We study the use of multiuser detection and blind detection techniques to improve the performance of optical code division multiple access (OCDMA) systems. First, a new multiuser receiver known as the interference suppression receiver is proposed. Second, we study the use of blind detection by proposing a blind receiver for OCDMA systems. While previous studies on multiuser detection are limited to systems with p-i-n detectors, avalanche photodiode detectors are also included here.

In the analysis of the bit-error rate (BER) of an optical communication system with avalanche photodiode (APD) detectors, the Webb, McIntyre, Conradi (1974) distribution has been often used to approximate the APD receiver output statistics. This paper presents new simple and closed form BER expressions as well as an importance sampling technique for optical systems employing APD receivers when the WMC model is used. Comparison of the WMC model with the exact model is also carried out. In particular, it is shown that the WMC distribution is quite accurate and has the advantage of simplicity for both simulation and analysis.

Recently, there has been a lot of interest in using code-division multiple access (CDMA) for optical fiber communication systems. In this letter, we present a technique for estimating the bit error rate of optical CDMA communication systems employing avalanche photodiode receivers. The proposed technique, which is based on large deviations theory, is featured as a simple, accurate, and flexible method for performance evaluation of such systems.

Optical code division multiple access has been proposed as an alternative multiple access scheme for multiuser fiber-optic communication systems. Many previous works on the receivers for such systems have focused on the correlation receiver which is optimal in the single user case. However, it has been shown that the performance of the correlation receiver is unsatisfactory when there is a large number of interferers. Multiuser detection becomes an appealing method to improve the system performance. In this paper, a new multiuser detector for optical code division multiple access communication systems, referred to as the multistage decorrelating receiver, is proposed. Its structure is much simpler than the optimal multiuser detector at the expense of slight performance degradation. Both simulation and analysis of the receiver are carried out. Comparison of the proposed detector with several other receivers is also presented.