FEC schemes for ATM traffic over wireless links

ATM traffic carried over fiber optic links experiences low bit error rates (BER). For this reason, cell error/loss recovery techniques for ATM networks have thus far concentrated on cell losses due to congestion and buffer overflow at network switches. In this paper we analyze a different network scenario, namely ATM networks where the end-to-end link includes wireless media. The BER of these media may be significantly higher than that which only has optical fiber links. In addition, errors will occur in bursts and thus with high probability will overwhelm the error correcting capability of the header error control (HEC) in the ATM header. Due to the high bandwidth-delay product of the channel, pure ARQ schemes for cell error/loss recovery would be inefficient. Thus an FEC or hybrid FEC/ARQ scheme is needed to achieve acceptable cell loss rate for a given application. We analyze a concatenated FEC scheme with byte-level interleaving with a RS outer code and a convolutional inner code, and study its performance in AWGN and on a Rayleigh fading channel. We also present the throughput and delay (due to retransmission) performance of a hybrid FEC/ARQ scheme over the same channel model. The authors discuss satellite and mobile radio links as examples.