Financial Analysis Essay

It was Henning Holck-Larsen and Soren Kristian Tuobro, the two promising Danish engineers who were committed to develop the engineering capabilities in order to meet the demand for the necessary industries in India. L&T at first started its business by importing sophisticated machineries for taking up complex engineering and construction assignments which was needed in the Indian market. L&T started its business by importing sophisticated machineries for taking up complex engineering and construction assignments which was needed in the Indian market from Europe. It is now a limited company fully based on engineering, technology, and construction. L&T is India’s one of the largest and know industrial organisations with a reputation for technological excellence, high quality of products and services and strong customer orientation. They value their customers by using customer focused strategy giving them value and a world class quality. It has enabled them to attain a title of the biggest player in their market field. The L&T has attained its international presence by opening its offices in different parts of world which has helped them to attain profits and grow widely. The wide marketing and distribution network not only gives them a strong customer support but also those to attain progress with keeping in mind the protection of the environment. The company is constantly on the move for innovation in their technology which helps them to attract potential shareholders. The company takes a major attention towards the culture when working in different parts of the world, which helps them to meet the satisfaction level of its stakeholders, employees and society. The company believes in their employees by giving them freedom at work which then helps their employees to complete interesting, motivating and challenging tasks with ease. It is open to suggestion and ideas at the workplace. Hence, it has given birth to advancement and the company is at present growing on a high scale with a rapid pace while playing as a major threat to their competitors. Today, the company is therefore huge and owns major Independent companies. It holds positions of independent companies in the field of Hydrocarbon, Heavy engineering, Power, Construction, Electricals and Automations, IT, Shipping, Railway projects and many more. It has created mile stones with successful projects in other countries like Sri Lanka in terms of delivering quality power projects and becoming the largest seller of coal to China. It has also played a major role in India’s maiden moon missions. Capital Structure In terms of finance, capital structure represents the way a corporation finances its assets through the combinations of equity, debt, or hybrid securities. The capital structure of a firm is then the composition or ‘structure’ of its liabilities. It gives the overview and the standing in the market place by putting a bright light on the working style of the company.

“Ethan Frome” by Edith Wharton Essay

Naturalism is commonly understood as an extension or intensification of realism. The intensification involves the introduction of characters of a kind (Baym, 1999) A perfect example of Naturalist work is Ethan Frome by Edith Wharton. Ethan, one of the main characters in the book, is a old, deformed man who is in love with his wifes cousin. Zeena is Ethans wife who occasionally has psychological illnesses. Mattie is Zeenas cousin and is in love with Ethan. There are many examples of naturalism in Ethan Frome: the characters, their deformities, and their lowly place in society, their bad luck, and distasteful environment they lived in. Ethan Frome, a significant character in the book, is very troubled. Life hasnt been pleasant for Ethan. Through his life experiences, Naturalism has been portrayed. At the beginning of the story, the reader, from the following quote, finds out that Ethan is crippled from a smash-up:The smash-up it was—I gathered from the same informant—which, besides drawing the red gash across Ethans Fromes forehead, had so shortened and warped his right side that it cost him a visible effort to take the few steps from his buggy to the post-office window. (Wharton 4)This is a characteristic of Naturalism because the smash-up was caused by Ethans emotions. If Ethan did not have any feelings for Mattie, the smash-up would have never taken place and Ethan and Mattie would not be injured and forced to spend the rest of their lives being taken care of by Zeena. Then, the novel goes into a flashback and the whole story of Ethan Frome is told to the reader. The reader then finds out that Zeena, Ethans wife, is actually his cousin who came to Starkfield to take care of Ethans mother, and she never left after his mother passed away. Ethan and Zeena get married and they have a loveless marriage that took place because of loneliness. In the novel, it says that the marriage might not have taken place if it had not been wintertime. This is also another example of Naturalism because it was decision that was controlled by their instincts that if they did not get married, then they would have a lonely winter. Zeena becomes sick, and her cousin Mattie has to come to Starkfield and take care of the house. Ethan falls in love with Mattie, but is not able to express his feelings at first because of Zeena. Later on in the story, Ethan and Mattie discover that they love each other and that they cannot be together so they decided to commit suicide. Unfortunately, the suicide attempt was futile and Mattie and Ethan both survive. In this part of the story, Ethan and Mattie are acting on their emotions because they know that they cannot runaway together, and they also know that if they commit suicide they will never have to be apart together. Ethan and Mattie would have run away together if not for their economic conditions. Because the farm was so poor, Zeena wouldnt have sold the farm for very much and she would have to suffer if Ethan and Mattie had runaway together. Although, Ethan Frome plays a very big role in this novel, Zeena also portrays examples of naturalism. Zeenas character was portrayed to the reader as being selfish and needy. Because Zeena was not required to take care of anyone, she began to show the symptoms of sickness that Ethans mother was described to have had. And within a year of their marriage she developed the sickliness which had since made her notable even in a community rich I pathological instances. When she came to take care of his mother she had seemed to Ethan like the very genius of health, but he soon saw that he skill as a nurse had been acquired by the absorbed observation of her own symptoms.(Wharton 53)This is an example of Naturalism because Zeenas need to be required by others led her to become psychologically sick and this affected her marriage with Ethan. In the middle of the novel, Ethan and Mattie walk home together after the dance and Zeena hasnt put out the key. To the reader, this seems like it was Zeenas instinct to not put out a key because she was suspicious of the relationship between Mattie and Ethan. Soon after, Zeena goes to see a new doctor in town because of her sickness. This event gives the impression that Zeena is sick only because she wants to be recognized in society, and being sick is allowing her to be noticed by others. At the very end of the novel, Zeena recognizes that Mattie and Ethan have feelings for each other, and tries to split them apart by hiring another girl to take care of the house. However, the smash-up allowed Zeena to be needed by the handicapped Mattie and Ethan, and Zeena instant got better. These are examples of naturalism, because Zeena is acting on her instincts that that Ethan and Mattie are having an affair, and the outcome is that they try to commit suicide and fail and have to live the rest of their lives together with Zeena almost in  poverty. The decisions that the characters in Ethan Frome impact the rest of their lives. These decisions are all examples of Naturalism. Ethan decisions are based on his instinct and also his emotions of love for Mattie, and his emotion of loathe for Zeena. Zeenas, on the other hand, are based on by her instinct that Ethan and Mattie are in love with each other, her lowly status in society, and also their meager economic conditions. This book shows the reader that life should not always be controlled by instinct and emotion, but rather that it should be controlled by thoughts and adapting to the environment around you. Wharton, Edith. Simon & Schuster, 2004.

Just Questions Essay Example | Topics and Well Written Essays - 2000 words

Just Questions - Essay Example Most psychoneuroses are dependent on the failure of the personality to a find an adequate solution of this conflict, and the compromise that the person reaches is not satisfactory to him. The basal or primary dispositions develop in the childhood, and they determine the future psychic development. Therefore, the personality and its forms are actually determined by the childhood development in terms of Sex and Ego, which may distinguish between different personalities. This, therefore may serve as a key to knowing these personalities. Adler's style of life theory contends that the determining factors that mould human behaviour and development and hence personality are to gain power and ascendency against the environment. This means, in human personality, the conduct is determined by a final purpose. A person's styles of life or temperamental factors determine his behaviour. According to his theory, the style of life is an affective and cognitive representation of the existential problems that any person desired to resolve. Thus this reflects the person's reactions to his perceptions about reality and the reactions that demonstrate in the ways of coping with it. This is a manifestation of cultural adaptation through the interaction between the person and the reality. Functionally, these may be equivalent to the cognitive and psychological traits of the personality which is reflected upon the genetic inheritance. Horney's construct of the "ty... Give an example of this tyranny has affected someone's lifestyle. Horney's construct of the "tyranny of should" are well depicted in the childhood development, which in future may lead to a neurotic personality. These develop early in the development through influences from temperament and environment. The child's personality and his degree of vitality and his nature and its quality may make a child rebellious or submissive under such pressures created by parental coercion. The tyranny is created by love and intimidation, tyranny, and glorification. These create the environment of the child, and their personality will be influenced by such relationships which may alter the environment from the normal of warmth, mutual respect and consideration. From the perspective the "tyranny of should" from the parents exerts pressure on the child even up to the extent that he may start feeling that his existence is dependent upon the parental wishes. The consequences are improper or incomplete development of self-respect. The personality may become insecure, ap prehensive, isolated, and resentful. Although initially, helpless, gradually he starts coping and become manipulative. The case of a child who has a stubborn negativism and who expresses himself with temper tantrums may be considered. His coping mechanism is shutting himself from others, living in his own world, where he can resent and reject every demand made upon him by the "tyranny of should" and he makes inroads to isolation and privacy which might be the beginning of a neurosis. Q4. Consider the frames of orientation presented by Fromm. Give a specific example of behavior which constitutes a healthy frame of orientation. Give specific example of behavior which constitutes an unhealthy frame of orientation.

Second Examination Term Paper Example | Topics and Well Written Essays - 500 words

Second Examination - Term Paper Example n part or the whole quantity [UCC 2-601, 2A-509)] If Joseph rejects the goods, he may acquire the cover, cancel the contract or sue the seller in the court of law as if the seller never delivered the goods (Miller, p 274). Joseph has the right to recover damages for the accepted goods. Joseph can accept the damaged portion of his goods, hold them and inform Jack (the seller) on the breach of contract. This information would prevent the buyer from pursuing any remedy [UCC 2-607(3), 2A-516(3)]. In Jack and Joseph’s case the goods delivered are, not as promised, the extent of damages would be the difference in price between the goods during the acceptance, and the value if they would have been delivered as warranted [UCC 2-714(2), 2A-519(4)] (Miller, p 271). Joseph has the right of inspection. Joseph as the buyer has an unconditional right to vet the goods before making payment. This right allows the buyer to assess the goods before making any payments to ensure that they conform to the contracted specifications (Miller, p 272). The buyer should only make payments on goods if the goods delivered maintain their quality similar to those contracted. An opportunity for inspection is therefore a condition precedent to the right of the seller or lessor to enforce payment [UCC 2-513(1), 2A-515(1)]. In case the goods are rejected because they are not conforming, the buyer can recover the costs of inspection from the seller [UCC 2-513(2)]. Jack has a right to cancel the contract the seller has a right to rescind the contract if the buyer breach the contract [UCC 2-703(f), 2A-523(1)(a)]. The seller has to notify the buyer promptly and at this point, the seller is discharged of obligations. The buyer is not discharged of all obligations and the seller can pursue the available remedies under the UCC for breach. Jack is right to cancel the contract (Miller, p 272). Jack has the right to withhold delivery. The seller can withhold the performance of their obligations under the

Importance of Work-Life Balance Research Paper Example | Topics and Well Written Essays - 250 words

