1 在 IEEE 系統上提供 QoS 機 制之研究 Student:Hsin-Hsien Liu Advisor:Ho-Ting Wu Date:

2 Outline  Background  Motivation  Call Admission Control & Bandwidth Allocation Algorithm  Simulation result  Conclusion  Future Work

3 Background  IEEE specifies the air interface of fixed and mobile BWA systems  WiMAX (Worldwide Interoperability for Microwave Access) Support QoS High transmission rate Easy and less expensive to deploy

4 The IEEE family of standards Name a802.16d802.16e Completed 2001/122003/012004/062005/12 Mobility Fixed Fixed Portable Mobility Spectrum (GHz) 10~66 LOS 2~11 NLOS 2~11 NLOS 2~6 NLOS Bit Rate (Mbps) 32~ Cell Radius (KM) 2~57~10 2~5

5 IEEE  Topology PMP (Point-to-Multipoint) Mesh  Communication path direction Downlink (BS to SS) Uplink (SS to BS )  Multiplex TDD FDD

6 Service type in IEEE  Unsolicited Grant Service (UGS) Real-time, Constant bit rate, ex VoIP T1  Real-time Polling Service (rtPS) Real-time, Variable bit rate, ex MPEG  Non-real-time Polling Service (nrtPS) Delay-tolerant, require min rate, ex FTP  Best Effort (BE) No QoS guarantees are promised, ex HTTP

7 QoS Architecture of IEEE

8 Motivation  IEEE defines four service flows with different QoS requirement  Except for UGS, the bandwidth allocation mechanism for the other three service flows are left undefined

9 Call Admission Control  Decides whether to accept or reject the connection base on network state  A simple admission control is adopted by using the Minimum Reserved traffic rate [2]

10 Proposed CAC  QoS-Considered CAC Considers each service flow with different QoS requirement  rtPS: Average traffic transmission rate  nrtPS: Minimum reserved traffic rate  BE: always accept

11 Bandwidth Allocation Algorithm  Strict Priority BWA Simple Starvation problem  Deficit Fair Priority Queue (DFPQ) BWA[2] Provides more fairness Refers DWRR Scheduler uses variable deficit counter to visit each non-empty queue

12 DFPQ Procedure 1.Update the parameters, 2.Service the connections in the service flow with the first priority queue a.DeficitCounter[i] ≤ 0 b.Waiting queue is empty c.No available bandwidth left d.It is time sending MAP message

13 DFPQ Procedure (cont.) 3.If Cond. a or Cond. b stands, service other lower priority queues as in Step 2. If there is no lower priority queue, go to Step 2 for anther scheduling round 4.If Cond. c or Cond. d stands, send the MAP message out. Go to Step 1 for next TDD frame

14 Proposed BWA  Fairness-based BWA (FBWA)  First, fundamental QoS bandwidth allocation  Second, fairness bandwidth allocation

15 FBWA Procedure 1.Satisfies rtPS fundamental QoS requirement 2.Satisfies nrtPS fundamental QoS requirement

16 FBWA Procedure (cont.) 3.Allocates fair for each service flow

17 FBWA Procedure (cont.) 4.Each service flow finally gain bandwidth :

18 Simulation parameters setting  Total Bandwidth:10Mbps  Frame Size:10ms  Packet Size:40, 552, 1200bytes  rtPS, nrtPS, BE Data Rate:387, 64, 64Kbits/sec  rtPS, nrtPS, BE Call Duration:240, 120, 60s  rtPS, nrtPS, BE Max. Delay:40, 100, 200ms  rtPS, nrtPS, BE Max. Sustained Traffic Rate: 464.4, 76.8, 76.8Kbits/sec  rtPS, nrtPS Min. Reserved Traffic Rate:309.6, 51.2Kbits/sec

19 Simulation result – CAC Blocking Probability

20 Simulation result – CAC Accepts Connection

21 Simulation result – CAC generates system loading

22 Simulation result – QoS Performance Analysis 1.Different CAC with FBWA 2.Different CAC with DFPQ 3.QoS_CAC with different BWA 4.Rmin_CAC with different BWA 5.QoS_CAC with FBWA vs. Rmin_CAC with DFPQ

23 Different CAC with FBWA - Packet Delay

24 Different CAC with FBWA - Packet Drop Rate

25 Different CAC with DFPQ - Packet Delay

26 Different CAC with DFPQ - Packet Drop Rate

27 QoS_CAC with different BWA – Packet Delay

28 QoS_CAC with different BWA – Packet Drop Rate

29 Rmin_CAC with different BWA – Packet Delay

30 Rmin_CAC with different BWA – Packet Drop Rate

31 QoS_CAC with FBWA vs. Rmin_CAC with DFPQ – Packet Delay

32 QoS_CAC with FBWA vs. Rmin_CAC with DFPQ – Packet Drop Rate

33 Conclusion  Proposed QoS CAC provides QoS guarantee under system overload  Proposed Fairness-based BWA improves fairness

34 Future Work  Downlink and Uplink dynamic bandwidth allocation  Consider real performance of each service flow in time

35 Reference [1]IEEE :Air Interface for Fixed Broadband Wireless Access System. Standard, IEEE standard for local and metropolitan area network [2]Jianfeng Chen, Wenhua Jiao and Hongxi Wang, “ A Service Flow Management Strategy for IEEE Broadband Wireless Access System, ” Lucent Technologies, Bell Labs Research China

36 Q&A