Transcript Document

Quality of Service (QoS) Best Practices
for CDMA2000 1xEV-DO Networks
Engineering Services Group
QUALCOMM, Inc.
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Introduction to QoS
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Q U A L C O M M
C O N F I D E N T I A L
What is QoS?
QoS is a practice, that refers to the capability of a network to provide:
• Differentiated service to a selected group of user applications or for
specific types of network traffic over
- Various transport technologies and across all communication segments
QoS allows users with different OSI application layer needs to meet
their service requirements while utilizing the available network
resources efficiently
QoS is IP data networking done right, to ensure consistent good user
experience
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Q U A L C O M M
C O N F I D E N T I A L
Why implement QoS?
Implementing QoS in IP networks:
• Ensures a consistent good user experience
• Enables new differentiated services and classes of service that were
previously not feasible
• Supports tailored services for operator differentiation
• Allows coexistence of business-critical applications alongside interactive
multimedia and voice applications
• Provides more efficient resource control and usage
• Is the foundation of the fully integrated network of the future
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Q U A L C O M M
C O N F I D E N T I A L
How is QoS achieved?
QoS is achieved by optimal implementation of:
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Packet Classification
Link Efficiency
Queue Management
Congestion Management
Traffic Shaping and Policing
Admission Control
Every communication segment and network elements across all these
communication segments must perform their share of QoS function
• Air interface, backhaul and IP backbone are few examples
communication segments
• BTS, RAN, PDSN and Routers are few examples of network elements
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Q U A L C O M M
C O N F I D E N T I A L
QoS Application Criteria
The four horsemen of an QoS applications are:
• Target Throughput (kbps): The minimum data rate at which usable
data can be sent over the communication path from the origination to the
destination
• Delay/Latency (ms): Maximum allowable delay between sending a
packet at the origination and reception of that packet at the destination
• Jitter: The statistically tolerable variance of inter-arrival delay between
two consecutive packets within the same IP flow/stream
• Reliability/PER (%): The number of packets that are in error out of the
total number of packets transmitted
The mechanism to honor the above per application requirements
is Quality of Service (QoS)
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C O N F I D E N T I A L
Examples of QoS Applications
Applications with flows that require QoS treatment are:
• Voice over IP (VoIP)
- Full-duplex communication with two flows: control and speech
• Packet Switched Video Telephony (PSVT)
- Full-duplex communication with three flows: control, audio and video
• Video Streaming (VS)
- Half-duplex communication with three flows: control, audio and video
• Push to Talk (PTT)
- Half-duplex communication with two flows: control and audio
- Rapid connection and paging
• Low Latency Games
- Full-duplex communication with one flow: control
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Q U A L C O M M
C O N F I D E N T I A L
Evolution of QoS in
CDMA2000 1xEV-DO Networks
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Q U A L C O M M
C O N F I D E N T I A L
QoS in a typical 1xEV-DO Network Architecture
3GPP2 Framework
1xEV-DO RAN
Router 1
Operator Gateway
and Firewall
Operator Core IP
Data Network
Router 3
Router..n
AT
BTS
RNC
PDSN
Router 2
Router 4
Core Data Network QoS
(Typically DiffServ mechanism)
Air Interface
QoS
R-P Interface QoS
(Typically IP over Ethernet)
Backhaul QoS
(Typically IP over T1)
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Q U A L C O M M
Backbone QoS
(Typically IP over OC-3)
C O N F I D E N T I A L
Packet Marking
and Classification
Internet
QoS
QoS in 1xEV-DO Rel 0 Networks: User-based
User-based QoS in 1xEV-DO Rel 0 systems:
• Enables the system to treat users with different levels of priority based
on their subscription level (Executive, Premium, Standard)
 User profile determines priority level and available applications
 Different levels of priority based on the current application utilized
 Flexibility to switch priorities based on the applications launched
• Once priority established, all of the user’s application packets are
treated with same priority
• Implemented with minimal software changes
Highest Priority Packets
Medium Priority Packets
Low Priority Packets
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Q U A L C O M M
C O N F I D E N T I A L
010011101010110010101100100010110100
EXECUTIVE USER
010011101010110010101001010011101000101
01001110101011001010110011100
PREMIUM USER
01001110010101101010101100101010
011001100111010101100101010
STANDARD USER
01001110101011001010101001010
User-based QoS in 1xEV-DO Rel 0 Networks: Illustration
3GPP2 Framework
1xEV-DO RAN
Router 1
Operator Gateway
and Firewall
Operator Core IP
Data Network
Router 3
Router..n
AT
BTS
RNC
PDSN
Router 2
Router 4
Core Data Network QoS
(Typically DiffServ mechanism)
Air Interface QoS
• User-based
• Inter-AT QoS
R-P Interface QoS
• QoS for A11 signaling
• User Profile based QoS on A10
Backhaul QoS
• QoS for Abis signaling
• QoS for different Users
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Backbone QoS
• Inherent application IP QoS
• Dependency on AT marking IP QoS
C O N F I D E N T I A L
Packet Marking
and Classification
Internet
QoS
QoS in 1xEV-DO Rev A: Application-based
Application-based QoS in 1xEV-DO Rev A systems:
• Enables the system to treat applications with different levels of priority
 Same applications within and across ATs get the same priority.
