Adaptive-rate code combining for wireless infrared communications systems employing direction diversity

Infrared radiation may be used as an alternative to radio for short-range indoor wireless local area networks. Communication using infrared radiation is particularly suitable for military applications as the signal cannot pass through walls. In this paper, we evaluate the performance of an infrared link composed of a multi-beam transmitter and a direction-diversity receiver, employing code combining. Rate-compatible punctured convolutional (RCPC) codes are used to provide an adaptive environment for efficient utilization of channel spectral bandwidth, and to maintain a guaranteed bit-error rate (BER) performance at all receiver positions. It is shown that a BER not exceeding 10^-9 with 99% probability can be achieved at bit rates up to a few hundreds of Mbps, at low transmitted power levels.