Comparison of different error control schemes for wireless ATM

In wireless ATM systems, the introduction of an error control scheme at the air interface is mandatory in order to meet the constraints on the cell loss rate. Error control must be able to cope with the characteristics of the radio channel which is usually a channel with memory characterized by burst of errors, commonly modeled as a Gilbert-Elliott channel. Common approaches to the problem include standard forward error correction (FEC) techniques with bit interleaving implemented at the physical layer, and ARQ (automatic repeat request) techniques implemented at the MAC/DLC layer for non real-time applications only. However, the peculiar characteristics of the Gilbert-Elliott channel, for an extended range of channel parameters, are better exploited by other approaches. In this paper, we consider a wireless ATM access interface based on a TDMA scheme and real-time services with stringent delay constraints. The efficiencies of three error control schemes are compared: the classical FEC plus bit interleaving, a scheme based on block erasure codes, and a real-time ARQ scheme proposed in a previous paper. It turns out that the delay constraints can severely limit the performance of the FEC with respect to the other approaches