A contribution to the reduction of the dynamic power dissipation in the turbo decoder

In the field of mobile communication systems, the energy issue of a turbo decoder becomes an equivalent constraint as throughput and performance. This paper presents a contribution to the reduction of the power consumption in the turbo decoder. The main idea is based on re-encoding technique combined with dummy insertion during the iterative decoding process. This technique, named “toward zero path” (TZP) helps in reducing the state transition activity of the Max-Log-MAP algorithm by trying to maintain the survivor path on the ‘zero path’ of the trellis. The design of a turbo decoder based on the TZP technique, associated with different power reduction technique (saturation of state metrics, stoping criterium) is described. The resulting turbo decoder was implemented onto a Xilinx VirtexII-Pro field-programmable gate array (FPGA) in a digital communication experimental setup. Performance and accurate power dissipation measurements have been done thanks to dynamic partial reconfiguration of the FPGA device. The experimental results have shown the interest of the different contributions for the design of turbo decoders.