An analysis of convolutional coding for land mobile channels

The performance of convolutional coding is analyzed with reference to a land mobile radio channel. A two-state channel model is developed to determine the performance as a function of the probability of occurrence and duration of the fades. Using computer simulation, the relationship that exists between the Doppler frequency, the amount of diversity, the interleaving depth, and the bit error rate is shown. Coding is shown to provide a significant gain if the fades are relatively short. Using a feedback channel, an adaptive coding strategy uses punctured and repeated convolutional codes to achieve a variable-rate coding scheme. This adaptive coding strategy yields an appreciable coding gain even when long fades are present