1. Chia-Yu Yu 1, Sherali Zeadally 2, Naveen Chilamkurti 3, Ce-Kuen Shieh 1 1 Institute of Computer Communication Engineering and Department of Electrical Engineering, National Cheng Kung University, Taiwan 2 Department of Computer Science and Information Technology University of the District of Columbia, Washington 3 Dept. of Computer Science and Computer Engineering, La Trobe University, Melbourne, Australia International Conference On Mobile Technology, Applications, And Systems, (ACM Mobility Conference )2008

2. Outline  Introduction  Background  Related works  Proposed adaptive deficit priority queue (ADPQ) scheme  Simulation  Conclusion

3. Introduction  IEEE 802.11 (disadvantages)  Low transmission rates  Short transmission distances  IEEE 802.16 (advantages)  High speed access to internet  Broad coverage range  QoS support  Fast deployment and low costs

4. Introduction  Some papers [4] [5] proposed scheduling schemes to achieve the following two goals  That all service classes must meet their QoS requirements  The scheduling schemes must achieve efficiency and fairness among all service classes [4] Pahalawatta, P.; Berry, R.; Pappas, T.; Katsaggelos, A. “Content-Aware Resource Allocation and Packet Scheduling for Video Transmission over Wireless Networks,” IEEE Journal on Selected Areas in Communications, Volume 25, Issue 4, Page(s):749 – 759, May 2007. [5] Lera, A.; Molinaro, A.; Pizzi, S. “Channel-Aware Scheduling for QoS and Fairness Provisioning in IEEE 802.16/WiMAX Broadband Wireless Access Systems,” IEEE Network, Volume 21, Issue 5, Page(s):34 – 41, Sept.-Oct. 2007.

5. Introduction  To achieve these goals, related scheduling schemes have been proposed  Deficit Fair Priority Queue (DFPQ) [7]  Preemptive Deficit Fair Priority Queue (PDFPQ) [8] [7] Jianfeng Chen, Wenhua Jiao, Hongxi Wang, “A Service Flow Management Strategy for IEEE 802.16 Broadband Wireless Access Systems in TDD Mode,” ICC 2005, Page(s): 3422-3426, 16-20 May 2005. [8] Safa, Haidar; Artail, Hassan; Karam, Marcel; Soudah, Rawan; Khayat, Samar; “New Scheduling Architecture for IEEE 802.16 Wireless Metropolitan Area Network,” IEEE/ACS International Conference on Computer Systems and Applications, 2007, Page(s): 203-210, 13-16 May 2007.

6. Introduction  To propose an enhanced scheduling scheme called Adaptive Deficit Priority Queue (ADPQ)  To guarantee the delay of rtPS  To protect lower priority service classes from starvation

7. Background  Point-to-Multipoint network topology

8. Background  Point-to-Multipoint network topology  Downlink BSSS DL-MAP

9. Background  Point-to-Multipoint network topology  Uplink BSSS UL-MAP

10. Background  IEEE 802.16 standard defines four kinds of service classes  Unsolicited Grant Service (UGS)  Real-Time Polling Service (rtPS)  Non-Real-Time Polling Service (nrtPS)  Best Effort Service (BE)  The standard does not recommend any particular scheme in detail

11. Background  Unsolicited Grant Service (UGS)  Voice over IP (VoIP) Resource Time

12. Background  Real-Time Polling Service (rtPS)  Video streaming Resource Time

13. Background  Non-Real-Time Polling Service (nrtPS)  guarantees the minimum bandwidth and the longest delay tolerance range. nrtPS also uses polling to request bandwidth, but nrtPS is polled using a longer polling interval than rtPS  FTP  Best Effort Service (BE)  no QoS requirements  contention-based bandwidth request  HTTP

14. Related works  QoS architectures

15. Related works  Deficit Fair Priority Queue (DFPQ)  Definition ： Deficit Counter (DC) DC[rtPS] DC[nrtPS] DC[BE] 800 500 300

16. Related works  Deficit Fair Priority Queue (DFPQ) Classifier rtPSnrtPSBE 400 300 100 300 250 500 100 350 200 250 DC[rtPS] 800 DC[nrtPS] 500 DC[BE] 300 Scheduler

