ARQ Protocols for High Efficiency Digital Communication Systems

Abstract

Automatic repeat request (ARQ) techniques are largely used in digital satellite communication systems for their high reliability and simple implementation. The main disadvantage of the ARQ techniques is their low throughput, particularly at mean and high error rates. In this paper a class of ARQ schemes, termed ARQ protocols with memory, is described. In these protocols the received vectors, even those detected as erroneous, are retained and used in the successive transmissions of the same message to facilitate their correct recovery. The introduction of this memory at the receiver permits to enhance the performance of an ARQ scheme. In this way, the region of the signal-to-noise ratios, in which the ARQ protocols can be applied, is significantly extended and the performance of the ARQ techniques can achieve acceptable values also for high error rates.

Indexing terms:

• Atomatic repeat request protocols
• Digital communication systems
• Channel coding