Minimizing mean packet delay in EPONs through Integrated Grant Scheduling

In Ethernet Passive Optical Networks (EPONs) with offline Dynamic Bandwidth Allocation (DBA) framework, the Optical Line Terminal (OLT) will first collect bandwidth requests from all Optical Network Units (ONUs), and then make bandwidth allocation and scheduling decisions for the shared upstream channel. Due to varying Round-Trip Time (RTT) and grant window sizes, the transmission order of ONUs will greatly affect the mean packet delay. In this paper, we address this grant scheduling problem aiming at minimizing the mean packet delay. We prove several theorems which could determine the ONU to transmit first which will minimize the mean packet delay. And then, by iteratively using these theorems, we propose an Integrated Grant Scheduling (IGS) algorithm to determine the optimal transmission order to minimize the mean packet delay. We then conduct simulations to evaluate the performance of our algorithm, and find that the performance of our algorithm is better compared with other algorithms under various conditions.