Investigating the effect of pH on the activity of phosphatase enzymes

My aim in this experiment is to see how well an enzyme (phosphatase in this case) reacts under a controlled temperature but a varying pH. Enzymes are known to be effected by pH and temperature. Both of these change how quickly the enzyme can process a substrate, so perfect matches must be found for each enzyme. At a low temperature, the enzymes reaction is so slow that any product is hardly noticeable. At a high temperature, or an extreme pH, the active site of the enzyme is damaged, so the substrate cannot be processed. I predict that the optimal pH for the reaction to take place will be more acidic when the temperature is set at 25o c and the length of incubation is 10 minutes. A suitable pH would be between 3 – 5oc. I conducted preliminary experiments and chose to incubate at 25o c instead of the higher temperatures for the simple reason that I knew that at a higher temperature (around 35o c), the reaction would go at its fastest, and I ran the risk of high magenta values (I wanted to keep them all under 1 so they could be easily compared). I therefore wanted to see what would happen at lower than 35o c as far as reactions were concerned, so I chose 25o c. My method was adapted from a worksheet on varying the temperature in the same reaction, keeping pH constant. 1. Label a microfuge tube with your initials. 2. Place two mung beans into the labeled tube. 3. Add 0.5ml distilled water into the tube containing the beans. 4. Crush and macerate the beans with a small glass/plastic rod. 5. Take a second microfuge tube and add water to the same level as the one containing the mung beans. (TO BALANCE THE CENTRIFUGE RACK) 6. Place the tubes into opposite holes of the centrifuge rack and spin for 5 minutes at maximum speed 7. After spinning, draw off as much of the clear supernatant above the pellet as possible and place into a clean microfuge tube. This solution now contains the enzymes for the experiment. 8. Using a graduated pipettor, add 100?l of sodium carbonate (the buffer solution in this experiment). 9. Then add 20?l PPP substrate to each of the eight microfuge tubes. Wash the pippettor thoroughly. 10. Finally, add 20?l enzyme solution into it. 11. Repeat steps 8 through 10 as quickly as possible, to collect all the microfuge tubes. Now insert them into a Styrofoam float and place this on the surface of the water bath for 10 minutes, timed with a stop clock. 12. Now add 100?l Sodium Carbonate to stop the reactions. 13. Estimate the colour of the magenta using the magenta filters provided. The possible variables in this method are the volumes of substrate, enzyme and sodium carbonate along with the time in the water bath and the temperature of the water bath. The volumes will be measured as closely as possible with a micropippettor. Results: The number in the test tube column is the magenta filter that corresponded to the colour of the completed reaction. The higher numbers mean more reaction, lower means less reaction. Every time that I added the sodium carbonate to cancel the reaction, the colour change to magenta was sudden and with a small amount of shaking, the whole liquid was tinted purple. I managed to take 2 readings for each pH, and therefore average them. Without doing the preliminary experiment, I would have never known what temperature to try. This graph shows clearly how good my results were. They fit with my prediction that the optimum pH for a Phosphate enzyme is around pH 3-5, and therefore we can say that it requires a more acidic pH than an alkaline one. My conclusion, using this graph as evidence, is that a Phosphate enzyme works at its maximum speed at a lower pH, in this experiment pH 4, taking into account the other variables in the experiment. For instance, at a different water temperature, the pH required may vary. As mentioned before, as the temperature raises, so does the probability of denaturation. From the results, I assume this is beginning to happen before pH 5. But these results are not precise. I have no way of knowing which side of pH 4 the reaction is faster, i.e. if pH 3.9 is faster than pH 4, or pH 4.1. The pH4 that I got as being the fastest speed may not be the pinnacle of the reaction curve. Huge accuracy errors could have been made, for instance: * Was the precise equal amount of liquid put in each of the tubes? Probably not, the micropipette was hard to use and had very small scales. * Some reactions began before others when preparing to put the microfuge tubes into the water bath. You had to work incredibly quickly to prepare all of the tubes in as fast a time as possible. However, seeing how precise my results were, either I made the same mistakes over and over, therefore giving a whole set of incorrect results, or I did them all very well. This is the risk in using this method. If I were to change the method, I would get far more precise pipettes and find a way of adding the enzyme into the solution as quickly as possible, like getting 8 micropipettes filled and ready, then using one for each microfuge tube in quick succession. If this experiment was to be taken further, I would get people to work together and double check their accuracy as they go, so that they can do the final step before incubation in half the time or less. Instead of changing the pH, they could change the variable concerning the temperature of the water bath to be incubated in. Another possibility is that the different volumes could be changed to see how the results vary, of course only one at a time. For example, change the amount of enzyme to be put into the mixture, continue the experiment with other set variables and see what type of results you get.

Sexism in Sherlock Holmes

Sexism can be identified as being prejudice towards someone or for stereotyping or discriminating them, on the basis of gender. However, Sherlock Holmes is not sexist within the book, dramatization and modernized episode. In the novel, â€Å"A Scandal in Bohemia† by Conan Doyle, the protagonist Sherlock Holmes is not portrayed to be a sexist character. To begin with, Sherlock insists on having Doctor John Watson remain alongside with him. Just before the King of Bohemia enters for his consultation with Sherlock Holmes regarding his case, Watson offers to leave but Sherlock responds by saying, â€Å"[n]ot a bit, Doctor. Stay where you are. I am lost without my Boswell†¦ it would be a pity to miss it. † (5). Sherlock invites Doctor Watson to stay in the room before the King of Bohemia comes in. This shows that Sherlock cares for having his friend and colleague in the room when he is working. Sherlock is not discriminating against the male sex because Doctor Watson is a male figure and Sherlock wants him to stay so that way he can record any details and understand all that is going on and afterwards help him with their case. Furthermore, Sherlock Holmes addresses Irene Adler in a respectful manner. After the great scandal that threatened the Kingdom of Bohemia is resolved, Doctor Watson says Sherlock, â€Å"[w]hen he speaks of Irene Adler, or when he refers to her photograph, it is always under the honorable title of the woman. † (13). Whenever Sherlock is speaking of Irene Adler he uses the term ‘the woman’, which is not used as a demeaning term. Instead it is a title that Sherlock’s uses to show his respect for Irene. Since Sherlock has respect for Irene it illustrates that he is not sexist against women. Therefore, Sherlock Holmes is not sexist because he insists of having Doctor Watson remain alongside with him and addresses Irene in a respectful manner. Within the dramatization â€Å"A Scandal in Bohemia† directed by Paul Annett, again Sherlock Holmes is also not depicted as a sexist character. Firstly, Sherlock Holmes is attracted to someone of the opposite sex. When Sherlock Holmes said â€Å"Irene Adler had a face that any man would die for†, he preferred to take her photograph to a rich ring from the King of Bohemia’s finger. Sherlock clearly finds Irene Adler to be beautiful and would much rather keep her picture then the King’s ring. Sherlock is very attracted to Irene since she outwitted him. He thinks highly of Irene as opposed to being sexist against her. Moreover, Sherlock supports the marriage between a male and a female. When Irene and Norton are about to get married, they need a witness for their marriage to be legalized. Therefore Sherlock who is in disguise witnesses the marriage between the two. The fact that Sherlock is there to witness their marriage shows that he indeed supports the wedding between the two. He is not displaying any sexism towards either males or females in this example, because he is not discriminating against them or favoring one gender over the other. For these reasons, Sherlock is not sexist in the dramatization because he is attracted to someone of the opposite sex and he supports a marriage between both a male and female. Lastly the modernized episode from the television show â€Å"Sherlock† is based upon on â€Å"The Scandal in Belgravia†. Here Sherlock Holmes is not represented to be a sexist character. Firstly, Sherlock Holmes puts his own life in danger to protect a woman. When the American CIA’s harmed Mrs. Hudson, Sherlock became angry and killed all of them. This shows that Sherlock cares for Mrs. Hudson. Although the CIA’s were well equipped with guns that could easily harm them all, Sherlock was determined to save Mrs. Hudson. Since Sherlock put his own life at risk to protect Mrs. Hudson’s, it shows that he is not sexist against women, especially when he saved the life of one. In addition, Sherlock Holmes saves the life of another female. At the end of the episode when the Karachi terrorist group were about to chop off Irene’s head, Sherlock rescues her. Sherlock helps Irene escape when she was on the brink of death. If Sherlock was sexist, then he would have let Irene die. However, he cannot let anyone be cruel to her which demonstrates that he is not sexist against females. Therefore, Sherlock Holmes is not sexist in the modernized episode because he saves the lives of two women. All in all, I believe that Sherlock Holmes is not represented as a sexist character in the book, dramatization and If only one dramatization between the two that we watched in class were to survive, I would choose the dramatization of the episode â€Å"A Scandal in Belgravia† from the television series â€Å"Sherlock†. I would choose this version because it is a modern version based on the book. As time has pass, it is difficult for people to follow along and understand the English language that has been spoken in the past. Thus it will be easier for the future generation to understand this version because the language is English from the twenty first century, as opposed to the other dramatization which was made in twentieth century. Also, this dramatization expands on the storyline. There are a lot more scenes added such as the hiker dying with the boomerang in the beginning or Irene Adler almost being killed at the end. These scenes make the episode more action packed and intriguing to watch. Also, this dramatization introduces more advanced technology such as the camera phone, internet blogs, modern firearms and a science laboratory that holds advanced equipment. Not only that but more characters are introduced such as Sherlock’s Holmes brother, Moycroft, the CIA group and Moriarty, who all make the episode very entertaining! In addition, it has more appealing genres then just mystery, there is action, romance, and comedy. Furthermore, the entire cast for the television series has wonderful acting skills. Its two stars, Benedict Cumberbatch, who plays Sherlock Holmes, and Martin Freeman, who plays Doctor Watson, they have such amazing chemistry. They make the episode livelier and humorous to watch. Therefore, I believe that the modernized dramatization should survive because it is easier to follow along through the vocabulary, it expands on the plot and has an amazing selection of wonderful actors and actresses.

