Causes effects and history of prostitution

Causes terminations and history of whoredomProstitution is listed among the crimes some refer to as victimless or consensual crimes, just research shows that may not be the true picture of whoredom. Before proceeding, we need to define prostitution. Despite of the fact that, prostitution being known as the oldest profession in the history of mankind. The workable definition has proven elusive. From a dictionary we learn that prostitution is the act or practice of engaging in windual intercourse for money. But a prostitute cannot simply be a woman who sells her body, since that was the norm of the society that wo workforce will get marriage in order to accomplish home and better life style. Promiscuity has been proposed as an separate candidate. Medieval canon lawyer Johannes Teutonicus suggested that a woman who had sex with more than than 23,000 men should be classified as a prostitute, although, furthermore he says that sexual intercourse with 40 to 60 opposite gender would al so be called prostitute. However, promiscuity itself does not turn a woman into a prostitute. Although a vast majority of prostitutes are promiscuous, most people would agree that sleeping about does not amount to prostitution. Hence I define prostitution as systematic sexual violence and oppression against female.Selected national and international research projects and versatile programs by women hasten been initiated to address the health burden of violence against women. Such projects have especially focused on the health consequences to women of battering or domestic help violence, rape and sexual assault, child sexual abuse and incest, and female genital mutilation (See, for example, World Bank Discussion Papers 255, Violence Against Women the Hidden Health Burden). In depicting the health effects of such forms of violence against women, these projects attempt to make the violence, harm and human rights violation to women visible. However, a consideration of the dire hea lth consequences of prostitution demonstrates that prostitution not only gravely impairs womens health but it is obviously violence against women. The health consequences to women from prostitution are the same injuries and transmittances suffered by women who are subjected to other forms of violence. The physical health consequences include injury (bruises, broken bones, black eyes, concussions). A 1994 study conducted with 68 women in Minneapolis/St.capital of atomic number 25 who had been prostituted for at least six months found that 50% of those women had been physically assaulted by their purchasers, and a third of those experienced purchaser assaults at least several times a year. 23% of those assaulted were beaten severely exuberant to have broken bones. Furthermore, 90% of the women in this study had experienced violence in their personal relationships resulting in miscarriage, stabbing, loss of consciousness, and head injuries (Parriott, Health Experiences of Twin Citie s Women apply in Prostitution).Prostitution is physically harmful to women. STDs (including HIV/AIDS, chlamydia, gonorrhea, herpes, human papilloma virus, and syphilis) are alarmingly high among women in prostitution. Only 15 % of the women in the Minneapolis/St. Paul study had never contracted one of the STDs, not including AIDS, most injurious to health (chlamydia, syphilis, gonorrheal, herpes). General gynecological problems, but in particular chronic pelvic pain and pelvic inflammatory disease (PID), plague women in prostitution. The Minneapolis/St. Paul study reported that 31% of the women interviewed had experienced at least one chance of PID which accounts for most of the serious illness associated with STD infection. Among these women, there was also a high incidence of positive pap smears, several times greater than the Minnesota Department of Healths cervical cancer screening program for low and middle income women. More STD episodes can increase the risk of cervical can cer. Another physical effect of prostitution is unwanted pregnancy and miscarriage. Other health effects include irritable bowel syndrome, as well as partial and permanent disability. The steamy health consequences of prostitution include severe trauma, stress, depression, anxiety, self-medication through alcohol and drug abuse and eating disorders. Almost all the women in the Minneapolis/St. Paul study categorised themselves as chemically-addicted. Crack cocaine and alcohol were used most frequently. Ultimately, women in prostitution are also at special risk for self-mutilation, suicide and homicide. 46% of the women in the Minneapolis/St. Paul study had attempted suicide, and 19% had tried to harm themselves physically in different ways, for example, in another survey of 55 victims/survivors of prostitution who used the services of the Council for Prostitution Alternative in Portland, Oregon, 78% were victims of rape by pimps and male buyers an average of 49 times a year 84% wer e the victims of aggravated assault and were thus horribly beaten, often requiring emergency room attention and hospitalization 53% were victims of sexual abuse and torture and 27% were mutilated (Documentation available from the Council for Prostitution Alternatives).In developing countries, it has also been estimated that 70 percent of female infertility is caused by sexually transmitted diseases that can be traced behind to their husbands or partners (Jodi L. Jacobson, The Other Epidemic, p. 10). Among women in rural Africa, female infertility is widespread from husbands or partners who migrate to urban areas, buy moneymaking(prenominal) sex, and bring home infection and sexually transmitted diseases. Women in prostitution industries have been blamed for this epidemic of STDs when in reality, studies confirm that it is men who buy sex in the process of migration who move the disease from one prostitute woman to another and ultimately back to their wives and girlfriends. The mo vement of abandoned or rejected barren women to urban prostitution has been document in Niger, Uganda, and the Central African Republic. Numerous studies in Africa and Asia by the World Bank and a number of international research organizations have found that part or separated women comprise the great majority of prostitutes or semi prostitutes (Jacobson, p. 13). Thus, a major health effect of the mass male consumption of commercial sex and the expansion of sex industries in developing countries is not only a rampant increase in sexually transmitted diseases but an exponential function increase in infertility. The further effects of this vicious cycle insure that a whole new segment of women who are abandoned by their husbands imputable to infertility, are propelled into prostitution for survival. In both developing and industrialized country contexts, underway campaigns to control the spread of HIV/AIDS by advocating safe sex for women in prostitution fail to address the blatant inequities between women who are bought for sex and the men who pay for it. Any AIDS strategy based on negotiating condom use between the purchaser of sex and the woman who must supply it assumes symmetry of power that does not even exist between women and men in many personal consensual