A Study of the Bandwidth Management Architecture over IEEE 802.16 WiMAX

A Study of the Bandwidth Management Architecture over IEEE 802.16 WiMAX

Student : Sih-Han ChenAdvisor : Ho-Ting WuDate : 2008.5.6

Outline

• Introduction of IEEE802.16 QoS• Proposed QoS System Architecture

– Pairing Call Admission Control– Bandwidth Borrowing on CAC level– Two Stage Bandwidth Allocation– Mandatory Packet Scheduling Algorithm

• Performance Evaluation• Conclusion and Future Work

4/29/2008Page 2

4/29/2008Page 3

Wireless TechnologiesBandwidth

1 Gbps

100 Mbps

10 Mbps

1 Mbps

PAN LAN MAN WAN<1m 10m 100m Up to 50Km Up to 80Km

802.15.1Bluetooth

Wi-Fi802.11a/g

Wi-Fi802.11b

802.15.3High Speed

WirelessPAN

Wi-MAX802.16

(802.16-2004 & 802.16e)

4G

3G

2.5G

IEEE 802.15 IEEE 802.11 IEEE 802.16 3GPP

PAN: Personal area networksMAN: Metropolitan area networks

LAN: Local area networks Wide area networks

4/29/2008Page 4

IEEE 802.16 Operation ModePoint to MultiPoint (PMP) Mode Mesh Mode (Optional)

(a) (b)

Mesh SS

Mesh SS WiMAXBackhaulnetwork

SS

SS

SS

SSBS

Mesh SS

Base Station (BS)

4/29/2008Page 5

MAC Common Part Sublayer

• Defines multiple-access mechanism

• Functions ：– connection establishment– connection maintenance– Call admission control – bandwidth request– bandwidth allocation

MAC Common Part Sublayer

(MPC)

4/29/2008Page 6

IEEE 802.16 TDD frame structureFrame n-1 Frame n Frame n+1

DL Subframe UL Subframe

Preamble FCH DL-Burst #1

DL-Burst #2-4

DL-Burst #5

DL-Burst #6

TTG

RTG

Initialranging

BWrequest

UL-Burst #1

UL-Burst #2

DLFP DL-MAP UL-MAP MAC messages, Mac PDUs

IEIE IE IE IE IE IE IE IE IE

Preamble FCH DL-Bursts#1-4 DL-Burst #5 DL-Burst #6 Initialranging

BWrequest

UL-Burst #1

UL-Burst #2

Preamble(optional)

MACPDU

MACPDU

Pad PreambleMACPDU

MACPDU

Midamble(optional)

MACPDU

MACPDU

Pad

每個UL-Burst內的資料，都必須來自同一台SS每個DL-Burst內的資料，有可能是要送給不同SS

IE IE

4/29/2008Page 7

DL-MAP and UL-MAP

4/29/2008Page 8

Downlink Subframe

Broadcast

4/29/2008Page 9

Uplink Subframe

4/29/2008Page 10

Media Acces Control (MAC)

• Connection orienteded– Service Flow(SF)– Connection ID (CID)

• Channel access:– UL-MAP

• Defines uplink channel access• Defines uplink data burst profiles

– DL-MAP• Defines downlink data burst profiles

– UL-MAP and DL-MAP are both transmitted in the beginning of each downlink subframe (FDD and TDD).

4/29/2008Page 11

Bandwidth Request

• SSs may request bandwidth in 3 ways:– Use the ”contention request opportunities”

interval upon being polled by the BS (unicast, multicast or broadcast poll)

– Send a standalone MAC message called ”BW request” in an already granted slot

– Piggyback a BW request message on a data packet

4/29/2008Page 12

Bandwidth Allocation• BS grants/allocates bandwidth in one of two

modes– Grant Per Subscriber Station (GPSS)– Grant Per Connection (GPC)

• Decision based on requested BW, QoS parameters and available resources

• Grants are realized through the UL-MAP

4/29/2008Page 13

Service Classes

• Unsolicited Grant Services (UGS): – Constant Bit Rate (CBR) services, – T1/E1 emulation, and Voice Over IP (VoIP)

• Real-Time Polling Services (rtPS): – real-time services variable size data packets– MPEG video or VoIP with silence suppression.

