Design of variable wordlength Viterbi decoder in BICM-OFDM systems

This paper presents a new design method for reducing power dissipation of Viterbi decoder using variable wordlength architectures in wireless bit-interleaved coded modulation and orthogonal frequency division multiplexing (BICMOFDM) systems. The proposed method observes wireless communication quality and adjusts a wordlength in order to keep a desirable PER. Two types of the Viterbi decoder are used for this evaluation. When we use the variable wordlength instead of 8-bit fixed wordlength, the radix-2 Viterbi decoder reduce its power by maximums of 26.3% and 24% under multipath fading environments, respectively. The radix-4 Viterbi decoder reduced its power by maximums of 31.6% and 28.8% under the same conditions.