Inuit Art & Canadian Nationalism Essay

Inuit refers to a certain group of people who had acclimatized and inhabits the cold and harsh climatic regions of Canada. They are similar to Eskimos who live in Arctic regions of Russia and Europe and North America. Their art is a reflection of urbanization with elements of cultural experiences which denote the activities carried out within their daily life as dictated by the environment. A good Inuit art work is the one mended with vast landscape and traditional Inuit culture. Achieving such Inuit art work is sometimes challenging and controversial but it is a reflection of honest work. The Canadian Inuit art is a good example such as the one brought out by James Houston writings. James Houston was first artist to get involved in the Canadian Inuit art in 1948 with the objective of searching new land to paint. People living in the new land were very friendly, warm and the environment was vast, beautiful and cold. Interaction with the Indian and Inuit people in the Arctic provided the best opportunity for James to introduce Inuit culture to the world. Introduction of Inuit culture was made possible with the use of remarkable stories and art. There are four main particular exciting Inuit art work by James Houston in his writings. These include the White Archer, Akavak, Worlfrun and Tiktaliktak (Graburn, 2). The art work was collected in a good volume which illustrates the story about Arctic and nationalism. Many Canadian art and craft galleries, souvenir shops, and museum stores clearly confirm that tourist art is a measure of Canadian and Inuit work. Inuit art for the last say half a century has been appropriated by people living in the southern part of Canada. In addition, Inuit art is seen as one of the brightest jewels representing Canadian cultural mosaic. Inuit art is considered as one of the most important resource in establishment of Canadian identity. In many particular instances, Inuit images are viewed as symbols for identification in part or whole of the Canadian identity. Many Canadians identify themselves with Inuit art as it is one of the unquestionable means of identity. The Canadian government is usually devoted to identify between non-Aboriginal and Aboriginal peoples. The rhetorical power is used to establish a body of identifications for national identity. However, there are other indigenous images used by Canadians to represent national identity but Inuit art is the most outstanding. Indigenous art also play a very important part in identification and act as a symbol for national community identification. Organizational, individual and institutional identification needs in Canada are served through striking graphic power, prints, carvings and ability to be recognized (Maryllbelle, 1). The good graphical work creates expressive symbols for federal government. This is a clear representation of Canadian symbolism in the form of art graphics. Successive governments have tried to recognize the construction of unique Canadian identity as one of the most critical part of their mandate. For purpose of maintaining consistency, the Canadian government has tried to distinguish Canada from other countries through the use of Inuit art. A line on map could have been used to differentiate Canada from other countries but since confederation, art graphics have been in use. There are certain drawbacks in any given state that result to individual division such as ethnicity, language or religion. The use of Inuit art has no negative effects as are related to religion, language or ethnicity. Canadians have tried to differentiate themselves from U. S and other countries through the use of symbols or identity with genuine characteristics. Canadian identity has been constructed by constant shifting rhetorical identification and division process that aim at bringing communities together. It also aims at separating communities from one another as history shows how Canadians have tried to negotiate the nature of the countries core values. Identification of core values is shaped by discursive resources which were developed in the course of European settlement in Canada. Association of parties with material objects creates a marker which supports a sense of nationalism. A wide or broad group of cultural producers creates relevant material objects that interprets objects deemed fit for forming cultural equipment. Artists, dancers, painters, filmmakers, musicians, writers and sculptors play a very important part in promotion of patriotic education. This has been performed since the early twentieth century