Advertisement from 1925 and 1927 Essay Example | Topics and Well Written Essays - 250 words

Promotion from 1925 and 1927 - Essay Example Because of large scale manufacturing, the idea of showcasing of customer products started to develop. In this way, enormous associations began to showcase their items through commercials. The instances of the notices from 1925 to 1927 are: notice for Berkey and Gay Furniture Company (1925) and promotion for Eveready Flashlight and Battery (1927). Both the promotions are written in the style of a story in which the item and its aces have been portrayed. These promotions show that clients were persuaded about the utility of the item through a situation which speaks to the utilization of the item. The client would think about the items through the promotions which would show up in the papers and divider banners. The promotions are written in such a way, that the clients would peruse them alongside the remainder of the articles. The clients would think about the promotions since they give a sensible situation and they would constrain the client to consider the item. Subsequently, it tends to be inferred that the pattern of ads in 1920s was activated by the fast financial and social change. The instances of the notices gave above show that the ads were introduced as short stories which pulled in the consideration of the clients due to their practical

Na Essay Example | Topics and Well Written Essays - 750 words

Na - Essay Example At the point when the narratives start, the general impression a peruser gets is that the ladies were dedicated to their spouses. For example, in the Yellow Wallpaper, the hero in alluding to her significant other states, â€Å"He is cautious and cherishing and barely lets me mix without extraordinary direction.†(Gilman) For the situation of â€Å"The Hour†, Mrs. Maillard at first shows up heart broken at the updates on her husband’s passing †â€Å"she sobbed on the double, with unexpected wild surrender, in her sister’s arms.† (Chopin). In any case, as the accounts progress, this general impression is gave a false representation of. The hero in â€Å"The Yellow Wall Paper† displays an inconspicuous discontent with her better half John; he chuckles at her and the creator satirically comments â€Å"one expects that in marriage.†(Gilman). Besides, in spite of being a doctor, he doesn't accept she is debilitated, he has not let her take the room down the stairs with roses; rather he has kept her in a live with shocking yellow backdrop. It is additionally clear that the creator feels regretful about these inconspicuous, basic sentiments of outrage and disdain against her better half and would not be slanted to voice them so anyone might hear to anybody. She reprimands him for the way that she is wiped out and feels vulnerable on the grounds that regardless of being a doctor, he has portrayed her ailment as a negligible apprehensive sorrow and his assertion is law. She concedes, â€Å"I get absurdly irate with John now and again I’m sure I never used to be so sensitive.† This uncovers she k nows about fundamental sentiments of disdain, yet attempts to cover it as an undesirable symptom of her ailment. As a lady, she is relied upon to be agreeable and consign herself to home and hearth, living in acquiescence to her husband’s will and as the story advances, her outrage against her better half turns out to be increasingly clear. In â€Å"the Hour† the hero has been living for such a long time in the condition of bondage to her husband’s territory that she naturally

November 2014 Admissions Thoughts - UGA Undergraduate Admissions

November 2014 Admissions Thoughts - UGA Undergraduate Admissions November 2014 Admissions Thoughts We have made it past the Early Action decisions, and we are now at the next stages of the admission cycle. With that in mind, here are a few thoughts about what happens in Admissions and UGA from November to late March. Scholarships-We are working on the review of files for scholarships, but as of today we have only had about four working days since decisions were released, and most of those were spent talking with families. I expect that we will begin releasing some scholarship offers in mid-December, and this will continue until mid-April as we review files for different scholarships. We will offer about 15-20% of admitted students scholarships overall, but it takes time. Honors-The Honors program is working with our office to collect data on the admitted EA applicants, so please be patient with this office as they begin their review for their early offers. They hope to be able to start communicating with students in mid-December, but that is an estimate, not a specific timeline. Deferred EA applicants are beginning to submit part II of the application and get in teacher recommendations, and we expect the majority will finish these steps during the December holidays. Deferred applicants do not need to submit a new application or pay a new application fee, and it will cause problems for applicants who try to do this. In addition, the last section of part II is for any updates, where an applicant can give us new information such as updated activities, fall grades, new honors, etc. I also suggest that all RD and deferred EA applicants review the Timeline page for details on when we release decisions. While Fall grades are not required for RD or deferred EA applicants, I heavily suggest sending them in, either self-reported on part II or on a transcript. Accepted students do not need to send us updated grades unless requested by another office (Honors for instance). There are too many RD applicants and deferred EA applicants for us to recalculate every GPA with new grades, but senior grades are used in our holistic read process, and we do look at them carefully. For RD applicants, it is best to apply first and then send in any school documents, as it is easier and quicker to match these items. Test scores can come in prior to applying without issue, but documents have to be saved in our holding files and then matched every day, and these files get a little overwhelming during deadline times with thousands of non-matched documents. During your senior year, do not catch senioritis or do something that you will regret the next day. The main reason we would ever rescind an admission offer would be a serious drop in grades or a problematic conduct issue, so stay strong and focused. This is also not the time to start to drop challenging courses for spring term. If we admitted you, it was in part based on the strength of your core classes. As such, we want to see you continue to challenge yourself in the courses you are in. We are fine if you need to change from PE to Health, or from one similar class to another, but we dont want to see you suddenly dropping AP Calc, AP Physics, etc. just to have an early release period. Remember, more is not always better. If you have ten teacher recommendations sent to us, or decide you need to send us a five page resume, or decide that the word short answer limits are too limiting and decide to send us two page essays by mail, know that it becomes harder to see the forest through the trees. Brevity and being concise are not bad things. We will accept SAT/ACT scores from exams taken and requested to be sent by the end of January. Please make sure you request your scores be sent to UGA when you sign up for the exam. Do not wait until you have seen your January scores before requesting them to be sent, as that might be too late. Remember, we only use the highest scores, so there is no need to wait before sending them. We are often asked about what teacher to select for a recommendation. We do not need a teacher who is a UGA alum, a department head, a person who has taught for 30+ years, or any other designation. Select a teacher who knows you well and can tell us what you are like as a person. Remember to check your myStatus page to make sure we have everything we need for admissions. The worst calls/emails are the ones where we have to say we could not make a decision due to an incomplete file. As well, re-review the Top 10 Urban Legends for UGA Admissions, as odd myths start to appear after EA decisions are released. Go Dawgs!

Privacy on the Internet - 1616 Words

Privacy on the Internet Ever feel like you are being watched? How about having the feeling like some one is following you home from school? Well that is what it will be like if users do not have the privacy on the Internet they deserve. EPIC (Electronic Privacy Information Center), a advocacy group that has been fighting the Clinton Administration for tougher online consumer protection laws, and other privacy protection agencies have formed to protect the rights and privileges of the Internet user. With the U.S. Government, EPIC has had to step in and help small companies and Internet users with their own privacy problems, hackers getting into their systems and ruining the networks, and crackers stealing and decrypting private†¦show more content†¦Once you could not even dream of putting your credit card on the Internet, but now with the invention of the secure line and encryption capabilities people or now using the internet to buy more than ever. You can now bank onli ne or buy stocks online if you want to, but with all of these new privacy inventions there are always the hackers inventions. Hackers have invaded the privacy of the American Internet User since the dawn of the Internet. With the protection programs that we write, the hackers write their own programs to disregard our individual privacy on the Internet and hack into systems holding our private information and stealing it to reveal some of our most biggest secrets. Encrypting private information has also been a useful tactic against hackers cracking encrypted data, and reading this private information. But they have their own ways of cracking our data. It was only not long ago that we could only encrypt up to 32-bit, and now we can encrypt up to 128-bit which makes it slightly impossible to decrypt unless you have almost all of your life to spend on solving it. But soon hackers will probably write bigger and more complex programs to decrypt this 128-bit shell that we have and ma ke that shell keep on going rising and rising in the numbers until not even a computer program or any hacker can access or private documents or files except us. The war on hackers isShow MoreRelatedInternet Privacy And The Internet1895 Words   |  8 PagesInternet privacy is an issue that has constantly taken up a portion of the world stage for many years. Legislators are even now trying to find the delicate balance between Internet privacy and Internet security. The medium of the Internet is simply too new to be completely understood by lawmakers, and it will take some time before there is a complete grasp. Online Privacy and Facebook Nowadays, the new generation life without Facebook is almost unthinkable. Since its inception in 2004, this popularRead MoreInternet Privacy.1148 Words   |  5 PagesSolutions for Violations of Internet Privacy. In the past thirty years computer technology has been developing very rapidly. Internet in last decade has revolutionized the way how we conduct our lives and businesses. Internet has become a daily necessity we cannot live without. Development of Internet and wireless technologies together with advancement in miniature technology has made it possible for us to have access the internet on the go. Every year we expect new and more advance modelsRead MoreThe Privacy Of The Internet1737 Words   |  7 PagesIf a casual user of the internet were to Google a search for the word â€Å"privacy† as of June 2015, there would be close to 2 billion hits. Discussions of privacy, piracy and internet breaches are everywhere. The numerous Google hits show there is nearly universal agreement that (1) we have less privacy and more information than we used to, and (2) this is bad.Information itself is, of course, not bad, but as we have witnessed recently, even personnel record maintained by the United States governmentRead MoreInternet Privacy And The Internet954 Words   |  4 Pagesunauthorized information by computer, but they actually make the internet a safer place. With the growth of the internet comes the growth of hackers and internet privacy. New laws that would increase internet privacy and, limit hackers would halt the internets growth and development. Since the year 2000, the internet has grown enormously we can all agree and with this growth comes a growth of internet users. With all the internet users, online comes people trying to accuse their information byRead More Essay on Internet Privacy - Invasion of Privacy on the Internet964 Words   |  4 PagesInvasion of Privacy on the Internet       Invasion of privacy is a serious issue concerning the Internet, as e-mails can be read if not encrypted, and cookies can track a user and store personal information. Lack of privacy policies and employee monitoring threatens security also. Individuals should have the right to protect themselves as much as possible from privacy invasion and shouldnt have to give in to lowered standards of safety being pursued by the government.    EncryptionRead MoreInternet Privacy1375 Words   |  6 PagesA Right to Privacy? What a Joke! It has become a sad and upsetting fact that in todays society the truth is that the right to ones privacy in the I.T (information technological) world has become, simply a joke. In an electronic media article No place to hide, written by James Norman, two interesting and debatable questions were raised: ‘Are we witnessing the erosion of the demarcation of public and private spaces brought on by the networked economy and new technology? Also, ‘What rolesRead MoreInternet Privacy1946 Words   |  8 PagesInternet Privacy The concern about privacy on the Internet is increasingly becoming an issue of international dispute. ?Citizens are becoming concerned that the most intimate details of their daily lives are being monitored, searched and recorded.? (www.britannica.com) 81% of Net users are concerned about threats to their privacy while online. The greatest threat to privacy comes from the construction of e-commerce alone, and not from state agents. E-commerce is structured on the copy andRead More Essay on Internet Privacy - Cookies and Privacy on the Internet1385 Words   |  6 PagesCookies: Privacy on the Internet?      Ã‚   Today, many web sites on the internet can use cookies to keep track of passwords and usernames and track the sites a particular user visits (Cookiecentral.com). But, the use of cookies to track users browsing habits is becoming a concern of many internet users. These concerned people are beginning to think of cookies as an invasion of privacy. Companies with web sites can use cookies to track what sites you visit frequently and then select specificRead MoreInternet Privacy : An Analysis Of The Internet1380 Words   |  6 PagesInternet Privacy: An Analysis of â€Å"The Internet is a Surveillance State† Since its inception in the late 1960s, the internet has changed the expansion of communications to new levels. Facebook, Twitter, Linkedin and many others have provided the public with means of communication. The sharing of photos, thoughts and even ideas has become a more prevalent event for everyone as time has progressed. Computers, tablets, and phones are used widely each day for social media sites, as well as purchasingRead More Privacy On The Internet Essay1588 Words   |  7 Pages Privacy on the Internet nbsp;nbsp;nbsp;nbsp;nbsp;Ever feel like you are being watched? How about having the feeling like some one is following you home from school? Well that is what it will be like if users do not have the privacy on the Internet they deserve. EPIC (Electronic Privacy Information Center), a advocacy group that has been fighting the Clinton Administration for tougher online consumer protection laws, and other privacy protection agencies have formed to protect the rights and

