies are 5 MHz apart and the channels are 22 MHz wide, channels should be co-located only if the channel numbers are at least five apart: channels 1 and 6 do not overlap, channels 2 and 7 do not overlap, etc. There is a maximum of three co-located direct sequence systems possible because channels 1, 6 and 11 are the only theoretically non-overlapping channels. The 3 non-overlapping channels are illustrated in Figure 2. 2 18 Figure 2. 12: DSSS non-overlapping Channel 2. 2. 6 Comparing FHSS and DSSS Both FHSS and DSSS technologies have their advantages and disadvantages, and it incumbent on the wireless LAN administrator to give each its due weight when deciding how to implement a wireless LAN [4]. This section will cover some of the factors that should be discussed when determining which technology is appropriate f or your organization, including: 1. Narrowband interference 2. Co-location 3. Cost 4. Equipment compatibility 5. Data rate and throughput 6. Security 7. Standards support Narrowband Interference The advantages of FHSS include a greater resistance to narrow band interference. DSSS systems may be affected by narrow band interference more than FHSS because of the use of 22 MHz wide contiguous bands instead of the 79 MHz used by FHSS. This fact may be a serious consideration if the proposed wireless LAN site is in an environment that has such interference present. Co-location An advantage of FHSS over DSSS is the ability for many more frequency hopping systems to be co-located than direct sequence systems. Since frequency hopping systems are-frequency agile-and make use of 79 discrete channels, frequency hopping systems have a co-location advantage over direct sequence systems, which have a maximum co- location of 3 access points. 19 Figure 2. 13: Co-location Comparison However, when calculating the hardware costs of an FHSS system to get the same throughput as a DSSS system, the advantage quickly disappears. Because DSSS can have 3 co-located access points, the maximum throughput for this configuration would be: 3 access points ? 1 Mbps = 33 Mbps At roughly 50% of rated bandwidth, the DSSS system throughput would be approximately: 33 Mbps / 2 = 16. 5 Mbps To achieve roughly the same rated system bandwidth using an IEEE 802. 11 compliant FHSS system would require: 16 access points ? 2 Mbps = 32 Mbps At roughly 50% of rated bandwidth, the FHSS system throughput would be approximately: 32 Mbps / 2 = 16 Mbps In this configuration, an FHSS system would require 13 additional access points t o be purchased to get the same throughput as the DSSS system. Also, additional installation services for these units, cables, connectors, and antennas would all need to be purchased. Cost: When implementing a wireless LAN, the advantages of DSSS may be more compelling than those of FHSS systems, particularly when driven by a tight budget. The cost of implementing a direct sequence system is far less than that of a frequency hopping system. DSSS equipment is widely available in today’s marketplace, and its rapid adoption has helped in driving down the cost. Only a few short years ago, equipment was only affordable by enterprise customers. Today, very good quality 802. 11b compliant PC cards can be purchased for under $100. FHSS cards complying with either the 802. 11 or Open-Air standards typically run between $150 and $350 in today' market depending on the manufacturer and the standards to which the cards s adhere. 20 Equipment compatibility and availability The Wireless Ethernet Compatibility Alliance (WECA) provides testing of 802. 11b compliant DSSS wireless LAN equipment to ensure that such equipment will operate in the presence of and interoperate with other 802. 11b DSSS devices. The interoperability standard that WECA created and now uses is called Wireless Fidelity, or Wi-Fi, and hose devices that pass the tests for interoperability are-Wi-Fi compliant-devices. Devices so deemed are allowed to affix the Wi-Fi logo on the related marketing material and devices themselves showing that they have been tested and interoperate with other Wi-Fi compliant devices. There are no such compatibility tests for equipment that uses FHSS. There are standards such as 802. 11 and Open-Air, but no organization h as stepped forward to do the same kind of compatibility testing for FHSS as WECA does for DSSS. Due to the immense popularity of 802. 