Importance of Work-Life Balance - Research Paper Example Giving the employees added benefits such as the installation of a gymnasium in the work facilities for the free use of the employees can enhance the work life balance of the staff. A third technique that can be used to improve the work life balance of employees is giving the workers extended vacation time every year. Instead of the industry standard of two weeks of vacation time, the firm can offer one month of vacation time per year. Vacations are important because people that suffer from recreation deprivation act crankier and the person becomes more critical of their co-workers (Reinhold, 2012). A few years ago I faced a tough family situation that required me to take time off work to help my family. I could not ask for vacations because a few months earlier I used up all my vacation time. I also could not afford to take an unpaid leave because I was in a tough economical situation as well. I talked to my supervisor about my problem. He told me that I was in luck because he could arrange for me to work flexible hours despite the fact that a flexible time program was not available at the firm yet. The careers paths of men and women are often different due to gender issues and the different responsibilities societies impose on genders. Women often have tougher challenges in the workplace due to family responsibilities. After pregnancy the child is highly dependent on his mother. Women typically perform more shores and have higher house responsibilities than men. During the last 30 years the role of women has changed in the workplace (Erbschloe, 2009). Society has imposed on men a higher financial responsibility over the home finances. Men consequently are expected to obtain better paying jobs which required a higher level of education. There is a lot of parity in the workplace among genders, but the glass ceiling has hurt the chances of women moving up the corporate ladder. In other parts of the world such

Design an e-Business System Essay Example | Topics and Well Written Essays - 3500 words

Design an e-Business System - Essay Example Proper communication remain essential in ensuring the minimisation of errors; hence improvement of the business process. The utilisation of an internet based system for establishing links between salesmen, customers and suppliers remains essential in improvement of the processes. The different stakeholders will access information from a central source, and share information from the same centre. This sharing can effectively improve business processes and increase the company’s market share. Objectives The main purpose of the subsystem remains ensuring quick transfer of information and sharing between various stakeholders. The system aims at improving the business process and increasing efficacy of the process of making sales and manufacturing. Improvement of these processes can result in increased sales owing to the reduced time taken in making orders and delivering supplies. The application of the system objectives can ensure the company sales increase significantly, ensuring the company achieves significant growth. Background Avitz Bike is a UK based manufacturing company which specialises in different types of bikes for different markets globally. While the company experiences a considerably good market share, stiff competition has resulted in reduced market share over the last 5 years. This reduction has been attributed to the duration taken before bikes are delivered to customers. The company relies heavily on sales made through different retailers across the United Kingdom. While the utilisation of retailers has continuously provided sufficient market-share, improvement in the selling process remains inevitable as the company seeks to increase sales. The utilisation of an E-business system seeks to ensure the company reduces the delivery time for most products. This would effectively increase the current sales volume, consequently increasing the market share. The company has adopted the E-business strategy to eliminate the lengthy supply chain, pre sent in the current strategy. Description of the business process The process of receiving orders within the business involves direct communication with retailers, through telephone, electronic data exchange of facsimile. The retailers first make contact with sales managers, to negotiate on different product prices, before making orders to the company. The orders are then subjected to a validation process, which includes verification of various order requirements as stated by the retailer. This validation process results in acceptance or rejection of the order. Following the validation of different orders, required parts can be orders to enhance the assembling of the requested bike. The customer specifications determine how the distributors deliver bikes to various retailers. When utilising process, the company does not make direct contacts with the customers making the process lengthy. The company utilises an information system developed in 1997, built on LAN with Windows NT as the client-server system. The current system contains information regarding customers, suppliers, bikes and other physical attributes of company products. Some of the information contained within the system remains available to specific departments, an aspect which causes delays. Problems and solutions in project that the company is facing The company faces a number of challenges resulting from the current business process and information systems. The biggest problem

Strategic Human Resource Management Article Example | Topics and Well Written Essays - 1000 words

Strategic Human Resource Management - Article Example Those working in firms are protected by these unions such that their wages and salaries cannot be altered by the employer at his/her own pleasure. Also, the unions ensure workers work for negotiable hours. In addition, they focuses on workers’ health and safety through negotiating for favourable working conditions (Wilkinson 2014, p. 90). Secondly, the unions represent workers to their employers. Usually, the employers engage in â€Å"collective bargaining† with the trade unions. The unionsnegotiates for workers’ rights during these meetings. Sometimes, disagreements arise, which results to industrial actions such as a strike. In order to prevent workers from negotiating individually with their employers, the trade unions give them adviceandinformation on the best ways to give their complaints and at the right time. Other functions of the unions include resolving conflicts and providing services for the union members.Some of these services include insurance schemes, pension schemes, and discounts on shopping (Wilkinson 2014, p. 99). As stated earlier, trade unions have changed their roles over the past years due to globalization, outsourcing of labour and legal constraints. The role of unions has changed recently where they not only represent workers during negotiations but also recruit new workers in case the employers dismiss them. Due to the fragmentation of the labour market, the trade unions have reduced their role of ensuring the welfare of many workers. In other words, they have shifted their focus from workers to the enterprises.They regulate the workers conditions and payments at enterprise-level unlike before when they acted with workers in fighting for labour rights. The rise of unions that are sponsored by employers have eroded the basic roles of trade unions in protecting labourforce (Wilkinson 2014, p. 100). Most firms have employed the non-union workers as a way of protecting themselves from industrial strikes.Therefore, trade

Organisational Development Essay Example | Topics and Well Written Essays - 2500 words

Organisational Development - Essay Example Obsolete technology is used. Time lag in maintaining trust and goodwill is present. Opportunities Favourable circumstances that can be a source of potential benefit for Jim’s Cleaning are as follows: After training programs, results will depict improvement in employee’s attitude and this will also result in possible new markets and strong brand loyalty by old customers. Emerging new technology from order taking to service delivery can enhance competitiveness. Expansion of business can be made in other cities as well as a result of increased customer’s awareness in cleaning services. Expansion can be made in service range as well to increase customer’s loyalty and broader range of customer needs. Threats The possible threats to Jim’s Cleaning are as follows: Low morale will result in employee turnover. Many competitors are entering the market. Development Plan In order to resolve the problem, the development process comprises of following steps: Prob lem Lack of service employee’s interpersonal attributes in Jim's Cleaning is negatively impacting customer satisfaction and their commitment to retain withntioon to Jim' 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 this company. Decreasing morale of employees is directly affecting the level of satisfaction of customers and ultimately success chart of Jim’s Cleaning. Employees in Jim’s Cleaning are not getting successful in satisfying customer to the optimum level. Henceforth customers are not spreading the awareness of Jim’s Cleaning to their friends or family. This is damaging the image of the organisation in different ways. Needs are going unfilled, word of mouth and repeated customers are declining. Ultimately, bad customer... This essay stresses that the on-going training program will help to boost our employee satisfaction. Through this training program the employees will become more confident, can upgrade their skills, can pace with the changes occurring in the organisation, can work with full potential, and can deal with changing demands and needs. The training program will result in employees who are creative, motivated, satisfied with their careers and have high morals. Training course will allow them to achieve higher customer satisfaction and responsiveness in meeting the job roles. This paper makes a conclusion that organisation development is a necessary process of improving organisation effectiveness and for achieving the desired goals. If Jim’s Cleaning concentrates on creating value in employees only, then it will be able to make a positive connection between employee satisfaction and organisation profitability. The management should recognise that employee morale, performance and overall job satisfaction is a highly important component for increased profitability. If this change is implemented in the organisation, it will definitely produce positive results. Successful execution of the plan will allow Jim’s Cleaning to constantly perpetuate this synergistic relationship. By this relationship, Jim’s Cleaning will win customer loyalty that ultimately results in increased corporate profitability. Satisfied employees are a precondition for increasing productivity, responsiveness, quality, and customer service.

Summary On Current Mnagement Ariticle Essay Example | Topics and Well Written Essays - 500 words

Summary On Current Mnagement Ariticle - Essay Example The classical model of capacity expansion is an example and is applicable in cases of definite demand with constant growth rate. These models assume growth to have a geometric or stochastic trends but Karri’s timing ratio model assumes that demand has a linear but definite growth that allows for determination of optimal capacity expansion time. According to the model, early expansion of potentials leads to surplus potentials while late expansion leads to shortage of potentials. The model for capacity optimization identifies size and fixed costs of the proposed equipment, and unit fixed cost as significant factors. It shows that early project implementation is better under minimal fixed costs, relative to contribution margin. Some of the factors may again be insignificant in the model. With an assumption that an organization’s cost structure is an indicator of its expansion project, timing potentials of entities become comparable. In addition, range for investment timing widens if contribution margin is high and yet fixed costs remain minimal. Timing ratio, under the model, is inversely proportional to timing potential. Testing the model faced the challenge of contents of organizations’ income statements. While contributing margin is significant to determination of the time ratio, some organizations’ income statements do not offer items that are used in computation of the contribution ratio. The contribution margin can however be estimated and this facilitated testing of the timing ratio model. The model and its testing identify theoretical and empirical implications. Ability to compute timing ratio from contribution margin and operating income and difficulty in comparing timing ratios are the implications of the developed information (Karri n.p.). The article relates to the managerial accounting concept of value optimization through minimizing cost and

Smallpox Article Example | Topics and Well Written Essays - 500 words

Smallpox - Article Example There was some opposition regarding terms posted for getting vaccination. Certain difficulties were encountered during the process of eradication. WHO faced serious financial difficulties and it lacked constant support from its various offices within its framework. The above bottle necks were overcome in 1970's with the help of various governments and development agencies. U.S joined hands with countries like Russia and the WHO framework to make eradication a success. The decade of 1970 played a major role in helping the eradication of small pox by conducting expanded Programme on Immunization. The smallpox eradication was then certified based on intense verification performed in the countries by a group of scientists who confirmed it in December 1979 and was acknowledged by WHO's Health Assembly in 1980. 1980 witnessed the fulfillment of the goal which was considered impossible. This was the greatest achievement of global public health in the 20th century. After the 1980's, people were free from the deadly virus. But it did not last for a longer time. WHO announced multiple deadlines in 1993, 1995 and 1999 to eradicate the remaining virus stocks. But they failed to accomplish the task in the expected deadline. In 2002 U.S saw a sudden outbreak of small pox.

Memoirs of C K Janu Against the Hegemony of the Ruling Class Essay Example for Free

Memoirs of C K Janu Against the Hegemony of the Ruling Class Essay C K Janu’s unfinished autobiography â€Å"Mother Foster: The Unfinished Story of C K Janu† which is translated by N Ravi Shankar is an eloquent testimony to her courage and her convictions. It is the recounting of her experience in her past. C K Janu is the prominent organic woman leader who managed to gain land for the tribals who were stamped under foot by the elites and the government. She is the leader of the Adivasi tribes who dedicated her youth for the betterment of the tribes. In the beginning she became a member of the communist party. Later she realised that the party cheated the tribal people and she left the party in1982. Later she organised a tribal meeting in South India in 1992 as a part of the reclamation of the land of the tribe. She incited and led the agitation by the tribal people. For this she was physically and mentally assaulted nine times by the Kerala police. In 1994 she was awarded as the best tribal social worker by the Government of Kerala. But she returned the award. She became the only Indian ambassador of India in the UN tribal conference. Even though illiterate she gave speeches in 120 countries. Later in 2001 the Government of Kerala signed an agreement with the tribal people, but did not keep it. The tribals protested against this in the land at Muthanga . This ended with a massive violence. Till now the cases are going on against her. She cooperated with national and international organisations for some time and now she spends time serving the tribes.

