Cheung Cheuk Lun. / Thesis submitted in: July 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 109). / Abstracts in English and Chinese. / Abstract --- p.1 / Chapter 1 --- Introduction --- p.3 / Chapter 1.1 --- Differentiation from existing products --- p.6 / Chapter 1.2 --- Problems --- p.6 / Chapter 1.3 --- Assumption --- p.9 / Chapter 2 --- Study of bulk transfer --- p.10 / Chapter 2.1 --- Simple wireless solution --- p.10 / Chapter 2.2 --- Problems of the simple wireless solution --- p.10 / Chapter 2.2.1 --- Low performance due to header overhead --- p.12 / Chapter 2.2.2 --- Low performance due to unnecessary packets --- p.12 / Chapter 2.2.3 --- Model derivation --- p.12 / Chapter 2.2.4 --- Performance study --- p.17 / Chapter 2.3 --- Packed wireless solution --- p.19 / Chapter 2.3.1 --- Example --- p.19 / Chapter 2.3.2 --- Solved problems --- p.21 / Chapter 2.3.3 --- Model derivation --- p.22 / Chapter 2.3.4 --- Performance study --- p.24 / Chapter 2.3.4 --- Performance study on the effect of the value of n --- p.25 / Chapter 2.4 --- Controllable packed wireless solution --- p.27 / Chapter 2.4.1 --- Problem --- p.27 / Chapter 2.4.2 --- Analysis --- p.27 / Chapter 2.4.3 --- Solution --- p.29 / Chapter 2.4.4 --- Model derivation --- p.33 / Chapter 2.4.5 --- Performance study --- p.35 / Chapter 2.4.6 --- Performance study on the effect of the sliding window size --- p.36 / Chapter 2.5 --- Summary of performance study --- p.41 / Chapter 2.5.1 --- Comparison of the throughput between four cases --- p.41 / Chapter 2.5.2 --- Study of how the throughput-varies with the processing time --- p.44 / Chapter 2.6 --- Simulation --- p.47 / Chapter 2.6.1 --- Measuring the packet loss rate and the throughput --- p.49 / Chapter 2.6.2 --- Studying the throughput against the distance --- p.50 / Chapter 2.6.3 --- Studying the throughput against the packet loss rate --- p.53 / Chapter 2.7 --- Conclusion --- p.54 / Chapter 3 --- Study of interrupt transfer --- p.55 / Chapter 3.1 --- Problem --- p.55 / Chapter 3.2 --- Solution --- p.56 / Chapter 3.2.1 --- Remote polling --- p.56 / Chapter 3.3 --- Feasibility of the solution --- p.58 / Chapter 3.4 --- The problem of Distributed Coordination Function collision --- p.60 / Chapter 3.5 --- Collision avoidance --- p.60 / Chapter 3.6 --- Model derivation --- p.61 / Chapter 3.6.1 --- Wired case --- p.61 / Chapter 3.6.2 --- Wireless solution (remote polling) --- p.62 / Chapter 3.7 --- Maximum allowed request generation frequency --- p.64 / Chapter 3.7.1 --- More than one interrupt transfer --- p.64 / Chapter 3.7.2 --- More than one bulk transfer --- p.64 / Chapter 3.7.3 --- Maximum allowed request generation frequency --- p.65 / Chapter 3.8 --- Conclusion --- p.65 / Chapter 4 --- System architecture issues --- p.66 / Chapter 4.1 --- USB network --- p.66 / Chapter 4.1.1 --- Problems --- p.66 / Chapter 4.1.2 --- Solution --- p.66 / Chapter 4.1.3 --- Conclusion --- p.69 / Chapter 4.2 --- Security --- p.70 / Chapter 4.2.1 --- Suggested solution --- p.70 / Chapter 4.2.2 --- Conclusion --- p.72 / Chapter 4.3 --- Cost --- p.72 / Chapter 4.4 --- Power supply --- p.73 / Chapter 5 --- Conclusion --- p.75 / Appendix --- p.77 / Chapter A. --- Wireless USB (WUSB) --- p.77 / Chapter B. --- Introduction of USB --- p.83 / Chapter C. --- Framing details of 802.11 --- p.99 / Chapter D. --- A case study of a USB device --- p.102 / Chapter E. --- Reference of notations used in figures --- p.106 / Chapter F. --- Values of all symbols --- p.107 / Reference i --- p.109

