Distributed Analog Channel Coding for Wireless Relay Networks

Distributed coding has been shown to be an efficient scheme to improve the performance of wireless relay networks. In this paper we propose an analog distributed channel coding (ADC) scheme. In the proposed scheme, the intermediate relays directly process the received analog noisy signals without making the hard estimation and performs analog channel encoding of the noisy soft estimates of the transmitted symbols, so that the processed signals forwarded by all relays can form an analog distributed convolutional codeword. Assuming the source packet is encoded by a channel code, the ADC scheme can form serial concatenated codes and iterative decoding can be applied at the destination. We compare our proposed scheme with other existing schemes under Additive White Gaussian Noise (AWGN) and fast Rayleigh fading channel and validate the simulation results with the aid of Extrinsic Information Transfer (EXIT) chart analysis. Simulation results show that the proposed ADC scheme can effectively overcome the error propagation due to the erroneous decoding at the relay in the conventional decode-forward (DF) scheme and provide considerable coding gains, thus considerably outperforming the conventional soft information relaying protocols. The coding gains increase as the number of state in the relay encoder increases.