Transcript End-to-End QoS Provisioning in UMTS networks

End-to-End QoS Provisioning in UMTS networks
-Midterm Presentation
Group 995
Haibo Wang
Devendra Prasad
[email protected]
Supervisors:
Hans-Peter Schwefel
Oumer Teyeb
2005-2-22
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Presentation outline
1.
2.
3.
4.
5.
6.
Motivation
Background
Problem Delimitation
Preliminary Simulation
Proposed QoS algorithms
Future work
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1. Motivation
What is End2End QoS?
• Quality of Service
is a set of requirements to be met by the network while transporting
a traffic flow.
• Only the QoS perceived by end-user matters [1]
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End2End QoS Parameters
•
•
•
•
Delay
Jitter
Loss Rate
Throughput
These parameters reflect the traffic flow through the network.
QoS mechanisms
QoS provision mechanisms and QoS control mechanisms [2]:
• QoS provision mechanisms include parameters mapping, admission and
resource reservations schemes.
• QoS control mechanisms consist of traffic shaping, scheduling, policing and
control.
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Offered QoS through SLA
• QoS can be offered by network service provider in terms of Service Level
Agreement (SLAs)
i) Network Availability
ii) Guaranteed bit-rate
iii) Payment model
iv) Other legal necessities
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Why is QoS needed in UMTS?
UMTS Release 4
A main challenge for UMTS is
to convey various types of
traffics on the same medium
while meeting their different
QoS requirements, especially
for real-time applications.
UMTS Release 5
Note: UMTS core
networks evolution to all
IP backbone.
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2. Background
The E2E UMTS QoS case we are investigating
Application
Servers
UEs
UTRAN
SGSN
GGSN
Internet
Two domain involved form end-2-End QoS point of view:
UMTS domain QoS and IP domain QoS
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2.1 UMTS QoS Domain:
End2End QoS Architecture
UMTS
TE
MT
RAN
CN
Gateway
CN
EDGE
NODE
TE
End-to-End Service
TE/MT Local
Bearer Service
External Bearer
Service
UMTS Bearer Service
Radio Access Bearer Service
Radio Bearer
Service
Physical Radio
Bearer Service
RAN Access
Bearer Service
CN Bearer
Service
Backbone
Bearer Service
Physical
Bearer Service
• 3GPP layered structure [1]
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UMTS QoS - UMTS QoS classes
Traffic class
Fundamental
characteristics
Conversational
class
conversational RT
Streaming class
streaming RT
Interactive class
Interactive best
effort
Background
Background
best effort
-Preserve time
relation (variation)
between information
entities of the
stream
-Preserve time
relation (variation)
between
information entities
of the stream
-Request response
pattern
-Preserve payload
content
-Destination is
not expecting
the data within
a certain time
-Preserve
payload
content
Conversational
pattern (stringent
and low delay )
Example of the
application
-voice
-streaming video
-Web browsing
-background
download of
emails
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UMTS QoS provisioning
• Existing UMTS QoS mechanisms:
- QoS profile
- Traffic Flow Template (TFT)
- PDP context
• What is missing in 3GPP standardization?
- UTRAN part: QoS parameters mapping to Radio Resource
Management strategies
- UMTS core network part: IP layer transport mechanisms on the Gn
and Gi interface
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2.2 IP QoS
DiffServ and InterServ comparison
Integrated services
Differentiated services
State in routers (e.g., scheduling
buffer management)
Per-flow
Per- Aggregate
Traffic classification basis
Several header fields
The DS field (6 bits) of the
IP header
Admission control
Required
Required for absolute
differentiation only
Signaling protocol
Required (RSVP)
Not required for relative
schemes; absolute schemes
need semi-static
reservations or broker
agents
Coordination for service
differentiation
End-to-end Local
(per-hop)
Scalability
Limited by the number
of flows
Limited by the number of
classes of service
Network management
Similar to circuitswitched networks
Similar to existing IP
networks
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3. Problem Delimitation
UE
Local
UE
GGSN
Remote
AP
Remote
Host
Remote
Host
IP Bearer Service
GGSN
Backbone IP
Network
Remote
Access
Point
SGSN
Gn/Gp
IP Bearer
Layer
Access
Bearer
Layer
(eg. UMTS
Bearer)
Scope of PDP Context
Network Architecture for QoS Conceptual Models
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Problem Statement
1. External IP network: IETF standard QoS mechanism – DiffServ or InterServ
2. UMTS network domain:
1) QoS classes mapping between External IP QoS classes and UMTS QoS classes, and
UMTS Bear Service (BS) attributes mapping to Core Network (CN) BS and Radio
Access Bearer (RAB) and further to Radio BS and Iu BS.
2) Call Admission Control in every multiplexing point (GGSN, SGSN, etc)
3) GGSN policing: check downlink flow and filter it according to TFT
4) Scheduling and congestion mechanisms in CN transmission (I,e, WFQ, WRED, etc)
5) QoS differentiation implementation in RRM
3) Other open issues: Application level End2End QoS provisioning, i.e, SIP signalling
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State of the Arts
1.
Advanced Radio Resource Management for Wireless Services(ARROW) :
www.arrow-ist.es
This project aims at providing advanced Radio Resource Management
(RRM) and Quality of Service (QoS) management solutions, for both
UTRA-TDD and UTRA-FDD modes. It includes packet access,
Asymmetrical traffic and high bit rate (2 Mbit/s) services for multimedia IP
based applications.
Although ARROWS concentrates on the QoS aspects of UTRAN, a
global QoS framework is proposed, which is relevant with our work.
2.
