NEW PPM-CDMA HYBRID FOR INDOOR DIFFUSE INFRARED CHANNELS

An original hybrid pulse position modulation code division multiple access (PPM-CDMA) communication technique that uses optical orthogonal codes (OOCs) is proposed and studied in the context of the indoor infrared channel. At the optimum PPM order and over the range of parameters considered, the hybrid is shown to achieve more than five times the bit rate achievable using conventional on on keying (OOK) CDMA under bandwidth constraints. Original results are presented for the false alarm errors due to the OOC crosscorrelations, and the optimum system operating parameters that minimise these errors are specified.