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A Study of the Bandwidth Management
Architecture over IEEE 802.16 WiMAX
Student : Sih-Han Chen ( 陳思翰 )
Advisor : Ho-Ting Wu ( 吳和庭 )
Date
: 2008.07.25
Outline
Background and Motivation
Proposed QoS System Architecture
Call Admission Control (CAC)
Pairing CAC
Bandwidth Borrowing on CAC level
Two Stage Bandwidth Allocation
Performance Evaluation
Conclusion and Future Work
2008/07/25
Page 2
Background
Fixed WiMAX (Worldwide Interoperability for
Microwave Access)
Specified by IEEE 802.16 d
Wireless MAN Network
High transmission rate and coverage (75Mbps ,50km)
Support QoS
Cost saving and easy to deploy
Replace last mile (like ADSL)
2008/07/25
Page 3
MAC Common Part Sublayer
Defines multiple-access
mechanism
Functions ：
Connection establishment
Connection maintenance
Call admission control
Bandwidth request
Bandwidth allocation
Packet scheduling
2008/07/25
MAC Common Part Sublayer
(MAC CPS)
Page 4
IEEE 802.16 TDD Frame Structure
Frame n-1
Frame n
Frame n+1
DL Subframe
Preamble
FCH
DL-Burst
#1
DLFP
IE IE IE IE
UL Subframe
DL-Burst
#5
DL-Burst
#2-4
DL-MAP
UL-MAP
MAC
PDU
Pad
BW
request
UL-Burst
#1
R
UL-Burst
T
#2
G
MAC messages, Mac PDUs
IE IE IE
IE IE IE IE IE
Preamble FCH DL-Bursts#1-4 DL-Burst #5 DL-Burst #6
Preamble MAC
(optional) PDU
T
Initial
T ranging
G
DL-Burst
#6
Ranging
Opportunity
Preamble MAC
(optional) PDU
These MAC PDUs which are in each DL-Burst
Will possibly be sent to different SS
2008/07/25
BW
request
UL-Burst
#1
MAC Midamble MAC
PDU (optional) PDU
UL-Burst
#2
MAC
PDU
Pad
These MAC PDUs which are in each UL-Burst
have to come from one SS
Page 5
Service Classes
Feature
UGS
(Unsolicited Grant
Service)
rtPS
(Real-Time Polling
Service)
nrtPS
(Non-Real-Time Polling
Service)
BE
(Best Effort)
2008/07/25
Application
•Real Time
•Constant Bit Rate
•T1/E1
•VoIP
•Real Time
•Variable Bite Rate
•MPEG video
•Non-Real Time
•Variable Bite Rate
•FTP
•Non-Real Time
•No QoS guarantee
•HTTP
•Email
Page 6
Dynamic Service Establishment
SS-initiated：DSA message flow
BS-initiated：DSA message flow
SS
SS
BS
(Without SFID and CID)
DSA-RE
Q
DSX-RVD
DSA-RSP
BS
(SFID and Transport CID)
DSA-REQ
DSA-RS
P
(SFID and Transport CID)
DSA-AC
K
(a)
2008/07/25
DSA-ACK
(b)
Page 7
Motivation
IEEE 802.16 only defined the basic QoS
signaling architecture.
The detail internal algorithm was left as the
responsibility of implementers.
Call admission control
Bandwidth allocation
Packet scheduling
Undefined
!!!
