ABSTRACT In the past decade there has been a steady growth in development and implementation of wireless Local Area Networks and emerged as in the largest sectors of the telecommunication industry. Wireless local area network (WLANs) provides connectivity, mobility, and much higher performance and achievable data rate. WLAN is a new medium of access technology in the Local Area Network (LAN) world. Mostly WLAN applications are used in public sectors such as airports, banks, hotels, offices, city centres because of the flexibility of the people. Orthongonal Frequency Division Multiplexing OFDM has been adopted by IEEE 802.11’s standard as a transmission technique for high data rate in WLANs. Now IEEE 802.11 standard has been expanded to a family of WLAN standards. 802.11a and 802.11g both are used Orthongonal Frequency Division Multiplexing (OFDM) but operate in different frequency bands. It is shown that 802.11a provides high speed throughout the entire coverage area and long term solution however it does not provide better solution in most cases as compared to IEEE 802.11g. Matlab Simulation model based on IEEE 802.11a/g using different modulation and demodulation techniques such as BPSK, QPSK and QAM to analysis the best performance of IEEE 802.11a/g with implementation of OFDM. Keywords: Orthongonal Frequency Division Multiplexing (OFDM), IEEE 802.11s family, Wireless Local Area Network, Simulation, MATLAB / Summary The objective of this research is to examine the performance of the IEEE 802.11a and IEEE 802.11g WLAN comparing through OFDM modulation techniques. It is found that IEEE 802.11a/g provides similar quality except IEEE 802.11g provides wider range but range is the controversial topic in WLAN medium. In the other hand IEEE 802.11a provides more channels in 5 GHz bands as well as have a good enough signal qualities but there is range limitation factor. Range limitation in the enterprise and public sectors can be adjusting through installations more APs. The main disadvantage of the 802.11g is the frequency band is common and interference from the other networking technology such as Bluetooth, 2.04 GHz cordless phone and IEEE 802.11a avoid this interference because its operate in 5.GHz bands. Consequently, all the simulation is a comparison between simulated BER for a computer system and theoretical BER for serial systems it has been proved through simulation results that theoretical BER and simulated BER under AWGN are good agreement with each other. It means that I and Q points on constellation are much closer to each other the data error can be reduced as well as transmission easily influenced to noise. 64 QAM modulations are much better than 16 QAM when BER decrease SNR will be increase because signal is stronger than noise. 64 QAM modulations need higher bandwidth and give an excellent data rates as compared to 16 QAM.

Le domaine de la recherche dans les multi-standards, les systèmes multi-bandes, architectures, et circuits a été un thème populaire. La perspective est d'avoir des dispositifs qui peuvent être adaptés, parfaitement, aux différents réseaux tout en offrant d'excellentes fonctionnalités sur les différents technologies d’accès radio. Les architectures de transmetteurs configurables ciblant les cas d'utilisation complémentaires des WiFi-WiGig ont été étudiés. Des approches novatrices basées sur des DAC FIR semi-numériques configurables à grande vitesse sont proposées. Les DAC de FIR nécessitent des filtres longs avec des coefficients de résolution élevés pour atteindre des niveaux d'atténuation de stopband satisfaisants aux exigences de bruit hors bande. Normalement, cela limite la vitesse et se traduit par une grande surface de silicium. Dans ce travail, les techniques de conception de circuits sont développées de sorte qu'un élément de circuit unitaire réalisant un coefficient d'une fonction de transfert peut être réutilisé dans la réalisation d’un coefficient d'une autre fonction de transfert. Une puce prototype de passe-haut FIR DAC qui peut être configuré pour le fonctionnement de l'IEEE 802.11ac et les standards IEEE 802.11ad a été mise en œuvre sur une technologie CMOS 28nm FDSOI de STMicroelectronics. Le test De cette puce a démontré la validité des architectures d'émetteur proposées. Le puce prototype peut traiter des signaux des bandes de base aussi larges que 63,63 MHz et 300 MHz à une fréquence d'horloge de 1,4 GHz avec une consommation de 103,07 mW dans le 802.11ac et 86,89 mW dans le mode 802.11ad. / The vision of research into multi-standard and multi-band systems, architectures, and circuits has been to develop devices which can hope seamlessly from one network to the other while delivering excellent functionality in different radio access technologies.In this work, configurable transmitter architectures based on FIR DACs which target WiFi-WiGig complementary use cases have been studied. FIR DACs require long filters with high resolution coefficients to meet high out-of-band noise attenuation. Normally, this limits speed and results in large area. In this work, circuit techniques are developed so that a unit circuit element realizing a coefficient of one transfer function can be re-used in realizing a different-valued coefficient of another transfer function. The work also proposes topologies that exploit digital signal processing at advanced nodes to implement quadrature modulation while realizing up-conversion, digital-to-analog conversion and image and quantization filtering in one configurable FIR DAC block. A prototype high pass FIR DAC chip which can be configured for processing IEEE 802.11ac and IEEE 802.11ad signals was implemented in ST CMOS 28nm FDSOI technology. The test of this chip has demonstrated the validity of the proposed transmitter architectures. The prototype chip can process baseband signals as wide as 63.63 MHz and 300 MHz at a clock frequency of 1.4 GHz while consuming 103.07 mW in the 802.11ac and 86.89 mW in the 802.11ad modes.

