Throughput analysis of two multiplexing schemes for ARQ protocols in time-varying channels

A model is developed for a slotted time division multiplexing system used to assign transmissions over a set of time-varying channels. Two multiplexing schemes, a round-robin and an adaptive multiplexing scheme, are studied for three standard automatic-repeat-request (ARQ) protocols (stop-and-wait, go-back-N, and ideal selective repeat). With the adaptive scheme, the multiplexer selects, at each time slot, the channel whose state has the lowest retransmission probability. It is shown that the adaptive scheme can have a significantly higher throughput for go-back-N and selective repeat ARQ, whereas round-robin multiplexing tends to perform better than the adaptive scheme for stop-and-wait ARQ.