A semi-classical analysis of optical code division multiple access

The exact error rate has been derived for the noncoherent, optical matched-filter CDMA receiver, which decides for the data of a single user by comparing a photoelectron count to a threshold. The analysis is valid for arbitrary quantum efficiencies, binary signature sequences, random gain distributions, and dark currents, and it is broad in application. Single-user demodulation based on a conditionally compound-Poisson observation has been considered, focusing on the special case of prime codes, equal energies, and utility-gain photodetectors. It has been found that the approximation of perfect optical-to-electrical conversion yields poor estimates of the error rate and optimal threshold at moderate incident optical intensities and dark currents. Further, the combined approximation of perfect optical-to-electrical conversion and Gaussian-distributed MAI yields an underestimate of the optimal threshold and an error rate that is neither an upper nor a lower bound.<>