The Impact of Channel Feedback on Opportunistic Relay Selection for Hybrid-ARQ in Wireless Networks


Caleb K. Lo, Robert W. Heath, Jr., and Sriram Vishwanath


IEEE Transactions on Vehicular Technology, vol. 58, no. 3, pp. 1255-1268, March 2009.


This paper presents a decentralized relay selection protocol in a dense wireless network and describes channel feedback strategies that improve its performance. The proposed selection protocol supports hybrid automatic-repeat-request transmission where relays forward parity information to the destination in the event of a decoding error. Channel feedback is employed for refining the relay selection process and for selecting an appropriate transmission mode in an adaptive modulation setup. An approximation of the throughput of the proposed adaptive modulation strategy is presented, and the dependence of the throughput on system parameters such as the relay feedback probability and the adaptive modulation switching point is illustrated via optimization of this approximation. Simulations show that the throughput of the proposed selection strategy is comparable to that yielded by a centralized selection approach that relies on geographic information.