Value Added Tax And The Implementation Of China Essay

Capstone paper Qiming Wang 9/11/2016 Value Added Tax and The Implementation in China Brief history of value added tax VAT was introduced in 1954 in France, being the invention on an engineer – Maurice Laure – who worked as a fiscal inspector, banking employee and as an employee of a big retailer. If at the beginning VAT was created and destined for big companies, from 1996, at the proposal of the Finance Minister, it begins to be applied also in the retail sector. At the end of his career, the tax author remembered: â€Å"In 1952-1953 I had the occasion to conceive a reform regarding the turnover taxation, that I named VAT. Proposed in the Parliament by the Finance Minister, it was rejected. Despite the fact that I wasn’t the adept of the production taxation, because it stifled finally the investments, I defended until the end my idea, and, when Edgar Faure became Finance Minister, he proposed my tax be introduced in the Finance Law for 1954. After many political negotiations, VAT passed through the Parliament and was voted, but not without adventures !† After the First World War, France had passed at the direct taxation on the expenses. In 1917 a proportional tax on the payers was introduced, and in 1920, this one was replaced with the tax on the total sales (turnover tax). If between 1925-1936, unique taxes on type of products were applied (they reached 30 taxes), starting with 1937 the unique tax on the production and the unique tax on the services were introduced. FromShow MoreRelatedValue Added Tax And Implementing China Essay2371 Words   |  10 Pagespaper Qiming Wang 9/11/2016 Value Added Tax and Implementation in China Introduction As a type of consumption tax, as of January 1 2014, 164 countries employ a Value-added Tax in the world. All Organization for Economic Co-operation and Development (OECD) members except the United States now applied VAT. According to the research by OECD committee, consumption tax was a large source of tax revenues, and â€Å"the VAT accounted on average for 6.6% of GDP and 19.5% in total tax revenues in OECD countriesRead MoreChina Has Increased Its Installed Wind Energy Capacity878 Words   |  4 Pages After passing of this law, China took a concerted effort towards increasing its renewable energy profile. China has increased its installed wind energy capacity from 1.260 GW to 62.36 GW from 2005 to 2011. This can be compared with the United States that saw an increased wind energy capacity from 8.7 GW to 45.98 GW in the same time period. This is a 10.2\% increase annually versus 6.2\% in the United States. As shown in figure ef{AC_Sys_Voltages}, China installed 45.6\% of the total wind energyRead MoreMongoli Developing Asian Country Dependent On External Trade Essay953 Words   |  4 Pages(â€Å"Trade Policy Review,† 2014), accounting for 28 percent of its GDP. In 2013, the largest export commodity was â€Å"coal; briquettes, ovoid and similar solid fuels manufactured from coal† (â€Å"Mongolia,† 2013); 94.6 percent of these total exports went to China, the United Kingdom and Canada. Other goods, such as gold, textiles and cashmere are the main exports of Mo ngolia to the European Union. Agriculture made up 27.9 percent of the GDP in 2013â€Å"The main export products of Mongolia to Russia are mainlyRead MoreValue Proposition775 Words   |  4 PagesValue Proposition Your value proposition can equip you with the following benefits to your business: * Create a strong differential between you and your competitors * Increase not only the quantity but the quality of prospective leads * Gain market share in your targeted segments * Assist you in enhancing tools that will help you close more business * Improve your operation efficiency iPod vs. Other MP3 Players - As early as 1996 MP3 players were available to the public forRead MoreEssay Business Analysis: Bargain Basement Books1555 Words   |  7 Pagesfollows through with the implementation of those objectives. In delegating authority to other government bodies, the Council focuses on matters of highest importance. Taxation: Finland’s taxes are high in comparison to other European countries. This is due in part to the revenue being used to help finance care for children, the elderly, health care, education, and security. (Taxation). For taxable income of a minimum of 64,500 euros, or approximately $87,965, the tax rate is 30.5% (Taxation inRead MoreBureaucratic And Government Organizations : Policies And Bottlenecks1586 Words   |  7 Pagesaccess to electricity and most of them are from developing countries Development and implementation of clean technology faces widely bureaucratic and institutional barrier. Institutional barriers include weak infrastructure to support any development and adoption of new technology and to implement performance standards as well as environmental standards. Economic barriers include high capital and implementation costs; less availability of world class technical expertise, difficulty in transformingRead MoreForeign Investment In China Case Study1419 Words   |  6 Pagesresearch that is conducted . 4.1 Key findings As Chinas aged care sector in China is shifting quickly and presenting substantial potential, the elderly population will have an increasing influence on the future of the country. Economically, the aging population will cause a burst in demand for elderly goods and services. Socially, the elderly’s attitudes towards nursing homes will challenge traditional Chinese family values such as the Confucianism influenced filial piety and set a standard for comingRead MoreZhujiag Iron and Steel Copmany1354 Words   |  6 Pagescompany’s bargaining power with supplier and created co-ordination problems. On March 2003, Zhang was appointed as the new president of ZISCo, to develop and implement new strategy to improve ZISCo’s long term competitive advantage. To implement value creation strategy, Zhang’s first task was to increase production volume and improve product quality through cross functional co-ordination at ZISCo. He also reduced material procurement costs and stabilizes supply sources through consolidation of itsRead MoreWhy Should China Ease Foreign Investors1526 Words   |  7 PagesAlthough the raise of China as a super economy was done by creating a market economy with socialist characteristics aimed at making profit and its maximization, the country has maintained state ownership of the means of production and remained a closed economy. In order to accept foreign investors to operate in China, the government imposes that they must hold majority ownership. Easing inbound investment into China’s economy would bring a multitude of benefits to China in cluding the internationalRead MoreAmerica s Diminishing Faith On Free Trade Essay1712 Words   |  7 Pageslike TPP† yet he tells Fox News that he is all for free trade â€Å"but it’s got to be fair† and wishes to go back to the days when America used to produce their own items. Along with the TTP, the presidential candidates propose to make adjustments with China, NAFTA, and to renegotiate tougher and fairer trade agreements. I believe the Heckscher Ohlin Model works along with Hillary Clinton’s and Donald Trump’s trade policies because wealthy nations like the United States trade with low wage nations at

Slavery And The Reconstruction Of The United States

In addition to the Europeans being criminals by inflicting pain and suffering, and doing horrific things to the Natives; we will now go to the crime that occurred to during slavery and the reconstruction. Like mentioned before, there have been many different ways that crime has been committed since the beginning of The United States of America. One of the very first crimes that were committed in America, was when the European settlers arrived to some land what they thought was the sub-continent of India but was actually now known as America, and labeling the indigenous peoples as savages, as the Europeans killed many of them off while trying to assimilate them. During the year of 1619, one of a few crimes that were committed was when the Dutch brought some of the first captured Africans to America, in which eventually changed what is now The United States and what it now stands for today. Although slavery was not documented and considered as a crime, it was a form of forcing individuals to produce hard labor against their will. The techniques of controlling the slaves were many and varied, and brutal. There were also laws set in place that helped with the control of slaves called Sla ves Codes. Slave codes were defined as laws that defined the low position held by slaves in the United States. As a slave, there were numerous of things that prohibited individuals of what they were not allowed to do. For example, such as voting, nor leave a plantation without a pass that statedShow MoreRelatedReconstruction : The Misadventures Of Post Civil War1116 Words   |  5 PagesTimothy Perdoch CCNY USSO 101 Prof. Van Natter Reconstruction (The Misadventures of Post-Civil War America) America: â€Å"The land of the free, and the home of the brave† (Key 7-8). When our forefathers overcame the colonial reign of the British Empire, they formed the United States of America based on the premise of enlightened ideals promoting life, ownership of land, and liberty. But after the revolution, the country’s problems were far from solved. The country’s post-revolution issues sparkedRead MoreThe American Civil War1418 Words   |  6 Pagesfired, smoke lingering in the air, people dying. The American Civil War had a huge impact on the United States. Two compromises took place before the start of the Civil War. These compromises include the Missouri Compromise and the Compromise of 1850. The Missouri Compromise dealt with the crisis in 1819 over Missouri entering the Union as a slave state. The compromise was â€Å"the first major crisis over slavery, and it shattered a tacit agreement between the two regions that had been in place since theRead More The Legacy Of The Reconstruction Era1473 Words   |  6 PagesThe reconstruction era was a time that then affected America in positive facets and negative aspects as well, and still affects America today. Thanks to the reconstruction era, there are several implementations that geared the world on the path in which it is today. Had it not been for some of the laws that were set in place African Americans may have not had many of the opportunities that were presented during the reconstruction period, therefore the years of oppression and cruelty might still beRead MoreHow Reconstruction Failed to Bring Equality to Freed Blacks Essay1383 Words   |  6 PagesHow Reconstruction Failed to Bring Equality to Freed Blacks After the Civil War, the government had changed from a republican rule to a democratic rule that had hatred towards the South because of conflicts that had arisen during the Civil War. The Northern Republicans wanted to punish the South by forming laws that terminated slavery and granted freed blacks the right to vote, the right to own land, the right to due process, and outlawed discrimination based on race; all were attempts to tryRead MoreSignificance Of The Reconstruction Act861 Words   |  4 PagesResponse Assignment 1 Part one – Define and describe the significance 1. Reconstruction Acts – after the civil war four bills were passed by the United States Congress in 1867 in order to bring the country back together, providing the process and criteria that would allow the Southern states with the exception Tennessee, readmission into the Union. (Ohio Civil War Central, 2015) The significance of the Reconstruction act was the division of the south into five military districts; loyal freedRead MoreThe United States And The Civil War1622 Words   |  7 PagesIndependence). According to the U.S. Constitution the purpose for which the United States was created was to establish a perfect union within the citizens of the U.S. through justice, safety, welfare and liberty. In my opinion, although the U.S. Constitution states this, I do not believe this perfect union is in favor for everyone in this country because of the unjust events that have taken places within this country such as slavery. I believe the U.S. Constitution purpose only applies to those who areRead MoreMexican American War1560 Words   |  7 Pagesor two): -The Mexican American War: The Mexican-American war was a fight for lad between the Untied States and Mexico where the United States defeated Mexico and gained over five hundred thousand miles of land. The land in known as the Southwest and makes up a vast majority of the United States. A major contributor to the war was the American belief of Manifest Destiny and showed how the United States wanted to extend their borders to the Pacific. The acquirement of the land did open up much room forRead MoreReconstruction Is The Effort Made In The United States1566 Words   |  7 PagesReconstruction is the effort made in the United States to restructure the political, legal, and economic systems in the states seceded from the Union. The Reconstruction Era last between the years of 1865-1877. The Civil War caused destruction and several deaths throughout the South in 1865. This struggle was compensated by radical Republicans who felt that they were in control of Southerners by punishing th em for wanting to preserve their southern tradition. How would the North and the South comeRead MoreReconstruction Of The United States1181 Words   |  5 PagesBy 1877, reconstruction had successfully restored the United States as a unified nation. Each Confederate state had thoroughly drafted state constitutions, pledged their loyalty to the United States government, and accepted the newly Thirteenth, Fourteenth, and Fifteenth Amendments. However, reconstruction inevitably failed the South. The legislation of Radical Republicans failed to give protection to freed slaves from further persecution of whites; and it also failed to fundamentally refabricateRead MoreThe Positive Impact Of Reconstruction1216 Words   |  5 PagesJust imagine that you were born when slavery was allowed in the United States. Better yet, imagine yourself as an African American/ black and being born into slavery. What would you do? Would you try to escape to freedom or remain a slave and serve â€Å"your master† until you die or until slavery is totally abolished? Well that’s when the Reconstruction Era comes in. The Civil War was a major cause that led to the Reconstruction Era. This was due to the Union winning the war between them and the South

