Use of FEC coding for real-time transport on ATM networks

The use of forward error-control (FEC) coding has emerged as a promising approach for real-time transport over ATM networks for cell-loss recovery. The use of an FEC-based transport protocol over networks with bandwidth constraints, however, is not obvious since FEC coding introduces an overhead which can possibly cause additional cell losses which, furthermore, tend to occur in bursts. In this work, an overall performance evaluation of FEC coding is provided by incorporating the effects of channel coding on the cell-loss characteristics of the network. It is shown that FEC coding with proper selection of channel coding rate can significantly improve the throughput at a multiplexer even under correlated cell-loss situations. We also develop and illustrate an information-theoretic approach for incorporating the effects of FEC coding into well-established queueing theory calculations. This is achieved by solving separately the channel-coding problem for the modeled transmission channel and the queueing problem for the network. The performance of some specific coding designs are shown to approach the information-theoretic predictions with increasing complexity and/or delay.