Upload
yardan
View
37
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Routing and Admission Control in IEEE 802.16 Distributed Mesh Networks. Tzu-Chieh Tsai Dept. of Computer Science National Chengchi University Taipei, Taiwan. Outline. Introduction Problems Related Work Our Routing and CAC Algorithm Simulations Conclusion. Outline. Introduction - PowerPoint PPT Presentation
Citation preview
1
Routing and Admission Control in IEEE 802.16 Distributed Mesh
NetworksTzu-Chieh Tsai
Dept. of Computer ScienceNational Chengchi University
Taipei, Taiwan
2
Outline
Introduction
Problems
Related Work
Our Routing and CAC Algorithm
Simulations
Conclusion
3
Outline
IntroductionWireless Mesh Networks
IEEE 802.16 Mesh Mode
Problems
Related Work
Our Routing and CAC Algorithm
Simulations
Conclusion
4
Introduction—Wireless Mesh Networks
5
Introduction—Wireless Mesh Networks
Ad-hoc network basisSelf organization
Fault tolerance
Scalability
Lower infrastructure cost
Wider coverage
Standard activities802.11s (in progress)
802.15.5 (in progress, mainly in PHY)
802.16Mesh mode is already included in standards.
6
IEEE 802.16 mesh mode
Internet
BS
BSSS
SS
7
IEEE 802.16 mesh mode
TerminologyMesh Base Station (MBS or BS)Mesh Subscriber Station (MSS or SS)Extended neighborhood (2-hop neighbors)
Defers from PMP mode (Point to Multi-Point)Traffic can occur directly between SSsOnly TDD is supported in MeshFrame format
Not compatible
A frame is composed withControl subframe
Network control subframeSchedule control subframe
Data subframe
8
IEEE 802.16 Mesh Mode Frame Formats
Frame n-1 Frame n Frame n+1
NENT NCFG NCFG … NCFG
Network Control subframe
CSCH CSCF CSCF … DSCH
Schedule Control subframe
Frame n-1 Frame n Frame n+1
NENT NCFG NCFG … NCFG
Network Control subframe
CSCH CSCF CSCF … DSCHCSCH CSCF CSCF … DSCH
Schedule Control subframe
Data subframe
slot slot slot … slot slot
Data subframe
slot slot slot … slot slot
Frame n-1 Frame n Frame n+1
NENT NCFG NCFG … NCFG
Network Control subframe
CSCH CSCF CSCF … DSCHCSCH CSCF CSCF … DSCH
Schedule Control subframe
Frame n-1 Frame n Frame n+1
NENT NCFG NCFG … NCFG
Network Control subframe
CSCH CSCF CSCF … DSCHCSCH CSCF CSCF … DSCH
Schedule Control subframe
Data subframe
slot slot slot … slot slot
Data subframe
slot slot slot … slot slot
9
IEEE 802.16 Mesh Mode
Scheduling mechanism:
CentralizedUsing MSH-CSCH, MSH-CSCF msgs.
DistributedCoordinated
Uncoordinated– Both using MSH-DSCH msgs.– Mesh Distributed Scheduling messages
10
IEEE 802.16 Mesh Mode
In distributed coordinated mesh mode, each node periodically broadcasts :
MSH-NCFGMesh-Network Config
Exchanges the basic parameters between SSs
– ID of BS, hop count to BS, number of neighbors, …
MSH-DSCH msgs.Mesh-Distributed Scheduling
Both using Mesh election algorithm to determined next transmission time.
11
IEEE 802.16 Mesh Mode
The information elements (IEs) of MSH-DSCH msgs.
Scheduling IE:Determines the next transmission time of MSH-DSCH msgs.
To avoid collision of MSH-DSCH msgs.
Request IE:Convey the resources over a link
Availability IE:Carry the information of the available resources
Grant IE:Convey the confirm information of the resources
12
IEEE 802.16 Mesh Mode—3-way Handshake
MSH-DSCH: Request
Src. sends to dest. along with MSH-DSCH: Availibilities
Indicate the empty timeslots of src. Node
MSH-DSCH: Grant
Dest. Chooses a range of empty timeslots according to MSH-DSCH:request, and,
Dest. replies with this msg.
