Approved for public release, distribution is unlimited / On the modern battlefield, successful and fast communications is a critical issue. So the need for transmitting information in larger amounts through a military high-speed network increases. Thus the military is seeking viable and effective solutions that may fulfill these requirements in an operational environment. This thesis develops a prototype system based on appropriate low-cost software and hardware solutions. This system is able to detect, analyze and process wireless 802.11g signals. The evaluation of the newly designed system proved that it is effective up to distances of about 400 m with a low packet error rate and could be a useful tool for detecting wireless 802.11g networks. After evaluating the system, it was used for capturing wireless signals so that we would determine the effective transmission range and the data throughput of an 802.11g network. We determined that such a wireless network could be used in military operations because it offers high data rates up to 200 m, while it maintains a connection of the wireless clients for distances up to 400 m. In addition, the performance data collected can be used as guidelines for estimating the expected performance in an operational situation and can provide useful information for successful planning. / Lieutenant, Hellenic Navy

Approved for public release; distribution is unlimited / The way that the Internet is accessed has changed dramatically in recent years. In addition to wire line connections such as dial-up, xDSL, cable modems or optical fiber, wireless implementations are gaining market share based on technologies such as WiFi, WiMAX, MBWA, satellite and cell phone networks. This thesis examines the potential usage of providing Internet access through cellular infrastructure. The cellular evolution path from first generation (1G) to third generation (3G) and fourth generation (4G) systems is studied and presented. The most popular worldwide cellular voice and data network technologies are also described. Additionally, the Cingular Wireless network in Monterey, California is tested in terms of speed and reliability by providing Internet access to a laptop through a mobile phone. The analysis shows that, depending on the cellular network availability, throughput varied from 5 to 25 Kbps and Round Trip Time (RTT) averaged about 1 sec. Furthermore, it is shown that TCP Timestamps and the Explicit Congestion Notification (ECN) were implemented at the end hosts, thus increasing performance. The thesis concludes that as of July 2004, the 2.5G cellular data networks are a reasonable solution for those who need Internet access anywhere that a cell signal is available, including from moving vehicles, and who can afford its high cost. For others it is not yet an acceptable solution. However, the future 3G networks are an excellent solution in wireless broadband Internet access. These will probably be relatively expensive at first, but the cost should eventually decrease to a reasonable level. / Lieutenant, Hellenic Navy

Approved for public release, distribution unlimited / Since wireless technology has been used in Local Area Networks (LAN), our networks are easier to build and are more scalable and mobile than legacy structures. While providing these functionalities, Wireless LAN (WLAN)'s have some security vulnerabilities that should be addressed. Failing to examine the security risks of WLAN technology and take the necessary countermeasures may result in unauthorized entry into the legacy local area networks and other attacks. A secure connection to an intranet, which holds critical data and applications, must be the utmost consideration in the effort to protect critical resources. This thesis builds an open-source test-bed for evaluating WLAN security protocols. Moreover, it investigates the suitability of the IEEE 802.1X standard to provide the required security framework to WLANs. This research determines that the IEEE 802.1X could enhance the security level in authentication and privacy by the enabling rekeying process, but would not prevent Denial of Service attacks via unauthenticated management frames. / Turkish Navy author.

Thesis advisor: Frank Gollop / By November 2003, wireless telecommunications operators were required by the FCC to have implemented wireless number portability. The FCC and the media claimed that this decrease in the cost of switching would force operators to react competitively by either decreasing prices or increasing the services offered at the same price to prevent customers from migrating to competitors. This paper empirically analyzes the effect that this regulation had on plan prices offered by the top four U.S. cellular operators over the period of Q2 2002 through Q2 2008, identifying whether they increased or decreased and by how much. This paper concludes that three out of the four nationwide carriers lowered prices in response to the implementation of wireless number portability. / Thesis (BA) — Boston College, 2013. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Economics Honors Program. / Discipline: College Honors Program. / Discipline: Economics.