Sarah Louise s Relationship Between Race, Class And...

Even though a hundred years is just a blip in time on the cosmic scale, living from 1889 to 1999, as Sarah Louise Sadie Delany did, is not something to be overlooked. In fact, Sadie and her younger sister Annie Elizabeth Delany’s (also known as Bessie) total age was 213 years old! That is incredibly aspiring, given the fact that these two women witnessed a century of oppression and subjugation. Having Our Say is the story of these remarkable sisters, with the opening of the film showing us the sisters as old women in 1991 and then flashing back to their early lives in chronological order. Starting from their early childhood in Raleigh, North Carolina, this biographical film explores the relationship between race, class and gender and how each aspect influenced the sister’s lives for better or for worse. Throughout their lives, Bessie and Sadie Delany experienced various forms of oppression for firstly, being black and secondly, for being women. The description above refers to the term ‘intersectionality’. Intersectionality is a feminist sociological theory that seeks to examine how various cultural categories such as gender, race, and class contribute to social inequality. In the article Intersectionality Feminism, the author Anna Carastathis, brings up Kimberlà © Williams Crenshaw, the theorist who coined this ever inclusive term. She states how, â€Å"In the 1980s, Crenshaw was trying to understand why US anti-discrimination law was failing to protect Black women in theShow MoreRelatedGender And Racial Identity Of Film2128 Words   |  9 PagesYue Zheng Prof. Aili Bresnahan PHL 324 11/8/2016 Gender and Racial Identity in Film Gender and racial identity was a form of discrimination in the world and they were interrelated that fuelling the injustice social phenomenon and problem. For example, women were a particular group and as a symbol showed the social abuses, acts of violence and biggest discrimination based on the sexual difference and racism. The difference of color, race, gender were the big biases not only to deprive of women’sRead MoreThe Uncanny, A Freudian Term, By Sigmund Freud1993 Words   |  8 Pagesideas of Ernst Jentech, and Sigmund Freud, it is defined. Between them the uncanny is described as ...intellectual uncertainty; so that the uncanny would always, as it were, be something one does not know one’s way about in. The better oriented in his environment a person is, the less readily will he get the impression of something uncanny in regard to the objects and events in it. In Freud’s essay he states that â€Å"the â€Å"uncanny† is that class of the terri fying which leads back to something long knownRead MoreWho Are You Calling Old? 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The article concludes with a disJana Spilkovà ¡, Lucie Radovà ¡: The Formation of Identity in Teenage Mall Microculture 567 cussion of the main fi ndings on the attractiveness of shopping malls for teenagersRead MoreChildrens Literature13219 Words   |  53 Pagescategory; rather, it is a diverse and paradoxical area of study. Its richness is reflected in the vast amount of theories that permeate and surround the term. From feminist studies to new historicism, literary theory places the child/text/context relationship on varying ideological and political axes. The reconceptualization of its history and the postmodern growth of radical alternative literary â€Å"histories† further complicate a retelling of the history of children’s literature. Consequently, it becomesRead MoreLogical Reasoning189930 Words   |  760 Pagesemphasis right. Norman Swartz, Simon Fraser University v Acknowledgments For the 1993 edition: The following friends and colleagues deserve thanks for their help and encouragement with this project: Clifford Anderson, Hellan Roth Dowden, Louise Dowden, Robert Foreman, Richard Gould, Kenneth King, Marjorie Lee, Elizabeth Perry, Heidi Wackerli, Perry Weddle, Tiffany Whetstone, and the following reviewers: David Adams, California State Polytechnic University; Stanley Baronett, Jr., University

Western European History Free Essays

Western European history dates back to the time of the very first evidence of Homo sapiens in the regions during Paleolithic times, to the Neolithic, and then the Bronze Age, during which man was better developed and civilizations shaped, to the Christian Era when Christianity was formed and gained popularity, and Churches gained in power, to the time of the colonization, to the time of the famed Industrial Revolution when the modern day economy based on manufacture and trade came into being, to the present day western Europe. Historical evidence points to the fact that in ancient times, that is, the Paleolithic times of man, there exited several developed civilizations in different parts of the world. The Cro-Magnons were people, who lived during these times, and according to archaeologist Carleton Coon, the Cro-Magnon man was large, heavy boned and muscular in appearance, and he also had a powerful jaw and an inordinately large head. We will write a custom essay sample on Western European History or any similar topic only for you Order Now (Leonard R Cedric) One must remember the fact that Cro-Magnon is the term used by historians to describe the people who lived during the Ice Ages, and according to archaeologists, the physical dimensions of these ancient people were not sufficiently different from modern man to warranty a separate term, and therefore, they could be referred to as ‘AMH’s’, or ‘Anatomically Modern Humans’. Life for the common Cro-Magnon would not have been too simple; he had to hunt for his food with crudely made implements like the Aurignacian blades, as archaeologists refer to them. These were long slivers of stones sharpened to a knife like point, which would then be converted into all types of hunting tools. The Atlatl, a sophisticated hunting tool with a short dart and a pocket into which the dart would be fitted, was also used by these people, The Cro-Magnons lived civilized lives, and this is a fact that can be exemplified by the discovery of a child’s body before it was interred in a sophisticated burial ritual, about 24,000 years before today. (Hirst, Kris, K n. ) They used sophisticated shelters as well, and wore refined tailored clothing made out of animal skins, and jewelry carved out of stone and animal bone and teeth. Historians often state that this was a period of cultural florescence in the history of man. (Stone, Linda 2007) However, historians also state that one of the most far reaching and transformational influences of human culture that have ever taken place in the history of man is the Industrial Revolution that took place in eightee nth century Europe. The direct consequences of this revolution would have such an impact on human labor, consumption, social structure and even on the thoughts of man that it could be stated that the world would have been a different place today if the Industrial Revolution had never taken place when it did. It is important to remember that this revolution did not just happen overnight; it took place gradually over a period of time, with changes taking place all over the world in small doses, these changes influencing the basic social structure of man at the time. With the coming of the Industrial Revolution, however, Europe, as well as other parts of the world, was able to move from being a primarily agricultural economy to an industry based urban economy. The structure of the family, the social obligations that had to be fulfilled and so on brought about such great change to man that even today, one has not been able to come to terms with them fully. The European economy at the time of the Industrial Revolution had become a sort of global economy, with European trade and manufacture extending to several continents close to home, except Antarctica. The demand for European goods grew as Europeans started selling in foreign markets, and this made the conversion of Europe from an agricultural economy to an industrial manufacturing economy complete. Europe became one of the top world players in international markets. Life for the common man was however an entirely different issue. The social system was not adequate enough to provide for the rapid changes taking place, and as a result, the fast increasing population was growing increasingly confused. Business was based on exclusive monopoly, and as a consequence, many people were out of jobs. â€Å"The Industrial Revolution† n. d) Furthermore, the new factory system reduced free man to virtual slavery, and he became poorer than ever before; he could barely subsist on his wages. It even destroyed family life, and health and well being of the people. (Mises von Ludwig 1993) To conclude, it could be said that the life of common man is always at risk of being exposed to and influ enced by the changes taking place in society; neither do they possess the wealth nor do they have the expertise with which to deal with the situation in an effective manner. It is the life of common man that is subjected to the greatest changes in a country, and as exemplified by the life of the Cro-Magnon as well as the common man during the Industrial Revolution, he was forced to undergo several changes, and bear the consequences on himself, his wealth, his welfare, and his relationships. This is the way of the world, and one cannot avoid these changes as they occur; one must learn to accept them and deal with them as one sees fit, or else, suffer the dire consequences. Works Cited Leonard R Cedric â€Å"An Atlantean Outpost† (2006) Retrieved on December 15 2008 from: http://www.atlantisquest.com/Outpost.html Hirst, Kris, K â€Å"Why don’t we call them Cro-Magnons any more?† (n.d) Retrieved on December 15 2008 from: http://archaeology.about.com/od/earlymansites/a/cro_magnon.htm Stone, Linda â€Å"Genes, Culture and Human Evolution† (2007) Google Book Search Retrieved on December 15 2008 from: http://books.google.co.in/books?id=zdeWdF_NQhECpg=PA43lpg=PA43dq=Cro-Magnons+in+Paleolithic+Europesource=blots=wbEgEGkAGQsig=2HL9EByPHFl_J804fGJ5SnGxk78hl=ensa=Xoi=book_resultresnum=4ct=result Mises von Ludwig â€Å"Facts about the Industrial Revolution† (1993) Retrieved on December 15 2008 from: http://www.fff.org/freedom/0993e.asp â€Å"The Industrial Revolution† The European Enlightenment (n.d) Retrieved on December 15 2008 from: http://www.wsu.edu/~dee/ENLIGHT/INDUSTRY.HTM How to cite Western European History, Papers

