<p>The usage of Wireless Local Area Networks is increasing rapidly throughout the world. The technology today is not quality proof for the market’s demands. We want to be able to completely wireless perform our demands, such as confer via video or IP-telephony. This is what we call multimedia real-time traffic. It may be achieved over the physical infrastructure in some areas with good results. The goal of this Master’s Thesis is to analyze the possibilities and give solutions and suggestions to achieve multimedia over the wireless networks, with emphasis on the protocol Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). </p><p>This Master’s Thesis is a theoretical study and the suggested solutions have not been tested in an actual wireless network. Instead they have been tested by computer simulation to give an indication of improvements. Basic configurations are set to the same as in the IEEE 802.11 standard. </p><p>Different methods to reach possible improvements of a WLAN are studied, analyzed and simulated. Such methods are: priority, congestion management and multi-channel protocol. Simulations results show how the priority affects the wireless network and how a multi-channel protocol improves the latency and efficiency of the network. The simulation part is concentrated to show improvements of real-time traffic, which is time sensitive. With a multi- channel protocol the network can allow more users, i.e. more traffic. Also, the network will gain improvement in stability.</p>

<p>Vi har genomfört en undersökning på miljökontoret i Linköping som ansåg sig ha vissa problem med ECOS, ett databassystem som används för ärendehantering. </p><p>Syftet med vår undersökning är att presentera en teori kring användandet av ECOS på miljökontoret i Linköping samtidigt kommer vi att genomföra denna undersökning med grundad teori så som Glaser beskriver den. </p><p>Vi har valt att arbeta med grundad teori (GT) enligt Barney Glaser. Vi bestämde oss för att ha följande öppna frågeställning när vi inledde vår undersökning: </p><p>Hur använder sig de anställda på miljökontoret i Linköping av ECOS? </p><p>Det datamaterial som vi har analyserat har bestått av anteckningar över det som vi ansett vara väsentligt i intervjuer, observationer och dokument. Slutresultatet i en undersökning genomförd med GT blir en teori. En sådan teori beskriver inte data, den är grundad i data. </p><p>Beskrivningen av problemområdet och resultatet som kommit ur de data vi insamlat ligger till grund för den teori som vi anser kan fungera på området.</p>

<p>With the development of the Internet, illegal copying of electronic documents has become a growing problem. There is an increasing need of prevention in the field of pirate copying. One method is to mark the document by changing some of the words to synonyms. In this way it is possible to construct legal copies which do not differ in content but still are unique. Since the copies of the documents are unique, it is possible to trace the owner of a document and accordingly call him or her to account for pirate copying if several exactly similar copies are reaching the market. </p><p>The aim of this study was to investigate the possibility of exchanging words for synonyms in a text from a work of fiction, examining both the literary qualities of the manipulated texts and the security aspect. The conclusion of the study is that it is possible to mark texts of imaginative literature by means of the use of synonyms.</p>

<p>This Master’s Thesis within the area computer security concerns ”Computer viruses: The threat today and the expected future”. </p><p>Firstly, the definitions of computer virus and the related threats are presented; Secondly, current situation of computer viruses are discussed, the working and spreading mechanisms of computer viruses are reviewed in details, simplistic attitude of computer world in computer virus defence is analyzed; Thirdly, today’s influencing factors for near future computer virus epidemics are explained, then it further predicts new possible types of computer viruses in the near future; Furthermore, currently available anti-virus technologies are analyzed concerning both advantages and disadvantages; Finally, new promising trends in computer virus defence are explored in details.</p>

<p>Detta arbete har sin utgångspunkt i Tekniska Verkens och Östkrafts integrerade operationella system. Dessa är utvecklade för att stödja beslutsprocesser för bl.a. fysisk och finansiell elhandel. Integreringen har gjorts genom annamandet av en IRM-baserad lösning, av verksamheterna benämnt "datavaruhus". </p><p>Avregleringen av elmarknaden medförde större krav på elleverantörerna med avseende på flexibilitet och funktionalitet när kunderna fick välja elbolag själva. Det som främst bidrar till komplexiteten gällande elhandel är de många olika sorters elavtal som kan tecknas och det ständigt varierande inköpspriset på nordiska kraftbörsen. </p><p>För fallstudiens företag gäller att deras datavaruhuslösning lider av osedvanligt dåliga prestanda. Syftet med uppsatsen är att utifrån en kvalitativ studie försöka identifiera primära faktorer för dessa prestandaproblem. Vidare vill vi belysa hur man bör integrera befintliga operationella system för att uppnå goda prestanda. </p><p>Arbetets slutsats är att prestandaproblemen kan härledas både till det arkitekturella och det strukturella planet såväl som till valet att egenutveckla den logik som bearbetar data genom att hämta, transformera och uppdatera datavaruhuset. Ytterligare en faktor utgörs av den höga detaljeringsgrad som kännetecknar data i datavaruhuset.</p>