MSH-DSCH: Grant
Src. Copies the received grant and sends it back to destination node
Requester Granter
MSH-DSCH:RequestAnd
MSH-DSCH:availbility
MSH-DSCH:Grant
MSH-DSCH:Grant
Requester Granter
MSH-DSCH:RequestAnd
MSH-DSCH:availbility
MSH-DSCH:Grant
MSH-DSCH:Grant
13
IEEE 802.16 QoS Classes
Four QoS classesUnsolicited Grant Service (UGS)
Real-time Polling Service (rtPS)
Non-real-time Polling Service (nrtPS)
Best Effort (BE)
Class name Traffic type Application
UGS Real-time Constant Bit Rate (CBR) Voice over IP (VoIP)
rtPS Real-time Various Bit Rate (VBR) Real-time video
nrtPS Non-real-time Bandwidth-sensitive FTP
BE Non-real-time HTTP, Telnet
14
IEEE 802.16 Mesh Mode –QoS
Mesh mode uses CID (Connection ID) to define the service parameters
ReliabilityTo re-transmit or not
PriorityThe priority of the connection
Drop PrecedenceWhen congestion occurs, the likelihood of dropping the packets
15
Outline
Introduction
Problems
Related Work
Our Routing and CAC Algorithm
Simulations
Conclusion
16
Problems
QoS provisioning for each class, we need:A Routing Method suitable in 802.16 distributed mesh mode
A way to do admission control
The above 2 things are not specified in the standard
Our solutions:SWEB (Shortest-Widest Efficient Bandwidth) metrics for routing
TAC (Token-bucket based Admission Control)
17
Outline
Introduction
Problems
Related Work
Our Routing and CAC Algorithm
Simulations
Conclusion
18
Related Work
In [3], a token-based call admission control and a math model is proposed under IEEE 802.16 PMP mode
The bandwidth of a flow is estimated as
2fd and f
dm where,
1-m
bfr i
ii
i
ii
19
Related Work -Token Bucket Mechanism
Token bucket parametersToken rate r
Bucket size b
In time duration t, the output volume of data would be:
, at most.
Token rate r
Packet Queue
Bucket size b
Output
Token rate r
Packet Queue
Bucket size b
Output
btr *
20
Related Work
In [7], routing metrics “ETX” is proposedExpected Transmission Count
Under 802.11 ad-hoc networks
Forwarding delivery ratio: ,reverse delivery ratio:
Determined by sending probe packets
ETX is calculated as:
fd rd
rf ddETX
*
1
21
Outline
Introduction
Problems
Related Work
Our Routing and CAC AlgorithmRouting
Modified 3-way handshake
TAC algorithm
Simulations
Conclusion
22
Routing and CAC algorithms
Static Routing is suitable in IEEE 802.16 mesh networks:
Stations do not move or have the minimum mobility
Topology and channel conditions do not change severely
IEEE 802.16d standard does not support mobility
Providing QoS of one flow over multiple routes can be in-efficient and difficult
23
Routing
To minimize delay and achieve good throughputPi,j: packet error rate of link (i,j)
Ci,j: Capacity of link (i,j)
A bandwidth of a link is
Node 1 Node 2 Node 3 Node 4
2,1p 3,2p 4,3p
2,1C 3,2C 4,3C
)1( ,, jiji pC
24
Routing
Capacity of all links = C
Effective bandwidthPath1
=C*min((1-0.1),(1-0.2),(1-0.1))/2
=0.4*C
Path2=0.25C
Path3=0.4C
Path 3 is preferable.divided by hopCount
Path1=0.4C/3
Path3=0.4C/2
S D
0.1
0.2
0.1
0.5 0.5
0.2 0.2
Path1
Path2
Path3
25
SWEB Routing
Routing is done off-line.
