Survey of Admission Control of Supporting VoIP Services in IEEE 802.11e QoS-enabled WLAN

1

Survey of Admission Control of Survey of Admission Control of Supporting VoIP Services in Supporting VoIP Services in

IEEE 802.11e QoS-enabled WLAIEEE 802.11e QoS-enabled WLANN

R93725003 R93725003 卓德忠卓德忠 R93725010 R93725010 鍾佳芳鍾佳芳

2 Jan. 20062 Jan. 2006

2

Outline Outline

Introduction Introduction Admission ControlAdmission Control Parameterized EDCAParameterized EDCA Conclusions Conclusions

3

Introduction Introduction

Motivation Motivation Introduction of 802.11e featuresIntroduction of 802.11e featuresIntroduce the reference design of Introduce the reference design of HCCA in 802.11eHCCA in 802.11e

4

Motivation Motivation

802.11e is an enhanced QoS support in 802.11e is an enhanced QoS support in WLANsWLANs The most promising framework among QThe most promising framework among Q

oS enhancements of WLANsoS enhancements of WLANs The contention-based MAC access schThe contention-based MAC access sch

eme is hard to provide quality of serviceme is hard to provide quality of service (QoS) assurance for VoIP services.e (QoS) assurance for VoIP services.

5

Introduction of 802.11eIntroduction of 802.11e

IEEE 802.11 WG, “Draft Supplement to Standard for Telecommunications and Information Exchange between Systems-LAN/MAN Specific Requirements — Part 12: Wireless MAC and PHY Specifications: MAC Enhancements for QoS,” IEEE 802.11e/draft 12.0, Nov. 2004.

Qiang Ni,”Qiang Ni,”Performance Analysis and EnhPerformance Analysis and Enhancements for IEEE 802.11e Wireless Netwancements for IEEE 802.11e Wireless Networksorks,” in IEEE Network, July/August 2005,” in IEEE Network, July/August 2005

6

Introduction of 802.11eIntroduction of 802.11e A new MAC layer function called the hybrid

coordination function (HCF) is proposed. HCF uses a contention-based channel access

method, also called enhanced distributed channel access (EDCA)

Polling-based HCF-controlled channel access (HCCA) method

Transmission opportunity (TXOP) refers to a time duration during which a QSTA is allowed to transmit a burst of data frames EDCA-TXOP HCCA-TXOP

7

MAC Architecture for QoSMAC Architecture for QoS

L.W Lim, R. Malik, P.Y. Tan, C. Apichaichalermwongse, K. Ando, Y. Harada, L.W Lim, R. Malik, P.Y. Tan, C. Apichaichalermwongse, K. Ando, Y. Harada, ““A QoS scheduler for IEEE 802.11e WLANsA QoS scheduler for IEEE 802.11e WLANs”, First IEEE Consumer Commu”, First IEEE Consumer Communications and Networking Conference, 2004. Jan 2004, pp.199 – 204nications and Networking Conference, 2004. Jan 2004, pp.199 – 204

8

HCCA FeaturesHCCA Features

1. Different traffic classes called traffic streams (TSs) are introduced in HCCA.

2. QSTA is not allowed to transmit a packet if the frame transmission cannot finish before the next beacon

3. TXOPLimit is used to bound the transmission time of a polled QSTA.

In order to initiate a TS connection, a QSTA sends a traffic specification (TSPEC) to the QAP. A TSPEC describes the QoS requirements of a TS Mean Data Rate, Nominal MSDU Size Maximum Service Interval or Delay Bound

9

Reference scheduling Reference scheduling algorithm in 802.11ealgorithm in 802.11e

The schedule for an admitted stream is calculated in three steps.

1. Calculation of the Scheduled Service Interval (SI).

2. Calculation of TXOP duration for a given SI 3. Admission control scheme

1. Service Interval (SI) calculates the minimum of all Maximum Service

Intervals for all admitted streams. Let this minimum be "m".

chooses a number lower than "m" that is a submultiple of the beacon interval.

