A New Efficient Convolutional Decoder for GSM Communication Standard with Fuzzy Logic

In GSM communication, one of the aspects is the convolutional encoding of speech data , using a 16 state encoder. Since for every bit, additional v bits are transmitted, there is good scope for error detection and correction. Using state diagram at each time slot, Trellis diagrams are considered as good illustrations for the method of decoding the data and an algorithm by Viterbi is in vogue. Compared to that, the proposed technique is based on the assignment of probability values to the states at all bit timings using certain principles of fuzzy logic. By this, the length limitation of the earlier algorithm is overcome since the memory requirement is only to store the best probable fuzziness values at each time slot and hence faster and code efficient. Comparative illustrations for sample data are given. Further, the method yields the same result of the best possible data accuracy as with the trellis coding. The method has been exhaustively tested for its reliable decoding.