• Implemented with an upgrade to 1xEV-DO Rev A system that provides:
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1xEV-DO Rev A Air interface features:
1xEV-DO Rev A RAN features:
• Multi-Flow Packet Application and Enhanced
Multi-flow Packet Application
- Packet-based RLP
- ROHC
• Short Packets
• Multi-user Packets
• One-to-many mapping of DRC index to
transmission formats
• NULL to non-NULL Rate DRC mapping
• DRC Translation Offset
• RTCMAC Subtype 3 algorithm
• RL Hybrid ARQ
• Data Source Control channel
• Improved Access Channel for rapid access
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QoS aware scheduler
DRC/DSC Erasure mapping
FL Delayed-ARQ
Seamless handoff via Route Selection
Sub-Synchronous Control Channel Cycle for fast
paging
• Quick Connect
1xEV-DO Rev A PDSN features:
• SO67 to forward IP packets to RAN
• Packet filters & prioritization with Multiple A10’s
• Authorization & accounting
Application-based QoS in 1xEV-DO Rev A Networks: Illustration
3GPP2 Framework
1xEV-DO RAN
Router 1
Operator Gateway
and Firewall
Operator Core IP
Data Network
Router 3
Router..n
AT
BTS
RNC
PDSN
Router 2
Router 4
Core Data Network QoS
(Typically DiffServ mechanism)
Air Interface QoS
• QoS Negotiated
• Application-based
• Intra and Inter-AT
R-P Interface QoS
•QoS for A11 signaling
•Application Profile based QoS
on Auxiliary A10
Backhaul QoS
• QoS for Abis signaling
• QoS for different Applications
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Backbone QoS
• Inherent application IP QoS
• Rely on PDSN marking IP QoS
C O N F I D E N T I A L
Packet Marking
and Classification
Internet
QoS
QoS Evolution in 1xEV-DO 3GPP2 Framework: SUMMARY
QoS Features
1xEV-DO Rel 0
1xEV-DO Rev B
(Backward compatible to Rel 0)
(Backward compatible to Rel 0 and Rev A)
• User-based (UATI-based)
• Multi-Flow (MFPA)
• Enhanced Multi-flow (EMFPA)
• Multi-Flow RTCMAC
(Subtype 3)
Link Efficiency
• FL Hybrid ARQ
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Queue Management
• User-based Priority (Inter-AT)
• FL Proportional Fair Scheduler
• RL Rate Transition
Probabilities
• Applications-based Priority
(Inter-AT and Intra-AT)
• FL Generalized/Delay Fair
• RL RTCMAC algorithm
(Transition\Priority Functions)
• Multi-Carrier Independent
Queuing
Congestion
Management
• Flow Control
• RED, WRED and Tail Drop
mechanisms
• FL D-ARQ, DRC/DSC Erasure,
NULL to non-NULL Rate map
• RL RTCMAC algorithm
• Enhanced Flow Control
• Multi-Carrier Load Balancing
Traffic Shaping and
Policing
• @ PDSN
• User-based Profile
• Application-based Profile
(FL Scheduler and RL Tokenbucket algorithm)
Packet Classification
Admission Control
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1xEV-DO Rev A
Q U A L C O M M
C O N F I D E N T I A L
• Multi-Link Multi-Flow
(MLMFPA)
• Multi-Carrier Traffic Channels
Short and Long PL Packets
Multi-User Packets
RL Hybrid ARQ
Packet-based framing
ROHC
• QoS Profiles and QoS Traffic
Class based
QoS in 1xEV-DO Rev A
Networks
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QoS Within a 1xEV-DO Rev A Framework
The QoS required for an application with distinct IP Flows (such as
PSVT Audio, PSVT Video and Signaling IP Flow) is achieved using:
• Multi-Flow Packet Application (MFPA) or
Enhanced Multi-Flow Packet Application (EMFPA)
• Reverse Traffic Channel MAC Subtype 3 protocol (RTCMAC3) on the
Reverse Link
• Enhanced Forward Traffic Channel MAC Protocol on the Forward Link
• Physical Layer Subtype 2
• QoS aware Forward Link Scheduler
Various attributes of the protocols are negotiated either using the
Session Configuration Protocol or the Generic Attribute Update
Protocol.
