Slotted ALOHA in high speed bidirectional bus networks

The performance of the slotted ALOHA multiple access protocol in a high-speed bidirectional passive bus network, where transmissions are in the form of packets of constant length, is studied. Slotted ALOHA is generally considered to have better throughput performance than unslotted ALOHA, whose maximum throughput is known to be 1/(2e), independent of station configuration. It is shown that, with a probabilistic station configuration, the throughput of slotted ALOHA can degrade to 1/(3e) when the end-to-end propagation delay is significantly larger than the packet transmission time. Nevertheless, in some very high speed bidirectional bus networks with a deterministic station configuration, the throughput of slotted ALOHA can be as high as 1/2