An analysis of the Viterbi decoder error statistics for ATM and TCP/IP over satellite communication

Convolutional encoding and Viterbi decoding are error correction techniques widely used to improve the bit error rate (BER) performance over satellite communications (SATCOM) systems. The error statistics generated with these techniques are not random, but instead bursty. In today´s communications infrastructure, SATCOM terminals are used to provide the range extension for tactical communication systems. These tactical communications systems employ either asynchronous transfer mode (ATM) switching and/or Internet protocol IP) technology. Both ATM and IP require high quality channels with BERs on the order of 10^-8 or better. Traditional SATCOM channels only provide BER performance on the order of 10^-5. Concatenated codes are one solution for improving the quality of SATCOM links. But the burstness of the Viterbi decoding limits the effectiveness of the concatenated codes. Performance can be improved by including an interleaver to disperse the Viterbi error bursts. We present the Viterbi decoder´s error burst statistics (i.e. burst size and the interarrival times) as a function of the signal to noise ratio. Given these statistics, the performance of two different tactical communications systems are assessed: (1) an ATM based switching system and (2) an IP based system