Pairing connection property
Uplink and downlink connections must coexist for
many network application. (e.g. VoIP, FTP, P2P…)
2008/07/25
Page 8
Outline
Background and Motivation
Proposed QoS System Architecture
Call Admission Control (CAC)
Pairing CAC
Bandwidth Borrowing on CAC level
Two Stage Bandwidth Allocation
Performance Evaluation
Conclusion and Future Work
2008/07/25
Page 9
Proposed QoS Architecture
SS
Core Network
BS
Bandwidth
Borrowing
Agent
Pair Call
Admission
Control
Connection Request
Applications
Connection Response
Uplink
Data Traffic
Downlink
Data Traffic
UGS
UGS
rtPS
nrtPS
Two Stage
Bandwidth
Allocation
rtPS
Two Stage
Bandwidth
Allocation
nrtPS
BE
BE
Downlink Packet Scheduler
2008/07/25
Up Stream
(Bandwidth Request)
Down Stream
(DL/UL MAP)
Uplink Packet Scheduler
Page 10
Pairing Call Admission Control
Symbol
B
Rsv
Cr
Cr
Cr
available
X
Definition
Remaining Available System Bandwidth Resource
Reserved Bw for Connection, ( X = DL or UL )
Bw
X
PeakRate
X
Peak Traffic Rate of Connection Request, ( X = DL or UL)
Average Traffic Rate of Connection Request, ( X = DL or UL)
AvgRate
X
Min Traffic Rate of Connection Request, ( X = DL or UL)
MinRate
2008/07/25
Page 11
Pairing Call Admission Control
Each Pair
Connection
Request
Is UGS?
Y
Rsv
X
Bw
Cr PeakRate
X
Bavailable >=
Rsv
Y
X
Bw
N
Y
Is rtPS?
Rsv
X
Bw
Cr
X
Cr AvgRate
PeakRate
2
N
Y
Is nrtPS?
Rsv
X
Bw
Cr
X
Cr MinRate
X
AvgRate
N
Enable
Bandwidth
Borrowing ?
N
Y
2008/07/25
Rsv
X
Bw
Y
2
N
Is BE?
Accept
Pair Call
X
Cr
X
MinRate
2
Reject Call
Go
Bandwidth
Borrowing
Agent
Page 12
Range of Bandwidth Reservation
Service
Upper Bound of
Type Reserved Bandwidth
UGS
Low Bound of
Reserved Bandwidth
Peak rate
Peak rate
rtPS
( Peak rate + Avg rate)
2
Avg rate
nrtPS
( Avg rate + Min rate)
2
BE
2008/07/25
Min rate
2
Min rate
0
Page 13
Bandwidth Borrowing on CAC Level
Definition
Symbol
Rsv
Rsv
i
current
i
low _ bound
B
B
borrow
X
Credit
2008/07/25
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.
(X = rtPS , nrtPS or BE )
Page 14
Operation of Bandwidth Borrowing
Calculate the bandwidth that are needed to
be borrowed from system
B
Rsv
Rsv
R available
borrow
Bw
Bw
DL
UL
In system, the bandwidth can be borrowed
from rtPS, nrtPS and BE individually
B
2008/07/25
X
Credit
NX
( Rsv
i k
k
current
Rsv low _ bound )
k
Page 15
Bandwidth Borrowing Flow Chart
Pair Connection Request
from CAC Module
Success
Borrow
from existing
BE Cons
Is UGS? Y
Success
Failure
Success
Borrow
Failure
from existing
nrtPS Cons
Borrow
from existing
rtPS Cons
Reject
Failure
Accept
N
Success
Is rtPS?
Accept
Borrow
from existing
BE Cons
Y
Success
Failure
Borrow
from existing
nrtPS Cons
Success
Failure
Borrow
from existing
rtPS Cons
Is nrtPS?
Y
N
Reject
Y
Is BE?
2008/07/25
Page 16
Reject
Failure
Example of Bandwidth Borrowing (BB)
BS
SS
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
Pairing UGS DSA
Total require 160Kbps(80x2)
1
BE
100 Kbps
50 Kbps
50 Kbps
2
nrtPS
150 Kbps
100 Kbps
50 Kbps
Now System available Bw= 0
Start to BB operations at BS.