relationships. If AIDS programs are serious about eradicating AIDS, they must challenge the sex fabrication.Women in prostitution are targeted as the problem instead of making the sex industry problematic and challenging the mass male consumption of women and children in commercial sex. This is institutionalized when governments and NGOs argue for the medicalization of prostitution when they propose laws on prostitution which subject women to periodic medical check-ups. It is stated that women in the sex industry would be better protected if they submitted, or were demand to submit, to health and especially STD screening. The way in which sex industries are responsible for the widespread health p roblems of women and children is mystified with proposals to implement health checks of women in the industry. No proposals have been forthcoming, from those who would propose both mandatory and voluntary medical surveillance for women in the sex industry, to medically proctor the men who would purchase sex. The same is true with current attempts to medicalize prostitution. No action will stabilize the sex industry more than legitimating prostitution through the health care system. If medical personnel are called upon to monitor women in prostitution, as part of occupational health safety, we will have no hope of eradicating the industry. Furthermore, from a health perspective alone, it is inconceivable that medicalization of women in the industry will reduce infection and injury without concomitant medicalization of the male buyers. Thus medicalization, which is rightly viewed as a consumer protection act for men rather than as a real protection for women, ultimately protects neith er women nor men.As with other forms of violence against women eradicating the health burden of prostitution entails addressing but going beyond its health effects. To address the health consequences of prostitution, the international human rights community must understand that prostitution harms women and that in addition to needing health services women must be provided with the economic, well-disposed and psychological means to leave prostitution. Until prostitution is accepted as violence against women and a violation of womens human rights, the health consequences of prostitution cannot be addressed adequately. Conversely, until the health burden of prostitution is made visible, the violence of prostitution will remain hidden. Once Victor Hugo quotes stated in is novelWe say that slavery has vanished from European civilization, but this is not true. Slavery still exists, but now it applies only to women and its name is prostitution.

Why companies sometimes face difficulties in raising finance

Why companies sometimes face difficulties in raising financeTopic Explain what sources of finance are available for small to medium sized companies and explain why they sometimes face difficulties in raising financeIntroductionDue to the establish of modern effort system and soundly in structural reforms of commercialise economy, there are lot of opportunities contained in the market, but it is also existing many unexpected take a chances, particularly for the small to medium-sized enterprise (SMEs) which has limited resources to resist in this treacherous purlieu. To survive and adapts to the environment for a SME is to maintain its advantage in meticulous daily management and even much important is to have a long-term view strategic call ining especially in pecuniary strategy. A good finance strategy whoremaster inspection and repair SME to set up and expand their operations, development and also coronation (OECD, 2006), further to get funds which make them competitivel y and crapper get rise up results they desired (Park, 2010). Making a finance strategy is very significant to a bon ton company has to consider both of internal condition and international environment trouble and even more factors which are cerebrate to company. However, the SME has its particular characteristic, it is non fitted to adopt the same action with a large company they better to create a strategy which fits to the company according to its demand. Finding a proper financial strategy for a developing SME, not exactly can help SME to reinforce its essence, the more important is the sustain great power of its development.Define companyThere is no accurate interpretation for small to medium-sized enterprise (SMEs) and most of countries square off it according to specific condition by their way. Nevertheless, there are some particular characteristics (Bank of England, 2001 Brookfield, 2001) about SMEs and they areThe enterprises are not quotedOwnership is often comm itted between family and shareholder and the business is typically restricted to few individuals.Most of SMEs are small groups business and always achieve self-employment effectively.In the past, the definition for SMEs from European Commission was unequivocal, it was defined by individual country, for instance, Germany regulated the amount of employee under 250 was part of SME, but in Belgium, the number was became 100. However, in the recent years, the data from European Commission shows that the definition has adjusted and is qualified as a SME by some criteria (see figure 1-1) (European Commission, 2010) in headcount, turnover and eternal rest sheet total.Figure 1-1 the definition of a small firm from European CommissionImportance of financeNowadays, the enterprises finance is facing a dynamic, diversification and complicated managing environment. Managing finance is not unaccompanied to provide a specific rule or device for a firm it is to assimilate the principle and manner from strategic management. Start from the view of adapting to the environment and using the vantage, to pay much attention in financial long-term problem and strategic problem. In the situation of lacking of the resources for SME, to create a suitable financial strategic and well dominate the limited resource is significant since a better financial systems can help to amend the probability of boffo innovation and bring accelerate economic growth.(King, et al., 1993)The focus of enterprises financial strategy is the basic path on future development, goal and goal accomplishment for the financial action this is the difference between financial strategy and other strategies. The master objective of enterprises financial strategy is reasonably to assemble, dominate and use its resources, tend to balance and flow enterprises detonator, also to build the essence competitive strength and to achieve the maximization of enterprise value in the end. Some aspects of this goal are related/ connected to each other from the view of a long-term performance, to seek the enterprises sustainability growth in financial resource and capability, and furthermore to accomplish the rising of enterprises outstanding value and make enterprises financial capability can sustained, quick and healthily increase, conduce to maintain and develop enterprises competitive advantage.While enterprise building the core competitive strength for their strategic management, they need the support from financial management. The financial management which treats groovy management as a significant content, it demand to