• Non-Real-Time Polling Services (nrtPS): – Used for delay tolerant traffic requiring some minimum data rate– FTP

• Best Effort Services (BE) :– Used for streams with no rate guarantees.– WEB , HTTP

IEEE 802.16 QoS Provisioning

• Service Flow QoS Scheduling• Dynamic Service Establishment• Two-phase Activation

4/29/2008Page 14

Service Flow• The central concept of the MAC protocol• A service flow is a unidirectional flow of

packets that is provided a particular QoS.• SS and BS provide this QoS according to the

QoS parameter set.• Existing in both uplink and downlink and may

exist without being activated.• Must have a 32bit SFID, besides admitted and

active status also have a 16-bit CID

4/29/2008Page 15

Attributes of a Service Flow

• Service Flow ID• CID• Provisioned Qos Parameter Set• Admitted QoS Parameter Set• Active QoS Parameter Set• Authorization Module

4/29/2008Page 16

Relationship of QoS Parameter Set

4/29/2008Page 17

Authorized QoS Parameter Set = Provisioned QoS Parameter Set(SFID)

Admitted QoS Parameter Set(SFID & CID)

Active QoS Parameter Set(SFID & CID)

Type of Service Flow• Provisioned Service Flows

– Provided by external network management system– Admitted and Active QoSParamSet are NULL

• Admitted Service Flows– Reserved resource according AdmittedQoSParamSet,

but not yet activated– First Stage of two-phase activation model

• Active Service Flows– Active QoS Parameter Set is non-NULL – Second Stage of two-phase activation model

4/29/2008Page 18

Dynamic Service Management• Dynamic Service Activate (DSA)

– Activate a service flow

• Dynamic Service Change (DSC)– Change an existing service flow

• Dynamic Service Delete (DSD)– Delete a service flow

4/29/2008Page 19

Dynamic Service Establishment

4/29/2008Page 20

DSA message flow SS-initiated DSA message flow BS-initiated

(a) (b)

SS

DSX-RVD

DSA-REQ

(Without SFID and CID)

BS

DSA-RSP

DSA-ACK

SS

DSA-REQ

BS

DSA-ACK

DSA-RSP

(SFID and Transport CID)

(SFID and Transport CID)

Outline




4/29/2008Page 21

Proposeed QoS Architecture

4/29/2008Page 22

Two Stage Bandwidth Allocation

Downlink Packet Scheduler

Cor

e N

etw

ork

ApplicationsPair Call Admission Control

BandwidthBorrowingAgent

Uplink Packet Scheduler

Downlink Data Traffic

Connection Request

Connection Response

UGS

rtPS

nrtPS

BE

UplinkData Traffic


UGS

rtPS

nrtPS

BE

Down Stream(DL/UL MAP)

Up Stream

BS SS

Outline




4/29/2008Page 23

Basic Bandwidth Reserved Scheme

Analysis

Maximum Sustained Traffic Rate

1. 每條被允入的連線都能達到 100 %服務品質保證。2. 系統所允入的連線數目最少，且頻寬的使用率也是最低。3. 對於 Variable Bit Rate類型的連線，有較嚴重的頻寬浪費。4. 適合用於 Constant Bit Rate 類型的連線。

Average Traffic Rate 1. 定義上，長期 (Long term)時間內能滿足各連線的需求，但短期內無法達到 100 % 的服務品質保證。

2. 被允入的連線數目提高，且能提供一定品質的服務。3. 對於有時效性的連線封包，在突爆量時封包的丟棄率

(Drop rate)會稍高。Minimum Reserved Traffic Rate

1. 只能提供每條連線最小保留頻寬的服務。2. 被允入的連線數目最多，但每條連線都只享有最低的服務品質，可能造成過長的時間延遲問題。

3. 較適合沒有時效性的連線。4/29/2008Page 24

Bandwidth Reservation Scheme

Abbreviations Definition

Total System Bandwidth Resource

Remaining Available System Bandwidth Resource

Connection Request

Peak Traffic Rate of DL Connection Request

Average Traffic Rate of DL/UL Connection Request

Min Traffic Rate of DL/UL Connection Request

Reserved Bw for DL/UL Connection after CAC

totalRavailableR

/DL UL

PeakRateCr/DL UL

AvgRateCr/DL UL

MinRateCr/DL UL

BwRsv

Cr

Pairing Call Admission Control


4/29/2008Page 26

DL ULavailable Bw Bw

DL ULavailable available Bw Bw

For each pair of Connection Request

if( + ){ Accept the pair of calls;

= - - ;}else{ if( Is Bandwidth Borrowing Enable ??? )

Rsv RsvR

Rsv RsvR R

{ Execute Bandwidth Borrowing Algorithm ; } else { Reject the call; }}

Is UGS?

Each Pair Connection Request

/ /DL UL DL UL

Bw PeakRateRsv Cr

/ /

/

2

DL UL DL UL

DL UL PeakRate AvgRate

Bw

Cr CrRsv

/ /

/

2

DL UL DL UL

DL UL AvgRate MinRate

Bw

Cr CrRsv

//

2

DL ULDL UL MinRateBw

CrRsv

Is rtPS?

