Butterfly and Benes-Based on-Chip Communication Networks for Multiprocessor Turbo Decoding

Several research activities have recently emerged aiming to propose multiprocessor implementations in order to achieve flexible and high throughput parallel iterative decoding. Besides application algorithm optimizations and application-specific instruction-set processor design, the on-chip communication network constitutes a major issue in this application domain. In this paper, the authors propose to use multistage interconnection networks as on-chip communication networks for parallel turbo decoding. Adapted benes and butterfly networks are proposed with detailed hardware implementation of network interfaces, routers, and topologies. In addition, appropriate packet format and routing for interleaved/deinterleaved extrinsic information exchanges are proposed. The flexibility of these on-chip communication networks enables their use for all turbo code standards and constitutes a promising feature for their reuse for any similar interleaved/deinterleaved iterative communication profile