Towards A Self Sufficient Prison Model Criminology Essay

Towards A Self Sufficient Prison Model Criminology Essay The cost of arresting and sentencing an offender has been calculated at $150,000, with every year spent in prison costing an additional $90,000 (Prison Fellowship New Zealand, 2012). In New Zealand there are over 8,000 prisoners incarcerated, the cost of housing inmates therefore totalling up to a substantial bill for the Government and taxpayers alike. Despite the millions of dollars being infiltrated into the correctional system, recidivism rates are still relatively high, with 44 % of people being released from prison, reoffending and being re-imprisoned within a three year period (Department of Corrections, 2009). Such figures are not unique to New Zealand, with the likes of the United States and United Kingdom facing larger overheads with similarly dissatisfying results in reducing reoffending. Quite contrastingly, in Nordic countries even an imperfect comparison suggests reoffending appears far less of a problem, with the overall reoffending rate over a two year period varying from the lowest in Norway at 20% to the highest in Sweden with 30% (Kristofferson, 2010). Due to variation in measuring methods between countries, caution must be taken in comparing these figures, but that aside one other possible explanation for lower reoffending rates in Nordic countries is the progressive and unique correctional methods which have been implemented there. Centred on openness, personal growth and ecology, the common aim is not to overtly punish but to focus on the rehabilitative needs of prisoners. Inspired by the particular success of Norways self-sufficing prison Bastoy and with the goal of uncovering an alternative to the traditional closed and costly prison regimes, this paper will examine the concept of self-sufficient prisons. An investigation will be made into the history of prisons which have done or still do operate under a self-sufficient ethos and an analysis of the consequential benefits and/or potential disadvantages will be carried out. Throughout the paper in-depth consideration will also be given to any relationship which research has found to exist between a prison based on self-sufficient ideals and rehabilitation. Furthermore, in weighing up the findings reached from this investigation, the viability of self-sufficient prisons realistically operating in New Zealand will be explored and any possible limitations which could hinder their success will be acknowledged. Self-sufficient prison model When confronted with the phrase self-sufficient prison, several different interpretations can be drawn as to what exactly this entails. Firstly, from an economic perspective the term self-sufficient prison represents a prison which operates with the primary goal of counteracting its running costs and even generating profits through inmate labour and production. A prison encapsulating this understanding often runs similarly to a traditional closed prison but inmates participate in working during their sentences, rather than simply idly passing the time away in cells. An example of this type of self-sufficiency can be seen at Louisiana State Penitentiary(Angola). Formed in 1835, this prison was based around the concept of inmates working and in 1880 an 8,000 acre plantation was bought to fulfil this ideal. Today, it is the biggest maximum security prison in the United States, it also has been designed on self-sufficient principles, being said to function as a small community with a can ning factory, a dairy, a mail system, a small ranch, repair shops, and a sugar mill. Colloquially known as the farm, it is situated on 18,000 acres, with approximately 5000 inmates whom work to produce enough food to support over 11,000 people throughout five different prisons in the State. The resources which come from the land are used for the benefit of inmates and benefit the community. Prison warden Bruce Cain describes the prison today by stating we all work together. Were all one. Our resources are their resources. (Auzenne Williams, 2010, p.1). Another way to interpret prison self-sufficiency is to understand it as an environment where prisoners have the opportunity provide for themselves, within the compound of a supportive correctional facility. Although still attempting to offset financial costs, the focus of such a prison is on achieving a community like existence where inmates have an element of independence, enabling them to cook, clean, work and essentially be self-sufficient. In unison with the prisoners self-sufficiency the prison would operate sustainably through adopting environmentally friendly practices which are in harmony with nature, impacting as little possible on its surrounds. This would involve energy efficient strategies being implemented such as the use of solar panels to provide hot water and heating, water conservation, reductions in transportation fuel use and high efficiency lightning and appliances. As well as that, recycling, composting and waste reduction would be of focus. Ultimately this under standing of the phrase self-sufficient prison, can be defined as a correctional facility which seeks to reduce the human, environmental and economic costs of prison. Currently, there is only one real example of a prison operating completely in line with this understanding of prison self-sufficiency. Located in Norway, on an island in the Oslo Fiord is Bastoy prison. Designed to operate as a small self-sufficient community this prison encompasses the spirit and meaning of self-sufficiency to the fullest. It not only has one of the lowest reoffending rates in the world at 16%, but is also the most cost efficient prison in the whole of Norway (Sutter, 2012). Housing up to 115 inmates, numerous buildings spread over a rural landscape and just as in any other community there is shop, library, information office, health services, church, school, NAV (government social services), dock and ferry service all located within the prison, for the inmates use. Each day inmates at Bastoy work between the hours of 8.30 am and 3.00 pm in one of various different work units, including ; the agricultural sector, the greenhouses, the forestry unit , seed and grass p roduction, the kitchen, the shop, the maintenance unit, on the fishing boat or running the ferry. (Bastoy Prison, 2012). The work they do not only allows the prison to run self-sufficiently and earn the inmates a small wage, but it also fulfils their daily existence. Bastoy instils a sense of community, reality and independence, three aspects which are key to the rehabilitation of inmates. Other aspects which separate Bastoy from traditionally run prisons and contribute to its self-sufficient existence include an absence of intimidation and scare mongering from guards, whom are unarmed and do not wear uniforms. Instead, guards are thoroughly trained to safely and purposefully interact with prisoners and just as the prisoners do, they become part of the Bastoy community. The prison is also committed to being environmentally sustainable. It is run under human-ecological values, farming is ecological, the prison handles most of its own rubbish, there is a constant focus on minimizing CO2-emissions and the buildings are heated from solar panels or the wood they grow and process themselves (Bastoy Prison, 2012). The current Governor of the prison is extremely dedicated to the self-sufficient methods instilled on the island, even living there himself. His passion is demonstrated in this quote where he states; The prison is self-sustaining and as green as possible in terms of recycling, solar panels and using horses instead of cars. It means that the inmates have plenty to do and plenty of contact with nature the farm animals, wildlife, the fresh air and sea. We try to teach inmates that they are part of their environment and that if you harm nature or your fellow man it comes back to you (Prison Governor, Arne Kvernvik Nilsen quoted in Hernu, 2011). Some would say these are words of a man completely deranged. His views and methods of running a prison are the polar opposite to the traditional closed, harsh and costly regimes so commonly seen throughout westernised society. Regardless of opinion, one significant factor remains, this prison is working, in all sense of the meaning. History of self-sufficiency and prisons In 1787 Jeremy Bentham called for prisons to become mills for grinding rogues honest and idle men industrious (Reynolds, 1996). He was not alone in this way of thinking and across the United States incarceration came to be more and more industrious as prisons realised the value of the workforce they had at their disposal. In 1797, Newgate prison opened in New York City and successfully it recouped nearly all of its expenses during the first five years of the operation through prisoner production. The Auburn system named after another New York prison producing superior economic results, dominated U.S. prison culture from 1823. The basis of the Auburn system was to confine prisoners at night but have them come together and work during the day (Reynolds, 1996). For centuries the American prison system sought to function self-sufficiently and according to research conducted by Lyons (2012) the existence of prison farms acted not only as an economically viable way of sufficing prison popu lations, but also functioned as a disciplinary and rehabilitative work program crucial to the 19th century penitentiary. With the successes of working prisons also came criticism, primarily in the form of complaints about unfair competition from prison-made products being created in the public market. Allegations of abuse were also made, accusing prisons of exploiting inmates and concerns were raised over the security of the public. All three criticisms increased political pressure and worked in creating legislative changes. Self-sufficiency as a key element of the penitentiary system was being challenged and continued to be phased out. During the last two decades incarceration in the United States has become increasingly privatised, commercialised and run in favour of corporate profit. Companies such as Aramark and many other suppliers have made substantial profits, through providing prisons with food and other products. Between 1993 and 2000 alone, the US food service industry gen erated 36 billion dollars in profit through contracts with correctional facilities (Lyons, 2012). For over 100 years Canada has had six successfully operating prison farms (Frontenac, Pittsburgh, Westmorland, Riverbend, Rockwood, and Bowden). However, in 2009, the Canadian Corrections Department began taking action towards phasing out the farms, claiming deficits of around four million per annum and suggesting money used to run the farms could be better put into public safety. There has been no proof provided to support such claims of ineffectiveness and those involved with the farms argue this is not the case, with the farms in fact being extremely positive correctional operations. In response to the news of closing the farm community members, correctional officers and ex inmates themselves came together in the national Save Our Prison Farms campaign. The campaign seeks to stall the closure of the prison farms in order to provide non-governmental experts time to collect evidence of the farms viability and benefits (Lyons, 2012). In the United Kingdom prison farm closures began t aking place several years ago. Between 2002 and 2005 the prison service significantly reduced its farming regime from having twenty-three farms, to only the current five. Those currently in operation include; North Sea Camp, Prescoed, Hewell, East Sutton Park and Kirkham but between them only provide a mere 92 inmate work opportunities. They are run on a small scale with no real emphasis of self-sufficiency and have become more about training than anything else (Ministry of Justice, 2010). Although it would appear self-sufficiency in prison is becoming a redundant concept, there are places which are embracing it and achieving successful results. As mentioned above, Bastoy prison in Norway is the quintessential example of an operational self-sufficient prison which is demonstrating the immense value such a prison can have. The origins of Bastoy stem from a Scandinavian ethos of open and active prisons which have throughout time been based on the principle that prisons should be no more arduous than a loss of liberty and be as normal to daily life on the outside as possible. The idea of prison farms began in Finland in the 1930s, with a new type of labour colony being introduced to the Finnish prison system in 1946. Inmates have always been and still are paid according to the normal wage, it would also not be uncommon for prisoners to be paying taxes, buying food, giving money to their family, to their victims and saving for their release. Open prisons hold between 20 % (Sweden) to 40 % (Denmark) of the Scandinavian prison population and in nearly all cases when a prisoner is reaching the end of their sentence they will be moved to an open prison. Communal style living is largely adopted in these facilities, with some prisons being entirely self-catering and for the most part those at an open prison will be working during the day (Pratt, 2008). Most recently, the environmental sustainability of prisons has drawn attention, with concerns being raised about the ecological footprint of corrections and also because of the rehabilitative value green initiatives can have. Just in 2011, the US Department of Justice released the publication The Greening of Corrections: Creating a Sustainable System, a document which outlines sustainable practices, principles and identifies examples of programs and management strategies which can be implemented to create self-sustaining correctional facilities. The focus throughout the document is on the long term goal of limiting the financial and human costs of prisons. Methods outlined to achieve this goal are the reduction of energy and resource use, engaging inmates with beneficial work experiences as well as giving education and training (US Department of Justice, 2011). An organisation going forth and putting these ideals into practice is the Sustainability in Prisons Project. Operating as a partnership between Washington State Corrections and Evergreen College they seek to make prisons more environmentally sustainable and in turn economically efficient. Currently four Washington State correctional centres are operating in unison with the project; Cedar Creek, Stafford Creek, Mission Creek and Washington Corrections Centre for Women. Each are participating in varying programs which include; endangered animal protection, insects and plants, water and energy conservation, motorless lawn mowing, a dog rescue initiative, butterfly rehabilitation program, recycling, composting, organic gardening, a horticulture greenhouse, beekeeping, water catchment basins, low-flush toilets, tree planting and wild land fire fighting. Advantages/Disadvantages When analysing the concept of self-sufficient prisons, there are both advantageous and disadvantageous aspects which need to be acknowledged to gain a complete understanding of the viability of such a prison model. In firstly examining the potential benefits to come from a self-sufficient environment, one of primary significance is the possibility of self-sufficient practices being able to reduce prison expenditure. A change as simple as removing state issued clothing and uniforms could save millions of dollars. Building on this, if prisoners are taking care of themselves, there is consequently less of a need to employ staff to do things such as cooking, cleaning, farming, gardening and maintenance jobs. Having inmates produce and harvest their own food could allow for even greater savings. According to Breslin (2012), if the United States were to enact a policy which required prisons to utilise their own food sources through the operation of self-sufficient farms, prison spending co uld be reduced by $1.7 