Is nrtPS?

Is BE?

DL UL

BwRsv

Ravailable >=

Y

Y

Y

Y

N

N

NEnable BandwidthBorrowing ?

Y

Accept Pair Call

N

Reject Call

N

Y

Go Bandwidth Borrowing Agent


Outline




4/29/2008Page 28

4/29/2008Page 29

Is UGS?

Each Pair Connection Request from CAC Module

Is rtPS?

Is nrtPS?

Is BE?

Y

Y

Y

Y

N

N

N

Borrow from

BE Cons

Borrow from

nrtPS Cons

Borrow from

rtPS Cons

Borrow from

BE Cons

Borrow from

nrtPS ConsReject

Reject

Reject

Accept

SuccessSuccess

Success

Fail Fail

Fail

Fail Fail

AcceptSuccess Success

Conception Bandwidth Borrowing

Abbreviations Definition

Total numbers of rtPS , nrtPS or BE connection

in system

The current reserved bandwidth for connection i

The low bound of reserved bandwidth for

connection i.

Amount of bandwidth are needed to be

borrowed from system.

In system, How many bandwidth can be

borrowed from rtPS, nrtPS and BE individually

/ /rtPS nrtPS BENi

currentRsv

borrowB

_

i

low boundRsv

Bandwidth Borrowing on CAC Level

/ /rtPS nerPS BE

CreditB

Operation of Bandwidth Borrowing• Amount of bandwidth are needed to be

borrowed from system

• In system, the bandwidth can be borrowed from rtPS, nrtPS and BE individually

4/29/2008Page 31

DL UL

borrow availableBw BwRsv RsvB R

_( )

r t P S/nrtPS/BEk kr t P S/nrtPS/BE

C r e d i t c u r r e n t low boundi k

NRsv RsvB

Operation of Bandwidth Borrowing

• If , the bandwidth borrowing from each exiting BE connection.

• Else, try to borrow bandwidth from nrtPS.

4/29/2008Page 32

BE

borrow C r e d i tB B

_

_1

( )

( )B E

i i

c u r r e n t low bound

borrow

i i

c u r r e n t low boundi

NRsv Rsv

BRsv Rsv

Operation of Bandwidth Borrowing

• If , the bandwidth borrowing from each exiting nrtPS connecion, after borrow from all .

• Else, try to borrow bandwidth from rtPS.

4/29/2008Page 33

BE n r t P S

borrow C r e d i t C r e d i tB B B

BE

CreditB

_

_1

( )

( )n r t P S

j j

BEc u r r e n t low bound

borrow C r e d i t

j j

c u r r e n t low boundj

NRsv Rsv

B BRsv Rsv

Operation of Bandwidth Borrowing• If ,the bandwidth

borrowing from each exiting rtPS connecion, after borrow from all and and .

• Else, reject the connection request.

4/29/2008Page 34

BE

CreditB

BE n r t P S r t P S

borrow C r e d i t C r e d i t C r e d i tB B B B

nrtPS

CreditB

_

_1

( )

( )r t P S

k k

BE n r t P Sc u r r e n t low bound

borrow C r e d i t C r e d i t

k k

c u r r e n t low boundk

NRsv Rsv

B B BRsv Rsv

Outline




4/29/2008Page 35

Two Stage Bandwidth Allocation• Stage One：

– Give the guarantee reserved bandwidth at most.– Obtain fairness, guarantee each connection shares the

resource.

• Stage Two ：– Allocate the remaining bandwidth.– Partial fairness. Use weighting ( i.e. rtPS:nrtPS:BE =

2:1:1 ) to share the bandwidth.4/29/2008Page 36

min UL_Req+DL_Req , UL_Rsv+DL_Rsv

蒐集所有的BW Rep 和

DL_Data

能滿足當下所有的

BW Req + DL_Data???

分配所要求的頻寬

還有剩餘頻寬嗎?

平均分配給UL_Link的所有

連線

針對每組連線先滿足基本的頻寬min{ UP需求 + Down需求， UP保留 + Down保留 }

還有剩餘頻寬嗎?