Feng, Shen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 84-88). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Zhang Jun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 82-92). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Multipath Fading Channels --- p.1 / Chapter 1.2 --- Diversity --- p.3 / Chapter 1.3 --- Outline of the Thesis --- p.6 / Chapter 2 --- Background and Related Work --- p.8 / Chapter 2.1 --- Cooperative Diversity --- p.8 / Chapter 2.1.1 --- User Cooperation --- p.9 / Chapter 2.1.2 --- Cooperative Diversity --- p.10 / Chapter 2.1.3 --- Coded Cooperation --- p.12 / Chapter 2.2 --- Information-Theoretic Studies --- p.13 / Chapter 2.3 --- Multihop Cellular Networks --- p.15 / Chapter 2.3.1 --- MCN: Multihop Cellular Network --- p.15 / Chapter 2.3.2 --- iCAR: Integrated Cellular and Ad Hoc Relaying Systems --- p.17 / Chapter 2.3.3 --- UCAN: Unified Cellular and Ad Hoc Network Architecture --- p.17 / Chapter 2.4 --- Wireless Ad Hoc Networks --- p.18 / Chapter 2.5 --- Space-Time Processing --- p.20 / Chapter 3 --- Single-Source Multiple-Relay Cooperation System --- p.23 / Chapter 3.1 --- System Model --- p.23 / Chapter 3.2 --- Fixed Decode-and-Forward Cooperation System --- p.26 / Chapter 3.2.1 --- BER for system with errors at the relay --- p.28 / Chapter 3.2.2 --- General BER formula for single-source nr-relay cooperation system --- p.30 / Chapter 3.2.3 --- Discussion of Interuser Channels --- p.31 / Chapter 3.3 --- Relay Selection Protocol --- p.33 / Chapter 3.3.1 --- Transmission Protocol --- p.34 / Chapter 3.3.2 --- BER Analysis for Relay Selection Protocol --- p.34 / Chapter 4 --- Multiple-Source Multiple-Relay Cooperation System --- p.40 / Chapter 4.1 --- Transmission Protocol --- p.41 / Chapter 4.2 --- Fixed Cooperative Coding System --- p.43 / Chapter 4.2.1 --- Performance Analysis --- p.43 / Chapter 4.2.2 --- Numerical Results and Discussion --- p.48 / Chapter 4.3 --- Adaptive Cooperative Coding --- p.49 / Chapter 4.3.1 --- Performance Analysis of Adaptive Cooperative Coding System --- p.50 / Chapter 4.3.2 --- Analysis of p2(2) --- p.52 / Chapter 4.3.3 --- Numerical Results and Discussion --- p.53 / Chapter 5 --- Cooperative Multihop Transmission --- p.56 / Chapter 5.1 --- System Model --- p.57 / Chapter 5.1.1 --- Conventional Multihop Transmission --- p.58 / Chapter 5.1.2 --- Cooperative Multihop Transmission --- p.59 / Chapter 5.2 --- Performance Evaluation --- p.59 / Chapter 5.2.1 --- Conventional Multihop Transmission --- p.60 / Chapter 5.2.2 --- Cooperative Multihop Transmission --- p.60 / Chapter 5.2.3 --- Numerical Results --- p.64 / Chapter 5.3 --- Discussion --- p.64 / Chapter 5.3.1 --- Cooperative Range --- p.64 / Chapter 5.3.2 --- Relay Node Distribution --- p.67 / Chapter 5.3.3 --- Power Allocation and Distance Distribution (2-hop Case) --- p.68 / Chapter 5.4 --- Cooperation in General Wireless Ad Hoc Networks --- p.70 / Chapter 5.4.1 --- Cooperation Using Linear Network Codes --- p.71 / Chapter 5.4.2 --- Single-Source Single-Destination Systems --- p.74 / Chapter 5.4.3 --- Multiple-Source Single-Destination Systems --- p.75 / Chapter 6 --- Conclusion --- p.80 / Bibliography --- p.82 / Chapter A --- Proof of Proposition 1-4 --- p.93 / Chapter A.1 --- Proof of Proposition 1 --- p.93 / Chapter A.2 --- Proof of Proposition 2 --- p.95 / Chapter A.3 --- Proof of Proposition 3 --- p.95 / Chapter A.4 --- Proof of Proposition 4 --- p.96

Wang Wei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 80-83). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations and Contributions --- p.1 / Chapter 1.2 --- Organization of the Thesis --- p.4 / Chapter Chapter 2 --- Background --- p.6 / Chapter 2.1 --- IEEE 802.11 --- p.6 / Chapter 2.1.1 --- Distributed Coordination Function (DCF) / Point Coordination Function (PCF) --- p.7 / Chapter 2.1.2 --- Types of Networks --- p.8 / Chapter 2.1.3 --- The 802.11 MAC Sublayer Protocol --- p.9 / Chapter 2.1.4 --- Why CSMA/CA for Wireless LAN? --- p.11 / Chapter 2.2 --- Voice over IP (VoIP) --- p.13 / Chapter 2.2.1 --- Speech Codec --- p.13 / Chapter 2.2.2 --- The H.323 Standard --- p.13 / Chapter 2.3 --- Related Work --- p.15 / Chapter 2.3.1 --- Capacity limits of VoIP over WLAN --- p.16 / Chapter 2.3.2 --- Methods for increasing VoIP capacity over WLAN --- p.16 / Chapter 2.3.3 --- Interference between traffic of VoIP and other applications --- p.18 / Chapter Chapter 3 --- VoIP Multiplex-Multicast Scheme --- p.20 / Chapter 3.1 --- System Architecture --- p.20 / Chapter 3.2 --- Packet Multiplexing and Multicasting --- p.22 / Chapter 3.3 --- Header Compression --- p.24 / Chapter 3.4 --- Connection Establishment --- p.29 / Chapter Chapter 4 --- Capacity Analysis --- p.31 / Chapter 4.1 --- VoIP Capacity Analysis for 802. 