A New Hybrid ARQ-FEC Scheme For Wireless ATM Networks

Abstract

Wired ATM (Asynchronous Transfer Mode) networks are designed taking into account an optical link in the physical layer. The main problem to implement a wireless ATM network is the fact that its radio link bit error rate is high and variable, demanding the use of an additional error control mechanism. The usual techniques for error control are ARQ (Automatic Repeat Request) and FEC (Forward Error Correction). ARQ works better than FEC if the channel bit error rate is low, and is worse if it is high, thus indicating that hybrid ARQ-FEC techniques can improve the radio link performance. A new hybrid ARQ-FEC scheme with multiple FEC states is proposed in this paper. The performance of the proposed scheme is compared with non-adaptive ARQ and FEC schemes, which have similar complexities, and with an ideal adaptive FEC scheme. It is shown that the proposed scheme works better than the non-adaptive schemes, and that the hybrid and the ideal adaptive FEC schemes have similar performances. Moreover, the hybrid scheme does not require an estimate of the bit error rate in the channel, leading to a less complex implementation.