Technical Report CS0414

Title: Frequency-Time Controlled Multichannel Networks for High-Speed Communication
Authors: I. Chlamtac and O. Ganz
Abstract: The development of "very high speed" networks is being motivated by emerging applications and is therefore attracting increasing attention. However, as demonstrated in the past, in conventional broadcast based nigh speed systems the high ratio between the end-to-end propagation delay and the message transmission time severely restricts the system performance so that the increase in channel bandwidth may be accompanied by only a marginal increase in the actual system capacity. In this paper we present a network design which eliminates this problem by using a Frequency Divided: Time Division controlled multichannel architecture. We consider the implementation characteristics of the proposed system and show that the design of protocols in these systems is subject to channel control penalties unique to this multichannel architecture. Specifically, we show that in addition to the relatively high cost of channel sensing, the allocation of channel on a demand assignment basis in a multichannel configuration is hindered by the most of locating an idle channel and by multichannel communication interface designs. We therefore introduce a new class of "allocation" protocols in which the channel access is obtained without the aforementioned penalties. The allocation protocols build on source and destination oriented transmission rights allocation, dictated by implementation consideralions of multichannel networks. We show that the class of "multichannel allocation" protocols covers the whole range of random access to fixed channel access control policies and introduce an analytic approach for their uniform analytic treatment. The analysis demonstrates the potential for a significant impovement in the system capacity and the average message delay, when compared to a conventional single (undivided) channel system. Lastly, we show that the maximum improvement is obtained by an optimal subdivision of the high speed network bandwidth given as a function of the chosen protocol and system configuration.
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