Multiplexed ARQ for time-varying channels. I. System model and throughput analysis

In this paper, a model is developed for a slotted time-division multiplexing system used for assigning transmissions over a set of time-varying channels. Two schemes, a "round-robin" and an adaptive multiplexing scheme, are studied for use with three standard automatic-repeat-request (ARQ) protocols, namely, stop-and-wait (SW), go-back-N (GBN), and ideal selective repeat (ISR). In round-robin multiplexing, transmission slots are assigned periodically to each channel, With the adaptive scheme, the multiplexer selects at each time slot the channel whose state is estimated to have the lowest retransmission probability. The throughputs of these ARQ protocols under either multiplexing scheme are analyzed and compared. The present paper contains a description of the system model and an analysis of the ARQ protocols under both multiplexing schemes. In Part II, a modification to GBN and selective repeat ARQ for reducing the detrimental effects of feedback errors is discussed and analyzed, followed by a throughput performance comparison of all ARQ and multiplexing schemes.