Advantages of Skilled Worker Migration

Advantages of Skilled Worker Migration Doctors Without Borders â€Å"Doctors Without Borders†, written by Charles Kenny, discusses the advantages of allowing skilled workers to migrate from a â€Å"poor† state into a â€Å"rich† state and vice versa. Kenny also states that when medical doctors are allowed to migrate and work in other states it can cause all of the states involved to benifit. His main point in this article is that allowing skilled workers to migrate would boost the global economy and lower poverty rate in lower class states where the individual migrant workers migrated from. Kenny uses key facts regarding migrant workers total income to strengthen his argument. He states that between 1985 and 2005, the amount of foreign high income citizens in a state has jumped to nearly 10 percent. Kenny says â€Å"That’s great news for the rich states that benefit from their skills, of course. But as it turns out, it is also great news for the poor countries the migrants leave behind† . Kenny states that every immigrant on average sends approximately six thousand dollars in remittance per year to their home country. Also when migrant workers immigrate, they increase the trade between the two states by ten percent (Kenny 2). With this remittance, migrant workers can cut down poverty by nearly one third percent in low class countries (Kenny 2). Another fact that Kenny uses to prove his point is the booming IT industry in India. Kenny says that because so much information about technology was transmitted back to India in the 1990’s it has caused over 2.5 million people to be hired for IT work. The final point that Charles Kenny uses in his article is that the United States is moving in the opposite direction regarding this topic. Kenny’s opinion toward the United States and its idea about this article is this, â€Å"It is hard to find a more confused discussion than that surrounding ‘brain drain’. Opposition to unskilled migration is usua lly based on perceived self-interest, the threat of stolen jobs — a misguided fear, but at least a rational one.† Kenny says And at the other end of the degree process, there is growing concern about a â€Å"reverse brain drain,† as more foreign graduates from U.S. schools decide to return home rather than find jobs in America — again, often on account of byzantine immigration rules. Meanwhile, the U.S. House Appropriations Committee has proposed deep cuts to State Department international exchange program budgets that support the Fulbright program, among others. This shortsightedness regarding a program that promotes the talent trade in both directions isn’t just bad news for the development prospects in Africa or Asia; it’s likely to convert into a further erosion of America’s long-term productivity. The idea of doctors without borders has also affected the international system and its main actors tremendously. It has caused an incre asing number of politicians to being favoring immigration and bringing attention to the gains an individual state in the international system can create for itself on the individual scale within the state. For individual states in the international system, this topic draws much interest. Nearly every state in today’s global economy would like to strengthen themselves economically. With the increase of knowledgeable, skilled, migrant workers, individual states citizens will have more inspiration to acquire higher paying jobs. Kenny says that this is possible due to the amount of remittance sent back to a migrant’s home state. â€Å"If the amount of remittance sent to a migrant’s home state was doubled, it would lower the poverty rate and begin to balance the national economy. The amount of money sent back to home countries would triple the amount of foreign aid sent in the past year. This topic also effects individual global state on a more national level. As a growing number of educated immigrant workers enter into a country, non-governmental organizations will be strengthened. Fields of study like healthcare and technology would be improved drastically. For example intergovernmental organizations regarding workers of a skilled background can be strengthened by the increase of skilled migrant workers. In the global scale, the admittance of migrant workers into states needing skilled labor can benefit not just the country with the migrant worker, but the whole global community. On a lower scale, organizations located inside a state can be boosted also. With the increase of skilled migrants, organizations like IDCI’s, NDGO, SCOS, and many other non-governmental organizations can benefit by the increase of foreign workers.

Home Schooling Essay Example | Topics and Well Written Essays - 1000 words

Home Schooling - Essay Example Looking at the nature of homeschooling it can be noticed that it seriously needs regulation. The regulation comes with challenges. The regulation of homeschooling has over the years had various critics criticizing its necessity. As much as there are various points that successfully explain the lack of necessity for homeschooling, there are arguments with bigger intensity explaining the need for regulating homeschooling. The arguments mainly proves the necessity of regulation of homeschooling to ensure its productivity. Discussion One reason why home schooling should be regulated is because of the high rate at which its rising and the high possibility of it being abused. Some parents might take advantage of homeschooling to serve their own interests. This is a possibility in cases where parents are trying to hide some aspects of their current or past lives. For instance, violent parents might take advantage of homeschooling to hide the inhuman things that they do to their children. Th is way they will be able to hide the bruises that result from the mistreatment that they subject their children to. This will create a scenario where the children will be having their basic rights violated, but no one will come to their rescue because no one knows. This can also be used by parents with criminal records to serve their own interest (Kunzman, 2009). However, it is clearly evident that this can have very minimal effect on the overall effectiveness of the productivity of homeschooling. Homeschooling should also be regulated because of the quality of education that all individuals are entitled to. Researches have it that, without proper regulation, the quality of education given to homeschooling students can easily be compromised. As much as there is always a fixed curriculum to be followed by both homeschool and public school teachers, it is hard to tell whether the homeschool teachers effectively cover the curriculum. This will mean that, in the end, the students would not have attained the intellectual maturity that is expected of a student that has gone through the United States of America’s education system (McMullen, 2002). The ultimate result of this sub quality education is that the students will not be able to keep up with the students going through the standard type of education both at higher levels of education and in various professions. Students who have gone through homeschooling through their high school years are less expected to major in the natural sciences than the non-homeschooled students, and that more attention has to go to this because of the growing number of homeschooled students in the United States of America. Homeschooled students are not exposed to professional science teachers and labs and so do not have as many options, with their growing number this could be a threat the education system (Phillips, 2010). This will definitely call for regulation because the increase in the number of people being homeschooled will, therefore, mean that there is a significant decrease in the number of professionals in natural science, a factor that might affect the country economically, politically and socially. Taking a look at the motives that parents usually have when

Law of Torts Case Study Example | Topics and Well Written Essays - 2500 words

Law of Torts - Case Study Example The inherent ambiguity as to what conduct will constitute an interference with the use and enjoyment of land in order to justify an action in private nuisance has facilitated the piecemeal development of legal principles in this area2. This is further evidenced in context of environmental litigation3. Moreover, it has been widely extrapolated the law of nuisance is the most significant course of action in respect of environmental disputes4. However, commentators have criticised the multifarious limitations in private nuisance claims, which further render inherently complex cases difficult to be brought to court with any realistic prospect of success5. Indeed, the very nature of a claim being available only when environmental damage directly affects the use and enjoyment of another person's land intrinsically limits the parameters of nuisance6. Furthermore, the decision in the case of Hunter v Canary Wharf7 renders private nuisance claims dependant upon demonstration of a proprietary interest in the land, which has fuelled academic debate regarding the decision's implications for private nuisance claims8. The focus of this analysis is to evaluate the implications of the decision in the Hunter case, particularly in context of the development and application of the strict liability rule in Rylands v Fletcher9. Firstly it has been submitted that the arbitrary nature of judicial developments in private nuisance claims would alternatively be better addressed by the strict liability rule as established in Rylands v Fletcher10. The Rylands rule relates to the situation where a non-natural land user keeping something on their land, which is likely to escape, and as such, is stated to be kept at their own peril11. If the "thing" does escape, the rule affirms that the individual will be liable for all damage that is a natural consequence of the escape12. In the Rylands case itself, the defendant was a mill owner who had employed an independent contractor to build a reservoir on his land. The contractor had been negligent in failing to block a disused mine shaft that he had come across on the site. As a result, when the reservoir was filled, water escaped causing damage. As the contractor was independent the landowner was not liable for negligence or vicariously liable for the contractor's conduct13. In delivering the judgement for the claimant, Blackburn J asserted "the rule only applied to a thing which was not naturally there14". Furthermore, Lord Cairns presiding in the House of Lords additionally qualified the applicability of the Rylands rule to where the defendant had actually brought the thing onto his land15. The rule was further developed in the decision in Reads v Lyons16 by determining that one cannot claim for personal injuries in private nuisance but only for the discomfort caused to the use of the land itself17. The essence of the rule is that it is a form of strict liability for the escape of 'things' likely to cause damage and which have been brought onto land18. On the one hand the strict liability rule in Rylands leans towards legal certainty in this complex area of law by

Is addiction a disease or not Essay Example | Topics and Well Written Essays - 1250 words

Is addiction a disease or not - Essay Example 1). Saah, on the other hand, provided the meaning of the term as â€Å"a personality disorder, (which) may also be seen as a worldwide epidemic with evolutionary genetic, physiological, and environmental influences controlling this behavior† (Saah: Introduction par. 1). The National Institute of Drug Abuse (NIDA) presented its meaning as â€Å"a chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences† (NIDA par. 1). These definitions have disparities in terms of identifying addiction as a state of dependence, which is a behavioral or personality condition; as contrasted to it being identified as a disease of the brain. The aim of the current discourse is to determine whether addiction is a disease or just an extreme form of learning. Background and Review of Literature The history of having diagnosed addiction as an abnormal condition was noted to have originated from the 1800s where doctors allegedly worke d with patients, identified to have been diagnosed with alcoholism and drug addiction, as confined in private sanitariums (Origins Recovery Centers). Only in 1934 was it disclosed that a particular doctor, Dr. William D. Silkworth, had apparently revolutionized finding appropriate and effective treatment for addiction through the establishment and close link of working and being supported by a group of committed individuals. As noted, â€Å"it was the doctor’s belief that an addict has both mental and physical abnormalities† (Origins Recovery Centers par. 5). At this stage, addiction has already been identified complex in terms of containing mental, as well as physical abnormalities; components which were separately identified in definitions noted above. From the study written by Sussman and Sussman, the authors explored the various definitions of addiction. Accordingly, the authors included â€Å"elements of addiction derived from a literature search that uncovered 5 2 studies include: (a) engagement in the behavior to achieve appetitive effects, (b) preoccupation with the behavior, (c) temporary satiation, (d) loss of control, and (e) suffering negative consequences† (Sussman and Sussman 4025). The authors have likewise uncovered the date of origin of examining addiction cases to the 1700s from the study written by Meyer entitled â€Å"The disease called addiction: Emerging evidence in a 200-year debate† (Sussman and Sussman 4036). On the contrary, addiction was emphasized that it was not at all a disease but instead, an extreme form of learning. Lewis contended that other emotions, such as love, also alter the brain; yet, not called a disease. He argued that â€Å"physical changes in the brain are its only way to learn, to remember, and to develop. But we wouldn’t want to call learning a disease† (Lewis par. 9). To this, he aptly concluded that â€Å"addiction (whether to drugs, food, gambling, or whatever) doesnâ⠂¬â„¢t fit a specific physiological category. Rather, I see addiction as an extreme form of normality, if one can say such a thing. Perhaps more precisely: an extreme form of learning. No doubt addiction is a frightening, often horrible, state to endure, whether in oneself or in one’s loved ones. But that doesn’t make it a disease† (Lewis par. 11). Analysis of the Definition of Addiction and Confirmation From the definitions that were provided, one affirmed that these

