Performance enhancement of asynchronous overlapping PPM-OCDMA systems using projected PIC multiuser detection

Overlapping pulse position modulation-optical code division multiple access (OPPM-OCDMA) is a well known technique to enhance spectral efficiency and to increase the number of effective users in the system. However, on the other hand overlapping may result in increasing levels of multiple access interference (MAI) that significantly reduces the capacity of the system. To mitigate MAI, we make use of a recently proposed parallel interference cancellation (PIC) technique that exploits the non-negativity of the incoherent direct detection OPPM-OCDMA system to boost its performance. Simulation results reveal a considerable increase in the spectral efficiency of the system.