An enhanced uplink scheduling scheme forIEEE 802.16 metropolitan area networks

Chia-Yu Yu1 , Sherali Zeadally2, Naveen Chilamkurti3, Ce-Kuen Shieh1

1Institute 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 3Dept. 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 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

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.

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.

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

BS

SS

SS

SS

DL-MAP

Background

Point-to-Multipoint network topology Uplink

BS

SS

SS

SS

UL-MAP

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

Background

Unsolicited Grant Service (UGS) Voice over IP (VoIP)

Res

ourc

e

Time

Background

Real-Time Polling Service (rtPS) Video streaming

Res

ourc

e

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]

800

500

300

Related works

Deficit Fair Priority Queue (DFPQ)Classifier

rtPS nrtPS BE

400

300

100

300

250

500

100

350

200

250

DC[rtPS] 800

DC[nrtPS] 500

DC[BE] 300

Scheduler

Related works

Deficit Fair Priority Queue (DFPQ)Classifier

rtPS nrtPS BE

400

300

100

300

250

500

100

350

200

250

DC[rtPS] 800

DC[nrtPS] 500

DC[BE] 300

Scheduler

DC[rtPS] 0

Related works

Deficit Fair Priority Queue (DFPQ)Classifier

rtPS nrtPS BE

300

250

500

100

350

200

250

DC[rtPS] 0

DC[nrtPS] 500

DC[BE] 300

Scheduler

DC[nrtPS] -250

Related works

Preemptive Deficit Fair Priority Queue (PDFPQ) Classifier

rtPS nrtPS BE

400

300

100

300

250

500

100

350

200

250

DC[rtPS] 800

DC[nrtPS] 500

DC[BE] 300

Scheduler

deadline

120

250

300

450Qcrit=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

400300100300

250500100

350200250

390ms 350ms 210ms 120ms

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 800

Q[nrtPS] = 500 DC[nrtPS] = 500

Q[BE] = 300 DC[BE] = 300

Tf = 100 msTnow = 500 msTlatency = 300 ms

Proposed adaptive deficit priority queue (ADPQ) scheme

rtPS

nrtPS

BE

400300100300

250500100

350200250

390ms 350ms 210ms 120ms

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 800

Q[nrtPS] = 500 DC[nrtPS] = 500

Q[BE] = 300 DC[BE] = 300

Tf = 100 msTnow = 500 msTlatency = 300 ms

100 + 500 – 210 = 390 > 300

100 + 500 – 120 = 480 > 300

800 + 300 + 400= 1500

rtPS.threshold

Proposed adaptive deficit priority queue (ADPQ) scheme

rtPS

nrtPS

BE

400300100300

250500100

350200250

390ms 350ms 210ms 120ms

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 1500

Q[nrtPS] = 500 DC[nrtPS] = 500

Q[BE] = 300 DC[BE] = 300

Tf = 100 msTnow = 500 msTlatency = 300 ms

Proposed adaptive deficit priority queue (ADPQ) scheme

rtPS

nrtPS

BE

400300100300

250500100

350200250

390ms 350ms 210ms 120ms

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 1500

Q[nrtPS] = 500 DC[nrtPS] = 500

Q[BE] = 300 DC[BE] = 300

Tf = 100 msTnow = 500 msTlatency = 300 ms

Proposed adaptive deficit priority queue (ADPQ) scheme

rtPS

nrtPS

BE

250500100

350200250

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 400

Q[nrtPS] = 500 DC[nrtPS] = 500

Q[BE] = 300 DC[BE] = 300

Tf = 100 msTnow = 500 msTlatency = 300 ms

Proposed adaptive deficit priority queue (ADPQ) scheme

rtPS

nrtPS

BE

100

350200250

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 400

Q[nrtPS] = 500 DC[nrtPS] = -250

Q[BE] = 300 DC[BE] = 300

Tf = 100 msTnow = 500 msTlatency = 300 ms

Proposed adaptive deficit priority queue (ADPQ) scheme

rtPS

nrtPS

BE

100

200250

Enqueue time

Q[rtPS] = 800 DC[rtPS] = 400

Q[nrtPS] = 500 DC[nrtPS] = -250

Q[BE] = 300 DC[BE] = -50

Tf = 100 msTnow = 500 msTlatency = 300 ms

Simulation

Simulation

Simulation

Simulation

Simulation

rtPS

Simulation

nrtPS

Simulation

BE

Simulation

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