Becoming a Computer Engineer Essay Example For Students

Turning into a Computer Engineer Essay For as long as six years, I have been doing a great deal of soul looking about what I will do with my life. I have gone from being a drug store expert, a detailer for a vehicle sales center, and a military police officer in the United States Air-Force (USAF). I was bouncing starting with one field then onto the next, and I didn't have an ability to know east from west on what I would have been throughout everyday life. At that point one night, while I was riding the web with my MacBook Pro, I tapped the track-cushion to look for â€Å"bum fights† on YouTube, and a switch clicked in my mind. I had a revelation. I was intended to be a PC architect, and I imagined myself in an IBM business wearing a sterile garment over a decent Italian suit chattering about a specific sort of advancement I am chipping away at for PCs, and how I am â€Å"building a more brilliant planet†. This incited me to explore the way to obtaining a bachelor’s certificate in PC building, general depiction and employment standpoint of the occupation, and a down to earth ability I have to learn if there should arise an occurrence of a prophetically catastrophic occasion. I discovered that it would be a long and exhausting way to accomplish a bachelor’s qualification in PC designing. So as to begin my profession as a PC equipment engineer, I would need to get a bachelor’s qualification in a PC designing project perceived by the ABET (earlier the Accreditation Board for Engineering and Technology) (United States). To obtain my bachelor’s qualification, I am as of now going to Southwestern College (SWC), and I am intending to move to SDSU or UCSD on the grounds that the two colleges offer building programs certify by the ABET. To get ready for my major, SWC expects me to complete the entirety of my general training prerequisites. This comprises of a broad rundown of math, material science, and two or three designing courses which may take me a few years to achieve so as to move to one of my favored colleges. At that point in the wake of moving, it might take me another a few years to get all the credits I need so as to graduate. It will be an extensive and burdensome excursion to achieve my objective, yet I am propelled by my family’s help and support. Likewise, I feel honored and advantaged that I won't be among the level of undergrads graduating paying off debtors from understudy advances; my GI bill will cover a segment of my educational cost, and my mom has elected to cover the rest. An average typical day for a PC equipment architect would comprise of the social occasion of PC chip and equipment necessities, and furthermore the programming of UIs for the fabricated equipment (Dela Cruz). Furthermore, the development of the equipment requires quality confirmation testing to fulfill the necessities of the client’s demand (Dela Cruz). The workplace of a PC equipment architect may incorporate a great deal of specialized and cutting edge gear, including machines that can create PC chips and equipment (Dela Cruz). Gatherings are typical and useful, particularly for conversations about your team’s current assignment (Dela Cruz). With the entirety of the specialized and cutting edge hardware at the work site, one would figure it would be an exceptionally distressing condition. Rather Ryan Dela Cruz states, â€Å"It has a low-stress condition, however worries at the work site can shift. One of the essential anxieties is the fruition of a task that’s near a cutoff time particularly if there are startling mistakes during the last period of an undertaking. † Dela Cruz additionally included that the kinship and the strong cooperation between engineers keeps the feelings of anxiety low in the workplace. As per my companion, Ryan Dela Cruz, a PC equipment engineer for IBM, work hours can differ from forty to sixty hours out of every week relying upon the current venture. Normally, PC equipment engineers are all day laborers that can procure a normal pay of one hundred thousand dollars per year (United States). Assault of Lock ; The Eve of St Agnes EssayIf one has questions about these expressions, every one of the one needs to do is perused or watch quantities of joblessness, vagrancy, expanding Visa obligation, and our descending fall of humankind that is sinking as decades creep up on all of us. As I led my exploration I discovered that it may take me five to six years of school to achieve a bachelor’s certificate in PC building. I am likewise enthused to turn into a PC engineer in view of the cutting edge and effortless workplace. Despite the fact that the business rate for the PC designing field is lethargic, it will be a snap to catch a passage level position due to the trusted status I procured from the USAF. Additionally, I got some answers concerning a functional expertise or my â€Å"emergency chute†, for example, urban homesteading that training maintainable living abilities. To have a back up plan and not need it is better than requiring a back-up plan and not having it. Ideally, with confidence, backbone, assurance, and God’s will, my arrangement will take full trip to boundless potential in proficient, just as self-improvement and a wealth of intelligence, clearness, and core interest. Catalog: Auza, Melvin. Individual meeting. 21 Nov. 2012. California. Business Development Department. PC Hardware Engineers in California. N.p., 2010. Web. 27 Nov. 2012. Dela Cruz, Ryan. Individual meeting. 28 Nov. 2012. US. Branch of Labor. Department of Labor Statistics. PC Hardware Specialists. Word related Outlook Handbook, 29 Mar. 2012. Web. 20 Nov. 2012. â€Å"Urban Homesteading.† Wikipedia. Wikimedia Foundation, 23 Oct. 2012. Web. 26 Nov. 2012.

