Cooperative Coded Partial Retransmission scheme using Type-I HARQ and LDPC codes

In this paper we present a novel Hybrid Automatic Repeat reQuest (HARQ) scheme for cooperative communication systems, called Coded Partial Retransmission (CPR). The method is based on the retransmission of only a fraction of the original codeword by the cooperating nodes, applying an appropriate power allocation. Numerical results using LDPC codes and Type-I HARQ with Chase Combining show that CPR outperforms regular cooperative HARQ techniques considering both amplify-and-forward (AAF) and selective decode-and-forward (SDF) protocols. Additionally, we show that the CPR throughput, using a single relay, may be considerably larger than the throughput of some regular cooperative HARQ schemes using multiple relays.