1. 1 Admission Control and Interference-Aware Scheduling in Multi-hop WiMAX Networks Debalina Ghosh, Ashima Gupta, Prasant Mohapatra Department of Computer ScienceUniversity of California, Davis IEEE MASS 2007

2. 2 Outline  Introduction  Network Model  Scheduling Algorithm  Simulation  Conclusion

3. 3 Introduction_ WiMAX topology

4. 4 Introduction_ Service Classes in WiMAX

5. 5 Introduction_ Goal BS UGS: Max rate Latency nrtPS rtPS : Max rate Min rate Latency 2. admit more flows 3. Maximum bandwidth utilization 1. QoS guarantee

6. 6 Network Model_ Assumption BS 1. Routing from a source to a destination is fixed and non-adaptive 2. The flows are non-splittable 3. All nodes are half-duplex 4. All links use the same coding scheme across all frames 5. Physical layer is Orthogonal frequency division multiple access (OFDMA) 6. Link rate is the same 7. Link is even-odd labeling

7. 7 Scheduling Algorithm_ (1)  Scheduling Algorithm ScheduleFlowSubchannel (SFS) Timeslot-1 Timeslot-2

8. 8 Scheduling Algorithm_ (1) Max bandwidth = 5 slots Min bandwidth = 3 slots Max bandwidth =10 slots Min bandwidth = 4 slots BS Run scheduling Algorithm

9. 9 Scheduling Algorithm_ start slot BS deadline start Frame start 200 20 100 20 (200-100-20*3) / 10 =2 slot

10. 10 Scheduling Algorithm_ ScheduleFlowSubchannel( SFS) BS slot subchannel Maxslots = 10 Frame start Free slotAllocated slot slotsalloc = 0slotsalloc = 2slotsalloc = 4

11. 11 Scheduling Algorithm_ Timeslot-1 BS slot subchannel Maxslots = 10 Frame start Free slotAllocated slot slotsalloc = 0slotsalloc = 1slotsalloc = 2 V V V V

12. 12 Scheduling Algorithm_ Timeslot-2 BS slot subchannel Maxslots = 10 Frame start Free slotAllocated slot slotsalloc = 0 slotsalloc = 1

13. 13 Scheduling Algorithm_ Naïve Algorithm BS slot subchannel Minslots = 3 Frame start Free slotAllocated slot slotsalloc = 0 slotsalloc = 1 slotsalloc = 2 slotsalloc =3

14. 14 Simulation_ parameter(1)  Frame size is 5ms  The maximum number of Subchannel are 256  Simulator written in C

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16. 16 Simulation_ schedule efficiency (SE) metric Admitted flows Total flows weight total bandwidth (minrate) allocated to UGS flows

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20. 20 Conclusion  The authors describe five algorithm  Each of the algorithms guarantee collision free schedules by scheduling only non- interfering links in the same slots

21. 21 Thank you~