Effect of non-reciprocity on infrared wireless local-area networks

Summary form only given. The advanced infrared (AIr) is a wireless infrared (IR) network standard proposed to the Infrared Data Association. The AIr provides a dynamic tradeoff between bit rate and transmission range by using four-slot pulse-position modulation with variable-rate repetition coding. At the media-access control (MAC) layer, the AIr uses carrier-sensing multiple access/collision avoidance (CSMA/CA) with exchange of request-to-send and clear-to-send (RTS/CTS) packets to prevent collisions in the case of hidden terminals. Reliable operation of RTS/CTS exchange requires reciprocity, i.e. the signal-to-noise ratio must be symmetric between each pair of transceivers. We investigate the impact of non-reciprocity on the performance of IR wireless LANs, focusing on the example of AIr networks. The study uses a hierarchical simulation methodology. The first step is to specify the physical characteristics of a set of transceivers (e.g. the directionalities of transmitting and receiving elements) and of the room in which they operate (e.g. ambient light levels). A physical-layer simulator computes the signal, interference and noise powers in each receiver. Theoretical error probability expressions are used to compute the probability of successful packet transmission. Finally, discrete-event Monte Carlo simulation of the AIr MAC protocol is used to quantify the network performance. The results indicate that non-reciprocity can substantially reduce throughput and increase unfairness