The Circus Essay Sample free essay sample

As clip passed. everyone became more dying for the show to get down. I look about at the craze of the crowd. filled with many people of all ages. Siting front row. I wait impatiently. grinning from ear to ear. Just so the visible radiations dim. and the degree of my exhilaration increases vastly. it’s eventually clip ; the circus has begun! A topographic point visible radiation comes on and Begins traveling rapidly in every which manner. A man’s deep voice comes over the talkers. â€Å"Ladies and Gentlemen. delight take your seats. We welcome you all to the circus and hope you enjoy the show† . Once the announcer had finished. the topographic point light zeroed in on centre phase. where a big gold king of beasts sat. Hearing the cleft of a whip. a really tall skinny adult male walks into the now turning topographic point visible radiation. Another smack of the leather whip is released by the tamer and the slayer animal opens his tremendous oral cavity and lets out a great boom. We will write a custom essay sample on The Circus Essay Sample or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The crowd begins to hearten aloud. The adult male so guides the king of beasts through legion Ag basketballs. which amazes everyone including myself. After a few more fast ones. the king of beasts tamer takes a bow and both he and the king of beasts walk side by side off phase. Following the lion’s act. two adult females dressed in bluish beady frocks appear on the trapeze. Very high in the air and with no net about to catch them if they fell. I watch mesmerized with every somersault and turn made. cognizing the littlest error would be them their modus operandi. Next was an dumbfounding contortionist. In complete silence everyone tickers as their heads are blown by the bending and show of such unusual and alone flexibleness. When each act ended. I applaud for the unbelievable public presentations. Just so I smell popcorn popping. elephantine pes long hot Canis familiariss grilling. and conceive of the cotton confect being spun. It seemed as joy and amusement rapidly got the best of me and before I knew it. the first half of the show had finished. Smelling the mouthwatering nutrient. it wasn’t long before everyone could no longer strip their hungriness. On the 15 minute intermission. the nutrient booths were filled rapidly with people stuffing their faces with downy pink and bluish cotton confect that melted as it touched their linguas. and popcorn that left everybody’s custodies greasy from the sum of butter on every piece. The faces of the crowd displayed merry and pleasance with the exceeding nutrient they had purchased. Intermission passed so rapidly. it hadn’t felt anyplace near 15 proceedingss and the circus started up once more instantly. While the dark progressed. I find the public presentations more entertaining. Silly clowns with colossal ruddy olfactory organs and banging places were siting in autos much excessively little for them. Elephants danced. blades were swallowed. and a adult male was shot out of a cannon. Following the expansive coda. all the performing artists were brought to the phase to bow to the bright crowd. still full of exhilaration and ginger. I stood to demo to my grasp to the performing artists who arranged a fantastic and unforgettable show that was perfect for everyone who had come.

Images Of Women Essays - British People, Literature, Eliot Family

Images Of Women Images of Women: Major Barbara, A Passage to India, and the poetry of T.S. Eliot The Victorian Era was a difficult and confusing time for women, and their trials are reflected in the literature of the time. Although the three pieces of literature being discussed are not entirely about women, they shed light on the Victorian ideal of women and the ideals of the authors who created these women characters. In contrasting and comparing women in Major Barbara, A Passage to India, and T.S. Eliot's poetry, two key points will be discussed: distinct archetypes of women, and how the "absence" of women is used to signify their importance. There are four different archetypes of women present in the three works [1], the first being the heroines. The heroines are characterized by their success in dealing with the limitations of spiritual and physical matters, eventually accepting these limitations or reconciling their differences into their lives. Mrs. Moore is the heroine of A Passage to India. She is depicted as a heroine because of a small event that does not concern her personally. She comes to India just to further the happiness of her children, and due to the circumstances, sacrifices the integrity of her own self. She is at first very compassionate, with a love that extends over all creation, religion, and every living thing. (Shahane 29) She lives in a world where everything is in harmony, until her perfect vision is shattered by her experience in the Marabar Caves. After she enters the cave, Mrs. Moore hears an echo, which seems to whisper, "Everything exists, nothing has value." [2] Collier 2 This seems to rob Mrs. Moore of everything she holds valuable; her spiritual life and her relationships with family and friends. (Shahane 87) Everything has lost its meaning. Mrs. Moore finally sees all the troubles in the world, and how insignificant the world is. Despite her negative outlook after the Marabar Caves incident, Mrs. Moore accepts these realizations into her life. She breaks off relationships with her family and friends because she can no longer pretend that these relationships can exist with no meaning. She concerns herself with only trivial things, such as playing cards. In Major Barbara, the heroine is Major Barbara herself. She has more typical characteristics of a heroine than does Mrs. Moore. Shaw presents Barbara to us as a strong-willed, compassionate young girl. She is unashamed of her salvation and willingly spreads its message. Similarly, her father Undershaft is unashamed of his work in war and death. When Undershaft arrives in England, Barbara is unwillingly drawn into his ammunitions business affairs. She objects to this type of business, but through their sharing of ideas, her values and morals are thrown into question. She realizes that all religions glorify death and passivity and denial of the self. She begins to believe that Undershaft's "religion" and hers are no different. Based on this new belief, she chooses to leave the Salvation Army and to stay with Cusins working in her father's business. The second archetype of women is the socialite group. This is the group most criticized by their creators. These women have lives with no real meaning. They are devoted entirely to their outside activities, and cannot think apart from the rules of the society to which they belong. They will not hesitate to criticize the women who do not adhere to society's strict rules. Mrs. Turton in A Passage to India belongs to this Collier 3 archetype of women. She is a cruel, selfish woman because of absorption in herself and in the Anglo-Indian society. She even tries to convince Mrs. Moore and Adela of her ideas about Indians: "You're superior to them, don't forget that." [3] Lady Britomart is the socialite of Major Barbara. Her socialite manner begins in the home, and extends outward. She orders her children more than she mothers them. She is only concerned with family affairs if money is involved. She is enraged that Undershaft will not change his traditions of successorship to include her son Steven, and even more enraged at the immoral ideas that Undershaft shares with his children. The criticism brought upon these types of women by their author-creators seems to indicate the rules and standards of society mean nothing. It is the inside lives of men and women that make them heroines or heroes. These women have no initiative to change, and would be shunned from their societies if they were to do so. The idealistic archetype describes the women who pursue something

Free Essays on How Marriage Was Back In The 1800s

How Marriage was back in the 1800’s Kate Chopin’s The Storm and The Story of An Hour, recognizes that relationships can be missing something very important. The two stories tell about two different married couples who lack something in their lives. In the Story of an Hour, Mrs. Mallard is a lady afflicted with heart problems who feels completely sheltered inside (17). She is trapped physically by her husband and doesn’t know what to do. Mrs. Mallard feels unloved and very sad. But, there is nothing she can do but wait for better days to come. One day, her sister comes to relay a message to her that her husband had been killed in a train wreck (12). At first she expresses grief when she hears the news, but soon (unknown to her friends) she finds joy in it. So, the â€Å"sad message†(12), though sad to Richard, is in fact a happy message. She realizes that she is free now and can do as she wishes with no one to stand her way with many years to come. She becomes uncaring and selfish for she feels no sorrow at all for her husbands death (12). No one knows that she really feels this way and it will be a secret she would hold forever. Although, she loves him sometimes it is the greatest feeling and release of her life. But, her free life did not last long for the pain is too overwhelming when she sees that her husband is not dead and is standing before her. The doctors say that she â€Å"died of heart disease.† (18) In The Storm, Calixta is unable to fulfill society’s standards of virtue, despite her perceived purity by her lover Alcee. When Alcee professes, â€Å"If she was not and immaculate dove in those days, she was still inviolate.†(34), he is basically saying that just because a woman is chaste, does not mean she is not pure of heart. Calixta’s marriage stripped her of her chastity status. has two kinds of storms: a real one and a passionate storm. The real storm blows over just as the physical one do... Free Essays on How Marriage Was Back In The 1800's Free Essays on How Marriage Was Back In The 1800's How Marriage was back in the 1800’s Kate Chopin’s The Storm and The Story of An Hour, recognizes that relationships can be missing something very important. The two stories tell about two different married couples who lack something in their lives. In the Story of an Hour, Mrs. Mallard is a lady afflicted with heart problems who feels completely sheltered inside (17). She is trapped physically by her husband and doesn’t know what to do. Mrs. Mallard feels unloved and very sad. But, there is nothing she can do but wait for better days to come. One day, her sister comes to relay a message to her that her husband had been killed in a train wreck (12). At first she expresses grief when she hears the news, but soon (unknown to her friends) she finds joy in it. So, the â€Å"sad message†(12), though sad to Richard, is in fact a happy message. She realizes that she is free now and can do as she wishes with no one to stand her way with many years to come. She becomes uncaring and selfish for she feels no sorrow at all for her husbands death (12). No one knows that she really feels this way and it will be a secret she would hold forever. Although, she loves him sometimes it is the greatest feeling and release of her life. But, her free life did not last long for the pain is too overwhelming when she sees that her husband is not dead and is standing before her. The doctors say that she â€Å"died of heart disease.† (18) In The Storm, Calixta is unable to fulfill society’s standards of virtue, despite her perceived purity by her lover Alcee. When Alcee professes, â€Å"If she was not and immaculate dove in those days, she was still inviolate.†(34), he is basically saying that just because a woman is chaste, does not mean she is not pure of heart. Calixta’s marriage stripped her of her chastity status. has two kinds of storms: a real one and a passionate storm. The real storm blows over just as the physical one do...

