Performance Analysis of One stage and Two stage Parallel Interference Cancellation for Optical Code Division Multiple Access System

Code division multiple access (CDMA) is a powerful multiplexing scheme which is very suited to the optical domain with its broad spectrum. Optical code division multiple access (OCDMA) technique allows multiple users to share the same transmission media by assigning different codes and is a very promising technique for the broadband communication. OCDMA networks can provide all customers with upstream data rates of Gigabits/seconds with inherent flexibility. In the optical domain, the traditional method to recover the data at the receiving end of an optical CDMA system is to use an optical correlator followed by a photo detector and a decision device. However as the number of simultaneous users increases the capacity of the system is limited by Multiple Access Interference (MAI) and various detection noises. There are many reception techniques like decorrelation receiver, Minimum Mean Square error, Interference Cancellation etc. which are very efficient for multiuser detection in Radio frequency (RF) communication .Their success in RF domain has inspired usage in OCDMA. Interference Cancellation techniques are any technique or combination of techniques that allow an existing receiver to operate with higher levels of co-channel interference. This paper presents the effect of MAI, using parallel interference cancellation (PIC) techniques for incoherent OCDMA which is non-linear multiuser detector. One stage and two stage PIC, have been simulated for various data rates and fiber lengths. Simulated results show that two stage PIC shows better performance than Direct detection technique and one stage PIC. Keywords— BER, CDMA, DD, MAI, OCDMA, PIC