billion each year. Lyons (2012) similarly supports this notion and she uses the Florida Department of Corrections as a case example. In 2001 they ended a history of prison farming and contracted Aramark to provide all the food needed to Floridas prisons. This was in an attempt to save money, but six years later costs were only increasing by millions of dollars. Costs could only be reduced through a change in prisoners lifestyles, but also through sustainably modifying prison facilities. Buildings can be constructed or altered to be environmentally sustainable. This would include among other things, installing solar panels, composting and recycling plants and farming ecologically. Putnamville medium security facility in Indiana has recently implemented several green initiatives, such as; using a wood chipper that fuels a wood-burning furnace (saving $1.25 million per year), recycling cans, bottles, paper, and other material which in turn saves them around $150, 000 each month (Couch, 2012). An equally valuable advantage of the self-sufficient prison regime is the potential benefit to inmate health, both mentally and physically. Lyons (2012) noted that through being able to exercise, to breath in fresh air, and to simply get outside the confines of cement and barbed wire inmates would be healthier and emotional pressures associated with the harsh prison environment would be abridged. More specifically the mental health of prisoners could be aided through having the intellectual stimulation of actually taking part in meaningful activity, such as harvesting food for their own tables or chopping wood to keep them warm. Successfully completing jobs could also increase the sense of self pride in inmates, seeing they can achieve and successfully live independently. Physical advantages are just as evident, working is obviously a form of exercise and through growing their own organic produce dietary needs would be likely to be met in turn reducing the risk of obesity, high blood pressure and diabetes, all conditions stemming from unhealthy eating patterns. Additionally, with an increase in the overall health of inmates, money would be saved on prison medical services (Breslin, 2012). Correlations have been drawn between a better quality of living and the improved behaviour and conduct of inmates. When interviewed about life inside Bastoy, an inmate tractor driver said in closed prison I was locked up for 23 hours a day, so Im really happy with this job. I am treated very well here and in return I will treat them very well also (Hernu, 2011).   A US post-release employment project study found prison conduct among inmates who had taken part in work, vocational or apprenticeship programs was better than that of otherwise similar prisoners (Reynolds, 1996). Related to having the opportunity to work and live self-sufficiently in prison is the education and vocational skills prisoners could learn. As suggested by Lyons(2012), the job and life skills that inmates learn through farming, teamwork, time management and having responsibility can be applicable to any type of future work. In now turning to the potential downfalls of the self-sufficient model, the most notable disadvantage is the safety risk an open style of prison poses. Internally there is an increased risk of danger to both inmates and officers safety and externally there is a greater risk of endangerment of the public due to more opportunities for escape. Firstly, if inmates are openly living and working with each other there are going to be vast opportunities for violence and abuse to take place, especially when tools which could be used as weapons are involved. Constant movement would make it harder for guards to keep track of inmates, whereas when in a cell all day constant monitoring can occur. Secondly, guards would be more susceptible to harm in an environment where there is frequent close interaction between themselves and inmates. Trust is so heavily relied upon in a community based self-sufficient model that if this was abused there could be dire consequences. The possibility of threats to public safety could also be said to increase, as with more freedom come more chances to escape and be at large in general society. A risk associated directly with working in prison is the exploitation of inmates. Frequently outlined in prison research as a significant disadvantage of prison farms; this concern lies in the possibility of production becoming more important than any other factor, including the welfare of the prisoners who can become subject to hard labour and little else. There have been numerous situations where agricultural work in prison has been the catalyst of degrading and unhealthy working conditions exposing inmates to disease, physical violence and abusive practices (Lucko, 2007). For some, the idea of prisoners living in a community like environment, which includes recreational time and the opportunity to live a life based on normality, would fall short in serving the retributive role prisons are traditionally expected to provide. Victims and their families may feel this alternative model of prison does not adequately punish perpetrators for the crimes they have committed against them. Monetary exploitation can also occur through inmates being extremely under paid for their labour when working on farms, building furniture or assembling products for giant multi-national corporations who can make additional profits at the expense of prisoners. Resulting from this is the possibility of large corporations like Microsoft or McDonalds engaging in the practice of utilising prison labour and gaining an unfair advantage over their competitors (Smith and Hattery, 2006). Rehabilitation and self-sufficient prisons If we have created a holiday camp for criminals here, so what? We should reduce the risk of reoffending, because if we dont, whats the point of punishment, except for leaning toward the primitive side of humanity? (Arne Kvernvik Nilsen, quoted in Sutter, 2012). This quote demonstrates the strong rehabilitative views of Bastoys prison director, who currently heads the prison with lowest reoffending rate in Europe. He strongly believes in the theory that if inmates are eventually going to end up being somebodys neighbour, everything possible should be done to enhance rehabilitation and ultimately prevent future crime. The proof of his beliefs becoming a reality are evident in the correlations which can be drawn between the self-sufficient and open environment at Bastoy and the mere 16% reoffending rate. In attempting to ascertain whether any particular element of the self-sufficient regime is more effective than another in reducing reoffending, each of the main facets of the concept will be examined below. A vast amount of support has been given for the effectiveness of farming and/or working in prisons. Lyons (2012) suggests that there are two main steps which need to be taken for the cycle of criminality to be broken. The first, individual empowerment and the second, being able to find work upon release. Farming she believes is a proven success in helping prisoners to achieve both. To get a real perspective on farming as a rehabilitative tool Lyons (2012) interviewed a former correctional officer from a Canadian prison farm. In their opinion prison farming is the single-most successful rehabilitation program they have seen to exist, and that in their thirty years working with the program they did not see one case of violent reoffending amongst prisoners who had been involved. Another aspect of the self-sufficient philosophy being explored here is the openness this type of prison has. In contrast to the more traditional closed ideal where prisoners spend a vast majority of their time behind bars, in an open style prison inmates are faced with everyday decisions on constant basis. Bastoy governor Nilsen suggests that at Bastoy the openness of the prison allows for inmates to learn and be taught how to make the right decisions and essentially become better people. He compares this to in a closed prison where prisoners are mostly removed from interactive encounters and situations requiring cognitive thinking. This he refers to as treating prisoners like animals or robots (Sutter, 2012). In a conventional prison in which inmates have no freedom and are not involved with work or farming, it is too often the case that the system literally closes the door in the face of the inmate. It is surely absurd to really believe that this will be beneficial, especially in terms of rehabilitation. Being given the personal responsibility of a job in prison and becoming a part of a working environment has the potential for prisoners to increase self-respect, as well as respect for others such as the system which would be supporting instead of disregarding them. When describing the effect Bastoys open prison has had on inmates, Nilsen refers to opportunities inmates have here to do more than just sit in a cell all day. They look at themselves in the mirror, and they think, I am s***. I dont care. I am nothing,' he said. This prison, he says, gives them a chance to see they have worth, to discover, Im not such a bad guy (Nilsen quoted in Sutton, 2012). The ecological focus of a self-sufficient prison model not only contributes to a sustainable environment, but has also been linked having to rehabilitative qualities. When daily life is spent in a safe, healthy and humane environment, on release the positive and green initiatives experienced inside can surely only be of benefit to the community on release . Research has been carried out to support such assumptions and uncover any relationships existent between living sustainably, having exposure to nature and consequential prisoner rehabilitation. Wener et al (cited in US Department of Justice, 2011) found that the effect of interaction with nature on human behaviour is improved emotional wellbeing. Similarly in a separate study conducted by Ulrich (cited in US Department of Justice, 2011) it was established that through being involved with nature aggressive tendencies and stress can both be reduced. In evaluating the value of the Sustainable Prison Project currently already action i n Washington, the Department of Justice (2011) believes that benefits of these projects are wide-ranging and encompass far more than just learning new skills. Their review of the project found improvements in; inmate self-esteem, interactions with others and the sense of purpose they had. All of which are congruent with the goal rehabilitation. With a vast amount of studies and research highlighting increases in recidivism and re-offending figures, we are faced with a significant correctional challenge. It is no longer plausible to simply argue that prison acts as a place of deterrence to those released, the statistics alone have continuously portrayed the reality that this is not working. Self-sufficient prisons in a New Zealand environment After considering the concept of self-sufficient prisons in their entirety , the viability of this alternative prison model successfully working in a New Zealand context will now be addressed. In comparing New Zealand to Norway, where a self-sufficient prison is already proving achievable, there are numerous similarities between the countries which could arguably suggest a New Zealand environment could too be compatible with this correctional method. Both countries are sparsely inhabited with populations of around four million, many of whom in both countries live as part of small rural communities of towns, rather than large sprawling cities. Norway in terms of a social and human development index is the number one ranked country, but then New Zealand is also within the top five out of 187 countries (Human Development Report, 2011). Other factors relative to this assessment include New Zealands small number of maximum security inmates, just 2.5%. The majority, or 53.8 % are in fact minimum security (Newbold, 2005). It would seem with such a large number of prisoners being of low security, the risks associated with adopting a more open and interactive model of prison to house this category of prisoners would be relatively low. We also already have the beginnings of a self-sufficient prison mentality in place. Currently in operation are various income generating ventures providing employment opportunities for prisoners, this includes; two dairy farms, three dry stock farms, one piggery, two sheep farms, three organic gardens, six nurseries, five joinery workshops, three furniture assembly workshops, a forest, three timber processing workshops, six textile workshops, three light engineering workshops, three vehicle repair garages, one compost bagging operation and central kitchens in each of New Zealands   prison s (Department of Corrections, 2012). The progression towards a model similar to Bastoy is not completely unthinkable. As outlined, New Zealand has the potential to follow the same path as Norway in adopting more sustainable practices. However, the possible limitations of New Zealands capability to introduce self-sufficient prisons cannot be ignored. One major aspect which not only differentiates New Zealand from Norway, but could also limit the success of self-sufficient prisons in this context, is culture. Negative historical relations between Maori and the State are still today at the centre of much racism, mistrust and social division and this plays a role in crime and prison culture, especially when Maori are so significantly overrepresented in our prisons. Due to the nature of the traditional system, which places blatant divides between prisoners and correctional staff, both parties can fall into viewing each other as the enemy. These attitudes would have to change and mutual trust and respect increased before any community style prison could work. The Gang culture in New Zealand and incidentally in prison creates even more division and an open style of prison may only serve to instigate fighting, allow for gang conflicts and gang domination of inmates. In Norway these types of divisions are relatively absent, primarily due to the fact Norwegians are extremely socially responsible, uniting members of society together as equals. This can especially be seen in the understanding the state, public and even the media display to those in prison, those being released and the rehabilitative purpose prison serves. Associated with this social care mentality is the time and effort that the state puts into training prison officers. In Norway they receive two years training while on full salary and once qualified their role is seen as professional (Pratt, 2007). Contrastingly, in New Zealand, officers are given a mere six weeks training and are often publically disregarded being labelled thugs or key turners far from the professionalism of Norway. Scandinavian prisons are completely run by the state, where as in New Zealand the Government has begun to contract prisons to private companies. Paying for another party to run the prison would defeat the principles behind the self-sufficient ideal. Mass unawareness can be the burden of initiative, even of something which to those informed is so obviously for the common good of society. This is arguably the case in New Zealand, where people simply havent been informed or are only given negative one-eyed images of crime as portrayed through the media. This consequently making the public as a whole more likely to be opposed to an action as liberal and forward thinking as the self-sufficient prison ideal. Another more physical consideration which could pose problems is the pure and simple fact that more crime is committed in New Zealand and the prison population is therefore larger. In New Zealand there are around 8000 inmates whilst in Norway there are only 3000. Geographically there could also be obstacles to overcome. Bastoy is uniquely located on its own island, which restricts escapes and allows for the open environment which inmates experience. Suggesting to the New Zealand public that Rangitoto for example was to be used

