An Enhanced EDD QoS Scheduler for IEEE 802.11e WLAN - Advances in Computational Science and Engineering - page 58

Fig. 10. Average delay in scenario 2 (VBR trac)
Fig. 11. Jitter in scenario 2 (VBR trac)
5Conluon
Since the existing scheduling algorithms for IEEE 802.11e do not reflect well
the characteristics of the trac, it causes increase of mean delay, jitter and
packet loss ratio especially when bursty VBR trac is applied. In this paper, we
proposed a new scheduling algorithm to improve the performance of HCCA. The
proposed scheduler guarantees QoS by changing suitably service intervals and
transmission opportunities. The service schedule is based not only on the TSPEC
parameters of a flow but also on the trac queueing. Simulation results show
that the proposed scheduling algorithm is superior to the reference scheduler
and SETT-EDD scheduler in terms of throughput, end-to-end delay and jitter.
Simulation results showed that our scheduler outperformed the reference and
SETT-EDD schedulers In this paper, our scheduling algorithm operated under
assumption of a stable channel. However, The future circumstance of wireless
network co-exists with various wireless technologies. More ecient scheduling
study should be done under the circumstance of an unstable wireless channel.