extend the requirement for enterprises strategy and to guarantee its practice. The value of practicing the financial strategy is to retain a health condition in enterprises finance and also effectively in controlling the financial risk.There are twelve types of pay and growth in SMEs and it can be very usefully and provided a great help if it is supplied properly according to SME s particular requirement (Brookfield, 2001).Initial owner finance (Equity finance)Business angel fundingTrade creditLeasingFactoring approximate jacketShort-term bank adds (Debt finance)Medium term bank loansMezzanine financePrivate arrangingsPublic equityPublic debtA company should manage its financing structure in a way that its debt and equity are in balanced manner. This fact helps company to avoid insolvency. Excess of either debt or finance could result in loss of wealth. I will be explaining some of the important methods of financing in following section.Equity financeEquity financing is that the shareholder sells the part of corporate control to introduce the new shareholder by raising the uppercase (Watson, et al., 2007). The enterprise does not need to pay the please on pass if the capital is received from equity financing and the new shareholder can share the profit from enterprise as well. Equity financing includes stock issuance, allotment and debt for equity sw ap. Some features of equity financing, areStock equity is firms first right of its property, it is the base for enterprise to absorb the civil obligation and to responsibility for firms own profits and losses furthermore, it is also the base for investor to control the enterprise and to distribute the profit.Equity financing is the base of deciding an enterprise to the outward debt.Certainly, there are some advantages of equity financing that help enterprise in investment and management.Equity financing builds a good system in corporate governance structure, which consists of shareholders meeting, board of directors, Board of supervisors and executives. It is effectively in decreasing the risk of management.In the modern finance theory, stock market is also called on the barren(p) market it means that the standardization financial products are dealing in a trading area with an extensively institutionalization. It has its criterion and processes it in the condition of discipline revelation and fare dealing. In financial translation, the more important is publicity and availability of information and that is why the stock market is better than loan market in both competitiveness of capital price and publicity of information.Venture capitalVenture capital is the fund which is collected by private placement and set as the type of organization invest to unlisted small and medium-sized newly emerging enterprises and in the capital type of both high risk and high reciprocation. Venture capital is different from mutual fund, unit trust and securities investment fund it has its features in operating of investment and collection, such as,Venture capital absorbs the reckon with enterprise the venture capitalist needs to cooperate closely with entrepreneur and help the firm to make a plan. Management is part of investment.Venture capital is an investment in long-term and poor flowability venture capitalist and entrepreneur become a common destiny once they invest.Ve nture capital is high risk and requires the venture capitalist with specialized skill, and need to achieve specialization and programmed in choosing the project, tend to avoid the risk.Before inspect the financial index, the venture capitalist pays more attention in market prospect, development strategy and managing quality.Sharing the bonus from enterprise is not the purpose of venture capital, they make it as a return by increasing the capital when they are exiting the time for exiting is always when go on public or sell it.Debt financeDebt financing is also called bond financing, it is the way which the firm can raise money for enterprises external finance and debt can also be conducted and fitted to the requirement of issuing companies and investors (Watson, et al., 2007). It is include long-term bank loans, short-term financing (such as bills, debt receivable, and letter of credit), enterprise Bond and short-term financial bonds, also long-term bond financing, finance lease, d isplace government loans, government loan, Loans from international financial organizations and private bond fund.The first expense enterprise needs to pay is the interest of capital which receives from debt financing and the principal on the debt will be paid to creditor at maturity (Davis, et al., 1994). The feature of purpose for debt financing is to solve the problem of deficiency in working capital rather than the expenditure under the capital account. Debt financing can be described by two features,The received capital from debt financing is only for using, it is not the property of the enterprise, and the firm needs to pay interest and the principal is repayable.Compare to equity financing, except some specific situations that debt financing may bring creditor the problem of intervention or controlling, otherwise it is barely to have the problem of corporate control.However, debt financing has its advantage for helping the firm in investment and management,The lenders have ab ility to collect and analyze the states of investment, also can have long-term investigate and oversee the enterprise to avoid the moral hazard.The function of the creditors right is when firm can pay off the debt, the firm will hold the corporate control, whereas of the enterprise cannot offer the debt, the corporate control will be turned to lender.Why do SMEs find financing a problem?Due to SMEs small size capital, the capability for defending the market risk is not as strong as a large firm, plus a faulty finance system, it causes the problem into SMEs finance management (Pissarides, 1999). The main reasons and problem areNo criterion in SMEs finance accounting systemIn application of finance system in SME exist some problems, which make loose financial control. A loose inventory control can lead to the stagnation of capital and excessive final inventory the capital of final inventory always in a high proportion if compare to sale revenue. The firm usually loses a large number o f assets due to focus on capital much more than assets and even wastes it seriously moreover, to control the finished products, semi-manufactured goods and low-value expendable without a faultless system.It is negligent in managing the cash and weakness in debt receivableSome of enterprises think that it is good to hold cash (including bank deposit), and better to have more the proportion of reserve is too high, it makes lot of capital cannot really run in operation, and also causes the capital idleness. In addition, some firms invest too much in real estate and lead to finance difficulty due to could not handle the emergent need of management. Also deficiency in managing working capital creates problems problem capital withdrawal.Difficulty in funding, the capital is insufficientIt is not easy to run the SME in a practically environment, especially the unequal treatment in funding between SME and larger enterprise. The banks are