Path metric=
h: hop countSWEB (Shortest-Widest Efficient Bandwidth) Metrics
Node 1 Node 2 Node 3 Node 4
2,1p 3,2p 4,3p
2,1C 3,2C 4,3C
h
pCpCpC hhhh 1
2
))1(),...,1(),1(min( 1,1,3,23,22,12,1
26
Outline
Introduction
Problems
Related Work
Our Routing and CAC AlgorithmRouting
Modified 3-way handshake
TAC algorithm
Simulations
Conclusion
27
Modified 3-way handshake
To shorten the call setup time, we modified the 3-way handshake
Original 3-way handshake:
Requester Granter
MSH-DSCH:RequestAnd
MSH-DSCH:availbility
MSH-DSCH:Grant
MSH-DSCH:Grant
Requester Granter
MSH-DSCH:RequestAnd
MSH-DSCH:availbility
MSH-DSCH:Grant
MSH-DSCH:Grant
28
Modified 3-way handshake
Original 3-way handshake in a multi-hop environment
29
Modified 3-way handshake
30
Outline
Introduction
Problems
Related Work
Our Routing and CAC AlgorithmRouting
Modified 3-way handshake
TAC algorithm
Simulations
Conclusion
31
Bandwidth Estimation
Assume that each flow is controlled by the token bucket mechanism.Each flow reports the parameters when it is initiated:
r: token rateb: bucket sized :Delay requirement (for real-time traffics)
Using token bucket, the required bandwidth is:
Over-estimated.
f
bfr
32
Bandwidth Estimation
t t+7f
ri*f ri*f ri*f
t+4ft t+7f
ri*f ri*f ri*f
t+4f
S
D
33
Bandwidth Estimation
t+6f
ri*f ri*f ri*f ri*f
t+12ft+5f
bi
ri*f ri*f ri*f ri*f ri*f
t+9ft+6f
ri*f ri*f ri*f ri*f
t+12ft+5f
bi
ri*f ri*f ri*f ri*f ri*f
t+9f
S
D
34
Bandwidth Estimation
t+6f
ri*f ri*f ri*f ri*f
t+12ft+5f
ri*f ri*f ri*f ri*f ri*f
t+9f
bi/
mi-1bi/
mi-1
t+6f
ri*f ri*f ri*f ri*f
t+12ft+5f
ri*f ri*f ri*f ri*f ri*f
t+9f
S
D
35
Bandwidth Estimation
We estimate the Max. volume transmitted by a real-time flow in a frame as:
,where
ii
i hf
dm
i
ii m
bfr
36
TAC (Token-bucket Based Admission Control) algorithm
Goal:Guarantee delay requirements for real-time flows
Avoid starvation
To guarantee delayUse the above-mentioned bandwidth estimation.
To avoid starvationsSet minimum usage of each class:
CBR_min, VBR_min, and BE_min.
37
TAC algorithm
Concept:
38
TAC algorithm
Fields in CID (connection ID) are used to identify QoS levels
Priority
(3 bits)
Reliability
(1 bit)
Drop Precedence
(2 bits)
CBR 7 0 0
CBR_DG 4 0 1
VBR 6 0 0
VBR_DG 3 0 2
BE 5 1 0
BE_DG 2 1 3
39
Outline
Introduction
Problems
Related Work
Our Routing and CAC Algorithm
SimulationsRouting
TAC
Conclusion
40
SimulationsParameters
ParametersFrame length = 8 ms
Slot capacity = 144 bytes
Data timeslots =165
QPSK coding rate =3/4
676 OFDM symbols per frameFor CTRL subframe=16
For DATA subframe=660
4 OFDM symbols per slot
41
SimulationsRouting
Topology16 nodes
4 km * 4km
Radio range = 1.5 km
Node 16 is the MBS.
42
SimulationsRouting
98.316.1106.491.1198.382.004.2
25456.102501.481.1132.55
86.02559.082.02525.656.177.225.6432.6581.1152.58
55.1266.1132.1191.102598.3
56.60156.109.485.60156.104.7256.177.259.04
82418.6023.182.0456.5554.5904.211.1118.1304.211.1023.1
4421.1156.12504.22523.1
04.204.204.24054.57
56.156.125.682.023.101.1
77.289.397.2411.477.242522.1102.0
77.225.677.225.604.277.267.1104.2249.6
56.5254.5977.223.11.22525.6998.0
08.1267.1177.2425.652.5871.13
4425.62577.211.1104.2098.24
125.6125.682.0252525404.204.2
23.101.423.169.0
Packet error rate over links: ( in 1/100 )
43
SimulationsRouting
ETX
44
SimulationsRouting
Shortest Path
45
SimulationsRouting
Proposed Routing metrics
46
SimulationsRouting
Since we primarily focus on VBR traffics, VBR traffics are compared across 3 routing trees.
Throughput
Delay
Jitter
The number of each class traffic flow is ranging from 5 to 25.