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What does QoS mean in 1xEV-DO Rev A Networks?
Flows, Flows, Flows, and Queues
To achieve 1xEV-DO Rev A air interface QoS for an application, the
following flows are used and negotiated:
• IP Flows are data streams generated by a user application (OSI) residing
outside the 1xEV-DO Rev A protocol stack.
• RLP Flows reside at the 1xEV-DO Rev A Application Layer and use
either Multi-Flow Packet Application (MFPA) or Enhanced MFPA. These
flows are mapped to the upper layer IP flows.
• RTCMAC Flows reside at the 1xEV-DO Rev A MAC layer and use
RTCMAC Subtype 3. These flows are associated to the upper layer RLP
flows.
Multiple instances (queues) of these flows provide QoS for concurrent
applications at the AT, such as PSVT Audio, PSVT Video, and PSVT signaling.
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Multi-Flow Concept: Concurrent BE and PSVT Traffic
• Each flow has independent
QoS requirement –
Identified by a Reservation
Label
• Association between
Reservation Label and
RLP Flow is established
Best Effort
Flow
PSVT (SIP)
Signaling
PSVT
Video user
data (RTP)
OSI
Application
Layer
RLP Flow
02
RLP Flow
03
1xEV-DO Rev. A
Application
Layer
MFPA
or
EMPA
1xEV-DO Rev. A
Signaling
Application
PSVT
Audio user
data (RTP)
RLP Flow
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RLP Flow
01
• RLP header is applied
Stream n
Stream 0
• RTCMAC subtype 3
assigns priorities to handle
the data of each flow
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Q U A L C O M M
RTCMAC
Flow 0
C O N F I D E N T I A L
Stream
Layer
(n is the 1, 2 or 3 negotiated
during session setup)
RTCMAC
Flow 1
RTCMAC
Flow 2
RTCMAC
Flow 3
RTCMAC
Flow 4
MAC
Layer
How is QoS requested in 1xEV-DO Rev A Networks?
QoS in 1xEV-DO Rev A is defined and requested in terms of:
• Flow Specification – Used by the AT to state air interface resources
required for QoS application (FlowProfileID)
 Interaction between AT and RAN over 1xEV-DO Rev A Signaling
• Filter Specification – Used by the AT to define IP traffic flow classification
and QoS treatment determination (Traffic Flow Template or TFT)
 Interaction between AT and PDSN as Reservation Resource Protocol (RSVP)
over UDP Port 3455
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Successful QoS Configuration
The conditions for QoS to be GRANTED are:
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AT requests QoS (as a reservation, one per IP QoS Flow)
QoS request accepted by AN with a non-NULL QoS response
Requested reservation mapped to an RLP flow
RLP to which the reservation is mapped is activated
RLP flow is associated with an RTCMAC flow
RTCMAC flow is activated
RSVP messaging with the PDSN is successful, with the TFTs
appropriately configured
At this point QoS is Ready
The AT, having determined the air interface QoS profile and the PDSN
QoS configuration are complete, sends a ReservationOnRequest
message when it desires to use the QoS
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Logical States of QoS in 1xEV-DO Rev A Networks
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QoS Best Practices
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QoS Best Practices for 1xEV-DO Rev A Networks
1. Establish AT’s protocols and OSI application capabilities
2. Understand the QoS application’s needs:
a)
b)
c)
d)
e)
f)
Target Throughput
Latency requirements
Jitter
Reliability
Access and Paging needs
Flow and Filter Specification
3. Design for end-to-end QoS (within your control) for the application:
a)
b)
c)
d)
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Air Interface
Backhaul between the BTS and RNC
Backbone network between the RNC and PDSN
Core network controlled by the operator.