not instinctive to loan to them, particularly the di fficulty in guarantee and lack of the specialized agency to offer the assurance service is still the main problem for SME and it patently happens in some huge investments.Unrestraint in investmentThe SME is lacking of the ability to analyze the investment accurately and to evaluate the effectiveness of operating the capital. The majority of investment in SME is from banking, due to the respectability of a SME is not as high as a large company, it is an obstacle in attracting the banking to invest or loan to the SME.The mode of management is retrospectiveMost of SME is running the business as a family workshop they are operation the management in a backward way and an old-fashioned thinking way, do not understand and even not willing to understand or learn the modern financial management. The proprietor always treats the enterprise as an extension of familys property in order to control the business entirely without decentralize the ownership, it causes the lost of the opportunitie s in growing.ConclusionSMEs impart an important role in the general macroeconomic environment, and provide the enormous opportunities for employment. However, due to the small size and limited source, usually SMEs has to face to the challenge in financing problem. For solving the problem, the major impact is from government and the law (Industrial Systems Research). In existing policy has to be adjusted by government the government needs to reinforce the related law and regulation to implement SMEs development strategy and preferential clause. Furthermore, have to set up the institution for managing and supporting SMEs development. To increase the method for financing SMEs need to respect the debt from bank and to pay back the debt on time then to healthy the internal system and raise the handling of material. Lastly, to improve accountants structure and criterion of financial management enhance the punishment for the illegality to makes they pay attention in financial system.

Mobile Ad Hoc Networks (MANETs)

wandering Ad Hoc intercommunicates (MANETs)IntroductionWhat is Mobile Ad Hoc profit?With rapid development of wireless technology, the Mobile Ad Hoc Ne twainrk (MANET) has emerged as a new type of wireless profits. MANET is a collection of wireless wide awake bosss (e.g. laptops) that energizing tout ensembley sound as a interlocking without the occasion of any(prenominal) animate infrastructure and centralize administration. It is an autonomous dust where distri scarceively guest operates non just as an end system but overly as a despatchr to forward sheafs for separate lymph glands.Since the nodes in MANET move around, the wireless links assault and re-establish frequently. Furthermore, intimately of diligent nodes atomic figure of speech 18 re come p machinationicular(a) in reckoning capability and outpouring force play and at that placefore handed-d decl atomic number 18 computing content routing colloquys protocols ar not adapted for MANET. S everal ad hoc routing protocols acquit been proposed for separately node acting as wayr and maintaining routing discipline. there argon more new(prenominal) applications of MANET. For examples, MANET screwing be employ to provide emergency Services when the net profit is impaired due to the damaging of existing infrastructure 8. Computer scientists pitch predicted a world of give way computing in which computers provide be alone around us, constantly arrangeing mundane tasks to render our lives a little easier. These ubiquitous computers connect in spry ad hoc mode and change the purlieu or react to the change of the environment where they be suited. MANET is also found useful in the altogethereged(prenominal) sensor dust intercommunicate to coordinate the activities and reports of a large collection of tiny sensor devices which could offer detailed learning intimately(predicate) terrain or environmental dangerous stipulations.Problem Statement and Motivat ion to the highest degree current ad hoc routing protocols assume that the wireless net income is benign and every node in the ne twork strictly follows the routing behavior and is leave behinding to forward sh atomic number 18s for other nodes. Most of these protocols cope well with the propelling in eachy changing topology. However, they do not finish the problems when misbehavior nodes present in the network.A comm besides observed misbehavior is share dropping. In a practical MANET, most devices have very limited computing and assault and battery part while packet advancement devastates a attraction of much(prenominal)(prenominal) re fenders. indeed 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 light upon 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 measuredly by the misbehaved nodes or dropped due to the node having go out of transmission range or other link error. sheaf drop significantly decreases the network functioning.Traditional protective covering mechanisms are generally not suitable for MANET becauseThe network lacks central infrastructure to apply traditional security mechanism such as entry control, authentication and indisputable 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 mustinessiness be found.Network topologies and memberships are constantly changing. and then new intrusion detection system and entity recognition mechanisms that are suitable for mobile ad hoc networks must be designed to parry or extenuate the behavior to the networks.Trust management systems have been recently wrapd as a security mechanism in MANET. In a avow management system, a communicating entity collects demonstrate regarding competence, honesty or security of other network participants with the calculate of making legal opinion or decisions regarding their trust relationships. Here trust quarry and Sub-tasks sozzleds the self-assurance of an entity on another entity establish on the expectation that the other entity impart perform a particular action important to the trustor, disregardless of the ability to monitor or control that other entity . For example, a trust- ground routing protocol can collect the express of nodes misbehaving, form trust apprizes of the nodes and select safest paths establish 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 base not only on the selfobserved evidence but also on the second hand information from third parties. One of the influential reputati on systems is the DSR protocol. In the trust management system, reputation system and other trust-based systems, route selection is based on the direct 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 management systems and their derivations as dynamic feedback mechanisms. The dynamic feedback mechanisms are ordinarily 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-tasksThe primary accusative of this dissertation is to Investigate the state of the art of dynamic feedback mechanisms and protocols analyz e, weapon and evaluate DSR protocols to see how it improves the network exertion and what are the side powers of introducing the mechanism to the mobile ad hoc network.Following tasks must be done to achieve the primary objective.Study the preliminary association that is ask to carry out the main tasks. For