A share-controlled PFQ algorithm is proposed for IntServ EPON. It divides packet scheduling into high-priority phase and low-priority phase. In the high-priority phase, an improved PFQ algorithm is presented, which introduces a new constraint and a control factor into the scheduling discipline to overcome bandwidth preemption and to freely distribute excess bandwidth. Computer simulation results show that both the reserved services and non-reserved service can obtain excellent QoS performance when scheduled with the proposed algorithm.
In the downstream direction of EPON, all ethernet frames share one downlink channel from the OLT to destination ONUs. To guarantee differentiated services, a scheduling algorithm is needed to solve the link-sharing issue. In this paper, we first review the classical WFQ algorithm and point out the shortcomings existing in the fair queueing principle of WFQ algorithm for EPON. Then we propose a novel scheduling algorithm called Priority-based WFQ (PWFQ) algorithm which distributes bandwidth based on priority. PWFQ algorithm can guarantee the quality of real-time services whether under light load or under heavy load. Simulation results also show that PWFQ algorithm not only can improve delay performance of real-time services, but can also meet the worst-case delay bound requirements.