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
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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
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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)
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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)
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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
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DL-MAP and UL-MAP
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Downlink Subframe
Broadcast
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Uplink Subframe
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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).
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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
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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
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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
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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
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Attributes of a Service Flow
• Service Flow ID• CID• Provisioned Qos Parameter Set• Admitted QoS Parameter Set• Active QoS Parameter Set• Authorization Module
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Relationship of QoS Parameter Set
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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
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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
• 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 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
Two Stage Bandwidth Allocation
UGS
rtPS
nrtPS
BE
Down Stream(DL/UL MAP)
Up Stream
BS SS
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 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
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
Pairing Call Admission Control
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 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
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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.
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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.
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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.
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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
• 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 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
Two Stage Bandwidth Allocation
Page 37
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 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)
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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 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
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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
60 secondsExponential
30 secondsExponential
Traffic Generation and Simulation Environment
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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
Traffic Generation and Simulation Environment
Performance Metric• Call Blocking Probability :
• Packet Drop Rate :
• Packet Delay :
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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
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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
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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 DL Total Calls ;
UL Total Calls UL Blocking Calls ;
UL Total Calls DL Total Calls ;
UL Blocking Calls DL Blocking Calls ;
Call Blocking ProbabilityNonPairing CAC vs Pairing CAC
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Pairing CAC vs NonPairing CAC
4/29/2008Page 51
UGS rtPS
nrtPS BE
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