Mobile Ad Hoc Networks (MANETs)

Mobile Ad Hoc Networks (MANETs) Introduction What is Mobile Ad Hoc Network? With rapid development of wireless technology, the Mobile Ad Hoc Network (MANET) has emerged as a new type of wireless network. MANET is a collection of wireless mobile nodes (e.g. laptops) that dynamically function as a network without the use of any existing infrastructure and centralized administration. It is an autonomous system where each node operates not only as an end system but also as a router to forward packets for other nodes. Since the nodes in MANET move around, the wireless links break and re-establish frequently. Furthermore, most of mobile nodes are resource limited in computing capability and battery power and therefore traditional computing content routing protocols are not suitable for MANET. Several ad hoc routing protocols have been proposed for each node acting as router and maintaining routing information. There are many other applications of MANET. For examples, MANET can be used to provide emergency Services when the network is impaired due to the damaging of existing infrastructure [8]. Computer scientists have predicted a world of ubiquitous computing in which computers will be all around us, constantly performing mundane tasks to make our lives a little easier. These ubiquitous computers connect in mobile ad hoc mode and change the environment or react to the change of the environment where they are suited. MANET is also found useful in the so-called sensor dust network to coordinate the activities and reports of a large collection of tiny sensor devices which could offer detailed information about terrain or environmental dangerous conditions. Problem Statement and Motivation Most current ad hoc routing protocols assume that the wireless network is benign and every node in the network strictly follows the routing behavior and is willing to forward packets for other nodes. Most of these protocols cope well with the dynamically changing topology. However, they do not address the problems when misbehavior nodes present in the network.A commonly observed misbehavior is packet dropping. In a practical MANET, most devices have very limited computing and battery power while packet forwarding consumes a lot of such resources. Thus some of the mobile devices would not like to forward the packets for the benefit of others and they drop packets not destined to them. On the other hand, they still make use of other nodes to forward packets that they originate. These misbehaved nodes are very difficult to identify because we cannot tell that whether the packets are dropped intentionally by the misbehaved nodes or dropped due to the node having moved out of transmission range or other link error. Packet drop significantly decreases the network performance.Traditional security mechanisms are generally not suitable for MANET because: The network lacks central infrastructure to apply traditional security mechanism such as access control, authentication and trusted third party. Limited bandwidth, battery lifetime, and computation power prohibits the deployment of complex routing protocols or encryption algorithms. New security models or mechanisms suitable for MANET must be found. Network topologies and memberships are constantly changing. Thus new intrusion detection system and entity recognition mechanisms that are suitable for mobile ad hoc networks must be designed to avoid or mitigate the behavior to the networks. Trust management systems have been recently introduced as a security mechanism in MANET. In a trust management system, a communicating entity collects evidence regarding competence, honesty or security of other network participants with the purpose of making assessment or decisions regarding their trust relationships. Here trust Objective and Sub-tasks means the confidence of an entity on another entity based on the expectation that the other entity will perform a particular action important to the trustor, irrespective of the ability to monitor or control that other entity . For example, a trust-based routing protocol can collect the evidence of nodes misbehaving, form trust values of the nodes and select safest routes based on the trust metrics.Reputations systems are often seen as a derivation of trust management system. In the reputation system, an entity forms its trust on another entity based not only on the selfobserved evidence but also on the second hand information from third parties. One of the influential reputation systems is the DSR protocol. In the trust management system, reputation system and other trust-based systems, route selection is based on the sending nodes prior experience with other nodes in the network. Its opinions about how other entities are honest are constantly changing. Thus, we call the trust manag ement systems and their derivations as dynamic feedback mechanisms. The dynamic feedback mechanisms are usually applied on the current ad hoc routing protocols to rate the trust about other nodes in the network and make routing decisions based on the trust matrix, which is formed according to the evidence collected from previous interactions. By incorporating the dynamic feedback mechanism in the routing protocol, misbehaved nodes are identified and avoided to forward packets. In this way,misbehavior can be mitigated. Objective and Sub-tasks The primary objective of this thesis is to Investigate the state of the art of dynamic feedback mechanisms and protocols analyze, implement and evaluate DSR protocols to see how it improves the network performance and what are the side effects of introducing the mechanism to the mobile ad hoc network. Following tasks must be done to achieve the primary objective. Study the preliminary knowledge that is required to carry out the main tasks. For example, to understand DSR protocol one must have some knowledge of Bayesian analysis; to do performance analysis one must learn the methodologies of conducting performance analysis and processing simulation data. Investigate security issues of mobile ad hoc network and current dynamic feedback mechanisms or protocols that are used to solve or mitigate the issues. Investigate and learn how to use the network simulation tool. There are several popular network simulation tools available and we need to choose the one that best suits our needs. The selected network simulator should be studied so that we can use it as platform to implement protocol and conduct simulations. Analyze and implement the DSR protocol based on Dynamic Source Routing protocol (DSR); evaluate the network performance. Structure of the Report Since we have almost gone through the chapter one, we only briefly present the content of the subsequent chapters in this section. Preliminary Information State of the Art Analysis Design Implementation and Tests Performance Analysis Conclusion and Future Work Preliminary information we have introduced the MANET. This chapter presents other preliminary information and concepts that will be used in other parts of the thesis. Firstly four general modes of routing operations are introduced and compared. The DSR protocol, which is used as underlying routing protocol in the thesis, is explained in detail. Secondly Bayesian estimation and Beta function are explained to pave the way for the analysis of the reputation model of DSR in the chapter 4. Thirdly some techniques regarding simulation and performance analysis are presented. Finally, several popular network simulation tools are discussed and compared. Mobile Ad Hoc Network Routing Protocols Nowadays there are various routing protocols proposed for the MANET. The most popular ones are DSDV (Destination-Sequenced Distance Vector), TORA (Temporally- Ordered Routing Algorithm), DSR (Dynamic Source Routing) and AODV (Ad-hoc On Demand Distance Vector). These routing protocols can be categorized in different routing operation modes. Mode of Routing Operations These two modes concern whether or not nodes in an ad hoc network should keep track of routes to all possible destinations, or instead keep track of only those destinations of immediate interest Proactive protocols store route information even before it is needed. This kind of protocols has advantage that communications with arbitrary destination experience minimal delay. However it also suffers from the disadvantage that additional control traffic is needed to continually update stale route information. This could significantly increase routing overhead especially for the MANET where the links are often broken. Reactive protocols, on the contrary, acquire routing information only when it is actually needed. However, the latency of the communication increases tremendously especially when a node communicates to another at the first time. Source routing vs. Hop-by-hop routing These two modes concern whether the source node decides the route for a packet to be forwarded to the destination or the intermediate nodes are allowed to decide the next hop until the packet arrives at the destination. In the source routing protocols, the source node decides the route and puts the route information in the packet header. All the intermediate nodes forward the packet along the route faithfully. This kind of protocols has advantage that the intermediate nodes are not required to maintain the routing information. But it suffers from the disadvantage that the packet size grows because of source routing information carried in each packet. In the hop-by-hop routing protocols, it is sufficient for the source to know only how to get to the next hop and intermediate nodes find their own next-hops until the destination. In contrast to source routing protocols, hop-by-hop routing protocols do not increase packet size but they requires all the intermediate nodes to maintain rout ing information. Table 2-1 Categories of routing protocols has compared the performance of these four routing protocols . The results show that DSR has best throughput performance (above 95%) at all mobility rates and movement speeds. Thus we will use DSR as basic routing protocol in this thesis. The Dynamic Source Routing Protocol (DSR) John et al. proposed the dynamic source routing protocol (DSR) [1] which is a routing protocol for use in multi-hop wireless ad hoc networks of mobile nodes. DSR is an ondemand protocol, in which route are only discovered when data need to be transmitted to a node where no route has yet been discovered. The advantage of this on-demand routing protocol is that there are not any periodic routing advertisement and reducing the routing overhead. DSR is also a source routing protocol, allowing multiple routes to any destination and allows each sender to select and control the routes used in routing the packets. DSR is composed of the two main mechanisms: Route Discovery and Route Maintenance which are explained below. Route Discovery Route Discovery aims at finding routes from a source node to destination. Figure 2-1 illustrates the procedure of Route Discovery. When a source node S wants to send a data packet to some destination node D, it first searches its route cache to find whether there is a route to D. If there is no route to D, then S will initiate a Route Discovery and send out Route Request message which is propagated to all the nodes within its transmission range. At the mean time, it saves the data packet in its send buffer. The Route Request message contains the addresses of source node and destination node, a unique route request identifier and a route record which records all the intermediate nodes that this route request packet has traveled through. S appends itself to the beginning of the route record when it initiates the message. When a node receives the Route Request message, it compares the destination address in the message with its own address to judge whether itself is the destination node. If it is not, it will append its own address in the route record and propagate the message to other nodes. If the node is the destination node, it will send a Route Reply message to the source node and the message contains the source route record which is accumulated when the Route Request message is forwarded along its way to the destination. When the destination sends the Route Reply, if it uses MAC protocols such as IEEE 802.11 that require a bidirectional link, it just reverse the source route record and use it as route to send Route Reply to the source node. Otherwise it should find the route by searching its route cache or sending out a Route Request which piggybacks the Route Reply for the source node. When the source node receives the Route Reply message, it puts the returned route into its route cache. From t hen on all the packets destined to the same destination will use this route until it is broken. Route Maintenance Since the ad hoc network is dynamic and the topology of the network changes frequently, the existing routes maintained by nodes in their route cache are often broken. After forwarding a packet, a node must attempt to confirm the reachability of the next-hop node. If the node does not receive any confirmation from the next hop during a certain period of time, it will retransmit the packet. If after a maximum number of retransmission it still does not receive any confirmation, it will think the link to the next hop is broken and will send a Route Error message to the source node. DSR proposes three acknowledge mechanisms to confirm that data can flow over the link from that node to the next hop: Link-layer acknowledgement which is provided by MAC layer protocol such as IEEE 802.11. Passive acknowledgement in which a node hears the next-hop node forwarding the packet and thus confirms the reachability of the link. Network-layer acknowledgement in which a node sends an explicit acknowledgement request to its next-hop node. Passive Acknowledgement Passive Acknowledgement (PACK) is important in DSR protocol because it is used to detect whether the next hop forwards the packet or drops it. We explain it in detail in this section. Passive acknowledgement is used with the assumption that: Network links operates bi- directionally. The network interface is in the promiscuous mode. When a node taps a new packet in promiscuous mode after it originates or forwards a packet, it consider it as an acknowledgement of the first packet if both of following check success. The Source Address, Destination Address, Protocol, Identification, and Fragment Offset fields in the IP header of the two packets MUST match. If either packet contains a DSR Source Route header, both packets MUST contain one, and the value in the Segments Left field in the DSR Source Route header of the new packet MUST be less than that in the first packet. If no matched packet is found during PACK timeout, the node will consider the link between the next hop and itself is broken and will send Route Error message to the source node. Additional features DSR has additional features such as replying to route requests using cached routes, caching overheard routing information, packet salvaging and flow state extension and etc. We will introduce them in section 4.1 and discuss how they will impact the performance of network, how they will interact with DSR and whether they will be enabled in our simulation. Performance Analysis Techniques This section introduces the performance analysis techniques and methodologies that will be used in the performance evaluation. Factors and Primary Factors There are many parameters that will influence the simulation results and need to be carefully