11b compliant radios, it is much easier to obtain these units. The demand seems only to be growing for the Wi-Fi compliant radios while the demand for FHSS radios has remained fairly steady, even decreasing to some degree over the past year. Data rate and throughput The latest frequency hopping systems are slower than the latest DSSS systems mostly because their data rate is only 2 Mbps. Though some FHSS systems operate at 3 Mbps or more, these systems are not 802. 11 compliant and may not interoperate with other FHSS systems. FHSS and DSSS systems have a throughput (data actually sent) of only about half of the data rate. When testing the throughput of a new wireless LAN installation, achieving 5-6 Mbps on the 11 Mbps setting for DSSS or 1 Mbps on the 2 Mbps setting common using DSSS. When wireless frames are transmitted, there are pauses between data frames for control signals and other overhead tasks. With frequency hopping systems, this interframe spacing is longer than that used by direct sequence systems, causing a slow-down in rate that data is actually sent (throughput). Additionally, when the frequency hopping system is in the process of changing the transmit frequency, no data is sent. This translates to more lost throughput, albeit only a minor amount. Some wireless LAN systems use proprietary physical layer protocols in order to increase throughput. These methods work, yielding throughputs as high as 80% of the data rate, but in so doing, sacrifice interoperability. Security: It is widely touted-and is a myth-that frequency hopping systems are inherently more secure than direct sequence systems. The first fact that disproves this myth is that FHSS radios are only produced by a minimal number of manufacturers. Of this small list of manufacturers, all of them adhere to standards such as 802. 1 or Open-Air in order to sell their products effectively. Second, each of these manufacturers uses a standard set of hop sequences, which generally comply with a pre-determined list, produced by the standards body (IEEE or WLIF). These 2 items together make breaking the code of hop sequences relatively simple. 21 Other reasons that make finding the hop sequence quite simple is that the channel number is broadcasted in the clear with each beacon. Also, the MAC address of the transmitting access point can be seen with each beacon (which indicates the manufacturer of the radio). Some manufacturers allow the administrator the flexibility of defining custom hopping patterns. However, even this custom capability is no level of security since fairly unsophisticated devices such as spectrum analyzers and a standard laptop computer can be used to track the hopping pattern of a FHSS radio in a matter of seconds. Standards Support: DSSS has gained wide acceptance due to low cost, high speed, WECA' Wi-Fi s interoperability standards, and many other factors. This market acceptance will only accelerate due to the industry moving toward newer, faster DSSS systems such as the new 802. 1g and 802. 11a compliant wireless LAN hardware. WECA' new Wi-Fi5 s interoperability standard for 5 GHz DSSS systems operating in the UNII bands will help move the industry along even faster in the same direction it is already headed. The new standards for FHSS systems include Home RF 2. 0 and 802. 15 (in support of WPANs such as Bluetooth), but none for advancing FHSS systems in the enterp rise. 2. 2. 7 BPSK In BPSK, the phase of the carrier is varied to represent binary 1 or 0 . Both peak amplitude and frequencies remain constant as the phase changes. For example, if a phase of 0 represents binary 0, then the phase 180 represents binary 1. the phase of the signal during each bit duration is constant. And its value depends on the bit (0 or 1). Figure 2. 14 shows a conceptual view of BPSK. BPSK is also known as 2-PSK. because two different phases (0 and 180) are used. The table below shows BPSK which makes the relationship of phase to bit value. Bit 0 1 Phase 0? 180? Figure 2. 14: BPSK. 2. 2. 8 QPSK The diagram for the signal is given in Figure 2. 15. A phase of 0 now represents 00; 90 represents 01; 180 represents10; and 270 represents 11. This technique is called QPSK. The pair of bits represented by each phase is called a dibit. 22 Bit 00 01 10 11 Figure 2. 15: QPSK. Phase 0? 90? 180? 270? 2. 2. 9 QAM QAM is a Combination of ASK and PSK so that a maximum contrast between each signal unit (bit, dibit, tribit, and so on) is achieved. QAM takes the advantages of the fact that it is possible to send two different signals simultaneously on the same carrier frequency . by using two copies of the carrier frequency. One shifted by 90 with respect to the other. For QAM, each carrier is ASK modulated. The two independent signals are simultaneously transmitted over the same medium. In QAM the number of amplitude shifts is fewer than the number of phase shifts. Because amplitude changes are susceptible to noise and require greater shift distances than do phase changes, the number of phase shifts used by a QAM system is always larger than the number of amplitude shifts. [5] Figure 2. 