A LDPC-based IR scheme for cooperative relay system

A cooperative IR (Incremental Redundancy) scheme in a three-node relay system is studied in this paper. The soft encoding at the relay is adopted to avoid the error propagation and improve the transmission efficiency. Alamouti coding is considered at the source and the relay to get cooperative transmitting diversity. We also derive the optimal IR LDPC codes by linear optimization of the whole code under Gaussian Approximation. At last, we simulate the proposed scheme under Rayleigh channel, the results show that the proposed scheme significantly outperforms the traditional IR strategy without the relay.