隨著IEEE 802.11無線傳輸頻率的快速發展，而傳輸距離卻隨著縮短，使得我們考慮多跳接的傳輸方式來擴展通訊的範圍。但是在IEEE 802.11 的多跳接無線網路中並沒有服務品質的保證，而且在傳輸上的效能不高，因此我們希望在IEEE 802.11 多跳接的無線網路中改善傳輸效能且提供服務品質保證。在這篇論文中，我們提出了一個安排MAC存取的方法，來達到服務品質保證。我們使用一個樹狀架構來建構這個無線網路並且運作訊標繞樹的動作來建立我們的分離集合，而分離集合提供我們安排無衝突傳輸。當訊務流在這個網路中產生，我們的方法能夠有效的安排MAC存取並且保證不同類型訊務之品質。我們同時也提供一種適應性安排機制，來有效利用整個網路的效能，並且避免重新安排整個網路的MAC存取規畫，來維持網路品質在適當的滿意度。實驗結果顯示我們在多跳接的無線網路中有效的達到服務品質保證。 / With fast development of radio frequency, the wireless communication in IEEE 802.11 is growing up to high transmission rate (802.11g). However the distance of transmission decreases when wave frequency increases. Thus there is growing need to extend communication distance through multihop transmissions. But there is no QoS in IEEE 802.11 Multihop Wireless Networks; it has poor performance on transmission. Thus we are motivated to provide QoS in IEEE 802.11 Multihop Wireless Networks. In This Thesis, we propose a MAC Access Scheduling Scheme to support guaranteed QoS in IEEE 802.11 Multihop Wireless Networks. We use a tree-based architecture to construct the network and form the operation of token traversal. Token traversal operation builds the Disjoint Set to support scheduling collision-free transmission. When traffic is generated to the network, our scheme provides efficient schedule of MAC access and guarantee the QoS of different types of traffic. We also provide a adaptive scheduling to utilize the network performance and avoid the overhead of re-schedule to maintain the network quality at a satisfied level. The simulation results show we achieve the network QoS efficiently and provide guaranteed QoS.

With the ever increasing popularity of wireless internet, its scale is broadening. While the IEEE 802.15 standard provides the parameters necessary for a wireless personal area network (WPAN), the IEEE 802.16a standard provides broadband wireless access (BWA), or a wireless metropolitan area network (WMAN). Popularly referred to as Wi Max, the standard uses cellular topography with a base station and subscriber station and cuts down on infrastructure and thus can be used in most environments. The 802.16a standard can take advantage of the popular OFDM modulation technique. This thesis takes a developed synchronization algorithm and tests its performance on 802.16a. In addition, it tests the standard's performance in different types of channel. Various techniques are evaluated including interleaving and antenna diversity. The 802.16a standard employs a form of transmit diversity called Space Time Coding. The transmit diversity is compared with Maximal Ratio Combining receiver diversity. The evaluation was done in simulation developed in Matlab; the simulations show drastic improvement when using the aforementioned techniques, particularly diversity.

