Study of a Diversity O-CDMA Scheme for Optical Wireless

Borrowing from wireless communications, a “diversity” optical code-division multiple-access (O-CDMA) scheme for optical wireless is studied in this paper. The scheme transmits multiple copies of an optical code per data bit of one for improving code performance and spectral efficiency. An approximate performance-analytical model is also formulated for quick computation and comparison with a conventional O-CDMA scheme. Under the assumptions of same code power and hardware complexity, our study finds an important application of the diversity scheme, which circumvents a heavy code-weight requirement (for achieving good code performance) in conventional O-CDMA by transmitting multiple copies of lower weight codes with little penalty in spectral efficiency and without depletion in code cardinality (i.e., the number of possible subscribers.)