16: QAM. 23 2. 2. 10 Orthogonal Frequency division Multiplexing (OFDM) Orthogonal Frequency division Multiplexing offers the highest data rates and maximum resistance to interference and corruption of all the signal manipulation techniques in use in 802. 1 today [5]. Although it is not considered a spread spectrum technique by the FCC, OFDM shares many qualities with spread spectrum communicators, including using a low transmit power and wider-than-necessary bandwidth. OFDM is used to provide data rates up to 54 Mbps in 802. 11a and 802. 11g. How OFDM Works OFDM achieves high data rates by squeezing a large number of Communication Channels into a given frequency band. Normally, two c ommunication channels must be separated by a certain amount of bandwidth or they overlap and interfere. Specially, each Channel has harmonics that extend up and down the frequency space, decreasing in amplitude as they get farther from the channels fundamental signal. Even if two channels are non-overlapping, their harmonics may overlap and the signal can be corrupted. An OFDM communicator can place adjacent communication channels very precisely in the frequency space in such a way that the channels harmonics exactly cancel each other, effectively leaving only the fundamental signals. OFDM achieves high data rates by dividing a single communication channel into a large number of closely-spaced, small bandwidth sub-carriers. Each sub-carrier individually has a relatively low data rate, but by transmitting data in parallel on all sub-carriers simultaneously, high data rates can be achieved. Figure 2. 17: OFDM frequency plot. Figure 2. 17 shows an example of a frequency spectrum for an OFDM transmitter. Each of the peaks represents a single sub-carrier, and the sub-carriers together make up the communications channel. The sub-carriers are precisely aligned so that the zero-points of their harmonics overlapped exactly. The majority of the harmonic energy will cancel out, leaving just the sub-carriers. 4 CHAPTER 3 RF Antenna and Accessories 25 Chapter 3 RF Antenna and Accessories 3. 1 Introduction Antennas are most often used to increase the range of wireless LAN systems, but proper antenna selection can also enhance the security of your wireless LAN. A properly chosen and positioned antenna can reduce the signal leaking out of workspace, and make signal interception extremely difficult. 3. 2 RF Antennas An RF antenna is a device used to convert high frequency (RF) signals on a transmission line (a cable or waveguide) into propagated waves in the air [6]. The electrical fields emitted from antennas are called beams or lobes. Antenna convert electrical energy into RF waves in the case of a transmitting antenna, or RF waves into electrical energy in the case of a receiving antenna. The physical dimensions of an antenna, such as its length, are directly related to the frequency at which the antenna can propagate waves or receive propagated waves. The physical structure of an antenna is directly related to the Shape of the area in which it concentrates most of its related RF energy. There are three generic categories of RF antennas: 1. Omni-directional 2. Semi-directional 3. Highly-directional Each category has multiple types of antennas, each having different RF characteristics and appropriate uses. As the gain of an antenna goes up, the coverage area narrows so that high-gain antennas offer longer coverage areas than low-gain antennas at the same input power level. 3. 2. 1 Omni-directional (Dipole) Antennas The dipole is an omni- directional antenna, because it radiates its energy equally in all directions around its axis. Dipole antenna is Simple to design; dipole antenna is standard equipment on most access points. Directional antennas concentrate their energy into a cone, known as a â€Å"beam. † Figure 3. 1: Dipole doughnut 26 Figure 3. 1 shows that the dipole' radiant energy is concentrated into a region that s looks like a doughnut, with the dipole vertically through the â€Å"hole† of the â€Å"doughnut. † The signal from an omni-directional antenna radiates in a 360-degree horizontal beam. If an antenna radiates in all directions equally (forming a sphere), it is called an isotropic radiator, which is the theoretical reference for antennas, but rather, practical antennas all have some type of gain over that of an isotropic radiator. The dipole radiates equally in all directions around its axis, but does not radiate along the length of the wire itself – hence the doughnut pattern. The side view of a dipole radiator as it radiates waves in Figure 3. 