<p>The aim of this report is to examine if existing Digital Rights Management systems are useful and satisfying to the consumer, copyright owner and distributor. If not, is it possible to design a useful and satisfying Digital Rights Management system? </p><p>During the past few years, copyright owners of music, movies and other media have seen how piracy has increased with the introduction of affordable broadband technology. Record and movie corporations have pushed for a solution to piracy and one of them is Digital Rights Management. They want their customers to pay for and then enjoy the digital media but at the same time protect the rights of the copyright owner. That is what Digital Rights Management is all about; protect the copyright owner while allowing the consumer to enjoy their digital media. Digital Rights Management can restrict the users rights to copy and transfer the contents to other devices as well as restrict the number of times a user is allowed to use the media. </p><p>The present DRM systems are focusing on preventing digital media from being freely distributed by limiting the ability to copy or move the media. This puts limitations on fair use such as making personal copies of music. Copyright owners and distributors want more consumers to discover DRM, but so far, the consumers have shown little interest. </p><p>This report is based on various resources on the Internet such as white papers on Digital Rights Management, our own experimentation and on Microsoft Media Rights Management SDK documentation. </p><p>We do not believe it is possible to design a DRM system that consumers, copyright owners and distributors are satisfied with. It is not possible to combine the demands of copyright owners and the consumers’ claims of fair use.</p>

<p>This thesis suggests a security evaluation framework for distributed information systems, responsible for generating a system modelling technique and an evaluation method. The framework is flexible and divides the problem space into smaller, more accomplishable subtasks with the means to focus on specific problems, aspects or system scopes. The information system is modelled by dividing it into increasingly smaller parts, evaluate the separate parts and then build up the system “bottom up” by combining the components. Evaluated components are stored as reusable instances in a component library. The evaluation method is focusing on technological components and is based on the Security Functional Requirements (SFR) of the Common Criteria. The method consists of the following steps: (1) define several security values with different aspects, to get variable evaluations (2) change and establish the set of SFR to fit the thesis, (3) interpret evaluated security functions, and possibly translate them to CIA or PDR, (4) map characteristics from system components to SFR and (5) combine evaluated components into an evaluated subsystem. An ontology is used to, in a versatile and dynamic way, structure the taxonomy and relations of the system components, the security functions, the security values and the risk handling. It is also a step towards defining a common terminology for IT security.</p>

<p>IEEE 802.11 [1]is the standard that has emerged as a prevailing technology for the wireless local area networks. It can be considered the wireless version of Ethernet, which supports best-effortservice. IEEE is developing a new standard called 802.11e to be able to provide quality of service (QoS) in WLANs. Two possible methods have been proposed in [3]in order to improve the performance of service differentiation in the MAC layer. They are called PCWA (Practical Contention Window Adjustment) and AIPM (Adaptive Initiative Polling Machine). In this thesis, I will analyse both methods and propose new ideas to improve their performance, simulating the ideas concerning PCWA. Simulations show better general performance, especially for highest priorities flows, although the behaviour of the lowest priority one is reduced.</p>

<p>Nowadays Wireless LAN is playing a more and more important role in network systems. After 1999, in which the IEEE organization published its Wireless Local Network standard 802.11[1], many people saw the advantages of the standard but also the lack of support for multimedia streaming. A lot of research work has been done on the proposed IEEE 802.11e standard draft during the past 4 years. It is supposed to be able to fully support Quality of Service. The final version will be published early in 2004. In my thesis, I propose two possible methods to improve the performance of service differentiation in the MAC layer. The first one is calledPCWA (Practical Contention Window Adjustment). It is a method with which the station finds a best size of its contention window when running the EDCF (Enhanced Distributed Coordination Function) access method. It helps to improve the total system throughput, the jitter and the delay of traffics with different priorities. The second method is called AIPM (Adaptive Initiative Polling Machine). It uses the polling mechanism for differential service, intelligently arranging the polling time to reduce the delay as much as possible, achieving large improvement in performance. This method significantly increases the total system throughput, while the delay and jitter of the traffics are very much small in comparison to EDCF.</p>

<p>Session Initiation Protocol (SIP) arises as a new standard of establishing and releasing connections for vast variety of multimedia applications. The protocol may be used for voice calls, video calls, video conferencing, gaming and many more.</p><p>The 3GPP (3^rd Generation Partnership Project) suggests SIP as the signalling solution for 3^rd generation telephony. Thereby, this purely IP-centric protocol appears as a promising alternative to older signalling systems such as H.323, SS7 or analog signals in PSTN. In contrast to them, SIP does not focus on communication with PSTN network. It is more similar to HTTP than to any of the mentioned protocols. </p><p>The main standardisation body behind Session Initiation Protocol is The Internet Engineering Task Force (IETF). The most recent paper published on SIP is RFC 3261 [5]. Moreover, there are working groups within IETF that publish suggestions and extensions to the main standard. One of those extensions is “Caller Preferences for the Session Initiation Protocol (SIP)” [1]. </p><p>This document describes a set of new rules that allow a caller to express preferences about request handling in servers. They give ability to select which Uniform Resource Identifiers (URI) a request gets routed to, and to specify certain request handling directives in proxies and redirect servers. It does so by defining three new request header fields, Accept-Contact, Reject-Contact, and Request-Disposition, which specify the caller preferences. [1]. </p><p>The aim of this project is to extend the existing software with caller preferences and evaluate the new functionality.</p>