17. Related works  Deficit Fair Priority Queue (DFPQ) Classifier rtPSnrtPSBE 400 300 100 300 250 500 100 350 200 250 DC[rtPS] 800 DC[nrtPS] 500 DC[BE] 300 Scheduler DC[rtPS] 0

18. Related works  Deficit Fair Priority Queue (DFPQ) Classifier rtPSnrtPSBE 300 250 500 100 350 200 250 DC[rtPS] 0 DC[nrtPS] 500 DC[BE] 300 Scheduler DC[nrtPS] -250

19. Related works  Preemptive Deficit Fair Priority Queue (PDFPQ) Classifier rtPSnrtPSBE 400 300 100 300 250 500 100 350 200 250 DC[rtPS] 800 DC[nrtPS] 500 DC[BE] 300 Scheduler deadline 120 250 300 450 Q crit =320 Q[rtPS]*0.4

20. Related works  Preemptive Deficit Fair Priority Queue (PDFPQ) packet length of rtPS packet available capacity in the current frame remaining deficit counter of service class which is serviced at that time

21. Proposed adaptive deficit priority queue scheme ADPQ

22. Proposed adaptive deficit priority queue (ADPQ) scheme frame duration current time the arrival time of packet rtPS maximum latency parameter quantum (byte)

23. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 400300100300 250500100 350200250 390ms350ms210ms120ms Enqueue time Q[rtPS] = 800DC[rtPS] = 800 Q[nrtPS] = 500DC[nrtPS] = 500 Q[BE] = 300DC[BE] = 300 T f = 100 ms T now = 500 ms T latency = 300 ms

24. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 400300100300 250500100 350200250 390ms350ms210ms120ms Enqueue time Q[rtPS] = 800DC[rtPS] = 800 Q[nrtPS] = 500DC[nrtPS] = 500 Q[BE] = 300DC[BE] = 300 T f = 100 ms T now = 500 ms T latency = 300 ms 100 + 500 – 210 = 390 > 300 100 + 500 – 120 = 480 > 300 800 + 300 + 400 = 1500 rtPS.threshold

25. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 400300100300 250500100 350200250 390ms350ms210ms120ms Enqueue time Q[rtPS] = 800DC[rtPS] = 1500 Q[nrtPS] = 500DC[nrtPS] = 500 Q[BE] = 300DC[BE] = 300 T f = 100 ms T now = 500 ms T latency = 300 ms

26. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 400300100300 250500100 350200250 390ms350ms210ms120ms Enqueue time Q[rtPS] = 800DC[rtPS] = 1500 Q[nrtPS] = 500DC[nrtPS] = 500 Q[BE] = 300DC[BE] = 300 T f = 100 ms T now = 500 ms T latency = 300 ms

27. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 250500100 350200250 Enqueue time Q[rtPS] = 800DC[rtPS] = 400 Q[nrtPS] = 500DC[nrtPS] = 500 Q[BE] = 300DC[BE] = 300 T f = 100 ms T now = 500 ms T latency = 300 ms

28. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 100 350200250 Enqueue time Q[rtPS] = 800DC[rtPS] = 400 Q[nrtPS] = 500DC[nrtPS] = -250 Q[BE] = 300DC[BE] = 300 T f = 100 ms T now = 500 ms T latency = 300 ms

29. Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 100 200250 Enqueue time Q[rtPS] = 800DC[rtPS] = 400 Q[nrtPS] = 500DC[nrtPS] = -250 Q[BE] = 300DC[BE] = -50 T f = 100 ms T now = 500 ms T latency = 300 ms

30. Simulation

34.  rtPS

35. Simulation  nrtPS

36. Simulation  BE

37. Simulation

39. Conclusion  The uplink scheduling scheme can enhance the performance of rtPS traffic and avoids starvation of low priority service classes  If packets may expire in the next frame, the scheduler transmits these packets in the current frame  ADPQ is a more efficient scheduling scheme for the transmission of delay-sensitive applications than DFPQ and PDFPQ

40. Thank you