3
rtPS
300 Kbps
150 Kbps
150 Kbps
4
rtPS
200 Kbps
150 Kbps
50 Kbps
After Bandwidth
Borrowing Operation
2008/07/25
Page 17
Example of Bandwidth Borrowing (BB)
BS
SS
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
Pairing UGS DSA
Total require 160Kbps(80x2)
1
BE
100 Kbps
50 Kbps
50 Kbps
2
nrtPS
150 Kbps
100 Kbps
50 Kbps
Now System available Bw= 0
Start to BB operations at BS.
3
rtPS
300 Kbps
150 Kbps
150 Kbps
4
rtPS
200 Kbps
150 Kbps
50 Kbps
(1) Borrow from exiting BE
connections.
160 – 50 = 110 Kbps
After Bandwidth
Borrowing Operation
Existing Connections in System
2008/07/25
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
1
BE
50 Kbps
50 Kbps
0 Kbps
Page 18
Example of Bandwidth Borrowing (BB)
BS
SS
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
Pairing UGS DSA
Total require 160Kbps(80x2)
1
BE
100 Kbps
50 Kbps
50 Kbps
2
nrtPS
150 Kbps
100 Kbps
50 Kbps
Now System available Bw= 0
Start to BB operations at BS.
3
rtPS
300 Kbps
150 Kbps
150 Kbps
4
rtPS
200 Kbps
150 Kbps
50 Kbps
(1) Borrow from exiting BE
connections.
160 – 50 = 110 Kbps
(2) Borrow from exiting
nrtPS connections.
110 – 50 = 60 Kbps
2008/07/25
After Bandwidth
Borrowing Operation
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
1
BE
50 Kbps
50 Kbps
0 Kbps
2
nrtPS
100 Kbps
100 Kbps
0 Kbps
Page 19
Example of Bandwidth Borrowing (BB)
BS
SS
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
Pairing UGS DSA
Total require 160Kbps(80x2)
1
BE
100 Kbps
50 Kbps
50 Kbps
2
nrtPS
150 Kbps
100 Kbps
50 Kbps
Now System available Bw= 0
Start to BB operations at BS.
3
rtPS
300 Kbps
150 Kbps
150 Kbps
4
rtPS
200 Kbps
150 Kbps
50 Kbps
(1) Borrow from exiting BE
connections.
160 – 50 = 110 Kbps
(2) Borrow from exiting
nrtPS connections.
110 – 50 = 60 Kbps
(3) Borrow 45Kbps from CID3
Borrow 15Kbps from CID4
60 * 150/(150+50) = 45
60 * 50/(150+50) = 15
2008/07/25
After Bandwidth
Borrowing Operation
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
1
BE
50 Kbps
50 Kbps
0 Kbps
2
nrtPS
100 Kbps
100 Kbps
0 Kbps
3
rtPS
255 Kbps
150 Kbps
105 Kbps
4
rtPS
185 Kbps
150 Kbps
35 Kbps
Page 20
Example of Bandwidth Borrowing (BB)
BS
SS
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
Pairing UGS DSA
Total require 160Kbps(80x2)
1
BE
100 Kbps
50 Kbps
50 Kbps
2
nrtPS
150 Kbps
100 Kbps
50 Kbps
Now System available Bw= 0
Start to BB operations at BS.
3
rtPS
300 Kbps
150 Kbps
150 Kbps
4
rtPS
200 Kbps
150 Kbps
50 Kbps
(1) Borrow from exiting BE
connections.
160 – 50 = 110 Kbps
(2) Borrow from exiting
nrtPS connections.
110 – 50 = 60 Kbps
(3) Borrow 45Kbps from CID3
Borrow 15Kbps from CID4
60 * 150/(150+50) = 45
60 * 50/(150+50) = 15
BB Success !!!