11b --- p.31 / Chapter 4.1.1 --- Capacity of Ordinary VoIP over WLAN --- p.32 / Chapter 4.1.2 --- Capacity of Multiplex-Multicast Scheme over WLAN --- p.33 / Chapter 4.2 --- "VoIP Capacity Analysis for 802,11a and 802.11g" --- p.34 / Chapter 4.3 --- VoIP Capacity with VBR Sources --- p.38 / Chapter 4.4 --- Simulations --- p.38 / Chapter Chapter 5 --- Delay Performance --- p.41 / Chapter 5.1 --- Access Delay --- p.42 / Chapter 5.2 --- Extra Delay Incurred by the Multiplex-Multicast Scheme --- p.47 / Chapter Chapter 6 --- VoIP Co-existing with TCP Interference Traffic --- p.49 / Chapter 6.1 --- Ordinary VoIP co-existing with TCP over WLAN --- p.49 / Chapter 6.1.1 --- Problem Caused by TCP Interference --- p.49 / Chapter 6.1.2 --- Solutions --- p.52 / Chapter 6.2 --- M-M VoIP coexisting with TCP over WLAN --- p.53 / Chapter 6.3 --- 802.11e --- p.56 / Chapter 6.3.1 --- EDCA --- p.56 / Chapter 6.3.2 --- ACK Policies --- p.58 / Chapter 6.3.3 --- VoIP over EDCA --- p.58 / Chapter Chapter 7 --- Experimental Validation --- p.61 / Chapter 7.1 --- Transmission Errors --- p.61 / Chapter 7.2 --- Prototype Implementation --- p.62 / Chapter Chapter 8 --- VoIP over Ad Hoc Networks --- p.65 / Chapter 8.1 --- Mobile Ad Hoc Networks (MANET) and Wireless Distributed System (WDS) --- p.65 / Chapter 8.2 --- The M-M Scheme in WDS --- p.67 / Chapter 8.2.1 --- Modified System Architecture --- p.67 / Chapter 8.2.2 --- Delay Performance --- p.68 / Chapter 8.2.3 --- Analysis of M-M Scheme in WDS --- p.69 / Chapter 8.2.4 --- Capacity Improvement --- p.70 / Chapter 8.2.5 --- Delay Improvement --- p.71 / Chapter 8.2.6 --- Spectrum Reuse --- p.71 / Chapter Chapter 9 --- Conclusions --- p.76 / References --- p.80

In the first part of this thesis, we focus on Drive-thru Internet systems where access points (AP) are placed on roadsides and vehicles passing through the coverage range of the APs can download data from them. The amount of data downloaded by an individual user is affected not only by the scheduling algorithms, but also by the user dynamics, i.e. the movement of the vehicles which impacts the amount of time the vehicle spends in the AP's coverage range, as well as the number of contending vehicles for the AP's resources. We have developed practical analytical models with tractable solutions to characterize the data communication performance of a vehicle in a Drive-thru Internet system. A distinctive aspect of our models is that they combined both vehicular traffic theory and wireless network/protocol properties to investigate the effects of various system parameters on a drive-thru vehicle's data communication performance. / In the second part of this thesis, we examine resource sharing in wireless sensor networks in terms of the node access to the wireless medium. We propose an energy-efficient TDMA-based MAC protocol that significantly reduces energy consumption in the network, while efficiently handling network traffic load variations and optimizing channel utilization through a timeslots stealing mechanism and timeslots reassignment procedure. We have analytically derived the average delay performance of our MAC protocol, with and without the timeslots stealing feature. Our delay model, validated via simulations, shows that the timeslots stealing feature can substantially improve the protocol throughput in situations with varying and asymmetric traffic patterns. Simulation results show that the timeslots reassignment procedure is efficient in handling the longer timescale changes in the traffic load, while the timeslots stealing mechanism is better in handling the shorter timescale changes in the traffic patterns. / In wireless networks, the efficient sharing of scarce wireless spectral resources is important in order to provide guaranteed Quality-of-Service (QoS) to the wireless users. The effectiveness of resource sharing schemes in wireless networks are often heavily influenced by different aspects of the system behavior, such as user mobility, traffic dynamics and practical realization constraints. In this thesis, using analytical modeling and empirical measurement techniques, we investigate the impact of these system behaviors on the performance of resource sharing in wireless networks. In particular, we investigate the dynamic sharing of an access point's bandwidth resources among