MEMO Research Paper Example | Topics and Well Written Essays - 500 words

MEMO - Research Paper Example By using the mobile application automated services, the county government will be in a position to curb many of their challenges such as corruption as all payments will be done on a particular banking pool, leaving no chance of the money into person individual pockets as has been the previous occurrence. Despite the fact that this particular study is still in its preliminary stages, I have it in plan to organize the proposal by describing various sub-topics of research, which addresses various aspects pertaining to the automation of services at the county offices by the use of mobile application systems. †¢ The first aspect of the proposal would be the identification of the common problems at the county government offices, which include corruption, availability of ghost workers in payroll lists, and slow processing of services. †¢ The major challenges attributed to the problems stated above include reduced revenue collection as more money ends in the pockets of few individuals, funds needed to run the government services. Additionally, poor management and use of outdated systems equally contribute towards loss of cash from double payments made in particular workers’ accounts together with the payment of wages to non-existent workers. †¢ Finally, the mobile application system would work to provide solutions to the challenges mentioned above in such a way that payments would be done to a single pool ensuring that no cash lands in the handle of individual county government workers. In addition to such, automation of services would eliminate the instances of ghost workers emergence. For the successful application of the proposal, I have structured a number of methods that will be necessary for working the plan. The process involves developing a particular mobile application to be used by the clients in connecting with the government. Currently, the application is ready for use. What remains for the use of project is the development of the necessary

ASME code Essay Example | Topics and Well Written Essays - 500 words

ASME code - Essay Example Engineer B later requests Engineer B to visit B’s offices so that he may demonstrate to the company’s technical and management officials how the system works. Engineer A obliges and does the demonstration in detail. Engineer B asks Engineer A to prepare another proposal including the details of all costs involved. After some time, Engineer B’s company calls to inform Engineer A that the company will not need Engineer A’s company’s services since Engineer B’s company has achieved the capacity to make their own system. An analysis of the case presented above shows that Engineer B acted unethically in obtaining technical (and patented) information from Engineer A and using it without his consent. This act amounts to a breach of copyright/patent laws given that Engineer B uses the information they gain from A to his company’s advantage without seeking Engineer A’s consent. In the fundamental canons as stipulated in by the American S ociety of Mechanical Engineering (ASME), the engineer is required always to give respect to the intellectual property and proprietary information of other persons including professional bodies and charitable organizations (ASME 2006 No 6; ASME 2008 No 5). Engineer B’s company has proved through its actions not to be reputable given that it disrespects the property of Engineer A’s