Accept the Pairing UGS Call
2008/07/25
After Bandwidth
Borrowing Operation
Existing Connections in System
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
1
BE
50 Kbps
50 Kbps
0 Kbps
2
nrtPS
100 Kbps
100 Kbps
0 Kbps
3
rtPS
255 Kbps
150 Kbps
105 Kbps
4
5
rtPS
UGS
185 Kbps
80 Kbps
150 Kbps
80 Kbps
35 Kbps
0 Kbps
6
UGS
80 Kbps
80 Kbps
0
Page 21
Kbps
Two Stage Bandwidth Allocation
Stage One：
Allocate the guaranteed reserved bandwidth for each
existing connection at most.
min UL_Req+DL_Req , UL_Rsv+DL_Rsv
Stage Two: Allocate the remaining bandwidth
2008/07/25
First, satisfy all rtPS connections that require more
BW.
Final, allocate the remaining BW to nrtPS and BE
evenly.
Page 22
Collect all of
DL_BwReq and
UL_BwReq
Two Stage Bandwidth Allocation
In current frame
, the system can support
all of the DL_BwReq and
UL_BwReq?
Y
Grant every
received
BwReq directly.
N
Is there any
remaining bandwidth
?
Execute “Stage One”of
bandwidth allocation algorithm
N
Y
Is there any
remaining bandwidth
?
Share the remaining
bandwidth to every
Uplink connection
fairly.
N
Y
Execute“Stage Two”of
bandwidth allocation
algorithm
Downlink
Gather the grant
bandwidth
according to
different service
2008/07/25classes.
Downlink
or
Uplink?
Uplink
Gather the grant
bandwidth
according to each
SS.
Page 23
Outline
Background and Motivation
Proposed QoS System Architecture
Call Admission Control (CAC)
Pairing CAC
Bandwidth Borrowing on CAC level
Two Stage Bandwidth Allocation
Performance Evaluation
Conclusion and Future Work
2008/07/25
Page 24
Simulation Environment
Simulation Environment
Values
Number of BS
1
Number of SS
5 - 50
Traffic types generated by each SS UGS, rtPS, nrtPS, BE
Total Bandwidth
64 Mbps
Total Simulation Time
1000 Seconds
Frame Duration
10 ms
2008/07/25
Page 25
Traffic Generation and Simulation Environment
rtPS
Video Stream
DL：387Kbps
UL：38.7Kbps
DL：464.4Kbps
UL：46.44Kbps
DL：309.6Kbps
UL：30.96Kbps
FTP
DL：320Kbps
UL：32Kbps
DL：384Kbps
UL：38.4Kbps
DL：256Kbps
UL：25.6Kbps
Max Rate
Avg Rate
Min Rate
0
15 Seconds
Exponential
120 seconds
Exponential
37.5 Seconds
Exponential
240 seconds
Exponential
30 Seconds
Exponential
60 seconds
Exponential
10 Seconds
Exponential
20 seconds
Exponential
Maximum Latency
20 ms
50 ms
100 ms
Packet Size
160 Bytes 64-1518 Bytes
Fixed-Size Uniform
64-1518 Bytes
Uniform
400 ms
64-1518
Bytes
Uniform
Packet Inter Arrival
Time
20 ms
Fixed
Period
DL：20 ms
UL：200ms
Fixed Period
Application
Average Data Rate
UGS
VoIP
64 Kbps
Maximum Sustained
Traffic Rate
64 Kbps
Minimum Reserved
Traffic Rate
64 Kbps
Low Bound of
Reserved BW
Call Inter Arrival
Time
Call Duration
2008/07/25
DL : 16.35 ms
UL : 163.5ms
Fixed Period
nrtPS
BE
Email
192 Kbps
230.4Kbps
153.6Kbps
33ms
Fixed Period
Page 26
Simulation Experiment 1
Pairing
vs
NonPairing
Call Admission Control
2008/07/25
Page 27
Definition of NonPairing CAC
Reject Call
Non-Pairing CAC
First Type of Connection Fail
SS
BS
Non-Pairing CAC
Second Type of Connection Fail
SS
BS
Connection Request
(Uplink DSA)
es t
Requ
n
o
i
t
ec
Conn ink DSA)
(Upl
Re je c
Round Trip Time
of Downlink
Connection
Request
Accepted Provisionally
BS want to send a Connection Request
(Downlink DSA), but rejected by CAC !