whereby material objects are provided in styles which fit the service of nationalism. In addition, societies rely on advertisers, teachers, publishers, journalists and other opinion leaders to interpret material objects. The same artists and opinion leaders disseminate the interpreted information to people with a view of constructing an appropriate conceptual linkage between material objects and national feeling (Marryllbelle, 1). The Canadian government plays a very important role in promotion of art work through incorporation of educational programs in schools and other public social gatherings. The Canadian government officially clarifies stresses and introduces appropriate pieties for material resource assortment that reflects values of country through public presentations, campaigns and internet. The use of public campaigns is to familiarize people about cultural products which help to promote art work. Canadian citizens store have their confidence in attitudes relating to resources for future reference. The retrieval of cultural attitudes arises in instances when certain national institutions try to stir up patriotic passion. Vocabularies at national levels are considered as reasons for, results of, and development of identification constructions on the basis of common interests of the citizens. The Inuit art is a reflection of Canadian language which tries to emphasis on cultural values leading to diversity of human ideas. Language is one main tool of identification which provides individuals with self worth and a sense of belonging. In the event a small group of community living within a given state loses its language, the members of the community feel left out in their identity as a cultural group. To avoid loosing identity by certain minority groups, certain commissions are formed to fight for rights of such minority communities (Stern & Stevenson, 8). Other alternative way of preserving the dignity of minority groups is through the use of art work which reflects the cultural believes of the individuals. A close look on the Canadian native art reveals that it has contributed to international exposure over the past centuries. Huge budgets have been drawn by government to support promotion of art with a view of carving out a national identity. Promotion of Eskimo art is one relative example to reflect the level at which government is in support of the Inuit art. The history of Canada showed that establishment of a national identity figure was made to promote cultural features. The desire to establish an iconic identification figure arose since the 19th century. This is a time when the Canadians wanted to establish their own identity separate from that of United States and British. After the First World War, considerations relating to public opinions changed through the efforts of seven artists (Grabaum, 1). Although they had no roots in Canada many of them were trained in Europe, their exposure and expertise into artistic work made the group of seven to travel many parts of Canada and established became one of the most sought Canadian arts. The spirit of Canada was captured in the national art and a modern style was clearly identified as suitable and had unique features reflecting Canadian culture. A large number of young artists in Canada started painting in the same vein as the seven artists. The disbursement of the seven artists group led to promotion of art work in the entire Canada. The Second World War provided a chance for Canada to establish Canadians artists (Pupchek, 7). This marked the turning point in the category of Canadian art history. Canada was very enlightened and happy with their war time military in addition to artistic efforts. This led to a revival in Canadian nationalism in various fields of art and culture which has been depicted in many journals and magazines. Nationalization of the Canadian art was a step prompted by government position to increase its support to art work. James Houston’s travel to the North gave him the chance to meet with the Inuit’s where he collected some of their art work, crafts and souvenirs. He inspired other artists who eventually started to carve small figures using soapstone which were basically used to make pots and lamps. The Inuit art was very instrumental as it was used to establish Canada as a great Northern power. The favorable image of Inuit art being products of nature, creativity of artists in ecological matters, lack of competition with mainstream art and adept at creation of materials made it possible for Inuit art to be used as a sign of Canadian national heritage.