Comparison of Wedding of India and China Free Essays

The methodology of these administrative work is to know and think about the two country’s convention with regards to wedding. Looking at wedding, we as a whole realize that it is the significant perspective when two individuals need to enter the life of having a family. As indicated by Webster, wedding is the service of marriage with its going with merry. We will compose a custom exposition test on Examination of Wedding of India and China or then again any comparative subject just for you Request Now Furthermore, as I go on with these desk work, we will all realize the various customs in wedding of the two nations and its accounts. To officially begin this subject, we should initially know the two country’s wedding history. In India, history of Indian Wedding says that early social orders for social just as political reasons needed to have secure methods for the propagation of the species and an establishment to deal with the allowing of property rights and marriage was the foundation for satisfying that need. History of Indian Wedding says that early social orders for social just as political reasons needed to have secure methods for the propagation of the species and an organization to deal with the conceding of property rights and marriage was the foundation for satisfying that need. In Indian culture organized relationships have a history since fourth century. The way of life of orchestrated relationships has still endure modernization and industrialization in India. Old occasions, the relationships occurred while the couple was extremely youthful. Truth be told, the kid's folks looked for a coordinating collusion for him in his preadolescent age and afterward moved toward the young lady's family with the recommendation. There used to be a broker to search for partnership and propose it to every family about the match. He even gone about as a moderator, likewise would propose an appropriate date and hour for the union with happen in the wake of coordinating the lady of the hour and the man of the hour's introduction to the world outlines, he further additionally would encourage in choice of the setting reasonable for every family. In Indian Weddings the lady's family was the host for the capacity. In China the procedure started with an intricate proposition to be engaged and acknowledgment. This procedure was put in the hands of a go-between, who went about as a cradle between the two gatherings †a job like that of a realtor today. The significant gatherings in proposition and assurance to be wedded exchanges were the guardians of the forthcoming lady of the hour and man of the hour, instead of the lady and man of the hour themselves. â€Å"Marriage was for proceeding with the tribal line and making coalitions between families â€; too significant an obligation to be left in the rash hands of the young,† Costa clarifies. † When the boy’s guardians recognized a reasonable lady of the hour to-be, they would send the go-between to introduce blessings to the girl’s guardians and to sound out their sentiments about the match. On the off chance that the proposition was generally welcomed, the go-between would get the date and hour of the girl’s birth recorded on a proper report. The groom’s family would put this archive on the tribal raised area for three days. On the off chance that no unpropitious signs, e. g. fights between the guardians or lost property, occurred inside that time, the guardians would give the data to a prophetic master to affirm that the young lady and their child would make a decent match. On the off chance that the boy’s family saw the horoscope as positive, they gave the boy’s birth date and hour to the go-between to bring to the girl’s family, who might experience a similar procedure. Simply after the two results were positive, would the two families orchestrate to meet. At last eye to eye, every family assessed the other as far as appearance, training, character, and social position. On the off chance that both were fulfilled they would continue to the prearranged engagement. Since these is a desk work having an examination of the two nations wedding convention it must have the dresses they wear, the embellishments the have, the significance if averything they do and the mysterious implications which I’ve discovered that are immeasurably critical to the individuals of the two nations. Let’s start with their garments or dresses they wear. In Chinese Red is integral to the wedding subject of China. It implies love, euphoria and success and is utilized in an assortment of courses in Chinese wedding conventions. The bride’s wedding outfit is frequently red, just like the wedding solicitations, and wedding blessing boxes or envelopes for money endowments. Indeed, even the lady of the hour and groom’s homes are enriched in red on the big day while in India, Indian ladies sport pink and red saris on their big day, embellishing themselves excessively with however much gems as could be expected. In these two nations it is essential to know their crystal gazing, in the event that they are good to one another. Since they accept that having the good horoscope implies they will have inexhaustible life ahead. As indicated by the reference book titled Americana, the Hindu marriage ritual opens with supplications by a Hindu cleric. The minister pins one finish of concentrated material to the lady of the hour and groom’s attire while the opposite side is on the blocks as an image of solidarity. The couple at that point stroll around the holy region. After the seventh time, the fixing of agreement is finished. The Ceremony may keep going up to two hours. Toward the end an entire coconut is broken as the cleric favors the couple. hile in China, scarcely any strict services are today in either Communist or Nationalist China. Relationships frequently happen in open lobby. The ceremony is essentially a declaration with a couple’s marriage by their quality before at any rate two observers. The marriage is then recorded with the state specialists. In Indian culture organized relationships have a history since fourth century. The way of life of organized relationships has still endure modernization and industrialization in India. Antiquated occasions, the relationships occurred while the couple was extremely youthful. Truth be told, the kid's folks scanned for a coordinating collusion for him in his preadolescent age and afterward moved toward the young lady's family with the suggestion. There used to be a go between to search for collusion and propose it to every family about the match. He even gone about as a mediator, additionally would recommend a reasonable date and hour for the union with happen in the wake of coordinating the lady of the hour and the husband to be's introduction to the world outlines, he further likewise would encourage in choice of the setting appropriate for every family. In Indian Weddings the lady of the hour's family was the host for the capacity. While in Chinese systemization of evidently previous components of customary Chinese wedding function is commonly credited to researchers of the Warring States time frame , 402-221 B. C. Three admired writings, The Book of Rites, The Book of Etiquette and Ceremonial, and the Baihu Tong plot the Three Covenants and the Six Rites, that were viewed as fundamental components of a marriage. Notwithstanding, the full ceremonial was confounded to such an extent that even inside the range of the Warring States time frame, the manners experienced changes and rearrangements. What stayed steady were the main targets: joining and upgrading the two families and guaranteeing progression with various relatives. Respect to guardians and precursors, signs to empower fruitfulness and riches, budgetary and social commitments shrunk by the two families at the pre-wedding assurance, broad blessing giving decorum, and the bride’s consolidation into her husband’s family are repeating components. Since these are the most fundamental thing in their wedding conventions, it is as yet being rehearsed by them. I have discovered that they have some correlation however Indians are Hindus and Chinese are Buddhists, for instance with their mysterious methods. Yet, I can say that the Indians has a larger number of arrangements than Chinese and furthermore, China’s marriage are more straightforward than with the Indian individuals. The Chinese practices the monogamy marriage while the Indian practices the polygamy. In any case, what’s significant with the two nations is to have their wedding done and to have it in favored manner by the minister and under their GODs as per their religion. Reference http://www.indianetzone.com/2/history_indian_wedding.htm The most effective method to refer to Comparison of Wedding of India and China, Essay models

Art is Everywhere!

Art is Everywhere! [by Emma Frank 15] Before I first visited MIT, I envisioned it as a sterile place. Labs stacked on top of classrooms and everything having its place and assigned number. It didnt seem like a place where Id be bombarded with art from the most unlikely of places. But it is! And after a tour of MITs public art through my freshman advising seminar 21M.A12 (Arts at MIT), Im flabbergasted at the huge amount of art we have on campus, and some things I never realized were art. Now, MIT officially recognizes ninety pieces as public art, and I only saw maybe ten pieces on my tour, so youre just going to get the highlights (as defined by me) here. If youd like to peruse the entire collection, check out http://listart.mit.edu/public_art for virtual tours and more information on the individual pieces. Public art at MIT took off during the Cold War as a way of humanizing the scientists who lived and worked there (AKA keeping people from having that same first impression I had). With the Percent for Art program instated in 1968, any new building project or renovation allots up to $250,000 to commission art for the space. One of the most recent of these pieces is located in the Koch Center and its called Through Layers and Leaves (Closer and Closer) by Martin Boyce: Photo Emma Frank This is the best photo I got that captures the scale of this piece. This is an example of the space relating heavily to the work. The wall sculpture itself is inspired by a photo of four concrete trees from a book on French Modernist gardens from 1925, but the title and the concept of the work relates to the Koch Centers purpose as a cancer research center. Boyce sees finding the cure to cancer as a matter of being able to recognize patterns and to look through the layers and leaves of the disease. Another really interesting thing? See the grate in the bottom right of the photo? Theres three of them spaced along the wall. And within the grate pattern, each one spells out closer and closer. Its not something youd notice unless someone told you, or you spent a lot of time looking at the patterns Boyce created. Photo Emma Frank You have no idea how long I stared at this thing until I found the word closer. Youre welcome. Next up is a piece that Im quite familiar with. Mostly because its right outside East Campus and I see it every day on my way to classes. Its called Transparent Horizon and its by Louise Nevelson: Photo Emma Frank I apologize for the strange lighting and composition of this photo. My only excuse is that it is really hard to take a proper photo when youre trying to simultaneously listen to the guide, set up your photo, and not get left behind. The piece is supposed to suggest botanical shapes. Its actually two older pieces put together and edited to create a new piece. When it was first being installed, there was some controversy over the piece and its infringing on the students living space, but nowadays it has just sort of blended into the general landscape of East Campus. Im ashamed to say that I hadnt really noticed it before it was pointed out to mewhoops. Speaking of not noticing things, did you know that benches can be art? And that they can have really cool stories behind them? Neither did I! In the Wiesner Building are some benches done by Scott Burton. I know, youre about to tell me that Im going crazy to think that of all things, benches can be interesting. But these are controversial benches! And benches I also neglected to take a picture ofso have a picture from the internet! Photo Steve Rosenthal http://listart.mit.edu:8080/Obj1657$15 See the curved things in the center of the photo? Those are the controversial benches. I.M. Pei originally designed the space to be all angles and no curves. But youll note that on the left there are some balconies that echo the curves of Burtons benches. Well, Burtons whole point in making his benches curved in a square and angular space was to make them stand out. He wanted them to have a dialogue with the space by being a disruption and making you feel uncomfortable with them (theyre weirdly leveled and spaced). Needless to say, when the plans got changed, Burton was less than pleased. Our tour guide told us that he can still be pleased that they are a disruption since the benches get really cold during the winter and its a pain to sit on them. In the same space is a piece called Here-There by Kenneth Noland: Photo Emma Frank This is one of my favorite pieces, its brilliant to just stand in front of it and look up and take it in. Im a big fan of color, so its not a surprise I like this piece. Its actually a mural painted directly onto the metal panels, and if you look closely, you can see the actual brush strokes. For a piece that so massive and exact, seeing the brushstrokes made it just a little more human to me. It makes it easier to imagine a person creating this piece, instead of just a machine. This next piece is located in the Stata Center. Its called Non-Object (Plane) by Anish Kapoor: Photo Emma Frank I really like this photo because you manage to get a sense of how the work relates to the space. Its made out of mirror-polished stainless steel, a material Kapoor works with often. Its really interesting because its a piece that encourages you to interact with it. Its sort of like an artistic funhouse mirror. I found it fun to walk around it and see how it changes with the light and angle that you view it at. Id never noticed it before since I only have one class in Stata, and its something you could easily walk by without realizing what it was. It doesnt really invade the space, but rather compliments it. Finally, we have my favorite piece. Mostly because I spent a lot of time there before the tour and didnt realize that what I was sitting on as I worked on a Pset was art. This is Sol LeWitts Bars of Color within Squares (a very inspired title, I know): Photo Emma Frank I envy the people who work in the labs that surround this piece. It must be really cool to look out and see this all the time. Often, I come to this place as a quiet place to work. Theres always a lot of light coming in, and if I want to space out for a little while, its a pretty interesting place to stare out into space. Sol LeWitt was known for his wall drawings where he meticulously explained how things were to be set up. He believed that as long as you followed his instructions for works, you could have your own Sol LeWitt piece. This is in a really cool space that sort of encapsulates building 6C and the physics department. You can view it from a lot of different angles since theres balconies set up all around the work. I definitely suggest taking some time to walk around the space, its a really cool place to just sit and think. So, why did I bother writing a whole blog post on public art? Because I didnt even realize that some of the things I saw everyday were art. Its easy to think of MIT as a cold, heartless institution where science reigns supreme, but in reality, its a place where art and creativity is encouraged. Art brings life to a lot of spaces here, and the stories behind some of the art are fascinating. Public art has the task of relating to where its placed, and public art at MIT reflects how artists see our campus. MIT is a mishmash of buildings and styles and the art here mirrors that. As a freshman, Im still finding new places and things all the time and Im just beginning to realize how varied and unique a place this is. So the next time you come to MITs campus, take a moment to go find some of these works or the many others I just didnt have time to write about. I hope youll have as much fun as I did discovering all of these pieces.

