A PERFORMANCE STUDY OF FORWARD ERROR-CORRECTION IN ATM NETWORKS

The asynchronous transfer mode technique (ATM) has been standardized as the transport system for future broad band communication networks. ATM allows the multiplexing and transmission of data from different services over the same network. If the cell loss rate in the network is higher than the loss rate requested by the service, the protocols in die endsystems must make up for the difference in loss rate. Traditionally, a retransmission-based scheme (i.e. ARQ) is used to recover from loss of data. In high bandwidth delay-product networks the latency introduced by retransmission-based error recovery schemes may become unacceptably high. Forward error correction (FEC) schemes do not have this drawback. When FEC is used, the transmitter sends with the original data some redundant data that can be used by the receiver to reconstruct lost pieces of the original data without requesting their retransmission. FEC trades off an increase in the bandwidth required for the capability to recover from partial loss. We use simulation to study an FEC scheme that can recover a fixed number of lost cells within a block of consecutive cells. The results obtained for different traffic scenarios demonstrate that FEC can reduce the loss rate by multiple orders of magnitude. FEC is shown to be most effective when used by video sources in a heterogeneous traffic scenario consisting of video and burst sources.