t
Reject the previous accepted uplink
connection and release the reserved BW
(a)
2008/07/25
(b)
Page 28
Call Blocking Probability
Pairing vs NonPairing
I + II
UGS
Pair
I + II
rtPS
II
II
I
Pair
I
2008/07/25
Page 29
Call Blocking Probability
Pairing vs NonPairing
nrtPS
I + II
II
I + II
BE
Pair
II
I
Pair
I
2008/07/25
Page 30
Summary of Experiment 1
Pairing CAC is better than NonPairing CAC
Pairing CAC really achieves higher performance
than NonPairing CAC on call blocking probability.
What cause NonPairing CAC low performance?
The reply connection request is always rejected
leading to high blocking probability of NonPairing
Type II .
So the following next experiment will base on
Pairing CAC scheme to study Bandwidth
Borrowing scheme continually.
2008/07/25
Page 31
Simulation Experiment 2
Based on Pairing Call Admission Control
Bandwidth Borrowing
vs
Non Bandwidth Borrowing
2008/07/25
Page 32
Call Blocking Probability
Using Bandwidth Borrowing (BB)
Pairing CAC without BB
Pairing CAC with BB
rtPS
rtPS
2008/07/25
Page 33
Packet Drop Rate ─ Non BB vs BB
rtPS
nrtPS
2008/07/25
BE
Page 34
Conclusion
Proposed a novel QoS architecture over
WiMAX, including :
Pairing Call Admission Control (CAC)
Bandwidth Borrowing scheme on CAC level
Two Stage Bandwidth Allocation
Dynamic Downlink and Uplink bandwidth
allocation.
2008/07/25
Page 35
Future work
Different traffic pattern (self-similar traffic)
Extent to IEEE 802.16e mobility issue
(handover call, signal strength)
End to End QoS guarantee (ASN, CSN)
Heterogeneous Network (integrated with WiFi,
3G system, or EPON)
2008/07/25
Page 36
Q&A
Thanks for Your Attention
Worldwide Interoperability for
Microwave Access ( WiMAX )
Bandwidth
IEEE 802.15
IEEE 802.11
IEEE 802.16
3GPP
1 Gbps
100 Mbps
802.15.3
High Speed
Wireless
PAN
Wi-Fi
802.11n
WiMAX
802.16
(802.16-2004
& 802.16e)
10 Mbps
Wi-Fi
802.11a/b/g
1 Mbps
802.15.1
Bluetooth
<1m
10m
PAN
2008/07/25
4G
3G
2.5G
100m
Up to 50Km
LAN
Up to 80Km
MAN
PAN: Personal area networks
MAN: Metropolitan area networks
LAN: Local area networks
Wide area networks
WAN
Page 38
IEEE 802.16 Operation Mode
Point to MultiPoint (PMP) Mode
Mesh Mode (Optional)
Mesh SS
WiMAX
Backhaul
network
SS
BS
SS
Mesh SS
SS
Base Station (BS)
SS
Mesh SS
(a)
2008/07/25
(b)
Page 39
IEEE 802.16 d
Specify area
MAC layer
PHY layer
Topology of Operation Mode
PMP (Point to Multiple Point)
Mesh
Multiplex
2008/07/25
TDD
FDD
Page 40
Bandwidth Request
SSs may request bandwidth in 3 ways:
Contention-based bandwidth requests
(Broadcast Polling or Multicast Group Pollng)
Contention-free bandwidth requests (Unicast
Polling)
Piggyback a BW request message on a data
packet
2008/07/25
Page 41
Bandwidth Allocation
BS grants/allocates bandwidth in one of two
modes
Grant Per Subscriber Station (GPSS)
Grant Per Connection (GPC)
How much bandwidth to be granted based on
Requested BW
QoS parameters
Available resources
Grants are realized through the UL-MAP
2008/07/25
Page 42
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
2008/07/25
Page 43
Definition of Pairing and Non Pairing CAC
Pairing
Non Pairing
SS
BS
SS
BS
Uplink Connection Request
(Uplink DSA)
Bidirectional
Connection Request
(Uplink and Downlink DSA)
Accepted or Reject
Round Trip Time
of Downlink
Connection Request
Uplink Connection Request
(Uplink DSA)
Accepted Provisionally
BS send the Downlink
Connection Request
(Downlink DSA)
to SS after admitted by CAC
Uplink DSA Accepted Finally
2008/07/25
Page 44
Definition of NonPairing CAC
Accept Call
SS
BS
Round Trip Time:
The duration time
between admitting
Uplink Connection
Reqest and BS send
out the Downlink
Connection Request.
