Quality of Service

IEEE 802.16 QoS Architecture2010/03/311LOGO

1Outline 1. Introduction 2. IEEE 802.16 QoS Architecture 5. Conclusion 3. Bandwidth Request 4. Transmission Scheduling2

802.16UL,DLMACFrame2Introduction

802.16 Deployment3

IEEE 802.16UL : SS -> BSDL : BS -> SS3Introduction

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IntroductionService-Specific Convergence Sublayer(CS) :CSCIDMAC CPSMAC Common Part Sublayer(MAC CPS) :802.16 MACBSSSmanagementQoSARQ(Automatic Repeat Request)Security Sublayer : BSSS Physical Layer : OFDMFFT5

Introduction

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( TDD )( Uplink )( Downlink )6Introduction

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downlink subframe uplink subframeDL-MAPPreamble FCH burst profile burst burstburst DL-MAPUL-MAPDCDDL channel descriptorUCDUL channel descriptorframe uplink subframe PDU Ranging(both broadcast and unicast)SS SS BS 7Outline 1. Introduction 2. IEEE 802.16 QoS Architecture 5. Conclusion 3. Bandwidth Request 4. Transmission Scheduling8

QoS mechanismsClassificationMapping from MAC SDU fields (e.g destination IP address) to CID and SFIDSchedulingDownlink scheduling moduleSimple, all queues in BSUplink scheduling moduleQueues are distributed among SSs.Queue states and QoS requirements are obtained through BW requests.Algorithms not defined in standard

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QoS CS16CIDCIDCIDCIDQoSDLULDLBSUL:SSqueuequeueQoS9IEEE 802.16 QoS Architecture

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SSBSBSUL-MAPSSSSpacket schedulerUL-MAPBS

10Service Types

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CBR(Constant bit rate)ThroughputLatency()Jitter()UGSConnectionConnectionSSUGSDSA-/DSC-REQBSQoSBSpiggyback11Service Types (cont.)

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MPEGQoSThroughputLatencyUGSJitterrtPSunicastSSrtPSDSA-/DSC-REQBSQoSBSUL-MAPRequest IESSSSBandwidth stealingpiggyback12Service Types (cont.)Extended rtPS (ErtPS)UGSrtPSEx: silence suppressionVoIPBSUGSunicast grantsSSertPSBSQoSUGSBSSSBSSSbandwidth stealingpiggyback13

802.16eertPSUGSertPSEx: silence suppression()VoIP13Service Types (cont.)

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(latency)Ex: FTPSSnrtPSDSA-/DSC-REQBSQoSBS(1)UL-MAPRequest IESSSSnrtPSnrtPS14Service Types (cont.)

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Ex : emailSSDSA-/DSC-REQBSQoSBSSS(bandwidth request)15Comparison TableQoS CategoryApplicationQoS SpecificationsUGSUnsolicited Grant ServiceVoIPMaximum Sustained RateMaximum LatencyJitter TolerancertPSReal-Time Polling ServiceStreaming Audio or VideoMinimum Reserved RateMaximum Sustained RateMaximum Latency TolerateTraffic PriorityErtPSExtended Real-Time Polling ServiceVoice with Activity Detection (VoIP)Minimum Reserved RateMaximum Sustained RateMaximum Latency TolerateJitter ToleranceTraffic PrioritynrtPSNon-Real-Time Polling ServiceFile Transfer Protocol (FTP)Minimum Reserved RateMaximum Sustained RateTraffic PriorityBEBest-Effort ServiceData Transfer, Web Browsing, etc.Maximum Sustained RateTraffic Prioritypriority16

802.16MACQoSQoS16Poll/Grant Options in Scheduling ServicesSchedulingTypePiggybackRequestBandwidthStealingPollingUGSNot allowedNot allowedPM bit is used to request a unicast poll for bandwidth needs of non-UGS connections.rtPSAllowedAllowedScheduling only allows unicast polling.nrtPSAllowedAllowedScheduling may restrict a service flow to unicast polling via the transmission/request policy; otherwise all forms of polling are allowed.BEAllowedAllowedAll forms of polling allowed.ErtPSAllowedAllowedAll forms of polling allowed17

17UGSContention-based PollingcollisionPiggybackConnectionBSBSQoS802.11QoSUGS UGSPM bit1Outline 1. Introduction 2. IEEE 802.16 QoS Architecture 5. Conclusion 3. Bandwidth Request/Allocation 4. Transmission Scheduling18

SSBSBS18Bandwidth ManagementBandwidth(BW) for a connection is allocated on a demand assignment basis. Unused bandwidth allocation will be withdrawn.Bandwidth is managed via Request/Grant Methods.UGS services arent necessary to be requested,since the resource needs are known in advance. Request can be used for all other services. Bandwidth cant taken from a UGS service (its guaranteed) while possible for other services.

