Design and analysis of high performance multicast time-multiplexed switches

Pao Yue-kong Library Electronic Theses Database

Design and analysis of high performance multicast time-multiplexed switches


Author: Chan, Man-chi
Title: Design and analysis of high performance multicast time-multiplexed switches
Degree: M.Phil.
Year: 1998
Subject: Telecommunication -- Traffic
Telecommunication -- Switching systems
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Electronic Engineering
Pages: x, 113 leaves : ill. ; 30 cm
Language: English
InnoPac Record:
Abstract: This thesis focuses on the time slot assignment (TSA) problems associated with multicast time multiplexed switches (TMS). It begins with a brief review of the problems and existing solutions. Based on the review, existing methods in solving these problems are systematically classified and organized according to their pros and cons. Having recognized the demand for more promising approach to tackle the TSA problems, especially, for the multicast mixed traffic, the project aims to study how a multicast TMS can he designed to overcome these problems. By understanding the nature of the problems and the shortcomings of the existing methods, an effective switching technique, namely, zone switching, is proposed as a hint for designing a high-performance multicast TMS. The idea of zone switching is to provide more rooms for call scheduling via a proper switch design. The switch using this technique in principle can eliminate most of call blocking inherently without the need of sophisticated control algorithm, which would limit the growth of switch in terms of size and speed. To implement this switching concept, two efficient switch architectures are developed for multicast TMS. The first design has a demux-mux architecture, which is a building block for cross-connect nodes in various broadband communication systems. By exploiting trunk grouping at both input and output ports, the demux-mux switch can remove most slot contentions and achieves better performance. The second one is a simple multistage switch. It is designed to implement a novel scheduling scheme, window scheduling, which is the simplest and an efficient way to implement zone switching. Since the multistage switch consists only of several switching planes and a set of delay elements, it is very suitable for using in an all-optical network (AON). Although zone switching has very outstanding performance, it does not work well when one or more involved lines are heavily loaded. Another efficient design technique, internal bandwidth expansion, is thus proposed. As illustrated from its name, this technique reduces the level of slot contention by increasing the internal bandwidth, which in turn provides more alternatives to connect a call request. Based on this concept, a time-space-time (TST) switch with intermediate line dilation is developed. This switch has internal bandwidth doubled and can eliminate almost all the slot contentions. However, the tradeoff may be the requirement of buffer stages at both input and output time slot interchangers (TSI). This greatly reduces the feasibility of implementing it in lightwave systems. Indeed, multicast TMS designed based on either one of these techniques can achieve substantial performance improvement. For cost-efficient design, it is suggested to use internal bandwidth expansion, if its implementation is feasible. Otherwise, zone switching is a good alternative to provide the same extent of improvement. Throughout this thesis, the switch performance is measured as the average call blocking probability and is evaluated via purely analytical means. The analytical results are each comparable to those predicted via computer simulations, which shows that the analytical models are valid for use.

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