The invention of the telephone and the telegraph opened the door to worldwide corrmunications. Over the years, complex and versatile corrmunication systems have evolved involving many devices and technologies. Switching protocols between switching offices have been established in accordance with the nature of the machines and with the capabilities of the transmission medium and its environment. Switching systems are now stored program oriented, providing a more generalized and digitally oriented internal switching capability. This report will discuss the Time Slot Interchange ( TSI), an important component of the Digital Central Office (DCO). The operation of the send section and the receive section and their relationship to the port group highways and cross office highways are presented in detail. The various TSI corrmands for performing the necessary operations are discussed. The TSI considered is that designed by Stromberg-Carlson, and future design trends in the design are presented.

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

This thesis is devoted to the analysis of problems that arise when long products of matrices taken in a given set are constructed. A typical application is the stability of switched linear systems. The stability of a discrete-time linear system is a classical engineering problem that has been well understood for long: the dynamics can be expressed in terms of the eigenvalues of the matrix ruling the system. A more complicated problem arises when the dynamical system can switch, that is, if the matrix changes over time. If this matrix is taken from a given set but can be chosen arbitrarily in this set at every time, the stability problem turns to the computation of a quantity, the joint spectral radius of the set of matrices, introduced in the early sixties. While this quantity appears to be hard to compute, it has acquired more and more importance during the last decades, and new applications of the joint spectral radius in engineering or mathematics are frequently discovered. It has for instance been proved useful for the analysis of regularity of fractals, for the continuity of wavelets, or for autonomous agents detection in sensor networks. In the first part of this thesis, we present a theoretical survey of the joint spectral radius, including old and new results. The joint spectral subradius, which is its stabilizability counterpart, is also considered. In a second part, we study some applications related to long products of matrices. We first analyse in detail a problem in coding theory, that has been recently shown to involve a joint spectral radius computation. We then propose a new application of the joint spectral radius (and related quantities) to a classical problem in number theory, namely the counting of overlap-free words. We then turn to problems related with autonomous agents detection: we analyse the trackability of sensor networks, and introduce and analyse a new notion, namely the observability of sensor networks.

The focus of this dissertation is the development of resource management schemes for integrated networks, with the major contributions being: (i) the development of an optimal adaptive buffer management scheme for the packet-switched subsystem, (ii) the integration of a moveable-boundary hybrid switching scheme with the time assigned speech interpolation technique for implementing a congestion control mechanism for the packet-switched subsystem, and (iii) the development of an adaptive hierarchical scheme for implementing the access control and routing functions within the circuit-switched subsystem. The problem of buffer management at an integrated network node is formulated as a nonlinear programming problem with a convex objective function and an interative solution technique with fast convergence is proposed for a real-time implementation of the buffer management scheme in practical environments. In order to exercise an additional degree of control over the packet-blocking probability at each hybrid-switched link within the network, a new multiplexing scheme based on the integration of the moveable-boundary hybrid switching scheme and the time assigned speech interpolation technique is presented in this dissertation. The tradeoff between the corresponding decrease in the packet blocking probability and the increase in the circuit freezeout fraction is demonstrated by a detailed queueing analysis of the multiplexer. Specific algorithms are also presented in this dissertation for the solution of the access control and routing problems within the circuit-switched subsystem. In particular, an access control scheme is developed by solving an integer programming problem formulated using the policy of complete partitioning of the available bandwidth among the competing user classes. As an alternative to the completely partitioned approach, the problem of traffic routing is considered in a network that supports homogeneous traffic classes based on the policy of complete sharing. Finally, for the general case of networks with heterogeneous traffic classes, a hierarchical scheme is developed for the implementation of the access control and the routing functions at two functional levels, where the access control is implemented by the network supervisor who solves an appropriate linear integer programming problem periodically, and the routing function is handled by the individual nodes of the network on a distributed basis. (Abstract shortened with permission of author.)

Lam Wan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 139-145). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

An Zhuo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 62-65). / Abstracts in English and Chinese. / Acknowledgments --- p.i / 摘要 --- p.ii / Abstract --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Circuit switching and Packet switching --- p.2 / Chapter 1.2 --- Virtual paths in high-speed networks --- p.6 / Chapter 1.3 --- BEF in cross-path switch --- p.8 / Chapter 1.4 --- Organization --- p.11 / Chapter Chapter 2 --- Analysis models --- p.12 / Chapter 2.1 --- Routing schemes in Clos network --- p.12 / Chapter 2.2 --- Path Switching --- p.15 / Chapter 2.3 --- Traffic Model of Input Modules --- p.17 / Chapter 2.4 --- Traffic Model of Output Modules --- p.19 / Chapter 2.5 --- Summary --- p.23 / Chapter Chapter 3 --- Throughput Performance of Input Modules in Path Switching --- p.24 / Chapter 3.1 --- Throughput performance vs. BEF --- p.24 / Chapter 3.2 --- Throughput performance vs. number of virtual paths --- p.30 / Chapter 3.2.1 --- Throughput performance vs. integer group size m/k --- p.33 / Chapter 3.2.2 --- Throughput performance vs. group size 0<R<2 --- p.39 / Chapter 3.2.3 --- Throughput performance vs. look-ahead scheme window size ω --- p.46 / Chapter 3.3 --- Summary --- p.48 / Chapter Chapter 4 --- Traffic Balancing Control in Path Switching --- p.50 / Chapter 4.1 --- Loss Probability in Output Modules --- p.50 / Chapter 4.1.1 --- Loss probability vs. number of central modules m --- p.51 / Chapter 4.1.2 --- Loss probability vs. knockout group size R and cluster size g --- p.52 / Chapter 4.2 --- Simulation Comparison of look-ahead scheme --- p.53 / Chapter 4.3 --- Simulation result of throughput vs. BEF --- p.55 / Chapter 4.4 --- Traffic Balancing Control --- p.55 / Chapter 4.5 --- Summary --- p.53 / Chapter Chapter 5 --- Conclusion --- p.60 / Bibliography --- p.62