moving vehicles in a vehicular network, the adaptive sharing of the medium access resources among nodes with different and varying traffic loads in a wireless sensor network, and the practical implementation of network resources sharing among users and applications with different QoS requirements in 3G wireless networks. / The third part of this thesis focuses on our empirical investigations into the performance of practical implementation of resource sharing schemes in 3G wireless networks. We have investigated the performance of multiple commercial 3G networks in Hong Kong, in terms of their ability to provide service guarantees to different traffic classes as well as the fairness of the radio-link scheduler in allocating the bandwidth resources to multiple data calls in a saturated network. We have also investigated the data throughput, latency, video and voice calls handling capacities of the 3G networks under saturated network conditions. Our findings point to the diverse nature of the network resources allocation mechanisms and the call admission control policies adopted by different operators. Our results also show that the 3G network operators seem to have extensively customized their network configurations in a cell-by-cell manner according to the individual site's local demographics, projected traffic demand and the target coverage area of the cell. As such, the cell capacity varies widely not only across different operators but also across different measurement sites of the same operator. / by Tan, Wee Lum. / Adviser: Wing Cheong Lau. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 129-138). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

First, we give the first formal study on stream control scheduling in wireless mesh networks with Multi-Input-Multi-Output (MIMO) antennas and study how much it can improve network capacity. We derive the upper bound of the optimal network capacity gain of stream control. We also propose an efficient stream control scheduling algorithm, GreedySC. Simulations show the network capacity of GreedySC is much larger than that of a previously proposed stream control scheduling algorithm, SCMA. / Second, we consider leveraging transmission power to improve the network capacity of wireless mesh networks. It is well-known that power control can improve network capacity significantly. However, recent works show conflicting results: network capacity may increase or decrease with higher transmission power under different scenarios. In this work, we give the first systematic study on this paradox. We prove that the the optimal network capacity is a non-decreasing function of higher transmission power. We also derive the upper bound of the optimal network capacity gain of power control. Finally, we give the reasons why network capacity may increase or decrease with higher transmission power in practice. Simulations verify our arguments. / The next generation wireless networks target at providing better quality of service for ubiquitous network access than nowaday wireless networks. Various technologies from the physical layer to the transport layer are proposed to realize this goal. A fundamental question is how to characterize the impact of a new technology on the performance of wireless networks, e.g., network capacity, backlog and delay. We propose to apply optimization theory for the network capacity characterization and apply stochastic network calculus for the backlog and delay characterization. However, the detailed characterization procedure depends on different problems. In this thesis, we first formally define network capacity, the (optimal) network capacity gain of a new technology, backlog and delay. Then we carry out systematic characterizations on the following three important issues in designing the next generation wireless networks. / Third, we take the first step to apply stochastic network calculus for the backlog and delay analysis of 802.11 wireless local networks. We prove the general stability condition of deriving stable backlog and delay for a wireless node. From this, we derive the specific stability condition of an 802.11 wireless node. Then we derive the stochastic service curve of an 802.11 node. Based on the service curve, we derive the backlog and delay bounds of the node. Simulations verify our analysis. / Wang, Yue. / Adviser: John C. S. Lui. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 109-117). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