Q U A L C O M M
C O N F I D E N T I A L
QoS Best Practices for 1xEV-DO Rev A Networks
4. End-to-end application QoS design considerations:
a)
Coexistence with other QoS application
b)
Coverage
c)
Capacity dimensioning (access and paging load considerations)
5. When to setup air interface QoS:
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a)
Always-On QoS application, such as VoIP: Negotiate 1xEV-DO Rev A
air interface QoS as part of Session Negotiation
b)
On-Demand QoS application, such as Video Streaming: Negotiate
1xEV-DO Rev A air interface QoS only when QoS application is
invoked
Q U A L C O M M
C O N F I D E N T I A L
QoS Best Practices for 1xEV-DO Rev A Networks
6. QoS setup signaling optimizations:
a)
Air Interface QoS signaling with RAN and RSVP messaging with the
PDSN should happen in parallel
b)
Application registration (such as SIP REGISTER) can happen in
parallel with QoS setup
7. Maintain QoS setup signaling integrity:
a)
All reservations for a single application (such as PSVT audio, PSVT
video and signaling) should be bundled in a single QoS request
message
b)
Protocol specific attributes negotiated should be bundled in a single
bundled message
8. Implement Admission Control mechanisms
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Backup Slides
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PSVT Call Flow: QoS Setup (1 of 2)
AT
VT Application
1
AN
1xEV-DO Rev. A
Stack
First time AT Powerup
PDSN REGISTRAR
(SIP Server)
Session Negotiation.
All protocols negotiated to
support QOS:
·
Multi-Flow Packet App
·
Subtype 3 RTCMAC
·
Enhanced FTCMAC
·
Subtype 2 Physical Layer
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3
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Idle state
VT App
Invoked
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Bring up PPP
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PPP up notification
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9
PPP negotiation
QoS Request for
particular IP Flow
SIP: REGISTER sent
using default RLP
GAUP
(ReservationKKQoSRequest)
Accept
SIP:
401 Unauthorized
RSVP RESV Message
(Create TFT / Add filters to TFT)
GAUP
(ReservationKKQoSResponse)
Accept
RSVP CONFIRM Message
SIP: REGISTER
SIP: 200 OK
GAUP (Optional Enhanced
FTCMAC attributes)
Accept
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PSVT Call Flow: QoS Setup (2 of 2)
AT
VT Application
AN
1xEV-DO Rev. A
Stack
PDSN
REGISTRAR
(SIP Server)
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Accept
GAUP
(Negotiate RLP parameters)
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Accept (RLP parameters)
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GAUP (FlowNNReservationFwd/Rev
to bind Flow NN to Resv KK)
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Accept
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GAUP (BucketLevelMaxNN non-zero
value activates the MAC Flow)
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Accept
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GAUP (Negotiate
RTCMAC3 Flow parameters)
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Accept (RTCMAC3 Flow parameters)
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GAUP (AssociatedFlowsNN binds
RTCMAC3 Flow to RLP Flow)
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Accept
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ROHC Negotiation
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ReservationONReq
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ReservationAccept
Filters, Scheduler are set up so that
appropriate filtering is done and packets
transmitted as per priority for QOS
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QOS Granted
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Filters, Scheduler, A10 connections are set
up so that appropriate filtering is done and
packets transmitted as per priority for QOS
VT App is
ready to
send data
A/V Data Packets
C O N F I D E N T I A L
A/V Data Packets
A/V Data Packets
A/V Data Packets
Bundled in a single message
GAUP (FlowNNIdentificationFwd/Rev
to activate FLow NN)