Digital Age, Electronic Identity and Nature of Relationships Essay

Digital Age, Electronic Identity and Nature of Relationships - Essay Example Vie makes it clear that every time people upload their photos or participate in any form of communication in the social networking sites, they create an identity for themselves, which their friends at the site will identify them with when they analyze their information. It is not only social networking site that create an electronic identity, but any form of online transaction that requires people to enter their personal information like buying products online (Vie, 17). These transactions leave a trace of information that other internet users will use to identify people. Many of the electronic identities are created unconsciously, but they leave traces of people electronic identity and can be used to refer to them by others. She gives an example of the identities created in the Gmail account, where the system will bring adverts on the right side of the screen based on the information people view in the account. People’s electronic identity can portray information about people that others may use to judge them, which can lead to loss of identity and denial of a private life. However, the electronic identity will help in formation of relationships and connect with people known in the past lives. I agree with Vie’s assertion that the digital age has altered our understandings among social relationships and ourselves. In the digital age, social media have had the most crucial role in the understanding of the relationships people form since it has become part of everybody’s lives. Organizations have also joined in the social media to conduct their operations hence sites like Facebook and twitter just to name a few have become frequently used for communication. People are required to form profiles from which they will post information concerning themselves for others to use. Communication has been made easy since people can communicate globally and meet new people (Harris). From the profiles people create in the social networking sites, they pos t their thoughts on them, and people will communicate back by writing comments. The digital age has helped people to get new friends easily and connect with people they may have lost contacts within the past. For this reason, the digital age has formed an easy way for people to meet and share ideas on different issues in the society and their lives. Vie explains that people need to put a balance on the between the need to meet with people and their personal privacy. She explains that the electronic identity created in the social networking site can be of help and at the same time tamper with privacy of people’s information. This is because the information people post on the sites can be used in the later stages of life to deny people opportunities. Conversations with friends are open for people to see and may be disastrous if not used in the right manner. The American culture is one that people will judge others from the experiences, and it may happen that one can post some s ensitive information on the sites that may be used against them in the future. For example, in job seeking, there have been some reports that employers will look at the potential employees social media profiles, and if there is some compromising information, they may not be employed. For this reason,

The Dividend Received Deduction Term Paper Example | Topics and Well Written Essays - 1250 words

The Dividend Received Deduction - Term Paper Example This paper broadly explores the concept of dividends received deduction. Dividend moves from one company to another before it reaches an individual taxpayer, who happens to be a shareholder in the receiving company. For example, if there are two corporations, A and B in such a way that B has shares in A then the dividend will be taxed twice before it reaches the final shareholder, who also will be taxed. This means there will be two 35% taxation at the corporate level and one 23.8% at an individual taxpayer level hence making the real tax to be nearly 68%. This would even be worse when the dividend has to move a long a series of corporations before it reaches the final stockholder. For example, a situation where company A pays dividend to company B who then pays to C that in turn pays them to the individual shareholders. Following the above stated reasons, pertaining to double taxation, dividends are not taxable thrice or more. As a result, dividends received by a company will be 70% tax-free. Rumpf (2011) asserts that this condition holds unless the corporation in question faces disqualification from this privilege due to some reasons. Even so, when deciding an individual’s dividend income, it is essential to comprehend or, rather, take into account the relationship between dividend and other taxable partaking such as straddles and constructive sales. The history of dividends received deduction is completely different from that of certain income of tax-exempt corporations. Revenue Ruling 104, 1953-1 C.B. 68 fully explores the policy. According to this ruling, the belief that a corporate tax is paid prior to earnings from which the dividends are distributed supports the credit for dividends earned. In other words, a corporate tax had been paid on the proceeds that give rise to dividends ahead of the distribution. According to Rakshit and Sarkar (2013), this

The CEO's Private Investigation Essay Example | Topics and Well Written Essays - 1250 words

The CEO's Private Investigation - Essay Example Cheryl was coming into the company from their rival Boeing and she had heard some rumors while at Boeing about their being some shady dealings while the previous CEO, Jim Rawlings had been in office.   Based on the rumors, Cheryl began to ask her assistant if she knew of anything that has transpired before she came on board.   The assistant was hesitant at first but finally, let Cheryl know that she had suspicions about a file that Mr. Rawlings did not let her file for him.   She was surprised because he had not done this before and trusted her with all of his files except for this one. Cheryl felt as if this was enough to go on and she wanted to find out if there truly was something shady going on within the company. She went to her rival for the job first and asked him some questions but he did not admit nor deny anything. He indicated that it would be a lot of trouble to find out and maybe she should let it go. Cheryl was not satisfied with this response and went to speak wi th the general counsel of the company. The general counsel basically told her that if she did pursue it and there was nothing to pursue she would look bad. He also said that if she did not pursue it and something was wrong she would look bad. The only way she would look good was if she pursued the issue and there was actually something to find. But the way that she even thought something was going on was based on rumors. The issue here is whether or not Cheryl Todd should pursue the rumor that something might have been shady within the company. On the one hand, she is going on a rumor and not fact. She herself is not privy to any information that would suggest something is or was going on while Jim Rawlings was the CEO. Hank Bodine, her rival for the position, indicated that if she pursued this, she would come across as someone that would be trying to sabotage the company from within. Although this is not Cheryl’s intentions, she would have a hard time proving that she was no t trying to jeopardize the company or Jim Rawlings’ name if she launched an investigation and nothing came of it.

Mini project Essay Example | Topics and Well Written Essays - 1000 words

Mini project - Essay Example This advert has been used to inform the customers that Samsung handsets are available and that have equally better applications and features like any other latest models or even better. The display on the advert shows the Samsung hand set has more superior and modern with appealing look. This type of advertising is employed mainly for introducing a new product or service in the market. It can also be used to boost the popularity of an already existing product in the market. The consumers have to know that a certain product or service exists before they can go for it. This advertising therefore aims at creating a demand for the products and services and by extension sensitizing potential customers (Amaldoss & He, pg. 147). . A well informed customer derives satisfaction and is therefore motivated to buy a product or subscribe to a service the next time. It is through this that loyalty is created and customers are maintained. Considering the benefits of this form of advertising, it should therefore be considered an indispensable method of marketing that any business firm should embrace. Moreover, informative advertising should be made in a simple and comprehensive language that favors most customers if not all. This type of advertising is employed mainly for introducing a new product or service in the market. It can also be used to boost the popularity of an already existing product in the market. The consumers have to know that a certain product or service exists before they can go for it. This advertising therefore aims at creating a demand for the products and services and by extension sensitizing potential customers (Amaldoss & He, pg 147). More often than not customers have certain concerns about products available in the market, this can be in regard to their advantages and demerits as well as how to use these products. Very sensitive elements of a product such as prices, areas of use and why a customer needs to buy that particular product are also

Goffmans Dramaturgical Sociology Essay Example for Free

Goffmans Dramaturgical Sociology Essay The article by Brown elaborates on traditional symbolic interactionism. Goffman was mainly interested in social self in the society that constitutes of individual personality formation. His notion of self involves engaging in purposive forms of activities and impressions. According to Goffman’s dramaturgy, there are various schools of interactionist analysis. People try to manipulate themselves and the situations in which they interact. Goffman’s interests were more to the ritualized forms of social interaction. There are various wings of interactionism; we have the social psychological, social of construction and social ritual wing. The difference in these wings allows one to create bridges between elements of symbolic interactionism and other types of social theory (Brown, 290). The article states that in order to teach Goffman well, instructors should put emphasis on social rituals, symbols and sacred representations so as to produce emotional attachment that enhances solidarity in groups among students. Students will be encouraged to see the difference in strands of symbolic interactionism, conflict theory, classical and contemporary theory. This will result to students’ capabilities being increased and they will maintain themselves creative synthesis. Students should know that the facts of symbolic interactionist are just fictions. However, they carry conspicuous effects of social life. In macro-sociology, Goffman observes given situation as a reality that is on an equal footing with human preference (Brown, 294). This is unlike other traditional interactionists. Additionally, Goffman uses the concept of frames to show the incomparability of situations in everyday life. These frames include elements of symbolic meaning, social roles, norms and hierarchies of power that represents participants’ behaviors. Finally, Goffman puts into considerations disruptions, ambiguities, and reparations of social routine as part of everyday life. They are called breaking frames and they cause an embarrassment in life situations. Work cited Brown, David. Goffman’s Dramaturgical Sociology: Developing a Meaningful Theoretical Context and Exercise Involving ‘ Embarrassment and social organization’. American Sociological Association, 2003, pp. 288-299