Black Americans Essay

Firstly black Americans faced problems in the south because of lynching and the Jim Crow Laws. Lynching meant that racist white Americans would put the law into their own hands and punish black people whenever they please. They would hang the victim from a tree. In 1897 123 black people were lynched in the south, 84 in 1903 and 61 in 1921. The police would turn a blind eye and made no effort to stop lynching from happening. Even though slavery ended in 1865 black people faced the threat of violence, intimidation and racial discrimination on almost a daily bases. The Jim Crow Laws were created to keep whites and coloured people away from each other. The Jim Crow Laws covered all the aspects of life. Black Americans were stopped from using the same restaurants, hotels, libries, taxis, and even cemeteries. If black people wanted to vote the Jim Crow Law made them have to pass a difficult literacy test and they would have to pay high taxes. Nearly 2million black Americans moved from the southern states to the north in hope of a better life. This was called the Great Migration They thought they would be able to escape the Jim Crow Laws and racism as a whole, they wanted to go to the north for a better chance at jobs and education but little did they know. Secondly black Americans faced problems in the south because of the KKK. The KKK stands for the Ku Klux Klan; they were a racist group and were part of a secret society. The leader of the KKK in the 1920’s was a dentist called Hiram Wesley Evans whose name in the KKK was Imperial Wizard. Only WASP’s could belong to the KKK- White Anglo Saxon Protestants. The KKK targeted blacks mainly, but they also hated Jews, Catholics and Liberals but there main focus was poor black families that were very vulnerable. 5 million white Americans joined the KKK between 1920 to 1925. Most members where poor white people because they were afraid that black people would take over their jobs. Some of the KKK members were judges, policemen and lawyers. They would dress in white sheets and white hoods to cover their identities. The KKK used a variety of different methods such as intimidation, murders, raping, whipping, lynching, castration and tar burning. The Black Americans tried to fight back using non-violent methods. The NAACP -National Association for the Advancement of Coloured People- asked the president for new laws to help combat the KKK violence but received very little results. In the 1920’s Black Americans started to turn to the ‘Back to Africa’ movement which told blacks that they should return to their native America. This was started by Marcus Garvey but the whole movement faltered when he was arrested for fraud and sent to prison. In 1926 membership of the KKK dropped from 2million to 300,000 people. Lastly black Americans faced problems in the north because there was still racism around. Black people would be sent to live in the worst parts of the poorest cities. They were last to be hired and first to be fired from any jobs that they could get their hands on. Factory owners in northern cities knew that huge numbers of black people knew how to work well because of the slavery era. So they sent people down South to encourage them to take jobs in their factories up North with promises of good salaries. They wanted to add to the pool of white workers to keep down wages. So the black workers were encouraged to move North to compete with white workers. The white workers did not welcome the black workers with open arms because they naturally saw them as a threat. The black workers were willing to work for less money at least at first. So this led to racial tension. The white Americans refused to accept black members to protect the jobs. Another thing was that white neighbourhoods did not want poor black people and the problems that came with them moving into their neighbourhoods. It was a bad situation all around and led to much racial issues and even race riots These are the problems black people faced in the USA during the 1920s.

Cultural Norms, Fair & Lovely and Advertising Essay

2. Is it ethical to exploit cultural norms and values to promote a product? Discuss. It is ethical to utilize cultural diversity and values of a community to promote a product. However, such promotion should only be done in a way that there are not demanding to a particular group or cultural norms. Considering the case of Fair and Lovely, promoting the product using the dark and fair skin is divisive and portrays people with dark color as inferior to those with lighter color. In addition to that, the advertising identifies people with lighter color as people who have more opportunities in life, something that is likely to demean people with dark color. To this extent, the promotion is unethical. 3. Is the advertising of Fair and Lovely demeaning to women, or is it promoting the fairness cream in a way not too dissimilar from how much cosmetics are promoted? Advertising of Fair and Lovely are demeaning to women with dark color. Fair and Lovely portray women with light color as the only group that have opportunities. These advertisements offend people with dark color, considering that character, abilities, and opportunities are not defined by color. The advertisement should concentrate on its effectiveness and not describe the difference between light skin and dark people. 5. In light of AIDWA’s charges, how would you suggest Fair & Lovely promote its product? Discuss. Would your response be different if Fairever continued to use â€Å"fairness† as a theme of its promotion? Discuss. I would suggest that Fair and Lovely reconsider the cultural impact of their advertisements. AIDWA should demand that HLL answer a few questions in the respect of their issues. The questions include: Does the Fair & Lovely advertisement depict racism?

