Transformation of ACS module to CSA module of low-power Viterbi decoder for digital wireless communication applications

This paper presents a low-power CSA (Comparator-Selector-Adder) module of the Viterbi decoder alternative of standard synchronous ACS (Adder-Comparator-Selector) module to reduce the high power consumption. A simple full adder is used for Hamming distance calculation for branch metric selection to reduce complex circuitry elements and saving power dissipation. The power dissipation can be reduced by first comparison method where selection might be faster than ACS module. If first comparison fails then it takes second comparison for decision-making. These improvements upgrade the module for working at more power saving environment, and also save the performance degradation in conventional ACS design. The experimental result claims that the design proposal has a power consumption reduced by 10% (approximate) over the conventional ACS design and also applicable for Selective update, Shift update and Register exchange approach.