This research analyzes the design and implementation of a Maritime Command, Control, Computer, and Communications for Intelligence, Surveillance, and Reconnaissance (C4ISR) fly away kit (FLAK) in order to combat asymmetric threats in the coalition maritime environment. This FLAK will be modular, adaptable, scalable, and secure end to end, composed of routable networks, and built entirely from commercial off the shelf technologies (COTS). Basing measures of effectiveness (MOE) on the recently published Quadrennial Defense Report (QDR) and the Numbered Fleet Commanders Communication Message, these kits will be tested with the goal of fulfilling thirteen of the fifteen high priority short-falls in the modern United States CIV-MIL and Coalition Forces' abilities to conduct multiple missions in the current brown (riverine), green (littoral), and blue (deep water) operational theatres. The Maritime FLAK will be designed with the intent of increasing the US forward presence and extending the C4ISR into restricted maritime theatres. Since US forces cannot intervene directly into regions like the Straits of Malacca, but can support coalition forces through advisors and technological adaptations, modular solutions to extend C4ISR into these maritime territories are needed. Furthermore, due to the adaptability and scalability of the technologies to be implemented into the maritime FLAK, these completed kits will be able to be used by the recently formed Naval Expeditionary Combat Command (NECC) in current operations in the Global War on Terrorism. / US Navy (USN) author.

The Coalition Operating Area Surveillance and Targeting System (COASTS) program is a joint project between the Naval Postgraduate School and the Royal Thai Armed Forces (RTARF). The program focuses its research on command, control, communications, computers, intelligence, surveillance and reconnaissance (C4ISR) uses for commercial-off-the-shelf (COTS), state-of-the-art, rapidly scaleable airborne and ground communications equipment, including various wireless network technologies. This research is being conducted in partnership with the RTAF to develop a network and associated devices and applications that potentially may help suppress drug trafficking in the northern Thailand border regions. Commensurately, the U.S. Navy is taking the Global War on Terror (GWOT) lead in coalition Maritime Security Operations and riverine warfare operations. With formation of the new Naval Expeditionary Combat Command (NECC), and its new Riverine Warfare Group, the Navyâ s role takes effect starting in January 2007, and could benefit from this research. This thesis focuses on testing and evaluating the overall performance of the MeshDynamics Multiple-Radio Mesh Modules, operating in the 802.11 wireless frequency spectrum. These modules are key building blocks of meshed networks that provide coverage over an area where riverine and coastal operations are being conducted. The network provides an information source and communications backbone for maritime, ground, and air assets. / US Navy (USN) author.

Chan Chi Pan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves xiv-xv). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Related Works --- p.1 / Chapter 1.3 --- Our Contributions --- p.2 / Chapter 1.4 --- Organization of the Thesis --- p.3 / Chapter Chapter 2 --- Definitions and Assumptions --- p.5 / Chapter 2.1 --- Data-collection Networks --- p.5 / Chapter 2.2 --- Assumptions --- p.9 / Chapter Chapter 3 --- Canonical Networks --- p.13 / Chapter 3.1 --- Theoretical Analysis --- p.13 / Chapter 3.1.1 --- Fixed Link Distance --- p.13 / Chapter 3.1.2 --- Variable Link Distance --- p.17 / Chapter 3.2 --- Simulation --- p.20 / Chapter Chapter 4 --- Beyond the Assumptions --- p.24 / Chapter 4.1 --- Multiple Interference --- p.24 / Chapter 4.2 --- HFD versus non-HFD performance --- p.27 / Chapter Chapter 5 --- Perfect Scheduling and IEEE 802.11 Scheduling --- p.30 / Chapter 5.1 --- Relationship between Perfect Scheduling and IEEE 802.11 Scheduling --- p.30 / Chapter 5.2 --- Throughput Analysis under IEEE 802.11 scheduling --- p.33 / Chapter Chapter 6 --- General Networks --- p.37 / Chapter 6.1 --- Discussion of HFP --- p.37 / Chapter 6.2 --- HFP Formulation --- p.39 / Chapter 6.3 --- Optimization in Finding Best HFP --- p.43 / Chapter 6.4 --- Experiment --- p.44 / Chapter 6.5 --- NS-2 Simulation --- p.47 / Chapter Chapter 7 --- Applying Canonical Network to General Networks --- p.49 / Chapter 7.1 --- Direct Application --- p.49 / Chapter 7.2 --- Manifold Canonical Network with Shorter Link Distance --- p.51 / Chapter 7.3 --- Robustness on Node Positions in Manifold Canonical Network --- p.54 / Chapter Chapter 8 --- Conclusion --- p.56 / Appendix A RTS/CTS and Power Control --- p.x / References --- p.xiv

