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A multicode optical code-division multiplexing (OCDM) is proposed to support the dynamic changes in the requested traffic demand in OCDM networks by adapting the number of allocated codes according to the requested transmission rate. In order to support time-variant data rates and multiservice transmissions; a multicode variable-weight 2D one-coincidence frequency hopping code/optical orthogonal code (OCFHC/OOC) is employed as the signature code in the proposed system. Two multicode assignment methods, namely, random multicode assignment (RMA) policy and uniform multicode assignment (UMA) policy, are presented. For each code assignment method, we drive the probability density function (pdf) of the number of active codes in each wavelength group. The bit error probability (BEP), the probability of degradation, and the blocking probability are derived as network performance key parameters. The proposed system has a simplified routing and code assignment process with a lower blocking probability. Our numerical results indicate that the network teletraffic capacity and blocking probability can be improved significantly using UMA policy and call admission control. [ABSTRACT FROM PUBLISHER]

In this paper, an optical code-division multiple-access (OCDMA) system employing overlapping pulse-position modulation (OPPM) is proposed to support multimedia services with different bit-rate and quality-of-service (QoS) requirements in OCDMA networks. Both wrapped OPPM (WOPPM) and unwrapped OPPM (UOPPM) are considered. The proposed system achieves multirate and multi-QoS transmission by using multilength variable-weight optical orthogonal codes (MLVW-OOCs) as signature sequences and using different values of OPPM modulation parameters. Furthermore, numerical analysis is performed for two different receiver structures, namely, correlation receivers with and without hard-limiters. In our analysis, the multiple-access interference (MAI) is considered as the main performance limiting factor. In addition, the performance of the proposed system is evaluated and compared to that of traditional OOK-OCDMA system. Our results reveal that under both pulsewidth and throughput constraints, the performances of the proposed WOPPM- and UOPPM-OCDMA systems are significantly superior to that of OOK-OCDMA system. [ABSTRACT FROM PUBLISHER]