Design and evaluation of an adaptive data link control protocol for wireless ATM networks

This paper describes the design of an adaptive data link control (DLC) protocol for wireless ATM networks and measures its performance in a locally deployed testbed implemented by the RDRN (Rapidly Deployable Radio Network) project. Our DLC protocol provides quality of service (QoS) support for ATM-based virtual connections by distinguishing between delay-sensitive and loss-sensitive traffic over the wireless portion of the network. Delay sensitive traffic that is received with errors is dropped while loss-sensitive traffic that is lost or received with errors is selectively retransmitted using a go-back-N ARQ scheme. To overcome the unreliability of a wireless link, the DLC protocol exploits adaptation techniques that utilize channel state information to maximize the performance of individual connections. Our experiments shows that the adaptive data link control protocol under consideration is more robust at dealing with lossy wireless links than its non-adaptive counterpart version; we have achieved TCP/IP throughput speedups of up to 4 times in our adaptive protocol implementation for virtual connections established over both delay-sensitive and loss-sensitive channels across impaired wireless links.