chosen in the simulations. Some parameters are chosen based on experience values or the conditions of the network we want to simulate. Others need to be tuned to optimize the network performance. We distinguish the two kinds of parameters as follows: Factors are the variables that affect the simulation result and have several alternatives. Normally they are decided based on experience. Primary factors are the factors whose effects need to be quantified. This kind of factors usually needs to be adjusted through simulation. Data Measurement The key step of the network performance analysis is to interpret the simulation result and summarize the characteristic of the network. To avoid the inaccurate simulation results due to an extreme scenario, we usually run simulations on several different scenarios. The data set of these simulations are called sample. A single number must be presented to give the key characteristic of the sample and this single number is called an average of the data. There are three alternatives to summarize a sample Mean is obtained by taking the sum of all observations and dividing this sum by the number of observations in the sample. Median is obtained by sorting the observations in an increasing order and taking the observation that is in the middle of series. If the number of the observations is even, the mean of the middle two values is used as a median. Mode is obtained by plotting a histogram and specifying the midpoint of the bucket where the histogram peaks. Confidence Interval for the Mean In our performance evaluation, the main objective is to compare the simulation results of DSR and Standard DSR to see whether there is any performance improvement. However, most simulation results are random in some degree due to the particularity of the node movement scenarios and we cannot tell whether the two systems are different. One way to minimize the random effect is to repeat the simulations with different scenarios as many times as possible and get a large sample space. Unfortunately, due to the time limitation we cannot conduct many simulations. points out that using confidence interval we can tell whether the two systems are different with smaller sample space. The confidence interval for the mean can be calculated using If the confidence intervals of the simulation results of the two systems have no overlap, then we can claim the two systems are different and one system is superior or inferior to the other. GloMoSims source and binary code can be downloaded only by academic institutions for research purposes. Commercial users must use QualNet, the commercial version of GloMoSim. OPNET Modeler OPNET Modeler is commercial network simulation environment for network modeling and simulation. It allows the users to design and study communication networks, devices, protocols, and applications with flexibility and scalability [30]. It simulates the network graphically and its graphical editors mirror the structure of actual networks and network components. The users can design the network model visually.The modeler uses object-oriented modeling approach. The nodes and protocols are modeled as classes with inheritance and specialization. The development language is C. Comparison When choosing a network simulator, we normally consider the accuracy of the simulator. Unfortunately there is no conclusion on which of the above three simulator is the most accurate one. David Cavin et al. has conducted experiments to compare the accuracy of the simulators and it finds out that the results are barely comparable [31]. Furthermore, it warns that no standalone simulations can fit all the needs of the wireless developers. It is more realistic to consider a hybrid approach in which only the lowest layers (MAC and physical layers) and the mobility model are simulated and all the upper layers (from transport to application layers) are executed on a dedicated hosts (e.g. cluster of machines). Although there is no definite conclusion about the accuracy of the three network simulators, we have to choose one of them as our simulation environment. We compare the simulators using some metrics and the results are summarized After comparing the three simulators, we decide to choose ns2 as network simulator in our thesis because Ns2 is open source free software. It can be easily downloaded and installed. The author of the thesis has used ns2 in another network related course and gotten familiar with the simulation. Ns2 uses TCL and C++ as development languages for which the author has some programming experience. The author of the DSR protocol has conducted simulation on GloMoSim and gotten performance results. We want to do the simulation on a different simulation to form comparison. State of the Art In this chapter we will introduce the start of the art security solutions in MANET with emphasis on dynamic feedback mechanisms. Firstly, we will present the general security issues/requirements of MANET to pave the way for the future investigation. Then we will discuss the state of the art security mechanisms for MANET such as payment system,trust management system, reputation system, etc. Finally, we will summarize all the security solutions we discussed in this chapter. Security Issues in Mobile Ad Hoc Network Due to lack of central infrastructural and wireless links susceptible to attacks, security in ad hoc network has inherent weakness. In section 1.2 we have discussed the reasons why mobile ad hoc network imposes security challenges that cannot be solved by traditional security mechanisms. In this section, we present the general security properties required by ad hoc network. Following are general security properties regarding ad hoc network Confidentiality: The confdiantiality property is to protect certain information from unauthorized disclosure. The information includes not only the application data that send over the routing protocol, but also the routing information itself as well as network topology and geographical location. Integrity: The integrity ensures that the transmitted message and other system asset are modified only by authorized parties. In the routing level, it requires all nodes in the network following correct routing procedure. The main challenge of ensuring integrity is that without central infrastructure and powerful computing capabilities, it is difficult to apply existing cryptography and key management systems. Availability: The availability property requires that the services or devices are exempt from denial of service, which is normally done by interruption, network or server overload. Typical examples or denial of service attack are radio jamming, in which a misbehaved node transmit radio to interference other nodes communications, and battery exhaustion, in which a misbehaved node interact with a node for no other purpose than to consume its battery energy. Authentication: The authentication property requires that the communication entitys identification is recognized and proved before communication starts. Access control: This property requires restricting resources, services or data to special identities according to their access rights or group membership. Non-repudiation: This property ensures that when data are sent from sender to receiver, the sender cannot deny that he has sent the data and the receiver cannot deny that he has received the data. Mobile nodes may conduct different misbehavior for different purposes. Po-Wah Yau classifies the misbehaved nodes into following categories. Failed nodes are simply those unable to perform an operation; this could be because power failure and environmental events. Badly failed nodes exhibit features of failed nodes but they can also send false routing messages which are a threat to the integrity of the network. Selfish nodes are typified by their unwillingness to cooperate as the protocol requires whenever there is a personal cost involved. Packet dropping is the main attack by selfish nodes. Malicious nodes aim to deliberately disrupt the correct operation of the routing protocol, denying network service if possible. These four types of misbehaved nodes actually can be categorized in two aspects: whether their misbehaviors are intentional or unintentional, and the severity of the results. Payment Systems Payment systems provide economic incentives for the cooperation in MANET. They consider that each node in MANET is its own authority and tries to maximize the benefits it gets from the network. Thus each node tends to be selfish, dropping packets not destined to them but make use of other nodes to forward their own packets. The purpose of payment systems is to encourage the cooperation within the MANET by economic incentives. There are several variations of payment systems proposed. Nuglets Nuglets is a virtual currency mechanism for charging (rewarding) server usage (provision). Nodes that use a service must pay for it (in nuglets) to nodes that provide the service. A typical service is packet forwarding which is provided by intermediate nodes to the source and the destination of the packet. Therefore either the source or the destination should pay for it. There are two models for charging for the packet forwarding service: the Packet Purse Model (PPM) and the Packet Trade Model (PTM). In the Packet Purse Model, the sender pays for the packet. It loads the packet with a number of nuglets when sending the packet. Each intermediate forwarding node acquires some nuglets from the packet that covers its forwarding costs. If a packet does not have enough nuglets to be forwarded, then it is discarded. If there are nuglets left in the packet once it reaches destination, the nuglets are lost. In the Packet Trade Model, the destination pays for the packet. Each intermediate node buys the packet from previous one for some nuglets and sells it to the next one for more nuglets until the destination buys it. Either of the two models has advantages and disadvantages. While the Packet Purse Model deters nodes from sending useless data and avoids the network overloading, the Packet Trade Model can lead to an overload of the network and the destination receives packets it does not want. On the other hand, in the Packet Purse Model it is difficult to estimate the number of nuglets th at are required to reach a given destination. But thePacket Purse Model does not need to consider this problem. To take advantages of the two models and avoid the disadvantages, a hybrid model is suggested. In this model, the sender loads the packet with some nuglets before sending it.The packet is handled according to the Packet Purse Model until it runs out of nuglets. Then it is handled according to the Packet Trade Model until the destination buys it. Counter To address the problems encountered by the nuglets approach such as difficulty in estimating pre-load nuglets and possible network overload, another payment approach based on credit counter is suggested. In this approach, the current state of each node is described by two variables b and c, where b is the remaining battery power and cstands for the value of its nuglet counter. More precisely, b is the number of packets that the node can send using its remaining energy and c is the number of packets a node canoriginate. A node can originate a number of packets N only when the condition c=N holds. When a node forwards a packet, nuglet counter c is increased by one and b is reduced by one. Thus in order to originate packets, each node must earn credits by forwarding packets. The counter solution requires tamper resistant hardware security module. Spirit S. Zhong et al. proposed Sprite [19], a credit-based system for MANET. As opposed to Nuglets or Counter they do not require tamper-proof hardware to prevent the fabrication of payment units. Instead, they introduce a central Credit Clearance Service (CCS). The basic scheme of the system is as follows. When a node receives a message the node keeps a receipt of the message and reports to the CCS when the node has a fast connection to Credit Clearance Service (CCS). The CCS then determines the charge and credits to each node involved in the transmission of a message, depending on the reported receipts of a message. In this scheme, the sender charges money. A node that has forwarded a message is compensated, but the credit that a node receives depends on whether or not its forwarding action is successful. Forwarding is considered successful if and only if the next node on the path reports a valid receipt to the CCS. Discussion on the Payment Systems The payment systems we describe in above sections either assumes a tamper resistant hardware module is available to ensure that the behavior of the node is not modified or requires a central authority server to determine the charge and credit to each node involved in the transmission of a message. Tamper resistant hardware may not be appropriate for most mobile devices because it demands advanced hardware solution and increases the cost of the devices. Lacking of central authority server is right the inherent property of MANET that causes security challenges so it is also not appropriate. Furthermore, all the approaches described above suffer from locality problems [20] that nodes in different locations of the network will have different chances for earning virtualcurrency, which may not be fair for all nodes. Usually nodes at the periphery of the network will have less chance to be rewarded. Reputation System Reputation systems have emerged as a way to reduce the risk entailed in interactions among total strangers in electronic marketplace. Centralized reputation systems have been adopted by many on-line electronic auctions such as eBay to collect and store reputation ratings from feedback providers in a centralized reputation database. Decentralized reputation systems used by MANET, on the other hand, do not use centralized reputation database. Instead, in these reputation systems, each node keeps the ratings about other node and updating the ratings by direct observation of the behaviorsof neighboring nodes or second hand information from other trusted nodes. Identifies three goals for reputation systems: To provide information to distinguish between a trust-worthy principal and an untrustworthy principals. To encourage principals to act in a trustworthy manner To discourage untrustworthy principals from participating in the service the reputation mechanism is present to protect. Most of the reputation systems in MANET are based on trust management system. Trust is such a subjective and dynamic concept that different entities can hold different opinions on it even while facing the same situation. Trust management system can work without reputation system. For example, a mobile node can form opinion about other nodes by direct experience with the nodes.We can unify reputation system and trust management system to dynamic feedback mechanisms. Former one is a global reputation system and mobile nodes share their own experiences of interaction with other nodes. The later one is a local reputation system in which mobile nodes rating the trustability of other nodes based on its own observation. DSR DSR is a reputation system aiming at coping with misbehavior in MANET. The idea is to detect the misbehaved nodes and isolate them fromcommunication by not using them for routing and forwarding and by not allowing the misbehaved nodes to use itself to forward packets. DSR stands for Cooperation Of Nodes: Fairness In Dynamic Ad-hoc Network. It usually works as an extension to on demand routing