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Service Class Downlink Scheduling in WiMAX. Joseph Thaliath, Mabel Mary Joy, Elizabeth Priya John and Debabrata Das IEEE Communication Systems Software and Middleware and Workshops, 2008. COMSWARE. Outline. Introduction Service Class Downlink Scheduling (SCDS) Analytical Model For SCDS
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Service Class Downlink Scheduling in WiMAX Joseph Thaliath, Mabel Mary Joy, Elizabeth Priya John and Debabrata Das IEEE Communication Systems Software and Middleware and Workshops, 2008. COMSWARE
Outline • Introduction • Service Class Downlink Scheduling (SCDS) • Analytical Model For SCDS • Simulation • Conclusion
Introduction • IEEE 802.16a/d/e WiMAX operates in two modes: Point–to–Multi Point (PMP) and mesh modes • The BS traffic is expected to be very high during DL compared to UL • An effective downlink scheduling scheme for BS is essential to avoid the delays for real time traffic
Analytical Model For SCDS(1/5) • To estimate the arrival pattern (arrival rate), cumulative mean arrival rate (CMAR) of packets fori service in k station for the current downlink frame j is presented as • NPik is the number of packets for i service in k station • FT is the frame time
Analytical Model For SCDS(2/5) The number of packets estimated to arrive in the current frame NEik is calculated as NEik=CMARik*FT The metric for each service in a station is given Sik= NEik
Analytical Model For SCDS(3/5) • Rik is the weighted priority for i service in k station
Analytical Model For SCDS(4/5) • Mk is the metric for kth station which is calculated as sum of the weighted priorities of services within the station of the respective service queue • The weight or priority for each station can be calculated as
Analytical Model For SCDS(5/5) • Ns is the number of slots available in downlink frame • The number of slots Tk for a station within a downlink frame is given as Tk= floor (Wk* Ns) • Tik is the time slot for i service in k station, and Rik is the weighted priority for each service within that station Tik= floor (Rik*Tk)
Conclusion • By SCDS the reduction in delay and enhancement in QoS for real time traffic • Future work includes combination of SCDS with channel quality for enhancement of QoS and throughput