Jiang Libin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 84-87). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations and Contributions --- p.1 / Chapter 1.2 --- Related Works --- p.3 / Chapter 1.3 --- Organization of the Thesis --- p.4 / Chapter Chapter 2 --- Background --- p.6 / Chapter 2.1 --- IEEE 802.11 --- p.6 / Chapter 2.1.1 --- Basics of 802.11 Standard --- p.6 / Chapter 2.1.2 --- Types of Networks --- p.10 / Chapter 2.1.3 --- Automatic Repeat request (ARQ) in 802.11b --- p.11 / Chapter 2.2 --- Hidden- and Exposed-node Problems --- p.15 / Chapter Chapter 3 --- Physical Interference Constraints and Protocol Constraints --- p.19 / Chapter 3.1 --- Protocol-independent Physical Interference Constraints --- p.19 / Chapter 3.2 --- Protocol-specific Physical Interference Constraints --- p.21 / Chapter 3.3 --- Protocol Collision-Prevention Constraints in 802.11 --- p.22 / Chapter 3.3.1 --- Transmitter-Side Carrier-Sensing Constraints --- p.22 / Chapter 3.3.2 --- Receiver-Side Carrier Sensing Constraints --- p.24 / Chapter Chapter 4 --- Formal Definitions of EN and HN Using a Graph Model --- p.27 / Chapter Chapter 5 --- Selective Disregard of NAVs (SDN) --- p.36 / Chapter 5.1 --- SDN. I - Turning off Physical Carrier Sensing and Using Receiver Restart Mode --- p.38 / Chapter 5.2 --- SDN.II - Selective Disregard of NAV (SDN) --- p.38 / Chapter 5.3 --- SDN.III - Constructing s-graph using Power Exchange Algorithm (PE) --- p.40 / Chapter Chapter 6 --- EN and Its Impact on Scalability --- p.42 / Chapter 6.1 --- Validation of SDN by NS-2 Simulations --- p.43 / Chapter 6.2 --- Scalability of SDN --- p.46 / Chapter 6.3 --- Non-Scalability of 802.11 --- p.47 / Chapter Chapter 7 --- Hidden-node Free Design (HFD) --- p.51 / Chapter 7.1 --- HFD for IEEE 802.11 Basic Access Mode --- p.52 / Chapter 7.1.1 --- HFD for basic access mode --- p.52 / Chapter 7.1.2 --- Proof of the HN-free property --- p.56 / Chapter 7.2 --- HFD for IEEE 802.11 RTS/CTS Access Mode --- p.59 / Chapter Chapter 8 --- Performance Evaluation of HFD --- p.62 / Chapter 8.1 --- HFD for Basic Access Mode --- p.62 / Chapter 8.2 --- HFD for RTS/CTS Access Mode --- p.64 / Chapter Chapter 9 --- Combination of SDN and HFD --- p.68 / Chapter Chapter 10 --- Conclusion --- p.75 / Appendices --- p.78 / References --- p.84

Ng Ping-chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 71-72). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview and Motivation --- p.1 / Chapter 1.2 --- Background of Offered Load Control --- p.2 / Chapter 1.3 --- Background of Stability Control --- p.3 / Chapter 1.4 --- Organization of the Thesis --- p.4 / Chapter Chapter 2 --- Performance Problems and Solutions --- p.6 / Chapter 2.1 --- Simulation Set-up --- p.6 / Chapter 2.2 --- High Packet-Drop Rate --- p.7 / Chapter 2.3 --- Re-routing Instability --- p.8 / Chapter 2.3.1 --- Hidden-Node Problem --- p.8 / Chapter 2.3.2 --- Ineffectiveness of Solving Hidden-Node Problem with RTS/CTS …… --- p.9 / Chapter 2.4 --- Solutions to High-Packet Loss Rate and Re-routing Instability --- p.10 / Chapter 2.4.1 --- Link-Failure Re-routing --- p.11 / Chapter 2.4.2 --- Controlling Offered Load --- p.13 / Chapter 2.5 --- Verification of Simulation Results with Real-life Experimental Measurements --- p.14 / Chapter Chapter 3 --- Offered Load Control --- p.16 / Chapter 3.1 --- Capacity Limited by the Hidden-node and Exposed-node Problems --- p.16 / Chapter 3.1.1 --- Signal Capture --- p.18 / Chapter 3.1.2 --- Analysis of Vulnerable Period induced by