Cja 314 Crime Data Free Essays

Crime Data Comparison Paper CJA/314 April 2, 2013 Paula Rutkowski Data Comparison The rates of any crime in the database are extremely different based on location and population. The two areas that are selected for this paper were Akron, Ohio, based on that I have family that reside there and it was very interesting looking at the statistics in this area. Also, another area chosen was Altoona, Pennsylvania, based on several friends/family is from that area as well. We will write a custom essay sample on Cja 314 Crime Data or any similar topic only for you Order Now This paper will cover crime data from 2007, 2008, 2009 based on Aggravated Assault cases in those areas. The statistics show dramatic changes within both areas over the years according to the Federal Bureau of Investigation. Reported Incidents The population of Akron, Ohio, was 699,760 in 2007. It is estimated that a total of 902 cases of aggravated assault was reported. In comparison the population of Altoona, Pennsylvania was 125,800 and the total population of reported cases of aggravated assault was 238. Altoona had a vastly smaller population than Akron and in turn had much less reported cases of aggravated assault. Crime in the United States by Metropolitan Statistical Area 2007. ) In 2008 the population of each area did not change very much. Akron increased by 154 people placing them at a population of 699,914, and Altoona decreased to a population of 125,036 dropping their total population by 764 people. Akron in 2008 had 1,137 reported aggravated assault cases and Altoona had 246 reported aggravated assault cases. (Crime in the United States by Metropolitan Statistical Area 200 8. ) In 2009 the population of each area increased. Akron had a large increase of 1,018 more people. Altoona’s population increased by only 33 people. Akron’s reported aggravated assault cases jumped to 1,248 an increase of 111 reported cases. However, Altoona’s reported aggravated assault cases only went up to 249. (Crime in the United States by Metropolitan Statistical Area, 2009. ) Rate of Crime in Area Altoona, Pennsylvania, had an approximate population of only 17. 96% of Akron, Ohio. In 2008 it decreased to 17. 86% of that of Akron, Ohio. In 2009 it was at 17. 84% of that of Akron, Ohio. Even with these percentages Altoona, Pennsylvania, did not fall below 19. 5% of aggravated assaults reported to law enforcement in Akron, Ohio. Conducting a comparison of population between both metro areas shows Altoona experienced 26. 38% of Akron’s aggravated assault cases in 2007, 21. 63% in 2008, and finally 19. 95 in 2009. When comparing statistical data is helpful to note that reported crime rates was based on known occurrences of the crime in a given area. E very year there is numerous crimes committed in every metropolitan city that go unreported to the proper law enforcement agency. Statistical data is only as good as the reporting of the crimes in each city. Rate Change Akron, Ohio, in 2007 had an aggravated assault rate of 128. 9 per 100,000 residents. Altoona, Pennsylvania, had an aggravated assault rate of 189. 2 per 100,000 residents. Akron, Ohio, in 2008 had an aggravated assault rate of 162. 4 per 100,000 residents a truly significant increase from 2007. Altoona, Pennsylvania, had an aggravated assault rate of 126. 2 per 100,000 residents, which was an excellent improvement over 2007. The reported incidents of aggravated assault have fluxgate a large amount over the years, and this can be caused by many factors to include the economy, housing, population, and increase in criminal organizations in the area. Factors leading to Crime Rates for Given Area In Altoona, Pennsylvania, the psychological effects of a poor economy may be a leading factor in the large increase in reported aggravated assault cases. The fall in the economy can greatly affect the crime rates at metropolitan cities. In Akron, Ohio, the rate of aggravated assault increased from 2007-2008, and from 2008-2009. The population only increased by 154 people from 2007-2008, and by 1018 from 2008-2009. Population growth could not be seen as a cause in the increase in reported aggravated assault cases. Akron was going through economic struggles during these time periods and again economic issues can be a large factor in increased crime rates. Lack of jobs and increase in lower income families has been shown to be leading causes of crime rate increases. References Federal Bureau of Investigation. Crime Statistics (2007). Retrieved on October 11, 2012 from http://www. fbi. gov/about-us/cjis/ucr/ucr How to cite Cja 314 Crime Data, Papers

Criminal Investigations Chapter free essay sample

In addition, Pinker created what was allied the rogues gallery which detailed the names and operations of known criminals and their associates. During the European Industrial Revolution, thief catchers (now known as informants, snitches, and a variety of other names) were hired to help law enforcement catch criminals, a practice which is obviously still In use today. In addition, thief catchers were also criminals In their own right, which made it easier to infiltrate the targeted criminals.In eighteenth century Paris, a personal identification system, known as the Brillion System, became the first yester based on the Idea that human characteristics such skeleton size and eye color were the same throughout a persons life. In the rand eighteenth century, the study of fingerprints became a popular way to identify crime suspects. They did not learn until the turn of the century that each persons fingerprints were unique and could not be changed. Scotland yard, founded In the early eighteenth century, was the model that the FBI modeled Itself after Initially.All of these are examples In which criminal investigations of today have been influenced, directly and indirectly, by the east and the progress that has been made in the time that has gone by since then. 2. Q: Discuss ways In which the media have affected our perceptions of the reality of criminal Investigation. A: As with any field outside the scope of the public arena, the medias perspective on crime investigation is almost entirely responsible for the perceptions of the general public because the media has a much larger audience.Rather than studying the topic, the general public chooses to get their Information from the media. A fantastic example of how the public gains Information about rimming investigation in particular, is known as the CSS effect. In recent years, numerous TV shows based on the roles and duties of law enforcement and crime scene Investigators have received very high ratings from their viewing audience, thereby creating a considerable amount of Interest In the field of forensic science.Of course, these shows are rarely ever based on reality, and people often form assumptions about the capacity and range of law enforcements abilities regarding investigations, and the Idea that law enforcement has virtually unlimited resources. However, In reality, law enforcement Is very Limited as to what they are able to do In comparison with the space-age type of investigation tools and techniques used on television. There is much more bureaucratic red tape, and the technologies displayed on television simply do not exist.In addition, the CSS effect gives the inaccurate Impression that every crime Is given individualized attention, and that each crime Is solved quickly using the latest In technological advances. Again, the advances used on television do not exist in the real world, and the volume of cases in the real world OFF each of them in a timely fashion. In reality, many crimes go unsolved, many take a long time to solve, and there is simply not enough time in a day to fixate each individual crime where there are so much more than need the attention of law enforcement. 3.Q: Discuss the role of the FBI and how it has changed criminal investigation over the years. A: The official role of the FBI is to protect the US from terrorist and foreign intelligence threats, to uphold and enforce laws of the US, and to provide aid and services to other law enforcement agencies. The FBI investigates crimes after hey happen, and employs numerous measures to prevent crime. In 1929, the FBI introduced the I-JAR crime report, which collects information on serious crimes reported to law enforcement. These crimes include homicide, rape, robbery, aggravated assault, burglary, larceny, theft, motor vehicle theft, and arson.Among the categories of crime investigated are terrorism, espionage, government corruption, organized crime, white collar crime, violent crimes, and major thefts. The FBI has made vast progress in the field of investigation by introducing methods of identifying suspects, such as fingerprinting. The FBI also uses expert systems, which are computer models used to profile certain types of criminals. One of them is the system used by the National Center for the Analysis of Violent Crime, which develops investigative strategies based on theories which are formed from the criminal profiles which are dependent on the findings of computer models.Many of these system specialize in one area of expertise, such blood serum analysis, counterterrorism, and so forth. One more development by the FBI which drastically hanged how it conducts investigations was the development of what are known as relational databases which have the ability to quickly and efficiently sort large quantities of records and information. The most widely known of these databases was known as Big Floyd, which the FBI used for many years.Since the creation of Big Floyd, there have been massive and unprecedented improvements to such databases to adapt to more modern problems. In 1999, the national sex offender registry, which was created as part of an upgrade of the Bis current computer systems, was introduced to the internet. Yet another system the FBI has used in its investigations is face recognition technology, called leaner, has been used to age photographs of missing children to give investigators and law enforcement of good idea of what the child would look like after all the time the child has been missing.A similar system is being used by police sketch artists to draw sketches or suspects. All of these are more are Just some of the advances and improvements made in the criminal investigations field since the creation of the FBI. 4. Q: List and discuss promising developments in criminal investigation technology hat have emerged in recent years. A: As mentioned previously, numerous computer systems exist today to aid law enforcement in investigations. These are called smart systems and relational databases.Among these systems are the national sex offender registry; leaner, which age photographs of missing children to help locate them years after theyve gone missing; the Total Information Awareness information sorting and pattern matching software to sort through numerous government and business databases in an attempt to identify suspected terror wreaths; and another promising new piece of technology is called the Combat Zones That SEE program, which is being developed for military use on foreign soil, which will build a large surveillance system by networking existing cameras from numerous popular and frequented surveillance points such as parking lots and train platforms, which send images to highly advanced computer processors which are capable of recognizing suspects by physical characteristics such as eyes, hair color, facial features, body language, etc. 5. Q: Explain the differences between proactive and reactive investiga tions. A: The differences between the two types of investigations are the same differences between proactive and reactive reasoning. Reactive investigations are those that are conducting after the commission of a crime; for example, inspecting a murder victim for fibers the killer may have left behind in an attempt to create a profile of the kind of person who committed the murder. Other parts of the reactive investigation include interviewing witnesses, and using the evidence found at the crime to at least attempt to identify and/or arrest the suspected perpetrator. Proactive investigations, n the other hand, are investigations conducted before a crime is committed because a crime has been anticipated, and the suspected perpetrator has already been identified before the crime has been committed. This is typical in sting operations, and when informants have contacted law enforcement to provide information on a crime they have received from a third party. The informant may know the suspect personally, and the suspect may have even directly stated the crime he or she was planning to commit. In some instances, such investigations likely assist in preventing heretical future crimes from occurring. 6. Q: Discuss the various types of criminal investigations.A: Among the types of investigations that criminal investigators regularly conduct are background investigations, which are used in pre-employment applicant screenings to determine whether a person is suitable and qualified for a position in which the public trust will be placed on their shoulders; Suspected violations of criminal law, which can range from something as simple as possession of illegal drugs or stolen property, to something as serious as terrorism and murder; violations f civil law, which are investigated to determine financial liability on the part of the defendant, and Vice, which is drug activity and organized crime activity. The crime scene unit provides services such as crime processing, identifying fingerprints, and forensic photos. This unit responds to serious crime scenes to find, preserve, document, and collect evidence. This unit also helps identify unknown victims, suspects, witnesses, etc. , and works closely with the detective bureau in follow up investigations, in addition to suspect location, apprehension and arrest.