Public Administration - 1077 Words

Midterm Essay: Classical Organizational Theory Liberty University February 5, 2014 Midterm Essay: Classical Organizational Theory Classical Organizational Theory deals with the systematic processes necessary to make bureaucracy more efficient and effective. Name three scholars that are credited with the development of classical organization thought that most correctly fit into this definition of Classical Organizational Theory. What were the basic arguments articulated by each in their contributions to the development of Classical Organizational Theory? Classical organizational theory supports two views. Scientific management which focuses on managing work and employees and administrative management which addresses issues which†¦show more content†¦Another point is the selection of personnel which deals with training, teaching and developing workers. Another point is management cooperation which deals with how managers work with employees to ensure that all assigned work is done according to the principles of the plan and functional supervising which deals with the planning, organizing and decision-making activities and how workers perform their jobs. Henri Fayol was an Engineer and French industrialist. He recognizes the management principles rather than personal traits. Fayol was the first to identify management as a continuous process of evaluation. Fayol developed five management functions. These functions are roles performed by all managers which includes planning, organizing, commanding, coordinating and controlling. Additionally, he recognizes fourteen principles that should guide management of organizations. Luther Gulick was a specialist in municipal finance and administration. He expanded Fayol’s five management principles into seven functions. These functions include planning, organizing, staffing, directing, coordinating, reporting and budgeting. Max Weber was a German sociologist who first described the concept of bureaucracy, an ideal form of organizational structure. He defines bureaucratic administration as the exercise of control on theShow MoreRelatedPublic Administration967 Words   |  4 PagesPublic administration refers to the officials, institutions and processes involved with implementing the laws, rules and policies passed by legislatures and executive. It was originally a branch of political science, but public administration has developed into a field of study of its own during the 20th century, thanks in part to groundbreaking writings by early scholars in the field. 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However, changing in political and economic context have made it increasingly difficult to determine what constitute the principles, foundations, quality and effectiveness of public administration. (UNECOSOC, 2005) The present report presents some initial thoughts and recommendations about the methodology that canRead MoreA Study Of Public Administration1516 Words   |  7 PagesSince Woodrow Wilson (1889) published the article, â€Å"a study of public administration†, the main question in the field of public administration is how to govern a democratic and political entity. Given public administration conventionally concerns about civil servants and agencies in the executive branch, one among diverse and essential subfields is bureaucracy and organizational theory. In general, the development of studies on bureaucracy and organ izational theory has gone through the period of

What Is A False Memory - 2142 Words

Cherry, K. (2016, March 19). What Is a False Memory? Retrieved April 30, 2016, from https:// www.verywell.com/what-is-a-false-memory-2795193 This webpage presents false memory at a glance. The webpage covers topics relating specifically to false memory, such as the definitions, causes, impacts, and who is affected. The author distinguishes false memory from other forms of memory fallibility. Also, the author indicates the various factors that influence false memory like misinformation, misattribution, existing knowledge, and suggestions from therapists or investigators. Finally, the author concludes that false memory is problematic especially in criminal trials and eyewitness testimony, where false memories are one of the leading causes of false convictions due to false identification of a suspect, or false recollections during interrogations. Verywell is the website from which this webpage was derived from. It is a reliable source for a lot of reasons. First, the content on the we bsite is written by experts like doctors, trainers, and other healthcare professionals. All of the medical facts are well-documented. They are reviewed and approved by board-certified physicians. Second, Kendra Cherry is qualified to write this piece. Cherry is an author and an educator of psychology. She is the author of a book titled â€Å"Everything Psychology† (2nd edition) and has published many articles on diverse psychological topics. In addition, she holds a Master of Science in educationShow MoreRelatedWhat is False Memory Syndrome? Essay789 Words   |  4 Pages False memory syndrome is also called Recovered memory, Pseudo-Memory, and Memory Distortion. False memory syndrome or pseudo-memory is memories of an experience, in which one seemingly remembers that never actually or really occurred. In other words, false memory is a fabricated remembrance of past events that did not really happen. 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It is not uncommon for individuals to fill in memory gaps with what they assume they must haveRead MoreFalse Memory Syndrome1478 Words   |  6 Pagescompared to what is unknown about cognitive functioning, individuals cannot fully grasp the reasoning behind why the brain performs some of the acts it does. Many people daydream, picture themselves recovering lost items in obscure places, or even create stories repeated so much that individuals begin to believe they may have happened; all three of these examples are forms of creating a false memory. Many psychologists have researched, evaluated, and experimented with false memory, which has lead