Ex. MSIEx. MSI11=15ms, MSI=15ms, MSI22=20ms, beacon interval = 100=20ms, beacon interval = 100=>SI = 10ms=>SI = 10ms

10


2.2. Calculation of TXOP durationCalculation of TXOP duration Mean Data Rate (ρ) Mean Data Rate (ρ) Nominal MSDU Size (LNominal MSDU Size (Lii) from the negotiated TS) from the negotiated TS

PECPEC Scheduled Service Interval (SI) calculated in the Scheduled Service Interval (SI) calculated in the

first step, first step, Ni: the number of MSDUs that arrived at

the Mean Data Rate during the SI

11


Parameters Parameters Nominal MSDU Size (LNominal MSDU Size (Lii) from the negotiated TS) from the negotiated TS

PECPEC MinMin Physical Transmission Rate (R), Physical Transmission Rate (R), Maximum allowable MSDU size (M) Maximum allowable MSDU size (M) Overheads in time units (O): IFSs, ACKs, and COverheads in time units (O): IFSs, ACKs, and C

F-Polls F-Polls

3.3. Admission ControlAdmission Control

12

Admission Admission ControlControl

AC for CBR trafficAC for CBR trafficAC for VBR trafficAC for VBR traffic

13

Survey of Admission Survey of Admission ControlControl

Deyun Gao, Jianfei Cai and King Ngi Ngan, Deyun Gao, Jianfei Cai and King Ngi Ngan, ““Admission Control in IEEE 802.11e WirelAdmission Control in IEEE 802.11e Wireless LANsess LANs,”in IEEE Network, July/August 2,”in IEEE Network, July/August 2005005

Admission Control for Admission Control for CBRCBR Traffic Traffic physical-rate-based admission control physical-rate-based admission control PRBACPRBAC

Admission Control for Admission Control for VBRVBR Traffic Traffic Effective TXOP durationEffective TXOP duration Variable Service IntervalVariable Service Interval

14

Admission Control for Admission Control for CBRCBR TrafficTraffic

Gao, D.; Cai, J.; Zhang, L., “Gao, D.; Cai, J.; Zhang, L., “Physical rPhysical rate based admission control for HCCA ate based admission control for HCCA in IEEE 802.11e WLANsin IEEE 802.11e WLANs”, Advanced I”, Advanced Information Networking and Applicationformation Networking and Applications, 2005. AINA 2005ns, 2005. AINA 2005 physical-rate-based admission control (physical-rate-based admission control (PRBAC)PRBAC) long-term average physical rates for admission clong-term average physical rates for admission c

ontrolontrol instantaneous physical rates to distribute TXOPsinstantaneous physical rates to distribute TXOPs

15

Admission Control for Admission Control for CBRCBR TrafficTraffic

16

The maximum numbers of The maximum numbers of VoIP traffic streamVoIP traffic stream

Woo-Yong Choi, “Woo-Yong Choi, “A Centralized MAC-LevA Centralized MAC-Level Admission Control Algorithm for Traffic el Admission Control Algorithm for Traffic Stream Services in IEEE 802.11eWireless LStream Services in IEEE 802.11eWireless LANsANs”, International Journal of Electronics ”, International Journal of Electronics and Communications, 2004and Communications, 2004

obtain the maximum numbers of VoIP traffic streams that can be admitted to IEEE 802.11a/e, IEEE 802.11b/e and IEEE 802.11g/e wireless LANs for various delay requirements.

17

Arrival PatternArrival Pattern

Di: the constant inter-arrival of burst Li: burst size, [0, maximum burst size] Pi: the length of the burst period,

18

Arrival Pattern (cond)Arrival Pattern (cond) Li: burst size, [0, maximum burst size] PRi: the peak data rate MRi: the mean data rate Pi: the length of the burst period, Di: the constant inter-arrival of burst

19

Max Queue SizeMax Queue Size

B: the maximum queue state Si: constant service rate Pi: the length of the burst period PRi: the peak data rate

PRi-Si Si

^

20

Max delayMax delay

Ti : the maximum delay provide the traffic stream with the con

stant service rate, Si (bits/second).

