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Quality of Service (QoS) Best Practicesfor CDMA2000 1xEV-DO Networks

Engineering Services Group QUALCOMM, Inc.

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Introduction to QoS

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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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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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How is QoS achieved?

QoS is achieved by optimal implementation of:• 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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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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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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Evolution of QoS in

CDMA2000 1xEV-DO Networks

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QoS in a typical 1xEV-DO Network Architecture

AT BTS RNC PDSN

Operator Core IP Data Network

Router 1 Router 3

Router 4

Router..n

Router 2

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Internet

1xEV-DO RAN

3GPP2 Framework

Air Interface QoS

Backhaul QoS(Typically IP over T1)

Backbone QoS(Typically IP over OC-3)

R-P Interface QoS(Typically IP over Ethernet)

Core Data Network QoS(Typically DiffServ mechanism)

QoS

Packet Marking and Classification

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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

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QoS in 1xEV-DO Rel 0 Networks: User-based

EXECUTIVE USER

STANDARD USER

Highest Priority Packets

Medium Priority Packets

Low Priority Packets

010011101010110010101100100010110100

010011101010110010101001010011101000101

PREMIUM USER01001110101011001010110011100

01001110010101101010101100101010

011001100111010101100101010

01001110101011001010101001010

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User-based QoS in 1xEV-DO Rel 0 Networks: Illustration

AT BTS RNC PDSN

Operator Core IP Data Network

Router 1 Router 3

Router 4

Router..n

Router 2

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Internet

1xEV-DO RAN

3GPP2 Framework

Air Interface QoS•User-based•Inter-AT QoS

Backhaul QoS•QoS for Abis signaling•QoS for different Users

Backbone QoS•Inherent application IP QoS•Dependency on AT marking IP QoS

R-P Interface QoS•QoS for A11 signaling •User Profile based QoS on A10

Core Data Network QoS(Typically DiffServ mechanism)

QoS

Packet Marking and Classification

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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:

1xEV-DO Rev A Air interface 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

1xEV-DO Rev A RAN features:

• 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

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Application-based QoS in 1xEV-DO Rev A Networks: Illustration

AT BTS RNC PDSN

Operator Core IP Data Network

Router 1 Router 3

Router 4

Router..n

Router 2

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Internet

1xEV-DO RAN

3GPP2 Framework

Air Interface QoS•QoS Negotiated•Application-based•Intra and Inter-AT

Backhaul QoS•QoS for Abis signaling•QoS for different Applications

Backbone QoS•Inherent application IP QoS•Rely on PDSN marking IP QoS

R-P Interface QoS•QoS for A11 signaling •Application Profile based QoS on Auxiliary A10

Core Data Network QoS(Typically DiffServ mechanism)

QoS

Packet Marking and Classification

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QoS Evolution in 1xEV-DO 3GPP2 Framework: SUMMARY

QoS Features 1xEV-DO Rel 0 1xEV-DO Rev A(Backward compatible to Rel 0)

1xEV-DO Rev B(Backward compatible to Rel 0 and Rev A)

Packet Classification • User-based (UATI-based)

• Multi-Flow (MFPA)• Enhanced Multi-flow (EMFPA)• Multi-Flow RTCMAC (Subtype 3)

• Multi-Link Multi-Flow (MLMFPA)

• Multi-Carrier Traffic Channels

Link Efficiency • FL Hybrid ARQ

• Short and Long PL Packets• Multi-User Packets• RL Hybrid ARQ• Packet-based framing• ROHC

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 Token-

bucket algorithm)

Admission Control• QoS Profiles and QoS Traffic

Class based

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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

• RLP header is applied

• RTCMAC subtype 3 assigns priorities to handle the data of each flow

MFPA or

EMPA

Stream Layer

MAC Layer

1xEV-DO Rev. A Application Layer

OSI Application Layer

Best Effort Flow

PSVT (SIP) Signaling

PSVT Audio user data (RTP)

RLP Flow 00

RLP Flow 01

Stream n (n is the 1, 2 or 3 negotiated

during session setup)

RTCMAC Flow 1

RTCMAC Flow 2

RLP Flow 02

RTCMAC Flow 3

PSVT Video user data (RTP)

RLP Flow 03

RTCMAC Flow 4

RTCMAC Flow 0

Stream 0

1xEV-DO Rev. A

Signaling Application

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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:• 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) Target Throughputb) Latency requirementsc) Jitterd) Reliabilitye) Access and Paging needsf) Flow and Filter Specification

3. Design for end-to-end QoS (within your control) for the application:a) Air Interfaceb) Backhaul between the BTS and RNCc) Backbone network between the RNC and PDSNd) Core network controlled by the operator.

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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:

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

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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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VT Application1xEV-DO Rev. A

StackAN

QoS Request for particular IP Flow

GAUP(ReservationKKQoSRequest)

Session Negotiation.All protocols negotiated to support QOS:· Multi-Flow Packet App· Subtype 3 RTCMAC· Enhanced FTCMAC· Subtype 2 Physical Layer

First time AT Powerup

VT App Invoked

Accept

Bring up PPP

PPP up notification

PPP negotiation

Idle state

GAUP(ReservationKKQoSResponse)

Accept

AT

RSVP RESV Message (Create TFT / Add filters to TFT)

RSVP CONFIRM Message

PDSN

SIP: REGISTER sent using default RLP

SIP: 401 Unauthorized

SIP: 200 OK

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REGISTRAR(SIP Server)

SIP: REGISTER

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GAUP (Optional Enhanced FTCMAC attributes)

Accept 20

PSVT Call Flow: QoS Setup (1 of 2)

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PSVT Call Flow: QoS Setup (2 of 2)B

undled in a single message

VT Application1xEV-DO Rev. A

StackAN

ATPDSN

Accept

GAUP (Negotiate RLP parameters)

GAUP (FlowNNIdentificationFwd/Rev to activate FLow NN)

GAUP (FlowNNReservationFwd/Rev to bind Flow NN to Resv KK)

QOS Granted

Accept (RLP parameters)

ReservationAccept

REGISTRAR(SIP Server)

Accept

GAUP (Negotiate RTCMAC3 Flow parameters)

Accept (RTCMAC3 Flow parameters)

GAUP (AssociatedFlowsNN binds RTCMAC3 Flow to RLP Flow)

Accept

GAUP (BucketLevelMaxNN non-zero value activates the MAC Flow)

Accept

ReservationONReq

Filters, Scheduler are set up so that appropriate filtering is done and packets

transmitted as per priority for QOS

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 PacketsA/V Data Packets A/V Data Packets A/V Data Packets

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ROHC Negotiation

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