Hung, Kwok-Wah. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1991. / Bibliography: leaves 109-111. / ACKNOWLEDGEMENTS / ABSTRACT / Chapter CHAPTER 1 --- Overview of Packet Radio Networks --- p.1 / Chapter 1.1 --- Introduction --- p.2 / Chapter 1.2 --- Network Structure --- p.3 / Chapter 1.3 --- Channel Access Protocol --- p.3 / Chapter 1.4 --- Spatial Reuse --- p.5 / Chapter 1.5 --- Spread Spectrum --- p.6 / Chapter 1.6 --- Thesis Introduction --- p.8 / Chapter CHAPTER 2 --- Design Algorithms for Networks with Directional Antennas --- p.12 / Chapter 2.1 --- Introduction --- p.13 / Chapter 2.2 --- Problems in The MTCD/MDA Protocol --- p.14 / Chapter 2.3 --- The Simple Tone Sense (STS) Protocol --- p.15 / Chapter 2.4 --- The Variable Power Tone Sense (YPTS) Protocol --- p.18 / Chapter 2.5 --- Network Design Algorithms --- p.19 / Chapter 2.6 --- Network Design Example --- p.25 / Chapter 2.7 --- Simulation Results --- p.28 / Chapter 2.8 --- Chapter Summary --- p.31 / Chapter CHAPTER 3 --- The Coded Tone Sense Protocol --- p.44 / Chapter 3.1 --- Introduction … --- p.45 / Chapter 3.2 --- System Model and Code Assignment Algorithm --- p.46 / Chapter 3.3 --- Protocol Description --- p.48 / Chapter 3.4 --- Simulation Results --- p.49 / Chapter 3.5 --- Chapter Summary --- p.51 / Chapter CHAPTER 4 --- An Efficient Spreading Code Assignment Algorithm --- p.54 / Chapter 4.1 --- Introduction … --- p.55 / Chapter 4.2 --- Code Assignment and Graph Coloring --- p.55 / Chapter 4.3 --- Algorithm Description --- p.57 / Chapter 4.4 --- Results and Discussion --- p.59 / Chapter 4.5 --- Chapter Summary --- p.60 / Chapter CHAPTER 5 --- Fair and Efficient Transmission Scheduling --- p.64 / Chapter 5.1 --- Introduction --- p.65 / Chapter 5.2 --- The Scheduling Problem --- p.67 / Chapter 5.3 --- The Scheduling Algorithm --- p.68 / Chapter 5.4 --- Performance Analysis --- p.70 / Chapter 5.5 --- Results and Discussion --- p.72 / Chapter 5.6 --- Chapter Summary --- p.74 / Chapter CHAPTER 6 --- Staggered Multicast Protocol with Collision-Free Acknowledgement --- p.79 / Chapter 6.1 --- Introduction --- p.80 / Chapter 6.2 --- System Model --- p.83 / Chapter 6.3 --- Protocol Description --- p.84 / Chapter 6.4 --- Staggered Relay Broadcasting --- p.90 / Chapter 6.5 --- Simulation Results --- p.91 / Chapter 6.6 --- Chapter Summary --- p.92 / Chapter CHAPTER 7 --- Conclusion --- p.104 / Chapter 7.1 --- Summary --- p.105 / Chapter 7.2 --- Topics for Future Research --- p.107 / REFERENCES --- p.109

No description available.