Uplink Connection Request
(Uplink DSA)
Round Trip Time
of Downlink
Connection Request
Uplink Connection Request
(Uplink DSA)
Accepted Provisionally
BS send the Downlink
Connection Request
(Downlink DSA)
to SS after admitted by CAC
Uplink DSA Accepted Finally
2008/07/25
Page 45
Operation of Bandwidth Borrowing (2)
If B borrow B C r e d i t
BE
the bandwidth borrowed from every exiting
BE connection i is：
( Rsv c u r r e n t Rsv low _ bound )
i
N BE
i 1
i
B borrow
( Rsv c u r r e n t Rsv low _ bound )
i
i
Else, try to borrow bandwidth from nrtPS
BE
after borrowing all bandwidth of B C r e d i t
2008/07/25
Page 46
Operation of Bandwidth Borrowing (3)
If B borrow B C r e d i t B C r e d i t
BE
n rtPS
the bandwidth borrowed from every exiting
nrtPS connection i is：
( Rsv c u r r e n t Rsv low _ bound )
i
N nrtPS
( Rsv
j 1
i
j
current
B borrow B C r e d i t
BE
Rsv low _ bound )
j
Else, try to borrow bandwidth from rtPS
n rtPS
after borrowing all bandwidth of B C r e d i t
2008/07/25
Page 47
Operation of Bandwidth Borrowing (4)
If
B
BC r e d i t BC r e d i t BC r e d i t
BE
borrow
n rtPS
rtPS
the bandwidth borrowed from every exiting rtPS
connection i is：
( Rsv c u r r e n t Rsv low _ bound )
i
N rtPS
k 1
i
B borrow B C r e d i t B C r e d i t
BE
n rtPS
( Rsv c u r r e n t Rsv low _ bound )
k
k
Else, Bandwidth Borrowing Fail !
Reject the connection request.
2008/07/25
Page 48
Mandatory Packet Scheduling Algorithm
Scheduling
Service
UGS
rtPS
nrtPS
BE
2008/07/25
Mandatory Algorithm
First In First Out (FIFO)
Earliest Deadline First (EDF)
Weighted Fair Queue (WFQ)
Round Robin (RR)
Page 49
System Model of Simulation Experiment
Note : We assume that only SS can send
the connection request to BS actively
SS-1 Local Network
BE
nrtPS
rtPS
SS-1
UGS
SS-2 Local Network
BE
nrtPS
rtPS
UGS
SS-N Local Network
BE
電腦
2008/07/25
nrtPS
電腦
rtPS
電腦
Up
link
Co
Do
nne
wn
ctio
link
n
Co
nne
SS-2
ctio
n
Uplink Connection
BS
WiMAX
Backhaul
Network
.
Downlink Connection
.