Violence enforcement of City Urban Management officers Essay Example for Free

Violence enforcement of City Urban Management officers Essay City Urban Management Enforcement Bureau is a local government agency in mainland China that is in charge of maintaining the order of daily business activities of markets and streets in cities. This Bureau was established to deal with the increasing problems when China is in the process of rapid urbanization in these years. However, it’s notorious for abusing power and violent enforcement. Reported by Feng(2008), â€Å"on January 7, a man was beaten to death by a group of city administrators for filming their violent enforcement of an expired contract in Wanba Village in central Chinas Tianmen City, Hubei Province†( ¶ 1). This kind of conflict occasionally happens everywhere in mainland china in these years for more and more rural people come to cities to find more jobs and opportunities. The City Urban Management Enforcement Bureau which is set up to handle cases with vendors and the environment of cities now becomes a violator of human right. As mentioned in â€Å"Killing sparks protests in China†(2008) â€Å"This para-police force, equipped with steel helmets and stab-proof vests, is often used by local officials as trouble-shooters†( ¶ 13). How can law enforcement professionals become lawbreakers? The investigation combining with the living experience in mainland China shows that the three common causes for this problem are are poor communication, profit driven and lack of regulations. These have led to the bad behavior of those officers. The first cause of violence enforcement is the poor communication because of low education level. The officers are responsible for cracking done on no-license vendors and tackle with some low-level criminals so that they mainly deal with the low-income group of people who are mainly formed by the rural migrant workers or villagers in a city. Those people usually don’t have a very high education level. According to the 2009 migrant workers monitoring survey report (2009), over 75% migrant workers only have junior high school education or below(n.p.). While the communication skills and education level of the officers are also low. From the report of Ramzy  (2009), â€Å"officers were often drawn from the ranks of laid-off workers from state-owned enterprises and given little training in law enforcement†( ¶ 10). So the only way they can complete their mission is to treat the vendors violently to warn them not to break the rules again. Both sides in this conflict have difficulties to understand each other and when either of them is irritable and impulsive, violent confrontations may happen. The second cause of abusing of power and violence enforcement is the officers can earn profit from punish those poor guys, which drive them beat defenseless people on the street and take all they have without any mercy or sympathy. Li (2006) observed that â€Å"those peddlers who are a little slow often suffer, as the law enforcers snatch away their merchandise, tools and handcarts. The peddlers are made to pay fines, which the law enforcers have the right to levy for a series of misdemeanors† ( ¶ 8). For the people who are too poor to afford the fines, the officer some time ruin the handcarts and tools of the vendors and divide misdemeanors with their colleagues. It is more or less similar to the triad threatening for protection fees on the street. This profit drives the officer in chasing the vendors and use violence to force them to surrender without any respect to human right. The senior level of the government is also responsible for such violate events because they indulge their staff and do not come up with any strict regulations to restrict their behaviors. Though those two causes mentioned above truly have effect on the behavior of the Urban Management Officers, the third one is the most obvious and serious cause of abusing of power and violence enforcement. Some indirect evidences show that some of the violate enforcement events even happens with the acquiescence of the senior government. A common situation is that the leaders of the Bureau only want their officers to clean out all the vendors on the street no matter what they do to achieve it. Just like Ramzy said (2009), â€Å"Its precisely because the Chinese bureaucracys idea of an ideal city doesnt include peddlers and street vendors that the [urban management officers] developed into such a powerful institution† ( ¶ 8). And when the violence enforcement event is exposed, they are always shifting the responsibility to their staff or some one else and do not consider their responsibility of regulation. The events  of abusing of power and violence enforcement will continue happening unless the local government set up strict regulations and punish the officers who break the law. The abusing of power and violent enforcement of urban management officers is a tough problem with several causes and complex background, but it is not impossible to solve as long as the government takes effective actions such as providing necessary training to the officers and restricting their behavior. Though the vendors or villagers break the law first, it can not be the reason to abuse someone and violate his human right. Every one participating in dealing with such troubles should remember that consideration and respect are the best solutions but not violation and conflict. Reference: Killing sparks protests in China. (2008 January 9). BBC News. Retrieved 29 September 29, 2011 from World Wide Web: http://news.bbc.co.uk/2/hi/asia-pacific/7178382.stm Feng Yiran. (January 12, 2008). Man Beaten to Death for Filming City Administrators Brutality. The Epoch Times. Retrieved 29 September 29, 2011 from World Wide Web: http://en.epochtimes.com/news/8-1-12/63964.html Austin Ramzy. (May 21, 2009). Above the Law? Chinas Bully Law-Enforcement Officers. Time magazine. Retrieved 29 September 29, 2011 from World Wide Web: http://www.time.com/time/world/article/0,8599,1899773,00.html Li Xing. (17 August 2006). Services must be improved for better law enforcement. China Daily. Retrieved 29 September 29, 2011 from World Wide Web: http://www.chinadaily.com.cn/opinion/2006-08/17/content_666765.htm Guo Shipeng and Benjamin Kang Lim. (April 10, 2007). Chinese sausage seller spared execution. Sign on San Diego. Retrieved 29 September 29, 2011 from World Wide Web: http://legacy.signonsandiego.com/news/world/20070410-0229-china-crime-.html

