Performance study of BCJR decoding based hybrid ARQ for autonomous wireless bans

In this paper, a type-I hybrid automatic-repeat-request (ARQ) scheme based on the (15,10) shortened Hamming code with the Bahl, Cocke, Jelinek, and Raviv (BCJR) decoding algorithm is studied to suppress the transmit energy of bio-sensors in wireless body area networks (WBANs) by minimizing retransmission rate. The bit-error-rate is used as a reliability-based criterion to realize a flexible block-level retransmission. The superiority of the proposed scheme is explored by analyzing the BCJR decoding with both hard and soft inputs. It is shown that the retransmission rate of our reported scheme can be largely reduced in comparison with the retransmission scheme based on the syndrome decoding over not only AWGN channels but also practical WBAN fading channels corresponding to different transceiver positions and body movements. It is revealed that the transmit power of -5dBm is sufficient for the worst channel. This is especially useful for achieving autonomous WBANs where the sensors have strict energy budgets while the gateway has a more relaxed budget.