Mobile Ad Hoc Networks (MANETs) Mobile Ad Hoc Networks (MANETs) Introduction What is Mobile Ad Hoc Network? With rapid development of wireless technology, the Mobile Ad Hoc Network (MANET) has emerged as a new type of wireless network. MANET is a collection of wireless mobile nodes (e.g. laptops) that dynamically function as a network without the use of any existing infrastructure and centralized administration. It is an autonomous system where each node operates not only as an end system but also as a router to forward packets for other nodes. Since the nodes in MANET move around, the wireless links break and re-establish frequently. Furthermore, most of mobile nodes are resource limited in computing capability and battery power and therefore traditional computing content routing protocols are not suitable for MANET. Several ad hoc routing protocols have been proposed for each node acting as router and maintaining routing information. There are many other applications of MANET. For examples, MANET can be used to provide emergency Services when the network is impaired due to the damaging of existing infrastructure [8]. Computer scientists have predicted a world of ubiquitous computing in which computers will be all around us, constantly performing mundane tasks to make our lives a little easier. These ubiquitous computers connect in mobile ad hoc mode and change the environment or react to the change of the environment where they are suited. MANET is also found useful in the so-called sensor dust network to coordinate the activities and reports of a large collection of tiny sensor devices which could offer detailed information about terrain or environmental dangerous conditions. Problem Statement and Motivation Most current ad hoc routing protocols assume that the wireless network is benign and every node in the network strictly follows the routing behavior and is willing to forward packets for other nodes. Most of these protocols cope well with the dynamically changing topology. However, they do not address the problems when misbehavior nodes present in the network.A commonly observed misbehavior is packet dropping. In a practical MANET, most devices have very limited computing and battery power while packet forwarding consumes a lot of such resources. Thus some of the mobile devices would not like to forward the packets for the benefit of others and they drop packets not destined to them. On the other hand, they still make use of other nodes to forward packets that they originate. These misbehaved nodes are very difficult to identify because we cannot tell that whether the packets are dropped intentionally by the misbehaved nodes or dropped due to the node having moved out of transmission range or other link error. Packet drop significantly decreases the network performance.Traditional security mechanisms are generally not suitable for MANET because: The network lacks central infrastructure to apply traditional security mechanism such as access control, authentication and trusted third party. Limited bandwidth, battery lifetime, and computation power prohibits the deployment of complex routing protocols or encryption algorithms. New security models or mechanisms suitable for MANET must be found. Network topologies and memberships are constantly changing. Thus new intrusion detection system and entity recognition mechanisms that are suitable for mobile ad hoc networks must be designed to avoid or mitigate the behavior to the networks. Trust management systems have been recently introduced as a security mechanism in MANET. In a trust management system, a communicating entity collects evidence regarding competence, honesty or security of other network participants with the purpose of making assessment or decisions regarding their trust relationships. Here trust Objective and Sub-tasks means the confidence of an entity on another entity based on the expectation that the other entity will perform a particular action important to the trustor, irrespective of the ability to monitor or control that other entity . For example, a trust-based routing protocol can collect the evidence of nodes misbehaving, form trust values of the nodes and select safest routes based on the trust metrics.Reputations systems are often seen as a derivation of trust management system. In the reputation system, an entity forms its trust on another entity based not only on the selfobserved evidence but also on the second hand information from third parties. One of the influential reputation systems is the DSR protocol. In the trust management system, reputation system and other trust-based systems, route selection is based on the sending nodes prior experience with other nodes in the network. Its opinions about how other entities are honest are constantly changing. Thus, we call the trust manag ement systems and their derivations as dynamic feedback mechanisms. The dynamic feedback mechanisms are usually applied on the current ad hoc routing protocols to rate the trust about other nodes in the network and make routing decisions based on the trust matrix, which is formed according to the evidence collected from previous interactions. By incorporating the dynamic feedback mechanism in the routing protocol, misbehaved nodes are identified and avoided to forward packets. In this way,misbehavior can be mitigated. Objective and Sub-tasks The primary objective of this thesis is to Investigate the state of the art of dynamic feedback mechanisms and protocols analyze, implement and evaluate DSR protocols to see how it improves the network performance and what are the side effects of introducing the mechanism to the mobile ad hoc network. Following tasks must be done to achieve the primary objective. Study the preliminary knowledge that is required to carry out the main tasks. For example, to understand DSR protocol one must have some knowledge of Bayesian analysis; to do performance analysis one must learn the methodologies of conducting performance analysis and processing simulation data. Investigate security issues of mobile ad hoc network and current dynamic feedback mechanisms or protocols that are used to solve or mitigate the issues. Investigate and learn how to use the network simulation tool. There are several popular network simulation tools available and we need to choose the one that best suits our needs. The selected network simulator should be studied so that we can use it as platform to implement protocol and conduct simulations. Analyze and implement the DSR protocol based on Dynamic Source Routing protocol (DSR); evaluate the network performance. Structure of the Report Since we have almost gone through the chapter one, we only briefly present the content of the subsequent chapters in this section. Preliminary Information State of the Art Analysis Design Implementation and Tests Performance Analysis Conclusion and Future Work Preliminary information we have introduced the MANET. This chapter presents other preliminary information and concepts that will be used in other parts of the thesis. Firstly four general modes of routing operations are introduced and compared. The DSR protocol, which is used as underlying routing protocol in the thesis, is explained in detail. Secondly Bayesian estimation and Beta function are explained to pave the way for the analysis of the reputation model of DSR in the chapter 4. Thirdly some techniques regarding simulation and performance analysis are presented. Finally, several popular network simulation tools are discussed and compared. Mobile Ad Hoc Network Routing Protocols Nowadays there are various routing protocols proposed for the MANET. The most popular ones are DSDV (Destination-Sequenced Distance Vector), TORA (Temporally- Ordered Routing Algorithm), DSR (Dynamic Source Routing) and AODV (Ad-hoc On Demand Distance Vector). These routing protocols can be categorized in different routing operation modes. Mode of Routing Operations These two modes concern whether or not nodes in an ad hoc network should keep track of routes to all possible destinations, or instead keep track of only those destinations of immediate interest Proactive protocols store route information even before it is needed. This kind of protocols has advantage that communications with arbitrary destination experience minimal delay. However it also suffers from the disadvantage that additional control traffic is needed to continually update stale route information. This could significantly increase routing overhead especially for the MANET where the links are often broken. Reactive protocols, on the contrary, acquire routing information only when it is actually needed. However, the latency of the communication increases tremendously especially when a node communicates to another at the first time. Source routing vs. Hop-by-hop routing These two modes concern whether the source node decides the route for a packet to be forwarded to the destination or the intermediate nodes are allowed to decide the next hop until the packet arrives at the destination. In the source routing protocols, the source node decides the route and puts the route information in the packet header. All the intermediate nodes forward the packet along the route faithfully. This kind of protocols has advantage that the intermediate nodes are not required to maintain the routing information. But it suffers from the disadvantage that the packet size grows because of source routing information carried in each packet. In the hop-by-hop routing protocols, it is sufficient for the source to know only how to get to the next hop and intermediate nodes find their own next-hops until the destination. In contrast to source routing protocols, hop-by-hop routing protocols do not increase packet size but they requires all the intermediate nodes to maintain rout ing information. Table 2-1 Categories of routing protocols has compared the performance of these four routing protocols . The results show that DSR has best throughput performance (above 95%) at all mobility rates and movement speeds. Thus we will use DSR as basic routing protocol in this thesis. The Dynamic Source Routing Protocol (DSR) John et al. proposed the dynamic source routing protocol (DSR) [1] which is a routing protocol for use in multi-hop wireless ad hoc networks of mobile nodes. DSR is an ondemand protocol, in which route are only discovered when data need to be transmitted to a node where no route has yet been discovered. The advantage of this on-demand routing protocol is that there are not any periodic routing advertisement and reducing the routing overhead. DSR is also a source routing protocol, allowing multiple routes to any destination and allows each sender to select and control the routes used in routing the packets. DSR is composed of the two main mechanisms: Route Discovery and Route Maintenance which are explained below. Route Discovery Route Discovery aims at finding routes from a source node to destination. Figure 2-1 illustrates the procedure of Route Discovery. When a source node S wants to send a data packet to some destination node D, it first searches its route cache to find whether there is a route to D. If there is no route to D, then S will initiate a Route Discovery and send out Route Request message which is propagated to all the nodes within its transmission range. At the mean time, it saves the data packet in its send buffer. The Route Request message contains the addresses of source node and destination node, a unique route request identifier and a route record which records all the intermediate nodes that this route request packet has traveled through. S appends itself to the beginning of the route record when it initiates the message. When a node receives the Route Request message, it compares the destination address in the message with its own address to judge whether itself is the destination node. If it is not, it will append its own address in the route record and propagate the message to other nodes. If the node is the destination node, it will send a Route Reply message to the source node and the message contains the source route record which is accumulated when the Route Request message is forwarded along its way to the destination. When the destination sends the Route Reply, if it uses MAC protocols such as IEEE 802.11 that require a bidirectional link, it just reverse the source route record and use it as route to send Route Reply to the source node. Otherwise it should find the route by searching its route cache or sending out a Route Request which piggybacks the Route Reply for the source node. When the source node receives the Route Reply message, it puts the returned route into its route cache. From t hen on all the packets destined to the same destination will use this route until it is broken. Route Maintenance Since the ad hoc network is dynamic and the topology of the network changes frequently, the existing routes maintained by nodes in their route cache are often broken. After forwarding a packet, a node must attempt to confirm the reachability of the next-hop node. If the node does not receive any confirmation from the next hop during a certain period of time, it will retransmit the packet. If after a maximum number of retransmission it still does not receive any confirmation, it will think the link to the next hop is broken and will send a Route Error message to the source node. DSR proposes three acknowledge mechanisms to confirm that data can flow over the link from that node to the next hop: Link-layer acknowledgement which is provided by MAC layer protocol such as IEEE 802.11. Passive acknowledgement in which a node hears the next-hop node forwarding the packet and thus confirms the reachability of the link. Network-layer acknowledgement in which a node sends an explicit acknowledgement request to its next-hop node. Passive Acknowledgement Passive Acknowledgement (PACK) is important in DSR protocol because it is used to detect whether the next hop forwards the packet or drops it. We explain it in detail in this section. Passive acknowledgement is used with the assumption that: Network links operates bi- directionally. The network interface is in the promiscuous mode. When a node taps a new packet in promiscuous mode after it originates or forwards a packet, it consider it as an acknowledgement of the first packet if both of following check success. The Source Address, Destination Address, Protocol, Identification, and Fragment Offset fields in the IP header of the two packets MUST match. If either packet contains a DSR Source Route header, both packets MUST contain one, and the value in the Segments Left field in the DSR Source Route header of the new packet MUST be less than that in the first packet. If no matched packet is found during PACK timeout, the node will consider the link between the next hop and itself is broken and will send Route Error message to the source node. Additional features DSR has additional features such as replying to route requests using cached routes, caching overheard routing information, packet salvaging and flow state extension and etc. We will introduce them in section 4.1 and discuss how they will impact the performance of network, how they will interact with DSR and whether they will be enabled in our simulation. Performance Analysis Techniques This section introduces the performance analysis techniques and methodologies that will be used in the performance evaluation. Factors and Primary Factors There are many parameters that will influence the simulation results and need to be carefully