IrDA infrared wireless communications: protocol throughput optimization

Abstract

The delivery of the maximum data rate to users from IrDA IR wireless links depends not only on the physical layer, but also on higher-layer protocols being optimized. This article reviews the IrDA link layer protocol, IrLAP, and examines how to maximize its throughput performance. Simple equations yield to simple rules for the optimization of IrLAP. The analysis presented can also be employed in studying the physical layer requirements of the predicted future data rate increases (40 Mb/s and 100 Mb/s) of the IrDA 1.x standard. The model gives insights for the optimum control of the infrared connection for high performance. Simple formulas are derived for the optimum values of the window and frame size link layer parameters that maximize throughput. Results show that, for the proposed 16 Mb/s extension, significant throughput increase is observed if optimum link layer parameter values are employed. At high error rates, the significance of the minimum turnaround time (a physical layer parameter) and of the transmission control passing mechanism is studied. When the links are adapted to using the optimum window and frame size, combined with low minimum turnaround values and an efficient transmission control passing scheme, we observe performance improvements even at high error rates.