Digital Signal Processing (DSP) and CDMA Advantages

Digital Signal Processing (DSP) and CDMA Advantages INTRODUCTION ANALOG AND DIGITAL SIGNALS The signal is initially generated is in the form of an analog electrical voltage or current, produced for example by a microphone or some other type of transducer. The output from the readout system of a CD (compact disc) player, the data is already in digital form. An analog signal must be converted into digital form before DSP techniques can be applied. An analog electrical voltage signal, for example, can be digitized using an electronic circuit called an analog-to-digital converter or ADC. This generates a digital output as a stream of binary numbers whose values represent the electrical voltage input to the device at each sampling instant. Digital signal processing (DSP)-digital representation of signals and the use of digital processors to analyze, modify, or extract information from signals. Many signals in DSP are derived from analogue signals which have been sampled at regular intervals and converted into digital form. The key advantages of DSP over analogue processing are Guaranteed accuracy (determined by the number of bits used) Perfect reproducibility No drift in performance due to temperature or age Takes advantage of advances in semiconductor technology Greater flexibility (can be reprogrammed without modifying hardware) Superior performance (linear phase response possible, and filtering algorithms can be made adaptive) Sometimes information may already be in digital form. There are however (still) some disadvantages Speed and cost (DSP design and hardware may be expensive, especially with high bandwidth signals) Finite word length problems (limited number of bits may cause degradation). Application areas of DSP are considerable: Image processing (pattern recognition, robotic vision, image enhancement, facsimile, satellite weather map, animation) Instrumentation and control (spectrum analysis, position and rate control, noise reduction, data compression) Speech and audio (speech recognition, speech synthesis, text to speech, digital audio, equalisation) Military (secure communication, radar processing, sonar processing, missile guidance) Telecommunications (echo cancellation, adaptive equalisation, spread spectrum, video conferencing, data communication) Biomedical (patient monitoring, scanners, EEG brain mappers, ECG analysis, X-ray storage and enhancement). INTRODUCTION TO CDMA Code Division Multiple Access (CDMA) is a radically new concept in wireless communications. It has gained widespread international acceptance by cellular radio system operators as an upgrade that will dramatically increase both their system capacity and the service quality. It has likewise been chosen for deployment by the majority of the winners of the United States Personal Communications System spectrum auctions. It may seem, however, mysterious for those who arent familiar with it. CDMA is a form of spread-spectrum, a family of digital communication techniques that have been used in military applications for many years. The core principle of spread spectrum is the use of noise-like carrier waves, and, as the name implies, bandwidths much wider than that required for simple point-to-point communication at the same data rate. Originally there were two motivations: either to resist enemy efforts to jam the communications (anti-jam, or AJ), or to hide the fact that communication was even taking place, sometimes called low probability of intercept (LPI). It has a history that goes back to the early days of World War II. The use of CDMA for civilian mobile radio applications is novel. It was proposed theoretically in the late 1940s, but the practical application in the civilian marketplace did not take place until 40 years later. Commercial applications became possible because of two evolutionary developments. One was the availability of very low cost, high density digital integrated circuits, which reduce the size, weight, and cost of the subscriber stations to an acceptably low level. The other was the realization that optimal multiple access communication requires that all user stations regulate their transmitter powers to the lowest that will achieve adequate signal quality. CDMA changes the nature of the subscriber station from a predominately analog device to a predominately digital device. Old-fashioned radio receivers separate stations or channels by filtering in the frequency domain. CDMA receivers do not eliminate analog processing entirely, but they separate communication channels by means of a pseudorandom modulation that is applied and removed in the digital domain, not on the basis of frequency. Multiple users occupy the same frequency band. This universal frequency reuse is not fortuitous. On the contrary, it is crucial to the very high spectral efficiency that is the hallmark of CDMA. Other discussions in these pages show why this is true. CDMA is altering the face of cellular and PCS communication by: Dramatically improving the telephone traffic capacity Dramatically improving the voice quality and eliminating the audible effects of multipath fading Reducing the incidence of dropped calls due to handoff failures Providing reliable transport mechanism for data communications, such as facsimile and internet traffic Reducing the number of sites needed to support any given amount of traffic Simplifying site selection Reducing deployment and operating costs because fewer cell sites are needed Reducing average transmitted power Reducing interference to other electronic devices Reducing potential health risks Commercially introduced in 1995, CDMA quickly became one of the worlds fastest growing wireless technologies. In 1999, the International Telecommunications Union selected CDMA as the industry standard for new third-generation (3G) wireless systems. Many leading wireless carriers are now building or upgrading to 3G CDMA networks in order to provide more capacity for voice traffic, along with high-speed data capabilities. DS_CDMA Multiple access systems based on DS CDMA have achieved increasing significance for mobile communications applications. A promising concept is based on DS_CDMA applying MRC at the receiver. MRC takes advantage of the channel diversity to combat the multipath fading. However the capacity of a DS_CDMA system is limited by both multi-user interference and inter symbol interference ISI in high data rate applications. OFDM is applied to combat the frequency selectivity of the channel using a simple one tap equalizer Further more OFDM prevents the ISI and inter carrier interference ICI by inserting a guard interval between adjacent OFDM symbols OFDM is typically used for audio TV and HDTV transmission over terrestrial channels and achieves high spectral efficiency. The CMDA Technology overview FDMA In Frequency Division Multiple Access, the frequency band is divided in slots. Each user gets one frequency slot assigned that is used at will. It could be compared to AM or FM broadcasting radio where each station has a frequency assigned. FDMA demands good filtering. TDMA In Time Division Multiple Access, the frequency band is not partitioned but users are allowed to use it only in predefined intervals of time, one at a time. Thus, TDMA demands synchronization among the users. CDMA CDMA, for Code Division Multiple Access, is different from its traditional ways in which it does not allocate frequency or time in user slots but gives the right to use both to all users simultaneously. To do this, it uses a technique known as Spread Spectrum . In effect, each user is assigned a code,which spreads its signal bandwidth in such a way that only the same code can recover it at the receiver end. This method has the property that the unwanted signals with different codes get spread even more by the process, making them like noise to the receiver . Spread Spectrum Spread Spectrum is a mean of transmission where the data occupies a larger bandwidth than necessary. Bandwidth spreading is accomplished before the transmission through the use of a code, which is independent of the transmitted data. The same code is used to demodulate the data at the receiving end. The following figure illustrate the spreading done on the data signal x(t) by the spreading signal c(t) resulting in the message signal to be transmitted, m(t). Originally for military use to avoid jamming (interference created on purpose to make a communication channel unusable), spread spectrum modulation is now used in personal communication systems for its superior performance in an interference dominated environment . Definition of Spread Spectrum: A transmission technique in which a pseudo-noise code, independent of the information data, is employed as a modulation waveform to â€Å"spread† the signal energy over a bandwidth much greater than the signal information bandwidth. At the receiver the signal is â€Å"despread† using a synchronized replica of the pseudo-noise code. Basic Principle of Spread Spectrum System: The Principal types of Spread Spectrum are Direct Sequence (DS), and Frequency Hopping (FH). An over view of these systems is hereby given: Pseudo shift of the phase pseudo shift of the frequency Coherent demodulation noncoherent Direct Sequence Spread Spectrum (DSSS) A pseudo-noise sequence pnt generated at the modulator, is used in conjunction with an M-ary PSK modulation to shift the phase of the PSK signal pseudo randomly, at the chipping rate Rc (=1/Tc) a rate that is integer multiple of the symbol rate Rs (=1/Ts). The transmitted bandwidth is determined by the chip rate and by the base band filtering. The implementation limits the maximum chip rate Rc (clock rate) and thus the maximum spreading. The PSK modulation scheme requires a coherent demodulation. PN code length that is much longer than a data symbol, so that a different chip pattern is associated with each symbol. Frequency Hopping Spread Spectrum A Pseudo-noise sequence pnt generated at the modulator is used in conjuction with an M-ary FSK modulation to shift the carrier frequency of the FSK signal pseudurandomly, at the hopping rate Rh. The transmitted signal occupies a number of frequencies in time, each for a period of time Th (= 1/Rh), referred as dwell time. FHSS divides the available bandwidth into N channels and hops between these channels according to the PN sequence. At each frequency hop time the PN generator feeds the frequency synthesizer a frequency word FW (a sequence of n chips) which dictates one of 2n frequency position fhl . Transmitter and receiver follows the same frequency hop pattern. The transmitted bandwidth is determined by the lowest and highest hop position by the bandwidth per hop position (à ¢Ã‹â€ Ã¢â‚¬  fch). For a given hop, instantaneous occupied bandwidth is the conventional M-FSK, which is typically much smaller than Wss. So the FHSS signal is a narrowband signal, all transmission power is concentrated on one channel. Averaged over many hops, the FH/M-FSK spectrum occupies the entire spread spectrum bandwidth. Because the bandwidth of an FHSS system only depends on the tuning range, it can be hopped over a much wider bandwidth than an DSSS system. Since the hops generally result in phase discontinuity (depending on the particular implementation) a noncoherent demodulation is done at receiver. With slow hopping there are multiple data symbol per hop and with fast hopping there are multiple hops per data symbol. 3.3 Basic principle of Direct Sequence Spread Spectrum For BPSK modulation the building blocks of a DSSS system are: Input: Binary data dt with symbol rate Rs = 1/Ts (=bitrate Rb for BPSK) Pseudo-noise code pnt with chip rate Rc = 1/Tc (an integer of Rs) Spreading: In the transmitter, the binary data dt (for BPSK, I and Q for QPSK) is ‘directly multiplied with the PN sequence pnt , which is independent of the binary data, to produce the transmitted baseband signal txb: txb = dt . pnt The effect of multiplication of dt with a PN sequence is to spread the baseband bandwidth Rs of dt to a baseband bandwidth of Rc. Despreading: The spread spectrum signal cannot be detected by a conventional narrowband receiver. In the receiver, the baseband signal rxb is multiplied with the PN sequence pnr . If pnr = pnt and synchronized to the PN sequence in the received data, than the recovered binary data is produced on dr. The effect of multiplication of the spread spectrum signal rxb with the PN sequence pnt used in the transmitter is to despread the bandwidth of rxb to Rs . If pnr ≠  pnt , than there is no dispreading action. The signal dr has a spread spectrum. A receiver not knowing the PN sequence of the transmitter can not reproduce the transmitted data. Performance in the presence of interference: To simplify the presence of interference, the spread spectrum system is considered for baseband BPSK communication (without filtering). The received signal rxb of the transmitted signal txb plus an additive inteferance i (noise, other users, jammer,†¦Ã¢â‚¬ ¦): rxb = t xb + i = dt . pnt + i To recover the original data dt the received signal rx0 is multiplied with a locally generated PN sequence pnr that is an exact replica of that used in the transmitter (that is pnr = pnt and synchronized) The multiplier output is therefore given by: dr = rxb . pnt = dt . pnt . pnt + i . pnt The data signal dt is multiplied twice by the PN sequence pnt , where as the unwanted inteferance i is multiplied only once. Due to the property of the PN sequence: pnt + pnt = +1 for all t The multiplier output becomes: dr = dt + i . pnt The data signal dr is reproduced at the multiplier output in the receiver, except for the inteferance represented by the additive term i . pnt . Multiplication of the inteferance by the locally generated PN sequence, means that the spreading code will affect the inteferance just as it did with the information bearing signal at the transmitter. Noise and inteferance, being uncorrelated with the PN sequence, becomes noise-like, increase in bandwidth and decrease in power density after the multiplier. After dispreading, the data component dt is narrow band (Rb) whereas the inteferance component is wideband (Rc). By applying the dr signal to a baseband (low-pass) filter with a band width just large enough to accommodate the recovery of the data signal, most of the inteferance component i is filtered out. The effect of inteferance is reduced by processing gain (Gp). Narrowband inteferance: The narrowband noise is spread by the multiplication with