End-to-End QoS in LTE

1 Radisys Corporation Confidential

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April 12

Deploying LTE Small Cells: Interference

Mitigation Solutions

May 17

Building EPC Systems

June 14

The LTE Service Layer

July 12

End-to-End QoS in LTE

Real Implementation Challenges

of LTE Network Equipment:

Exploring the Trade-offs and

Solutions

To view past webinars:

http://www.radisys.com/recent-webinars/





End-to-End QoS in LTE Delivering the Appropriate Customer Experience

Speakers:

Larry Greenstein – Sr. Product Line Manager

Dikshit Sawhney – Software Architect

James Radley – Sr. Architect

July 12, 2012


Today’s Agenda

Market Dynamics

LTE QoS Fundamentals

LTE QoS Methods and Mechanisms

Policy Enforcement

Conclusion

Q&A / Wrap-up


End-to-End LTE Infrastructure From Radio Access to Media Processing

Evolved Packet Core Policy Control Radio Access Network IMS

Application

Server Media

Resource

Function

IP

Multimedia

Subsystem

Internet

Policy &

Charging

Routing

Function

Policy &

Charging

Enforcement

Function

Mobility

Management

Entity

LTE Security

Gateway

Serving

Gateway

Packet

Gateway

eNodeB

User

Equipment

Macro Small Cells

60+ Customer Wins

Audio Video Conf

~65% Market Share

10G 40G ATCA

~40% ATCA Market Share

Dumb Smart Pipes

Traffic Management

Home eNodeB

User

Equipment


Usage Up, Revenue Down QoS to the Rescue

Capacity Mind The Gap

Text

Traffic Doubling every 12 months

Video = Operators’ Albatross

Must Increase ARPU

Must Lower Cost per Bit

Source: Cisco VNI Source: Heavy Reading

Revenues

Traffic

Revenues &

Traffic Gap

Widening

Revenue vs. Traffic Growth

Voice Era

Data Era


Today’s Agenda

Market Dynamics



Policy Enforcement

Conclusion

Q&A / Wrap-up


LTE QoS: Fundamental Need

Why QoS?

• Finite network resources

– Radio spectrum limited

– Backhaul bandwidth limited

– Network congestion has to be managed

• Users (applications) need a variety of services

– Guaranteed bit rate (voice)

– High speed throughput (video)

– Priority service (emergency call)


Policy Control and Charging (PCC)

Policy Management

• Operator control over network usage

• Control the level of service provided and charge accordingly

– Superior performance for the customers that pay for it

– Enforce limits or restrictions based on customer subscription

– Dynamic service level adjustment enhances QoE

– Offer attractive options to gain market share

– Restrict content based on subscription or local laws


Where QoS Happens in the Network

Policy &

Charging

Rules

Function

Policy & Charging

Enforcement Function

Mobility

Management

Entity

Serving

Gateway

PDN

Gateway

eNodeB

Internet

Web

Email

Voice

UE

Radio

Bearer

S1

Bearer

S5

Bearer

Home

Subscriber

Server

Service

Data Flows

Packet

Filters

AF

Application

Function

IMS

Network


Poll Question 1

The top QoS concern of operators and equipment

manufacturers is:

A. Adding value and monetizing it (increase revenue)

B. Efficient use of network resources (reduce cost)

C. Ensuring customer satisfaction

D. Compliance with regulations


Today’s Agenda

Market Dynamics



Policy Enforcement

Conclusion

Q&A / Wrap-up


Agenda – QoS Specifics

QoS Functions in Control & User Plane

Policy & Charging Control Architecture

EPS Bearers and Service Data Flows

QoS Attributes

Example PCC Call Flow


QoS Functions

Control Plane

• Admission control maintains information about all available

resources of a network entity and takes decision to allow a

new session or not based on the current resource usage.