APA vs MLA - Differences Between Format And Citation Style

Working on a paper and thinking which formatting style to use? Confused between APA and MLA formatting? You are at the right place!! There are five major types of academic referencing styles: APA, MLA, Chicago, Oxford and Harvard. APA and MLA citation formats are probably the most commonly used referencing styles. Quick Links 1. What is a Citation and Citation Style? 2. APA vs MLA - What are the Differences? 2.1 APA Title Page vs MLA Title Page 2.2 APA PAper Format vs MLA Paper Format 2.3 APA vs MLA Citation 2.4 APA vs MLA In-Text Citation 2.5 APA vs MLA Headings and Subheadings 2.6 APA vs MLA References 2.7 APA vs MLA Bibliography 1. What is a Citation and Citation Style? Before moving forward with APA and MLA style guides and differences between them, you need to learn what a citation and citation style is. A citation is added into the academic papers and essays to refer back to the source of information and to credit the original author. It includes the name of the author, date of publication, name of the publisher, year of publication, page number, in case of books, anthologies and journals, name of the journal, edition, DOI (Digital Object Identifier) and the online source from where the data is retrieved. A citation is important to avoid plagiarism and to add credibility to your academic work. Universally, there are three main types of citation styles: APA, MLA and Chicago. 2. APA vs MLA - What are the Differences? APA format citation is similar to MLA format in quite some things like both of them use font type and size, Times New Roman 12pt, margins are one inch all around and the paper is double spaced. However, where they have some similar aspects, there are a number of differences between them that could not be avoided. Learn and follow them completely if you do not want your teacher to minus your score. Talking about the APA vs MLA points, both of these referencing styles have different histories, originations and their purposes of development. Researchers and experts developed these referencing styles to support particular fields of study. 2.1. APA Title Page vs MLA Title Page APA style papers and essays have a separate title page that is formatted in the respective style. The main things to add in the APA citation style title page are: Running Head or Title of the page; mentioning the main idea of the paper and not the whole topic Main topic, author's name and institute's name; centered on the page, 12pt, Times New Roman font style, double spaced and without any underlines, bolds and italics 1-inch margin on all four sides MLA paper does not require any separate title page and, generally, the author's name, instructor's name, department and the date of submission are mentioned on the first page of the assignment. The paper starts immediately after these details and with a centered paper title. 2.2 APA Paper Format vs MLA Paper Format Though both the citation styles share some common traits, they do have some differences in their formats. The paper presentation in both the styles is the same as both of them have 12pt Times New Roman font size and style, 1-inch margin on all four sides of the paper and double spaced. All the paragraphs are indented and the paper must contain proper, and accordingly, incites to credit the paraphrase and direct quotes. One of the main APA and MLA differences is that in the MLA, writers add endnotes and footnotes to give additional information. In APA style paper, no footnotes are added. 2.3 APA vs MLA Citation A major APA vs MLA format characteristic is the style of referencing that is used in both of them. The references in the APA format is added in the 'References' page while the cited works in MLA are added in the 'Works Cited' page. For Hardcover Books In both APA and MLA formats, the books' authors, year of publishing, publisher and place of publishing are added, but in a different order. APA The author's last name followed by the initial of the first name and year of publication, italicized name of the book, city, state and publisher are added. James, H. (1937). The ambassadors. New York, NY: Scribner. MLA For MLA print book citation method, the last name is followed by the first name of the author, the main title of the work, city, publisher, the year of publication and print, to indicate the kind of book. Dickens, Charles. Great Expectations. New York: Dodd, Mead, 1942. Print. For Online Books Online books citation differs in the way that the online source, the web link, is added into the citation so that it is accessible afterwards also. APA The following format is followed, Porter, R. (1994). London, a social history. Retrieved from http://books.google.com MLA For MLA online book citation, the following order is followed, Bodnar, Kipp, and Jeffrey L. Cohen. The B2B Social Media Book. Google Books. N.p., n.d. Web. 20 Dec. 2012. For Books from a Database Apart from hardcovers and print versions, there are many books that are available in the databases, line websites and online publishing sites and could be accessed online. For them, link to the main database is added into the reference. APA For APA, the whole format is the same but the link of the website is added. Bloom, H. (1986). American women poets. Retrieved from http://www.infobasepublishing.com. MLA The whole format is the same except only the source, web is mentioned with the date and URL of the source. Morem, Susan. 101 Tips for Graduates. New York: Ferguson, 2005. Infobase Publishing eBooks. Web. 16 Mar. 2010. http://www.infobasepublishing.com For Websites and Blogs For most of the students, online sources are a way to go. People now prefer and rely on digital mediums than print books and other sources. To highlight more of the APA vs MLA features, we are adding how to cite your online sources here. APA For websites, only its link is added, without the date on which it was accessed, along with the author and date of publishing. Cain, K. (2012, June 29). The Negative effects of Facebook on communication. Social Media Today RSS. Retrieved from http://socialmediatoday.com For blogs and articles, follow the following structure. China, The American Press, and the State Department [Web log post]. (2013, January 3). Retrieved from Schonfeld, E. (2010, May 3). MLA One core difference that we would like to mention and add in this APA vs MLA argument is that where APA follows separate format for websites and blogs, MLA follows the same for both. Cain, Kevin. "The Negative Effects of Facebook on Communication." Social Media Today RSS N.p., 29 June 2012. Web. 02 Jan. 2013. For Print Journals Academic journals are often used by students to learn about new trends and studies and to stay up-to-date also. When adding journals in your paper, or study, make sure that you follow proper citation guidelines to ensure its flawless structure. Our complete guide on MLA Format with sample paper and further examples will help you understand it further. APA To add citations and references for journals, add volume and issue number and page numbers along with the date of publication, the author's name and paper title. Jacoby, W. G. (1994). Public attitudes toward government spending. American Journal of Political Science, 38(2), 336-361. MLA For MLA, all the details mentioned for APA paper format will be added except that the order of mention will be different. Jacoby, William G. "Public Attitudes Toward Government Spending." American Journal of Political Science 38.2 (1994): 336-61. Print. For Online Journals Besides being available in libraries, academic journals are available online as well. If you are here to look for a guide to know about how to cite online journals, follow the following structure. APA Along with the previously mentioned details, in the online version, the link of the main website, paper tile and doi (Digital Object identifier), or the date of retrieval is added. Poiger, U. G. (1996). Rock 'n' roll, female sexuality, and the Cold War Battle over German Identities. The Journal of Modern Language, 68(3), 577. doi:10.1086/245343 MLA The date of retrieval and the title of the website are added at the end of the reference. Poiger, Uta G. "Rock 'n' Roll, Female Sexuality, and the Cold War Battle over German Identities." The Journal of Modern Language 68.3 (1996): 577. JSTOR. Web. 2 Jan. 2013. For Database Journals Apart from print and online journals that you can find for your paper's assistance, to format a paper from a database, use the following methods. APA To know the format, follow the following structure, Davis, E. (1932). New chapters in American psychological history. The Science News-Letter, 22(605), 306-307. doi: 10.2307/3907973 MLA Follow the following structure to add your citations for online academic journals. Jacoby, William G. "Public Attitudes Toward Government Spending." American Journal of Political Science 38.2 (1994): 336-61. JSTOR. Web. 23 Apr. 2010. 2.4 APA vs MLA In-text Citation Found a great quote or phrase? Great. Adding direct quotes and phrases and paraphrased content is a great way of supporting your research in social sciences. However, the added information must be cited and referenced properly. For a Single Author For APA in-text citation, the last name of the author followed by the date of publication and page number, in case of books or journals and specific parts of a study, is presented in parentheses. "Darwin's theory of evolution is flawed and inconsistent. (Shawn, 2015, p. 15)." In case the author's name is mentioned in the sentence, just add the year in front of the writer's name and the page number at the end of the sentence. Shawn (2015) argues that Darwin's evolution is flawed and inconsistent (p. 15). For MLA style, the last name of the author, followed by the page of the book or journal, if any, is presented in parenthesis. "Darwin's theory of evolution is flawed and inconsistent. (Shawn 15)." If the author's name is added to the sentence then the page number is mentioned only. Shawn (2015) argues that Darwin's evolution is flawed and inconsistent (15). For Multiple Authors In APA format, all the last names of the authors and year of publication are mentioned in the first in-text, separated by a comma and ampersand. Greenhouse effect is one of the key players in increasing global warming (Williams, Smith, Shaw, 2015). For every other subsequent in-text, only the first name is added, followed by et al and the year of publication. Global warming is affecting the environment on a large scale can be minimized by reducing our carbon footprint (Williams et al., 2015). For MLA paper citation, you do not need to add and mention all the writers in the first intext. Only the first author is mentioned while the others are cited as et al followed by the page number. By minimizing the use of plastic and non-biodegradable substances, the environmental hazards of carbon and global warming could be minimized to a large extent (Williams et al. 50). In case the authors are mentioned in the sentence, only page number will be mentioned at the end of the sentence. For Sources Without an Author Coming across a source without any author is probably the most frustrating thing for a student but it is common when you are working with digital images, movies and videos, dictionaries and encyclopedias and online web pages where authors are not mentioned. In APA, in case you do not find the author, add the first few words of the study and the year of publication. According to a new research, human cloning may be the future of human advancement ("Genetics and Genes," 2014). If you have mentioned the title of the study in the content then add the year of publication only. According to "Genetics and Genes" study (2014), human cloning may be the future of human advancement. In case of no author name in MLA citation, the name of the work is used in parentheses and quotation marks. If the title is too long, shorten the title but make sure that the words are the same as added and mentioned in the Works Cited. "From the moment you hold your baby in your arms you will never be the same. You might long for the person you were before, when you had freedom and time and nothing in particular to worry about" ("The Last Time"). For online sources, in both APA and MLA, the same format of author's name and date of publication is followed. In case nothing is mentioned, just add the title of the article, or paper. Make sure that you follow the right in-text citation style. 2.5 APA vs MLA Headings and Subheadings MLA does not follow a tightly knitted headings and subheadings system as it is mostly used by the students of literature and other social arts subjects. These subjects do not much of headings and subheadings and follow the paragraph system only. However, if you still want to divide your paper into sections, there is a suggested format for it. 1. Heading 1 1.1. Subheading 1 1.2. Subheading 2 2. Heading 2 2.1. Subheading 1 2.2. Subheading 2 This table is just for reference and to give you an idea only; you should use whatever works best for you but make sure that it is consistent throughout the paper. APA format has a well-defined headings and subheadings system; because this is followed by the scholars of scientific studies and they use headings and sections to organize their work, this format has a set guideline for sections. A usual APA format for headings and subheadings is: Level 1 Heading Level 2 Heading Level 3 Heading. Level 4 Heading. Level 5 Heading. When adding headings and subheadings in your APA style paper, consider these and follow the structure carefully. 2.6 APA vs MLA References In an APA paper or essay, the references are added at the end of the paper and under the 'References' title. The works used as references in an MLA paper are added under the 'Works Cited' title. All the citations and references are organized in alphabetical order. 2.7 APA vs MLA Bibliography None of the APA or MLA calls for bibliography as a must. They treat References and Works Cited pages as thorough references. However, if you do need to add the bibliography, follow the citation structure as prescribed by your respective paper's citation format. Still confused? It is completely normal to get confused with all these technicalities. We are here to help you with that. 5StarEssays is a professional essay writing service delivering quality and cheap research papers. We are always here to help you understand your papers in a better way and to give effective and timely answer to your 'write my essay' request. We know that you need fast, reliable and affordable help and we are here to provide you academic assistance. Place your orderand get your high-quality paper written by an expert writer.