Is Facebook boosting or hindering communication Free Essays

Is Facebook boosting or hindering communication? Facebook is the most famous commonly used social media. It has become the preferred method for keeping in touch with people. Almost every young person has at least one Facebook account. We will write a custom essay sample on Is Facebook boosting or hindering communication or any similar topic only for you Order Now However useful it might be in social life and education, Facebook brought about a set of new barriers and threats in these areas. There is an irony in the sense that social media, like Facebook, has the ability to make us less social. Doubtless it may be stimulating to feel so connected with others, and et there is no way to deny that underneath this feeling, there is a sense of emptiness. Robin Sharma agrees with that fact in his book The Greatness Guide by saying that the more we are electronically connected, the more we are emotionally disconnected. In other words, while people spend many hours of their days on Facebook chatting, posting status and wishing happy birthdays and engagements to one another, they forget about the importance of conversation in the traditional way. They completely forget about the effectiveness of sitting to dinner with the family or hanging out with friends. In a word, Facebook is gradually robbing people of what distinguishes them as human beings. Not only does Facebook make us less social, but also sometimes conveys a completely different reality about its users. Anyone can hide behind Facebook posts, giving any image they want about themselves and creating an illusion about their personality. They can be whoever they want, depending on the fact that their audiences have no hoice but to be confused, having no verbal communication. So, our only real method of communication is through voice-to-voice or face-to-face communication. It is only through this way that when one hears a tone of voice or looks into someone’s eyes, they are able to know when â€Å"l am okay† does not mean they are okay at all. Thus, without any means of communication but phrases, abbreviations, snippets and emoticons on Facebook, one can never be sure whether these things are accurate representations of the truth. As for education, students, no doubt, owe Facebook a lot for facilitating their education process, but still it is a main contributor to the failure of many of them. Although Facebook plays a role in breaking the ice between colleagues in schools or universities, it wastes much of their time in chatting about trivial matters. It is true Facebook helps students keep updated with the latest news about their studies, even if they are absent from schools or universities. But student rumourmongers ruin verything by spreading so much false news that any news by any student is subject to suspicion, which turns the advantage into a disadvantage. This way Facebook is more of a waste of time for students. Facebook. Now compare this time to the time you spend in real life with your family, friends and your colleagues at school, university or work. Try to make the decision of making the best use of Facebook and try to avoid as many of its disadvantages as possible. Out of my own experience, the time and relations you are going to revive are worth giving a try. How to cite Is Facebook boosting or hindering communication, Papers

Is Facebook boosting or hindering communication Free Essays

Is Facebook boosting or hindering communication? Facebook is the most famous commonly used social media. It has become the preferred method for keeping in touch with people. Almost every young person has at least one Facebook account. We will write a custom essay sample on Is Facebook boosting or hindering communication or any similar topic only for you Order Now However useful it might be in social life and education, Facebook brought about a set of new barriers and threats in these areas. There is an irony in the sense that social media, like Facebook, has the ability to make us less social. Doubtless it may be stimulating to feel so connected with others, and et there is no way to deny that underneath this feeling, there is a sense of emptiness. Robin Sharma agrees with that fact in his book The Greatness Guide by saying that the more we are electronically connected, the more we are emotionally disconnected. In other words, while people spend many hours of their days on Facebook chatting, posting status and wishing happy birthdays and engagements to one another, they forget about the importance of conversation in the traditional way. They completely forget about the effectiveness of sitting to dinner with the family or hanging out with friends. In a word, Facebook is gradually robbing people of what distinguishes them as human beings. Not only does Facebook make us less social, but also sometimes conveys a completely different reality about its users. Anyone can hide behind Facebook posts, giving any image they want about themselves and creating an illusion about their personality. They can be whoever they want, depending on the fact that their audiences have no hoice but to be confused, having no verbal communication. So, our only real method of communication is through voice-to-voice or face-to-face communication. It is only through this way that when one hears a tone of voice or looks into someone’s eyes, they are able to know when â€Å"l am okay† does not mean they are okay at all. Thus, without any means of communication but phrases, abbreviations, snippets and emoticons on Facebook, one can never be sure whether these things are accurate representations of the truth. As for education, students, no doubt, owe Facebook a lot for facilitating their education process, but still it is a main contributor to the failure of many of them. Although Facebook plays a role in breaking the ice between colleagues in schools or universities, it wastes much of their time in chatting about trivial matters. It is true Facebook helps students keep updated with the latest news about their studies, even if they are absent from schools or universities. But student rumourmongers ruin verything by spreading so much false news that any news by any student is subject to suspicion, which turns the advantage into a disadvantage. This way Facebook is more of a waste of time for students. Facebook. Now compare this time to the time you spend in real life with your family, friends and your colleagues at school, university or work. Try to make the decision of making the best use of Facebook and try to avoid as many of its disadvantages as possible. Out of my own experience, the time and relations you are going to revive are worth giving a try. How to cite Is Facebook boosting or hindering communication, Papers

Organizational Behavior of Resonus Corporation †Free Samples

Question: Discuss about the Organizational Behavior of Resonus Corporation. Answer: The case is about departmental problems in Resonus Corporation. Frank Choy an engineering director responsible for ESD and research department felt that the interdepartmental battles were wearing him down. He realized that employees got most of the blame rather than credit for issues that could be avoided if the right protocol was followed. He tracked the problem to the corporates CEO, Bill Hunt, who responded to the problems with a lack of urgency, urging employees to remain civil and telling them to learn to get along better. He even fired the previous engineering director due to constant disputes in the office. He thought that the problem was not on how the departments were run but how people learn to fit into the existing organizational culture. Hunt insisted on promoting informal relationships between managers since the companys founder had groomed him to maintain organizations family spirit. The informal relationships has led to poor organizational response to departmental heads. For instance, a research director in the corporation who directly reports to the CEO, Doc Kalandry has never felt the need to acknowledge Chow as his director. Hunt had a close relationship with Doc since his first job in the company was in the research team and he is still very connected to Doc and most employees are aware of it. Hunt even refers to Doc as a living genius and sees his innovations as the companys get way to success. Although everyone seemed to love Docs over enthusiasm about his innovations a few ESD staff felt like his director needed to manage him better. Choy and his team felt that they undergo through constant critique on their work from the production supervisors unlike the higher research team whose explanations are taken without any complaint. ESD team believe that those critiques should be directed to the research team since they are responsible for the design changes. They argue that with the work experience that they have they shouldnt be constantly put in a position to defend their abilities rather they should be getting work done. Latest trouble began when Doc came up with one of his last minute innovation which Hunt endorsed without consulting other departments which were going to be involved in the development and manufacturing process. The innovation was a new nano processor technology that was to be installed in the hearing-aid product. The case demonstrates that the departments in the organization lacked coordination and unity in identifying new inventions that were efficient and cost effective. Hunts leadership was biased and he lacked impartiality when it came to dealing with his cronies such as Doc. Even with proven failures in Docs previous innovations Hunt kept on endorsing and favouring him, which brought about agitations from employees. Anyone who brought up the issue was viewed as being aggressive, this was the very reason that Choys predecessor got fired. This resulted to employees getting along with Docs innovations even though they knew it was not possible to deliver the product on time. This kind of behavior eventually led to poor organizational relations that had huge implications to the success of the organization.

