Link Layer Protocols for Short-Range IR Communications

Abstract

The Infrared Data Association (IrDA) has standardized the widely used IrDA 1.x protocol stack for low-cost, indoor, short-range, point-to-point connectivity. The early adoption of IrDA and the widespread installation of millions of IrDA infrared ports in mobile devices for wireless communication applications necessitates for throughput performance optimization of the IR links at the link layer. The lessons learnt from the IrDA standard adoption issues should be a guide for future 5G device to device developments and other personal Infrared devices and applications, when it comes to the introduction of optical wireless and protocols into products. This chapter provides a review of a mathematical model, based on which we derive simple equations linking the link layer throughput with physical and link layer parameters. Simple equations for optimum values of window and frame size lengths for maximum link layer throughput as a function of BER are derived, and a study of the importance of parameters such as link minimum turnaround time and timeout timer is presented. Finally, a protocol improvement that utilizes special Supervisory frames (S-frames) to pass transmission control is proposed to deal with delays introduced by F-timer expiration. Results indicate that employing the special S-frame highly improves throughput performance when optimum window and frame size values are implemented.