The problem of data transmission in a packet radio system with one central base station and a number of mobile/stationary terminals is addressed. More specifically, the effects of possible collisions between packets on the inbound channel are investigated. Schemes which can be used to improve the performance are studied. The use of capture to improve the performance of slotted ALOHA systems is discussed. For a power group division scheme proposed by Metzner in which a capture effect is artificially induced, it is shown that in the two power group case, the higher power packet needs only be able to tolerate interference from up to three lower power packets in order to realize most of the achievable improvement of the infinite capture model. The evaluation of the performance for more than two power groups is also considered. A packet radio system in which a capture effect exists due to the fact that mobiles will generally be at different distances from the base station is also investigated. A number of different capture and spatial distribution models are discussed. Methods for evaluating the probability [formula omitted] of successful reception when there are [formula omitted] contending transmitters are examined. It is shown that a generalized capture model can be used to estimate [formula omitted] for an example system which uses non-coherent frequency shift keying modulation. This model can be applied to other systems as well. In most practical systems, the mobiles cannot get arbitrarily close to the base station. The effects of this constraint on [formula omitted] is examined. The dependence of the capture probability for a test mobile on its distance from the base station is also analyzed. The use of multiple directional antennas and receivers in a slotted ALOHA system in which the signals from the different transmitters are received with more or less the same powers is analyzed. It is shown that the performance of the system can be substantially improved by using directional antennas and multiple receivers. Results indicate that fewer than five antennas per receiver are required in order to achieve most of the achievable performance. A finite population Markov model is used to evaluate the performance of a multi-antenna and receiver slotted ALOHA system in a mobile radio environment in which the signal power levels from different mobiles are no longer equal. The effects of three different antenna patterns, background noise and Rayleigh fading are studied. Here again, numerical results indicate that substantial gains are possible with the use of several antennas and receivers. It is also found that the dynamic behaviour of the system is improved. The selection of the antennas to be connected to the receivers becomes an issue if the number of receivers at the base station is less than the number of antennas . Four antenna selection schemes are compared for three different channel models, assuming an ideal antenna pattern. It is found that the scheme which selects the antennas with the largest received signal powers is nearly optimum. The effects of using a more practical non-ideal antenna pattern are also discussed. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Yuen Ching Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 77-83). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Nature of Real-Time Traffic --- p.1 / Chapter 1.2 --- Delay Variability in Wireless Networks --- p.2 / Chapter 1.2.1 --- Propagation Medium --- p.3 / Chapter 1.2.2 --- Impacts of Network Designs --- p.5 / Chapter 1.3 --- The Keys - Packet Lifetime & Channel State --- p.8 / Chapter 1.4 --- Contributions of the Thesis --- p.8 / Chapter 1.5 --- Organization of the Thesis --- p.9 / Chapter 2 --- Background Study --- p.11 / Chapter 2.1 --- Packet Scheduling --- p.12 / Chapter 2.2 --- Call Admission Control (CAC) --- p.12 / Chapter 2.3 --- Active Queue Management (AQM) --- p.13 / Chapter 2.3.1 --- AQM for Wired Network --- p.14 / Chapter 2.3.2 --- AQM for Wireless Network --- p.17 / Chapter 3 --- Intelligent Packet Discarding Policies --- p.21 / Chapter 3.1 --- Random Packet Discard --- p.22 / Chapter 3.1.1 --- Variable Buffer Limit (VABL) --- p.22 / Chapter 3.2 --- Packet Discard on Expiration Likelihood (PEL) --- p.23 / Chapter 3.2.1 --- Working Principle --- p.24 / Chapter 3.2.2 --- Channel State Aware Packet Discard on Expiration Likelihood (CAPEL) --- p.26 / Chapter 3.3 --- System Modeling --- p.29 / Chapter 3.3.1 --- Wireless Channel as an Markov-Modulated Poisson Process (MMPP) --- p.30 / Chapter 3.3.2 --- System Analysis --- p.30 / Chapter 3.3.3 --- System Time Distribution --- p.33 / Chapter 3.3.4 --- Approximation of System Time Distribution by Gamma Distribution --- p.36 / Chapter 3.4 --- Goodput Analysis of Intelligent Packet Discarding Policies --- p.38 / Chapter 3.4.1 --- Variable Buffer Limit (VABL) --- p.38 / Chapter 3.4.2 --- CAPEL at the End-of-Line --- p.39 / Chapter 3.4.3 --- CAPEL at the Head-of-Line --- p.43 / Chapter 4 --- Performance Evaluation --- p.44 / Chapter 4.1 --- Simulation --- p.44 / Chapter 4.1.1 --- General Settings --- p.45 / Chapter 4.1.2 --- Choices of Parameters --- p.46 / Chapter 4.1.3 --- Variable Buffer Limit (VABL) --- p.49 / Chapter 4.1.4 --- CAPEL at the End-of-Line --- p.53 / Chapter 4.1.5 --- CAPEL at the Head-of-Line --- p.60 / Chapter 4.2 --- General Discussion --- p.64 / Chapter 4.2.1 --- CAPEL vs RED --- p.64 / Chapter 4.2.2 --- Gamma Approximation for System Time Distribution . --- p.69 / Chapter 5 --- Conclusion --- p.70 / Chapter A --- Equation Derivation --- p.73 / Chapter A.l --- Steady State Probabilities --- p.73 / Bibliography --- p.77