Hidden Nodes --- p.20 / Chapter 3.1.3 --- Analysis of Vulnerable Period induced by Exposed Nodes --- p.21 / Chapter 3.1.4 --- Sustainable Throughput --- p.22 / Chapter 3.2 --- Capacity Limited by Carrier Sensing Property --- p.23 / Chapter 3.3 --- Numerical Results --- p.26 / Chapter 3.4 --- General Throughput Analysis of a Single Multi-hop Traffic Flow --- p.29 / Chapter 3.5 --- Throughput Analysis on Topologies with Variable Distances between Successive Nodes --- p.31 / Chapter Chapter 4 --- Discussions of Other Special Cases --- p.33 / Chapter 4.1 --- A Carrier-sensing Limited Example --- p.33 / Chapter 4.2 --- A Practical Solution to Improve Throughput --- p.34 / Chapter Chapter 5 --- Achieving Fairness in Other Network Topologies --- p.36 / Chapter 5.1 --- Lattice Topology --- p.36 / Chapter Chapter 6 --- Stability Control --- p.39 / Chapter 6.1 --- Ad-hoc routing protocols --- p.39 / Chapter 6.2 --- Proposed scheme --- p.40 / Chapter 6.2.1 --- Original AODV --- p.41 / Chapter 6.2.2 --- AODV with Proposed Scheme --- p.42 / Chapter 6.2.2.1 --- A Single Flow in a Single Chain of Nodes --- p.43 / Chapter 6.2.2.2 --- Real-break Case --- p.44 / Chapter 6.3 --- Improvements --- p.45 / Chapter Chapter 7 --- Impacts of Data Transmission Rate and Payload Size --- p.48 / Chapter 7.1 --- Signal Capture --- p.48 / Chapter 7.2 --- Vulnerable region --- p.50 / Chapter Chapter 8 --- Performance Enhancements in Multiple Flows --- p.53 / Chapter 8.1 --- Impacts of Re-routing Instability in Two Flow Topology --- p.53 / Chapter 8.2 --- Impacts of Vulnerable Periods in Multiple Flow Topologies --- p.55 / Chapter 8.2.1 --- The Vulnerable Period induced by Individual Hidden-terminal Flow --- p.57 / Chapter 8.2.2 --- The Number of Hidden-terminal Flows --- p.58 / Chapter 8.2.3 --- Correlation between Hidden-terminal Flows --- p.60 / Chapter Chapter 9 --- Conclusion --- p.63 / Chapter Appendix A: --- General Throughput Analysis of a Single Multi-hop Traffic Flow --- p.67 / Chapter A.l --- Capacity Limited by Hidden-node and Exposed-Node --- p.67 / Chapter A.1.1 --- Sustainable Throughput --- p.68 / Chapter A.2 --- Capacity Limited by Carrier Sensing Property --- p.68 / Bibliography --- p.71

Nam Chung Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 68-71). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview and Motivation --- p.1 / Chapter 1.2 --- Organization of the Thesis --- p.5 / Chapter Chapter 2 --- Background --- p.6 / Chapter 2.1 --- Basics of 802.11 Standard --- p.6 / Chapter 2.1.1 --- Distributed Coordination Function (DCF) / Point Coordination Function (PCF) --- p.7 / Chapter 2.1.2 --- RTS/CTS --- p.8 / Chapter 2.2 --- Types of Networks --- p.9 / Chapter 2.3 --- Automatic Repeat request (ARQ) in 802.11b --- p.11 / Chapter 2.3.1 --- Importance of Link-layer ARQ in Wireless Networks --- p.12 / Chapter 2.3.2 --- MAC Algorithm of 802.11b Standard --- p.13 / Chapter 2.3.3 --- Modified MAC algorithm in 802.11b commercial products --- p.14 / Chapter 2.4 --- Automatic Adjustment of Radio Data Rate in Commercial 802.11b Products --- p.15 / Chapter Chapter 3 --- Head-of-Line Blocking in Access Points --- p.17 / Chapter 3.1 --- Cause of HOL blocking in 802.11b --- p.17 / Chapter 3.1.1 --- Calculation of Worst-Case Service Time for Packet at Head of Queue --- p.19 / Chapter 3.2 --- Simulation Settings --- p.21 / Chapter 3.2.1 --- Propagation Models Available in NS2 --- p.21 / Chapter 3.2.2 --- Variables of Shadowing Model --- p.25 / Chapter 3.3 --- Simulation Results on UDP --- p.26 / Chapter 3.4 --- Experimental Results on UDP --- p.28 / Chapter 3.5 --- Simulation Results on TCP --- p.32 / Chapter 3.6 --- Experimental Results on TCP --- p.34 / Chapter 3.7 --- Possible Solutions of HOL Blocking Problem --- p.35 / Chapter 3.7.1 --- Weakening Link-layer ARQ in 802.11b --- p.36 / Chapter 3.7.2 --- Effectiveness of ARQ in 802.11b --- p.37 / Chapter 3.7.2.1 --- Set-up for Network Experiments --- p.38 / Chapter 3.7.2.2 --- Results and Analysis --- p.39 / Chapter 3.7.3 --- Virtual Queuing --- p.45 / Chapter Chapter 4 --- Study of Uplink Traffic --- p.50 / Chapter 4.1 --- Poor Pulling Down the Rich --- p.51 / Chapter 4.2 --- Signal Capturing Effect --- p.53 / Chapter 4.2.1 --- Mathematical Analysis of Signal Capturing Effect --- p.55 / Chapter Chapter 5 --- Packet Loss Patterns in 802.11b WLAN --- p.61 / Chapter 5.1 --- """Random Loss"" vs ""Bursty Loss""" --- p.61 / Chapter 5.2 --- Experimental Evaluation --- p.62 / Chapter Chapter 6 --- Conclusion --- p.65 / Bibliography --- p.68

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Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2008

Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto, INESC Porto. 2009

Avec le déploiement de la technologie WiFi ces dernières années, les réseaux locaux sans fil connaissent un grand succès auprès des institutions et les réseaux ad hoc suscitent un réel intérêt auprès de la communauté de R&D. Parallèlement, avec l'émergence des services multimédias dans les réseaux mobiles, des travaux pour l'introduction de la qualité de service dans les réseaux ad hoc ont été proposés. Les études existantes sont souvent basées sur des hypothèses limitées et inadaptées aux propriétés des réseaux ad hoc. Dans cette thèse, nous proposons d'abord un protocole de routage avec différenciation de terminaux qui maximise les liens sans fil de haute qualité. Le but d'une telle approche est de prendre en compte l'hétérogénéité des nœuds dans les réseaux ad hoc et de supporter les situations où des terminaux mobiles peuvent accepter ou refuser la fonction de routage. Notre proposition apporte une solution aux variations des capacités des liens sans fil en routant les paquets de préférence à travers les routeurs collaboratifs ayant une grande capacité de transmission dans le but de maintenir une meilleure qualité de lien (grand débit) des routes dans le réseau. Nous prouvons ensuite la nécessité d'une gestion multicouches de la qualité de service dans un tel environnement. Cela permet de définir une stratégie de QoS en plusieurs couches de communication dans le but de prendre en considération les contraintes liées aux spécificités des réseaux mobiles ad hoc. Une combinaison des mécanismes de qualité de service au niveau IP et MAC (IEEE 802.11) est étudiée. De plus le principe de routage avec différenciation de terminaux décrit ci-dessus a été combiné avec la gestion de la qualité de service IP et MAC. Un autre volet de la thèse traite l'aspect de contrôle de topologie dans les réseaux ad hoc. Il consiste à contrôler la morphologie du réseau en utilisant la mobilité d'un ensemble de routeurs dédiés. Le principe est d'utiliser positivement la mobilité, qui est habituellement subie dans le réseau, afin d'améliorer les performances de ce dernier. Ainsi, des stratégies de déploiement des routeurs dédiés sont étudiées (dans un réseau ad hoc autonome ou interconnecté à une infrastructure) dans le but d'offrir une meilleure connectivité ou pour assurer un meilleur support de la qualité de service des applications