47
SimulationsRouting
Throughput
0
1000
2000
3000
4000
5000
6000
7000
8000
5 10 15 20 25
number of flows
bps
ETX
Shortest
SWEB
48
SimulationsRouting
Avg. Delay
0
10
20
30
40
50
60
70
5 10 15 20 25
number of flows
ms
ETX
Shortest
SWEB
49
SimulationsRouting
J itter
0
5
10
15
20
25
30
35
5 10 15 20 25
Number of flows
tim
e (m
s)
ETX
shortest
SWEB
50
Outline
Introduction
Problems
Related Work
Our Routing and CAC Algorithm
SimulationsRouting
TAC
Conclusion
51
Simulationsparameters
Minimum usage:CBR 10 timeslots
VBR 40 timeslots
BE 75 timeslots
Token rate
(bps)
Bucket size
(bits)
Delay requirement
CBR 960 64 40 ms
VBR 2000k 4000 80 ms
BE 750k 2000 --
52
SimulationsCAC
(wimax) throughput
01000
20003000
40005000
60007000
8000
5 10 15 20 25
number of flows
bps
CBR
VBR
BE
total
(TAC) throughput
010002000300040005000600070008000
5 10 15 20 25
number of flows
bps
CBR
VBR
BE
total
53
SimulationsCAC
avg. delay
0
10
20
30
40
50
60
70
5 10 15 20 25
number of flows
dela
y tim
e (m
s)
CBR
VBR
BE
avg. delay
0
20
40
60
80
100
120
140
5 10 15 20 25
number of flows
dela
y tim
e (m
s)
CBR
VBR
BE
CBRDG
VBRDG
BEDG
WiMax TAC is added
54
SimulationsCAC
exceeds delay requirement
02468
101214
5 10 15 20 25
number of flows
perc
entag
e (%
)
CBR
VBR
exceeds delay requirement
01234567
5 10 15 20 25
number of flows
perc
entag
e (%
)
CBR_DG
VBR_DG
WiMax TAC is added
55
Outline
Introduction
Problems
Related Work
Our Routing and CAC Algorithm
Simulations
Conclusion
56
Conclusion
We proposes a CAC (called TAC) mechanism thatguarantee the delay requirements of real-time traffic flows, and
Avoid starvations
A simple routing metric SWEB that is suitable for IEEE 802.16 mesh networks
A modified 3-way handshake thatReduces call setup time
57
Reference[1] IEEE, “IEEE Standard for Local and metropolitan area networks Pa
rt 16: Air Interface for Fixed Broadband Wireless Access Systems”, IEEE standard, October 2004.
[2] Harish Shetiya and Vinod Sharma, "Algorithms for routing andcentralized scheduling to provide QoS in IEEE 802.16 mesh networks",Proceedings of the 1st ACM workshop on Wireless multimedianetworking and performance modeling ,WMuNeP '05. Pages: 140-149.[3] Tzu-Chieh Tsai, Chi-Hong Jiang, and Chuang-Yin Wang, "CAC andPacket Scheduling Using Token Bucket for IEEE 802.16 Networks", inJournal of Communications (JCM, ISSN 1796-2021), Volume : 1 Issue :
2, 2006. Page(s):30-37. Academy Publisher.
58
Reference[4] Fuqiang LIU, Zhihui ZENG, Jian TAO, Qing LI, and Zhangxi LIN,"Achieving QoS for IEEE 802.16 in Mesh Mode",8th InternationalConference on Computer Science and Informatics, Salt Lake City, USA[5] Hung-Yu Wei, Samrat Ganguly, Rauf Izmailov, and Zygmunt J. Haa
s, "Interference-Aware IEEE 802.16 WiMax Mesh Networks", inProceedings of 61st IEEE Vehicular Technology Conference (VTC 200
5 Spring).[6] Min Cao, Qian Zhang, Xiaodong Wang, and Wenwu Zhu, "Modelling
and Performance Analysis of the Distributed Scheduler in IEEE 802.16 Mesh Mode", Proceedings of the 6th ACM international symposium on Mobile ad hoc networking and computing
59
Reference[7] Douglas S. J. De Couto, Daniel Aguayo, John Bicket , and Robert M
orris, “A High-Throughput Path Metric for Multi-Hop Wireless Routing”, ACM MobiCom ’03.