2. Figure 3. 2: Dipole-side view If a dipole antenna is placed in the center of a single floor of a multistory building, most of its energy will be radiated along the length of that floor, with some significant fraction sent to the floors above and below the access point. Figure 3. 3 shows examples of some different types of omni-directional antennas. Figure 3. 3: Sample omni-directional antenna Figure 3. 4 shows a two-dimensional example of the top view and side view of a dipole antenna. Figure 3. 4: Coverage area of an omni-directional antenna High-gain omni-directional antennas offer more horizontal coverage area, but the vertical coverage area is reduced, as can be seen in Figure 3. 5. 27 Figure 3. 5: Coverage area of high gain omni-directional antennas This characteristic can be an important consideration when mounting a high-gain omni antenna indoors on the ceiling. If the ceiling is too high; the coverage area may not reach the floor, where the users are located. Usages Omni-directional antennas are used when coverage in all directions around the horizontal axis of the antenna is required. Omni-directional antennas are most effective where large coverage areas are needed around a central point. For example, placing an omni- directional antenna in the middle of a large, open room would provide good coverage. Omni-directional antennas are commonly used for point-tomultipoint designs with a hub-n-spoke topology. Used outdoors, an omni-directional antenna should be placed on top of a structure (such as a building) in the middle of the Figure 3. 6: Point to multipoint link coverage area. For example, on a college campus the antenna might be placed in the center of the campus for the greatest coverage area. When used indoors, the antenna should be placed at the middle of the building or desired coverage area, near the ceiling, for optimum coverage. Omni-directional antennas emit a large coverage area in a circular pattern and are suitable for warehouses or tradeshows where coverage is usually from one corner of the building to the other. 3. 2. 2 Semi directional Antenna Semi directional antennas direct the energy from the transmitter significantly more in one particular direction rather than the uniform circular pattern that is common with the omni- directional antenna; Semi-directional antennas come in many different styles and shapes. Some semi- directional antennas types frequently used with wireless LANs are Patch, Panel, and Yagi (pronounced â€Å"YAH-gee†) antennas. All of these antennas are generally flat and designed for wall mounting. Each type has different coverage characteristics. Figure 3. shows some examples of semidirectional antennas. 28 Figure 3. 7: Sample semi-directional antenna Semi-directional antennas often radiate in a hemispherical or cylindrical coverage pattern as can be seen in Figure 3. 8. Figure 3. 8: Coverage area of a semi-directional antenna Usages Semi-directional antennas are ideally suited for short and medium range bridging. For example, two office buildings that are across the street from one another and n eed to share a network connection would be a good scenario in which to implement semidirectional antennas. In a large indoor space, if the transmitter must be located in the corner or at the end of a building, a corridor, or a large room, a semi-directional antenna would be a good choice to provide the proper coverage. Figure 3. 9 illustrates a link between two buildings using semi-directional antennas. Figure 3. 9: Point to point link using semi-directional antenna In some cases, semi-directional antennas provide such long-range coverage that they may eliminate the need for multiple access points in a building. For example, in a long hallway, several access points with omni antennas may be used or perhaps only one or two access points with properly placed semi-directional antennas – saving the customer a significant amount of money. In some cases, semi- directional antennas have back and side lobes that, if used effectively, may further reduce the need for additional access points. 29 3. 2. 3 Highly directional antenna Highly-directional antennas emit the most narrow signal beam of any antenna type and have the greatest gain of these three groups of antennas. Highly-directional antennas are typically concave, dish-shaped devices, as can be seen Figures 3. 10 and 3. 