Uplink Transmission Scheme based on Rateless Coding in Cloud RAN

This paper considers single user uplink transmission based on rateless coding in Cloud Radio Access Network(C-RAN). The system consists of one user, multiple remote radio head(RRH) and a baseband unit(BBU) pool. The user encodes the messages with rateless code which are then modulated and sent. Each RRH which covers the user quantizes the received signals and transfers them to the BBU pool through the high rate link. The BBU pool applies belief propagation(BP) algorithm for joint decompression and decoding for the received quantized signals from all the RRHs. In order to further improve the system performance, we resort to the extrinsic mutual information transfer(EXIT) analysis to optimize the degree profile of the rateless code implemented by the user. The simulation results show that the rateless code with optimized degree profile achieves a lower bit error ratio(BER) as well as a higher throughput, compared with the optimal degree profile under the binary erasure channel (BEC). Moreover, the performance of the optimized profile approaches the theoretical limit of the system.