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- BW- UGS,- Grant Units: symbols and subchannels for the OFDM and OFDMA / Minislots for SC(Single Carrier) and Sca- EncodingMAC signaling messagepiggybackgrant management subheader19Unicast pollingPolled Request: polling sent from BSUnicast pollingSent on SSs basic CIDTransmission opportunities in Request IE or Data Grant IEData Grant IE can use a more efficient burst fileRequest IE can only use the Request IE burst file(UIUC=1)Unicast polling of an SS would normally be done by allocating a Data Grant IE directed at its Basic CIDThe transmission of BRs is contention-free

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Unicast pollingBSSSpollingSSBRpollingSSBRSSBR

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Unicast pollingUnicast polling(cont.)21

21Multicast polling and broadcast pollingMulticast polling and broadcast pollingSent on multicast CID or broadcast CIDOnly the members in the polled group will send BRsBRs are transmitted in a contention way and the contention resolution algorithm is appliedBS shall individually poll the SSs periodically who dont have bandwidth allocatedWith only one active UGS connection(BW stealing and piggyback arent allowed), SS set PM bit asking BS to poll the SSIn case no enough bandwidth available for individual polling, broadcast or multicast polling are used22

Multicast pollingbroadcast pollingunicast polling pollingMulticast pollinggrouppollingpollingpollingSSbroadcast pollingpollingSSSS

22Multicast polling and broadcast polling(cont.)Multicast and broadcast polling

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IE information element23Bandwidth StealingBandwidth StealingSS uses a portion of allocated bandwidth for a connection for a connection to send another bandwidth requests rather than sending dataNot allowed for UGS connection

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SSUGS

24Piggyback RequestPiggyback RequestThe bandwidth request is piggybacked onto a MAC PDU on an existing connection with allocated bandwidthNot allowed for UGS connectionThe request is unsuccessful if no grant has been received in next few UL-MAP message

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MAC PDUUL-MAPUGSSSBandwidth Stealing Piggyback Requestpolled. 25Bandwidth Allocation 802.16MACBS schedulerradio interfaceDLUL requested bandwidth, QoS parameters available resources Grant Per Subscriber Station (GPSS)BSSSSubscriber StationSSBSSSSS26

GPSS : SSconnection(802.16-2004)SSBSQoS26Bandwidth Allocation (cont.)DownlinkBSDLQoSBS schedulerSSdownlink burst(s)burst profileUplinkSSBSSSULQoS(UGS, rtPS, ertPS, nrtPS, and BE)BSULunsolicited bandwidth grantspiggyback bandwidth requestunicast polling (polling)contention-based procedures (broadcast or multicast polling)27

27Outline 1. Introduction 2. IEEE 802.16 QoS Architecture 5. Conclusion 3. Bandwidth Request 4. Transmission Scheduling28

28BS scheduler operation for UL

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(SS->BS)BSSSSSBSSSSSRequestUL_MAP29Transmission SchedulingRadio resources have to be scheduled according to the QoS (Quality of Service) parametersUplink Schedulingthe scheduling algorithms can be used :RR (Round Robin)WRR (Weighted Round Robin)WFQ (Weighted Fair Queuing)WFFQ (Worst-case Fair weighted Fair Queuing)VT (Virtual Time)DRR (Deficit Round Robin)DDRR (Distributed Deficit Round Robin)EDF (Earliest Deadline First)30

UL(time slots)QoSUplink : Reserved slots , contention slots (random access slots)

30WRR (Weighted Round Robin)The WRR algorithm is based on the Round Robin algorithm but it takes into account the processing capacity of each waiter.The administrators manually assign a coefficient of performance to each waiter. ( 1, 2 and 3 in the example).

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WRRPacket 31WFQ (Weighted Fair Queuing)

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priority queuing(priority class)(queue)(weight)(round-robin)Weighted fair queuinglower-priority queuestarvationWFQ(Queuing Delay) 32EDF (Earliest Deadline First)

A dynamicscheduling algorithmused inreal-time operating systems.It places processes in apriority queue. Whenever a scheduling event occurs (task finishes, new task released, etc.) the queue will be searched for the process closest to its deadline.If there is a feasible schedule, then EDF produces a feasible schedule33

,real-timeOSpriority queue(,)EDFdeadlineschedulerEDF33Scheduling ExamplePacket scheduling for QoS support in IEEE 802.16 broadband wireless access systemsQoS WiMAXThis scheduling algorithm is proposed to assign:a fixed bandwidth for UGS, using Earliest Deadline First (EDF) technique for rtPS, Weighted Fair Queuing (WFQ) for nrtPS and equal distribution for BE.

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paperdeadlineQoS34BS scheduler operation for DL

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(BS->SS)BSDL(Frame)DL_MAPDL_MAPSSSSDL_MAPBurst35Outline 1. Introduction 2. IEEE 802.16 QoS Architecture 5. Conclusion 3. Bandwidth Request 4. Transmission Scheduling36

ConclusionIEEE 802.16MACsubchannelIEEE 802.16QoS trafficreal-time traffic latencyjitter traffic QoStime slotsQoSWimaxchannelQoSchannelpacketscheduling37

UGSrtPS TrafficUGS Traffic rtPS Traffic 37Future Work3G/LTE, Wi-FiQoS, 38

Reference[1] IEEE Std 802.16-2009[2] A. Ganz, Z.Ganz and K.Wongthavarawat ,Multimedia Wireless Networks: Technologies, Standards, and QoS, Prentice Hall PTR, 2003, ch.7[3] L. Nuaymi, WiMAX: Technology for Broadband Wireless Access, Wiley, 2007, ch.11 [4] K. Wongthavarawat, and A. Ganz, Packet Scheduling for QoS Support in IEEE 802.16 Broadband Wireless Access Systems, International Journal of Communication Systems, Vol. 16, p81-96, 2003[5] K. R. Raghu, S. K. Bose, and M. Ma, Queue Based Scheduling for IEEE 802.16 Wireless Broadband, in Proc. 6th IEEE Int. Conf. ICICS, 2007, pp. 15[6] , , 200939

Q&AThanks for your attention!40

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