Romeo and Juliet Tragedy Essays

Romeo and Juliet Tragedy Essays Romeo and Juliet Tragedy Paper Romeo and Juliet Tragedy Paper Essay Topic: Romeo and Juliet It is my opinion that no one person can be held responsible for the tragic deaths of the two lovers, Romeo and Juliet. Rather it is a combination of people and circumstances that contrive to form a tragic ending. Obviously, Romeo and Juliet is a tragedy, and thus has all the generic features of a tragedy; that there is a fatal flaw on the part of the main characters, in this case their passionate love at first sight for each other, Did my heart love till now? This passionate love means the two lovers cannot be separated, and their desperation to be together could be the reason for their plight. Alternatively, it could also be argued that Shakespeare built up dramatic expectation, via prophetic fallacy and short scenes accelerating to a climax, that the death was necessary as a dramatic ending. This structure can be clearly seen throughout the play as a whole as Shakespeare uses lower status characters (talking in prose) usually to speed up the pace, using riots and conflicts, whereas he uses the higher status characters (talking in verse) at balls or parties to slow down the pace and deepen the play. Therefore, due to Shakespeares deliberately convoluted plot, it is imperative to discuss each topic in turn, evaluating how and to what extent, each factor was responsible; starting with, arguably, one of the most important reasons; fate, or chance. Fate, or chance, was an accepted philosophical belief in Elizabethan England, and both were linked to astrology; the belief that you can see the future in the planets, Some consequence yet hanging in the stars! The belief that the two lovers have a preordained destiny, i. . that the two, star crossd lovers cannot change their fate, recurs frequently throughout the play. Shakespeares references to fate are, almost without exception, asides, Some consequence yet hanging in the stars, which meant that the character was talking to himself (and therefore the audience), and showed that Shakespeare really wanted to emphasise this point in the play to the onlookers. On looking through the play, I found there were far more references to fate in t he first two acts than the last ones. This may be because these references to fate are coupled with prophetic fallacies; which are used to build tension and dramatic expectation, to maintain interest in the first half and then allow the omniscient audience to see the inevitable consequences. I believe Shakespeare used fate as the classic medium to create the fall from power, another traditional feature of a tragedy, and then used the portents to allow the pair to see their unavoidable downfall. This fateful incurrence provides the struggle of the play; the lovers conflict against their, death-marked loves. As a subsection of fate, the references to chance specifically are fewer, and in a direct contrast to the references to fate, appear mainly at the culmination of the play. This lends rather well to the feeling of chaos, as chance is a much more random idea than fate, and gives the impression that anarchy is at work. This set up has also been chosen as a way of showing that there could be more than one person behind the tragic deaths. That is, Shakespeare has deliberately given the final two scenes a chaotic feel to illustrate the convoluted plot lines and the intertwining motives each character has, especially true of the Friar Lawrence. The only real reference to chance (although it can be argued it is fate at work) is the failure of Friar John to deliver the letter, I could not send it! Linked to Fate, is social pressure, during the play, Shakespeare uses social pressure as an agency for fate; i. e. a way to focus the situation and explaining why the lovers cannot be together. It can be argued that this is the most important reason as without a conflict and inhibitor there would be no play as Romeo and Juliet could just be together. However, social pressure is a more modern idea and as such it is unlikely that Shakespeare purposely decided to use it, and I feel probably thought of it is the feud; indeed it is only with hindsight that we can see its effect. Shakespeare emphasise this point like most of the others from the very beginning of the play, dog of the house of Montague, and even before that in the prologue, ancient grudge break to new mutiny. This first scene cleverly reflects Act 3 scene 1, but Shakespeare has changed the roles so that Romeo discards his pacifist views and is provoked into fire-eyed fury. When Shakespeare draws references to Italy, he may be reflecting the traditional, and rather stereotypical, view of Italians as all having private vendettas or feuds. However, to a certain extent it works as Shakespeare is using a literary technique of setting the events in a place the Elizabethan audience would not know about apart from what theyve been told. In particular, by leaving the facts uncle ar about the ancient grudge, one begins to feel that perhaps there wasnt one, or that it has escalated out f all control. This is used for dramatic irony, as it is in inverse proportion to the amount of destruction incurred by the end of the final scene, all are punished! Another reason which Shakespeare decided to introduce was the Friars own motives. He says, to Romeo, that he wants to turn your households rancour to pure love, but he seems wary to allow the lovers to wed in public and appears more intent of the joining of the two households than that the two lovers are together, for this alliance may so happy prove. I believe that Shakespeare has left this reason in deliberately to offer an alternative view, and to give more variety to the end scene. Shakespeare also displays an ulterior personality trait of the Friar as he appears reluctant to be found with the bodies and hurries from Capels monument rather than be caught, and when he is the language he uses reflects the way that he is prepared to tell all. The language he uses is direct, there are no puns and little imagery and the language is non-theological when compared to his behaviour in his cell, Benedicte! and Holy Saint Francis! which demonstrates how unwilling he is to be dishonoured. Fellow characters echo this sentiment, and Juliet exclaims, What if it be a poison which the Friar subtly hath ministered to have me dead? This statement turns out to be ironical as although the potion is not a poison, the Friars plans do culminate in her and Romeos death. The friar, himself raises an interesting point as a cause, he blames the rude will of human nature (Act 2 scene 3) and disclaims that self-centredness results in evil if it gains priority over grace. Maybe, therefore, it is only human nature to cause such sufferings. Another point, which recurs throughout the play, is the patriarchal dominance of the society which the play is set in. In this community fathers had absolute sway over their daughters and gave them away to whosoever they chose, and were offended if they refused. It could have been the fathers stubbornness that the two were unable to join. This point is linked to the idea about the pointlessness of the feud; it was the fathers as head of the families who were the main upholders of the feud, and they never mention the reason for their doing so. As Elizabethan society was so patriarchal, it would therefore have been a dramatic point that Shakespeare was making when he uses Juliets sarcasm as a device to fight back at her father, It is an honour I dream not of! In the context of this play, this means that Capulet feels it is his right to pressurise Juliet, go with Paris to Saint Peters church, Or I will drag thee on a hurdle thither. The separation between Juliet and her father is repeated in the Lady Capulet, and the two seem uneasy when together. Shakespeare demonstrates this point by splitting a technique such as repetition across the two characters, so the two appear to be interrupting each other for example, Lady Capulet: The county Paris, at Saint Peters Church Shall happily make thee a joyful bride. Juliet: Now by Saint Peters Church and Peter too, He shall not make me there a joyful bride. Such repetition increases the tightening tension of the plot and gives an additional insight into the pairs characters. My final point is perhaps the most obvious, that it is the love or passion of Romeo and Juliet themselves that causes their death. The two lovers are so madly in love that are too hasty and Shakespeare emphasises this by short scenes accelerating to an abrupt climax. It can be argued that the structure of the play therefore reflects the pairs turbulent relations as when they are harmonious the pace is slowed, and this is then sped up when the two are desperately seeking each other. Perhaps the tragic ending is Shakespeares way of rebuking both love at first sight and the artificial, chivalric love between Rosaline and Romeo. In conclusion, as can be seen from the discussed reasons; there are, as with all of Shakespeares plays a multitude of factors, which are all equally valid and viable. Also, all of Shakespeares language is intentional, so he is able to cleverly link both individual passages and whole scenes to the play as a whole. However, Shakespeare emphasises some more than others and in this respect I believe it is fate, which is the most predominantly mentioned of the factors. This is consistently mentioned by Shakespeare and lends itself to the play as a whole well. As previously discussed it lends a feeling of impending doom, and inevitable tragedy to the play. This factor could have become too linear, so Shakespeare introduced the idea of chance, which adds a random and chaotic air to the play. Also, all of Shakespeares language is intentional, so he is able to cleverly link both individual passages and whole scenes to the play as a whole.

No topic Essay Example | Topics and Well Written Essays - 500 words - 23

No topic - Essay Example Although in reality this short piece of writing encompasses and deals with some major aspects of the life of human beings such success, failures and fears. The writer begins the story with a tone of zeal for life when she talks about the long winter days where people plan their routines on hourly basis. â€Å"It never got very dark. Your life parted and opened in sunlight† (Dillard, p. 94). It implies that the writer’s life as well as the lives of her fellow human beings was a busy one where everyone was a participant in the marathon of success. However some were highly successful like Rahm who had the power to entrance and enchant people with his agility and experience while others were on a lesser level like other pilots who knew the same acrobatics but could not perform all of them at once. Since the very beginning of the story Dillard provides the readers with the comparison between the lives of successful and the lesser successful people in life which also inspires an individual to work harder and better to prosper. As it is also apparent from the antics of the blue swallow as well, â€Å"the swallow climbed high ov er the runway, held its wings oddly, tipped them†¦ the inspired swallow† (Dillard, p. 97). Dillard also explores the psychological impact of fear that leads to failure and the insecurities an individual might harbor regardless of his success and prosperity in life. â€Å"Sitting invisible at the controls of a distant plane, he became an agent and the instrument of art†¦ robed in the plane he was featureless as a priest† (Dillard, p. 110). These lines highlight that success does not make an individual perfect or invincible every person has his fair share of fears, insecurities and troubles however the intelligent ones just cover their weaknesses better than the lesser intelligent ones. Furthermore regardless of the dexterity and expertise that one might have it does not guarantee that they are

Philosophy Assignment Example | Topics and Well Written Essays - 750 words - 5

Philosophy - Assignment Example She responded with, â€Å"Being gay isn’t like trying on a pair of jeans, deciding you don’t like them, and then putting them back on the shelf. If you’re gay, you’re gay. There’s no changing that.† When I asked her if she was discriminated against for her sexual orientation, she answered with a simple yes, not going into further detail. Finally, I asked her if she would be accepting if her child started dating someone of the same sex. She said of course, and jokingly said she wouldn’t be accepting if they dated someone of the opposite sex. She went on to say that she would be supportive of whoever who child decided to date. Ashley seemed to be one of many gay people that did not seem even the slightest bit abashed to openly discuss her sexual orientation. She answered the questions with pride and dignity; she was very open in her responses and did not seem the least bit uncomfortable. She clearly feels strongly for the equality of gay people. Her response to my final question had been amusing. Even though it was said with humor, it showed a side that is seldom revealed about gay people: while heterosexual couples feel that homosexuality is odd and abnormal, the gay community often feels the same way about heterosexual couples. It was an interesting experience for me to see the two different sides of the story. Lauren is a 17 year old black female. When I asked her if gay people should be allowed to marry, she answered with, â€Å"What difference does it make if they are the same sex? Marriage is love, not gender.† I then asked if gay couples should be given full civil rights. She answered with a yes, explaining that America stands on equality and should extend the same rights to everyone, regardless of sexual orientation. I asked her if being gay was something that could be changed. Similar to Ashley, she said that she believed that people did not really have a choice, and that many people try to date the opposite sex

Critique of Kokomo sung by the Beach Boys Essay

Critique of Kokomo sung by the Beach Boys - Essay Example Mike Love added the "Aruba, Jamaica" part and changed the line "Thats where we used to go" to "Thats where we want to go."† (par. 5). The song was played in the movie Cocktail which featured Tom Cruise. It was ranked number 1 in the US Billboard Hot 100 number-one singles (DeKnock, 1988). The pitch is an element of tone, determined by the frequency of vibration (Free Dictionary, par. 1). The song was delivered in well balanced vocal tones and vibration accompanied by steel drums, acoustic guitar, bass and saxophone. The pitch of the voice of singers, Mike Love and Carl Wilson, were harmonious and well blended. The intensity or loudness was average with vocals and instrumentation concocted to arrive at a unified musical structure. High quality exudes from the distinctive overtones heard from the drums at the background and the guitar. In an article written by Jones on Understanding Vibrato, he defined vibrato as "slight variation of pitch resulting from the free oscillation of the vocal cords". This free oscillation of the vocal cords results from (1) an open pharynx or what many call the "open throat" along with (2) healthy "closure of the cords" I consider that vibrato is a result of these two opposites working together: open throat and closed cords. (3) Another majo r factor to be considered in regard to vibrato is the even sub-glottic breath pressure.