the PN sequence pnr of the receiver. The power density of the noise is reduced with respect to the despread data signal. Only 1/Gp of the original noise power is left in the information baseband (Rs). Spreading and dispreading enables a bandwidth trade for processing gain against narrow band interfering signals. Narrow band inteferance would disable conventional narrow band receivers. The essence behind the inteferance rejection capability of a spread spectrum system: the useful signal (data) gets multiplied twice by the PN sequence, but the inteferance signal get multiplied only once. Wideband interference: Multiplication of the received signal with the PN sequence of the receiver gets a selective despread of the data signal (smaller bandwidth, higher power density). The inteferance signal is uncorrelated with the PN sequence and is spread. Origin of wideband noise: Multiple Spread Spectrum user: multiple access mechanism. Gaussian Noise: There is no increase in SNR with spread spectrum: The large channel bandwidth (Rc instead of Rs) increase the received noise power with Gp: Ninfo = N0 . BWinfo à   Nss = N0 . BWss = Ninfo .Gp The spread spectrum signal has a lower power density than the directly transmitted signal. Code division multiple access (CDMA) is a methode of multiplexing (wireless) users distinct (orthogonal) codes. All users can transmit at the same time, and each is allocated the entire available frequency spectrum for transmission. CDMA is also known as Spread-Spectrum multiple access (SSMA). CDMA dose not require the bandwidth allocation of FDMA, nor the time synchronization of the individual users needed in TDMA. A CDMA user has full time and full bandwidth available, but the quality of the communication decreases with an increasing number of users (BER ). In CDMA each user: Has its own PN code Uses the same RF bandwidth Transmits simultaneously (asynchronous or synchronous) Correlation of the received baseband spread spectrum signal rxb with the PN sequence of user 1 only despreads the signal of user 1. The other user produces noise Nu for user 1. ACCESS SCHEMES For radio systems there are two resources, frequency and time. Division by frequency, so that each pair of communicators is allocated part of the spectrum for all of the time, results in Frequency Division Multiple Access (FDMA). Division by time, so that each pair of communicators is allocated all (or at least a large part) of the spectrum for part of the time results in Time Division Multiple Access (TDMA). In Code Division Multiple Access (CDMA), every communicator will be allocated the entire spectrum all of the time. CDMA uses codes to identify connections. MULTIPATH AND RAKE RECEIVERS One of the main advantages of CDMA systems is the capability of using signals that arrive in the receivers with different time delays. This phenomenon is called multipath. FDMA and TDMA, which are narrow band systems, cannot discriminate between the multipath arrivals, and resort to equalization to mitigate the negative effects of multipath. Due to its wide bandwidth and rake receivers, CDMA uses the multipath signals and combines them to make an even stronger signal at the receivers. CDMA subscriber units use rake receivers. This is essentially a set of several receivers. One of the receivers (fingers) constantly searches for different multipaths and feeds the information to the other three fingers. Each finger then demodulates the signal corresponding to a strong multipath. The results are then combined together to make the signal stronger. Difference between TDMA vs CDMA. TDMA is Time Division Multiple Access, while CDMA is Code Division Multiple Access. Both technologies achieve the same goal of better utilization of the radio spectrum by allowing multiple users to share the same physical channel, but by using different methods and that is why the three of the four words in each acronym are identical. Both allow more than one person to carry out a conversation on the same frequency without causing interference. The two technologies differ in the way in which users share the common resource. In TDMA the channel is chopped up into sequential time slices. The data of each user is put on the channel in a round-robin fashion. In reality, only one user actually uses the channel at any given point of time, but he uses it only for short bursts. He then gives up the channel for a short duration to allow the other users to have their turn. This is similar to how a computer with just one processor runs multiple applications simultaneously. CDMA on the other hand allows everyone to transmit at the same time. With conventional methods of modulation techniques it would hav been simply not possible. What makes CDMA to allow all users to transmit simultaneously is a special type of digital modulation called Spread Spectrum. In this modulation technique users stream of bits is taken and splattered them across a very wide channel in a pseudo-random fashion. The pseudo part is very important here as at the receiver end the randomization must be undone in order to collect the bits together in a coherent order. For example consider a room full of couples, and each couple trying to carry on one-on-one conversations. In TDMA each couple takes their turn for talking and they keep their turns short by speaking only one sentence at a time. As there is always more one person speaking in the room at any given point of time, no one has to worry about being heard over the background din. In CDMA assume each couple talks simultaneously, but they all use different languages. The background din doesnt cause any real problem as none of the listeners understand any language other than that of the individual to whom they are listening. Voice Encoding At this point many people confuse two distinctly different issues involved in the transmission of digital audio. The first is the WAY in which the stream of bits is delivered from one end to the other. This part of the air interface is what makes one technology different from another. The second is the compression algorithm used to squeeze the audio into as small a stream of bits as possible. This latter component is known at the Voice Coder, or Vocoder for short. Another term commonly used is CODEC, which is a similar word to modem. It combines the terms COder and DECoder. Although each technology has chosen their own unique CODECs, there is no rule saying that one transmission method needs to use a specific CODEC. People often lump a technologys transmission method with its CODEC as though they were single entities. Voice encoding schemes differ slightly in their approach to the problem. Because of this, certain types of human voice work better with some CODECs than they do with others. The point to remember is that all PCS CODECs are compromises of some sort. Since human voices have such a fantastic range of pitch and tonal depth, one cannot expect any single compromise to handle each one equally well. This inability to cope with all types of voice at the same level does lead some people to choose one technology over another. All of the PCS technologies try to minimize battery consumption during calls by keeping the transmission of unnecessary data to a minimum. The phone decides whether or not you are presently speaking, or if the sound it hears is just background noise. If the phone determines that there is no intelligent data to transmit it blanks the audio and it reduces the transmitter duty cycle (in the case of TDMA) or the number of transmitted bits (in the case of CDMA). When the audio is blanked your caller would suddenly find themselves listening to dead air, and this may cause them to think the call has dropped. To avoid this psychological problem many service providers insert what is known as Comfort Noise during the blanked periods. Comfort Noise is synthesized white noise that tries to mimic the volume and structure of the real background noise. This fake background noise assures the caller that the connection is alive and well. However, in newer CODECs such as EVRC (used exclusively on CDMA systems) the background noise is generally suppressed even while the user is talking. This piece of magic makes it sound as though the cell phone user is not in a noisy environment at all. Under these conditions, Comfort Noise is neither necessary, nor desirable. DS-CDMA-INTRODUCTION While multiple access interference (MAI) by other users has been recognized as the capacity-limiting factor in direct sequence code-division multiple-access (DS-CDMA)-based cellular communication systems, multiuser approaches have largely alleviated the problem when the noise process is additive Gaussian. With the availability of multiuser detectors, inaccurate or inappropriate noise modelling assumptions seem to have become the issue again. Whereas multiuser detection has much to offer in the mobile- to-base station uplink, it does not at present appear to be feasible for the downlink due to the complexity involved and the lack of resistance against adjacent cell interference. Moreover, the few multiuser proposals for the downlink require the knowledge of all spreading codes, which is not possible in the tactical military environment, for instance. Enhanced single-user receivers equipped with adaptive filter banks deliver promising performance with reasonable complexity, especially in slowly varying channels. Thus, the performance of single-user detectors is still of interest, particularly in the presence of non-Gaussian noise. In both urban outdoor and indoor mobile radio environments, electromagnetic interference generated by man-made sources such as factories or power lines causes the noise to be of non-Gaussian nature. Large noise magnitudes are deemed very improbable by linear receivers, and consequently performance deterioration is experienced. It is therefore desirable to build systems that can maintain respectable functionality under a broad class of noise distributions, rather than strictly optimizing for the unrealistic Gaussian assumption. Such is the goal of robust detection and estimation theory, which aims to design systems that are suboptimal under nominal channel conditions (e.g., Gaussian channel) and yet do not face catastrophy when the noise distribution is not nominal (e.g., unlike linear schemes). Note that suboptimality here refers to very good performance that is slightly worse than that of the nominal-optimal detector/estimator. The direct sequence code division multiple access (DS-CDMA) technique has been favourably considered for application in digital mobile cellular networks due to its potential to provide higher system capacity over conventional multiple access techniques. Unlike FDMA and TDMA capacities which are mostly limited by the bandwidth, the capacity of a CDMA system is mainly restricted by its interference level. Any reduction in interference produces a direct and linear increase in system capacity. Multiple access interference (MAI) caused by non-zero cross-correlation between different spreading sequences is the major type of interference limiting the CDMA system capacity. Much work has been done to characterize MAI, and to analyze and evaluate the CDMA system performance in the presence of MAI. Since the cross-correlation properties of most sets of spreading codes are either too complex to analyze or very difficult to compute when different transmissions are not synchronized, a random seque nce model. In the case of moderate to large processing gains, Gaussian distribution with variable variance is a good approximation for the MAI distribution. One of the approaches to reduce MAI is to employ orthogonal spreading sequences, and try to synchronize the transmissions at the chip level (quasi-synchronization). However, this is generally difficult to achieve in multipoint-to-point systems, such as the reverse link (mobile-to-base) of a cellular system, due to a lack of synchronization of the various mobile terminals, and the variable transmission delays. In this paper, a multi-carrier DS-CDMA (MCDS-CDMA) scheme is employed to facilitate the synchronization process, and thus reduce MAI. SYSTEM MODEL A model of the MS-DS-CDMA system for the kth user of a CDMA system is shown in the figure 1. TRANMSITTER MODEL At the transmitter the user‘s data stream dk(t) is divided into M interleaved sub streams and spread by a spreading sequence ck(t) to a fraction 1/M of the entire transmission bandwidth W. The resultant chip sequences are then used to modulate M carrier. The carrier frequencies ωm,m=1,2,M are equally spaced by the chip rate so that they are mutually orthogonal over one channel symbol interval T. Let R be the information rate and Rc be the carrier control code rate then the channel symbol interval is BER PERFORMANCE: MC-DS-CDMA system performance measured by bit error rate through analysis and simulation. Analysis: The BER is analysed based on the following: Ortoganal spreading sequences with rectangular pulse shape are applied. ÃŽ ¶k,k=1†¦K are independent of random variables distributd in (-ÃŽ ¶D,ÃŽ ¶D) WHERE ÃŽ ¶D=ÃŽ µD+Ï‚D.Given W and ÃŽ ¶D,M is chosen so that ÃŽ ¶D It is assumed that the fading parameters of the desired user . It is perfectly estimated so that the coherent detection and optimum soft decision decoding could be carried out at the receiver to make the problem analytically tractable. The fading amplitudes as independent Rayleigh random variables with equal second moments. The model is MATLAB INTRODUCTION: Matlab is a commercial Matrix Laboratory package which operates as an interactive programming environment. It is a mainstay of the Mathematics Department software lineup and is also available for PCs and Macintoshes and may be found on the CIRCA VAXes. Matlab is well adapted to numerical experiments since the underlying algorithms for Matlabs builtin functions and supplied m-files are based on the standard libraries LINPACK and EISPACK. Matlab program and script files always have filenames ending with .m; the programming language is exceptionally straightforward since almost every data object is assumed to be an array. Graphical output is available to supplement numerical results. IMREAD Read image from graphics file. A = IMREAD(FILENAME,FMT) reads a grayscale or color image from the file specified by the string FILENAME. If the file is not in the current directory, or in a directory on the MATLAB path, specify the full pathname. The text string FMT specifies the format of the file by its standard file extension. For example, specify gif