Improved design and analysis of diversity optical-wireless CDMA

A diversity incoherent optical-wireless code-division multiple-access (OW-CDMA) scheme was recently proposed, in which each simultaneous user transmits multiple (time-shifted) copies of its optical code per data bit of one in order to achieve good performance. The analysis was performed under the ideal “copy-independent” assumption for ease of mathematical treatment. However, complete copy-independency is hard to achieve, especially when short-length optical codes are used, because there are not enough time-slots for the copies to be positioned. In this paper, we combine the effects of copy-dependency and “timeslot granularity” in the analysis of our diversity OW-CDMA scheme and formulate a new, generalized, and more accurate performance model with validation by computer simulation.