M16- Americas Hero! Essay Example

M16- Americas Hero! Essay he M16 has evolved along with American Warfare. The M16 start off with a Research Project funded by the Army. The first model of the M16 rifle was the M16A1 which had many problems. (Wikimedia 1) The next model was the m16a2 which was the successor of the M16A1 that didn’t have the same problems. The following model was the M16A3 which was a newer more advanced M16 compared to the M16A2. (Wikimedia 1) Following the M16A3 was the M16A4 rifle that was even more sophisticated and technologically advanced than its earlier model.America had adopted the M16 and improved it until it became the weapon of choice in modern warfare. The origin of the M16 assault rifle came from the Operations Research Office soon after the end of the Korean war. (Gunpedia 1) This operation was funded at Hopkins University which was sponsored by the United States Army. (Gunpedia 1) In 1963, an American company named Colt received and order of 19,000 rifles for the United States Airforce. (Gunpedia 1) Thus the M16A1 is born. Then in 1966 the United States government put in a large purchase of 840,000 rifles to support the growing number of troops being stationed in Vietnam. Gunpedia 1) The M16A1 proved most ineffective during the war in Vietnam. This was because the M16A1 rifle had a jamming problem and the troops using this weapon were not prepared to clean it and keep it up on its maintenance. (Wikimedia 1) With the occasional jam many casualties occurred.This forced Colt to develop a new weapon that would not retain some of the flaws of the old rifle. Thus the M16A2 was born. This new rifle did not show any of the old rifles problems and was used to replace its older version. Gunpedia 1) As the years went by many innovations and improvements were made to the M16A2 assault rifle which led to the creation of the M16A3 and the M16A4 rifles. (Wikipedia 1) These newer models both came out by 1996. (Gunpedia 1) This was how the M16 came to be in America. The M16A1 was the first model of the M16 assault rifle used by the United States. The Country of origin of this rifle was the United States of America. The designer of this weapon was Colt which is an American company. This weapons production began in 1963 in The United States. (Gunpedia 1) The M16A1 shot a 5. 56 millimeter bullet. Mcnab 282) The M16A1 first saw combat in Vietnam in 1963. (Gunpedia 1) The Rifle was used in jungle warfare against the Vietnamese. The gun was ineffective because of a jamming problem; this was cause of many casualties. (Gunpedia 1) Although the M16A1 had its flaws it was used to replace the M14 as the United States standard infantry rifle. The M16A1’s successor was the M16A2. America then upgraded to the M16A2 rifle.This rifle fires rounds at 5. 56 millimeters. (Mcnab 282) This rifle had adjustable fire rate ranging from semi-automatic to three round burst. This rifle was engineered and first put in use in the early nineteen eighties. Gunpedia 1) There were numerous upgrades do ne to the M16A2 to increase its effectiveness on the field. The first upgrade was a windage adjustable sight that was placed in the rear of the carrying handle which was innovated by the United States. (Wikimedia 1) The next innovation was an adjustable stock that extended from five to eight inches for maneuverability; this was also an American improvement. (Wikimedia 1) Also the gun was made heavier to carry the bullet better. Also there was an added case deflector for left handed shooters. (Gunpedia 1) The hand deflector was made cylindrical to accommodate for left handed shooters. Gunpedia 1) Both of these advancements had been made by American companies. Although this was a huge advancement it was mainly used only in National Guard and the Navy by Navy Seals for Special Ops missions. (Wikimedia 1) The next model manufactured was the M16A3. The M16A3 was the Rifle model made after the M16A2. The M16A3 had a semi-Automatic mode and also supported a fully automatic setting as well. (Gunpedia 1) This rifle is commonly referred to as a M16A2 with a fully automatic setting and a Picatani rail. (Wikimedia 1) This is a common misconception because the M16A3 supports many more features than just these to.Although this was a new model it wasn’t widely used in the United States military. This was probably due to its almost identical features with the M16A2. This gun was mostly used by the Navy Seals and was ordered along with a larger batch of M16A4s. (Gunpedia 1) Colt was the manufacturer of this weapon. (Wikipedia 1) After these models of production were put out in 1994 a new model of M16A4s came in. The M16A4 is currently the newest model of the M16s. This rifle’s country of origin in the United States of America. (Wikimedia 1) The designer of this weapon of this weapon was the American company Colt.This weapons production started in 1994 in America. (Gunpedia 1) The A4 shoots a 5. 56 millimeter bullet and is gas operated. (Mcnab 282) This weapon is being used in Iraq and Afghanistan today. This rifle is the most modern rifle with the most advancements in the line of M16s. Although this is the best of the best when it comes to M16’s this rifle is being phased out of the U. S. military by 2010 being slowly replaced by the M4 Carbine. (Wikimedia 1) America had started with nothing and built its way to the most modern weapons we use today. America had started off with the problematic M16A1 rifle.After an advancement to the firing mechanism America had created the M16A2 rifle. With many improvements to the M16A2 rifle came the M16A3 and the M16A4 Rifles which are the most modern version of the M16 assault rifle today. America has made much advancement in technological warfare.Mcnab, Chris. Twentieth-Century Small Arms. Metro Books. New York, NY 1001, 122 fifth avenue, 2001. gt; (source 1) lt;†M16 Rifle† Wikipedia. 2010. Wikimedia Foundation, Inc. http://en. wikipedia. org/wiki/M16_rifle

The United States as the Worlds Peacekeeper essays

The United States as the World's Peacekeeper essays My original speech topic before the Trade Center and Pentagon attacks was should we be the worlds peacekeepers and I was going to slant it towards the no side. Then in the week after, I realized the answer was a resounding yes...for several reasons. 1. Because we can. That isnt just about ego, but also about economy. We are the elder brother and sister of the world, and we bail out our younger relatives when they need help. No questions asked. 2. Because in this country we believe EVERYONE has the right to freedom, not just Americans. So well fight for the freedom of all people, everywhere. Sometimes this means fighting with the military, but just as often it means boycotting soccer balls made by child labor in Bangladesh. Americans vote with their hearts, and once weve tasted freedom it is so intoxicating we feel as excited as a new convert to a cult, we want to share the secret with the world. Numerous benefits also come along with helping countries when in need, for example, in the worst-case scenario, if a third world war was to begin, we would have almost nothing to worry about, who would think of striking the country with the most allies? America is one of the most powerful countries in the world and if anyone should have the courage to take on Americans in general, then let them try their best, we may have some casualties, but how would we prove our authority without having the challenge present itself. This may seem condescending, but for the most part, even with the destruction of federal buildings on September 11 and thousands of fatalities, the country will go on, Americans will not allow our government to be brought down by these arrogant events. There are critics that believe that America should not get involved in matters that have no direct impact on the United States, but dont Americans believe that all men are entitled to life, liberty an...

Philedelphia Essay Example | Topics and Well Written Essays - 500 words

Philedelphia - Essay Example Popularly known as the Global Exhibition of Arts, the culture associates with the manufacture of mine and soil products. The exhibition is the first most important universal Fair held in the United States, which took place on 10th May 1876 occupying a two hundred and eighty five acre tract of the Fairmount Park thus overlooking the river Schuylkill (Exhibition, 2012). The twenty seven year old German immigrant by the name of Hermann J. Schwarzmann had an opportunity to design the fairgrounds that he did exclusively. The ground hosted thirty seven nations and many industrial exhibitions which occupied over two hundred and fifty pavilions belonging to individuals (Exhibition, 2012). The exhibition attracted almost nine million visitors while the population of the United States was forty six million. The exhibition had a lasting accomplishment as there was the introduction of industrial Universal power in America. The industrial power concealed the potency and production of many industrialized nations. Philadelphia became the central city the industrial and cultural practices in America (Exhibition, 2012). The visitors attending the exhibition loomed the fairgrounds mostly from east by means of either horse-drawn trolley or the railway across the today Gerald Avenue Bridge (Exhibition, 2012). There was a glass and steel dome of the Memorial Hall on the Schuylkill river near the exhibition grounds whose flag- studded the towers of the major building grew as the wooded slope of Fairmount Park. The complete site and size of the structures are breathtaking in their natural setting (Exhibition, 2012). As advised, the visitors arrived from the Railway of Pennsylvania Depot recognized as the Parkside Avenue today. They were to arrive promptly for the opening at 9:00 AM, and they had to pay fifty cents for entrance