Advanced Services by Mastering UMTS (SAMU) : www.samu.crmparis.com
The innovative work in QoS from SAMU includes UMTS/IP QoS mapping
architecture and UMTS link layer optimization for TCP. The architecture
includes both mapping between IP DiffServ and UMTS bearer and mapping
from UMTS bearer to lower layer.
We refer to the mapping between IP DiffServ and UMTS Bearer from this
project.
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3.
Simulation of Enhanced UMTS Access and Core Networks (SEACORN) :
www.seacorn.ptinovacao.pt
Development, and implementation of resource management algorithms enabling
QoS provisioning and differentiation while optimizing resource efficiency
This project contribute a system level UMTS network simulator based on NS-2,
named Enhanced UMTS Radio Access Network Extensions (EURANE), which
We chose as the base of our simulator.
•
Contributions and drawbacks of these related works:
a). Many E2E QoS frameworks were proposed but solid implementation and
simulation output are still missing.
b). QoS attributes mapping are designed but not implemented.
c). These work more focused on the RRM implementation, no core network QoS
mechanisms are considered.
d). None of the framework gives a clear picture about the impact of mixing real-time
and non-realtime traffics on the QoS aspects.
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Problem Delimitation
• Traffic: Mixed types of user data (real-time and non-real-time) flow from
external application servers to UMTS User Equipments (UEs). And we only
focus on downlink traffic flow.
• For Internet/External network QoS -> IETF DiffServ approach was chosen.
Reason: more scalable and easy to manage when more than one network
operator involved.
• In UMTS Core Network side:
1) Mapping mechanism from DiffServ QoS classes to UMTS QoS classes in
GGSN
2) Call Admission Control in GGSN considering required QoS profile and
available equivalent bandwidth
3) Scheduling and queuing mechanisms to differentiate different UEs
according to their UMTS service classes (Conversational, Streaming,
Interactive, Background)
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Simulation Tool – Network Simulator
version 2 (NS-2) and its UMTS extension
•No PDP Context Functionality.
•SGSN and GGSN are “Routers” from standard
NS-2.
•DiffServ functionalities are available
•Some buffer management algorithms are available
for congestion control, i.e. Random Early Discard
(RED)
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4. Preliminary Simulation
Simulation Scenarios:
1. Network Topology
Appl. Server1
UE1
2Mb
10Mb
2Mb
10Mb
10Mb
1Mb
10Mb
UE2
Node B
RNC
SGSN
GGSN
Appl. Server2
10Mb
2Mb
UE3
Appl. Server3
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2. Traffic Model
•
Constant Bit Rate (CBR) source for real-time applications
•
Exponential traffic source for non-realtime applications
•
All traffic is working on UDP protocol
3. Mobility Model
none
4. Propagation Model
Ideal,
Standard NS-2 error model to be set in future
5. QoS mechanism
Best Effort
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Simulation Result 1
User throughput when the total traffic load is lower then the
bandwidth in Core network (SGSN-GGSN)
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Simulation Result 2
Slightly overload
Heavily overload
User throughput when the total traffic load is higher then the
bandwidth in Core network (SGSN-GGSN)
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Conclusion
In case of Best Effort transmission, the real-time traffics will
suffered from the mixing with non-realtime
Traffics in case of network congestion.
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5. Proposed End2End QoS algorithms
PDP Context generation through event based
UE1
Database (At the time of event
Generator and use it for CAC
DS 1
Core Router
SGSN
UE1
UE2
GGSN
Edge Router
CAC
Mapping
UE3
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PDP Context generation through event based
•Event based PDP generation,
•Acknowledgement based database for PDP Context
•Event based Traffic generation,
•1,2,3,4 is Available Bandwidth and 6 is an acknowledgement
Database: UE id,APN,BW Available,
2
1
UE
Node B
RNC
3
4
SGSN
5
GGSN
6
AS
Duration : 50ms
Acknowledgement
Duration : 55ms
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Total Duration : 60ms
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Mapping
•UMTS QoS Attributes are Guaranteed Bit Rate and SDU size.
•IP QoS Attributes are burst size and arrival rate stored in traffic
profile of the SLA. [2]
•Differentiated Services considered.
•IPv4 header field TOS is used for DSCP.
•Assured Forwarding is considered for the traffic class buffering.
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Mapping
-continue
•Assumptions are IPv4, AF for PHB
Core Router: PHB
Scheduling,Buffering
Traffic Profile:
Burst Size,
Arrival Rtes
DS1
GGSN
Guaranteed Bit rate, SDU Size
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Call Admission Control
database
2
SGSN
4
3
GGSN
External Net
1
ER
1. Incoming Traffic class,
2. Check with the Database for the Resource reservation,
3. Set priority based on the Available BW and Traffic class,
I.e Real-time: High priority, Non Real-time: Low Priority,
4. Scheduling, policy setting
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Conclusion
•The most of technical paper or EU funded project proposed the the concept
but none with the E2E aspect.
•As the emphasis is on the Multimedia Services , Hence the mapping
between the UMTS and the IP Network is the highest priority.
•The proposed algorithm will offset the limitation of an available simulator
with the implementation of Event based PDP Context and traffic generation.
•The purpose of the proposed topology is to design the algorithm which deals
the End to End QoS aspect including mapping,Scheduling and resource
reservation.
•The proposed algorithm will reduce the end2end delay and packet loss
probability
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Future Work
•Implementation of proposed topology and validation of proposed
algorithm.
•To show that the mix of non real time application makes the real
time application to suffer.
•To show the proposed queuing and scheduling technique will
improve the real time application When it mix with non real time
application.
•To show the Guaranteed bit rate per user can be achieved even
during the congestion .
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References
[1] 3GPP TS23.107
[2] SAMU project, QOS Deliverable SP2-D1,
http://samu.crm-paris.com/, 2001.
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Backup
Proposed Mapping in ASMU project [2]
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