Successive Interference Cancellation for DS-Optical PPM-CDMA Systems

In this paper we introduce a successive interference cancellation (SIC) scheme for direct sequence optical code division multiple access (DS-OCDMA) systems using pulse position modulation (PPM). Considering double-padded modified prime code (DPMPC) as a signature sequence code, results show that the system has better performance in terms of both capacity and bit error rate (BER) as compared to the one without cancellation scheme, where the system with SIC scheme can support up to 88 users while the system without SIC scheme can support only 38 users at similar BER=10−9. Although the receiver sensitivity is affected by the overlapping between users, which limits the system performance, the theoretical analysis of this issue indicates the influence of the size of M-ary PPM on OCDMA system. Hence, the BER value is still sufficient for good system performance