11. These antennas are ideal for long distance, point-to-point wireless links. Some models are referred to as parabolic dishes because they resemble small satellite dishes. Others are called grid antennas due to their perforated design for resistance to wind loading. Figure 3. 10: sample of a highly directional antenna Figure 3. 11: sample of a highly directional grid antenna Figure 3. 12: Radiation pattern of a highly directional antenna Usages High-gain antennas do not have a coverage area that client devices can use. These antennas are used for point-to-point communication links, and can transmit at distances up to 25 miles. Potential uses of highly directional antennas might be to connect two buildings that are miles away from each other but have no obstructions in their path. Additionally, these antennas can be aimed directly at each other within a building in order to â€Å"blast† through an obstruction. This setup would be used in order to get network connectivity to places that cannot be wired and where normal wireless networks will not work. 0 3. 2. 4 Antenna Gain An antenna element without the amplifiers and filters typically associated with it is a passive device. There is no conditioning, amplifying, or manipulating of the signal by the antenna element itself. The antenna can create the effect of amplification by virtue of its physical shape. Antenna amplification is the result of focusing the RF ra diation into a tighter beam, just as the bulb of a flashlight can be focused into a tighter beam creating a seemingly brighter light source that sends the light further. The focusing of the radiation Measured by way of beam widths, which are measured in degrees horizontal and vertical. For example, an omni-directional antenna has a 360-degree horizontal beam width. By limiting the 360-degree beam width into a more focused beam of, say, 30 degrees, at the same power, the RF waves will be radiated further. This is how patch, panel, and Yagi antennas (all of which are semi-directional antennas) are designed. Highly directional antennas take this theory a step further by very tightly focusing both horizontal and vertical beam widths to maximize distance of the propagated wave at low power. . 2. 5 Intentional Radiator As defined by the Federal Communication Commission (FCC), an intentional radiator is an RF device that is specifically designed to generate and radiate RF signals. In terms of hardware, an intentional radiator will include the RF device and all cabling and connectors up to, but not including, the antenna, as illustrated in Figure 3. 13 below . Figure 3. 13: Intentional Radiator Any reference to â€Å"power output of the Intentional Radiator† refers to the power output at the end of the last cable or connector before the antenna. For example, consider a 30- milliwatt transmitter that loses 15 milliwatts of power in the cable and another 5 milliwatts from the connector at the antenna. The power at the intentional radiator would be 10 milliwatts. As an administrator, it is your responsibility to understand the FCC rules relating to Intentional Radiators and their power output. Understanding how power output is measured, how much power is allowed, and how to calculate these values are all covered in this book. FCC regulations concerning output power at the Intentional Radiator and EIRP are found in Part 47 CFR, 1 3. 2. 6 Equivalent Isotropically Radiated Power (EIRP) EIRP is the power actually radiated by the antenna element, as shown in Figure 3. 14. This concept is important because it is regulated by the FCC and because it is used in calculating whether or not a wireless link is viable. EIRP takes into account the gain of the antenna. Figure 3. 14: Equivalent Isotropically Radiated Power Suppose a transmittin g station uses a 10-dBi antenna (which amplifies the signal 10fold) and is fed by 100 mill watts from the intentional radiator. The EIRP is 1000 mW, or 1 Watt. The FCC has rules defining both the power output at the intentional radiator and the antenna element. 3. 3 RF Accessories When wireless LAN devices connect together, the appropriate cables and accessories need to purchase that will maximize throughput, minimize signal loss, and, most importantly, allow making connections correctly. Different types of accessories are needed in a wireless LAN design. [7] 1. RF Amplifiers 2. RF Attenuators 3. Lightning Arrestors 4. RF Connectors 5. RF Cables 3. 3. 