• Subscription Control checks whether or not a user is entitled

to use the requested service with the specified QoS attributes

• Service Management coordinates the functions of the control

plane entities during setup, modification and deletion of the

EPS bearers

• Translation function converts between the EPC QoS

parameters the various protocols for service control of

interfacing external networks e.g., UMTS to IP QoS parameters

mapping


QoS Functions

User Plane

• Mapping function provides each data unit with the specific

marking required to receive the intended QoS at the transfer

by a bearer service, e.g., DSCP marking at the PDN-GW

• Classification function assigns data units to the established

services of a user according to the related QoS attributes if

the user has multiple bearer services established

• Resource Manager distributes the available resources

between all services sharing the same resource based on the

QoS, e.g., scheduling, bandwidth management, and power

control for the radio bearers

• Traffic Shaping provides conformance between the

negotiated QoS for a service and the arriving data traffic


TE MT RAN CN EDGE Gateway Ext.

Netwk.

QoS Functions in different Network Elements

RAN Access Network

Service BB network service

Local BS Resource

Manager

Cond.

Class.

Resource

Manager

Cond.

Resource

Manager

Mapping

Resource

Manager

Mapping

Resource

Manager

Mapping

External BS

Cond.

Class.

RAN phys. BS


Policy and Charging Control (PCC) Architecture

Policy and Charging Rules

Function (PCRF)

Subscription

Profile

Repository

(SPR)

AF

Offline

Charging

System

(OFCS)

BBERF

Gateway

PCEF

Online

Charging

System (OCS)

Sp Rx

Gxx Gx

Gy

Gz


PCC Network Elements

PCRF (Policy & Charging Rules Function)

• PCRF is the central node in the policy and charging control architecture; it keeps a DB of PCC rules in SPR and supports flow-based charging and policy (QoS)

• Interworks with other network elements via the Diameter protocol

SPR (Subscription Profiles Repository)

• DB of PCC rules; can be co-located with HSS or PCRF

• A PCC rule consists of traffic filters to map Service Data Flows (SDF) to EPS Bearers, QoS and charging related parameters

PCEF (Policy & Charging Enforcement Function)

• The enforcement part of the policy architecture

• Main functions include DPI, traffic shaping, etc.

• Typically co-located with a PDN-GW

BBERF (Bearer Binding and Event Reporting Function) • Bearer Binding and Event Reporting Function

• Use PCC rules to map SDFs to EPS bearers; logical function of PDN-GW


Relationship between SDF Flows and EPS Bearers

QoS is defined on a per EPS Bearer basis

• An EPS bearer is an end-to-end connection between the

service user and PDN-GW. It consists of EPC Bearer, S1

Bearer and Radio Bearer

• Service data flows sharing the same QoS/IP address use the

same EPS bearer. Examples of SDFs include FTP, HTTP,

VoIP IMS traffic etc.

• Traffic filters at UE and PDN-GW determine which traffic flow

gets mapped to which EPS Bearer


EPS Bearers

GBR vs. Non-GBR Bearers

• GBR require resources to be reserved in every node in the

EPS through which data packet traverses; requires efficient

admission control methods

• Non-GBR specifies best-effort service – useful for

background, interactive traffic classes such as email, web

browsing, file download, etc.

Dedicated vs. Default Bearers

• Default bearer (one per UE IP) setup on Attach provides

basic connectivity – best effort QoS, non-GBR

• One or more Dedicated bearers setup for specific QoS

requirements – can be GBR or non-GBR


QoS Attributes

Maximum bit rate (MBR, AMBR)

• Maximum allowable bit rate for a GBR bearer or Aggregate

Maximum bit rate for all non-GBR bearers combined

• AMBR defined on per APN and per subscriber basis

Guaranteed bit rate (GBR)

• Guaranteed by the network via Admission Control

• Can’t exceed MBR in Release 8


QoS Attributes, continued

QoS Class Identifier (QCI)

• Defines packet forwarding treatment at each node, e.g.,

queuing thresholds, scheduling weight, admission control

priority, etc.

• Nine standardized QCI values with different characteristics –

GBR/non-GBR, priority, delay sensitivity, and packet error

loss rate e.g., QCI 1 is defined for a GBR bearer for

conversational or voice traffic

Allocation and Retention Priority (ARP)

• “Allocation” dictates control plane behavior during bearer

setup, modification procedures, etc.