In modern communication systems, the rate of transmitted data is growing rapidly. This leads to the need for more sophisticated methods and techniques of implementation in every block of the transmitter-receiver chain. The weakest link in radio communications is the transmission channel. The signal, which is passed through it, suffers from many degrading factors like noise, attenuation, diffraction, scattering etc. In the receiver side, the modulated signal has to be restored to its initial state in order to extract the useful information. Assuming that the channel acts like a filter with finite impulse, one has to know its coefficients in order to apply the inverse function, which will restore the signal back to its initial state. The techniques which deal with this problem are called channel estimation. Noise is one of the causes that degrade the quality of the received signal. If it could be discarded, then the process of channel estimation would be easier. Transmitting special symbols, called pilots with known amplitude, phase and position to the receiver and assuming that the noise has zero mean, an averaging process could reduce the noise impact to the pilot amplitudes and thus simplify the channel estimation process. In this thesis, a novel channel estimation method based on noise rejection is introduced. The estimator takes into account the time variations of the channel and adapts its buffer size in order to achieve the best performance. Many configurations of the estimator were tested and at the beginning of the research fixed size estimators were tested. The fixed estimator has a very good performance for channels which could be considered as stationary in the time domain, like Additive White Gaussian Noise (AWGN) channels or slowly time-varying channels. AWGN channel is a channel model where the only distorting factor is the noise, where noise is every unwanted signal interfering with the useful signal. The properties of the noise are that it is additive, which means that the noise is superimposed on the transmitted signal, it is white so the power density is constant for all frequencies, and it has a Gaussian distribution in the time domain with zero mean and variance σ2=N. A slowly time varying channel refers to channel with coherence time larger than the transmitted symbol duration. The performance of a fixed size averaging estimator in case of fast time-varying channels is subject to the buffering time. When the buffering time is smaller or equal to a portion of the coherence time the averaging process offers better performance than the conventional estimation, but when the buffering time exceeds this portion of the coherence time the performance of the averaging process degrades fast. So, an extension has been made to the averaging estimator that estimates the Doppler shift and thus the coherence time, where the channel could be assumed as stationary. The improved estimator called Adaptive Averaging Channel Estimator (AACE) is capable to adjust its buffer size and thus to average only successive Orthogonal Frequency Division Multiplexing (OFDM) symbols that have the same channel distortions. The OFDM is a transmission method where instead of transmitting the data stream using only on carrier, the stream is divided into parallel sub-streams where the subcarriers conveying the sub-streams are orthogonal to each other. The use of the OFDM increases the symbol duration making it more robust against Inter-Symbol Interference (ISI), which the interference among successive transmitted symbols, and also divides the channel bandwidth into small sub-bandwidths preventing frequency selectivity because of the multipath nature of the radio channel. Simulations using the Rayleigh channel model were performed and the results clearly demonstrate the benefits of the AACE in the channel estimation process. The performance of the combination of AACE with Least Square estimation (AACE-LS) is superior to the conventional Least Square estimation especially for low Doppler shifts and it is close to the Linear Minimum Mean Square Error (LMMSE) estimation performance. Consequently, if the receiver has low computational resources and/or the channel statistics are unknown, then the AACE-LS estimator is a valid choice for modern radio receivers. Moreover, the proposed adaptive averaging process could be used in any OFDM system based on pilot aided channel estimation. In order to verify the superiority of the AACE algorithm, quantitative results are provided in terms of BER vs SNR. It is demonstrated that AACE-LS is 7dB more sensitive than the LS estimator.