1 RF Amplifiers An RF amplifier is used to amplify, or increase the amplitude of, RF signal, which is measured in +dB. An amplifier will be used when compensating the loss incurred by the RF signal, either due to the distance between antennas or the length of cable from a wireless infrastructure device to its antenna. Most RF amplifiers used with wireless LANs are powered using DC voltage fed onto the RF cable with an injector near the RF signal source (such as the access point or bridge). Sometimes this DC voltage used to power RF amplifiers is called â€Å"phantom voltage† because the RF amplifier seems to magically power up. This DC injector is powered using AC voltage from a wall outlet, so it might be located in a wiring closet. In this scenario, the RF cable carries 32 both the high frequency RF signal and the DC voltage necessary to power the in-line amplifier, which, in turn, boosts the RF signal amplitude. Figure 3. 15 shows an example of an RF amplifier (left), and how an RF amplifier is mounted on a pole (right) between the access point and its antenna. Figure 3. 15: A sample of a fixed gain Amplifier RF amplifiers come in two types: unidirectional and bi-directional. Unidirectional amplifiers compensate for the signal loss incurred over long RF cables by increasing the signal level before it is injected into the transmitting antenna. Bi-directional amplifiers boost the effective sensitivity of the receiving antenna by amplifying the received signal before it is fed into the access point, bridge, or client device. Configuration and Management RF amplifiers used with wireless LANs are installed in series with the main signal path seen below in Figure 3. 16. Amplifiers are typically mounted to a solid surface using screws through the amplifier’s flange plates. Configuration of RF amplifiers is not generally required unless the amplifier is a variable RF amplifier. If the amplifier is variable, the amplifier must be configured for the proper amount of amplification required, according to RF math calculations. The manufacturer' user manual will s explain how to program or configure the amplifier. Figure 3. 16: RF amplifier placement in the wireless LAN system 3. 3. 2 RF Attenuators An RF attenuator is a device that causes precisely measured loss (in dB) in an RF signal. While an amplifier will increase the RF signal, an attenuator will decrease it. Consider the case where an access point has a fixed output of 100mW, and the only antenna available is an omni-directional antenna with +20 dBi gain. Using this equipment together would violate FCC rules for power output, so an attenuator could be added to decrease the RF signal down to 30mW before it entered the antenna. This configuration would put the power output within FCC parameters. Figure 3. 17 shows examples of fixed-loss RF attenuators with BNC connectors (left) and SMA connectors (right). Figure 3. 18 shows an example of an RF step attenuator. 33 Figure 3. 7: Sample of a fixed loss Amplifier Figure 3. 18: A sample of a RF step attenuator (Variable loss) Configuration and Management Figure 3. 19 shows the proper placement in a wireless LAN for an RF attenuator, which is directly in series with the main signal path. Fixed, coaxial attenuators are connected directly between any two-connection points between the transmitter and the antenna. For example, a fixed, coaxial antenn a might be connected directly on the output of an access point, at the input to the antenna, or anywhere between these two points if multiple RF cables are used. Variable antennas are generally mounted to a surface with screws through their flange plates or simply placed in a wiring closet on a shelf. Configuration of RF attenuators is not required unless a variable attenuator is used, in which case, the amount of attenuation required is configured according to your RF calculations. Configuration instructions for any particular attenuator will be included in the manufacturer' user manual. s Figure 3. 19: RF attenuator placement in a wireless LAN 3. 3. 3 Lightning Arrestors A lightning arrestor is used to shunt transient current into the ground that is caused by lightning. Lightning arrestors are used for protecting wireless LAN hardware such as access points, bridges, and workgroup bridges that are attached to a coaxial transmission line. Coaxial transmission lines are susceptible to surges from nearby lightning strikes. Lightning arrestor are only needed for outdoor antennas that are 34 Susceptible to lighting sticks in the vicinity. They are not necessary for indoor antennas because of the existing building ground. A lightning arrestor can generally shunt surges up to 5000 Amperes at up to 50 volts. Lightning arrestor performs the following function 1. Lightning strikes a nearby object 2. Transient current are induced in the antenna or the RF transmission line 3. The lightning arrestor senses these currents and immediately ionizes the gases held internally to cause a short (a path of almost no resistance) directly to earth ground. Figure 3. 