Hybrid survivor path architectures for Viterbi decoders

A new approach to survivor path architectures for Viterbi decoders is proposed based on hybrid architectures that combine the classical register-exchange and trace-back methods. Two classes of hybrid architecture are proposed: the hybrid pretrace-back architecture and the hybrid trace-forward architecture. Pretrace-back is a preprocessing of the add-compare-select (ACS) decisions to increase the effective trace-back recursion rate, while trace-forward is a concurrent processing of the decisions to initialize the trace-back recursion. Both of these architectures can be implemented using a single compact memory, typically twice the survivor path length in size, without any loss in throughput compared with conventional trace-back architectures. Based on area estimates for common decoding problems the hybrid architectures reduce the required chip area by up to 40% compared with the popular k-pointed trace-back architecture.<>