==>

Admission ControlAdmission Control ΣSi < available service rate (AR)ΣSi < available service rate (AR)

21

Numerical examplesNumerical examples

Burst length Pi = 1.5 secBurst length Pi = 1.5 sec Burst inter-arrival time Di = 1 secBurst inter-arrival time Di = 1 sec IMBE codec:4.8KbpsIMBE codec:4.8Kbps User payload of VoIP MPDU is 88 bitsUser payload of VoIP MPDU is 88 bits Number of MPDU = 4.8*1.5/88 = 82Number of MPDU = 4.8*1.5/88 = 82 Burst size Li Burst size Li

= 4.8*1.5 + 82*(UDP, IP and MAC)= 4.8*1.5 + 82*(UDP, IP and MAC)= 7200 + 82*(16 + 224 + 240) = 46560 bits= 7200 + 82*(16 + 224 + 240) = 46560 bits

22


Peak data rate PRi = Li/Pi = 31KbpsPeak data rate PRi = Li/Pi = 31Kbps Mead data rate = PRi*1.5/(1.5+1) = 18.6Mead data rate = PRi*1.5/(1.5+1) = 18.6

KbpsKbps Actual available service rate RActual available service rate R

R=11.34Mbps(a, g), 2.2Mbps(b)R=11.34Mbps(a, g), 2.2Mbps(b)

23


5 times

About 35 VoIP pairs

24

Admission control for Admission control for VBRVBR traffic traffic

W.F. Fan, D.Y. Gao, D. H.K. Tsang and B. Bensaou, "W.F. Fan, D.Y. Gao, D. H.K. Tsang and B. Bensaou, "AAdmission Control for Variable Bit Rate traffic in IEEE 8dmission Control for Variable Bit Rate traffic in IEEE 802.11e WLANs02.11e WLANs,” to be appewed in The Joint Conferen,” to be appewed in The Joint Conference of 10th Asia-Pacific Conference on Communicationce of 10th Asia-Pacific Conference on Communications and 5th International Symposium on Multi-Dimensis and 5th International Symposium on Multi-Dimensional Mobile Communications, Aug. 2004onal Mobile Communications, Aug. 2004 introducing introducing Effective TXOP durationEffective TXOP duration ( (the ne

cessary TXOPs which can statistically guarantee that the packet loss probability is less than a threshold )

guarantee the packet loss rateguarantee the packet loss rate

25

Admission control for Admission control for VBRVBR traffic traffic

W. F. Fan;Tsang, D.H.K.; Bensaou, B., “W. F. Fan;Tsang, D.H.K.; Bensaou, B., “AAdmission Control for Variable Bit Rate traffdmission Control for Variable Bit Rate traffic using variable Service Interval in IEEE 8ic using variable Service Interval in IEEE 802.1 le WLANs02.1 le WLANs”, ICCCN 2004. Proceedings”, ICCCN 2004. Proceedings

using using Variable Service IntervalVariable Service Interval avoid over-guarantee on packet delay (wavoid over-guarantee on packet delay (w

hich with large delay bound)hich with large delay bound) guarantee the packet loss rateguarantee the packet loss rate The larger the service interval, the less TThe larger the service interval, the less T

XOP durations requiredXOP durations required

26

Parameterized Parameterized EDCAEDCA

Comparison of HCCA and EDCAComparison of HCCA and EDCAAdmission Control algorithmAdmission Control algorithmResource Allocation algorithmResource Allocation algorithmPerformance EvaluationPerformance Evaluation

27

Parameterized EDCAParameterized EDCA

Chun-Ting Chou, Sai Shankar N and Kang Chun-Ting Chou, Sai Shankar N and Kang G. Shin, “G. Shin, “Achieving Per-Stream QoS with Achieving Per-Stream QoS with Distributed Airtime Allocation and AdmissDistributed Airtime Allocation and Admission Control in IEEE 802.11e Wireless LANsion Control in IEEE 802.11e Wireless LANs,, “ “ IINFOCOMNFOCOM 2005 2005

Chun-Ting Chou, Kang G. Shin and Sai Shankar, “Distributed Control of Airtime UsaDistributed Control of Airtime Usage in Multi-rate Wireless LANsge in Multi-rate Wireless LANs,” under review of the IEEE/ACM Transactions on Networking

28

Comparison of HCCA and Comparison of HCCA and EDCAEDCA

Challenges of HCCAChallenges of HCCA The HC needs to re-compute the service sThe HC needs to re-compute the service s

chedule whenever a new traffic stream is chedule whenever a new traffic stream is added to, or deleted from a WLANadded to, or deleted from a WLAN

When two WLANs using HCCA operate on When two WLANs using HCCA operate on the same channel, it requires additional cthe same channel, it requires additional coordination between themoordination between them 802.11k802.11k

