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Admission Control and Interference-Aware Scheduling in Mult

i-hop WiMAX Networks

Debalina Ghosh, Ashima Gupta, Prasant Mohapatra

Department of Computer ScienceUniversity of California, Davis

IEEE MASS 2007

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Outline

Introduction Network Model Scheduling Algorithm Simulation Conclusion

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Introduction_ WiMAX topology

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Introduction_ Service Classes in WiMAX

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Introduction_ Goal

BS

UGS:Max rateLatency nrtPS

rtPS :Max rateMin rateLatency

2. admit more flows

3. Maximum bandwidth utilization

1. QoS guarantee

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Network Model_ Assumption

BS1. Routing from a source to a destination is fixed and non-adaptive2. The flows are non-splittable

3. All nodes are half-duplex

4. All links use the same coding scheme across all frames5. Physical layer is Orthogonal frequency division multiple access (OFDMA)

6. Link rate is the same

7. Link is even-odd labeling

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Scheduling Algorithm_ (1)

Scheduling Algorithm ScheduleFlowSubchannel (SFS) Timeslot-1 Timeslot-2

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Scheduling Algorithm_ (1)

Max bandwidth = 5 slots

Min bandwidth = 3 slots

Max bandwidth =10 slots

Min bandwidth = 4 slots

BS

Run scheduling Algorithm

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Scheduling Algorithm_ start slot

BS

deadlinestartFrame start

20020 20100 20

(200-100-20*3) / 10 =2 slot

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Scheduling Algorithm_ ScheduleFlowSubchannel(SFS)

BS

slot

subchannel

Maxslots = 10

Frame start Free slot Allocated slot

slotsalloc = 0slotsalloc = 2slotsalloc = 4

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Scheduling Algorithm_ Timeslot-1

BS

slot

subchannel

Maxslots = 10

Frame start Free slot Allocated slot

slotsalloc = 0slotsalloc = 1slotsalloc = 2

V

V

V

V

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Scheduling Algorithm_ Timeslot-2

BS

slot

subchannel

Maxslots = 10

Frame start Free slot Allocated slot

slotsalloc = 0slotsalloc = 0slotsalloc = 1slotsalloc = 1

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Scheduling Algorithm_ Naïve Algorithm

BS

slot

subchannel

Minslots = 3

Frame start Free slot Allocated slot

slotsalloc = 0slotsalloc = 1slotsalloc = 2slotsalloc =3

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Simulation_ parameter(1)

Frame size is 5ms The maximum number of Subchannel

are 256 Simulator written in C

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Simulation_ schedule efficiency (SE) metric

Admitted flows

Total flows

weight total bandwidth(minrate) allocated to UG

S flows

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Conclusion

The authors describe five algorithm Each of the algorithms guarantee collision

free schedules by scheduling only non-interfering links in the same slots

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Thank you~