by Vincent Wing-Shing Tse. / Thesis submitted in: December 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 62-[64]). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Principles of Multirate Circuit Switching in Quantized Clos Network --- p.10 / Chapter 2.1 --- Formulation of Multirate Circuit Switching --- p.11 / Chapter 2.2 --- Call Level Routing in Quantized Clos Network --- p.12 / Chapter 2.3 --- Cell Level Routing in Quantized Clos Network --- p.16 / Chapter 2.3.1 --- Traffic Behavior in ATM Network --- p.17 / Chapter 2.3.2 --- Time Division Multiplexing in Multirate Circuit Switching and Cell-level Switching in ATM Network --- p.19 / Chapter 2.3.3 --- Cell Transmission Scheduling --- p.20 / Chapter 2.3.4 --- Capacity Allocation and Route Assignment at Cell-level --- p.29 / Chapter 3 --- Performance Evaluation of Different Implementation Schemes --- p.31 / Chapter 3.1 --- Global Control and Distributed Switching --- p.32 / Chapter 3.2 --- Implementation Schemes of Quantized Clos Network --- p.33 / Chapter 3.2.1 --- Classification of Switch Modules --- p.33 / Chapter 3.2.2 --- Bufferless Switch Modules Construction Scheme --- p.38 / Chapter 3.2.3 --- Buffered Switch Modules Construction Scheme --- p.42 / Chapter 3.3 --- Complexity Comparison --- p.44 / Chapter 3.4 --- Delay Performance of The Two Implementation Schemes --- p.47 / Chapter 3.4.1 --- Assumption --- p.47 / Chapter 3.4.2 --- Simulation Result --- p.50 / Chapter 4 --- Conclusions --- p.59 / Bibliography --- p.62

Microfiche copy available in the Institute Archives and Barker Engineering Library. / Vita. / Thesis (Ph. D.)--Massachusetts Institute of Technology. Dept. of Engineering and Computer Science, 1977. / Includes bibliographical references. / by John Ippocratis Capetanakis. / Ph.D.

A method is proposed to infer stability properties for non-linear switching under continuous state feedback. Continuous-time systems which are dissipative in the multiple storage function sense are considered. A partition of the state space, induced by the cross-supply rates and the feedback function, is used to derive a restriction on switching. Then, conditions are proposed, under which, systems controlled by the feedback function and switching according to the rule are stable. In particular, Lyapunov and asymptotic stability are proved, both in a local and in a global context. Further, it is shown that the approach can be extended when one uses multiple controllers, and, therefore, is able to construct multiple partitions; conditions for this case are also presented. Finally, it is shown that, for the switching families that satisfy the switching rule posited by the results, one is able to find elements (that is, stabilising switching laws for the system) which are non-Zeno. Additional rule-sets that allow this are provided. It is argued that the conditions proposed here are easier to verify and apply, and that they offer additional flexibility when compared to those proposed by other approaches in the literature. The same infrastructure is used in the study of hybrid systems. For a general class of non-linear hybrid systems, a new property is proposed, that retains some of the properties of dissipativity, but it differs from it, crucially in the fact that it is not purely input-output. For systems having this property, it is shown that the partition used in the switching case can also be used. This, along with a set of conditions allows for the characterisation of the system behaviour in two scenaria. First, when the continuous behaviours and the jumping scheme act co-operatively, leading the system to lower energy levels (from the dissipativity point of view). Second, when the continuous behaviours are allowed to increase the stored energy, but the jumping is able to 6 compensate this increase. In the first case, it is shown that the equilibrium point under study is stable; in the second, it is shown that the system exhibits a type of attractivity, and, under additional conditions, it is asymptotically stable. Besides stability, a collection of stabilisation results are given for the case of dissipative switching systems. It is shown that one may design state feedback functions (controllers) with the objective that they satisfy the conditions of the stability theorems in this work. Then, systems under the designed controllers are shown to be stable, provided that the switching adheres to a specific switching rule. This problem is approached using a variety of tools taken from analysis, multi-valued functions and the space of non-switching stabilisation. In addition to the main results, an extensive overview of the literature in the area of switching and hybrid systems is offered, with emphasis on the topics of stability and dissipativity. Finally, a collection of numerical examples are given, validating the results presented here.

by Chan Man Chi. / "June 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 150-[160]). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.