MAF307 EQUITIES AND INVESTMENT ANALYSIS Essay Example | Topics and Well Written Essays - 1000 words

MAF307 EQUITIES AND INVESTMENT ANALYSIS - Essay Example The strategic analysis of the group indicates that with continued development of new initiatives and business products, the group is likely to expand its client base by entering new markets. The company’s salary packing business continues to provide an annuity stream of income that further allows cross-selling of company’s other products such as leasing services. The company has a very strong balance sheet and cash flow position that gives it opportunity to choose inorganic expansion route. The company’s revenues from core activities experienced 12.6% to $161.50 million at the end of December 2012, with net profits rising over 19.3%. The company announced the gain in gross revenue and profit for the year June 2013 but a proposal from the Labour government shook company’s future earnings capacity causing the company’s share price to plunge by over 55% in the middle of July 2013. Background of Share Price Crash McMillan Shakespeare’s Finance gr oup share price almost halved since the government flagged changes to current laws of fringe benefit tax (FBT) that has created uncertainty in the markets. The company’s trading was suspended for a week and when it resumed trading the share prices crashed by over 48% to $7.99 wiping away almost $549 m of shareholders’ wealth from the markets (Australian Associated Press, 2013). Due to this reason the company’s management requested for an extension to halt trading which is viewed by many analyst as a desperate move by the management to avoid such huge amount of losses and save shareholders’ wealth from volatile and uncertain markets. The Australian Securities and Investment Commission have however rejected the company’s plea of halting trading. (Source: ASX, 2013) The company has criticised the government’s recent decision to tightening FBT guidelines especially on salary package and car leasing for the share price crash and uncertainty in ma rkets. The panic among the investors was evident since the proposed changes to FBT guidelines tighten fringe benefit taxes on salary packaging and car leasing. The investors in the market expected the revenues of the company to be adversely affected from the government’s decision since the company’s primary source of revenues is generated from car leasing and salary packages. This negative outlook on the company’ future earning capacity from the tightening of FBT created panic in the broader markets that led to overselling of company’s stocks in Australian Stock Exchange. Thus, it can be said from the above discussion that a chain of events starting from the government’s decision to tighten FBT guidelines, the same decision to adversely affect profitability of the company, negative sentiments among the investors in the market regarding company’s future, and huge sell of the Finance Group’s MMS stocks after a week’s inactive tra ding, ultimately caused the company’s share prices to plummet by over 55% in the mid of July 2013. Reasons behind Dramatic Price Change The company under observation derives almost 50% of its revenues from two major segments namely Asset Management and Group Remuneration Services. But from the analysis of financial statements of the company it is apparent that over 70% of its total earnings are generated from the revenues of group remuneration, which is almost three

