Infrared wireless communication using spread spectrum techniques

The performance of nondirected line-of-sight indoor wireless infrared commu nication systems is mainly affected by ambient light-induced shot noise, mu ltipath dispersion and interference produced by artificial light sources. A pplication of spread spectrum techniques to combat multipath dispersion and artificial light interference is presented, with bit error rate analysis c onsidering these two effects. Experiments were carried out to verify the bi t error rate analysis and to demonstrate the practical performance of a spr ead spectrum system. For the line-of-sight link investigated, both experime ntal and analytical results show that a spread spectrum system operating at 2 Mbit/s and with spreading factor 31 suffers a power penalty of less than 0.5 optical dB due to multipath dispersion, and less than one optical dB p enalty is incurred under the influence of 10 dB artificial light interferen ce.