temps réel. Pour les deux stratégies, le problème a été formulé comme un problème de programmation linéaire entière mixte. Cette thèse a été réalisée dans le cadre du projet ITEA Ambience. Dans ce contexte, nous avons entre autres contribué à la réalisation d'une plate-forme, qui illustre un exemple d'applications des réseaux ad hoc où des mécanismes décrits dans les parties précédentes sont utilisés afin d'améliorer les performances du système et répondre aux besoins des utilisateurs mobiles, dans un contexte hétérogène sécurisé. Mots-clés : Qualité de service, IEEE 802.11, Différenciation de services, Hétérogénéité des nœuds, Routage ad hoc, Contrôle de topologie, Routeurs dédiés, Connectivité.

<p>Wireless communication is being developed in the last years day by day, there are several standards that talks about it. We are going to go through the IEEE standard 802.11 which talks about wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Looking this more carefully we will study MAC specifications and its environment. </p><p>The work that ISY department at Institute of Technology of Linkoping University has proposed is to design a MAC sublayer implementation for WLANs using C language programming and testing it with the test environment called “test bench”. This test bench will simulate LLC sublayer and PHY layer, in this way, our MAC implementation will has to interact with it. Therefore we will simulate a wireless network where we are going to have a short number of stations and we are going to look at carefully the MAC sublayer response in an ad hoc network.</p>

The IEEE 802.11a has become the mainstream protocol used in modern wireless communication system due to its high propagation rate of data (54 Mb/s). To meet high propagation rates, the communication devices used in IEEE 802.11a protocol usually present a high conversion gain and a high linearity (denoted as third order intercept point, IIP3). The IIP3 of conventional up- and down-conversion mixers are only about 0 dBm and -5 dBm, which fail to achieve a high propagation rate of data. This thesis utilizes the TSMC 0.18 &#x00B5;m CMOS technology to design and fabrication up- and down-conversion mixers with very high linearity for IEEE 802.11a application. The proposed high-linearity up-conversion mixer with 1.01 mm ¡Ñ 0.85 mm chip size and its wide bandwidth (5~6 GHz) is well suited for IEEE 802.11a application. To enhance the linearity and bandwidth, a transconductor stage with gm-boosted structure, a switch stgae with LO-body grounded structure and a load stage with shunt peaking structure are adopted in this research. Under 5.2/5.4/5.8 GHz operating frequencies, the implemented up-conversion mixer demonstrates a high conversion gain of 6.8/7.1/6.3 dB and a high linearity of 8.9/9/13.2 dBm, respectivly. In addition, a moderate consuming power (6.86 mW) of such mixer can be achieved at 1.2 V supply voltage. On the other hand, this thesis also designed and fabricated a high-linearity down-conversion mixer with chip size of 1.02 mm ¡Ñ 0.86 mm and 5.2 GHz center frequency. To improve the linearity and isolation and reduce the high-order noise, a transconductor stage with dual-gate structure and a load stage with RC-tank structure are adopted in this research. According to the EM-simulation resutls, the proposed down-conversion mixer presents a moderate conversion gain of 6 dB and a high linearity of 0.8 dBm. Additionly, a moderate consuming power (6.75 mW) of such mixer can be achieved at 1.8 V supply voltage.