Implementation of A Low Power Modified Viterbi Decoder With T-Algorithm

We propose a pre-computation architecture incorporated with T-algorithm for VD, which can effectively reduce the power consumption without degrading the decoding speed much. A general solution to derive the optimal pre-computation steps is also given in the paper. The AddCompare Select (ACS) unit in path metric unit is designed to reduce the latency of ACS loop delay by using Modified Carry Look Ahead Adder and Digital Comparator. We also consider the design of Survivor Memory Unit (SMU) which combines the advantages of both Register Exchange method and Trace Back method, to reduce the decoding latency and total area of the Viterbi decoder. The proposed Viterbi decoder design is described using Verilog HDL Implementation result of a VD for a rate-3/4 convolutional code used in a TCM system shows that compared with the full trellis VD, the precomputation architecture reduces the power consumption by as much as 70% without performance loss, while the degradation in clock speed is negligible.