Effects of analogue ACS implementation errors on the modified feedback decoding algorithm

Convolutional decoders have long been important in applications where very noisy channels are encountered. The most commonly employed convolutional decoding technique is the Viterbi algorithm (VA). This provides an optimum method for realising a convolutional decoder, but requires a large amount of digital path memory. Recently, the modified feedback decoding algorithm (MFDA) has been suggested as a new alternative approach to the VA. The MFDA requires no digital path memory and so can be realised using mainly analogue components. This paper investigates the effects on the coding performance of the MFDA when its add-compare-select (ACS) block is realised using analogue circuit techniques.