Performance analysis of OCDMA PON configuration supporting multi-rate bursty traffic with retrials and QoS differentiation

An Optical Code Division Multiple Access (OCDMA) Passive Optical Network (PON) is a highly promising PON configuration, thanks to the potential of OCDMA technology in eliminating channel contention and efficiently supporting multi-rate traffic with different QoS requirements. In this paper, we provide a mathematical framework for a call-level performance analysis of an OCDMA PON that accommodates multiple service-classes of bursty traffic with retries. Blocked calls of random arrivals may immediately retry several times, by requesting less resources (number of codewords) each time, in order to be admitted for service. The bursty nature of traffic is denoted by the fact that in-service calls may alternate between transmission and no-transmission periods. Our analysis takes into account user activity and the various components of additive noise. An approximate recursive formula is derived for the efficient calculation of call-level performance measures. The proposed analytical model is further extended to assess the performance of an OCDMA PON that provides QoS differentiation, through the utilization of multiple-weight optical codes. Both proposed models are verified through simulation and found to be absolutely satisfactory. Moreover, comparison of the new models with a model without retries shows the necessity and effectiveness of the new models.