Final Essay Example | Topics and Well Written Essays - 1250 words - 9

Final - Essay Example For example, when the British and USA drones are physically present in Afghanistan, control is through satellite from USAF base outside Las Vegas, Nevada. When launched in the conflict zone, controllers carry out the operation on video screens in specially designed trailers stationed at Nevada desert. One controller ‘flies’ the drone, another operates the sensors, cameras and monitors just like a video game while the third person is in contact with the ground troops and commanders in the war zone. The CIA has been using drones in Pakistan, Afghanistan and Iraq to assassinate terrorist leaders, most notably the Al-Qaeda leader Osama Bin Laden. At least 36 American armed UAVS are present over Afghanistan and Iraq airspaces at any particular time. Many people have confused the non-flying robots for drones thereby further confusing their benefits and liabilities. Drones have several benefits among them Safety; they have greatly reduced military casualties since they carry no one. They are also significantly cheaper to purchase, fuel, operate and maintain than regular airplanes. Drones carry less risk to the military hardware since they are smaller and can fly much lower than the traditional airplanes. They have longer operational hours without fatigue since they have no human pilots. Besides, drone pilots or operators can easily hand off drone controls without any operational downtime (Collard, 2013). They are very accurate with pinpoint accuracy over great distances thus reducing collateral damage to infrastructure and civilians. Drones are also very lethal to enemy combats than regular airplanes. They have greatly increased surveillance process, reconnaissance, and general military intelligence through spying. Lastly, they a re easier and faster to deploy than most of the military alternatives. Some of the liabilities of drones include limited abilities since they cannot communicate with civilians for detailed

Analysis of Digital Mapping Assignment Example | Topics and Well Written Essays - 2250 words

Analysis of Digital Mapping - Assignment Example This method of cylindrical projection was invented in order to overcome the shortcomings of the Mercator projection method. the Peters Gall method was developed by German historian Dr. Arno Peters and British clergyman James Gall in 1973. This method was developed particularly in order to rectify the errors in area representation of countries. this method makes use of the equal-area map concept which shows areas more precisely. as compared to the Mercator projection, the area between the latitudes lines near the poles does not increase in the Peter gall projection method. this assists in decreasing the area distortion of the Mercator projection method. this projection method developed by Peter and gall received many recommendations from various organizations involved in the development of third world countries as it helped them inefficient resource allocation based on areas. however, in spite of its improvements as compared to the Mercator projection method, peter gall method also ha s significant drawbacks. the projection is unable to accurately show the shape of continents and the shapes of continents are distorted as longer or thinner in the peter gall projections. also, the peter gall projection method suffered from extreme distortions in the pole regions which was normal for any cylindrical projection method. as a result of these shortcomings, the method was not used widely in maps.   in equal in size to  Brazil, which  is 5 times larger than Alaska.      Peters Gall Projection This method of cylindrical projection was invented in order to overcome the shortcomings of the Mercator projection method. the Peters Gall method was developed by German historian Dr. Arno Peters and British clergyman James Gall in 1973. This method was developed particularly in order to rectify the errors in area representation of countries. this method makes use of the equal-area map concept which shows areas more precisely. as compared to the Mercator projection, the area between the latitudes lines near the poles does not increase in the Peter gall projection method.   this assists in decreasing the area distortion of the  Mercator  projection method. this projection method developed by Peter and gall received many recommendations from various  organizations  involved in the development of  third  world  countries as it helped them inefficient  resource alloca tion based on areas.  however,  in spite  of its improvements as compared to the  Mercator  projection method, peter gall method also has  significant  drawbacks.  Ã‚  

