Study and simulation of cell queuing time delay in optical access network system

Cell access time delay of ONU (Optical Network Unit, ONU) in BPON (Broadband Passive Optical Network based on ATM) is studied and emulated in this paper. An algorithm of upstream cell time delay and cache length or buffer size in the ONU are given, which is based on the queuing theory of M/G/l/infinity model. Through simulation experiment by using OPNET, CD(Cell Delay) and CDV (Cell Delay Variation) results of CBR and VBR cell streams are acquired. The experimental results show that by using queuing theory of M/G/1/infinity, CD and CDV can be reduced and capability of access network can be improved, which would provide higher QoS. The given algorithm in this paper can improve capabilities of Cell Delay and Cell Delay Variation, provide the referenced theory criterion of BPON MAC (Media Access Control) protocol designing.