Reducing power consumption of turbo code decoder using adaptive iteration with variable supply voltage

Turbo code becomes popular for the next generation wireless communication systems because of its remarkable coding performance. One of the problems for decoding turbo code in the receiver is the complexity and the high power consumption since multiple iterations of the Soft Output Viterbi Algorithm (SOVA) have to be carried out to decode a data frame. In this paper, we address the issues of reducing the complexity and power consumption of the turbo code decoder. An approach using cyclic redundancy checking (CRC) to adaptively terminate the SOVA iteration of each frame is presented. This results in system that has variable workload of which the amount of computation required for each data frame is different. Dynamic voltage scaling is then used to further reduce the power consumption. However, since the workload is not yet known at the time when the data is being decoded, optimum voltage assignment is not feasible. In this work, we propose two heuristic algorithms to assign supply voltage for different decoding iterations. Simulation results show that significant reduction of power consumption is achieved compared with a system using fixed supply voltage.