WALES Essay Example | Topics and Well Written Essays - 1500 words

WALES - Essay Example According to the BBC report dated 14 Nov 2012, Wales had an employment rate of 8.2% in November 2012 whereas the rate was 7.8% in the case of the whole UK for the same period. Deprivation index: - while analyzing the Wales’ deprivation index 2012, it seems that the country has satisfactory living conditions. Wales as a Tourist Destination According to BBC report dated Sep19, 2012, Wales is a rapidly emerging tourist destination in the United Kingdom with an annual industry turnover of ?3.5 billion. Statistical reports indicate that 8,078,900 people visited National Trust and Welsh Tourist Board destinations in 2002 (Wales Information, n.d.). Tourism industry plays a key role in boosting the economic growth of the Wales. To illustrate, in 2005 the tourism industry supported the economy of Wales by providing more than 100,000 service sector jobs which accounted for the country’s 8% of the workforce (ibid). The major tourist activities in Wales are mountain hiking; visitin g historic places, museums, and galleries; and shopping. Another report indicates that foreign tourists made over 1.1 million trips to Wales in 2006 (Countryside Council for Wales). Mainly, overseas tourists to Wales are from Republic of Ireland, Germany, and the United States. According to statistical information, tourism-related employment in Wales increased from 59,000 in 2000 to 78,000 in 2007 (Cultural tourism, 2012). Cardiff, the capital of the Wales, is the most popular tourist destination in the country. As Alford (2010) reports, the Cardiff tourism sector provides over 26,300 jobs and it had 14.6 million visitors in 2009. In 2004, the three cities, in term of tourists spent the most money, were Cardiff, Conwy, and Gwynedd. Wales offers improved accommodation and leisure amenities to visitors. Successes and Weaknesses While analyzing Wales’ tourism sector, it is clear that the country’s history and distinctive culture, natural environment, and attractive scener y and heritage significantly contribute to its success. The Museum of Welsh Life is the most popular tourist attraction in the country, attracting more than 600,000 tourists annually (Wales vacation packages). In addition, many castles like Caernarfon Castle and Caerphilly Castle attract visitors having historical interests. The varied landscape is another major tourist attraction in Wales. The country has three national parks including the Snowdonia National Park, the Pembrokeshire Coast National Park, and the Brecon Beacons National Park. Wales is prominent for its extreme sports activities like downhill cycling, surfing, and hang gliding. The Wales Rally GB is organized in the country annually. It has been estimated that nearly 1.8 million US citizens have Welsh ancestral roots (webarchieve.com). Hence, genealogy is major reason why many US citizens visit Wales each year. Well developed infrastructure is another reason making Wales one of the world’s popular tourist destin ations. The country has also developed improved road, rail, and air travel facilities, which are crucial to the success of the tourism industry. Wales’ proximity to all other UK markets contributes to the success of the Wales tourism industry. The country can offer a wide range of leisure activities including walking, mountaineering, and fishing (Sports and leisure activities in Wales). Wales Tourist Board (WTB) is a well established and financially sound entity.

The Progress of Women in Pakistan Essay Example | Topics and Well Written Essays - 2000 words

The Progress of Women in Pakistan - Essay Example Muslim reformers like Sir Syed Ahmed tried their best to educate the Muslim women of the subcontinent (Virdee). There were a lot of hurdles for women, imposed by the society, and attainment of education in the sub-continent was not an easy task for women of that time. Many women participated in public rallies during the Pakistan movement and women leaders took active part in the movement along with the wives of the Muslim leaders. After independence, Mohtarma Fatima Jinnah became a symbol of inspiration for the Pakistani women. She was the sister of Muhammad Ali Jinnah, the founder of Pakistan, and was very politically as well as socially active. The provision of reserved seats for women existed all through the constitutional history of Pakistan. They had the right of suffrage from independence (D. S. Ahmed 32-42). But the quota was, at the beginning, almost negligible. The progress of women in Pakistan suffered a great set back in the 1980’s, during the dictatorship of Zia-ul -Haq. He formulated and imposed oppressive laws that ran counter to the true spirit of Islam as he introduced his own radical extremist approach to Islam. On the other hand, this dark period for the women of the country was followed by the election of the first woman to be the prime minister of an Islamic state; Benazir Bhutto which was a big achievement for a woman belonging to a predominantly patriarchal society. Another major hurdle in the way of the progress of Pakistani women has been, and still is to this day, the strong feudal system. Women are still seen as objects of use, or rather misuse in feudally administered areas. Statistics show that violence against women is the greatest in these areas. This first decade of the 21st century saw the condition of women in Pakistan improve significantly, with inductions of ladies being carried out in all three armed forces in operational capacity. The proportion of women in the parliament has seen sizeable increase compared to the yest eryears. Women have access to equal education and are being inducted in all fields on equal pays. But the patriarchal mindset has not subsided, and women face discrimination and gender based prejudice and harassment in the workplaces. EFFECTS OF THE LEGAL SYSTEM The constitution of Pakistan is mostly based on the principles of Islam. In its true essence, Islam is a very moderate religion that gave women the right to suffrage and inheritance when the west was still in the dark ages. The much debated ‘Hadood Ordinance’ is a section of the law that deals largely with the punishments regarding limitations imposed on men and women individually and together. Some of the clauses are a distortion of the true limitations present in the Holy book of the Muslims; the Quran. The requirement of four witnesses to prove a woman’s claim that she had been sexually molested raised a storm of protest and criticism by the more sane minded people of the civil society (Khan 34). The l aw said that a woman could be held guilty of adultery herself if she fails to produce 4 male witnesses. This law was amended under the women protection bill of 2006 under the orders of Pervez Musharraf (Prisoners".). The women protection bill came under a lot of scrutiny from the radical religious factions who charged Musharraf with meddling with

