Mobile MC-CDMA optical wireless system employing an adaptive multibeam transmitter and diversity receivers in a real indoor environment

Multicarrier Code Division Multiple Access (MC-CDMA) combines some of the desirable feature of Orthogonal Frequency Division Multiplexing (OFDM) and CDMA in that it offers multiple access facilities at a reduced channel rate. In this paper, the channel characteristics of mobile infrared links have been modelled in a highly impaired environment in the presence of windows, office cubicles, bookshelves, and shadowing. We introduce an adaptive line strip multibeam system (ALSMS) in conjunction with diversity detection and show that it dramatically improves the SNR performance of infrared links in the presence of very directive noise and shadowing. Our results indicate that, the mobile MC-CDMA ALSMS system with an angle diversity receiver offers a significant performance improvement including a reduction in the background noise (BN) effect, a strong received power, reduction in delay spread, and improvement in the SNR over the mobile MC-CDMA LSMS system in the poor communication environment considered. Furthermore, the OW MC-CDMA system operates at a channel rate lower than that associated with OW CDMA systems and we demonstrate the performance improvement obtained in a real OW environment in the presence of transmitter and receiver mobility.