OPTICAL ORTHOGONAL CODE-DIVISION MULTIPLE-ACCESS SYSTEM .1. APD NOISE AND THERMAL NOISE

In an optical multiple-access system, overall system throughput efficiency and significant implementation cost-reduction would be achieved if many users could access a common optical channel at any time without control among users. Recently one such scheme, an optical orthogonal code division multiple-access system (OOCDMA), was introduced by Salehi et al. [1]-[61 for the case of no noise. In this paper, some extensions of the work in [21 are presented, including the effects of avalanche photodiode (APD) noise and thermal noise as well as interference for the OOCDMA direct-detection receiver. Since it has been shown [2], [3] that an optical hard-limiter before the receiver correlator can reduce the interference effect for the OOCDMA system in the absence of noise, the hard-limiter role in the presence of thermal and APD noise is also examined.