example, to agnise DSR protocol one must have some knowledge of Bayesian analysis to do mathematical operation analysis one must learn the methodologies of takeing exploit analysis and processing disguise selective information.Investigate security issues of mobile ad hoc network and current dynamic feedback mechanisms or protocols that are use to solve or mitigate the issues.Investigate and learn how to use the network simulation tool. There are several commonplace network simulation tools available and we want to hold the one that best suits our needs. The selected network simulator should be studied so that we can use it as plan to implement protocol and conduct s imulations.Analyze and implement the DSR protocol based on Dynamic acknowledgment Routing protocol (DSR) evaluate the network performance.Structure of the underwriteSince we have almost gone through the chapter one, we only briefly present the content of the subsequent chapters in this incision.Preliminary InformationState of the Art epitomeDesignImplementation and Tests PerformanceAnalysis demonstration and Future WorkPreliminary informationwe have introduced the MANET. This chapter presents other preliminary information and concepts that leave behind be used in other parts of the thesis. foremost iv general modes of routing mathematical processs are introduced and differentiated. 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 perf ormance analysis are presented. Finally, several pop network simulation tools are discussed and compared.Mobile Ad Hoc Network Routing ProtocolsNowadays there are confused routing protocols proposed for the MANET. The most popular ones are DSDV (Destination-Sequenced Distance Vector), TORA (Temporally- legitimate Routing Algorithm), DSR (Dynamic Source Routing) and AODV (Ad-hoc On Demand Distance Vector). These routing protocols can be categorized in opposite routing operation modes.Mode of Routing OperationsThese two modes concern whether or not nodes in an ad hoc network should keep track of routes to all possible addresss, or instead keep track of only those destinations of immediate occupy Proactive protocols store route information even before it is needed. This kind of protocols has advantage that chats with exacting 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 staggeringly especially when a node communicates to another at the first time.Source routing vs. Hop-by-hop routingThese two modes concern whether the etymon node influences the route for a packet to be forwarded to the destination or the mediocre nodes are allowed to decide the near 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 on 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 bec ause 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 cling to the next hop and intermediate nodes find their induce 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 routing information.Table 2-1 Categories of routing protocolshas 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 allow 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 t o 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 maneuverer to select and control the routes used in routing the packets. DSR is composed of the two main mechanisms dispatch Discovery and travel guidebook Maintenance which are explained below. alley Discovery track Discovery aims at finding routes from a source node to destination. Figure 2-1 illustrates the procedure of passage Discovery. When a source node S wants to send a data packet to some destination node D, it first searches its route compile 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 outRoute Request core which is propagated to all the nodes within its transmission range. At the mean time, it saves the data packe t in its send buffer. The Route Request gist 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 sustain address to count on 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 retort 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 r everse 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 displace 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 then on all the packets destined to the same destination will use this route until it is broken.Route MaintenanceSince 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 transport a packet, a node must attempt to fix the reachability of the next-hop node. If the node does not receive any substantiation from the next hop during a certain period of time, it will retransmit the packet. If after a utmost 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 erroneousness 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 hopLink-layer acknowledgment 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 thence confirms the reachability of the link.Network-layer acknowledgement in which a node sends an lucid acknowledgement request to its next-hop node.Passive AcknowledgementPassive 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 thatNetwork links operates bi- directionally.The network interface is in the wanton mode. When a node taps a new packet in promiscuous mode after it originates or forwards a packet, it bring it as an acknowledgement of the first pac ket if both of following check success.The Source Address, Destination Address, Protocol, Identification, and Fragment first-class honours degree 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 lot the link between the next hop and itself is broken and will send Route Error message to the source node.Additional featuresDSR has additional features such as replying to route requests exploitation 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 mend the performance of network, how they will interact with DSR and whether they will be enabled in our simulation.Performance Analysis Te chniquesThis section introduces the performance analysis techniques and methodologies that will be used in the performance evaluation.Factors and Primary FactorsThere 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 strike the two kinds of parameters as followsFactors 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 MeasurementThe mark step of the network performance analysis is to figure the simulation result and summarize the feature film of the network. To avoid the in spotless 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 name characteristic of the sample and this single number is called an average of the data. There are three alternatives to summarize a sample symbolize is obtained by taking the sum of all observations and dividing this sum by the number of observations in the sample. median value 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 MeanIn 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 resul ts are ergodic in some degree due to the distinctiveness 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 time as possible and get a large sample space. Unfortunately, due to the time limitation we cannot conduct many simulations. points out that using confidence musical 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 wanting(p) to the other.GloMoSims source and binary code can be downloaded only by academic institutions for research purposes. commercial-grade users must use QualNet, the commercial version of