Asynchronous multirate optical wireless PPM-CDMA in an indoor non-directed diffuse channel

Asynchronous multirate pulse position modulation-code division multiple access (PPM-CDMA) is proposed for an indoor optical wireless time dispersive channel. As a signature sequence for CDMA, an optical orthogonal code (OOC) is used. The optical PPM-CDMA has advantages in that it is power efficient and provides multirate services by simply varying the modulation level for the fixed chip rate at the transmitter and sampling time at the receiver