Radio Resource Management in OFDMA Networks

Radio Resource Management in OFDMA Networks 1 Introduction The convenience and popularity of wireless technology has now extended into multimedia communications, where it poses a unique challenge for transmitting high rate voice, image, and data signals simultaneously, synchronously, and virtually error-free. That challenge is currently being met through Orthogonal Frequency Division Multiplexing (OFDM), an interface protocol that divides incoming data streams into sub-streams with overlapping frequencies that can then be transmitted in parallel over orthogonal subcarriers [2,3]. To allow multiple accesses in OFDM , Orthogonal Frequency Division Multiple Access (OFDMA) was introduced. Relaying techniques, along with OFDMA, are used to achieve high data rate and high spectral efficiency. 1.1 Orthogonal Frequency Division Multiple Access OFDMA, an interface protocol combining features of OFDM and frequency division multiple access (FDMA)., was developed to move OFDM technology from a fixed-access wireless system to a true cellular system with mobility with same underlying technology, but more flexibility was defined in the operation of the system [1,8]. In OFDMA, subcarriers are grouped into larger units, referred to as sub-channels, and these sub-channels are further grouped into bursts which can be allocated to wireless users [4]. 1.2 Relay-Enhanced Networks In cellular systems, a way to achieve remarkable increase in data rate, but without claiming for more bandwidth, is to shrink cell sizes, however, with smaller cells more base stations (BSs) are needed to cover a same area due to which deployment and networking of new BSs acquire significant costs [5]. An alternative solution to this problem is to deploy smart relay stations (RSs), which can communication with each other and with BSs through wireless connections reducing systems cost. A relay station (RS), also called repeater or multi-hop station, is a radio system that helps to improve coverage and capacity of a base station (BS) and the resulting networks employing relay stations are sometimes called cooperative networks [6]. 1.3 Technological Requirement The continuously evolving wireless multimedia services push the telecommunication industries to set a very high data rate requirement for next generation mobile communication systems. As spectrum resource becomes very scarce and expensive, how to utilize this resource wisely to fulfil high quality user experiences is a very challenging research topic. Orthogonal frequency-division multiple access (OFDMA)-based RRM schemes together with relaying techniques allocate different portions of radio resources to different users in both the frequency and time domains and offers a promising technology for providing ubiquitous high-data-rate coverage with comparatively low cost than deploying multiple base stations [5]. Although wireless services are the demand of future due to their mobility and low cost infrastructure but along with this they suffer serious channel impairments. In particular, the channel suffers from frequency selective fading and distance dependent fading (i.e., large-scale fading) [1, 8]. While frequency selective fading results in inter-symbol-interference (ISI), large-scale fading attenuates the transmitted signal below a level at which it can be correctly decoded. Orthogonal Frequency-Division Multiple Access (OFDMA) relay-enhanced cellular network, the integration of multi-hop relaying with OFDMA infrastructure, has become one of the most promising solutions for next-generation wireless communications. 1.3.1 Frequency Selective Fading In wireless communications, the transmitted signal is typically reaching the receiver through multiple propagation paths (reflections from buildings, etc.), each having a different relative delay and amplitude. This is called multipath propagation and causes different parts of the transmitted signal spectrum to be attenuated differently, which is known as frequency-selective fading. In addition to this, due to the mobility of transmitter and/or receiver or some other time-varying characteristics of the transmission environment, the principal characteristics of the wireless channel change in time which results in time-varying fading of the received signal [9]. 1.3.2 Large Scale Fading Large scale fading is explained by the gradual loss of received signal power (since it propagates in all directions) with transmitter-receiver (T-R) separation distance. These phenomenonss cause attenuation in the signal and decrease in its power. To overcome this we use diversity and multi-hop relaying. 1.3.3 Diversity Diversity refers to a method for improving the reliability of a message signal by using two or morecommunication channelswith different characteristics. Diversity plays an important role in combatingfadingandco-channel interferenceand avoidingerror bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver [10]. 1.4 Proposed Simulation Model We developed a simulation model in which each user-pair is allocated dynamically a pair of relay and subcarrier in order to maximize its achievable sum-rate while satisfying the minimum rate requirement. The algorithm and the results of the simulation model are given in chapter 4. 1.5 Objectives The objective of our project is to have a detail overview of the literature regarding Orthogonal Frequency Division Multiple Access (OFDMA), Radio Resource Management (RRM) and Relaying techniques. After literature review we developed a simulation framework in which we will try to use minimum resources to get maximum throughput by using dynamic resource allocation. 1.6 Tools For the design and implementation of proposed Algorithm, we have used the following tools MATLAB Smart Draw Corel Draw 1.7 Overview Chapter 2 contains the literature review. It explains the basic principles of OFDMA, Radio Resource Management (RRM) and the relaying techniques. Chapter 3 explains the implementation of OFDM generation and reception that how an OFDM signal is generated and transmitted through the channel and how it is recovered at the receiver. Chapter 4 could be considered as the main part of thesis. It focuses on the simulation framework and the code. We have followed the paper â€Å"Subcarrier Allocation for multiuser two-way OFDMA Relay networks with Fairness Constraints†. In this section we have tried to implement the Dynamic Resource Allocation algorithm in order to achieve the maximum sum rate. Results are also discussed at the end of the end of the chapter. 2 Literature Review Introduction: First section of this Chapter gives a brief overview about OFDMA.OFDMA basically is the combination of Orthogonal Frequency Division Multiplexing (OFDM) and Frequency Division Multiplexing Access (FDMA).OFDMA provides high data rates even through multipath fading channels. In order to understand OFDMA, we must have brief introduction to Modulation, Multiple Access, Propagation mechanisms, its effects and its impairments while using OFDMA. 2.1 Modulation Modulation is the method of mapping data with change in carrier phase, amplitude, frequency or the combination [11]. There are two types of modulation techniques named as Single Carrier Modulation (SCM) Transmission Technique or Multicarrier Modulation (MCM) Transmission Technique. [12] Single Carrier Modulation (SCM) In single carrier transmission modulation (SCM) transmission, information is modulated using adjustment of frequency, phase and amplitude of a single carrier [12]. Multi Carrier Modulation (MCM) In multicarrier modulation transmission, input bit stream is split into several parallel bit streams then each bit stream simultaneously modulates with several sub-carriers (SCs) [12]. 2.2 Multiplexing Multiplexing is the method of sharing bandwidth and resources with other data channels. Multiplexing is sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end [13]. 2.2.1 Analog Transmission In analog transmission, signals are multiplexed using frequency division multiplexing (FDM), in which the carrier bandwidth is divided into sub channels of different frequency widths,and each signal is carried at the same time in parallel. 2.2.2 Digital Transmission In digital transmission, signals are commonly multiplexed using time-division multiplexing (TDM), in which the multiple signals are carried over the same channel in alternating time slots. 2.2.3 Need for OFDMA General wireless cellular systems are multi-users systems. We have limited radio resources as limited bandwidth and limited number of channels. The radio resources must be shared among multiple users. So OFDM is a better choice in this case. OFDM is the combination of modulation and multiplexing. It may be a modulation technique if we analyze the relation between input and output signals. It may be a multiplexing technique if we analyze the output signal which is the linear sum of modulated signal. In OFDM the signal is firstly split into sub channels, modulated and then re-multiplexed to create OFDM carrier. The spacing between carriers is such that they are orthogonal to one another. Therefore there is no need of guard band between carriers. In this way we are saving the bandwidth and utilizing our resources efficiently. 2.3 Radio Propagation Mechanisms There are 3 propagation mechanisms: Reflection, Diffraction and Scattering. These 3 phenomenon cause distortion in radio signal which give rise to propagation losses and fading in signals [14]. 2.3.1 Reflection Reflection occurs when a propagating Electro-Magnetic (EM) wave impinges upon an object which has very large dimensions as compared to the wavelength of the propagating wave. Reflections occur from the surface of the earth and from buildings and walls. 2.3.2 Diffraction When the radio path between the transmitter and receiver is obstructed by a surface that has sharp irregularities (edges), diffraction occurs. The secondary waves resulting from the obstructing surface are present throughout the space and even behind the obstacle, giving rise to a bending of waves around the obstacle, even when a line-of-sight path does not exist between transmitter and receiver. At high frequencies, diffraction, like reflection, depends on the geometry of the object, as well as the amplitude, phase and polarization of the incident wave at the point of diffraction. 2.3.3 Scattering When the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength, and where the number of obstacles per unit volume is large. Scattered waves are produced by rough surfaces, small objects or by other irregularities in the channel. In practice, foliage, street signs and lamp posts produce scattering in a mobile radio communications system. 2.4 Effects of Radio Propagation Mechanisms The three basic propagation mechanisms namely reflection, diffraction and scattering as we have explained above affect on the signal as it passes through the channel. These three radio propagation phenomena can usually be distinguished as large-scale path loss, shadowing and multipath fading [14][15]. 2.4.1 Path Loss Path Lossis the attenuation occurring by an electromagnetic wave in transit from a transmitter to a receiver in a telecommunication system. In simple words, it governs the deterministic attenuation power depending only upon the distance between two communicating entities. It is considered as large scale fading because it does not change rapidly. 2.4.2 Shadowing Shadowingis the result of movement of transmitter, receiver or any channel component referred to as (obstacles). Shadowing is a statistical parameter. Shadowing follows a log-normal distribution about the values governed by path loss. Although shadowing depends heavily upon the channel conditions and density of obstacles in the channel, it is also normally considered a large scale fading component alongside path loss. 2.4.3 Multipath Fading Multipath Fadingis the result of multiple propagation paths which are created by reflection, diffraction and scattering. When channel has multiple paths. Each of the paths created due to these mechanisms may have its characteristic power, delay and phase. So receiver will be receiving a large number of replicas of initially transmitted signal at each instant of time. The summation of these signals at receiver may cause constructive or destructive interferences depending upon the delays and phases of multiple signals. Due to its fast characteristic nature, multipath fading is called small scale fading. 2.5 Orthogonal Frequency Division Multiplexing (OFDM) Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multicarrier modulation that is robust to multi-path radio channel impairments [15]. Now-a-days it is widely accepted that OFDM is the most promising scheme in future high data-rate broadband wireless communication systems. OFDM is a special case of MCM transmission. In OFDM, high data rate input bit stream or data is first converted into several parallel bit stream, than each low rate bit stream is modulated with subcarrier. The several subcarriers are closely spaced. However being orthogonal they do not interfere with each other. 2.5.1 Orthognality Signals are orthogonal if they are mutually independent of each other. Orthogonality is a property that allows multiple information signals to be transmitted perfectly over a common channel and detected, without interference. Loss of orthogonality results in blurring between these information signals and degradation in communications. Many common multiplexing schemes are inherently orthogonal. The term OFDM has been reserved for a special form of FDM. The subcarriers in an OFDM signal are spaced as close as is theoretically possible while maintain orthogonality between them.In FDM there needs a guard band between channels to avoid interference between channels. The addition of guard band between channels greatly reduces the spectral efficiency. In OFDM, it was required to arrange sub carriers in such a way that the side band of each sub carrier overlap and signal is received without interference. The sub-carriers (SCs) must be orthogonal to each other, which eliminates the guard band and improves the spectral efficiency . 