Cross-Layer Link Adaptation Design for Relay Channels with Cooperative ARQ Protocol

摘要

The cooperative automatic repeat request (C-ARQ) is a link layer relayingprotocol which exploits the spatial diversity and allows the relay node toretransmit the source data packet to the destination, when the latter is unableto decode the source data correctly. This paper presents a cross-layer linkadaptation design for C-ARQ based relay channels in which both source and relaynodes employ adaptive modulation coding and power adaptation at the physicallayer. For this scenario, we first derive closed-form expressions for thesystem spectral efficiency and average power consumption. We then present a lowcomplexity iterative algorithm to find the optimized adaptation solution bymaximizing the spectral efficiency subject to a packet loss rate (PLR) and anaverage power consumption constraint. The results indicate that the proposedadaptation scheme enhances the spectral efficiency noticeably when compared toother adaptive schemes, while guaranteeing the required PLR performance.