Wong Tsz-Chun Stanley. / Thesis submitted in: July 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 58-61). / Abstracts in English and Chinese. / 摘要 --- p.III / ACKNOWLEDGEMENT --- p.IV / LIST OF FIGURES --- p.VIII / Chapter CHAPTER 1 --- INTRODUCTION --- p.2 / Chapter 1.1 --- Introduction --- p.2 / Chapter 1.2 --- Organization of the Thesis --- p.6 / Chapter CHAPTER 2 --- BACKGROUND STUDIES --- p.7 / Chapter 2.1 --- Overview of IEEE 802.11 --- p.7 / Chapter 2.3 --- 802.11b Network Type --- p.10 / Chapter 2.4 --- IEEE 802.11 MAC overview --- p.12 / Chapter 2.4.1 --- Distributed Coordination Function (DCF) / Point Coordination Function (PCF) --- p.13 / Chapter 2.4. --- Request-to-Send (RTS) / Clear-to-Send (CTS) --- p.14 / Chapter CHAPTER 3 --- QUEUE MANAGEMENT IN ACCESS POINTS --- p.16 / Chapter 3.1 --- Introduction --- p.16 / Chapter 3.2 --- Packet Delay Variation in Access Points --- p.17 / Chapter 3.2 --- Simulations Settings and Configuration --- p.19 / Chapter 3.2.1 --- Mobile Networking in NS2 --- p.19 / Chapter 3.2.2 --- Input Parameter of Shadowing Radio Propagation model --- p.22 / Chapter 3.2.3 --- Configuration of the simulation --- p.25 / Chapter CHAPTER 4 --- PERFORMANCE ANALYSIS OF 802.11B DOWNLINKS --- p.30 / Chapter 4.1 --- Introduction --- p.30 / Chapter 4.5 --- Assumptions of the analysis --- p.31 / Chapter 4.3 --- Proposed Queue Management in Access Point --- p.32 / Chapter 4.4 --- Channel error modeling --- p.34 / Chapter 4.5 --- The analytical model of downlinks --- p.35 / Chapter 4.6 --- Performance Calculation --- p.37 / Chapter 4.4 --- Simulation Result --- p.41 / Chapter 4.4.1 --- Extension of NS2 --- p.42 / Chapter 4.4.2 --- Configuration of the simulation --- p.44 / Chapter CHAPTER 5 --- RESOURCE ASSIGNMENT IN ACCESS POINTS --- p.48 / Chapter 5.1 --- Introduction --- p.48 / Chapter 5.2 --- Packet Delay Balancing --- p.49 / Chapter 5.2 --- Simulation Result --- p.51 / Chapter CHAPTER 6 --- CONCLUSION --- p.56 / BIBLIOGRAPHY --- p.58

