Forward delay protection of time-critical traffic in ATM networks with FEC

Forward error correction (FEC) has been proposed for packet networks as an end-to-end method to protect against packet loss due to, for example, buffer overflows. The performance of FEC schemes has been investigated thoroughly in a number of studies, particularly in the context of ATM networks. The present author observes that if FEC is used in an ATM network environment for loss protection, then it may also be used simultaneously to reduce the probability that a cell is delayed excessively due to prevailing traffic conditions. This additional feature can be useful in time-critical applications, such as real-time data delivery, packet video, or synchronized multimedia object presentations, where there are time-deadlines to be met. Cells that fail to arrive at an end-system by the required deadline are treated as “virtual” erasures and reconstructed using FEC as if they had been lost. The effectiveness of FEC in reconstructing late cells is evaluated by simulating an ATM cell multiplexer with input streams consisting of variable bit rate packet video, fixed rate packet video, and background time-insensitive bursty data traffic. The FEC mechanism is found to be useful in reducing delay jitter and the probability of late cell arrival. It is also found to be useful in the combined purpose of reducing late cells and lost cells