A Dynamic Uplink/Downlink BWA
and Packet Scheduling
Mechanism in WiMAX
Advisor: Dr. Kai-Wei Ke
Speaker: Ming-Chia Hsieh
Date: 30/07/2006
1
Outline
 Background
 WiMAX
Standard Overview
 Proposed Architecture
 Simulation
 Conclusion
2
WiMAX Overview
 WiMAX?
(Worldwide Interoperability for Microwave Access)
Wireless broadband network connection technique.
Replace last mile.
Cost saving
Easy to deploy
3
Basic WiMAX Network Architecture
Core network
Wireless link
Subscribe Station (SS)
Base Station (BS)
Radio tow er
Subscribe Station
Wired/wireless links
Radio tow er
Radio tow er
Radio tow er
Subscribe Station
Users
4
Outline
 Background
 WiMAX
Standard Introduction
Frame Structure.
Generic / Request Header
Service Classes.
QoS Procedure.
 Proposed Architecture
 Simulation
 Conclusion
5
Frame Structure
N = (Rate x Frame Duration) / 4
Downlink Subframe
Uplink Subframe
adaptive
PS 0
Frame j-1
Frame j
PS N-1
Frame j+1
6
Downlink subframe
Preamble
Preamble
Broadcast Control
DIUC = 0
TDM
DIUC a
DL_MAP
UL_MAP
TDM
DIUC a
TDM
DIUC a
Transition Gap
7
Uplink Subframe
Initial Ranging
Opportunities
(UIUC = 2)
Collision
Access Burst
Request
Contention
Opps
(UIUC = 1)
SS 1
Scheduled
Data
(UIUC = i)
SSTG
Collision
●●●
Transmit/Receive
Transition Gap
BW Request
8
UL/DL Map
Frame n-1
Frame
Control
DL-MAP
UL-MAP
Frame n
DL-MAP
UL-MAP
Downlink
Subframe
Uplink
Subframe
ATDD Split
ATDD Split
9
Outline
 Background
 WiMAX
Standard Introduction
Frame Structure.
Generic / Request Header
Service Classes.
QoS Procedure.
 Proposed Architecture
 Simulation
 Conclusion
10
Generic MAC header
LEN
MSB(3)
1
)
)
)
(
1
1
Rsv (
)
1
CI (
Type (6)
Rsv (
EC(
HT =
0
1
EKS
(2)
)
LEN LSB (8)
CID MSB(8)
CID LSB (8)
HCS (8)
(#) number of bits
11
Bandwidth request header format
EC(
HT =
Type (3)
)
1
1
BR
MSB(11)
(
1
)
BR LSB (8)
CID MSB(8)
CID LSB (8)
HCS (8)
12
Outline
 Background
 WiMAX
Standard Introduction
Frame Structure.
Generic / Request Header
Service Classes.
QoS Procedure.
 Proposed Architecture
 Simulation
 Conclusion
13
Service Classes
 UGS
Constant bit rate , fixed packet length (ex. VoIP)
 rtPS
variable bit rate , variable packet length (ex. MPEG)
 nrtPS
Delay tolerated (ex. FTP)
 BE
Best-Effort (ex. HTTP)
14
Outline
 Background
 WiMAX
Standard Introduction
Frame Structure.
Generic / Request Header
Service Classes.
QoS Architecture
 Proposed Architecture
 Simulation
 Conclusion
15
IEEE 802.16 QoS Architecture
Subscriber Station (SS)
Application
Connection
Request
Connection
Response
Base Station (BS)
Admission Control
(undefined by IEEE)
Connection Classifier
BE
nrtPS
rtPS
UGS
Scheduler
BW
Request
Uplink Packet
Scheduling( UPS)
(Undefined by IEEE)
UL-MAP
Data Transmission
16
IEEE 802.16 Procedures
BS Send
UL/DL Map
BS Send
DL Data
BS Receives
BW Req.
BS Run
BWA
BS Receives
UL Data
SSs Receive
UL/DL Map
SS Receive
UL Data
SSs Send
BW requests
SSs Send
UL Data
17
Outline
 Background
 WiMAX
Standard Introduction
 Proposed Architecture
Proposed Architecture.
Request Maker
Bandwidth Allocation Description
Packet Scheduling Description
 Simulation
 Conclusion
18
Proposed QoS Architecture
BS
Request DB
SS
Request Maker
BE
nrtPS
nrtPS
rtPS
UGS
UGS
rtPS
BW
Request
BE
Classifier
BWA
MAP
Generator
Packet Scheduler
Classifier
DL/UL
MAP
Downstream
Packet
Scheduler
Upstream
19
Problem & Solution of BWA
20
60
50
40
30
20
10
Outline
 Background
 WiMAX
Standard Introduction
 Proposed Algorithm
Proposed Architecture.
Request Maker
Bandwidth Allocation Description
Packet Scheduling Description
 Simulation
 Conclusion
21
Request Maker
SS
BS
Latency
60
Bandwidth request message
CID
001
70
003,005
100
002
CID:001, BW:
BW 50Kb
100Kb
CID:002, BW 50Kb
CID:002,
150Kb
CID:003, BW:
BW 50Kb
CID:004, BW 50Kb
CID:005, BW: 50Kb
Request Maker
Connections
CID:005, BW 50Kb
22
Request Database
CID : 0011 (UGS)
TotalNeeded
7000Kb
TotalDelivery
3000Kb
Arrival Time
70毫秒
100毫秒
130毫秒
140毫秒
Deadline
130毫秒
160毫秒
190毫秒
200毫秒
Bandwidth
1000Kb
2000Kb
500Kb
1000Kb
23
Outline
Background
 WiMAX Standard Introduction
 Proposed Algorithm