Benefits Of Ict In Smes Information Technology Essay

Benefits Of Ict In Smes Information Technology Essay Introduction Research indicates that Information and Communication Technology (ICT) offers promising opportunities for organizations to meet the challenges of an ever-changing environment (Kapurubandara and Lawson, 2006). ICTs are recognized as key tools in management processes, having a remarkable potential to contribute to sustained competitive advantage for businesses (Ion and Andreea, 2008). In Small and Medium Sized Enterprises (SMEs), ICT can be used as a business tool to reduce costs, create stronger links with customers, innovate and facilitate market niche (Kutlu and Ozturan, 2009). Although there are difficulties associated with the use ICT in SMEs, however this study highlights the benefits associated with the use of ICT a Nigerian SMEs and identifies some problems facing the Nigerian SME sector. Significance of SMEs The importance of Small and Medium Sized Enterprises (SMEs) cannot be overlooked in the economic development of any country since SMEs play a critical role in every countrys economic development and Nigeria is no exception. SMEs have been fully recognized both in developed and developing countries as the main engine of economic growth and a major factor in promoting private sector development and partnership (Okongwu, 2001). SMEs are often seen as vital for the growth and innovation of dynamic economies as they create employment (Mutula and Brakel, 2006). They are flexible and can adapt quickly to changing market demands as supply situations help diversify economic activity that has significant contribution to imports and exports (Ongori, 2009). Thus, SMEs contribute more and more to the national and international economies of the world. According to Wattanapruttipaisan (2003), the significance of SMEs for growth, productivity and competitiveness of the economies in both developed and developing countries is universally recognized since SMEs contribute to improved living standards, bring about substantial local capital formation and achieve high level of productivity and capability. They are recognized as the principal means of achieving equitable and sustainable industrial diversification and dispersal. The contributions of SMEs to the Nigerian economy are not contestable as about 10% of the total manufacturing output and 70% of the industrial employment are by SMEs. SMEs also promote industrial and economic development through the utilization of local resources, production of intermediate goods and the transformation of rural technology (Aina, 2007). Nigerian SMEs do not only provide employment and income for majority of its citizens but also, SMEs are acknowledged as the breeding ground for domestic entrepreneurial capabilities, technical skills, technological innovativeness and managerial competencies for the private sector development (SMEDAN, 2005, Aina, 2007). The benefits of SMEs to any economy are easily noticeable as SMEs are known to contribute to the development of several economies in terms of output of goods and services, creation of jobs at relatively low capital cost, especially in the fast growing service sector and they provide a vehicle for the reduction of income disparities thus developing a pool of skilled or semi-skilled workers as a basis for the future industrial expansion (Aina, 2007). SMEs also improve forward and backward linkages between economically, socially and geographically diverse sectors of many economies and provide opportunities for development (SMEDAN, 2005). Therefore, the development of SMEs is an essential element in the growth strategy of most economies and holds particular significance for Nigeria. SMEs have been defined by SMEDAN as: Size Category Employment Assets (N million) excluding land and building 1 Micro Enterprises Less than 10 Less than 5 2 Small enterprises 10-49 5- less than 50 3 Medium enterprises 50-199 50- less than 500 (SMEDAN, 2005) In Nigeria, SMEs cover the entire range of economic activity within all sectors and share a number of common problems. These problems as identified by the Small and Medium Enterprises Development Agency of Nigeria (SMEDAN) and other similar studies include low market access to credit, poor information flow, discriminatory legislation, poor access to land, weak linkages among different sectors, weak operating capabilities in terms of skills, lack of knowledge and attitudes, lack of infrastructural facilities among others. Information and Communication Technology (ICT) Information and Communication Technology (ICT) refers to a wide range of computerized technologies. ICT is any technology that enables communication and the electronic capturing, processing and transmission of information. These technologies include products and services such as desktop computers, laptops, handheld devices, wired or wireless intranet, business productivity software such as text editor and spreadsheet, enterprise software, data storage and security, network security and so on (Ashrafi and Murtaza, 2008). In Nigeria, commonly used ICTs include Personal Digital Assistants (PDAs), Automated Teller Machines (ATMs), mobile phones, and smart cards. The Role of ICT in SMEs In the present knowledge-based economy, it is important for SMEs to adopt processes that would enable them provide services that would bring about competitive advantage. ICT has a significant positive impact on organizational performance (Maldeni and Jayasena, 2009). ICT is crucial to SMEs as it is a major catalyst and enabler of organizational change (Hazbo et al, 2008). Modern businesses are not possible without the use of ICT which is having a significant impact on the operations of SMEs and it is claimed to be essential for the survival and growth of economies in general (Berisha-Namanil, 2009). ICTs provide opportunities for business transformations (Chibelushi, 2008). It also provides SMEs the opportunity to conduct business anywhere (Jennex et al, 2004). It is commonly accepted that ICT provides many potential benefits to organizations so as to make them more efficient, effective and competitive (Fink and Disterer, 2006). ICT increases richness and reach (Evans and Wurster, 19 97). This refers to the way companies communicate, collaborate, conduct transactions internally with their customers, suppliers and distributors via the internet and the ability for local SMEs to participate in the digital economy (Golding, et al, 2008). According to Erumban and de Jong (2006), ICT has created a revolution by making the world seemingly smaller and improving potential economic growth. Pavic et al (2007) argue that SMEs have the opportunity to achieve a competitive advantage from the advances in ICT through innovation, marketing, efficiency gains, better quality and customer responsiveness. Also, Levy et al (2002) found some evidence which shows that SMEs act proactively in relation to the use of ICT. The European Commission (2008) state that SMEs could use ICT in order to grow and to become more innovative. The use of ICT in SMEs should be encouraged as it can help to improve technical and managerial skills, making available e-business solutions for SMEs and addressing the high cost of ownership of ICT equipment. Also, Love et al (2004) ascertains that the use of ICT provides many benefits to SMEs at different levels (operational level, tactical level and strategic level). In addition, Ongori (2009) states that the use of ICT would help change the way businesses operate in this era of globalization by changing business structures and increasing competition, creating competitive advantage for businesses and by changing business operations. Therefore, SMEs must have an ability to compete and dynamically respond to rapidly changing markets as it plays a significant role in an organizations growth and success. According to Kapurubandara and Lawson (2006), for survival in a competitive global economy and staying abreast, it is apparent that SMEs embrace ICT as it is becoming imperative for SMEs to gain competitive advantage and for stability in international markets. This implies that there are several benefits associated with the use of ICT. Benefits of ICT in SMEs The benefit of ICT cuts across all sectors of the economy and all the fields of human activities (Udo and Edoho, 2000). ICT can improve the standard of living and enhance business operations as well as organizational efficiency (Udo and Edoho, 2000). Appropriate use of ICT can assist SMEs to gain competitive advantage by reducing costs and improving core business processes. According to Brynjolfsson and Hitt (2000), the use of ICT can help to cut down the costs of coordination, communication, information processing and also enable efficient service provision at lower cost. ICT is a strategic tool that enables users to be efficient and effective (Sewanyana, 2009). The diffusion of ICT in many countries by different sectors of the economy have been found to have direct positive impact on the organizations efficiency and have led to more rapid acceleration of development in these countries (Achimugu et al, 2009). In Nigeria, preliminary investigations show that only few SMEs presently u se ICT. However, there has not been a formal study to ascertain the impact of ICT in these organizations. According to Fullanteli and Allegra (2003), ICT offer enterprises a wide range of possibilities for improving their competitiveness. They provide mechanisms for getting access to new market opportunities and specialized information services such as distance consulting, continuous training, new advisory modes, and so on. Organizations can exchange real-time information and build closer relationships with their customers, suppliers and business partners; customer can receive immediate feedback that allows companies to react fast to changing customer demands and recognising new market niches. This means that organizations that are able to exploit the potentials offered by ICT can handle innovative processes such as Supply Chain Management (SCM), Customer Relationship Management (CRM) and Knowledge Management (KM) more effectively (Fullanteli and Allegra, 2003). Since, ICT has been described as critical to the competitiveness and growth of SMEs (Apulu and Latham, 2009), it is important for it to be applied in the relevant manner in order to reap the far-reaching payoffs of ICT. Shiels et al (2003) state that technology would not lead to business growth except it is aligned with a business strategy. This means that having the right technology in the right place and at the right time would assist to improve business performance and also aid competitiveness and sustainability (Swift, 2009). Once ICT is integrated into a business process, it becomes a useful tool in many stages of the value chain (Swift, 2009). The use of ICT in SMEs helps to improve communication ability to exchange data, teamwork, customer relations services, market share and so on. It allows companies to obtain, process, accumulate and exchange information (Ion and Andreea, 2008). Another benefit of using ICT in SMEs is the fact that high efficiency is obtained in business transactions due to a fast and accurate processing of information (Ion and Andreea, 2008). Lal (2005) further states that web-enabled services increase the competitiveness of SMEs because they change the relationship with customers by creating a stronger link between firms and clients. The use of ICT in SMEs facilitates cooperation within the company, between the company and other firms. Similarly, Swift (2009) states that SMEs benefit from the use of ICT as it increases productivity, efficiency of internal business and operation and connects SMEs more easily and cheaply to external contact. Other benefits include increasing business competitiveness; vertical integration with other related initiatives, meeting stakeholders of various institutions; networking with other parties; creating of an enabling environment and the development of an internal competence in capturing market opportunities (Swift, 2009). Hence, the investment in ICT will result in increasing SMEs rates of sales and share of market, improve their Return on Investments (ROI), reduce cost and assist them to develop new products and/or markets. Chowdhury and Wolf (2003) argue that SMEs use ICTs both as input in the production process and in the transaction process selling their products or acquiring inputs. ICT enhances enterprise performance through indirect cost savings such as labour costs, increased labour productivity and direct cost reduction of firms input (Chowdhury and