The throughput of hybrid-ARQ protocols for the Gaussian collision channel

TLDR

Next‑generation wireless systems will add packet‑oriented data transmission to standard mobile telephony. The study investigates the throughput and average delay of hybrid‑ARQ protocols over a slotted Gaussian multiple‑access channel with fading, and examines their asymptotic behavior with respect to system parameters. Using the renewal‑reward theorem, the authors derive closed‑form throughput expressions for these protocols. The results show that hybrid‑ARQ throughput rivals that of CDMA with conventional decoding and that ARQ systems are not interference‑limited even without multiuser detection, unlike CDMA.

Abstract

In next-generation wireless communication systems, packet-oriented data transmission will be implemented in addition to standard mobile telephony. We take an information-theoretic view of some simple protocols for reliable packet communication based on "hybrid-ARQ," over a slotted multiple-access Gaussian channel with fading and study their throughput (total bit per second per hertz) and average delay under idealized but fairly general assumptions. As an application of the renewal-reward theorem, we obtain closed-form throughput formulas. Then, we consider asymptotic behaviors with respect to various system parameters. The throughput of automatic retransmission request (ARQ) protocols is compared to that of code division multiple access (CDMA) with conventional decoding. Interestingly, the ARQ systems are not interference-limited even if no multiuser detection or joint decoding is used, as opposed to conventional CDMA.