 Proposed Architecture.
 Request Maker
 Bandwidth Allocation Description
 Packet Scheduling Description
Simulation
 Conclusion
 Reference

24
Bandwidth Allocation Procedures
DL
Emg(UGS)
UL
Emg(UGS)
DL
NEmg(UGS)
UL
NEmg(UGS)
DL
NEmg(rtPS)
UL
NEmg(rtPS)
DL BE
UL BE
DL
Emg(rtPS)
UL
Emg(rtPS)
DL
nrtPS
UL nrtPS
25
BWA for Non-Real-time
 Sort
By Satisfaction rate.
 Allocate bandwidth from lower satisfaction
Total BW for nrtPS = 2/3 remaining bandwidth.
Individual Station：
Min(Max_BW_For_nrtPS , nrtPS_Loading).
Total BW for BE = remaining – nrtPS
Individual Station:
Min(Max_BW_For_BE , BE_Loading).
26
Outline
 Background
 WiMAX
Standard Introduction
 Proposed Algorithm
Proposed Architecture.
Bandwidth Allocation Description
Packet Scheduling Description
 Performance
evaluation
27
Packet Scheduling
 Restrict
by the DL/UL Map
Gets bandwidth of each Service Classes, and
pick packets in the HOL of the corresponding
queue and sends at appropriated PS
28
Outline
 Background
 WiMAX
Standard Introduction
 Proposed Algorithm
 Performance evaluation-via simulation
 Conclusion
29
Environment Setting
 Packets:
Poison Arrival
 Connection: Poison Arrival
 Compare my algorithm to [3] which is
following the rules of spec.
 BW: 10Mbps
 BS: 1 , SS: 5
 Queue: no limit length
30
Drop Rate (UGS, rtPS)
0.4
0.35
Spec_UGS
Spec_rtPS
Proporsed_UGS
Proporsed_rtPS
Drop Rate(%)
0.3
0.25
0.2
0.15
0.1
0.05
0
0.5
0.6
1
1.3
1.5
1.7
1.9
2.2
Normalized Offered Load
31
Drop Rate (only UGS)
0.01
Spec_UGS
0.009
Proporsed_UGS
0.008
Drop Rate(%)
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0
0.5
0.6
1
1.3
1.5
1.7
1.9
2.2
Normalized Offered Load
32
Delay of real-time service
100
Proporsed_UGS
Spec_UGS
Time(ms)
80
Proporsed_rtPS
Spec_rtPS
60
40
20
0
0.5
0.7
1
1.3
1.5
1.7
1.9
2.2
Normalized Offered Load
33
Time(ms)
Delay of non-real-time service
35000
30000
25000
20000
15000
10000
5000
0
Proporsed_nrtPS
Proporsed_BE
Spec_nrtPS
Spec_BE
0.5
0.7
1
1.3
1.5
1.7
1.9
2.2
Normalized Offered Load
34
Bandwidth util. of Proposed BWA
Proporsed_UGS
Proporsed_rtPS
Proporsed_BE
Total
Proporsed_nrtPS
Throughput(%)
1
0.8
0.6
0.4
0.2
0
0.5
0.6
1
1.3
1.5
1.8
1.9