On the Implant Communication and MAC Protocols for a WBAN

On the Implant Communication and MAC Protocols for a WBAN Abstract Recent advances in micro-electro-mechanical systems (MEMS), wireless communication, low-power intelligent sensors, and semiconductor technologies have allowed the realization of a wireless body area network (WBAN). A WBAN provides unobtrusive health monitoring for a long period of time with real-time updates to the physician. It is widely used for ubiquitous healthcare, entertainment, and military applications. The implantable and wearable medical devices have several critical requirements such as power consumption, data rate, size, and low-power medium access control (MAC) protocols. This article consists of two parts: body implant communication, which is concerned with the communication to and from a human body using RF technology, and WBAN MAC protocols, which presents several low-power MAC protocols for a WBAN with useful guidelines. In body implant communication, the in-body radio frequency (RF) performance is affected considerably by the implants depth inside the human body as well as by the muscle and fat. We observe best performance at a depth of 3cm and not close to the human skin. Furthermore, the study of low-power MAC protocols highlights the most important aspects of developing a single, a low-power, and a reliable MAC protocol for a WBAN. Keywords: In-body, on-body, RF communication, Implant, WBAN 1. Introduction Cardiovascular diseases are the foremost cause of deaths in the United States and Europe since 1900. More than ten million people are affected in Europe, one million in the US, and twenty two million people in the world [1]. The number is projected to be triple by 2020, resulting in an expenditure of around 20% of the gross domestic product (GDP). The ratio is 17% in South Korea and 39% in the UK [2]. The healthcare expenditure in the US is expected to be increased from $2.9 trillion in 2009 to $4 trillion US dollars in 2015 [3]. The impending health crisis attracts researchers, industrialists, and economists towards optimal and quick health solutions. The non-intrusive and ambulatory health monitoring of patients vital signs with real time updates of medical records via internet provide economical solutions to the health care systems. A wireless body area network (WBAN) is becoming increasingly important for healthcare systems, sporting activities, and members of emergency as well as military services. WBAN is an integration of in-body (implants) and on-body (wearable) sensors that allow inexpensive, unobtrusive, and long-term health monitoring of a patient during normal daily activities for prolonged periods of time. In-body radio frequency (RF) communications have the potential to dramatically change the future of healthcare. For example, they allow an implanted pacemaker to regularly transmit performance data and the patients health status to the physician. However, the human body poses many wireless transmission challenges. This is partially conductive and consists of materials having different dielectric constants and characteristics impedance. The interface of muscles and fats may reflect the RF wave rather than transmitting it. The key elements of an RF-linked implant are the in-body antenna and the communi cation link performance. Also, in the case of many implants and wearable sensors, a low-power MAC protocol is required to accommodate the heterogeneous traffic in a power-efficient manner. This article is divided into two parts: body implant communication and WBAN MAC protocols. In the body implant communication part, we look at the RF communication link performance at various depths inside a human (artificial) body. In the MAC part, we review the existing low-power MAC protocols and discuss their pros and cons in the context of a WBAN. We further provide alternative MAC solutions for in-body and on-body communication systems. The rest of the article is divided into three sections. In section 2, we present a discussion on body implant communication including in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. Section 3 discusses several low-power MAC protocols and realizes a need for a new, a low-power, and a reliable MAC protocol for a WBAN. The final section concludes our work. 2. Body Implant Communication There are several ways to communicate with an implant that includes the use of electromagnetic induction and RF technology. Both are wireless and their use depends on the application requirements. Further, the key elements of an RF-linked implant are the in-body antenna and the communication link performance. The following part discusses in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. 2.1. In-body Electromagnetic Induction Several applications still use electromagnetic coupling to provide a communication link to an implant device. In this scheme, an external coil is held very close to the body that couples to a coil implanted just below the skin surface. The implant is powered by the coupled magnetic field and requires no battery for communication. Data is transferred from the implant by altering the impedance of the implanted loop that is detected by the external coil and electronics. This type of communication is commonly used to identify animals that have been injected with an electronic tag. Electromagnetic induction is used when continuous, long-term communication is required. The base band for electromagnetic communication is typically 13.56 MHz or 28 MHz, with other frequencies also available. The choice of a particular band is subject to regulation for maximum specific absorption rate (SAR). The inductive coupling achieves best power transfer efficiency when uses large transmit and receive coil s. It, however, becomes less efficient when the space is an issue of the device is implanted deep inside the human body. Furthermore, inductive coupling technique does not support a very high data rate and cannot initiate a communication session from inside of the body. 2.2. In-body RF Communication Compared with the electromagnetic induction, RF communication dramatically increases bandwidth and supports a two-way data communication. The band designated for the in-body RF communication is medical implant communication service (MICS) band and is around 403 to 405 MHz. This band has a power limit of 25  µW in the air and is usually split into ten channels of 300 kHz bandwidth each. The human body is a medium that poses numerous wireless transmission challenges. It consists of various components that are not predictable and will change as the patient ages, gains or losses weight, or even changes posture. Values of dielectric constant (ÃŽ µr), conductivity (ÏÆ') and characteristic impedance (Zo) for some body tissue are given in table 1 [4]. This demonstrates that these two tissue types are very different. Also, the dielectric constant affects the wavelength of a signal. At 403 MHz, the wavelength in the air is 744mm, but in muscle with ÃŽ µr = 50 the wavelength reduces to 105mm, which helps in designing implanted antennas. 2.3. In-body Antenna Design A modern in-body antenna should be tuneable by using an intelligent transceiver and software routine. This enables the antenna coupling circuit to be optimised. Due to the frequency, and available volume, a non-resonant antenna is commonly used. It has a lower gain than a resonant antenna. This makes design of the antenna coupling circuit very important. Antenna options are dictated by the location of the implant. A patch antenna can be used when the implant is flat. Patch antennas are comprised of a flat insulating substrate coated on both sides with a conductor. The substrate is a body compatible material with a platinum or a platinum/iridium conductor. The upper surface is the active face and is connected to the transceiver. The connection to the transceiver needs to pass through the case where the hermetic seal is maintained, requiring a feed-through. The feed-through must have no filter capacitors present; these are common on other devices. An implanted patch antenna is electrically larger than its physical size because it is immersed in a high (ÃŽ µr) medium. It can be much larger electrically if the substrate is of higher (ÃŽ µr), such as titania or zirconia. A loop antenna can also be attached to the implant. This antenna operates mostly by the magnetic field, whereas the patch operates mostly by the electric field. The loop antenna delivers performance comparable to that of a dipole, but with a considerably smaller size. In addition, the magnetic permeability of muscle or fat is very similar to that of an air, unlike the dielectric constant that varies considerably. This property enables an antenna to be built and used with much less need for retuning. A loop antenna can be mounted on the case in a biocompatible structure. 2.4. In-body Link Performance The demonstration system consists of a base-station, an implant, antennas, and a controlling laptop. The base-station contains a printed circuit board (PCB) with a wakeup RF circuit, a Zarlink ZL70101 IC, and a micro-controller. It sends a wakeup signal on industrial, scientific, and medical (ISM) 2.4 GHz band to power up the implant to communicate. It also supports communication within the MICS band. The implant contains a Zarlink ZL70101 IC, a micro-controller, and a battery. The power limits of the wakeup signal for ISM and MICS bands transmitters are 100mW and 25  µW respectively. Experiments that measure the performance of an implant inside a living body are difficult to arrange. The alternative is to use 3D simulation software or a body phantom defined in [5]. The use of 3D simulation software is time consuming and hence practically not valuable. Therefore, measurements are generally performed using the body phantom and immersing a battery-powered implant into it [6]. Since no additional cables are attached to the test implant, the interference errors in the measurements are minimal. The body phantom is filled with a liquid that mimics the electrical properties of the human body tissues. The test environment is an anechoic chamber that includes a screened room. The interior walls of the room have sound-absorbent cones to minimize any reflections from walls or the floor that could distort the results. In real life, however, the results will be affected by the reflections from walls, desks, and other equipment and hardware. The body phantom is mounted on a woo den stand (non-conductive). The distance from the body phantom to the base-station is 3m. The MICS base-station dipole antenna is mounted on a stand. 1(a) shows the anechoic chamber with a body phantom (on the wooden stand), a log periodic test antenna (foreground), and a base-station dipole (right). The log periodic antenna is used to calculate the power radiated from the body phantom. A depth is defined as the horizontal distance between the outer skin of the phantom and the test implant. Vertical polarization of the implant is the case when the long side of the box and the patch antenna is vertical. The link performance is measured once the communication link is established. The measurements include the effective radiated power (ERP) from the implant, the received signal at the implant from the base-station, and the link quality. Measurements are made over a set distance with all the combinations of implant and test antenna polarisations, i.e., vertical-vertical (V-V), horizontal-vertical (H-V), vertical-horizontal (V-H), and horizontal-horizontal (H-H) polarisations. Typical results are shown in 1(b) where the ERP is calculated from the received signal power and the antenna characteristics. The measurement of the signal levels is done with the log periodic antenna and the spectrum analyzer. It can be seen in the that there is a significant difference in signal levels with polarisation combinations and depths. For a V-V polarisation, the ERP increases from a 1cm depth to a maximum between 2 and 7 cm, and then it decreases. The gradual increase is due to the simulated body acti ng as a parasitic antenna. The also shows how the signal level is affected by the depth with different polarisation. Such a test needs to be done with the antenna that is to be used in the final product. To measure the received signal at the implant, the Zarlink ZL70101 has an inbuilt receive signal strength indication (RSSI) function that gives a measure of the signal level detected. RSSI is a relative measurement with no calibration. The implant receives and measures a continuous wave signal transmitted by the base-station. In this case, the implant and the base-station antennas are vertically polarised. 1(c) shows an increase in the signal level at a depth between 3 and 4cm for a 15dec power. The power settings refer to the base-station and are cond to set the ERP to 25  µW. Signal levels are not valuable unless they are related to data transmission. One way to maintain the link quality is to measure the number of times the error correction is invoked during the transmission of 100 blocks of data. Two types of error correction codes, i.e., error correction code (ECC) and cyclic redundancy code (CRC) are invoked to maintain data integrity and reliability. The fewer ECC and CRC invocations result in better link quality. In 1(d), the error correction is lowest at a depth between 3 and 5 cm. A sample of ECC data collected at a 3cm implant depth is given in Table 2. The Count indicates the number of data blocks, the Time (ms) indicates the block transmission time, and the ECC indicates the number of times it is invoked. During the transmission of 100 blocks of data at a 3cm depth, the ECC is invoked 368 times, which is further equivalent to an average 3.68 times (as given in 1(d)). 2.5. Discussion The ERP, RSSI, as well as the ECC and CRC plots show that the implant demonstrates the best performance at a depth between 3 and 5 cm. The depth and position of an implant is not chosen for engineering performance but for the best clinical reasons. The implant designer must be aware of the possible losses through the human body. The attenuation and the parasitic antenna effects vary from patient to patient, with the position of the implant and with the time as the patient gains, or looses weight. Therefore, these factors need to be built into the link budget. 3. WBAN MAC Protocols Some of the common objectives in a WBAN are to achieve maximum throughput, minimum delay, and to maximize the network lifetime by controlling the main sources of energy waste, i.e., collision, idle listening, overhearing, and control packet overhead. A collision occurs when more than one packet transmits data at the same time. The collided packets have to be retransmitted, which consumes extra energy. The second source of energy waste is idle listening, meaning that a node listens to an idle channel to receive data. The third source is overhearing, i.e., to receive packets that are destined to other nodes. The last source is control packet overhead, meaning that control information area added to the payload. Minimal number of control packets should be used for data transmission. Generally MAC protocols are grouped into contention-based and schedule-based MAC protocols. In contention-based MAC protocols such as carrier sense multiple access/collision avoidance (CSMA/CA) protocols, nodes contend for the channel to transmit data. If the channel is busy, the node defers its transmission until it becomes idle. These protocols are scalable with no strict time synchronization constraint. However, they incur significant protocol overhead. In schedule-based protocols such as time division multiple access (TDMA) protocols, the channel is divided into time slots of fixed or variable duration. These slots are assigned to nodes and each node transmits during its slot period. These protocols are energy conserving protocols. Since the duty cycle of radio is reduced, there is no contention, idle listening and overhearing problems. But these protocols require frequent synchronization. Table 3 compares CSMA/CA and TDMA protocols. 