Wolf, 2003; Love et al, 2006). On top of these short-run impacts of ICT in the production process, the use of ICTs in the transaction process can foster input and output market expansion. However, in the long run ICT may have a bigger impact as it can completely restructure the production process and transaction methods and also increase flexibility and improve outputs (Chowdhury and Wolf, 2003). In order words, it can be concluded that ICTs can influence the performance of an enterprise in multifaceted ways. In addition, ICT has been widely perceived as major tools for kick-starting ailing economies and consequently in assisting developing societies to catch up with the developed world. ICT can assist groups that have lost out of the mainstream of development (Obijiofor et al, 2005). ICTs have valuable potentials for developing SMEs through more effective use and better integration in their business processes. This will bring about a change among SMEs and make them more competitive, innovative and also generate growth (Obijiofor et al, 2005). Nevertheless, several factors hinder SMEs from fully realizing these benefits. According to Liedholm (2002); Ducombe and Molla, (2009), SMEs especially in Africa suffer from many constraints related to an unfriendly policy and regulatory environment, lack of finance, lack of skills, access to markets and market information, lack of infrastructure among others and Nigerian SMEs is no exception. Problems of SMEs in Nigeria Several problems are militating against the development of SMEs in Nigeria. As a developing economy, one of the most worrying among these constraints is the issue of funding (Aina, 2007). This is because most banks are afraid of funding SMEs for the reason that they want to minimize their risk profile. Also, the Nigerian economic situation is not very attractive to investors (Aina, 2007). This forms a major constraint to SMEs growth in the country. In Nigeria, there is the problem of inadequate and inefficient infrastructural facilities, which tend to escalate costs of operation as SMEs are forced to resort to private provisioning of utilities such as water supply, electricity, and so on (Udechukwu, 2003). Other problems include lack of adequate credit for SMEs traceable to the reluctance of banks to extend credit as well as inadequate collateral by SME operators, weak demand for products arising from low and declining consumer purchasing power and lack of patronage of locally produced goods by those in authority (Onugu, 2005). All these problems hinder the effective use of ICT in Nigerian SMEs. Electricity constraint is a major factor that affects the use of ICT in Nigerian SMEs. In many rural areas, there are no electricity supplies; while in the towns and cities where there is electricity, its presence is limited. Electricity generation and distribution therefore negatively affect the diffusion levels of ICT in the country (Akpan-Obong, 2007). Nigerian population lacks access to electricity. Therefore unless power supply is stabilized, as well as expanded to the rural areas, electricity is likely to remain a key factor hindering the development of SMEs in Nigeria. There is also the problem of multiplicity of regulatory agencies and taxes which has always resulted in high cost of doing business, poor management practices and low entrepreneurial skill arising from inadequate educational and technical background of many SME owners (Udechukwu, 2003). Similarly, developmental policies weigh in favour of large firms and sometimes foreign owned firms leaving SMEs in a distressed and vulnerable position. Corruption, lack of transparency, very high bureaucratic costs and lack of government interest in supporting the roles of SMEs in national economic development and competitiveness. The most worrying of all among these challenges is funding. Most SMEs enterprises are not attractive prospects for banks as they want to minimize their risk profile. Also, In Nigeria, provision of public infrastructure is grossly inadequate and poor (Posu, 2006). Necessary telecommunication services, as public infrastructure, needed for meaningful investment are very expensive and inadequate. Research Method Case studies are the most common qualitative method used in information systems research (Cassell and Symon, 2004; Burns, 2000; Yin, 1993; Orlikowski and Baroudi, 1991). Sauer (1993) is of the opinion that research in information systems is best done by case study. A case study research is useful when a phenomenon and context are not clearly evident (Yin, 2003). It also allows us to study a phenomenon within its natural context (Yin, 2009). Therefore given the exploratory nature of this study, the qualitative case study approach is adopted. According to Yin (1994), case study methodology offers a means of testing existing theories while providing a probable analytic generalization. This study is based on primary research from interviews and secondary research including internal documents and academic sources. The case study was selected based on the size of the company, in accordance with the definition of SMEs in Nigeria and also based upon the post-ICT experience in the company. Semi-structured interviews were used to gather details of the SME. Questions related to the business aspects of the company, drivers for ICT adoption, barriers to ICT adoption, use of ICT, ICT infrastructure, competition and benefits of ICT were asked at some point in the interview. In terms of the analysis of the interviews, notes were compiled during each interview which gave an accurate reflection of the information gathered. In addition, some company documents were reviewed. Furthermore, extensive amount of secondary data was collected and reviewed from various sources which included books and academic journals. A general introduction to the organization involved is provided below , followed by a discussion on the benefits of ICT within the organization. The company in this paper has been given pseudonyms and some details of the company have been shrouded to maintain company confidentiality. Case Study MACO is a small manufacturing company located in Port-Harcourt, Nigeria and was established in 2003. Presently, the company has fourty employees all of which are full time workers. The companys goal is to satisfy its present and future customers by developing level of services superior to those of its competitors. MACOs vision is to satisfy customer needs by providing promt and efficient services and to create a secured and viable engineering solution to its customers. In 2005, the company decided to implement an ICT system called ERP (Enterprise Resource Planning) due to the competitive nature of the market and the need to stand out from the crowd. Another reason behind the companys decision to use the new system was as a result of the challenges MACO was facing with its customers in terms of tendering and purchase processes and in the production capacity planning. The ERP system helps in the companys production capacity planning and control, so that the scheduling and resource allo cation for different projects can be planned ahead before the project begins. The ERP system has given MECO a huge opportunity. The company can now easily target new customers, survive and grow in this competitive climate and also build long term relationships with its customers. Discussion SMEs have been recognized for playing very important roles towards the economic growth, development and stability of several economies. SMEs play a vital role in employment generation and immensely contribute to the Gross Domestic Products (GDPs) of several countries (OECD, 2000). With reference to the case study presented above, it can be said that there are several benefits associated with the use of ICT. ICT offers SMEs a competitive edge over its competitors (for example increase in production capacity planning and control) hence, it is vital for Nigerian SMEs to use ICT. It should be regarded as a critical tool for SMEs competitiveness. Based on the literature review, some major factors that affect Nigerian SMEs are lack of infrastructural facilities and lack of electricity. Furthermore, lack of resources is another major factor. Hence, the Nigerian government should set up different agencies to look into the various problems associated with SMEs in Nigeria. The government can provide an enabling environment in which ICT can realize its full potential. They can help to address the problems and challenges of awareness and infrastructure under- development (Payne, 2001). Nowadays several organizations have moved from manual paper-based to ICTs for internal processing of information, and from telephony to ICTs for external communication. Thus access to ICT has provided people with a foundation for building up and applying knowledge globally and particularly in developing nations (Ani et al, 2007). Through the use of ICT, modern society has been described as an information age and the knowledge economy. In the present knowledge based economy, the use of ICT can to bring the same competitive advantage to small and medium sized enterprises as brought to large enterprises. ICTs are also making it possible for developing countries to participate in the world economy in ways that simply were not possible in the past. Hence, information and communication technologies should be regarded as a strategic tool in SMEs. The use of ICTs in SMEs should therefore, be considered as part of the wider informal to formal transition process for information systems. There is need for SMEs to undertake continuous improvement of their existing processes, products and services. They need to introduce products and services with extended capabilities to create more value for their customers (Hanif and Sajjad, 2009). On one hand, ICT provides all enterprises with a lot of opportunities for their business activities. On the other hand, SMEs have always been considered to be the major economic players and strong sources of economic growth. Therefore, it is apparent that the use of ICT in SMEs is critical in every economy including Nigeria. As a result of Nigerian SMEs not being fully ICT-enabled they are unable to keep up with the pace of globalization. Thus they are deprived of ways by which ICTs can improve it their business processes. ICTs have the potential to improve SMEs business processes as it brings about better insights. Hence, the government needs to address these issues to encourage ICT enabled SMEs. Nigeria can as well leapfrog from its present status of  under development to a fully developed global giant, as it cannot afford to stand alone (Elebeke, 2009). Todays business world has been deeply influenced by ICT and its application among business is widespread. ICT are rapidly changing global production, work and business methods and trade and consumption patterns in and between enterprises and consumers (Alam and Noor, 2009). Also, SMEs are often seen as a vital source of growth and innovation in a dynamic economy and consequently small businesses help to diversify the economy and at the same time create employment (Machacha, 2002, Banda et al, 2004). Therefore, the ability for SMEs to survive in an increasingly competitive global environment is largely dependent upon their capacity to leverage technologies. Conclusion and Recommendations The use of ICT can provide a platform for future growth of SMEs however; the use of ICT in Nigerian SMEs is relatively low due to many factors militating against their growth. For Nigerian SMEs to effectively use ICT, technological infrastrucures should be put in place by the government to support ICT use. Based on the literature review and case study, it is certain that there are several benefits associated with the use of ICT. Hence, effective use of ICT in Nigeria SMEs would bring about enormous opportunities for these SMEs. Therefore, for an SME to set itself apart from its competitors and also have a sustainable competitive advantage there is a need to invest in ICT. There is also a need for the government to intensify the efforts of promoting the use of ICT in Nigerian SMEs since ICT is known to improve managerial practices in SMEs and also assist SMEs to grow and become more innovative. Finally, the Nigerian government must invest largely in the SME sector by making more funds available to SMEs and putting structures in place to ensure a successful investment. The integration of ICT in Nigerian SMEs would help integrate these SMEs into the world IT village.

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

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