.
n
ctio
.
e
n
Con
.
k
tion
n
c
i
e
l
nn
SS-N Up
Co
k
lin
wn
o
D
UGS
電腦
Page 50
Traffic Generation and Simulation Environment
UGS
Application
rtPS
nrtPS
BE
VoIP
Video Stream
FTP
Email
64 Kbps
DL：387Kbps
UL：38.7Kbps
DL：320Kbps
UL：32Kbps
192 Kbps
64 Kbps
DL：464.4Kbps
UL：46.44Kbps
DL：384Kbps
UL：38.4Kbps
230.4Kbps
64 Kbps
DL：309.6Kbps
UL：30.96Kbps
DL：256Kbps
UL：25.6Kbps
153.6Kbps
Max Rate
64Kbps
(Max+Avg)/2
DL：425.7Kbps
UL：42.57Kbps
(Avg+Min)/2
DL：288Kbps
UL：28.8Kbps
Min / 2
76.8Kbps
Low Bound of
Guarantee Bw
Max Rate
Avg Rate
Min Rate
0
Call Inter Arrival
Time
15 Seconds
Exponential
37.5 Seconds
Exponential
30 Seconds
Exponential
10 Seconds
Exponential
Call Duration
120 seconds
Exponential
240 seconds
Exponential
60 seconds
Exponential
20 seconds
Exponential
Average Data Rate
Maximum
Sustained Traffic
Rate
Minimum Reserve
Traffic Rate
Accept Call
Criteria
2008/07/25
Page 51
Traffic Generation and Simulation Environment
UGS
Maximum
20 ms
Latency
Schedule Scheme FIFO
Packet Size
20 ms
Fixed
Period
Reserve Bw
Per frame
(Non Bandwidth 80 Bytes
Borrowing
Mode)
2008/07/25
nrtPS
BE
50 ms
100 ms
400 ms
EDF
WFQ
RR
160 Bytes 64-1518 Bytes
Fixed-Size Uniform
Packet Fragment 80 Bytes
Packet Inter
Arrival Time
rtPS
64-1518 Bytes 64-1518 Bytes
Uniform
Uniform
240 Bytes
120 Bytes
120 Bytes
DL : 16.35 ms
UL : 163.5ms
Fixed Period
DL：20 ms
UL：200ms
Fixed Period
33ms
Fixed Period
DL：532.125 B DL：360 B
UL：53.2125 B UL：36 B
96 Bytes
Page 52
Performance Metric
Call Blocking Probability :
UL Blocking Calls DL Blocking Calls
UL Total Calls DL ToTal Calls
Packet Drop Rate :
Total Dropped Packets
Total Generated Packets
2008/07/25
Page 53
Definition of Pairing CAC
SS
BS
Bidirectional
Connection Request
(Uplink and Downlink DSA)
Accepted or Reject
Accepted :
UL Total Calls ； DL Total Calls
Reject :
UL Total Calls ； UL Blocking Calls
Page 54
Master's Defense
2008/07/25
Definition of NonPairing CAC
Reject Call
Non-Pairing CAC
First Type of Connection Fail
SS
BS
Non-Pairing CAC
Second Type of Connection Fail
SS
BS
Connection Request
(Uplink DSA)
es t
Requ
n
o
i
t
ec
Conn ink DSA)
(Upl
Re je c
Round Trip Time
of Downlink
Connection
Request
Accepted Provisionally
BS want to send a Connection Request
(Downlink DSA), but rejected by CAC !
t
Reject the previous accepted uplink
connection and release the reserved BW
(a)
Page 55
Master's Defense
2008/07/25
(b)
Definition of NonPairing CAC
Default RTT of DL connection request
： 0.5 seconds
Accepted :
UL Total Calls ； DL Total Calls
First Type of Connection Fail :
UL Total Calls ； UL Blocking Calls
Second Type of Connection Fail :
UL Total Calls ；DL Total Calls
UL Blocking Calls ；DL Blocking Calls
Page 56
Master's Defense
2008/07/25
Where is the issue ?
