Congestion Control in a Wireless ATM Network over a Markovian Channel

In this work, as a congestion control, the selective celt discarding scheme with an adaptive type-I hybrid automatic repeat request (ARQ) protocol in a wireless ATM network over a Markovian channel is modelled by a fluid queue. In our model, the traffic source is composed of two mini ON-OFF sources of high and low priority cell generators as a layered coded variable bit rate (VBR) source. For cell discarding scheme, when the buffer content exceeds a threshold, the incoming low priority cells are discarded. With an adaptive type-I hybrid ARQ protocol, different error correcting capability is introduced according to each state of the radio channel for combating the fluctuation of channel error statistics. Performance is measured in terms of loss behavior of high and low priority cells, which consists of the controlled loss produced by cell discarding and the tail loss produced at the end of the buffer. Such loss performance of adaptive type-I hybrid ARQ protocol is compared to non-adaptive one according to the source and channel correlation, the threshold, the discarding rate and error correction capability