Dynamic bandwidth allocation (DBA) is a key issue of Ethernet PONs. In order to get higher resource utilization and lower packet delay, the problem is always dissolved into grant sizing and grant scheduling. In this paper, we explore grant scheduling techniques. We propose a modified hybrid online and offline scheduling with the shortest propagation delay (SPD) first policy (we named HSPD) which can compensate for the idle time under light or medium loaded traffic. Meanwhile, the last ONU in

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... line set is adaptively indicated to transmit REPORT frame first (called LRF), so the idle time can be eliminated especially under heavy loaded traffic. We evaluate the cycle length and average packet delay through analysis and simulations. Compared with the offline SPD first scheduling (we named it OSPD), and online and offline scheduling with excess bandwidth distribution (so-called M-DBA1), we find out our algorithm HSPD-LRF can achieve significant improvements in terms of average packet delay and channel utilization.