3.1. WBAN MAC Requirements The most important attribute of a good MAC protocol for a WBAN is energy efficiency. In some applications, the device should support a battery life of months or years without interventions, while others may require a battery life of tens of hours due to the nature of the applications. For example, cardiac defibrillators and pacemakers should have a lifetime of more than 5 years, while swallowable camera pills have a lifetime of 12 hours. Power-efficient and flexible duty cycling techniques are required to minimize the idle listening, overhearing, packet collisions and control packet overhead. Furthermore, low duty cycle nodes should not receive frequent synchronization and control information (beacon frames) if they have no data to send or receive. The WBAN MAC should also support simultaneous operation on in-body (MICS) and on-body channels (ISM or UWB) at the same time. In other words, it should support multiple physical layer (Multi-PHYs) communication or MAC transparency. Other important factors are scalability and adaptability to changes in the network, delay, throughput, and bandwidth utilization. Changes in the network topology, the position of the human body, and the node density should be handled rapidly and successfully. The MAC protocol for a WBAN should consider the electrical properties of the human body and the diverse traffic nature of in-body and on-body nodes. For example, the data rate of in-body nodes varies, ranging from few kbps in pacemaker to several Mbps in capsular endoscope. In the following sections, we discuss proposed MAC protocols for a WBAN with useful guidelines. We also present a case study of IEEE 802.15.4, PB-TDMA, and S-MAC protocols for a WBAN using NS2 simulator. 3.2. Proposed MAC Protocols for a WBAN In this section, we study proposed MAC protocols for a WBAN followed by useful suggestions/comments. Many of the proposed MAC protocols are the extension of existing MAC protocols originally proposed for wireless sensor networks (WSNs). 3.2.1. IEEE 802.15.4 IEEE 802.15.4 has remained the main focus of many researchers during the past few years. Some of the main reasons of selecting IEEE 802.15.4 for a WBAN were low-power communication and support of low data rate WBAN applications. Nicolas et.al investigated the performance of a non-beacon IEEE 802.15.4 in [7], where low upload/download rates (mostly per hour) are considered. They concluded that the non-beacon IEEE 802.15.4 results in 10 to 15 years sensor lifetime for low data rate and asymmetric WBAN traffic. However, their work considers data transmission on the basis of periodic intervals which is not a perfect scenario in a real WBAN. Furthermore, the data rate of in-body and on-body nodes are not always low, i.e., it ranges from 10 Kbps to 10 Mbps, and hence reduces the lifetime of the sensor nodes. Li et.al studied the behavior of slotted and unslotted CSMA/CA mechanisms and concluded that the unslotted mechanism performs better than the slotted one in terms of throughput and lat ency but with high cost of power consumption [8]. Intel Corporation conducted a series of experiments to analyze the performance of IEEE 802.15.4 for a WBAN [9]. They deployed a number of Intel Mote 2 [10] nodes on chest, waist, and the right ankle. Table 4 shows the throughput at a 0dBm transmit power when a person is standing and sitting on a chair. The connection between ankle and waist cannot be established, even for a short distance of 1.5m. All other connections show favourable performance. Dave et al. studied the energy efficiency and QoS performance of IEEE 802.15.4 and IEEE 802.11e [11] MAC protocols under two generic applications: a wave-form real time stream and a real-time parameter measurement stream [12]. Table 5 shows the throughput and the Power (in mW) for both applications. The AC_BE and AC_VO represent the access categories voice and best-effort in the IEEE 802.11e. Since the IEEE 802.15.4 operates in the 2.4 GHz unlicensed band, the possibilities of interference from other devices such as IEEE 802.11 and microwave are inevitable. A series of experiments to evaluate the impact of IEEE 802.11 and microwave ovens on the IEEE 802.15.4 transmission are carried out in [13]. The authors considered XBee 802.15.4 development kit that has two XBee modules. Table 6 shows the affects of microwave oven on the XBee remote module. When the microwave oven is ON, the packet success rate and the standard deviation is degraded to 96.85% and 3.22% respectively. However, there is no loss when the XBee modules are taken 2 meters away from the microwave oven. 3.2.2. Heartbeat Driven MAC Protocol (H-MAC) A Heartbeat Driven MAC protocol (H-MAC) [14] is a TDMA-based protocol originally proposed for a star topology WBAN. The energy efficiency is improved by exploiting heartbeat rhythm information in order to synchronize the nodes. The nodes do not need to receive periodic information to perform synchronization. The heartbeat rhythm can be extracted from the sensory data and hence all the rhythms represented by peak sequences are naturally synchronized. The H-MAC protocol assigns dedicated time slots to each node to guarantee collision-free transmission. In addition, this protocol is supported by an active synchronization recovery scheme where two resynchronization schemes are implemented. Although H-MAC protocol reduces the extra energy cost required for synchronization, it does not support sporadic events. Since the TDMA slots are dedicated and not traffic adaptive, H-MAC protocol encounters low spectral/bandwidth efficiency in case of a low traffic. For example, a blood pressure node may not need a dedicated time slot while an endoscope pill may require a number of dedicated time slots when deployed in a WBAN. But the slots should be released when the endoscope pill is expelled. The heartbeat rhythm information varies depending on the patient condition. It may not reveal valid information for synchronization all the time. One of the solutions is to assign the time slots based on the nodes traffic information and to receive synchronization packets when required, i.e., when a node has data to transmit/receive. 3.2.3. Reservation-based Dynamic TDMA Protocol (DTDMA) A Reservation-based Dynamic TDMA Protocol (DTDMA) [15] is originally proposed for a normal (periodic) WBAN traffic where slots are allocated to the nodes which have buffered packets and are released to other nodes when the data transmission/reception is completed. The channel is bounded by superframe structures. Each superframe consists of a beacon used to carry control information including slot allocation information, a CFP period a configurable period used for data transmission, a CAP period a fixed period used for short command packets using slotted aloha protocol, and a configurable inactive period used to save energy. Unlike a beacon-enabled IEEE 802.15.4 superframe structure where the CAP duration is followed by CFP duration, in DTDMA protocol the CFP duration is followed by CAP duration in order to enable the nodes to send CFP traffic earlier than CAP traffic. In addition, the duration of inactive period is configurable based on the CFP slot duration. If there is no CFP t raffic, the inactive period will be increased. The DTDMA superframe structure is given in 2(a). It has been shown that for a normal (periodic) traffic, the DTDMA protocol provides more dependability in terms of low packet dropping rate and low energy consumption when compared with IEEE 802.15.4. However, it does not support emergency and on-demand traffic. Although the slot allocation based on the traffic information is a good approach, the DTDMA protocol has several limitations when considered for the MICS band. The MICS band has ten channels where each channel has 300 Kbps bandwidth. The DTDMA protocol is valid only for one channel and cannot operate on ten channels simultaneously. In addition, the DTDMA protocol does not support the channel allocation mechanism in the MICS band. This protocol can be further investigated for the MICS band by integrating the channel information in the beacon frame. The new concept may be called Frequency-based DTDMA (F-DTDMA), i.e., the coordinator first selects one of the channels in the MICS band and then divides the selected channel in TDMA superframe (s) according to the DTDMA protocol. However the FCC has imposed several restrictions on the channel selection/allocation mechanism in the MICS band, which further creates problems for the MAC designers. 3.2.4. BodyMAC Protocol A BodyMAC protocol is a TDMA-based protocol where the channel is bounded by TDMA superframe structures with downlink and uplink subframes as given in 2(b) [16]. The downlink frame is used to accommodate the on-demand traffic and the uplink frame is used to accommodate the normal traffic. There is no proper mechanism to handle the emergency traffic. The uplink frame is further divided into CAP and CFP periods. The CAP period is used to transmit small size MAC packets. The CFP period is used to transmit the normal data in a TDMA slot. The duration of the downlink and uplink superframes are defined by the coordinator. The advantage of the BodyMAC protocol is that it accommodates the on-demand traffic using the downlink subframe. However, in case of low-power implants (which should not receive beacons periodically), the coordinator has to wake up the implant first and then send synchronization packets. After synchronization, the coordinator can request/send data in the downlink subframe. The wake up procedure for low-power implants is not defined in the BodyMAC protocol. One of the solutions is to use a wakeup radio in order to wake up low-power implants before using the downlink subframe. In addition the wakeup packets can be used to carry control information such as channel (MICS band) and slot allocation information from the coordinator to the nodes. Finally, the BodyMAC protocol uses the CSMA/CA protocol in the CAP period which is not reliable for a WBAN. This should be replaced by slotted-ALOHA as done in DTDMA. Further details on low-power MAC protocols (originally proposed for WSNs) for a WBAN are given in Appendix I. 3.3. Case Study: IEEE 802.15.4, PB-TDMA, and SMAC Protocols for a WBAN In this section, we investigate the performance of a beacon-enabled IEEE 802.15.4, preamble-based TDMA [17], and SMAC protocols for an on-body communication system. Our analysis is verified by extensive simulations using NS-2. The wireless physical parameters are considered according to a low-power Nordic nRF2401 transceiver (Chipcon CC2420 radio [18] is considered in case of IEEE 802.15.4) [19]. This radio transceiver operates in the 2.4-2.5 GHz band with an optimum transmission power of -5dBm. We use the shadowing propagation model throughout the simulations. We consider a total of 7 nodes firmly placed on a human body. The nodes are connected to the coordinator in a star topology. The distribution of the nodes and the coordinator is given in 3(a). The initial nodes energy is 5 Joules. The packet size is 120 bytes. The average data transmission rate of ECG, EEG, and EMG is 10, 70, and 100 kbps. The transport agent is a user datagram protocol (UDP). Since the traffic is an uplink t raffic, the buffer size at the coordinator is considered unlimited. In a real WBAN, the buffer size should be configurable based on the application requirements. For energy calculation, we use the existing energy model defined in NS-2. The simulation area is 33 meter and each node generates constant bit rate (CBR) traffic. The CBR traffic is an ideal model for some of the medical applications, where the nodes send data based on pre-defined traffic patterns. However, most of the nodes in a WBAN have heterogeneous traffic characteristics and they generate periodic and aperiodic traffic. In this case, they will have many traffic models operating at the same time, ranging from CBR to variable bit rate (VBR). 3(b) shows the throughput of the IEEE 802.15.4, PB-TDMA, and S-MAC protocols. The performance of the IEEE 802.15.4, when cond in a beacon-enabled mode, outperforms PB-TDMA and S-MAC protocols. The efficiency of a MAC protocol depends on the traffic pattern. In this case, S-MAC protocol results poor performance because the traffic scenario that we generated is not an ideal scenario for the S-MAC. 3(c) shows the residual energy at various nodes during simulation time. When nodes finish their transmission, they go into sleep mode, as indicated by the horizontal line. The coordinator has a considerable energy loss because it always listens to the other nodes. However, the energy consumption of the coordinator is not a critical issue in a WBAN. We further analyze the residual energy at the ECG node for different transmission powers. There is a minor change in energy loss for three different transmission powers as given in 3(d). This concludes that reducing the transmission power only d oes not save energy unless supported by an efficient power management scheme. The IEEE 802.15.4 can be considered for certain on-body medical applications, but it does not achieve the level of power required for in-body nodes. It is not sufficient for high data rate medical and non-medical applications due to its limitations to 250 kbps. Furthermore, it uses slotted or unslotted CSMA/CA where the nodes are required to sense the channel before transmission. However, the channel sensing is not guaranteed in MICS band because the path loss inside the human body due to tissue heating is much higher than in free space. Bin et.al studied the clear channel assessment (CCA) range of in-body nodes which is only 0.5 meters [20]. This unreliability in CCA indicates that CSMA/CA is not an ideal technique for the in-body communication system. An alternative approach is to use a TDMA-based protocol that contains a beacon, a configurable contention access period (CCAP), and a contention free period (CFP) [21]. Unlike the IEEE 802.15.4, this protocol is required to use a slot ted-ALOHA protocol in the CCAP instead of CSMA/CA. The CCAP period should contain few slots (3 or 4) of equal duration and can be used for short data transmission and a guaranteed time slot (GTS) allocation. To enable a logical connection between the in-body and the on-body communication systems, a method called bridging function can be used as discussed in [21]. The bridging function can integrate in-body and on-body nodes into a WBAN, thus satisfying the MAC transparency requirement. Further details about bridging function are given in [22]. 3.4. Discussion Since the CSMA/CA is not suitable due to unreliable CCA and heavy collision problems, it can be seen that the most reliable power-efficient protocol is a TDMA-based protocol. Many protocols have been proposed for a WBAN and most of them are based on a TDMA-based mechanism. However, all of them have pros and cons for a real WBAN system that should operate on Multi-PHYs (MICS, ISM, and UWB) simultaneously. The MAC transparency has been a hot topic for the MAC designers since different bands have different characteristics in terms of data rate, number of channels in a particular frequency band, and data prioritization. A good MAC protocol should enable reliable operation on MICS, ISM, and UWB etc bands simultaneously. The main problems are related to MICS band due to FCC restrictions [23]. According to FCC, â€Å"Within 5 seconds prior to initiating a communications session, circuitry associated with a medical implant programmer/control transmitter must monitor the channel or channels the MICS system devices intend to occupy for a minimum of 10 milliseconds per channel.