Repeated convolutional codes for high error rate channel

An error correction scheme for an M-ary symmetric channel (MSC) characterized by a large error probability (p_e) is considered. The value of p_e can be near, but smaller than, 1-1/M for which the channel capacity is zero. Such a large p_e may occur, for example, in a jamming environment. The coding scheme considered consists of an outer convolutional code and an inner repetition code of length m which is used for each convolutional code symbol. At the receiving end, the m inner code symbols are used to form a soft-decision metric which is subsequently passed to a soft-decision decoder for the convolutional code. Emphasis is placed on using a binary convolutional code. Effect of finite quantization and methods to generate binary metric for M>2 are investigated. For the binary symmetric channel a bit error rate (BER) approximation method is proposed for large m based on the central limit theorem. The influence of various decoding metrics is investigated