20: Lightning Arrestors installed in a network 3. 3. 4 RF Connectors RF connectors are specific types of connection devices used to connect cables to devices or devices to devices. Traditionally, N, F, SMA, BNC, and TNC connectors (or derivatives) have been used for RF connectors on wireless LANs. In 1994, the FCC and DOC (Canadian Department of Communications) ruled that connectors for use with wireless LAN devices should be proprietary between manufacturers [7]. For this reason, many variations on each connector type exist such as: 1. N-type 2. Reverse polarity N-type 3. Reverse threaded N-type Figure 3. 21: Sample N-type and SMA Connector 35 Choosing an RF Connector There are five things that should be considered when purchasing and installing any RF connector, and they are similar in nature to the criteria for choosing RF amplifiers and attenuators. . The RF connector should match the impedance of all other wireless LAN components (generally 50 ohms). 2. Know how much insertion loss each connector inserted into the signal path causes. The amount of loss caused will factor into your calculations for signal strength required and distance allowed. 3. Know the upper frequency limit (frequency response) specified for the particular connectors. This point will be very important as 5 GHz wireless LANs become more and more common. Some connectors are rated only as high as 3 GHz, which is fine for use with 2. GHz wireless LANs, but will not work for 5 GHz wireless LANs. Some connectors are rated only up to 1 GHz and will not work with wireless LANs at all, other than legacy 900 MHz wireless LANs. 4. Beware of bad quality connectors. First, always consider purchasing from a reputable company. Second, purchase only high-quality connectors made by name-brand manufacturers. This kind of purchasing particularity will help eliminate many problems with sporadic RF signals, VSWR, and bad connections. 5. Make sure you know both the type of connector (N, F, SMA, etc. ) that you need and the sex of the connector. Connectors come in male and female. Male connectors have a center pin, and female connectors have a center receptacle. 3. 3. 5 RF Cables Proper cables are needed for connecting an antenna to an access point or wireless bridge. Below are some criteria to be considered in choosing the proper cables for your wireless network. 1. Cables introduce loss into a wireless LAN, so make sure the shortest cable length necessary is used. 2. Plan to purchase pre-cut lengths of cable with pre-installed connectors. Doing minimizes the possibility of bad connections between the connector and the cable. Professional manufacturing practices are almost always superior to cables manufactured by untrained individuals. 3. Look for the lowest loss cable available at your particular price range (the lower the loss, the more expensive the cable). Cables are typically rated for loss in dB/100-feet. The table in Figure 5. 29 illustrates the loss that is introduced by adding cables to a wireless LAN. 4. Purchase cable that has the same impedance as all of your other wireless LAN components (generally 50 ohms). 5. The frequency response of the cable should be considered as a primary decision factor in your purchase. With 2. 4 GHz wireless LANs, a cable with a rating of at least 2. 5 GHz should be used. With 5 GHz wireless LANs, a cable with a rating of at least 6 GHz should be used. 36 Table 3. 1: Coaxial Cable attenuation ratings LMR Cable 100A 195 200 240 300 400 400UF 500 600 600UF 900 1200 1700 30 3. 9 2. 0 1. 8 1. 3 1. 1 0. 7 0. 8 0. 54 0. 42 0. 48 0. 29 0. 21 0. 15 50 5. 1 2. 6 2. 3 1. 7 1. 4 0. 9 1. 1 0. 70 0. 55 0. 63 0. 37 0. 27 0. 19 150 8. 9 4. 4 4. 0 3. 0 2. 4 1. 5 1. 7 1. 2 1. 0 1. 15 0. 66 0. 48 0. 35 220 10. 9 5. 4 4. 8 3. 7 2. 9 1. 9 2. 2 1. 5 1. 2 1. 0. 80 0. 59 0. 43 450 15. 8 7. 8 7. 0 5. 3 4. 2 2. 7 3. 1 2. 2 1. 7 2. 0 1. 17 0. 89 0. 63 900 22. 8 11. 1 9. 9 7. 6 6. 1 3. 9 4. 5 3. 1 2. 5 2. 9 1. 70 1. 3 0. 94 1500 30. 1 14. 5 12. 9 9. 9 7. 9 5. 1 5. 9 4. 1 3. 3 3. 8 2. 24 1. 7 1. 3 1800 33. 2 16. 0 14. 2 10. 9 8. 7 5. 7 6. 6 4. 6 3. 7 4. 3 2. 48 1. 9 1. 4 2000 35. 2 16. 9 15. 0 11. 5 9. 2 6. 0 6. 9 4. 8 3. 9 4. 5 2. 63 2. 0 1. 5 2500 39. 8 19. 0 16. 9 12. 9 10. 4 6. 8 7. 8 5. 5 4. 4 5. 1 2. 98 2. 3 1. 7 37 CHAPTER 4 Wireless LAN 38 Chapter 4 Wireless LAN 4. 1 Wireless LAN (WLAN) 4. 1. 1 Wireless LAN Linking of t