chosen in the simulations. Some parameters are chosen based on experience values or the conditions of the network we want to simulate. Others need to be tuned to optimize the network performance. We distinguish the two kinds of parameters as follows: Factors are the variables that affect the simulation result and have several alternatives. Normally they are decided based on experience. Primary factors are the factors whose effects need to be quantified. This kind of factors usually needs to be adjusted through simulation. Data Measurement The key step of the network performance analysis is to interpret the simulation result and summarize the characteristic of the network. To avoid the inaccurate simulation results due to an extreme scenario, we usually run simulations on several different scenarios. The data set of these simulations are called sample. A single number must be presented to give the key characteristic of the sample and this single number is called an average of the data. There are three alternatives to summarize a sample Mean is obtained by taking the sum of all observations and dividing this sum by the number of observations in the sample. Median is obtained by sorting the observations in an increasing order and taking the observation that is in the middle of series. If the number of the observations is even, the mean of the middle two values is used as a median. Mode is obtained by plotting a histogram and specifying the midpoint of the bucket where the histogram peaks. Confidence Interval for the Mean In our performance evaluation, the main objective is to compare the simulation results of DSR and Standard DSR to see whether there is any performance improvement. However, most simulation results are random in some degree due to the particularity of the node movement scenarios and we cannot tell whether the two systems are different. One way to minimize the random effect is to repeat the simulations with different scenarios as many times as possible and get a large sample space. Unfortunately, due to the time limitation we cannot conduct many simulations. points out that using confidence interval we can tell whether the two systems are different with smaller sample space. The confidence interval for the mean can be calculated using If the confidence intervals of the simulation results of the two systems have no overlap, then we can claim the two systems are different and one system is superior or inferior to the other. GloMoSims source and binary code can be downloaded only by academic institutions for research purposes. Commercial users must use QualNet, the commercial version of GloMoSim. OPNET Modeler OPNET Modeler is commercial network simulation environment for network modeling and simulation. It allows the users to design and study communication networks, devices, protocols, and applications with flexibility and scalability [30]. It simulates the network graphically and its graphical editors mirror the structure of actual networks and network components. The users can design the network model visually.The modeler uses object-oriented modeling approach. The nodes and protocols are modeled as classes with inheritance and specialization. The development language is C. Comparison When choosing a network simulator, we normally consider the accuracy of the simulator. Unfortunately there is no conclusion on which of the above three simulator is the most accurate one. David Cavin et al. has conducted experiments to compare the accuracy of the simulators and it finds out that the results are barely comparable [31]. Furthermore, it warns that no standalone simulations can fit all the needs of the wireless developers. It is more realistic to consider a hybrid approach in which only the lowest layers (MAC and physical layers) and the mobility model are simulated and all the upper layers (from transport to application layers) are executed on a dedicated hosts (e.g. cluster of machines). Although there is no definite conclusion about the accuracy of the three network simulators, we have to choose one of them as our simulation environment. We compare the simulators using some metrics and the results are summarized After comparing the three simulators, we decide to choose ns2 as network simulator in our thesis because Ns2 is open source free software. It can be easily downloaded and installed. The author of the thesis has used ns2 in another network related course and gotten familiar with the simulation. Ns2 uses TCL and C++ as development languages for which the author has some programming experience. The author of the DSR protocol has conducted simulation on GloMoSim and gotten performance results. We want to do the simulation on a different simulation to form comparison. State of the Art In this chapter we will introduce the start of the art security solutions in MANET with emphasis on dynamic feedback mechanisms. Firstly, we will present the general security issues/requirements of MANET to pave the way for the future investigation. Then we will discuss the state of the art security mechanisms for MANET such as payment system,trust management system, reputation system, etc. Finally, we will summarize all the security solutions we discussed in this chapter. Security Issues in Mobile Ad Hoc Network Due to lack of central infrastructural and wireless links susceptible to attacks, security in ad hoc network has inherent weakness. In section 1.2 we have discussed the reasons why mobile ad hoc network imposes security challenges that cannot be solved by traditional security mechanisms. In this section, we present the general security properties required by ad hoc network. Following are general security properties regarding ad hoc network Confidentiality: The confdiantiality property is to protect certain information from unauthorized disclosure. The information includes not only the application data that send over the routing protocol, but also the routing information itself as well as network topology and geographical location. Integrity: The integrity ensures that the transmitted message and other system asset are modified only by authorized parties. In the routing level, it requires all nodes in the network following correct routing procedure. The main challenge of ensuring integrity is that without central infrastructure and powerful computing capabilities, it is difficult to apply existing cryptography and key management systems. Availability: The availability property requires that the services or devices are exempt from denial of service, which is normally done by interruption, network or server overload. Typical examples or denial of service attack are radio jamming, in which a misbehaved node transmit radio to interference other nodes communications, and battery exhaustion, in which a misbehaved node interact with a node for no other purpose than to consume its battery energy. Authentication: The authentication property requires that the communication entitys identification is recognized and proved before communication starts. Access control: This property requires restricting resources, services or data to special identities according to their access rights or group membership. Non-repudiation: This property ensures that when data are sent from sender to receiver, the sender cannot deny that he has sent the data and the receiver cannot deny that he has received the data. Mobile nodes may conduct different misbehavior for different purposes. Po-Wah Yau classifies the misbehaved nodes into following categories. Failed nodes are simply those unable to perform an operation; this could be because power failure and environmental events. Badly failed nodes exhibit features of failed nodes but they can also send false routing messages which are a threat to the integrity of the network. Selfish nodes are typified by their unwillingness to cooperate as the protocol requires whenever there is a personal cost involved. Packet dropping is the main attack by selfish nodes. Malicious nodes aim to deliberately disrupt the correct operation of the routing protocol, denying network service if possible. These four types of misbehaved nodes actually can be categorized in two aspects: whether their misbehaviors are intentional or unintentional, and the severity of the results. Payment Systems Payment systems provide economic incentives for the cooperation in MANET. They consider that each node in MANET is its own authority and tries to maximize the benefits it gets from the network. Thus each node tends to be selfish, dropping packets not destined to them but make use of other nodes to forward their own packets. The purpose of payment systems is to encourage the cooperation within the MANET by economic incentives. There are several variations of payment systems proposed. Nuglets Nuglets is a virtual currency mechanism for charging (rewarding) server usage (provision). Nodes that use a service must pay for it (in nuglets) to nodes that provide the service. A typical service is packet forwarding which is provided by intermediate nodes to the source and the destination of the packet. Therefore either the source or the destination should pay for it. There are two models for charging for the packet forwarding service: the Packet Purse Model (PPM) and the Packet Trade Model (PTM). In the Packet Purse Model, the sender pays for the packet. It loads the packet with a number of nuglets when sending the packet. Each intermediate forwarding node acquires some nuglets from the packet that covers its forwarding costs. If a packet does not have enough nuglets to be forwarded, then it is discarded. If there are nuglets left in the packet once it reaches destination, the nuglets are lost. In the Packet Trade Model, the destination pays for the packet. Each intermediate node buys the packet from previous one for some nuglets and sells it to the next one for more nuglets until the destination buys it. Either of the two models has advantages and disadvantages. While the Packet Purse Model deters nodes from sending useless data and avoids the network overloading, the Packet Trade Model can lead to an overload of the network and the destination receives packets it does not want. On the other hand, in the Packet Purse Model it is difficult to estimate the number of nuglets th at are required to reach a given destination. But thePacket Purse Model does not need to consider this problem. To take advantages of the two models and avoid the disadvantages, a hybrid model is suggested. In this model, the sender loads the packet with some nuglets before sending it.The packet is handled according to the Packet Purse Model until it runs out of nuglets. Then it is handled according to the Packet Trade Model until the destination buys it. Counter To address the problems encountered by the nuglets approach such as difficulty in estimating pre-load nuglets and possible network overload, another payment approach based on credit counter is suggested. In this approach, the current state of each node is described by two variables b and c, where b is the remaining battery power and cstands for the value of its nuglet counter. More precisely, b is the number of packets that the node can send using its remaining energy and c is the number of packets a node canoriginate. A node can originate a number of packets N only when the condition c=N holds. When a node forwards a packet, nuglet counter c is increased by one and b is reduced by one. Thus in order to originate packets, each node must earn credits by forwarding packets. The counter solution requires tamper resistant hardware security module. Spirit S. Zhong et al. proposed Sprite [19], a credit-based system for MANET. As opposed to Nuglets or Counter they do not require tamper-proof hardware to prevent the fabrication of payment units. Instead, they introduce a central Credit Clearance Service (CCS). The basic scheme of the system is as follows. When a node receives a message the node keeps a receipt of the message and reports to the CCS when the node has a fast connection to Credit Clearance Service (CCS). The CCS then determines the charge and credits to each node involved in the transmission of a message, depending on the reported receipts of a message. In this scheme, the sender charges money. A node that has forwarded a message is compensated, but the credit that a node receives depends on whether or not its forwarding action is successful. Forwarding is considered successful if and only if the next node on the path reports a valid receipt to the CCS. Discussion on the Payment Systems The payment systems we describe in above sections either assumes a tamper resistant hardware module is available to ensure that the behavior of the node is not modified or requires a central authority server to determine the charge and credit to each node involved in the transmission of a message. Tamper resistant hardware may not be appropriate for most mobile devices because it demands advanced hardware solution and increases the cost of the devices. Lacking of central authority server is right the inherent property of MANET that causes security challenges so it is also not appropriate. Furthermore, all the approaches described above suffer from locality problems [20] that nodes in different locations of the network will have different chances for earning virtualcurrency, which may not be fair for all nodes. Usually nodes at the periphery of the network will have less chance to be rewarded. Reputation System Reputation systems have emerged as a way to reduce the risk entailed in interactions among total strangers in electronic marketplace. Centralized reputation systems have been adopted by many on-line electronic auctions such as eBay to collect and store reputation ratings from feedback providers in a centralized reputation database. Decentralized reputation systems used by MANET, on the other hand, do not use centralized reputation database. Instead, in these reputation systems, each node keeps the ratings about other node and updating the ratings by direct observation of the behaviorsof neighboring nodes or second hand information from other trusted nodes. Identifies three goals for reputation systems: To provide information to distinguish between a trust-worthy principal and an untrustworthy principals. To encourage principals to act in a trustworthy manner To discourage untrustworthy principals from participating in the service the reputation mechanism is present to protect. Most of the reputation systems in MANET are based on trust management system. Trust is such a subjective and dynamic concept that different entities can hold different opinions on it even while facing the same situation. Trust management system can work without reputation system. For example, a mobile node can form opinion about other nodes by direct experience with the nodes.We can unify reputation system and trust management system to dynamic feedback mechanisms. Former one is a global reputation system and mobile nodes share their own experiences of interaction with other nodes. The later one is a local reputation system in which mobile nodes rating the trustability of other nodes based on its own observation. DSR DSR is a reputation system aiming at coping with misbehavior in MANET. The idea is to detect the misbehaved nodes and isolate them fromcommunication by not using them for routing and forwarding and by not allowing the misbehaved nodes to use itself to forward packets. DSR stands for Cooperation Of Nodes: Fairness In Dynamic Ad-hoc Network. It usually works as an extension to on demand routing