Digital Signal Processing (DSP) and CDMA Advantages Digital Signal Processing (DSP) and CDMA Advantages INTRODUCTION ANALOG AND DIGITAL SIGNALS The signal is initially generated is in the form of an analog electrical voltage or current, produced for example by a microphone or some other type of transducer. The output from the readout system of a CD (compact disc) player, the data is already in digital form. An analog signal must be converted into digital form before DSP techniques can be applied. An analog electrical voltage signal, for example, can be digitized using an electronic circuit called an analog-to-digital converter or ADC. This generates a digital output as a stream of binary numbers whose values represent the electrical voltage input to the device at each sampling instant. Digital signal processing (DSP)-digital representation of signals and the use of digital processors to analyze, modify, or extract information from signals. Many signals in DSP are derived from analogue signals which have been sampled at regular intervals and converted into digital form. The key advantages of DSP over analogue processing are Guaranteed accuracy (determined by the number of bits used) Perfect reproducibility No drift in performance due to temperature or age Takes advantage of advances in semiconductor technology Greater flexibility (can be reprogrammed without modifying hardware) Superior performance (linear phase response possible, and filtering algorithms can be made adaptive) Sometimes information may already be in digital form. There are however (still) some disadvantages Speed and cost (DSP design and hardware may be expensive, especially with high bandwidth signals) Finite word length problems (limited number of bits may cause degradation). Application areas of DSP are considerable: Image processing (pattern recognition, robotic vision, image enhancement, facsimile, satellite weather map, animation) Instrumentation and control (spectrum analysis, position and rate control, noise reduction, data compression) Speech and audio (speech recognition, speech synthesis, text to speech, digital audio, equalisation) Military (secure communication, radar processing, sonar processing, missile guidance) Telecommunications (echo cancellation, adaptive equalisation, spread spectrum, video conferencing, data communication) Biomedical (patient monitoring, scanners, EEG brain mappers, ECG analysis, X-ray storage and enhancement). INTRODUCTION TO CDMA Code Division Multiple Access (CDMA) is a radically new concept in wireless communications. It has gained widespread international acceptance by cellular radio system operators as an upgrade that will dramatically increase both their system capacity and the service quality. It has likewise been chosen for deployment by the majority of the winners of the United States Personal Communications System spectrum auctions. It may seem, however, mysterious for those who arent familiar with it. CDMA is a form of spread-spectrum, a family of digital communication techniques that have been used in military applications for many years. The core principle of spread spectrum is the use of noise-like carrier waves, and, as the name implies, bandwidths much wider than that required for simple point-to-point communication at the same data rate. Originally there were two motivations: either to resist enemy efforts to jam the communications (anti-jam, or AJ), or to hide the fact that communication was even taking place, sometimes called low probability of intercept (LPI). It has a history that goes back to the early days of World War II. The use of CDMA for civilian mobile radio applications is novel. It was proposed theoretically in the late 1940s, but the practical application in the civilian marketplace did not take place until 40 years later. Commercial applications became possible because of two evolutionary developments. One was the availability of very low cost, high density digital integrated circuits, which reduce the size, weight, and cost of the subscriber stations to an acceptably low level. The other was the realization that optimal multiple access communication requires that all user stations regulate their transmitter powers to the lowest that will achieve adequate signal quality. CDMA changes the nature of the subscriber station from a predominately analog device to a predominately digital device. Old-fashioned radio receivers separate stations or channels by filtering in the frequency domain. CDMA receivers do not eliminate analog processing entirely, but they separate communication channels by means of a pseudorandom modulation that is applied and removed in the digital domain, not on the basis of frequency. Multiple users occupy the same frequency band. This universal frequency reuse is not fortuitous. On the contrary, it is crucial to the very high spectral efficiency that is the hallmark of CDMA. Other discussions in these pages show why this is true. CDMA is altering the face of cellular and PCS communication by: Dramatically improving the telephone traffic capacity Dramatically improving the voice quality and eliminating the audible effects of multipath fading Reducing the incidence of dropped calls due to handoff failures Providing reliable transport mechanism for data communications, such as facsimile and internet traffic Reducing the number of sites needed to support any given amount of traffic Simplifying site selection Reducing deployment and operating costs because fewer cell sites are needed Reducing average transmitted power Reducing interference to other electronic devices Reducing potential health risks Commercially introduced in 1995, CDMA quickly became one of the worlds fastest growing wireless technologies. In 1999, the International Telecommunications Union selected CDMA as the industry standard for new third-generation (3G) wireless systems. Many leading wireless carriers are now building or upgrading to 3G CDMA networks in order to provide more capacity for voice traffic, along with high-speed data capabilities. DS_CDMA Multiple access systems based on DS CDMA have achieved increasing significance for mobile communications applications. A promising concept is based on DS_CDMA applying MRC at the receiver. MRC takes advantage of the channel diversity to combat the multipath fading. However the capacity of a DS_CDMA system is limited by both multi-user interference and inter symbol interference ISI in high data rate applications. OFDM is applied to combat the frequency selectivity of the channel using a simple one tap equalizer Further more OFDM prevents the ISI and inter carrier interference ICI by inserting a guard interval between adjacent OFDM symbols OFDM is typically used for audio TV and HDTV transmission over terrestrial channels and achieves high spectral efficiency. The CMDA Technology overview FDMA In Frequency Division Multiple Access, the frequency band is divided in slots. Each user gets one frequency slot assigned that is used at will. It could be compared to AM or FM broadcasting radio where each station has a frequency assigned. FDMA demands good filtering. TDMA In Time Division Multiple Access, the frequency band is not partitioned but users are allowed to use it only in predefined intervals of time, one at a time. Thus, TDMA demands synchronization among the users. CDMA CDMA, for Code Division Multiple Access, is different from its traditional ways in which it does not allocate frequency or time in user slots but gives the right to use both to all users simultaneously. To do this, it uses a technique known as Spread Spectrum . In effect, each user is assigned a code,which spreads its signal bandwidth in such a way that only the same code can recover it at the receiver end. This method has the property that the unwanted signals with different codes get spread even more by the process, making them like noise to the receiver . Spread Spectrum Spread Spectrum is a mean of transmission where the data occupies a larger bandwidth than necessary. Bandwidth spreading is accomplished before the transmission through the use of a code, which is independent of the transmitted data. The same code is used to demodulate the data at the receiving end. The following figure illustrate the spreading done on the data signal x(t) by the spreading signal c(t) resulting in the message signal to be transmitted, m(t). Originally for military use to avoid jamming (interference created on purpose to make a communication channel unusable), spread spectrum modulation is now used in personal communication systems for its superior performance in an interference dominated environment . Definition of Spread Spectrum: A transmission technique in which a pseudo-noise code, independent of the information data, is employed as a modulation waveform to â€Å"spread† the signal energy over a bandwidth much greater than the signal information bandwidth. At the receiver the signal is â€Å"despread† using a synchronized replica of the pseudo-noise code. Basic Principle of Spread Spectrum System: The Principal types of Spread Spectrum are Direct Sequence (DS), and Frequency Hopping (FH). An over view of these systems is hereby given: Pseudo shift of the phase pseudo shift of the frequency Coherent demodulation noncoherent Direct Sequence Spread Spectrum (DSSS) A pseudo-noise sequence pnt generated at the modulator, is used in conjunction with an M-ary PSK modulation to shift the phase of the PSK signal pseudo randomly, at the chipping rate Rc (=1/Tc) a rate that is integer multiple of the symbol rate Rs (=1/Ts). The transmitted bandwidth is determined by the chip rate and by the base band filtering. The implementation limits the maximum chip rate Rc (clock rate) and thus the maximum spreading. The PSK modulation scheme requires a coherent demodulation. PN code length that is much longer than a data symbol, so that a different chip pattern is associated with each symbol. Frequency Hopping Spread Spectrum A Pseudo-noise sequence pnt generated at the modulator is used in conjuction with an M-ary FSK modulation to shift the carrier frequency of the FSK signal pseudurandomly, at the hopping rate Rh. The transmitted signal occupies a number of frequencies in time, each for a period of time Th (= 1/Rh), referred as dwell time. FHSS divides the available bandwidth into N channels and hops between these channels according to the PN sequence. At each frequency hop time the PN generator feeds the frequency synthesizer a frequency word FW (a sequence of n chips) which dictates one of 2n frequency position fhl . Transmitter and receiver follows the same frequency hop pattern. The transmitted bandwidth is determined by the lowest and highest hop position by the bandwidth per hop position (à ¢Ã‹â€ Ã¢â‚¬  fch). For a given hop, instantaneous occupied bandwidth is the conventional M-FSK, which is typically much smaller than Wss. So the FHSS signal is a narrowband signal, all transmission power is concentrated on one channel. Averaged over many hops, the FH/M-FSK spectrum occupies the entire spread spectrum bandwidth. Because the bandwidth of an FHSS system only depends on the tuning range, it can be hopped over a much wider bandwidth than an DSSS system. Since the hops generally result in phase discontinuity (depending on the particular implementation) a noncoherent demodulation is done at receiver. With slow hopping there are multiple data symbol per hop and with fast hopping there are multiple hops per data symbol. 3.3 Basic principle of Direct Sequence Spread Spectrum For BPSK modulation the building blocks of a DSSS system are: Input: Binary data dt with symbol rate Rs = 1/Ts (=bitrate Rb for BPSK) Pseudo-noise code pnt with chip rate Rc = 1/Tc (an integer of Rs) Spreading: In the transmitter, the binary data dt (for BPSK, I and Q for QPSK) is ‘directly multiplied with the PN sequence pnt , which is independent of the binary data, to produce the transmitted baseband signal txb: txb = dt . pnt The effect of multiplication of dt with a PN sequence is to spread the baseband bandwidth Rs of dt to a baseband bandwidth of Rc. Despreading: The spread spectrum signal cannot be detected by a conventional narrowband receiver. In the receiver, the baseband signal rxb is multiplied with the PN sequence pnr . If pnr = pnt and synchronized to the PN sequence in the received data, than the recovered binary data is produced on dr. The effect of multiplication of the spread spectrum signal rxb with the PN sequence pnt used in the transmitter is to despread the bandwidth of rxb to Rs . If pnr ≠  pnt , than there is no dispreading action. The signal dr has a spread spectrum. A receiver not knowing the PN sequence of the transmitter can not reproduce the transmitted data. Performance in the presence of interference: To simplify the presence of interference, the spread spectrum system is considered for baseband BPSK communication (without filtering). The received signal rxb of the transmitted signal txb plus an additive inteferance i (noise, other users, jammer,†¦Ã¢â‚¬ ¦): rxb = t xb + i = dt . pnt + i To recover the original data dt the received signal rx0 is multiplied with a locally generated PN sequence pnr that is an exact replica of that used in the transmitter (that is pnr = pnt and synchronized) The multiplier output is therefore given by: dr = rxb . pnt = dt . pnt . pnt + i . pnt The data signal dt is multiplied twice by the PN sequence pnt , where as the unwanted inteferance i is multiplied only once. Due to the property of the PN sequence: pnt + pnt = +1 for all t The multiplier output becomes: dr = dt + i . pnt The data signal dr is reproduced at the multiplier output in the receiver, except for the inteferance represented by the additive term i . pnt . Multiplication of the inteferance by the locally generated PN sequence, means that the spreading code will affect the inteferance just as it did with the information bearing signal at the transmitter. Noise and inteferance, being uncorrelated with the PN sequence, becomes noise-like, increase in bandwidth and decrease in power density after the multiplier. After dispreading, the data component dt is narrow band (Rb) whereas the inteferance component is wideband (Rc). By applying the dr signal to a baseband (low-pass) filter with a band width just large enough to accommodate the recovery of the data signal, most of the inteferance component i is filtered out. The effect of inteferance is reduced by processing gain (Gp). Narrowband inteferance: The narrowband noise is spread by the multiplication with