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

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

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

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 [5] Lera, A.; Molinaro, A.; Pizzi, S. “Channel-Aware Scheduling for QoS and Fairness Provisioning in IEEE /WiMAX Broadband Wireless Access Systems,” IEEE Network, Volume 21, Issue 5, Page(s):34 – 41, Sept.-Oct

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 Broadband Wireless Access Systems in TDD Mode,” ICC 2005, Page(s): , May [8] Safa, Haidar; Artail, Hassan; Karam, Marcel; Soudah, Rawan; Khayat, Samar; “New Scheduling Architecture for IEEE Wireless Metropolitan Area Network,” IEEE/ACS International Conference on Computer Systems and Applications, 2007, Page(s): , May 2007.

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

Background  Point-to-Multipoint network topology

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

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

Background  IEEE 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

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

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

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

Related works  QoS architectures

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

Related works  Deficit Fair Priority Queue (DFPQ) Classifier rtPSnrtPSBE DC[rtPS] 800 DC[nrtPS] 500 DC[BE] 300 Scheduler

Related works  Deficit Fair Priority Queue (DFPQ) Classifier rtPSnrtPSBE DC[rtPS] 800 DC[nrtPS] 500 DC[BE] 300 Scheduler DC[rtPS] 0

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

Related works  Preemptive Deficit Fair Priority Queue (PDFPQ) Classifier rtPSnrtPSBE DC[rtPS] 800 DC[nrtPS] 500 DC[BE] 300 Scheduler deadline Q crit =320 Q[rtPS]*0.4

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

Proposed adaptive deficit priority queue scheme ADPQ

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

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE ms350ms210ms120ms 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

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE ms350ms210ms120ms 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 – 210 = 390 > – 120 = 480 > = 1500 rtPS.threshold

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE ms350ms210ms120ms 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

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE ms350ms210ms120ms 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

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 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

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 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

Proposed adaptive deficit priority queue (ADPQ) scheme rtPS nrtPS BE 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

Simulation

 rtPS

Simulation  nrtPS

Simulation  BE

Simulation

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

Thank you