† In other words, the coordinator must perform Listen-before-talking (LBT) criteria prior to a MICS communication sessions. The implants are not allowed to On the Implant Communication and MAC Protocols for a WBAN On the Implant Communication and MAC Protocols for a WBAN Abstract Recent advances in micro-electro-mechanical systems (MEMS), wireless communication, low-power intelligent sensors, and semiconductor technologies have allowed the realization of a wireless body area network (WBAN). A WBAN provides unobtrusive health monitoring for a long period of time with real-time updates to the physician. It is widely used for ubiquitous healthcare, entertainment, and military applications. The implantable and wearable medical devices have several critical requirements such as power consumption, data rate, size, and low-power medium access control (MAC) protocols. This article consists of two parts: body implant communication, which is concerned with the communication to and from a human body using RF technology, and WBAN MAC protocols, which presents several low-power MAC protocols for a WBAN with useful guidelines. In body implant communication, the in-body radio frequency (RF) performance is affected considerably by the implants depth inside the human body as well as by the muscle and fat. We observe best performance at a depth of 3cm and not close to the human skin. Furthermore, the study of low-power MAC protocols highlights the most important aspects of developing a single, a low-power, and a reliable MAC protocol for a WBAN. Keywords: In-body, on-body, RF communication, Implant, WBAN 1. Introduction Cardiovascular diseases are the foremost cause of deaths in the United States and Europe since 1900. More than ten million people are affected in Europe, one million in the US, and twenty two million people in the world [1]. The number is projected to be triple by 2020, resulting in an expenditure of around 20% of the gross domestic product (GDP). The ratio is 17% in South Korea and 39% in the UK [2]. The healthcare expenditure in the US is expected to be increased from $2.9 trillion in 2009 to $4 trillion US dollars in 2015 [3]. The impending health crisis attracts researchers, industrialists, and economists towards optimal and quick health solutions. The non-intrusive and ambulatory health monitoring of patients vital signs with real time updates of medical records via internet provide economical solutions to the health care systems. A wireless body area network (WBAN) is becoming increasingly important for healthcare systems, sporting activities, and members of emergency as well as military services. WBAN is an integration of in-body (implants) and on-body (wearable) sensors that allow inexpensive, unobtrusive, and long-term health monitoring of a patient during normal daily activities for prolonged periods of time. In-body radio frequency (RF) communications have the potential to dramatically change the future of healthcare. For example, they allow an implanted pacemaker to regularly transmit performance data and the patients health status to the physician. However, the human body poses many wireless transmission challenges. This is partially conductive and consists of materials having different dielectric constants and characteristics impedance. The interface of muscles and fats may reflect the RF wave rather than transmitting it. The key elements of an RF-linked implant are the in-body antenna and the communi cation link performance. Also, in the case of many implants and wearable sensors, a low-power MAC protocol is required to accommodate the heterogeneous traffic in a power-efficient manner. This article is divided into two parts: body implant communication and WBAN MAC protocols. In the body implant communication part, we look at the RF communication link performance at various depths inside a human (artificial) body. In the MAC part, we review the existing low-power MAC protocols and discuss their pros and cons in the context of a WBAN. We further provide alternative MAC solutions for in-body and on-body communication systems. The rest of the article is divided into three sections. In section 2, we present a discussion on body implant communication including in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. Section 3 discusses several low-power MAC protocols and realizes a need for a new, a low-power, and a reliable MAC protocol for a WBAN. The final section concludes our work. 2. Body Implant Communication There are several ways to communicate with an implant that includes the use of electromagnetic induction and RF technology. Both are wireless and their use depends on the application requirements. Further, the key elements of an RF-linked implant are the in-body antenna and the communication link performance. The following part discusses in-body electromagnetic induction, RF communication, antenna design, and the communication link performance. 2.1. In-body Electromagnetic Induction Several applications still use electromagnetic coupling to provide a communication link to an implant device. In this scheme, an external coil is held very close to the body that couples to a coil implanted just below the skin surface. The implant is powered by the coupled magnetic field and requires no battery for communication. Data is transferred from the implant by altering the impedance of the implanted loop that is detected by the external coil and electronics. This type of communication is commonly used to identify animals that have been injected with an electronic tag. Electromagnetic induction is used when continuous, long-term communication is required. The base band for electromagnetic communication is typically 13.56 MHz or 28 MHz, with other frequencies also available. The choice of a particular band is subject to regulation for maximum specific absorption rate (SAR). The inductive coupling achieves best power transfer efficiency when uses large transmit and receive coil s. It, however, becomes less efficient when the space is an issue of the device is implanted deep inside the human body. Furthermore, inductive coupling technique does not support a very high data rate and cannot initiate a communication session from inside of the body. 2.2. In-body RF Communication Compared with the electromagnetic induction, RF communication dramatically increases bandwidth and supports a two-way data communication. The band designated for the in-body RF communication is medical implant communication service (MICS) band and is around 403 to 405 MHz. This band has a power limit of 25  µW in the air and is usually split into ten channels of 300 kHz bandwidth each. The human body is a medium that poses numerous wireless transmission challenges. It consists of various components that are not predictable and will change as the patient ages, gains or losses weight, or even changes posture. Values of dielectric constant (ÃŽ µr), conductivity (ÏÆ') and characteristic impedance (Zo) for some body tissue are given in table 1 [4]. This demonstrates that these two tissue types are very different. Also, the dielectric constant affects the wavelength of a signal. At 403 MHz, the wavelength in the air is 744mm, but in muscle with ÃŽ µr = 50 the wavelength reduces to 105mm, which helps in designing implanted antennas. 2.3. In-body Antenna Design A modern in-body antenna should be tuneable by using an intelligent transceiver and software routine. This enables the antenna coupling circuit to be optimised. Due to the frequency, and available volume, a non-resonant antenna is commonly used. It has a lower gain than a resonant antenna. This makes design of the antenna coupling circuit very important. Antenna options are dictated by the location of the implant. A patch antenna can be used when the implant is flat. Patch antennas are comprised of a flat insulating substrate coated on both sides with a conductor. The substrate is a body compatible material with a platinum or a platinum/iridium conductor. The upper surface is the active face and is connected to the transceiver. The connection to the transceiver needs to pass through the case where the hermetic seal is maintained, requiring a feed-through. The feed-through must have no filter capacitors present; these are common on other devices. An implanted patch antenna is electrically larger than its physical size because it is immersed in a high (ÃŽ µr) medium. It can be much larger electrically if the substrate is of higher (ÃŽ µr), such as titania or zirconia. A loop antenna can also be attached to the implant. This antenna operates mostly by the magnetic field, whereas the patch operates mostly by the electric field. The loop antenna delivers performance comparable to that of a dipole, but with a considerably smaller size. In addition, the magnetic permeability of muscle or fat is very similar to that of an air, unlike the dielectric constant that varies considerably. This property enables an antenna to be built and used with much less need for retuning. A loop antenna can be mounted on the case in a biocompatible structure. 2.4. In-body Link Performance The demonstration system consists of a base-station, an implant, antennas, and a controlling laptop. The base-station contains a printed circuit board (PCB) with a wakeup RF circuit, a Zarlink ZL70101 IC, and a micro-controller. It sends a wakeup signal on industrial, scientific, and medical (ISM) 2.4 GHz band to power up the implant to communicate. It also supports communication within the MICS band. The implant contains a Zarlink ZL70101 IC, a micro-controller, and a battery. The power limits of the wakeup signal for ISM and MICS bands transmitters are 100mW and 25  µW respectively. Experiments that measure the performance of an implant inside a living body are difficult to arrange. The alternative is to use 3D simulation software or a body phantom defined in [5]. The use of 3D simulation software is time consuming and hence practically not valuable. Therefore, measurements are generally performed using the body phantom and immersing a battery-powered implant into it [6]. Since no additional cables are attached to the test implant, the interference errors in the measurements are minimal. The body phantom is filled with a liquid that mimics the electrical properties of the human body tissues. The test environment is an anechoic chamber that includes a screened room. The interior walls of the room have sound-absorbent cones to minimize any reflections from walls or the floor that could distort the results. In real life, however, the results will be affected by the reflections from walls, desks, and other equipment and hardware. The body phantom is mounted on a woo den stand (non-conductive). The distance from the body phantom to the base-station is 3m. The MICS base-station dipole antenna is mounted on a stand. 1(a) shows the anechoic chamber with a body phantom (on the wooden stand), a log periodic test antenna (foreground), and a base-station dipole (right). The log periodic antenna is used to calculate the power radiated from the body phantom. A depth is defined as the horizontal distance between the outer skin of the phantom and the test implant. Vertical polarization of the implant is the case when the long side of the box and the patch antenna is vertical. The link performance is measured once the communication link is established. The measurements include the effective radiated power (ERP) from the implant, the received signal at the implant from the base-station, and the link quality. Measurements are made over a set distance with all the combinations of implant and test antenna polarisations, i.e., vertical-vertical (V-V), horizontal-vertical (H-V), vertical-horizontal (V-H), and horizontal-horizontal (H-H) polarisations. Typical results are shown in 1(b) where the ERP is calculated from the received signal power and the antenna characteristics. The measurement of the signal levels is done with the log periodic antenna and the spectrum analyzer. It can be seen in the that there is a significant difference in signal levels with polarisation combinations and depths. For a V-V polarisation, the ERP increases from a 1cm depth to a maximum between 2 and 7 cm, and then it decreases. The gradual increase is due to the simulated body acti ng as a parasitic antenna. The also shows how the signal level is affected by the depth with different polarisation. Such a test needs to be done with the antenna that is to be used in the final product. To measure the received signal at the implant, the Zarlink ZL70101 has an inbuilt receive signal strength indication (RSSI) function that gives a measure of the signal level detected. RSSI is a relative measurement with no calibration. The implant receives and measures a continuous wave signal transmitted by the base-station. In this case, the implant and the base-station antennas are vertically polarised. 1(c) shows an increase in the signal level at a depth between 3 and 4cm for a 15dec power. The power settings refer to the base-station and are cond to set the ERP to 25  µW. Signal levels are not valuable unless they are related to data transmission. One way to maintain the link quality is to measure the number of times the error correction is invoked during the transmission of 100 blocks of data. Two types of error correction codes, i.e., error correction code (ECC) and cyclic redundancy code (CRC) are invoked to maintain data integrity and reliability. The fewer ECC and CRC invocations result in better link quality. In 1(d), the error correction is lowest at a depth between 3 and 5 cm. A sample of ECC data collected at a 3cm implant depth is given in Table 2. The Count indicates the number of data blocks, the Time (ms) indicates the block transmission time, and the ECC indicates the number of times it is invoked. During the transmission of 100 blocks of data at a 3cm depth, the ECC is invoked 368 times, which is further equivalent to an average 3.68 times (as given in 1(d)). 2.5. Discussion The ERP, RSSI, as well as the ECC and CRC plots show that the implant demonstrates the best performance at a depth between 3 and 5 cm. The depth and position of an implant is not chosen for engineering performance but for the best clinical reasons. The implant designer must be aware of the possible losses through the human body. The attenuation and the parasitic antenna effects vary from patient to patient, with the position of the implant and with the time as the patient gains, or looses weight. Therefore, these factors need to be built into the link budget. 3. WBAN MAC Protocols Some of the common objectives in a WBAN are to achieve maximum throughput, minimum delay, and to maximize the network lifetime by controlling the main sources of energy waste, i.e., collision, idle listening, overhearing, and control packet overhead. A collision occurs when more than one packet transmits data at the same time. The collided packets have to be retransmitted, which consumes extra energy. The second source of energy waste is idle listening, meaning that a node listens to an idle channel to receive data. The third source is overhearing, i.e., to receive packets that are destined to other nodes. The last source is control packet overhead, meaning that control information area added to the payload. Minimal number of control packets should be used for data transmission. Generally MAC protocols are grouped into contention-based and schedule-based MAC protocols. In contention-based MAC protocols such as carrier sense multiple access/collision avoidance (CSMA/CA) protocols, nodes contend for the channel to transmit data. If the channel is busy, the node defers its transmission until it becomes idle. These protocols are scalable with no strict time synchronization constraint. However, they incur significant protocol overhead. In schedule-based protocols such as time division multiple access (TDMA) protocols, the channel is divided into time slots of fixed or variable duration. These slots are assigned to nodes and each node transmits during its slot period. These protocols are energy conserving protocols. Since the duty cycle of radio is reduced, there is no contention, idle listening and overhearing problems. But these protocols require frequent synchronization. Table 3 compares CSMA/CA and TDMA protocols. 