GloMoSim.OPNET modelerOPNET patterner is commercial network simulati on 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 reflect 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 speech is C.ComparisonWhen choosing a network simulator, we normally consider the accuracy of the simulator. Unfortunately there is no last 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 t o consider a hybrid approach in which only the lowest layers (MAC and physical layers) and the mobility model are fictive 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 drive one of them as our simulation environment. We compare the simulators using some metrics and the results are summarizedAfter canvas the three simulators, we decide to choose ns2 as network simulator in our thesis becauseNs2 is open source free software. It can be easily downloaded and installed.The author of the thesis has used ns2 in another network cogitate 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 simulatio n on a different simulation to form comparison.State of the ArtIn 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 forthcoming 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 NetworkDue 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 prop erties regarding ad hoc networkConfidentiality The confdiantiality place 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 geographic 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 run or devices are exempt from denial of portion, which is normally done by interruption, network or innkeeper overload. Typical examples or denial of service attack are radio jamming, in which a misbehav ed 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 main course in effect(p)s 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 only when those unable to perform an operation this could be because power failure and environmental events.Badly failed nodes exhib it 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 self-serving 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 SystemsPayment systems provide economic incentives for the cooperation in MANET. They consider that each node in MANET is its own confidence 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 e ncourage the cooperation within the MANET by economic incentives. There are several variations of payment systems proposed.NugletsNuglets is a virtual currency mechanism for charging (rewarding) server practice (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 precedent (PPM) and the Packet mass Model (PTM).In the Packet Purse Model, the sender pays for the packet. It loads the packet with a number of nuglets when direct 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 move 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 aim the number of nuglets that 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 ou t of nuglets. Then it is handled according to the Packet Trade Model until the destination buys it.CounterTo 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 expound 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 wicked computer ironware security module.SpiritS. 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 equivocation 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 energize 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. send on is considered successful if and only if the next node on the path reports a valid receipt to the CCS.Discussion on the Payment SystemsThe payment systems we describe in above sections either assum es 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 jeopardizes 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 SystemReputation systems have emerged as a way to reduce the risk entailed in interactions among total strangers in electronic marketplace. centralise 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 update the ratings by direct observation of the behaviorsof neighboring nodes or second hand information from other trusted nodes. Identifies three goals for reputation systemsTo provide information to distinguish between a trust-worthy principal and an untrustworthy principals.To encourage principals to act in a trustworthy meansTo 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 intrinsic and dynamic concept that different entiti es can hold different opinions on it even while confront 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 merge reputation system and trust management system to dynamic feedback mechanisms. Former one is a spherical 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.DSRDSR is a reputation system aiming at coping with misbehavior in MANET. The idea is to detect the misbehaved nodes and impound 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 routingMobile Ad Hoc N etworks (MANETs)Mobile Ad Hoc Networks (MANETs)IntroductionWhat 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 MotivationMost 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. Howe ver, 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 becauseThe network lacks central infrastructure to apply traditional security mechanism such as access control, authenti cation 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 trustObjective and Sub-tasksmeans 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, irrespe ctive 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 management systems and their derivations as dynamic feedback mechanisms. The dynamic feedback mechanisms are usually applied on the current ad hoc routing protocols to r ate 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-tasksThe 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 performan ce 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 ReportSince we have almost gone through the chapter one, we only briefly present the content of the subsequent chapters in this section.Preliminary InformationState of the ArtAnalysisDesignImplementation and Tests PerformanceAnalysisConclusion and Future WorkPreliminary informationwe have introduced the MANET. This chapter presents other preliminary infor mation 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 ProtocolsNowadays 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 OperationsThese 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 routingThese two modes concern whether the source node decides the route for a packet to be forwarded to the destination or the intermediate nodes are allowe d 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 routing information.Table 2-1 Categories of routing protocolshas 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 DiscoveryRoute Discovery aims at finding routes from a source node to destination. Fi gure 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 outRoute 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 propag ate 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 then on all the packets destined to the same destination will use this route until it is broken.Route MaintenanceSince 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 hopLink-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 AcknowledgementPassive Acknowledgement (PACK) is important in DSR protocol because it is us ed 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 thatNetwork 