How to Make 1000 pounds a profitable Investment in UK Stock Market Essay

How to Make 1000 pounds a profitable Investment in UK Stock Market - Essay Example b. Acting on rumours knowing that it is in fact a rumour. c. Buying Dividends for long-term investment in stock market. It is a stable and less risky way of earning profit. d. Opening an account with a broker. e. Investing in Penny stock to earn profit. Method 1 Basic Plan: The first method is to look for companies that have undervalued ratings. This method does have it perks considering that undervalued firms have a lot of value, of which general public is unaware, due to rating agencies (Graham, 1985). Now the first scenario is an investor having ?1000 and he or she has to make money through investing it in stocks looking for undervalued companies. The first reasonable thing that the investor should do is to look into companies, which have the least value on the FTSE index. For example, the investor comes up with four companies, whose stock value is ?2, ?3, ?3.50 and 3.75. Initially, I will analyse why that particular company is undervalued, does that company have large debts that it needs to pay, or the company has a record of bad investments or if the company was indicted in law-suits involving fraud etc. If the company has large debts, the investor shall see the prospects of that company paying off the debt while pragmatically and logically calculating, the duration in which the company will be able to pay its debt. If the investor wants to earn the money quickly i.e., in a week and he or she is able to find a company that can pay off its debt in two weeks, it would be best to buy stock of that company. And if the prospects of paying debt are low, the investor shall not invest in that company because of the obvious downfall state of the company. One thing that shall be kept in mind that, one must not sell all the shares if there is a slight rise in stocks because of the thought about, being on the safe side. One must project a slight confidence by observing the attitude of the market towards that company if that attitude is confident towards it then thereà ¢â‚¬â„¢s no need to sell the price and if the attitude contains lack of confidence, then one must sell shares at the price offered as earliest as possible, if one wants to liquidize stocks instantaneously. Another way is to invest it, in two or more companies at a time. The approach shall be the same as above and the reason to invest in two or more companies at a time; is unreliability in any one company. It’s just an alternative because companies are being kept undervalued for specific reasons. Sometimes the reason is right and justified in view of the person who wants to invest, but not always. This is a good way to earn money, but the chances of earning money quickly are very bleak. Drawbacks: The biggest risk involved in this kind of investment is, in case undervalued company gets further devalued because in such cases the value of stocks further decrease, resulting in loss for the shareholders. Another drawback of this plan is lack of experience of the investor who is in vesting the amount of ?1000, which is a high value. It is very important that a person should be an experienced investor person while investing because then there might be rational discussion taking place instead of decisions made on gut feeling. Another risk here is of fraud and being conned, which is very common for new investors. A new investor might get caught because of his or her