Chen, Darui. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 62-67). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.vii / List of Tables --- p.viii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Related Works --- p.2 / Chapter 1.3 --- Contributions --- p.6 / Chapter 1.4 --- Organization --- p.8 / Chapter Chapter 2 --- Preliminaries --- p.9 / Chapter 2.1 --- MAC Protocol in IEEE 802.11 WLANs --- p.9 / Chapter 2.1.1 --- IEEE 802.11 DCF --- p.9 / Chapter 2.1.2 --- Performance Anomaly of DCF --- p.11 / Chapter 2.2 --- Multi-Rate WLANs with Rate Adaptation --- p.12 / Chapter 2.2.1 --- PHY-Layer Rate Adaptation Model --- p.12 / Chapter 2.2.2 --- Two Typical WLANs with Rate Adaptation --- p.13 / Chapter Chapter 3 --- Performance Analysis and Evaluation of Multi-Rate IEEE802.11 WLANs --- p.15 / Chapter 3.1 --- Theoretical Analysis of Multi-Rate IEEE 802.11 WLANs --- p.15 / Chapter 3.1.1 --- Markov Chain Model for Backoff Process --- p.15 / Chapter 3.1.2 --- Saturation Throughput --- p.18 / Chapter 3.1.3 --- Theoretical Throughput Limit and Dynamic Backoff --- p.20 / Chapter 3.2 --- Performance Evaluation of Multi- Rate WLANs --- p.22 / Chapter 3.2.1 --- Model Validation --- p.22 / Chapter 3.2.2 --- Theoretical Throughput Limit --- p.24 / Chapter Chapter 4 --- Rate-aware DCF Protocol --- p.30 / Chapter 4.1 --- Proposed R-DCF Protocol --- p.30 / Chapter 4.2 --- Theoretical Analysis of R-DCF --- p.34 / Chapter 4.2.1 --- Markov Chain Model for Backoff Process --- p.34 / Chapter 4.2.2 --- Saturation Throughput --- p.36 / Chapter 4.2.3 --- Simplified Models --- p.39 / Chapter 4.3 --- Performance Evaluation --- p.41 / Chapter 4.3.1 --- Model Validation --- p.41 / Chapter 4.3.2 --- R-DCF with Homogeneous Users --- p.42 / Chapter 4.3.3 --- R-DCF in Fixed-Rate WLANs --- p.49 / Chapter Chapter 5 --- Performance Enhancement of the R-DCF Protocol --- p.52 / Chapter 5.1 --- Maximizing Throughput of R-DCF --- p.52 / Chapter 5.2 --- Offline Adaptive Backoff Methods --- p.55 / Chapter Chapter 6 --- Conclusions --- p.60 / Bibliography --- p.62

Chan, An. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 80-84). / Abstracts in Chinese and English. / 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.5 / Chapter 2.1 --- IEEE 802.11 --- p.5 / Chapter 2.1.1 --- Basic IEEE 802.11 Standards --- p.5 / Chapter 2.1.2 --- Types of Networks --- p.7 / Chapter 2.2 --- Voice over IP (VoIP) Codecs --- p.8 / Chapter 2.3 --- VoIP over WLAN --- p.9 / Chapter 2.3.1 --- System Architecture of VoIP over WLAN --- p.9 / Chapter 2.3.2 --- VoIP Capacity over an Isolated WLAN --- p.10 / Chapter Chapter 3 --- VoIP Capacity over Multiple WLANs --- p.12 / Chapter 3.1 --- Topology Settings and Assumptions --- p.12 / Chapter 3.2 --- Low VoIP Capacity Found in NS2 Simulations --- p.16 / Chapter 3.3 --- Applying Frequency Channel Assignment --- p.18 / Chapter Chapter 4 --- Clique Analysis and Call Admission Control --- p.21 / Chapter 4.1 --- Conflict Graph Model and Cliques --- p.21 / Chapter 4.2 --- Cliques in Multi-Cell WLANs --- p.22 / Chapter 4.3 --- Clique-Based Call Admission Control Algorithm --- p.24 / Chapter 4.3.1 --- Algorithm Description --- p.24 / Chapter 4.3.2 --- Algorithm Performance Evaluation --- p.27 / Chapter 4.3.3 --- Clique-Based Admission Control in Three-Frequency- Channel WLAN --- p.29 / Chapter Chapter 5 --- Time Division Multiple Access (TDMA) on IEEE 802.11MAC --- p.32 / Chapter 5.1 --- Coarse-Grained Time-Division Multiple Access (CTDMA) --- p.33 / Chapter 5.1.1 --- Basic Ideas of CTDMA --- p.33 / Chapter 5.1.2 --- Conflict Graph Modeling of CTDMA --- p.35 / Chapter 5.1.3 --- Parameter Values in CTDMA --- p.41 / Chapter 5.2 --- Possible Realization of TDMA on 802.11 Standards --- p.47 / Chapter Chapter 6 --- Coloring Problem in Wireless Networks: A Theoretical Treatment --- p.52 / Chapter 6.1 --- Coloring of One-Dimensional Linear Network --- p.53 / Chapter 6.1.1 --- Network with Same Link Length --- p.53 / Chapter 6.1.2 --- Network with Variable Link Length --- p.54 / Chapter 6.2 --- Coloring of Two-Dimensional Network --- p.63 / Chapter Chapter 7 --- Conclusion --- p.66 / Appendices --- p.69 / References --- p.80