## Abstract

Online scheduling algorithms incur no idle time problem but with less bandwidth
efficiency, while offline scheduling algorithms focus on bandwidth efficiency
but with idle time overhead. Although a just-in-time (JIT) scheduling algorithm
for multi-channel Ethernet passive optical networks (EPONs) has been proposed to
increase the bandwidth efficiency without the idle time overhead, its
applicability to single-channel EPONs is problematic. A new algorithm called
fitting scheduling timing–elastic weighted granting (FST–EWG) is
proposed and is suitable for single-channel EPONs. First, the FST determines the
fitting timing for performing the dynamic bandwidth allocation scheduling
algorithm in an attempt to consider as many optical network unit (ONU) demands
as possible and to avoid the unnecessary idle time as much as possible. Then the
EWG can efficiently re-allocate the excess bandwidth of light-load ONUs to all
heavy-load ONUs. The computation complexity of the proposed FST–EWG is
linear and is denoted as $O\left(N\right)$, where *N* is the number of
ONUs. Simulation results show that FST–EWG efficiently allocates
bandwidth compared to previously proposed algorithms in terms of average packet
delay and packet dropping probability, especially for higher load. In addition,
by adding the non-strict priority intra-ONU scheduling, FST–EWG also
outperforms the previously proposed DBAM method in terms of EF average delay and
EF delay variation.

© 2012 OSA

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