Imperialism was always seen as positive for Westerners, but as Essay

Imperialism was always seen as positive for Westerners, but as destructive by the peoples of Africa and Asia. To what extent does this statement appear to be true - Essay Example This was a major step by these countries in the west but to the subjects, i.e. Africa and Asia, this was a bad dream if not a nightmare. Africa was specifically chosen because in Africa, declining empires and wars among the locals left many states vulnerable. Furthermore, it would make available of the raw materials e.g. rubber and tin not locally available in the region and would also create a ready market for the goods. The force of European commerce, culture and power in Asia resulted to a rise to growing trade in goods/commodities that were a key development in modern world free market economy. The motives of this imperialism which were accomplished by the end of the 19th century were improving communications, medical advances, and military technologies. By 1860, Africa was still developing internally on its own terms. The dynamism and importance of Africa on the global continuum supports the theory that Africa would have evolved/developed and sustained level of advancement/devel opment and civilization without the contact with imperial forces. Also, many states had been weakened by slave trade1. On one hand, the imperialism was damaging as it led to large portions of Africa came under European colonial rule. When the imperialists saw how divided and uncivilized the local people were, they thought that with a little help they can easily conquer and rule the land. Another factor that enhanced their morale was the primitive weapons used by Africans and also they took advantage of the hospitality of the local people. This style is called ‘divide and rule . Westerners sought to fight African tribes among themselves which made it easier for them to take control and earn the ‘free’ land. Another damaging factor was famines that resulted in regions where farmers grew cash crops for export for imperialistic nations instead of food for local use. Indigenous people lost

Veteran's Affair Services Research Paper Example | Topics and Well Written Essays - 2000 words

Veteran's Affair Services - Research Paper Example Veteran’s Affair Services When one hears the term ‘veteran’, a perception of its meaning encompasses regular definitions found in the dictionaries, to wit: â€Å"a person who is long experienced or practiced in an activity or capacity† (The Free Dictionary, 2011, par. 1); â€Å"an old soldier of long service or a former member of the armed forces† (Merriam-Webster, 2011, par. 1). In contrast, the Federal definition the term is explicitly stated as â€Å"any person, who served honorably on active duty in the armed forces of the United States† (Veterans’ Agent, 2011, par. 1). These definitions confer that a veteran is a person who has rendered particularly long service, as honorably classified, in the armed forces, not only in the United States, but in other governments as well. ... In this regard, the main purpose of the research is to proffer a study of how Veteran's services affects criminal justice in the United States. Particularly, the objectives of the research are as follows: (1) to present a detailed history of the creation of Veteran’s Affair; (2) to provide a presentation of the mission statement of the social agency; (3) to present financial reports or summaries of the operations of the social agency; (4) to proffer a critical analysis of the effectiveness of the social agency, which includes, but is not limited to: details on how the specific agency interacts with the Criminal Justice System, the services provided, the training of critical personnel, and the motivation of the agency to provide services; (5) to present a commentary on ways in which the social agency could improve its effectiveness towards its social goals; and finally, (6) to provide a prediction concerning the future of the social agency and its impact on the criminal justice system. Historical Background The history of Veterans Affairs (VA) in the US was traced in the year 1636 when a war existed between the Pilgrims of Plymouth Colony were at war with the Pequot Indians and a law was enacted by the Pilgrims indicating the support pledged to disabled soldiers (US Dept. of Veterans Affairs: History, 2010, par. 1). The following historical details are presented in tabular form for concise structural arrangement, and sourced from the Dept of VA: History (2010): DATE SIGNIFICANT EVENTS 1776 During the Revolutionary War, Continental Congress encouraged enlistment of soldiers through the provision of pensions to disabled soldiers. 1811 The Federal Government authorized the first domiciliary