29

Comparison of HCCA and Comparison of HCCA and EDCA EDCA (cont’d)(cont’d)

Challenges of EDCAChallenges of EDCA A quantitative control of stations’ A quantitative control of stations’

medium occupancy cannot be achieved medium occupancy cannot be achieved via the current EDCAvia the current EDCA

The link adaptation allows stations to The link adaptation allows stations to vary their PHY transmission rate based vary their PHY transmission rate based on the link condition makes the airtime on the link condition makes the airtime usage control even harderusage control even harder

30

AdmissionAdmission Control Control AlgorithmAlgorithm

Guaranteed Rate (g) Guaranteed Rate (g) -----------------Appendix A-----------------Appendix A

C is the channel capacityC is the channel capacity Dependent on PHY ratesDependent on PHY rates

We must consider multi-rateWe must consider multi-rate 802.11 802.11 environmentenvironment airtime ratio(rairtime ratio(ri,ji,j))

31

AdmissionAdmission Control Control AlgorithmAlgorithm

New conditionNew condition Overall conditionsOverall conditions

EA: Efficient Airtime RatioEA: Efficient Airtime Ratio

32

Allocation of AirtimeAllocation of Airtime

EDCAEDCA ControlControl the the TXOP Limit TXOP Limit of each stations of each stations

Same EDCA parametersSame EDCA parameters ControlControl the frequency of station’s access the frequency of station’s access

to the wireless mediumto the wireless medium Same TXOP (access duration)Same TXOP (access duration)

33

Controlling the TXOP Controlling the TXOP LLimitimit

TXOPTXOP

NNi i : : The number of The number of data frames per data frames per one accessone access

Transmission time :Transmission time :

Ni Ni Ni

iM

Mii Tr

TrN

34

Controlling the TXOP Controlling the TXOP LLimitimit (cont’d)(cont’d)

ExampleExample LLii = 600, 600, 1200, 1200 bytes = 600, 600, 1200, 1200 bytes

RRii = 48, 48, 48, 24Mbps = 48, 48, 48, 24Mbps

TTi i =100, 100, 200, 400(T=100, 100, 200, 400(TMM) ) secsec

rrii = 0.1, 0.2, 0.2, 0.1 = 0.1, 0.2, 0.2, 0.1(r(rMM)) NNii = 4, 8, 4, 1 = 4, 8, 4, 1

35

Controlling Controlling the Athe Access ccess FFrequencyrequency

TXOP limitTXOP limit

Access frequency approximationAccess frequency approximation[24][24]

[24] Chun-Ting Chou, Kang G. Shin and Sai Shankar, “Distributed Control of Airtime Usage in Multi-rate Wireless LANs,” under review of the IEEE/ACM Transactions on Networking

j

i

j

i

r

r

AF

AF

36

Controlling Controlling the Athe Access ccess FFrequencyrequency (cont’d)(cont’d)

ExampleExample LLii = 600, 600, 1200, 1200 bytes = 600, 600, 1200, 1200 bytes RRii = 48, 48, 48, 24Mbps = 48, 48, 48, 24Mbps TTi i =100, 100, 200, 400(T=100, 100, 200, 400(TMM) ) secsec NNii = 4, = 4, 44, , 22, 1, 1 rrii = 0.1, 0.2, 0.2, 0.1 = 0.1, 0.2, 0.2, 0.1

37

System EfficiencySystem Efficiency

t =35 s

37 Mbps

N=16

38

TTime-varying ime-varying TTransmission ransmission RRatesates

54Mbps → 24Mbps

39

ConclusionConclusion

HCCA HCCA High system efficiency (higher EA)High system efficiency (higher EA) Contention freeContention free with admission control mechanisms, the with admission control mechanisms, the

delay and packet loss rate of VoIP / other delay and packet loss rate of VoIP / other multimedia streams are guaranteed. multimedia streams are guaranteed.

However, the influence of Jitter is not discHowever, the influence of Jitter is not discussed here.ussed here.

40

Conclusion Conclusion (cont’d)(cont’d)

Parameterized Parameterized EDCAEDCA No control overhead in overlapping No control overhead in overlapping

multiple LANsmultiple LANs No adjustment for changeNo adjustment for change

HCCA needs to reHCCA needs to re--compute schedulecompute schedule Easy adaptation of extra airtime for the Easy adaptation of extra airtime for the

change of station’s PHY ratechange of station’s PHY rate

41

ReferenceReference IEEE 802.11 WG, “Draft Supplement to Standard for T

elecommunications and Information Exchange between Systems-LAN/MAN Specific Requirements — Part 12: Wireless MAC and PHY Specifications: MAC Enhancements for QoS,” IEEE 802.11e/draft 12.0, Nov. 2004.

