Novel chip antennas having an attractive EMC¡]Electromagnetic Compatibility¡^property for WLAN¡]Wireless Local Area Network¡^operations are demonstrated in this thesis. With the EMC property, the proposed antennas are suitable to be applied as internal antennas in mobile communication devices, such as the smart phones or PDA¡]Personal Digital Assistant¡^phones. With the antenna ground portion functioning as a new ground structure, the EM fringing fields in the surrounding region of the proposed antennas are greatly reduced to be negligible. When the possible RF shielding metal case or other electronic components are placed close to the proposed antennas, the antenna performances are almost unaffected. In other words, the isolation distance between the antenna and the nearby components will be no long required. This can lead to a compact integration of the proposed antennas with the nearby components in mobile communication devices. Details of the measured and simulated results of the proposed EMC chip antennas are presented and discussed.

Since wireless network technology has advanced swiftly and dropped in price, it became a widely used networking option among numerous organizations and even single home users. In spite of their widespread usage by private sector, wireless networks are still undesired alternative for the governments due to security concerns. Although wireless networks possessed lots of proven and documented security flaws at first, with the latest researches and developments this condition ameliorated by the time and wireless networks became much more robust to various security attacks. In this thesis, a secure wireless network architecture that will allow exchange of unclassified information, using 802.11 (Wi-fi) and 802.16 (WIMAX), will be proposed that could be established by governments in case of emergency situations, namely natural disasters or wars, where cable infrastructure becomes unavailable.

<p>There are several standards for wireless communication. People that are involved in computers and networking recognize names like Bluetooth, HiperLAN and IEEE 802.11. A fundamental part of an IEEE 802.11 node is the Medium Access Controller. It establishes and controls communication with other nodes, using a physical layer unit. This is the work that was carried out as a master thesis project at Ericsson Microelectronics. The main goal was to design, implement and evaluate a hardware interface between the MAC and the physical layer. An important part of the work was to find a suitable partition scheme for hardware and software and to achieve this, an investigation of processor-cycles usage was carried out to support design decisions. The hardware/software partition resulted in hardware-functionality for decode of received frames and automatic transmission of acknowledge frames.</p>

<p>Användningen av trådlöst nätverk blev under början av 2000-talet mycket populärt bland privatpersoner, genom dess mobila fördelar, Tekniken medförde många fördelar, men också många nackdelar och frågan var hur många som verkligen hade blivit uppmärksammade på eller kände till dessa och därefter valt att skydda sina trådlösa nätverk.</p><p>Det främsta syftet med denna uppsats var därmed att undersöka på vilken nivå säkerhetsmedvetandet låg i samhället vid användning av trådlöst nätverk vid gällande tidpunkt. Vidare handlade det också om att reda ut gällande rättsläge , vid handlingar mot eller via ett trådlöst nätverk, och mäta hur utbredd säkerhetsanvändningen var bland trådlösa hemmanätverk. För att besvara detta utgick vi från ett positivistiskt och deduktivt synsätt, med kvalitativa intervjuer för att reda ut gällande rättsläge, pejling av trådlöst nätverk för att mäta säkerhetsläget och kvantitativa enkätintervjuer, för att få fram typer av säkerhetsmedvetande, bland användare av trådlöst hemmanätverk. Innehållet i alla intervjuer baserades på fastställd fakta kring trådlöst nätverk, risker med tekniken, riskförebyggande säkerhetsrutiner och Svensk lag.</p><p>Vi konstaterade slutligen att gällande rättsläge för närvarande var föråldrat och inte anpassat att hantera de risker som trådlöst nätverk hade medfört. Vidare visade resultatet på ökad säkerhetsanvändning bland trådlösa nätverk i samhället, och att det överlag var yngre användare som stod för denna ökning. Yngre användare visade sig även överlag ha ett högre säkerhetsmedvetande, än äldre, och då särskilt hög teknisk kunskap</p> / <p>The usage of Wireless local area networks (WLAN) became very popular amongst private citizens, during the beginning of the 21 century, because of its mobile advantages. The technology brought many advantages, but also many disadvantages and the question was how many had noticed or knew that these existed and afterwards had chosen to secure their WLAN.</p><p>The main purpose of this thesis was to examine the current level of security awareness, in the community, when using WLAN. Other goals were to investigate the current general legal context, about actions against or through a WLAN, and measure the widespread usage of security within WLAN. To answer this we used a positivistic and deductive approach, with qualitative interviews to sort out the current general legal context, Wardriving to find and measure the current state of security within WLAN's and quantitative questionnaires to find out the most common types of security awareness amongst users of WLAN. The content of all this was based on facts about the WLAN technology, the risks that comes with it, risk preventing security routines and the Swedish law.</p><p>Finally we established that the current general legal context was out-of-date and not adapted to handle the new risks that WLAN had brought. Further on the result also showed a increased usage of security amongst WLAN in the community and that the main reason for this was the younger WLAN owners. Younger users also turned out to have higher security awareness, than older users, and particularly very high technical knowledge.</p>