2.5.2 Conditions of orthogonality 2.5.2.1 Orthogonal Vectors Vectors A and B are two different vectors, they are said to be orthogonal if their dot product is zero 2.6 OFDM GENERATION AND RECEPTION OFDM signals are typically generated digitally due to the complexity of implementation in the analog domain. The transmission side is used to transmit digital data by mapping the subcarrier amplitude and phase. It then transforms this spectral representation of the data into the time domain using an Inverse Discrete Fourier Transform (IDFT) but due to much more computational efficiency in Inverse Fast Fourier Transform (IFFT), IFFT is used in all practical systems. The receiver side performs the reverse operations of the transmission side, mixing the RF signal to base band for processing, and then a Fast Fourier Transform (FFT) is employed to analyze the signal in the frequency domain. The demodulation of the frequency domain signal is then performed in order to obtain the transmitted digital data. The IFFT and the FFT are complementary function and the most suitable term depends on whether the signal is being recovered or transmitted but the cases where the signal is independent of this distinction then these terms can be used interchangeably [15]. 2.6.1 OFDM Block Diagram 2.6.2 Implementation of OFDM Block Diagram 2.6.2.1 Serial to Parallel Conversion: In an OFDM system, each channel can be broken down into number of sub-carriers. The use of sub-carriers can help to increase the spectral efficiency but requires additional processing by the transmitter and receiver which is necessary to convert a serial bit stream into several parallel bit streams to be divided among the individual carriers. This makes the processing faster as well as is used for mapping symbols on sub-carriers. 2.6.2.2 Modulation of Data: Once the bit stream has been divided among the individual sub-carriers by the use of serial to parallel converter, each sub-carrier is modulated using 16 QAM scheme as if it was an individual channel before all channels are combined back together and transmitted as a whole. 2.6.2.3 Inverse Fourier Transform: The role of the IFFT is to modulate each sub-channel onto the appropriate carrier thus after the required spectrum is worked out, an inverse Fourier transform is used to find the corresponding time domain waveform. 2.6.2.4 Parallel to Serial Conversion: Once the inverse Fourier transform has been done each symbol must be combined together and then transmitted as one signal. Thus, the parallel to serial conversion stage is the process of summing all sub-carriers and combining them into one signal 2.6.2.5 Channel: The OFDM signal is then transmitted over a channel with AWGN having SNR of 10 dB. 2.6.2.6 Receiver: The receiver basically does the reverse operations to the transmitter. The FFT of each symbol is taken to find the original transmitted spectrum. The phase angle of each transmission carrier is then evaluated and converted back to the data word by demodulating the received phase. The data words are then combined back to the same word size as the original data. 2.7 OFDMA in a broader perspective OFDM is a modulation scheme that allows digital data to be efficiently and reliably transmitted over a radio channel, even in multipath environments [17]. OFDM transmits data by using a large number of narrow bandwidth carriers. These carriers are regularly spaced in frequency, forming a block of spectrum. The frequency spacing and time synchronization of the carriers is chosen in such a way that the carriers are orthogonal, meaning that they do not interfere with each other. This is despite the carriers overlapping each other in the frequency domain [18]. The name ‘OFDM is derived from the fact that the digital data is sent using many carriers, each of a different frequency (Frequency Division Multiplexing) and these carriers are orthogonal to each other [19]. 2.7.1 History of OFDMA The origins of OFDM development started in the late 1950s with the introduction of Frequency Division Multiplexing (FDM) for data communications. In 1966 Chang patented the structure of OFDM and published the concept of using orthogonal overlapping multi-tone signals for data communications. In 1971 Weinstein introduced the idea of using a Discrete Fourier Transform (DFT) for Implementation of the generation and reception of OFDM signals, eliminating the requirement for banks of analog subcarrier oscillators. This presented an opportunity for an easy implementation of OFDM, especially with the use of Fast Fourier Transforms (FFT), which are an efficient implementation of the DFT. This suggested that the easiest implementation of OFDM is with the use of Digital Signal Processing (DSP), which can implement FFT algorithms. It is only recently that the advances in integrated circuit technology have made the implementation of OFDM cost effective. The reliance on DSP prevented the wide spread use of OFDM during the early development of OFDM. It wasnt until the late 1980s that work began on the development of OFDM for commercial use, with the introduction of the Digital Audio Broadcasting (DAB) system. 2.7.2 Advantages using OFDMA There are some advantages using OFDMA. OFDM is a highly bandwidth efficient scheme because different sub-carriers are orthogonal but they are overlapping. Flexible and can be made adaptive; different modulation schemes for subcarriers, bit loading, adaptable bandwidth/data rates possible. Has excellent ICI performance because of addition of cyclic prefix. In OFDM equalization is performed in frequency domain which becomes very easy as compared to the time domain equalization. Very good at mitigating the effects of delay spread. Due to the use of many sub-carriers, the symbol duration on the sub-carriers is increased, relative to delay spread. ISI is avoided through the use of guard interval. Resistant to frequency selective fading as compared to single carrier system. Used for high data rate transmission. OFDMA provides flexibility of deployment across a variety of frequency bands with little need for modification is of paramount importance. A single frequency network can be used to provide excellent coverage and good frequency re-use. OFDMA offers frequency diversity by spreading the carriers all over the used spectrum. 2.7.3 Challenges using OFDMA These are the difficulties we have to face while using OFDMA [20][21][22], The OFDM signal suffers from a very high peak to average power ratio (PAPR) therefore it requires transmitter RF power amplifiers to be sufficiently linear in the range of high input power. Sensitive to carrier frequency offset, needs frequency offset correction in the receiver. Sensitive to oscillator phase noise, clean and stable oscillator required. The use of guard interval to mitigate ISI affects the bandwidth efficiency. OFDM is sensitive to Doppler shift frequency errors offset the receiver and if not corrected the orthogonality between the carriers is degraded. If only a few carriers are assigned to each user the resistance to selective fading will be degraded or lost. It has a relatively high sensitivity to frequency offsets as this degrades the orthogonality between the carriers. It is sensitive to phase noise on the oscillators as this degrades the orthogonaility between the carriers. 2.7.4 Comparison with CDMA in terms of benefits 2.7.4.2 CDMA Advantages: CDMA has some advantages over OFDMA [22], Not as complicated to implement as OFDM based systems. As CDMA has a wide bandwidth, it is difficult to equalise the overall spectrum significant levels of processing would be needed for this as it consists of a continuous signal and not discrete carriers. Not as easy to aggregate spectrum as for OFDM. 2.7.5 OFDMA in the Real World: UMTS, the European standard for the 3G cellular mobile communications, and IEEE 802.16, a broadband wireless access standard for metropolitan area networks (MAN), are two live examples for industrial support of OFDMA. Table 1 shows the basic parameters of these two systems. Table 1. OFDMA system parameters in the UMTS and IEEE 802.16 standards 2.8 Radio Resource Management In second section of this chapter we will discuss radio resource management schemes, why we need them and how they improve the efficiency of the network. Radio resource management is the system level control of co-channel interference and other radio transmission characteristics in wireless communication systems. Radio resource management involves algorithms and strategies for controlling parameters such as Transmit power Sub carrier allocation Data rates Handover criteria Modulation scheme Error coding scheme, etc 2.8.1 Study of Radio Resource Management End-to-end reconfigurability has a strong impact on all aspects of the system, ranging from the terminal, to the air interface, up to the network side. Future network architectures must be flexible enough to support scalability as well as reconfigurable network elements, in order to provide the best possible resource management solutions in hand with cost effective network deployment. The ultimate aim is to increase spectrum efficiency through the use of more flexible spectrum allocation and radio resource management schemes, although suitable load balancing mechanisms are also desirable to maximize system capacity, to optimize QoS provision, and to increase spectrum efficiency. Once in place, mobile users will benefit from this by being able to access required services when and where needed, at an affordable cost. From an engineering point of view, the best possible solution can only be achieved when elements of the radio network are properly configured and suitable radio resource m anagement approaches/algorithms are applied. In other words, the efficient management of the whole reconfiguration decision process is necessary, in order to exploit the advantages provided by reconfigurability. For this purpose, future mobile radio networks must meet the challenge of providing higher quality of service through supporting increased mobility and throughput of multimedia services, even considering scarcity of spectrum resources. Although the size of frequency spectrum physically limits the capacity of radio networks, effective solutions to increase spectrum efficiency can optimize usage of available capacity. Through inspecting the needs of relevant participants in a mobile communication system, i.e., the Terminal, User, Service and Network, effective solutions can be used to define the communication configuration between the Terminal and Network, dependent on the requirements of Services demanded by Users. In other words, it is necessary to identify proper communications mechanisms between communications apparatus, based on the characteristics of users and their services. This raises further questions about how to manage traffic in heterogeneous networks in an efficient way. 2.8.2 Methods of RRM 2.8.2.1 Network based functions Admission control (AC) Load control (LC) Packet scheduler (PS) Resource Manager (RM) Admission control In the decision procedure AC will use threshold form network planning and from Interference measurements. The new connection should not impact the planned coverage and quality of existing Connections. (During the whole connection time.) AC estimates the UL and DL load increase which new connection would produce. AC uses load information from LC and PC. Load change depends on attributes of RAB: traffic and quality parameters. If UL or DL limit threshold is exceeded the RAB is not admitted. AC derives the transmitted bit rate, processing gain, Radio link initial quality parameters, target BER, BLER, Eb/No, SIR target. AC manages the bearer mapping The L1 parameters to be used during the call. AC initiates the forced call release, forced inter-frequency or intersystem handover. Load control Reason of load control Optimize the capacity of a cell and prevent overload The interference main resource criteria. LC measures continuously UL and DL interference. RRM acts based on the measurements and parameters from planning Preventive load control In normal conditions LC takes care that the network is not overloaded and remains Stable. Overload condition . LC is responsible for reducing the load and bringing the network back into operating area. Fast LC actions in BTS Lower SIR target for the uplink inner-loop PC. LC actions located in the RNC. Interact with PS and throttle back packet data traffic. Lower bit rates of RT users.(speech service or CS data). WCDMA interfrequency or GSM intersystem handover. Drop single calls in a controlled manner. 