Optimality of chip-level detection for OCDMA

This paper derives the optimal chip error rate (CER) of the chip-level detection for optical code division multiple-access communication (OCDMA). By introducing two auxiliary functions and exploring their properties, it is shown for the first time that when the detection is based on the photon counts, the optimal CER can be achieved uniquely by thresholding the receiving photon counts at each chip with a threshold of one. Simulation studies verify the theoretical analysis.