Opportunistic Fair Scheduling for the Downlink of 802.16WirelessMetropolitan Area Networks
Mehri Mehrjoo, Mehrdad Dianati, Xuemin (Sherman) Shen,
and Kshirasagar Naik
Department of Electrical and Computer EngineeringUniversity of Waterloo, Ontario, Canada
The Third International Conference on Quality of Service inHeterogeneous Wired/Wireless Networks(QShine’06)
Introduction_802.16(1)
Defines two transmission mode Point-to-MultiPoint (PMP) mode Mesh mode
PMP mode is designed for high rate transmission service with support
of various QoS Require all SSs to be with clear LOS
Introduction_802.16(2)
Four service flows have been defined : Unsolicited Grant Service (UGS) Real-time Polling Service (rtPS) Non-real-time Polling Service (nrtPS) Best Effort (BE) service
Opportunistic Fair Scheduling Scheme_motive
an optimal scheduling policy is to transmit to SSs with the best channel quality at the maximum achievable rates in each scheduling interval and cause unfairness
a fairness mechanism is deployed to assign bandwidth to each SS according to its history of transmission and average channel quality
Opportunistic Fair Scheduling Scheme_(1)
Assume that can achieve a transmission rate of Shannon’s upperbound and there are N nodes
average power gain of the
channel
allocated power to SSjRj is the allocated rate to SSj
The total power budget
of the BS
Opportunistic Fair Scheduling Scheme_(3)utility function
is the weighted minimum average rate
is the weighted maximum average rate
is the weighted rate
is the rate allocation vector
Rj is the allocated rate to SSj
Opportunistic Fair Scheduling Scheme_(4)the fair of scheduling
Fair share weight, denoted by ( ) as follows:
Approximately utility fair allocation :
Simulation_(4)Gini fairness index
If I=0 ,mean perfect fairness
and are the long term average transmissionrate and the fair share weight of SSk