2.8.2.3 Connection based functions Handover Control (HC) Power Control (PC) Power control Uplink open loop power control. Downlink open loop power control. Power in downlink common channels. Uplink inner (closed) loop power control. Downlink inner (closed) loop power control. Outer loop power control. Power control in compressed mode. Handover Intersystem handover. Intrafrequency handover. Interfrequency handover. Intersystem handover. Hard handover (HHO). All the old radio links of an MS are released before the new radio links are established. Soft handover (SHO) SMS is simultaneously controlled by two or more cells belonging to different BTS of the same RNC or to different RNC. MS is controlled by at least two cells under one BTS. Mobile evaluated handover (MEHO) The UE mai Radio Resource Management in OFDMA Networks Radio Resource Management in OFDMA Networks 1 Introduction The convenience and popularity of wireless technology has now extended into multimedia communications, where it poses a unique challenge for transmitting high rate voice, image, and data signals simultaneously, synchronously, and virtually error-free. That challenge is currently being met through Orthogonal Frequency Division Multiplexing (OFDM), an interface protocol that divides incoming data streams into sub-streams with overlapping frequencies that can then be transmitted in parallel over orthogonal subcarriers [2,3]. To allow multiple accesses in OFDM , Orthogonal Frequency Division Multiple Access (OFDMA) was introduced. Relaying techniques, along with OFDMA, are used to achieve high data rate and high spectral efficiency. 1.1 Orthogonal Frequency Division Multiple Access OFDMA, an interface protocol combining features of OFDM and frequency division multiple access (FDMA)., was developed to move OFDM technology from a fixed-access wireless system to a true cellular system with mobility with same underlying technology, but more flexibility was defined in the operation of the system [1,8]. In OFDMA, subcarriers are grouped into larger units, referred to as sub-channels, and these sub-channels are further grouped into bursts which can be allocated to wireless users [4]. 1.2 Relay-Enhanced Networks In cellular systems, a way to achieve remarkable increase in data rate, but without claiming for more bandwidth, is to shrink cell sizes, however, with smaller cells more base stations (BSs) are needed to cover a same area due to which deployment and networking of new BSs acquire significant costs [5]. An alternative solution to this problem is to deploy smart relay stations (RSs), which can communication with each other and with BSs through wireless connections reducing systems cost. A relay station (RS), also called repeater or multi-hop station, is a radio system that helps to improve coverage and capacity of a base station (BS) and the resulting networks employing relay stations are sometimes called cooperative networks [6]. 1.3 Technological Requirement The continuously evolving wireless multimedia services push the telecommunication industries to set a very high data rate requirement for next generation mobile communication systems. As spectrum resource becomes very scarce and expensive, how to utilize this resource wisely to fulfil high quality user experiences is a very challenging research topic. Orthogonal frequency-division multiple access (OFDMA)-based RRM schemes together with relaying techniques allocate different portions of radio resources to different users in both the frequency and time domains and offers a promising technology for providing ubiquitous high-data-rate coverage with comparatively low cost than deploying multiple base stations [5]. Although wireless services are the demand of future due to their mobility and low cost infrastructure but along with this they suffer serious channel impairments. In particular, the channel suffers from frequency selective fading and distance dependent fading (i.e., large-scale fading) [1, 8]. While frequency selective fading results in inter-symbol-interference (ISI), large-scale fading attenuates the transmitted signal below a level at which it can be correctly decoded. Orthogonal Frequency-Division Multiple Access (OFDMA) relay-enhanced cellular network, the integration of multi-hop relaying with OFDMA infrastructure, has become one of the most promising solutions for next-generation wireless communications. 1.3.1 Frequency Selective Fading In wireless communications, the transmitted signal is typically reaching the receiver through multiple propagation paths (reflections from buildings, etc.), each having a different relative delay and amplitude. This is called multipath propagation and causes different parts of the transmitted signal spectrum to be attenuated differently, which is known as frequency-selective fading. In addition to this, due to the mobility of transmitter and/or receiver or some other time-varying characteristics of the transmission environment, the principal characteristics of the wireless channel change in time which results in time-varying fading of the received signal [9]. 1.3.2 Large Scale Fading Large scale fading is explained by the gradual loss of received signal power (since it propagates in all directions) with transmitter-receiver (T-R) separation distance. These phenomenonss cause attenuation in the signal and decrease in its power. To overcome this we use diversity and multi-hop relaying. 1.3.3 Diversity Diversity refers to a method for improving the reliability of a message signal by using two or morecommunication channelswith different characteristics. Diversity plays an important role in combatingfadingandco-channel interferenceand avoidingerror bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver [10]. 1.4 Proposed Simulation Model We developed a simulation model in which each user-pair is allocated dynamically a pair of relay and subcarrier in order to maximize its achievable sum-rate while satisfying the minimum rate requirement. The algorithm and the results of the simulation model are given in chapter 4. 1.5 Objectives The objective of our project is to have a detail overview of the literature regarding Orthogonal Frequency Division Multiple Access (OFDMA), Radio Resource Management (RRM) and Relaying techniques. After literature review we developed a simulation framework in which we will try to use minimum resources to get maximum throughput by using dynamic resource allocation. 1.6 Tools For the design and implementation of proposed Algorithm, we have used the following tools MATLAB Smart Draw Corel Draw 1.7 Overview Chapter 2 contains the literature review. It explains the basic principles of OFDMA, Radio Resource Management (RRM) and the relaying techniques. Chapter 3 explains the implementation of OFDM generation and reception that how an OFDM signal is generated and transmitted through the channel and how it is recovered at the receiver. Chapter 4 could be considered as the main part of thesis. It focuses on the simulation framework and the code. We have followed the paper â€Å"Subcarrier Allocation for multiuser two-way OFDMA Relay networks with Fairness Constraints†. In this section we have tried to implement the Dynamic Resource Allocation algorithm in order to achieve the maximum sum rate. Results are also discussed at the end of the end of the chapter. 2 Literature Review Introduction: First section of this Chapter gives a brief overview about OFDMA.OFDMA basically is the combination of Orthogonal Frequency Division Multiplexing (OFDM) and Frequency Division Multiplexing Access (FDMA).OFDMA provides high data rates even through multipath fading channels. In order to understand OFDMA, we must have brief introduction to Modulation, Multiple Access, Propagation mechanisms, its effects and its impairments while using OFDMA. 2.1 Modulation Modulation is the method of mapping data with change in carrier phase, amplitude, frequency or the combination [11]. There are two types of modulation techniques named as Single Carrier Modulation (SCM) Transmission Technique or Multicarrier Modulation (MCM) Transmission Technique. [12] Single Carrier Modulation (SCM) In single carrier transmission modulation (SCM) transmission, information is modulated using adjustment of frequency, phase and amplitude of a single carrier [12]. Multi Carrier Modulation (MCM) In multicarrier modulation transmission, input bit stream is split into several parallel bit streams then each bit stream simultaneously modulates with several sub-carriers (SCs) [12]. 2.2 Multiplexing Multiplexing is the method of sharing bandwidth and resources with other data channels. Multiplexing is sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end [13]. 2.2.1 Analog Transmission In analog transmission, signals are multiplexed using frequency division multiplexing (FDM), in which the carrier bandwidth is divided into sub channels of different frequency widths,and each signal is carried at the same time in parallel. 2.2.2 Digital Transmission In digital transmission, signals are commonly multiplexed using time-division multiplexing (TDM), in which the multiple signals are carried over the same channel in alternating time slots. 2.2.3 Need for OFDMA General wireless cellular systems are multi-users systems. We have limited radio resources as limited bandwidth and limited number of channels. The radio resources must be shared among multiple users. So OFDM is a better choice in this case. OFDM is the combination of modulation and multiplexing. It may be a modulation technique if we analyze the relation between input and output signals. It may be a multiplexing technique if we analyze the output signal which is the linear sum of modulated signal. In OFDM the signal is firstly split into sub channels, modulated and then re-multiplexed to create OFDM carrier. The spacing between carriers is such that they are orthogonal to one another. Therefore there is no need of guard band between carriers. In this way we are saving the bandwidth and utilizing our resources efficiently. 2.3 Radio Propagation Mechanisms There are 3 propagation mechanisms: Reflection, Diffraction and Scattering. These 3 phenomenon cause distortion in radio signal which give rise to propagation losses and fading in signals [14]. 2.3.1 Reflection Reflection occurs when a propagating Electro-Magnetic (EM) wave impinges upon an object which has very large dimensions as compared to the wavelength of the propagating wave. Reflections occur from the surface of the earth and from buildings and walls. 2.3.2 Diffraction When the radio path between the transmitter and receiver is obstructed by a surface that has sharp irregularities (edges), diffraction occurs. The secondary waves resulting from the obstructing surface are present throughout the space and even behind the obstacle, giving rise to a bending of waves around the obstacle, even when a line-of-sight path does not exist between transmitter and receiver. At high frequencies, diffraction, like reflection, depends on the geometry of the object, as well as the amplitude, phase and polarization of the incident wave at the point of diffraction. 2.3.3 Scattering When the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength, and where the number of obstacles per unit volume is large. Scattered waves are produced by rough surfaces, small objects or by other irregularities in the channel. In practice, foliage, street signs and lamp posts produce scattering in a mobile radio communications system. 2.4 Effects of Radio Propagation Mechanisms The three basic propagation mechanisms namely reflection, diffraction and scattering as we have explained above affect on the signal as it passes through the channel. These three radio propagation phenomena can usually be distinguished as large-scale path loss, shadowing and multipath fading [14][15]. 2.4.1 Path Loss Path Lossis the attenuation occurring by an electromagnetic wave in transit from a transmitter to a receiver in a telecommunication system. In simple words, it governs the deterministic attenuation power depending only upon the distance between two communicating entities. It is considered as large scale fading because it does not change rapidly. 2.4.2 Shadowing Shadowingis the result of movement of transmitter, receiver or any channel component referred to as (obstacles). Shadowing is a statistical parameter. Shadowing follows a log-normal distribution about the values governed by path loss. Although shadowing depends heavily upon the channel conditions and density of obstacles in the channel, it is also normally considered a large scale fading component alongside path loss. 2.4.3 Multipath Fading Multipath Fadingis the result of multiple propagation paths which are created by reflection, diffraction and scattering. When channel has multiple paths. Each of the paths created due to these mechanisms may have its characteristic power, delay and phase. So receiver will be receiving a large number of replicas of initially transmitted signal at each instant of time. The summation of these signals at receiver may cause constructive or destructive interferences depending upon the delays and phases of multiple signals. Due to its fast characteristic nature, multipath fading is called small scale fading. 2.5 Orthogonal Frequency Division Multiplexing (OFDM) Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multicarrier modulation that is robust to multi-path radio channel impairments [15]. Now-a-days it is widely accepted that OFDM is the most promising scheme in future high data-rate broadband wireless communication systems. OFDM is a special case of MCM transmission. In OFDM, high data rate input bit stream or data is first converted into several parallel bit stream, than each low rate bit stream is modulated with subcarrier. The several subcarriers are closely spaced. However being orthogonal they do not interfere with each other. 2.5.1 Orthognality Signals are orthogonal if they are mutually independent of each other. Orthogonality is a property that allows multiple information signals to be transmitted perfectly over a common channel and detected, without interference. Loss of orthogonality results in blurring between these information signals and degradation in communications. Many common multiplexing schemes are inherently orthogonal. The term OFDM has been reserved for a special form of FDM. The subcarriers in an OFDM signal are spaced as close as is theoretically possible while maintain orthogonality between them.In FDM there needs a guard band between channels to avoid interference between channels. The addition of guard band between channels greatly reduces the spectral efficiency. In OFDM, it was required to arrange sub carriers in such a way that the side band of each sub carrier overlap and signal is received without interference. The sub-carriers (SCs) must be orthogonal to each other, which eliminates the guard band and improves the spectral efficiency . 