Während sich der Chemnitzer Linux-Tag über die vergangenen fünf Jahre mit jedem Mal in der Zahl der Aussteller, Helfer und Gäste steigerte, wuchs auch in jedem Jahr das Tagungsnetzwerk. Den Informatikern wird häufig nachgesagt, daß sie wenig dokumentieren würden. Dieses Vorurteil traf auch für das Netzwerk der vergangenen Chemnitzer Linux-Tage zu. Unter anderem, um diesem Mißstand abzuhelfen, haben wir uns bemüht, möglichst detailliert Informationen über Konzept, eingesetzte Technologieen und konkrete Konfiguration des Tagungsnetzwerks des Chemnitzer Linux-Tags 2004 zusammenzutragen.

Das Chemnitzer StudentenNetz (CSN) verwaltet ein mittelgroßes Netzwerk in den Wohnheimen des Studentenwerkes Chemnitz-Zwickau. Mitarbeitern und Interessenten erhalten einen Überblick und Einblick in die vorhandene Netzstruktur und die Konfiguration der verwendeten Technik. Es wird auch auf mögliche Szenarien für zukünftige Entwicklungen eingegangen.

Civic issues in a society can be reported through a crowdsourcing web application. People can download the application on their smartphones and report the issues such as a pothole or broken streetlight. The report is submitted by taking a photo of the issue and additional information is entered. At first, the reports are submitted to a call center and after analyzing they will be transferred to organizations responsible for this type of events. In such a crowdsourcing project it is very vital to motivate people to participate in the project. The reports are supplied by users and without an acceptable number of users the application would be useless. In addition, having the exact location of a report is very helpful to facilitate the process of solving civic issues. Positioning with smartphones is not very accurate as they do not have strong and accurate GPSs. Therefore, there is a need to improve the accuracy of the positioning process and consequently accuracy of the spatial data. The aim of this thesis is to investigate how to employ GIS to help reporting civic issues and how to design an interesting client interface for such an application, in order to motivate user to download and use it. The goal is also to find out shortcomings and weaknesses of the positioning with smartphones and find a way to improve its accuracy.Some of successful similar applications’ structures and their interfaces were reviewed. In addition, a survey among existing users of crowdsourcing applications has been done in order to find out how to design the application to be interesting for users. Furthermore, some techniques and methods were chosen in order to improve the GPS accuracy especially in the places with a low GPS signal strength. These methods exploit WLAN and some of embedded features in a smartphone such as microphone, camera, accelerometer, gyroscope to improve the positioning accuracy. In the end, along reporting civic issues the user is able to report and get information about cheap and appropriate necessities and public events in different geographical areas through a map-based application. Furthermore, he or she is benefited by some location-based services such as online-food or taxi. The client application’s interface was designed for iPhone.This GIS-based mobile application would be an appropriate alternative for the old reporting methods like phone call or mail. Nevertheless, reporting civic issues itself, cannot be necessarily a strong motivation to attract the user to download and use the application. Therefore, desired feedbacks of the crowd need to be found out in order to encourage them to spend their time for the application. User needs to get motivated to use the application and considered additional parts can be very helpful to reach this aim.

