Performance enhancement of 2-D OCDMA systems using multi-code modulation and heterodyne detection

A new modulation scheme for 2-D OCDMA systems named multi-code modulation (MCM) is proposed in this paper. The key advantage of MCM over the conventional ones is the ability of mitigating simultaneously both multiple access interference and dispersion. We also propose to combine MCM with heterodyne detection, a powerful technique to relax optical beating interference, to obtain better performance. The numerical results show that the proposed system allows for lower bit error rate, lower required power, and higher user's bit rate than that of conventional ones using other modulation schemes such as on-off keying modulation, pulse amplitude modulation, and pulse position modulation.