2.5.2 Conditions of orthogonality 2.5.2.1 Orthogonal Vectors Vectors A and B are two different vectors, they are said to be orthogonal if their dot product is zero 2.6 OFDM GENERATION AND RECEPTION OFDM signals are typically generated digitally due to the complexity of implementation in the analog domain. The transmission side is used to transmit digital data by mapping the subcarrier amplitude and phase. It then transforms this spectral representation of the data into the time domain using an Inverse Discrete Fourier Transform (IDFT) but due to much more computational efficiency in Inverse Fast Fourier Transform (IFFT), IFFT is used in all practical systems. The receiver side performs the reverse operations of the transmission side, mixing the RF signal to base band for processing, and then a Fast Fourier Transform (FFT) is employed to analyze the signal in the frequency domain. The demodulation of the frequency domain signal is then performed in order to obtain the transmitted digital data. The IFFT and the FFT are complementary function and the most suitable term depends on whether the signal is being recovered or transmitted but the cases where the signal is independent of this distinction then these terms can be used interchangeably [15]. 2.6.1 OFDM Block Diagram 2.6.2 Implementation of OFDM Block Diagram 2.6.2.1 Serial to Parallel Conversion: In an OFDM system, each channel can be broken down into number of sub-carriers. The use of sub-carriers can help to increase the spectral efficiency but requires additional processing by the transmitter and receiver which is necessary to convert a serial bit stream into several parallel bit streams to be divided among the individual carriers. This makes the processing faster as well as is used for mapping symbols on sub-carriers. 2.6.2.2 Modulation of Data: Once the bit stream has been divided among the individual sub-carriers by the use of serial to parallel converter, each sub-carrier is modulated using 16 QAM scheme as if it was an individual channel before all channels are combined back together and transmitted as a whole. 2.6.2.3 Inverse Fourier Transform: The role of the IFFT is to modulate each sub-channel onto the appropriate carrier thus after the required spectrum is worked out, an inverse Fourier transform is used to find the corresponding time domain waveform. 2.6.2.4 Parallel to Serial Conversion: Once the inverse Fourier transform has been done each symbol must be combined together and then transmitted as one signal. Thus, the parallel to serial conversion stage is the process of summing all sub-carriers and combining them into one signal 2.6.2.5 Channel: The OFDM signal is then transmitted over a channel with AWGN having SNR of 10 dB. 2.6.2.6 Receiver: The receiver basically does the reverse operations to the transmitter. The FFT of each symbol is taken to find the original transmitted spectrum. The phase angle of each transmission carrier is then evaluated and converted back to the data word by demodulating the received phase. The data words are then combined back to the same word size as the original data. 2.7 OFDMA in a broader perspective OFDM is a modulation scheme that allows digital data to be efficiently and reliably transmitted over a radio channel, even in multipath environments [17]. OFDM transmits data by using a large number of narrow bandwidth carriers. These carriers are regularly spaced in frequency, forming a block of spectrum. The frequency spacing and time synchronization of the carriers is chosen in such a way that the carriers are orthogonal, meaning that they do not interfere with each other. This is despite the carriers overlapping each other in the frequency domain [18]. The name ‘OFDM is derived from the fact that the digital data is sent using many carriers, each of a different frequency (Frequency Division Multiplexing) and these carriers are orthogonal to each other [19]. 2.7.1 History of OFDMA The origins of OFDM development started in the late 1950s with the introduction of Frequency Division Multiplexing (FDM) for data communications. In 1966 Chang patented the structure of OFDM and published the concept of using orthogonal overlapping multi-tone signals for data communications. In 1971 Weinstein introduced the idea of using a Discrete Fourier Transform (DFT) for Implementation of the generation and reception of OFDM signals, eliminating the requirement for banks of analog subcarrier oscillators. This presented an opportunity for an easy implementation of OFDM, especially with the use of Fast Fourier Transforms (FFT), which are an efficient implementation of the DFT. This suggested that the easiest implementation of OFDM is with the use of Digital Signal Processing (DSP), which can implement FFT algorithms. It is only recently that the advances in integrated circuit technology have made the implementation of OFDM cost effective. The reliance on DSP prevented the wide spread use of OFDM during the early development of OFDM. It wasnt until the late 1980s that work began on the development of OFDM for commercial use, with the introduction of the Digital Audio Broadcasting (DAB) system. 2.7.2 Advantages using OFDMA There are some advantages using OFDMA. OFDM is a highly bandwidth efficient scheme because different sub-carriers are orthogonal but they are overlapping. Flexible and can be made adaptive; different modulation schemes for subcarriers, bit loading, adaptable bandwidth/data rates possible. Has excellent ICI performance because of addition of cyclic prefix. In OFDM equalization is performed in frequency domain which becomes very easy as compared to the time domain equalization. Very good at mitigating the effects of delay spread. Due to the use of many sub-carriers, the symbol duration on the sub-carriers is increased, relative to delay spread. ISI is avoided through the use of guard interval. Resistant to frequency selective fading as compared to single carrier system. Used for high data rate transmission. OFDMA provides flexibility of deployment across a variety of frequency bands with little need for modification is of paramount importance. A single frequency network can be used to provide excellent coverage and good frequency re-use. OFDMA offers frequency diversity by spreading the carriers all over the used spectrum. 2.7.3 Challenges using OFDMA These are the difficulties we have to face while using OFDMA [20][21][22], The OFDM signal suffers from a very high peak to average power ratio (PAPR) therefore it requires transmitter RF power amplifiers to be sufficiently linear in the range of high input power. Sensitive to carrier frequency offset, needs frequency offset correction in the receiver. Sensitive to oscillator phase noise, clean and stable oscillator required. The use of guard interval to mitigate ISI affects the bandwidth efficiency. OFDM is sensitive to Doppler shift frequency errors offset the receiver and if not corrected the orthogonality between the carriers is degraded. If only a few carriers are assigned to each user the resistance to selective fading will be degraded or lost. It has a relatively high sensitivity to frequency offsets as this degrades the orthogonality between the carriers. It is sensitive to phase noise on the oscillators as this degrades the orthogonaility between the carriers. 2.7.4 Comparison with CDMA in terms of benefits 2.7.4.2 CDMA Advantages: CDMA has some advantages over OFDMA [22], Not as complicated to implement as OFDM based systems. As CDMA has a wide bandwidth, it is difficult to equalise the overall spectrum significant levels of processing would be needed for this as it consists of a continuous signal and not discrete carriers. Not as easy to aggregate spectrum as for OFDM. 2.7.5 OFDMA in the Real World: UMTS, the European standard for the 3G cellular mobile communications, and IEEE 802.16, a broadband wireless access standard for metropolitan area networks (MAN), are two live examples for industrial support of OFDMA. Table 1 shows the basic parameters of these two systems. Table 1. OFDMA system parameters in the UMTS and IEEE 802.16 standards 2.8 Radio Resource Management In second section of this chapter we will discuss radio resource management schemes, why we need them and how they improve the efficiency of the network. Radio resource management is the system level control of co-channel interference and other radio transmission characteristics in wireless communication systems. Radio resource management involves algorithms and strategies for controlling parameters such as Transmit power Sub carrier allocation Data rates Handover criteria Modulation scheme Error coding scheme, etc 2.8.1 Study of Radio Resource Management End-to-end reconfigurability has a strong impact on all aspects of the system, ranging from the terminal, to the air interface, up to the network side. Future network architectures must be flexible enough to support scalability as well as reconfigurable network elements, in order to provide the best possible resource management solutions in hand with cost effective network deployment. The ultimate aim is to increase spectrum efficiency through the use of more flexible spectrum allocation and radio resource management schemes, although suitable load balancing mechanisms are also desirable to maximize system capacity, to optimize QoS provision, and to increase spectrum efficiency. Once in place, mobile users will benefit from this by being able to access required services when and where needed, at an affordable cost. From an engineering point of view, the best possible solution can only be achieved when elements of the radio network are properly configured and suitable radio resource m anagement approaches/algorithms are applied. In other words, the efficient management of the whole reconfiguration decision process is necessary, in order to exploit the advantages provided by reconfigurability. For this purpose, future mobile radio networks must meet the challenge of providing higher quality of service through supporting increased mobility and throughput of multimedia services, even considering scarcity of spectrum resources. Although the size of frequency spectrum physically limits the capacity of radio networks, effective solutions to increase spectrum efficiency can optimize usage of available capacity. Through inspecting the needs of relevant participants in a mobile communication system, i.e., the Terminal, User, Service and Network, effective solutions can be used to define the communication configuration between the Terminal and Network, dependent on the requirements of Services demanded by Users. In other words, it is necessary to identify proper communications mechanisms between communications apparatus, based on the characteristics of users and their services. This raises further questions about how to manage traffic in heterogeneous networks in an efficient way. 2.8.2 Methods of RRM 2.8.2.1 Network based functions Admission control (AC) Load control (LC) Packet scheduler (PS) Resource Manager (RM) Admission control In the decision procedure AC will use threshold form network planning and from Interference measurements. The new connection should not impact the planned coverage and quality of existing Connections. (During the whole connection time.) AC estimates the UL and DL load increase which new connection would produce. AC uses load information from LC and PC. Load change depends on attributes of RAB: traffic and quality parameters. If UL or DL limit threshold is exceeded the RAB is not admitted. AC derives the transmitted bit rate, processing gain, Radio link initial quality parameters, target BER, BLER, Eb/No, SIR target. AC manages the bearer mapping The L1 parameters to be used during the call. AC initiates the forced call release, forced inter-frequency or intersystem handover. Load control Reason of load control Optimize the capacity of a cell and prevent overload The interference main resource criteria. LC measures continuously UL and DL interference. RRM acts based on the measurements and parameters from planning Preventive load control In normal conditions LC takes care that the network is not overloaded and remains Stable. Overload condition . LC is responsible for reducing the load and bringing the network back into operating area. Fast LC actions in BTS Lower SIR target for the uplink inner-loop PC. LC actions located in the RNC. Interact with PS and throttle back packet data traffic. Lower bit rates of RT users.(speech service or CS data). WCDMA interfrequency or GSM intersystem handover. Drop single calls in a controlled manner. 2.8.2.3 Connection based functions Handover Control (HC) Power Control (PC) Power control Uplink open loop power control. Downlink open loop power control. Power in downlink common channels. Uplink inner (closed) loop power control. Downlink inner (closed) loop power control. Outer loop power control. Power control in compressed mode. Handover Intersystem handover. Intrafrequency handover. Interfrequency handover. Intersystem handover. Hard handover (HHO). All the old radio links of an MS are released before the new radio links are established. Soft handover (SHO) SMS is simultaneously controlled by two or more cells belonging to different BTS of the same RNC or to different RNC. MS is controlled by at least two cells under one BTS. Mobile evaluated handover (MEHO) The UE mai