the PN sequence pnr of the receiver. The power density of the noise is reduced with respect to the despread data signal. Only 1/Gp of the original noise power is left in the information baseband (Rs). Spreading and dispreading enables a bandwidth trade for processing gain against narrow band interfering signals. Narrow band inteferance would disable conventional narrow band receivers. The essence behind the inteferance rejection capability of a spread spectrum system: the useful signal (data) gets multiplied twice by the PN sequence, but the inteferance signal get multiplied only once. Wideband interference: Multiplication of the received signal with the PN sequence of the receiver gets a selective despread of the data signal (smaller bandwidth, higher power density). The inteferance signal is uncorrelated with the PN sequence and is spread. Origin of wideband noise: Multiple Spread Spectrum user: multiple access mechanism. Gaussian Noise: There is no increase in SNR with spread spectrum: The large channel bandwidth (Rc instead of Rs) increase the received noise power with Gp: Ninfo = N0 . BWinfo à   Nss = N0 . BWss = Ninfo .Gp The spread spectrum signal has a lower power density than the directly transmitted signal. Code division multiple access (CDMA) is a methode of multiplexing (wireless) users distinct (orthogonal) codes. All users can transmit at the same time, and each is allocated the entire available frequency spectrum for transmission. CDMA is also known as Spread-Spectrum multiple access (SSMA). CDMA dose not require the bandwidth allocation of FDMA, nor the time synchronization of the individual users needed in TDMA. A CDMA user has full time and full bandwidth available, but the quality of the communication decreases with an increasing number of users (BER ). In CDMA each user: Has its own PN code Uses the same RF bandwidth Transmits simultaneously (asynchronous or synchronous) Correlation of the received baseband spread spectrum signal rxb with the PN sequence of user 1 only despreads the signal of user 1. The other user produces noise Nu for user 1. ACCESS SCHEMES For radio systems there are two resources, frequency and time. Division by frequency, so that each pair of communicators is allocated part of the spectrum for all of the time, results in Frequency Division Multiple Access (FDMA). Division by time, so that each pair of communicators is allocated all (or at least a large part) of the spectrum for part of the time results in Time Division Multiple Access (TDMA). In Code Division Multiple Access (CDMA), every communicator will be allocated the entire spectrum all of the time. CDMA uses codes to identify connections. MULTIPATH AND RAKE RECEIVERS One of the main advantages of CDMA systems is the capability of using signals that arrive in the receivers with different time delays. This phenomenon is called multipath. FDMA and TDMA, which are narrow band systems, cannot discriminate between the multipath arrivals, and resort to equalization to mitigate the negative effects of multipath. Due to its wide bandwidth and rake receivers, CDMA uses the multipath signals and combines them to make an even stronger signal at the receivers. CDMA subscriber units use rake receivers. This is essentially a set of several receivers. One of the receivers (fingers) constantly searches for different multipaths and feeds the information to the other three fingers. Each finger then demodulates the signal corresponding to a strong multipath. The results are then combined together to make the signal stronger. Difference between TDMA vs CDMA. TDMA is Time Division Multiple Access, while CDMA is Code Division Multiple Access. Both technologies achieve the same goal of better utilization of the radio spectrum by allowing multiple users to share the same physical channel, but by using different methods and that is why the three of the four words in each acronym are identical. Both allow more than one person to carry out a conversation on the same frequency without causing interference. The two technologies differ in the way in which users share the common resource. In TDMA the channel is chopped up into sequential time slices. The data of each user is put on the channel in a round-robin fashion. In reality, only one user actually uses the channel at any given point of time, but he uses it only for short bursts. He then gives up the channel for a short duration to allow the other users to have their turn. This is similar to how a computer with just one processor runs multiple applications simultaneously. CDMA on the other hand allows everyone to transmit at the same time. With conventional methods of modulation techniques it would hav been simply not possible. What makes CDMA to allow all users to transmit simultaneously is a special type of digital modulation called Spread Spectrum. In this modulation technique users stream of bits is taken and splattered them across a very wide channel in a pseudo-random fashion. The pseudo part is very important here as at the receiver end the randomization must be undone in order to collect the bits together in a coherent order. For example consider a room full of couples, and each couple trying to carry on one-on-one conversations. In TDMA each couple takes their turn for talking and they keep their turns short by speaking only one sentence at a time. As there is always more one person speaking in the room at any given point of time, no one has to worry about being heard over the background din. In CDMA assume each couple talks simultaneously, but they all use different languages. The background din doesnt cause any real problem as none of the listeners understand any language other than that of the individual to whom they are listening. Voice Encoding At this point many people confuse two distinctly different issues involved in the transmission of digital audio. The first is the WAY in which the stream of bits is delivered from one end to the other. This part of the air interface is what makes one technology different from another. The second is the compression algorithm used to squeeze the audio into as small a stream of bits as possible. This latter component is known at the Voice Coder, or Vocoder for short. Another term commonly used is CODEC, which is a similar word to modem. It combines the terms COder and DECoder. Although each technology has chosen their own unique CODECs, there is no rule saying that one transmission method needs to use a specific CODEC. People often lump a technologys transmission method with its CODEC as though they were single entities. Voice encoding schemes differ slightly in their approach to the problem. Because of this, certain types of human voice work better with some CODECs than they do with others. The point to remember is that all PCS CODECs are compromises of some sort. Since human voices have such a fantastic range of pitch and tonal depth, one cannot expect any single compromise to handle each one equally well. This inability to cope with all types of voice at the same level does lead some people to choose one technology over another. All of the PCS technologies try to minimize battery consumption during calls by keeping the transmission of unnecessary data to a minimum. The phone decides whether or not you are presently speaking, or if the sound it hears is just background noise. If the phone determines that there is no intelligent data to transmit it blanks the audio and it reduces the transmitter duty cycle (in the case of TDMA) or the number of transmitted bits (in the case of CDMA). When the audio is blanked your caller would suddenly find themselves listening to dead air, and this may cause them to think the call has dropped. To avoid this psychological problem many service providers insert what is known as Comfort Noise during the blanked periods. Comfort Noise is synthesized white noise that tries to mimic the volume and structure of the real background noise. This fake background noise assures the caller that the connection is alive and well. However, in newer CODECs such as EVRC (used exclusively on CDMA systems) the background noise is generally suppressed even while the user is talking. This piece of magic makes it sound as though the cell phone user is not in a noisy environment at all. Under these conditions, Comfort Noise is neither necessary, nor desirable. DS-CDMA-INTRODUCTION While multiple access interference (MAI) by other users has been recognized as the capacity-limiting factor in direct sequence code-division multiple-access (DS-CDMA)-based cellular communication systems, multiuser approaches have largely alleviated the problem when the noise process is additive Gaussian. With the availability of multiuser detectors, inaccurate or inappropriate noise modelling assumptions seem to have become the issue again. Whereas multiuser detection has much to offer in the mobile- to-base station uplink, it does not at present appear to be feasible for the downlink due to the complexity involved and the lack of resistance against adjacent cell interference. Moreover, the few multiuser proposals for the downlink require the knowledge of all spreading codes, which is not possible in the tactical military environment, for instance. Enhanced single-user receivers equipped with adaptive filter banks deliver promising performance with reasonable complexity, especially in slowly varying channels. Thus, the performance of single-user detectors is still of interest, particularly in the presence of non-Gaussian noise. In both urban outdoor and indoor mobile radio environments, electromagnetic interference generated by man-made sources such as factories or power lines causes the noise to be of non-Gaussian nature. Large noise magnitudes are deemed very improbable by linear receivers, and consequently performance deterioration is experienced. It is therefore desirable to build systems that can maintain respectable functionality under a broad class of noise distributions, rather than strictly optimizing for the unrealistic Gaussian assumption. Such is the goal of robust detection and estimation theory, which aims to design systems that are suboptimal under nominal channel conditions (e.g., Gaussian channel) and yet do not face catastrophy when the noise distribution is not nominal (e.g., unlike linear schemes). Note that suboptimality here refers to very good performance that is slightly worse than that of the nominal-optimal detector/estimator. The direct sequence code division multiple access (DS-CDMA) technique has been favourably considered for application in digital mobile cellular networks due to its potential to provide higher system capacity over conventional multiple access techniques. Unlike FDMA and TDMA capacities which are mostly limited by the bandwidth, the capacity of a CDMA system is mainly restricted by its interference level. Any reduction in interference produces a direct and linear increase in system capacity. Multiple access interference (MAI) caused by non-zero cross-correlation between different spreading sequences is the major type of interference limiting the CDMA system capacity. Much work has been done to characterize MAI, and to analyze and evaluate the CDMA system performance in the presence of MAI. Since the cross-correlation properties of most sets of spreading codes are either too complex to analyze or very difficult to compute when different transmissions are not synchronized, a random seque nce model. In the case of moderate to large processing gains, Gaussian distribution with variable variance is a good approximation for the MAI distribution. One of the approaches to reduce MAI is to employ orthogonal spreading sequences, and try to synchronize the transmissions at the chip level (quasi-synchronization). However, this is generally difficult to achieve in multipoint-to-point systems, such as the reverse link (mobile-to-base) of a cellular system, due to a lack of synchronization of the various mobile terminals, and the variable transmission delays. In this paper, a multi-carrier DS-CDMA (MCDS-CDMA) scheme is employed to facilitate the synchronization process, and thus reduce MAI. SYSTEM MODEL A model of the MS-DS-CDMA system for the kth user of a CDMA system is shown in the figure 1. TRANMSITTER MODEL At the transmitter the user‘s data stream dk(t) is divided into M interleaved sub streams and spread by a spreading sequence ck(t) to a fraction 1/M of the entire transmission bandwidth W. The resultant chip sequences are then used to modulate M carrier. The carrier frequencies ωm,m=1,2,M are equally spaced by the chip rate so that they are mutually orthogonal over one channel symbol interval T. Let R be the information rate and Rc be the carrier control code rate then the channel symbol interval is BER PERFORMANCE: MC-DS-CDMA system performance measured by bit error rate through analysis and simulation. Analysis: The BER is analysed based on the following: Ortoganal spreading sequences with rectangular pulse shape are applied. ÃŽ ¶k,k=1†¦K are independent of random variables distributd in (-ÃŽ ¶D,ÃŽ ¶D) WHERE ÃŽ ¶D=ÃŽ µD+Ï‚D.Given W and ÃŽ ¶D,M is chosen so that ÃŽ ¶D It is assumed that the fading parameters of the desired user . It is perfectly estimated so that the coherent detection and optimum soft decision decoding could be carried out at the receiver to make the problem analytically tractable. The fading amplitudes as independent Rayleigh random variables with equal second moments. The model is MATLAB INTRODUCTION: Matlab is a commercial Matrix Laboratory package which operates as an interactive programming environment. It is a mainstay of the Mathematics Department software lineup and is also available for PCs and Macintoshes and may be found on the CIRCA VAXes. Matlab is well adapted to numerical experiments since the underlying algorithms for Matlabs builtin functions and supplied m-files are based on the standard libraries LINPACK and EISPACK. Matlab program and script files always have filenames ending with .m; the programming language is exceptionally straightforward since almost every data object is assumed to be an array. Graphical output is available to supplement numerical results. IMREAD Read image from graphics file. A = IMREAD(FILENAME,FMT) reads a grayscale or color image from the file specified by the string FILENAME. If the file is not in the current directory, or in a directory on the MATLAB path, specify the full pathname. The text string FMT specifies the format of the file by its standard file extension. For example, specify gif