Transmission characteristics of optical CDMA for local area networks

Optical code division multiple access (OCDMA) has been extensively studied for the evaluation of system performance. In the phase modulated OCDMA system, the coherent balance detector receiver was used with the phase-locked loop (PLL) for code and carrier phase synchronization. Due to the implementation limitations of phase coded OCDMA and the inefficiencies for noncoherent detection, this paper considers the homodyne correlation receiver using dual balance detector for the estimation of transmission performance. A general model applicable to any number of users is set up, including noises such as shot noise and equivalent receiver circuit noise in the receiver model as well as multiuser interference. Moreover, the code correlation properties are observed for the chosen prime code. The influence of the code phase alignment condition in its synchronizing process on system performance is also analyzed. Rather than concentrating the study on the strategy for the code synchronization procedure followed by the computation of the average acquisition time as the performance of interest, the probabilities of false alarm and bit error depending on the state of code phase alignment are on focus.