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 featuresDSR 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 TechniquesThis section introduces the performance analysis techniques and methodologies that will be used in the performance evaluation.Factors and Primary FactorsThere 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 followsFactors are the variables that affect the simulation result and have several alternatives. Normally they are decided b ased 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 MeasurementThe 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 sampleMean 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 tw o 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 MeanIn 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 ove rlap, 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 ModelerOPNET 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.ComparisonWhen choosing a network simulator, we normally consider the accuracy of the simulator. Unfortunately there is no conclu sion 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 summarizedAfter comparing the three simulators, we decide to choose ns2 as network simulator in our thesis becauseNs2 is open source free software. It can be easily downloaded and install ed.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 ArtIn 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 NetworkDue to lack of central infrastructural and wireless links susceptible to at tacks, 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 networkConfidentiality 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 SystemsPayment systems provide economic incentives for th e 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.NugletsNuglets 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 that 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.CounterTo 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.SpiritS. 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 th e 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 SystemsThe 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 e arning 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 SystemReputation 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 systemsTo provide information to distinguish between a trust-worthy principal and an untrustworthy principals.To encourage principals to act in a trustworthy mannerTo 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.DSRDSR is a reputation system aiming at coping with misbehavior in MANET. The idea is to detect the misbehaved nodes and iso late 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

Information and Comunication in The Truman Show :: essays research papers

NDICEIntroduccin2Ficha Tcnica..3Sinopsis4Ficha Artstica.5Anlisis de los usos de la informacin y la comunicacin...9Bloque I Informacin como cambiante de situacin.10Bloque II Informacin como poder.25Bloque III Concepto de comunicacin / Comunicacin Interpersonal...31Conclusin.61Bibliografa62INTRODUCCINEl objetivo en este trabajo es aplicar a una pelcula las teoras aprendidas sobre informacin y comunicacin. El primer problema al que hay que afrontarse cuando se decide realizar este trabajo es qu pelcula ser el objeto de nuestro anlisis. Yo afront este problema siguiendo el siguiente criterio encontrar una pelcula donde pudiera aplicar de forma clara las teoras aprendidas en clase y que no se tratase ni de una pelcula que me disgustase, ya que entonces me resultara imposible trabajar con ella, pero que tampoco fuese una pelcula que me encantase porque tema acabar saturada de ella. Escog El Show de Truman porque un da haciendo zapping vi la mitad de la pelcula, y sin darme cuenta estaba i ntentando ver y aplicar las teoras que habamos estado dando en clase. A continuacin expongo paso por paso un anlisis sobre los usos de la informacin y de la comunicacin en El Show de Truman.FICHA TCNICAAo1998Estreno 30-10-98Gnero ComediaDuracin 102 min.Ttulo realThe Truman ShowDirector Peter WeirIntrpretes Jim Carrey (Truman Burbank)Laura Linney (Meryl Burbank/Hannah gill)Noah Emerich (Marlon/ Louis Coltrane)Natascha McElhone (Lauren Garland/Sylvia)Ed Harris (Christof)Holland Taylor (Madre de Truman)Guion Andrew NicolFotografa Peter BizouMsica Philip GlassBurkhart von DallwitzMontaje William M. AndersonSINOPSISTruman Burbank es el protagonista de un programa de mxima audiencia que se emite durante las 24 horas al da. El pueblo en el que vive es un decorado y la gente que le rodea son todos actores. A medida que avanza la pelcula Truman comienza a sospechar sobre la naturaleza de su vida. Una vez descubre la verdad se enfrenta a Christof, director y creador del programa.FICHA ARTSTI CAJim CarreyNombre real Jim CarreyNacionalidadCanadienseLugar Newmarket, Ontario, CanadaFilmografaOlvdate de mi (2004) Una serie de catastrficas desdichas de Lemony Snickets (2004) Como Dios (2003) The Majestic (2001)El Grinch (2000)Yo, yo mismo e Irene (2000)Man on the Moon (1999)El show de Truman (1998)Mentiroso compulsivo (1997) Un loco a domicilio (1996)Batman Forever (1995) Ace Ventura II. Operacin Africa (1995)Dos tontos muy tontos (1994) La mscara (1994) Ace Ventura, un detective diferente (1993) (Actor y Guionista) El cadillac rosa (1989) La lista negra (1988) Peggy Sue se cas (1986) Mordiscos peligrosos (1985)Presentando a Janet (1983)Ed HarrisNombre real Ed Harris Nacionalidad EE.UU.Lugar de nacimiento Englewood, NJFilmografaMe llaman Radio (2003)

American Women Liberation :: essays research papers

Did WW II Liberate American Women?World War II did liberate American Woman .After pearl harbor,in fact ,employers openly support women to join the industrial labor pool.By 1947, 37percent of all adult in United States were inwork force.Married women represented over 70 percented of the increase in young-bearing(prenominal) employees,a significant shift away from traditional patterns in which the vast majority of working women had been young and single.It has also been criticized that they lost their job right after the war was ended. But not all of them lost their jobs. Lots of them who desired to continue to work held their positions safe.As they had already paved their way towards employment, it wasnt difficult for them to work in disparate places they havent woked out front.The most significant change that WW II brought in American Women is the endof sex segregation in work force.Prior, they were allowed to do some so called female jobs and live life as housewives. But duri ng world war II they were employed in different manufacturing jobs and the work they performed challanged prevailing definition of womanhood.Black women were able to benifit more(prenominal) from WW II. Before the war the majority of opprobrious women were relegated to the whte womanskitchen.In 1940, two-third of employed black women worked as domestic in LA.By 1950, this proportion dropped to 40% and was accompained by an increase ofblack women in durable maufacturing.Different criticism had been made that womenhad to quit their jobs to make space available for men who returned from the war.But the war had changed the perspective of nature of work that women were intobefore the war.The war had women more freedom than they had ever had before.

