POWER CONSUMPTION REDUCTION IN A VITERBI DECODER FOR OFDM-WLAN

WLAN standards make use of different transmission modes to cope with different channel conditions, these modes make use of different modulation constellations and code rates. Data encoding is done with a 64-state convolutional code of rate 1/2, some modes employ this basic rate and others puncture the encoded data to obtain a rate of 3/4. At the receiver, the decision depth needed by the Viterbi decoder is higher for decoding punctured modes than for decoding non-punctured modes, this means that punctured modes need a greater area and, then, they cause a higher power consumption. This fact is used in this letter to reduce the power consumption of the Viterbi decoder when dealing with half-rate code modes, an architecture that disables the unnecessary hardware in the non-punctured modes allows a reduction of 20% in the dynamic power consumption with an area increase of only 1%.