2.2
Normalized Offered Load(%)
35
Compare of Bandwidth Util.
0.6
Throughput(%)
0.5
0.4
0.3
0.2
Proporsed_UGS
Spec_UGS
0.1
Proporsed_rtPS
Spec_rtPS
0
0.5
0.7
1
1.3
1.5
1.7
1.9
2.2
Normalized Offered Load
36
Fairness of real-time service
Normalized Offered load(50%)
1.02
1
1
Throughput(%)
0.98
0.96
0.94
0.92
0.995
0.99
0.985
UGS
rtPS
0.98
0.9
UGS
0.88
1
2
UGS Average
3
4
rtPS
rtPS Average
5
6
7
Subscribe Station ID
8
9
0.975
1
10
2
UGS_Average
rtPS_Average
3
4
5
6
7
8
9
10
Subscribe Station ID
Normalized Offered load(150%)
1.05
Throughput(%)
Throughput(%)
Normalized Offered load(100%)
1.005
1
0.95
0.9
0.85
UGS
0.8
1
2
Average_UGS
3
4
5
rtPS
6
Average_rtPS
7
8
9
10
Subscribe Station ID
37
Outline
 Background
 WiMAX
Standard Introduction
 Proposed Algorithm
 Simulation
 Conclusion
38
Conclustion
 Provide
Delay and Drop_Rate guarantee for
UGS and rtPS
 nrtPS has more bandwidth than BE
 Even in overloading , nrtPS and BE can get
some bandwidth.
39
Outline
 Background
 WiMAX
Standard Introduction
 Proposed Algorithm
 Simulation
 Conclusion
 Reference
40
reference

IEEE 802.16-2004

GuoSong Chu, Deng Wang, and Shunliang Mei, “A QoS Architecture for the
MAC Protocol of IEEE 802.16 BWA System,” IEEE 2002 International
Conference on Vol. 1, 29 June-1 July 2002 pp. 435-439, 2002.

Dong-Hoon Cho , Jung-Hoon Song, Min-Su Kim, and Kim-Jun Han,
“Performance Analysis of the IEEE 802.16 Wireless Metropolitan Area
Network,” First International Conference on Distributed Frameworks for
Multimedia Applications (DFMA’05), pp. 130-137, 2005.

Kitti Wonghavarawat and Aura Ganz, “Packet Scheduling for QoS support in
IEEE 802.16 broadband wireless access system,” International Journal of
Communication Systems Vol. 16, Issue 1, pp.81-96.

Kin K. Leung and Arty Srivastava, “Dynamic Allocation of Downlink and Uplink
Resource for Broadband Services in Fixed Wireless Networks,” IEEE Journal
on Selected Areas in Communications Vol. 17 No. 5, May 1999.
41
Q&A
42
Virtual Map
6
5
4
3
2
1
SS1UGS
6
5
4
3
2
1
SS2UGS
6
5
4
3
2
1
SS3UGS
6
5
4
3
2
1
SS4UGS
10
9
8
7
6
5
4
3
2
1
SS1rtPS
10
9
8
7
6
5
4
3
2
1
SS2rtPS
10
9
8
7
6
5
4
3
2
1
SS3rtPS
43