Due to the rapid growth of wireless technology, there has been a growing interest in the capabilities of ad hoc networks connecting mobile phones, PDAs and laptop computers. The distributed and self-configurable capabilities of ad hoc networks make them very attractive for some applications such as tactical communication for military, search and rescue mission, disaster recovery, conferences, lectures, etc. In this thesis, we describe several new time scheduling algorithms for multihop packet radio networks; MaxThrou, MinDelay, ECTS (Energy Conserving Transmission Scheduling) and LA-TSMA (Location-Aided Time-Spread Multiple-Access). The MaxThrou and MinDelay algorithms focus on maximizing the system throughput and minimizing the delay bound by using constant weight codes. In these algorithms, each mobile host is assigned a word from an appropriate constant weight code of length n, distance d and weight w. The host can send a message at the j[superscript th] slot provided the assigned code has a 1 in this j[superscript th] bit. The MaxThrou and MinDelay scheduling algorithms are better than the previously known algorithms in terms of the minimum throughput per node and/or the delay bound. Since most of mobile hosts are operated using the scarce battery, and the battery life is not expected to increase significantly in the near future, energy efficiency is a critical issue in ad hoc networks. The ECTS algorithm conserves the power using strategies that allow the network interface to use the low power sleep mode instead of the idle mode, and also eliminates data collisions by introducing Request-To-Send (RTS) and Clear-To-Send (CTS) control slots. Simulation study shows that the ECTS algorithm outperforms previously known protocols. Due to the increasing popularity of mobile networking systems, the scalability becomes a significant new challenge for ad hoc network protocols. To provide a scalable solution for mobile ad hoc networks, we introduce the LA-TSMA algorithm. Instead of assigning a globally unique TSV to each host as done in previous topology-transparent scheduling algorithms, the proposed algorithm assigns a locally unique TSV to each host. In LA-TSMA, a territory is divided into zones, and the mobile hosts located in different zones can be assigned the same TSV. / Graduation date: 2003

The continuous growth in wireless networks is not showing any sign of slowing down as new services, new technologies and new mobile users continue to emerge. Satellite networks are expected to complement the terrestrial network and be a valid option to provide broadband communications services to both fixed and mobile users in scenarios where terrestrial networks cannot be used due to technical and economical viability. In the current emerging satellite networks, where different users with varying traffic demands ranging from multimedia, voice to data and with limited capacity, Radio Resource Management (RRM) is considered as one of the most significant and challenging aspect needed to provide acceptable quality of service that will meet the requirements of the different mobile users. This dissertation considers Packet Scheduling in the Satellite High Speed Downlink Packet Access (S-HSDPA) network. The main focus of this dissertation is to propose a new cross-layer designed packet scheduling scheme, which is one of the functions of RRM, called Queue Aware Channel Based (QACB) Scheduler. The proposed scheduler, which, attempts to sustain the quality of service requirements of different traffic requests, improves the system performance compared to the existing schedulers. The performance analysis comparison of the throughput, delay and fairness is determined through simulations. These metrics have been chosen they are three major performance indices used in wireless communications. Due to long propagation delay in HSDPA via GEO satellite, there is misalignment between the instantaneous channel condition of the mobile user and the one reported to the base station (Node B) in S-HSDPA. This affects effectiveness of the channel based packet schedulers and leads to either under utilization of resource or loss of packets. Hence, this dissertation investigates the effect of the introduction of a Signal-to-Noise (SNR) Margin which is used to mitigate the effect of the long propagation delay on performance of S-HSDPA, and the appropriate SNR margin to be used to achieve the best performance is determined. This is determined using both a semi-analytical and a simulation approach. The results show that the SNR margin of 1.5 dB produces the best performance. Finally, the dissertation investigates the effect of the different Radio Link Control (RLC) Transmission modes which are Acknowledged Mode (AM) and Unacknowledged Mode (UM) as it affects different traffic types and schedulers in S-HSDPA. Proportional fair (PF) scheduler and our proposed, QACB, scheduler have been considered as the schedulers for this investigation. The results show that traffic types are sensitive to the transmitting RLC modes and that the QACB scheduler provides better performance compared to PF scheduler in the two RLC modes considered. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / The use of emerging microprocessors has become increasingly popular in packet radio communication equipment. This is mainly because of the improved performance and hardware simplicity they offer. The new generation field programmable gate arrays (FPGAs) and microcontrollers are now widely used in the development of terminal node controller (TNC) components. The aim of this thesis is to evaluate the use of these new generation FPGAs and microcontrollers in a TNC design, in order to utilise the software flexibility and hardware simplicity. The design process began with the selection of the available simple microcontroller-based modem that was just designed. Prior to its usage in a TNC, the software of the modem was modelled, in order to understand its signal processing functionality.

