Optimized Relay Selection Strategy for Adaptive Network Coded Cooperation

Adaptive network coded cooperation (ANCC) scheme has been shown to have better performance than the conventional repetition-based schemes and the space-time coded cooperation (STCC) frameworks for data transmissions from a large collection of terminals to a common destination in large wireless networks. However, the random selection strategy for ANCC protocol may generate many short cycles in the distributed low-density generator-matrix(LDGM) codes, which may cause error-floor and performance degradation. In this paper, an optimized relay selection strategy for ANCC is proposed. By exploiting information interaction between destination and terminals before data communication, and matching the instantaneous network topology, the proposed method generates ensembles of distributed LDGM codes free of short cycles. Simulation results demonstrate that the proposed relay selection protocol significantly outperforms the random relay selection strategy for various network sizes and different fixed numbers of selected terminals.