Slotted ALOHA in High Speed Bidirectional Bus Networks

The speed of a bus network is often specified by the Abstract parameter a, which denotes the end-to-end propagation delay normalized with respect to the We study the performance of the slotted ALOIH A average packet transmission time. With current multiple access protocol in a high speed bidirectional technology and cost trends, typical values of a in most passive bus network, where transmissions are in the isting bus networks range between zero and one. form of packets of constant length. Slotted ALOHA Advances in the technology of optical generally considered to have better throughp i communications and the inc reasing demand for generallyfcornsdere to have better throughput performance than unslottcd ALOHA, whose maximum transmissions of relatively short packets promise throughput is known to be 1/(2e), independent of future bidirectional bus networks with normalized station configuration. We show that, with a end-to-end propagation delay exceeding one. station configuration. We show that, with a probabilistic station configuration, the throughput of ~slotted ALOHA ~ can de~rade~ to 1 The fundamental limits of random access protocols slotted ALOHA can degrade to 1/(3e) when the end-to-end propagation delay is significantly larger than the have been widely studied [61. It is common knoledge packet transmission time. Nevertheless, in some very that in many contention-based multiple access packet transmission time. Nevertheless, in some ver p high speed bidirectional bus networks with a protocols with carrier sensing, throughput deterministic station configuration, the throughput performance degrades with a because the overhead of slotted ALOHA can be as high as 1/2. for monitoring channel activities increases with a [7]. In our analysis of the slotted ALOHA protocol, we assume that there is no carrier sensing. Manv random access strategies for unidirectional bus networks operating at high speeds have been studied 1