Performance of rateless codes in half-duplex collaborative relay networks

Cooperative communications, where parallel relays forward information to a destination node, can greatly improve the energy efficiency and latency in ad-hoc networks. Communications using rateless codes, in which the source transmits an infinite number of parity bits to the destination until the receipt of an acknowledgement, provides a natural and efficient mechanism for accumulating information from multiple transmitting relays. One decode-and-forward protocol and one amplify-and-forward protocol both based on rateless codes are studied in this paper. The impact of the half-duplex constraint on the throughput of the system using rateless codes to harness spatial diversity and efficiently transmit information from a source to a destination is analyzed in our paper. Specially, the direct path from source to destination in a free-space path loss and small-scale Rayleigh environment is considered, which is often ignored in many other papers. Simulations show that the decode-and-forward protocol works more efficiently than the amplify-and-forward protocol.