3.1. WBAN MAC Requirements The most important attribute of a good MAC protocol for a WBAN is energy efficiency. In some applications, the device should support a battery life of months or years without interventions, while others may require a battery life of tens of hours due to the nature of the applications. For example, cardiac defibrillators and pacemakers should have a lifetime of more than 5 years, while swallowable camera pills have a lifetime of 12 hours. Power-efficient and flexible duty cycling techniques are required to minimize the idle listening, overhearing, packet collisions and control packet overhead. Furthermore, low duty cycle nodes should not receive frequent synchronization and control information (beacon frames) if they have no data to send or receive. The WBAN MAC should also support simultaneous operation on in-body (MICS) and on-body channels (ISM or UWB) at the same time. In other words, it should support multiple physical layer (Multi-PHYs) communication or MAC transparency. Other important factors are scalability and adaptability to changes in the network, delay, throughput, and bandwidth utilization. Changes in the network topology, the position of the human body, and the node density should be handled rapidly and successfully. The MAC protocol for a WBAN should consider the electrical properties of the human body and the diverse traffic nature of in-body and on-body nodes. For example, the data rate of in-body nodes varies, ranging from few kbps in pacemaker to several Mbps in capsular endoscope. In the following sections, we discuss proposed MAC protocols for a WBAN with useful guidelines. We also present a case study of IEEE 802.15.4, PB-TDMA, and S-MAC protocols for a WBAN using NS2 simulator. 3.2. Proposed MAC Protocols for a WBAN In this section, we study proposed MAC protocols for a WBAN followed by useful suggestions/comments. Many of the proposed MAC protocols are the extension of existing MAC protocols originally proposed for wireless sensor networks (WSNs). 3.2.1. IEEE 802.15.4 IEEE 802.15.4 has remained the main focus of many researchers during the past few years. Some of the main reasons of selecting IEEE 802.15.4 for a WBAN were low-power communication and support of low data rate WBAN applications. Nicolas et.al investigated the performance of a non-beacon IEEE 802.15.4 in [7], where low upload/download rates (mostly per hour) are considered. They concluded that the non-beacon IEEE 802.15.4 results in 10 to 15 years sensor lifetime for low data rate and asymmetric WBAN traffic. However, their work considers data transmission on the basis of periodic intervals which is not a perfect scenario in a real WBAN. Furthermore, the data rate of in-body and on-body nodes are not always low, i.e., it ranges from 10 Kbps to 10 Mbps, and hence reduces the lifetime of the sensor nodes. Li et.al studied the behavior of slotted and unslotted CSMA/CA mechanisms and concluded that the unslotted mechanism performs better than the slotted one in terms of throughput and lat ency but with high cost of power consumption [8]. Intel Corporation conducted a series of experiments to analyze the performance of IEEE 802.15.4 for a WBAN [9]. They deployed a number of Intel Mote 2 [10] nodes on chest, waist, and the right ankle. Table 4 shows the throughput at a 0dBm transmit power when a person is standing and sitting on a chair. The connection between ankle and waist cannot be established, even for a short distance of 1.5m. All other connections show favourable performance. Dave et al. studied the energy efficiency and QoS performance of IEEE 802.15.4 and IEEE 802.11e [11] MAC protocols under two generic applications: a wave-form real time stream and a real-time parameter measurement stream [12]. Table 5 shows the throughput and the Power (in mW) for both applications. The AC_BE and AC_VO represent the access categories voice and best-effort in the IEEE 802.11e. Since the IEEE 802.15.4 operates in the 2.4 GHz unlicensed band, the possibilities of interference from other devices such as IEEE 802.11 and microwave are inevitable. A series of experiments to evaluate the impact of IEEE 802.11 and microwave ovens on the IEEE 802.15.4 transmission are carried out in [13]. The authors considered XBee 802.15.4 development kit that has two XBee modules. Table 6 shows the affects of microwave oven on the XBee remote module. When the microwave oven is ON, the packet success rate and the standard deviation is degraded to 96.85% and 3.22% respectively. However, there is no loss when the XBee modules are taken 2 meters away from the microwave oven. 3.2.2. Heartbeat Driven MAC Protocol (H-MAC) A Heartbeat Driven MAC protocol (H-MAC) [14] is a TDMA-based protocol originally proposed for a star topology WBAN. The energy efficiency is improved by exploiting heartbeat rhythm information in order to synchronize the nodes. The nodes do not need to receive periodic information to perform synchronization. The heartbeat rhythm can be extracted from the sensory data and hence all the rhythms represented by peak sequences are naturally synchronized. The H-MAC protocol assigns dedicated time slots to each node to guarantee collision-free transmission. In addition, this protocol is supported by an active synchronization recovery scheme where two resynchronization schemes are implemented. Although H-MAC protocol reduces the extra energy cost required for synchronization, it does not support sporadic events. Since the TDMA slots are dedicated and not traffic adaptive, H-MAC protocol encounters low spectral/bandwidth efficiency in case of a low traffic. For example, a blood pressure node may not need a dedicated time slot while an endoscope pill may require a number of dedicated time slots when deployed in a WBAN. But the slots should be released when the endoscope pill is expelled. The heartbeat rhythm information varies depending on the patient condition. It may not reveal valid information for synchronization all the time. One of the solutions is to assign the time slots based on the nodes traffic information and to receive synchronization packets when required, i.e., when a node has data to transmit/receive. 3.2.3. Reservation-based Dynamic TDMA Protocol (DTDMA) A Reservation-based Dynamic TDMA Protocol (DTDMA) [15] is originally proposed for a normal (periodic) WBAN traffic where slots are allocated to the nodes which have buffered packets and are released to other nodes when the data transmission/reception is completed. The channel is bounded by superframe structures. Each superframe consists of a beacon used to carry control information including slot allocation information, a CFP period a configurable period used for data transmission, a CAP period a fixed period used for short command packets using slotted aloha protocol, and a configurable inactive period used to save energy. Unlike a beacon-enabled IEEE 802.15.4 superframe structure where the CAP duration is followed by CFP duration, in DTDMA protocol the CFP duration is followed by CAP duration in order to enable the nodes to send CFP traffic earlier than CAP traffic. In addition, the duration of inactive period is configurable based on the CFP slot duration. If there is no CFP t raffic, the inactive period will be increased. The DTDMA superframe structure is given in 2(a). It has been shown that for a normal (periodic) traffic, the DTDMA protocol provides more dependability in terms of low packet dropping rate and low energy consumption when compared with IEEE 802.15.4. However, it does not support emergency and on-demand traffic. Although the slot allocation based on the traffic information is a good approach, the DTDMA protocol has several limitations when considered for the MICS band. The MICS band has ten channels where each channel has 300 Kbps bandwidth. The DTDMA protocol is valid only for one channel and cannot operate on ten channels simultaneously. In addition, the DTDMA protocol does not support the channel allocation mechanism in the MICS band. This protocol can be further investigated for the MICS band by integrating the channel information in the beacon frame. The new concept may be called Frequency-based DTDMA (F-DTDMA), i.e., the coordinator first selects one of the channels in the MICS band and then divides the selected channel in TDMA superframe (s) according to the DTDMA protocol. However the FCC has imposed several restrictions on the channel selection/allocation mechanism in the MICS band, which further creates problems for the MAC designers. 3.2.4. BodyMAC Protocol A BodyMAC protocol is a TDMA-based protocol where the channel is bounded by TDMA superframe structures with downlink and uplink subframes as given in 2(b) [16]. The downlink frame is used to accommodate the on-demand traffic and the uplink frame is used to accommodate the normal traffic. There is no proper mechanism to handle the emergency traffic. The uplink frame is further divided into CAP and CFP periods. The CAP period is used to transmit small size MAC packets. The CFP period is used to transmit the normal data in a TDMA slot. The duration of the downlink and uplink superframes are defined by the coordinator. The advantage of the BodyMAC protocol is that it accommodates the on-demand traffic using the downlink subframe. However, in case of low-power implants (which should not receive beacons periodically), the coordinator has to wake up the implant first and then send synchronization packets. After synchronization, the coordinator can request/send data in the downlink subframe. The wake up procedure for low-power implants is not defined in the BodyMAC protocol. One of the solutions is to use a wakeup radio in order to wake up low-power implants before using the downlink subframe. In addition the wakeup packets can be used to carry control information such as channel (MICS band) and slot allocation information from the coordinator to the nodes. Finally, the BodyMAC protocol uses the CSMA/CA protocol in the CAP period which is not reliable for a WBAN. This should be replaced by slotted-ALOHA as done in DTDMA. Further details on low-power MAC protocols (originally proposed for WSNs) for a WBAN are given in Appendix I. 3.3. Case Study: IEEE 802.15.4, PB-TDMA, and SMAC Protocols for a WBAN In this section, we investigate the performance of a beacon-enabled IEEE 802.15.4, preamble-based TDMA [17], and SMAC protocols for an on-body communication system. Our analysis is verified by extensive simulations using NS-2. The wireless physical parameters are considered according to a low-power Nordic nRF2401 transceiver (Chipcon CC2420 radio [18] is considered in case of IEEE 802.15.4) [19]. This radio transceiver operates in the 2.4-2.5 GHz band with an optimum transmission power of -5dBm. We use the shadowing propagation model throughout the simulations. We consider a total of 7 nodes firmly placed on a human body. The nodes are connected to the coordinator in a star topology. The distribution of the nodes and the coordinator is given in 3(a). The initial nodes energy is 5 Joules. The packet size is 120 bytes. The average data transmission rate of ECG, EEG, and EMG is 10, 70, and 100 kbps. The transport agent is a user datagram protocol (UDP). Since the traffic is an uplink t raffic, the buffer size at the coordinator is considered unlimited. In a real WBAN, the buffer size should be configurable based on the application requirements. For energy calculation, we use the existing energy model defined in NS-2. The simulation area is 33 meter and each node generates constant bit rate (CBR) traffic. The CBR traffic is an ideal model for some of the medical applications, where the nodes send data based on pre-defined traffic patterns. However, most of the nodes in a WBAN have heterogeneous traffic characteristics and they generate periodic and aperiodic traffic. In this case, they will have many traffic models operating at the same time, ranging from CBR to variable bit rate (VBR). 3(b) shows the throughput of the IEEE 802.15.4, PB-TDMA, and S-MAC protocols. The performance of the IEEE 802.15.4, when cond in a beacon-enabled mode, outperforms PB-TDMA and S-MAC protocols. The efficiency of a MAC protocol depends on the traffic pattern. In this case, S-MAC protocol results poor performance because the traffic scenario that we generated is not an ideal scenario for the S-MAC. 3(c) shows the residual energy at various nodes during simulation time. When nodes finish their transmission, they go into sleep mode, as indicated by the horizontal line. The coordinator has a considerable energy loss because it always listens to the other nodes. However, the energy consumption of the coordinator is not a critical issue in a WBAN. We further analyze the residual energy at the ECG node for different transmission powers. There is a minor change in energy loss for three different transmission powers as given in 3(d). This concludes that reducing the transmission power only d oes not save energy unless supported by an efficient power management scheme. The IEEE 802.15.4 can be considered for certain on-body medical applications, but it does not achieve the level of power required for in-body nodes. It is not sufficient for high data rate medical and non-medical applications due to its limitations to 250 kbps. Furthermore, it uses slotted or unslotted CSMA/CA where the nodes are required to sense the channel before transmission. However, the channel sensing is not guaranteed in MICS band because the path loss inside the human body due to tissue heating is much higher than in free space. Bin et.al studied the clear channel assessment (CCA) range of in-body nodes which is only 0.5 meters [20]. This unreliability in CCA indicates that CSMA/CA is not an ideal technique for the in-body communication system. An alternative approach is to use a TDMA-based protocol that contains a beacon, a configurable contention access period (CCAP), and a contention free period (CFP) [21]. Unlike the IEEE 802.15.4, this protocol is required to use a slot ted-ALOHA protocol in the CCAP instead of CSMA/CA. The CCAP period should contain few slots (3 or 4) of equal duration and can be used for short data transmission and a guaranteed time slot (GTS) allocation. To enable a logical connection between the in-body and the on-body communication systems, a method called bridging function can be used as discussed in [21]. The bridging function can integrate in-body and on-body nodes into a WBAN, thus satisfying the MAC transparency requirement. Further details about bridging function are given in [22]. 3.4. Discussion Since the CSMA/CA is not suitable due to unreliable CCA and heavy collision problems, it can be seen that the most reliable power-efficient protocol is a TDMA-based protocol. Many protocols have been proposed for a WBAN and most of them are based on a TDMA-based mechanism. However, all of them have pros and cons for a real WBAN system that should operate on Multi-PHYs (MICS, ISM, and UWB) simultaneously. The MAC transparency has been a hot topic for the MAC designers since different bands have different characteristics in terms of data rate, number of channels in a particular frequency band, and data prioritization. A good MAC protocol should enable reliable operation on MICS, ISM, and UWB etc bands simultaneously. The main problems are related to MICS band due to FCC restrictions [23]. According to FCC, â€Å"Within 5 seconds prior to initiating a communications session, circuitry associated with a medical implant programmer/control transmitter must monitor the channel or channels the MICS system devices intend to occupy for a minimum of 10 milliseconds per channel.† In other words, the coordinator must perform Listen-before-talking (LBT) criteria prior to a MICS communication sessions. The implants are not allowed to