Reachability analysis is one of the earliest and most common techniques for protocol validation. It is well suited to checking the protocol syntactic properties since they are a direct consequence of the structure of the reachability tree. However, validations of unbounded protocols via reachability analysis always lead to the "state explosion" problem. To overcome this, a new approach in reachability analysis has been proposed by Vuong et al [Vuong 82a, 83a]. While not loosing any information on protocol syntactic properties, the Teachability tree constructed by the new approach for all non-FIFO and for a particular set of FIFO protocols (called well-ordered protocols) will become finite. This thesis is concerned with the implementation of an integrated package called VALIRA (VALIdation via Reachability Analysis) which bases on both the proposed technique and the conventional technique. Details and implementation of the various approaches used in VALIRA are presented in order to provide an insight to the package. Various features of the package are demonstrated with examples on different types of protocols, such as the FIFO, the non-FIFO, and the priority protocols. The use of VALIRA was found to be practical in general, despite some limitations of the package. Further enhancements on the VALIRA are also suggested. / Science, Faculty of / Computer Science, Department of / Graduate

Unidirectional broadcast structures constitute a class of high performance local network architectures. They are very flexible and well suited for fiber optic implementation. The access methods used in these networks are often based on certain implicit token-passing mechanisms to provide superior delay-vs-throughput characteristics. The performance of these unidirectional broadcast protocols is evaluated in this thesis via a study on the classical token-ring system. Emphasis is placed on the analysis of mean delay-vs-throughput performance for the gated exhaustive service discipline under asymmetric traffic. The analysis involves examination of the statistical behaviour of interacting queues. A number of exact results are derived and based on these results, a very good approximation for the average delays is developed. The approximation agrees closely with exact numerical solutions over a wide range of system parameters. The implications of the approximation are also discussed. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This thesis presents the development and implementation of two fundamental communication sublayers, medium access and logical link, for a new Local Area Network (LAN) which utilizes the intra-building power distribution circuit as physical transmission medium. This medium provides a low cost means for data communications with a high degree of portability. A low-to-medium data rate and a relatively high error rate are two of the major disadvantages associated with the use of the medium. The Logical Link Control (LLC) protocol adopted is a modified version of the IEEE 802.2 protocol; whereas, the Medium Access Control (MAC) protocol used is a simple hub polling scheme. For efficiency reason, both LLC and MAC sublayers are implemented in the kernel of the UNIX¹ operating system. The schemes used, justifications for the decisions made and their implementations are discussed in details in the thesis. The performance of the power line LAN formed with four Sun workstations² using modems with a data rate of 14.4 kilo-bit per second is measured and analyzed. ¹UNIX is a trademark of AT & T Bell laboratories. ²Sun workstation is a trademark of Sun Microsystems. / Science, Faculty of / Computer Science, Department of / Graduate

A high-speed local area communication network--the Expressnet--is investigated in this thesis with regard to voice and data transmissions. Performance criteria, such as channel utilizations, delay characteristics, and queue lengths are determined from computer simulation and numerical calculation approaches. The protocol is particularly suitable for the transmission of packetized voice as it is able to guarantee an upper bound on the transmission delay for each packet. The network under study thus will find major application in future office automation, where large amounts of voice will be integrated with data. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

A wireless mesh network (WMN) is a multihop wireless network consisting of a large number of wireless nodes of which some are called gateway nodes and connected with a wired network. Wireless mesh network have attracted much research attention recently due to its flexibility, low-cost and robustness, which facilitate its usability in many potential applications, including last-mile broadband Internet access, neighborhood gaming, Video-on-Demand (VoD), distributed file backup, video surveillance, etc. The broadcast nature, the lack of infrastructure as well as the flexible deployment nature of wireless mesh networks make it different from wired networks, therefore more attention in designing the wireless mesh network is needed to maintain a good performance of this promising technology. We, in this study, investigate the wireless mesh network design taking into consideration three design factors seeking an improvement in the network performance by reducing the interference influence in the network, improving the network reliability to satisfy more requests, and securing the network against malicious eavesdropping attacks. Our design is presented into three sub-problems; sub-problem (1), which seeks an interference-aware robust topology control scheme, sub-problem (2) which seeks a multipath routing scheme, and sub-problem (3) which seeks a secure key management scheme. Through simulations and comparisons with previous work, we show that our proposed solutions outperform previous schemes in providing a better network performance in terms of reducing the network interference, satisfying more number of requests and increasing the network resistance to malicious eavesdropping attacks.

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This report reviews the subject of multiprocessor/multicomputer systems and optimal loading techniques. This report covers: 1. The interrelationship of Multiprocessor/Multicomputer (Multiple Instruction Stream Multiple Data Stream, MIMD) systems and other architectures by presenting a categorization of computer architectures. 2. Comparison of Multiprocessor/Multicomputer (MIMD), versus Parallel Processor (Single Instruction stream Multiple Data stream, SIMD) systems. 3. Multiprocessor/Multicomputer problems, pitfalls and new goals. 4. Investigation of loading techniques by reviewing particular MIMD executive designs.

Thesis (M.S.)--The University of North Carolina at Greensboro, 2008. / Directed by Shan Suthaharan; submitted to the Dept. of Computer Science. Title from PDF t.p. (viewed Aug. 25, 2009). Includes bibliographical references (p. 65-67).