Qiang Ni,”Qiang Ni,”Performance Analysis and Enhancements Performance Analysis and Enhancements for IEEE 802.11e Wireless Networksfor IEEE 802.11e Wireless Networks,” in IEEE Networ,” in IEEE Network, July/August 2005k, July/August 2005

Deyun Gao, Jianfei Cai and King Ngi Ngan, “Deyun Gao, Jianfei Cai and King Ngi Ngan, “AdmissioAdmission Control in IEEE 802.11e Wireless LANsn Control in IEEE 802.11e Wireless LANs,”in IEEE Ne,”in IEEE Network, July/August 2005twork, July/August 2005

Gao, D.; Cai, J.; Zhang, L., “Gao, D.; Cai, J.; Zhang, L., “Physical rate based admisPhysical rate based admission control for HCCA in IEEE 802.11e WLANssion control for HCCA in IEEE 802.11e WLANs”, Adva”, Advanced Information Networking and Applications, 2005. nced Information Networking and Applications, 2005. AINA 2005AINA 2005

42

ReferenceReference W.F. Fan, D.Y. Gao, D. H.K. Tsang and B. Bensaou, "W.F. Fan, D.Y. Gao, D. H.K. Tsang and B. Bensaou, "Admission Control Admission Control

for Variable Bit Rate traffic in IEEE 802.11e WLANsfor Variable Bit Rate traffic in IEEE 802.11e WLANs,” to be appewed i,” to be appewed in The Joint Conference of 10th Asia-Pacific Conference on Communican The Joint Conference of 10th Asia-Pacific Conference on Communications and 5th International Symposium on Multi-Dimensional Mobile tions and 5th International Symposium on Multi-Dimensional Mobile Communications, Aug. 2004Communications, Aug. 2004

W. F. Fan;Tsang, D.H.K.; Bensaou, B., “W. F. Fan;Tsang, D.H.K.; Bensaou, B., “Admission Control for Admission Control for Variable Bit Rate traffic using variable Service Interval in IEEE Variable Bit Rate traffic using variable Service Interval in IEEE 802.1 le WLANs802.1 le WLANs”, ICCCN 2004. Proceedings”, ICCCN 2004. Proceedings

Woo-Yong Choi, “Woo-Yong Choi, “A Centralized MAC-Level Admission Control A Centralized MAC-Level Admission Control Algorithm for Traffic Stream Services in IEEE 802.11eWireless LAlgorithm for Traffic Stream Services in IEEE 802.11eWireless LANsANs”, International Journal of Electronics and Communicatio”, International Journal of Electronics and Communications, 2004ns, 2004

Chun-Ting Chou, Sai Shankar N and Kang G. Shin, “Chun-Ting Chou, Sai Shankar N and Kang G. Shin, “Achieving Achieving Per-Stream QoS with Distributed Airtime Allocation and AdmissPer-Stream QoS with Distributed Airtime Allocation and Admission Control in IEEE 802.11e Wireless LANsion Control in IEEE 802.11e Wireless LANs, “ , “ IINFOCOMNFOCOM 2005 2005

Chun-Ting Chou, Kang G. Shin and Sai Shankar, “Distributed Distributed Control of Airtime Usage in Multi-rate Wireless LANsControl of Airtime Usage in Multi-rate Wireless LANs,” under review of the IEEE/ACM Transactions on Networking

43

Appendix A. Guaranteed Appendix A. Guaranteed Rate Rate

Dual-token bucket filterDual-token bucket filter

Tokens arrive at Peak Data Rate

Tokens arrive at Mean Data Rate

MAC frame buffer

Bucket size B = σ (1-ρ/P)

σ

Bits

Time

d

mean rate : ρ

peak rate : P

Guaranteed rate : g

Arrival curve : A(t)

Arriving traffic stream Data frames drained at Guaranteed Rate

error

Documents

Survey of Admission Control of Supporting VoIP Services in IEEE 802.11e QoS-enabled WLAN