依個別類型連線之不足額的比例以(2:1:1)方式公平分配

以四種服務類別為依據，統計在DL方向每一種服務類別總共得到多少頻寬

以SS為單位，統計每台SS總共得到多少頻寬

依DL與UL統計所得頻寬

N

Y

Y

N

Y

Downlink Uplink

N


Page 37

Outline



• Performance Evaluatioin• Conclusion and Future Work

4/29/2008Page 38

Mandatory Packet Scheduling Algorithm

Scheduling Service

Mandatory Algorithm

UGS First In First Out (FIFO)rtPS Earliest Dead Line First

(EDF)nrtPS Weighted Fair Queue (WFQ)BE Round Robin (RR)

4/29/2008Page 39

Outline




4/29/2008Page 40

Traffic Generation and Simulation Environment

4/29/2008Page 41

Simulation Environment Values

Number of BS 1

Number of SS 10 - 100

Total Bandwidth 64 Mbps

Each SS Data Source 4 (UGS/rtPS/nrtPS/BE)

Total Simulation Time 1000 Seconds

Frame Duration 10 ms

Page 42 4/29/2008

UGS rtPS nrtPS BEApplication VoIP Video FTP EmailAverage Data Rate

64 KbpsDL： 387Kbps

UL： 38.7Kbps

DL： 320Kbps

UL： 32Kbps192 Kbps

Maximum Sustained Traffic Rate

64 KbpsDL： 464.4Kbps

UL： 46.44Kbps

DL： 384Kbps

UL： 38.4Kbps230.4Kbps

Minimum Reserve Traffic Rate 64 Kbps

DL： 309.6Kbps

UL： 30.96Kbps

DL： 256Kbps

UL： 25.6Kbps153.6Kbps

Accept Call Criteria Max Rate

64Kbps

(Max+Avg)/2DL： 425.7Kbps

UL： 42.57Kbps

(Avg+Min)/2DL： 288Kbps

UL： 28.8Kbps

Min / 276.8Kbps

Low Bound of Guarantee Bw Max Rate Avg Rate Min Rate 0

Call Inter Arrival Time

9 SecondsExponential

37.5 SecondsExponential

30 SecondsExponential

4.5 SecondsExponential

Call Duration 240 secondsExponential

240 secondsExponential




Page 43 4/29/2008

UGS rtPS nrtPS BE

Maximum Latency

20 ms 40 ms 100 ms 200 ms

Schedule Scheme FIFO EDF WFQ RR

Packet Size160 BytesFixed-Size

DL： 1935 B

UL： 193.5 BExponential

64-1518 BytesUniform

64-1518 BytesUniform

Packet Fragment 80 Bytes 1518 Bytes 1518 Bytes 1518 Bytes

Packet Inter Arrival Time

20 msFixed Period

20 msFixed Period

20 msPareto(Shape=1.15)

33msPareto(Shape=1.06)

Reserve Bw Per frame (Non Bandwidth Borrowing)

80 BytesDL： 532.125 B

UL： 53.2125 B

DL： 360 B

UL： 36 B96 Bytes


Performance Metric• Call Blocking Probability :

• Packet Drop Rate :

• Packet Delay :

4/29/2008Page 44

UL Blocking Calls DL Blocking Calls

UL Total Calls DL ToTal Calls

Total Dropped Packets

Total Generated Packets

Queuing Time of Total Transmitted Packet

Total Transmitted Packets

NonPairing CAC vs Pairing CAC

4/29/2008Page 45

Definition of Pairing CAC

• Accepted :

• Reject :

UL Total Calls DL Total Calls ；

UL Total Calls UL Blocking Calls ；

BS SS

BidirectionalConnection Request

(Uplink and Downlink DSA)

Accepted or Reject

Definition of NonPairing CAC Accept Call

BS SSWiMAXBackhaulNetwork

Connection Request (Uplink DSA)

Accepted Provisionally

Connection Request (Downlink DSA)

Accepted

Accepted Finally

Round Trip Time of Downlink Connection Request

Definition of NonPairing CAC Reject Call

4/29/2008Page 48

Non-Pairing CAC First Type of Connection Fail

Non-Pairing CAC Second Type of Connection Fail

(a) (b)

BS SS BS SSWiMAXBackhaulNetwork

Connection Request (Uplink DSA)

Accepted Provisionally

Connection Request (Downlink DSA)

Reject

Reject Finally and Release Reserved Bw

Round Trip Time of Downlink Connection

Request

Definition of NonPairing CAC

4/29/2008Page 49

• Accepted :

• First Type of Connection Fail :

• Second Type of Connection Fail :


UL Total Calls UL Blocking Calls ；


UL Blocking Calls DL Blocking Calls ；

Call Blocking ProbabilityNonPairing CAC vs Pairing CAC

4/29/2008Page 50

Pairing CAC vs NonPairing CAC

4/29/2008Page 51

UGS rtPS

nrtPS BE

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A Study of the Bandwidth Management Architecture over IEEE 802.16 WiMAX

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