Frequency-time controlled (FTC) networks for high speed communication

Abstract

The development of “very high speed” networks is being motivated by emerging applications and is therefore attracting increasing attention. As demonstrated in the past, in conventional high speed systems the high ratio between the end-to-end propagation delay and the message transmission time severely restricts the system performance. Thus the increase in channel bandwidth may be accompanied by only a marginal increase in actual system capacity. In this paper we propose a network architecture which eliminates this problem by introducing a combined Frequency - Time Division based control of the high speed channel. We consider the implementation characteristics of the resulting multichannel system and show that the design of protocols in these systems is subject to unique channel control penalties. Specifically, we show that in addition to the relatively high cost of channel sensing, the allocation of channel on a demand assignment basis is hindered in the multichannel configuration by the time penalty involved in locating an idle channel and by practical limitations of multichannel node interface design. 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 message source and destination oriented transmission rights allocation, taking into account the implementation aspects 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 a uniform analytic treatment. The analysis demonstrates the potential for a significant improvement in the system capacity and the average message delay, when compared to a conventional single (undivided) channel system.