Call Blocking Probability - Pairing and NonPairing
Non Pairing CAC without BB
2008/07/25
Pairing CAC without BB
Page 57
Call Blocking Probability
Non BB vs BB
UGS
2008/07/25
rtPS
Page 58
Call Blocking Probability
Non BB vs BB
nrtPS
2008/07/25
BE
Page 59
Outline
Introduction of IEEE802.16 and QoS
Proposed QoS System Architecture
Call Admission Control (CAC)
Pairing CAC
Bandwidth Borrowing on CAC level
Two Stage Bandwidth Allocation
Performance Evaluation
Conclusion and Future Work
2008/07/25
Page 60
Example of Bandwidth Borrowing (BB)
BS
SS
Pairing UGS DSA
Total require 160Kbps(80x2)
Now System avaible Bw= 0
Start to BB operations at BS.
System available Bw = 0
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
1
BE
100 Kbps
50 Kbps
50 Kbps
2
nrtPS
150 Kbps
100 Kbps
50 Kbps
3
rtPS
300 Kbps
150 Kbps
150 Kbps
4
rtPS
200 Kbps
150 Kbps
50 Kbps
(1) Borrow from exiting BE
connections.
160 – 50 = 110 Kbps
(2) Borrow from exiting
nrtPS connections.
110 – 50 = 60 Kbps
(3) Borrow 45Kbps from CID3
Borrow 15Kbps from CID4
60 * 150/(150+50) = 45
60 * 50/(150+50) = 15
BB Success !!!
Accept the Pairing UGS Call
2008/07/25
After Bandwidth
Borrowing Operation
System available Bw = 0
CID
Type
Reserved
BW
Low Bound of
Reserved Bw
Credit
1
BE
50 Kbps
50 Kbps
0 Kbps
2
nrtPS
100 Kbps
100 Kbps
0 Kbps
3
rtPS
255 Kbps
150 Kbps
105 Kbps
4
5
rtPS
UGS
185 Kbps
80 Kbps
150 Kbps
80 Kbps
35 Kbps
0 Kbps
6
UGS
80 Kbps
80 Kbps
0
Page 61
Kbps
Range of Bandwidth Reservation
Rsv-BE
0
Min/2
Rsv-BE
Low Bound
2008/07/25
Rsv-rtPS
Rsv-nrtPS
Min
Rate
(Average+Min)
/2
Rsv-nrtPS
Low Bound
Average
Rate
Rsv-UGS
(Peak+Average)
/2
Rsv-rtPS
Low Bound
Page 62
Peak
Rate
Call Blocking Probability
Pairing CAC vs NonPairing
2008/07/25
Page 63
NonPairing Call Blocking Probability (UGS)
Type I vs Type II
2008/07/25
Page 64
NonPairing Call Blocking Probability (rtPS)
Type I vs Type II
2008/07/25
Page 65
NonPairing Call Blocking Probability (nrtPS)
Type I vs Type II
2008/07/25
Page 66
NonPairing Call Blocking Probability (BE)
Type I vs Type II
2008/07/25
Page 67
Bandwidth Borrowing Schemes
Bandwidth Borrowing
Service Class
of
from the exiting connections in system
Connection Request
Scheme_1
Scheme_2
Scheme_3
UGS
BE nrtPS
BE nrtPS rtPS
BE nrtPS
rtPS
BE nrtPS
BE nrtPS rtPS
BE nrtPS
nrtPS
N/A
N/A
BE nrtPS
BE
N/A
N/A
N/A
2008/07/25
Page 68
Pairing Call Blocking Probability (UGS)
BB vs NonBB
2008/07/25
Page 69
Pairing Call Blocking Probability (rtPS)
BB vs NonBB
2008/07/25
Page 70
Pairing Call Blocking Probability (nrtPS)
BB vs NonBB
2008/07/25
Page 71
Pairing Call Blocking Probability (BE)
BB vs NonBB
2008/07/25
Page 72
Packet Drop Rate (rtPS)
BB vs NonBB
2008/07/25
Page 73
Packet Drop Rate (nrtPS)
BB vs NonBB
2008/07/25
Page 74
Packet Drop Rate (BE)
BB vs NonBB
2008/07/25
Page 75