External envelope (consruction technolgy and materials) Essay

External envelope (consruction technolgy and materials) - Essay Example Facilitation of roadmap meetings and documentation has been performed by the department of energy's office of building technology, state and community programs (BTS) which manages the largest buildings RD& D program in the federal government. By joining forces to implement this technology roadmap, leaders in industry are laying the groundwork for residential housing that is increasingly adaptable, durable, energy and resource efficient, comfortable, and supportive of health and well-being. Modern's methods of constructions are giving architects and specify a great freedom in design that ever before. As well as the new commonly used timer frame and brick and block, insulating concrete forms (ICFs) are raising their profile in the industry. Becoming a viable alternative in providing speedy installation, and satisfaction insulation legislation. Having being used extensively in the U.S. and Canada for over 30 years, companies such as Polysteel are now developing their use in the U.K. projects such as the sovereign Harbor development in East Bourne are taking advantage of ICF's fast track construction. Inclusive design is the only guaranteed method of ensuring that a building is suitable for all disabled people who wish to use it. Inclusive design is about the specification of the building, about the intent to make it suitable for everyone to use. It blends the natural flow of the building in a way that takes account of the requirement of all groups disabled inclusive. U.K BUILDING REGULATIONS The approved document, part M of the U.K.'s building regulations gives some explanation of the reasons for each of its requirements it is in this section of the document that designers and spacefarers can see how to create an interesting building, one that will still satisfy the need of all, including disabled people, according to building products magazine.. In recent years the government has been making "all the right noise" on the environment. There is no doubt that the U.K. is one of the nations leading the way aware of the long-term consequences for us all. I will state here that if we drastically reduce the amount of Co2 emissions this country currently generate, we will contribute to the well being of the entire planet. However, there are three basic measures to be taken: better insulation for our properties making them less reliant on heating; making better use of what nature can offer in terms of wind, ware and solar energy, and most importantly, get our domestic and commercial heating systems running more efficiently. Part L of the building regulations in England and Wales has been a stipulation that boilers fitted into new properties are of the high efficiency type, with the resultant reduction in consumption of gas. According to Stephen Magdalena "over the years, architectural recast concrete cladding panels have built track records of meeting essential client requirements in a wide range of application.." MATERIAL UTILIZATIONS Of course the decision to prefabricate must be taken early and the specialist full advantage is to be gained. The range of caddy finishes available can be split into two groups: those where the actual concrete in on view and those where the concrete forms a backing to other materials. In all cases, quality is guaranteed

Experience of the readers Essay Example for Free

Experience of the readers Essay I have always looked up to my fathers good qualities and he was able to guide me in developing my interest in Economics. I have discovered that Economics have a wide range of topics and one of them would be dealing with people through Social Science. The scope it covers would range from analysis of figures to human relations and interaction. In order to fully understand this topic, skills and critical thinking should be integrated with important knowledge and logic. I view Economics in a fascinating way since I look at problems as challenges that are both innovative and worthwhile as I device solutions through the scientific method. I find joy in dealing with complicated problems since the task of using the mind as a tool is a very good way to express my interests. I believe that no matter how hard a problem is, there is a solution that can be formulated in order to compensate for insufficiencies. Though economics is a complicated field composed of many factors and variables, I view it as one would see through a kaleidoscopic where in the images viewed are beautiful pictures that exhibit complication yet there are qualities of beauty and art. Economics is an art in itself where in it works to ease the burden of the population through proper allocation of resources and other means. I believe in the role of the economist and intend be a part of the central economy as a person dealing with problems and formulating solutions. Answer (2) The author that I enjoy the most and see as the most significant is Mark Twain. His literary work is a great tool to identify the deterrents of society through satirical social commentary as a criticism on the hypocrisy highlighting the negative quality of characters being subjected. He used his works as a way to express his grievances which makes him a tool for change for the betterment of society. The novel which served a great role during his time is The Adventures of Huckleberry Finn. It has showed the true colors of society that few dared to expose. His significant effort on this issue paved the way to the formulation of a new outlook in life. The art of the literary work of Mark Twain also shows good quality in the style and presentation which greatly enhances the experience of the readers. The style is smooth and precise in which the ideas are very accurate and depicts the real life condition of that time. The plot unfolds in a way that story is presented in a fascinating way that gives meaning and continuity with the story. It incites deep thinking that will help the readers identify the necessary reformation needed at that time. The pictures illustrated in the novel are a timeless one since new ideas can be gained every time a person repeatedly reads it. He depicts society as something in need of reformation and renewal together with the social trend that shows racial discrimination and oppression.

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