Multirate asynchronous optical CDMA system with product code

The authors propose a new architecture for a multirate asynchronous optical CDMA (code division multiple access) system. An optical orthogonal code (OOC) is employed as the signature sequence. The serial multirate data is converted into parallel information bits and then transmitted simultaneously via spatial channels. Exploiting the essence of parallel transmission of spatial channels, the product code (i.e. rectangular code) through an extra protection channel performs error control, which can significantly improve the system performance. The authors' proposed scheme requires only one laser diode, sequence encoder and product-coded encoder/decoder. Moreover, the adverse impact of multiple access interference, APD (avalanche photodiode) noise and thermal noise are taken into consideration in system performance analysis.