Zora Neale Hurston - Their Eyes Were Watching God :: essays research papers

Their Eyes Were Watching matinee idolIt is human nature to opine for happiness. Some people find it in material possessions, some find it in money, but most of us find it in love. To find square(a) love is a difficult task especially now in the times of cell phones and Jaguars. Money and power play a big character in todays society, and some people would rather have those things than a love of a nonher human being. In some rare cases it is not even a persons decision who she (almost every time its a woman who is being given away) will marry. Although it does not come very often, there are still cases where a woman is being married off to a man by an arrangement made by her parents, to insure stability and security of that woman. The standing in the community means a great deal, just like Zora Neale Hurstons Their Eyes Were Watching God illustrates. Janie, the main character in the book, was raised by her grandmother. Ever since Janies mother ran away it was just the two of them living together. As a squirt Janie lived in the house where her grandmother was a nanny for a white family. She was treated the same as the white children, they ate together, played together, even got penalize together. Janie, unlike most of the blacks at that time, did not see any discrimination while she was growing up. That was the building block of her strong personality. There was some vamp in school about her living in a white folks home, but she did not pay much attention to that. Now if I may go off the subject for a moment I would like to say how beautifully and descriptively the book is written. There is one expiration in particular that I truly enjoyed reading It was a spring afternoon in West Florida. Janie had spent most of the day under a blossoming pear tree in the back-yard. She had been spending every minute that she could steal from her chores under that tree for the last three days. That was to say, ever since the first exact bloom had opened. It had called h er to come and gaze on a mystery. From barren brown stems to glistening leaf-buds from the leaf-buds to snowy virginity of bloom. It stirred her tremendously. How? Why? It was like a flute vociferation forgotten in another existence and remembered again.

Use of Theme, Setting, and Time in Ibsens Hedda Gabler Essay -- Hedda

Use of Theme, Setting, and Time in Hedda Gabler Hedda Gabler, by Henrik Ibsen, is a work about a wo human being who manipulates the fates of others in gear up to fulfill her own desires. The title character is a woman who has recently returned from a six month honeymoon with her groom, Tesman, a man whom she does not love. She yearns for freedom, merely she feels as if she cannot leave her marriage. To occupy her time, she manipulates the lives of everyone around her. Hedda kills herself after becoming engorged in her own manipulations. Through the use of theme, setting, and time period, Ibsen produces a work that unambiguously portrays the sources of the motivations of this manipulative woman. Whether it be the burning of her former loves manuscript or supplying him with the pistol to shoot himself, Heddas malevolence shows the ability of man to have total disregard for the life of another. Hedda coldly manipulates the lives of everyone around her. Through these manipulative a ctions, she ruins the lives of all of her acquaintances. Because she is not happy in her marriage, she attempts to forbid anyone else to live a content life. For example, after she persuades Eljert Lvborg to consume alcohol, he ruins his reputation and loses something that is most precious to him the manuscript of a book that he had been writing with Mrs. Elvsted. Although Hedda realizes the importance of this manuscript to both Lvborg and Mrs. Elvsted, she chars it. Because Lvborg and Mrs. Elvsted have put their souls into this manuscript, Hedda metaphorically relates her action to burning their child. This cold thoughtlessness demonstrates Heddas disregard for the life of a ally human being. Heddas actions ultimately lead to her demise. After giving ... ...nnot manipulate her own life. She does not want to remain in her marriage, but she lacks the courage to repel out of it. Because of the times and her situation, she feels that she cannot leave her husband. It seems as if thes e manipulations are a sick form of entertainment for Hedda. One could regard this play as a stringently feminist work or as the story of a woman who has no regard for human life. In either way in which it is regarded, Ibsen realistically portrays the motivations of Hedda Gabler through his use of theme, setting, and current events. Works Cited Hemmer, Bjorn. The dramatist Henrik Ibsen. http//odin.dep.no/ud/nornytt/ibsen.html Ibsen, Henrik. Four Major Plays A Dolls House, Ghosts, Hedda Gabler, The Master Builder. New York Oxford University Press, 1998. Mazer, Cary M. Hedda Gabler. http//www.english.upenn.edu/cmazer/hedda.html.