A novel method for performance improvement of optical CDMA system using alterable concatenated code

A novel method using alterable concatenated code to pre-encode is proposed to reduce the impact of system impairment and multiple access interference (MAI) in optical code division multiple access (OCDMA) system, comprehensive comparisons between different concatenated code type and forward error correcting (FEC) scheme are studied by simulation. In the scheme, we apply concatenated coding to the embedded modulation scheme, and optical orthogonal code (OOC) is employed as address sequence code, an avalanche photodiode (APD) is selected as the system receiver. The bit error rate (BER) performance is derived taking into account the effect of some noises, dispersion power penalty and the MAI. From both theoretical analysis and numerical results, we can show that the proposed system has good performance at a BER of 10−9 with a gain of 6.4 dB improvement achieved using the concatenated code as the pre-code, and this scheme permits implementation of a cost effective OCDMA system.