On the performance of Hybrid-PON scheduling strategies for NG-EPON

To effectively schedule transmissions in NG-EPON, Hybrid-PON is further classified into MSD-PON, SSD-PON, and WA-PON depending on their different access architectures, viz. how a group of ONUs share the assigned wavelength channels. The architectures for these three Hybrid-PONs were introduced by the IEEE 802.3 Ethernet Working Group in 2015. In this study, we first propose to apply some existing dynamic bandwidth allocation (DBA) schemes in the cases of MSD-PON and SSD-PON. Then, since WA-PON is a new hybrid multiplexing architecture and previous DBA schemes cannot exploit its flexibility of wavelength assignment and sharing, we develop the optimization model and also provide a novel DBA scheme for WA-PON. Then, we compare the performance of these hybrid PONs by simulation in terms of average delay and packet drop ratio. We analyze the influence of increasing buffer size for each ONU in WA-PON and show how the flexibility of WA-PON can impact the performance. We find that WA-PON can reduce the drop ratio compared with SSD-PON at low offered load, and has smaller average delay than MSD-PON, which suggest that WA-PON can tolerate heavier traffic and performs the best among three Hybrid-PON architectures.