Nowadays the popularity of WLANs is growing very rapidly. The basic solution for the connection of WLAN users to the global internet network is using leased lines or the other standard data transmission networks. But there may occur situations, when the only network for the data transmission we can use for the connection to the internet, is GSM network. In such a case, we are proposing to connect the users of WAN/WLAN networks by using GSM network, which has complete coverage in the territory of Lithuania. To guarantee the sufficient data transfer rate, we use bonding of several parallel GPRS/EDGE/UMTS channels into one total channel. In such a way we increase the reliability and data transfer rate of the total mobile data transmission channel. The parallel channels are bonded into one total channel by using either the hardware (Cisco) routers, or the software routers, configured using network administration tools of Linux operating system. In this work we give all the tools and configuration settings necessary for the realization of such a system. The results of QoS characteristics measurements are given too. We measure packet delay and data transfer rate. The majority of measurements are made by using several parallel GPRS channels because of wide spread GPRS technologies. The key accent of the system is free selection of the physical layer (OSI model) of the parallel channel. So we can bond either several GPRS, or EDGE, or UMTS channels.

With the advance of wireless access technologies, the IEEE 802.11 wireless local area network (WLAN) has gained significant increase in popularity and deployment due to the substantially improved transmission rate and decreased deployment costs. However, this same widespread deployment makes WLANs an attractive target for network attacks. Several vulnerabilities have been identified and reported regarding the security of the current 802.11 standards. To address those security weaknesses, IEEE standard committees proposed the 802.11i amendment to enhance WLAN security. The 802.11i standard has demonstrated the capability of providing satisfactory mutual authentication, better data confidentiality, and key management support, however, the design of 802.11i does not consider network availability. Therefore, it has been suggested that 802.11i is highly susceptible to malicious denial-of-service (DoS) attacks, which exploit the vulnerability of unprotected management frames. This research first investigates common DoS vulnerabilities in a Robust Security Network (RSN), which is defined in the 802.11i standard, and presents an empirical analysis of such attacks – in particular, flooding-based DoS attacks. To address those DoS issues, this thesis proposes a novel design and implementation of a lightweight stateless authentication scheme that enables wireless access points (APs) to establish a trust relationship with an associating client and derive validating keys that can be used to mutually authenticate subsequent layer-2 (link layer) management frames. The quality of service provisioning for real-time services over a WLAN requires the total latency of handoff between APs to be small in order to achieve seamless roaming. Thus, this thesis further extends the proposed link-layer authentication into a secure fast handoff solution that addresses DoS vulnerabilities as well as improving the existing 802.11i handoff performance. A location management scheme is also proposed to minimise the number of channels required to scan by the roaming client in order to reduce the scanning delay, which could normally take up 90% of the total handoff latency. In order to acquire practical data to evaluate the proposed schemes, a prototype network has been implemented as an experimental testbed using open source tools and drivers. This testbed allows practical data to be collected and analysed. The result successfully demonstrated that not only the proposed authentication scheme eradicates most of the DoS vulnerabilities, but also substantially improved the handoff performance to a level suitable for supporting real-time services.

Τα σύγχρονα ασύρματα δίκτυα, διαρκώς εξελισσόμενα, δύναται να παρέχουν πλήθος σύγχρονων υπηρεσιών, ακόμα κι εκείνων που είναι ιδιαίτερα απαιτητικά σε πόρους. Αρχικά, στην εργασία αυτή, παρουσιάζονται τα χαρακτηριστικά, η δομή και η λειτουργία δύο ευρέως διαδεδομένων δικτύων:WLAN και UMTS, ενώ μελετάται η απόδοση τους σε διάφορες υπηρεσίες υπό αυξανόμενο αριθμό χρηστών. Κατόπιν, γίνεται μελέτη και προσομοίωση αυτών για διάφορα σενάρια και προκύπτουν αποτελέσματα για τη βέλτιστη αξιοποίηση των πόρων που παρέχει το κάθε δίκτυο στο χρήστη. Ακολούθως, υλοποιείται η διασύνδεση των δύο δικτύων προς σχηματισμό ενός διασυνεργαζόμενου δικτύου, με σκοπό την εκμετάλλευση των πλεονεκτημάτων που παρέχει κάθε δίκτυο ξεχωριστά. / Modern wireless networks, constantly evolving, can provide a range of modern services, even those that are highly demanding in resources. Initially, in this paper,we present the characteristics, structure and operation of two widespread networks: WLAN and UMTS, and study their performance in various departments under increasing number of users. Then, there is a simulation of these scenarios and resulting effects on the optimal use of resources provided by each network user. Subsequently we implement the interconnection of two networks to form one inter-network, in order to exploit the advantages offered by each network separately.