Amateur Packet Radio Networking presently uses the NET/ROM protocol to establish the network. NET/ROM is considered to be insufficient to support the expected growth of the network. This research work proposes to use the TCP/IP protocol suite instead to build the network. A comparison between features of both protocols supports this proposal. A new and simple hardware platform is introduced. This will provide adequate support for initial experiments. Design considerations for both hardware architecture and software architecture are discussed in detail. Implementation of the IP protocol used for routing is discussed. / Graduation date: 1992

An ad hoc network is a multi-hop wireless network in which mobile nodes communicate over a shared wireless channel. The network is formed cooperatively without specific user administration or configuration and is characterised by a distributed network management system and the absence of a wired backbone. Military, law enforcement, and disaster relief operations are often carried out in situations with no pre-existing network infrastructure and can benefit from such networks because base stations, which are single points of failure, are undesirable from a reliability standpoint. The rising popularity of mobile computing has also created a potentially large commercial market for multimedia applications applied over wireless ad hoc networks. This dissertation focuses on the routing aspects of ad hoc networking. The multi-hop routes between nodes constantly change as the mobile nodes migrate. Ad hoc network routing algorithms must therefore adapt to the dynamic and unpredictable topology changes, the random radio propagation conditions and portable power sources. Various routing protocols have been proposed in the literature for ad hoc networks. These protocols together with comparative simulations are discussed and a new protocol based on load balancing and signal quality determination is proposed . and the simulation results are presented. Currently the proposed routing protocols are compared using simulation packages which are often time consuming. This dissertation proposes a mathematical model for evaluating the routing protocols and the resultant end-to-end blocking probabilities. The mathematical model is based on a derivation of the reduced load approximation for analysing networks modelled as loss networks and the evaluation incorporates and adapts models that have been used for the analysis of cellular Code Division Multiple Access (CDMA) systems. While analytical methods of solving blocking probability can potentially generate results orders of magnitude faster than simulation, they are more importantly essential to network sensitivity analysis, design and optimisation. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

Priority schemes employing the inherent properties of carrier-sense multiple-access (CSMA) schemes are investigated and then applied to the integrated transmission of voice and data. A priority scheme composed of 1-persistent and non-persistent CSMA protocols is proposed. The throughput and delay characteristics of this protocol are evaluated by mathematical analysis and simulation, respectively. The approach of throughput analysis is further extended to another more general case, p-persistent CSMA with two persistency factors, the throughput performance of which had not been analyzed before. Simulations are carried out to study the delay characteristics of this protocol. After careful consideration of the features of the priority schemes studied, two protocols are proposed for integrated voice and data transmission. While their ultimate purpose is for integrated services, they have different application. One of them is applied to local area network; the other is suitable for packet radio network. The distinctive features of the former are simplicity and flexibility. The latter is different from other studies in that collision detection is not required, and that it has small mean and variance of voice packet delay. Performance characteristics of both of these protocols are examined by simulations under various system parameter values. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate