High-speed FPGA Implementation Of Turbo Codes Based Cooperative Communication System

Due to its excellent performance, turbo codes have been widely used in recentyears. Meanwhile, the system throughput can be effectively improved in a multipleaccess relay channel while combining the diversity technology and the network codingtechnology. Therefore, the adoption of turbo coding and network coding in acooperative communication system, not only can provide reliable transmission, but alsocan increase network forwarding efficiency and system throughput. This paper hasconducted an in-depth theoretical study on the turbo codes based joint network-channelcoding cooperative communication system, and implemented this system on FPGA.The channel coding theory and the relay transmission technology have beenoutlined firstly, followed a discussion of the applications of turbo codes in cooperativecommunication systems. In the multiple access relay channel, the turbo codes basedjoint network-channel coding transmission scheme has been given. In this scheme, therelay encodes the joint network-channel codes with the estimation of the two mobilestations’ information bits, and then forwards it to the base station. The base stationperforms iterative decoding over physical layer and network layer, resulting in a furtherimprovement of the system decoding performance.Then by introducing the concept of a high-radix trellis graphs, combining thedesign idea of exchanging area for speed, and changing the structure of the ACS circuit,an algorithm suitable for hardware implementation is proposed. This algorithm shortensthe critical path, and eventually enhances the decoder’s throughput without affecting itserror correction capacity.Finally, after multi-layered quantization and sliding window of the decoder, thehigh speed FPGA implementation of the turbo codes based joint network-channelcoding cooperative communication system has been given, whose throughput can reachabout21Mbps.