• “Retention” determines relative priority of a bearer over

other bearers in case of congestion

• Fifteen different ARP (priority) levels – 1 being the highest

priority


UE eNodeB MME Serving GW PDN GW PCRF

Call Flow - PCRF Interaction During Dedicated Bearer Setup

(A)

(B)

1. IP-CAN Session Modification

2. Create Bearer Request

11. Create Bearer Response

12. IP-CAN Session Modification

3. Create Bearer Request

4. Bearer Setup Request / Session Management Request

5. RRC Connection Reconfiguration

7. Bearer Setup Response

8. Direct Transfer

6. RRC Connection Reconfiguration Complete

9. Session Management Response

10. Create Bearer Response


Today’s Agenda

Market Dynamics



Policy Enforcement

Conclusion

Q&A / Wrap-up


PCEF and DPI

The Policy & Charging Enforcement Function (PCEF)

cannot rely on coarse-grained assumptions about flow

types

• Subscriber to be identified and associated policy profile retrieved

• DPI of multiple initial packets in every new stream required to

correctly determine service signature

• Fragmented packets may need to be temporarily reassembled for

analysis before forwarding on in original pieces.

Policy engines need to be tailored to the unique

requirements for the confluence or regional usage

patterns and characteristics of installed network

• Enforce only those policies which matter and with no more

precision than necessary


User Specified Profiles

The win-win cost / benefit advantage of user-elected

usage profiles make this a compelling technology

My ideal profile may not be yours, e.g.:

• On-time delivery of VoIP packets above all else

• Anything over VPN should get preference over everything below

• Favor web browsing traffic

– But no need to hurry advertisements

• Don’t prejudice email traffic unless you must

• Feel free to throttle video (I don’t care) – unless I’m on Wi-Fi

• Please block software updates when I am roaming

– Particularly difficult: how does an operator export preference profiles?


Typical Flow Management Architecture

De-tunnel Extract flow ID Flow

Table

Known Flow Apply Rule

Application processing

- Load Balance

- Rate shaping

- Monitoring / Analysis

- Video conversion

- Policy enforcement

Unknown Classification Engine

Stateful, application aware, load balancer is key for traffic steering applications

Stage 1 Stage 2 Stage 3

Stage 4

Stage 5

~ 90% of packets

~ 10% of packets Update flow table

Update flow table

Custom

appln

Low

level

Assign new flow to

appropriate target

resource

Stage 6


Packet Flow Analysis

New packets arriving enable additional detail to be extracted from flow

HTTP GMAIL Metadata

…Username

…Email title

…Content

Apply Rule

Buffered

Packets

e.g. put into correct

priority queue

State Machine API

API Application adds

table entry & rule

Add new entry by default…

…or wait for application

Server Load

…approx 10% packets

User Application


Possible Mapping of LTE QCI: Single Subscriber

QC1

Voice

Flow Shaper

Commit/Excess/Red CIR

Com

mit

WF

Q

QC5

Signaling

Str

ict P

riority

Priority 1

Non

-CIR

WF

Q

Cla

ss S

ha

pe

r

Prio

rity

Ma

pp

er

QC2

Video

Flow Shaper

Commit/Excess/Red

QC3

Video

Flow Shaper

Commit/Excess/Red

QC4

Gaming

Flow Shaper

Commit/Excess/Red

CIR

Excess

WF

Q

QC6

Gaming

QC7 Video

QC8 TCP

Priority 2

Priority 4

Priority 3

<Commit

Green

<Excess

Yellow

>Excess

Red


Example: Traffic Management Assist

NPU mezzanine provides 80Gbps NPU for PP81 to

accelerate blade performance

Broad potential applications

• Load Balancing

• Ingress Traffic Management

• Egress Traffic Management

• IP Defragmentation

• Packet Normalization

• Statistics Acceleration

Efficient Software Interface for low overhead on XLP


Traffic Management Connectivity

RT

M

Broadcom

Trident switch

XLP832

XLP832

TM Mezzanine

PCIe x8 / ILA

4x10G

4x10G

Fab

ric

5 x 40G

(fabric ch0-4)

ICI

4 D

IMM

4 DIMM

120G

Up to 120Gbps

200G Fabric

Up to 5 ports

PCIe x8

8 x10G

PCIe x1

TM Unit

TM connects into main Ethernet switch to allow for flexible packet

routing configurations

TM managed over PCIe by XLP

Buffer

Memory

Stats

Memory


Traffic Management Key Features

Network processors can be used to add a number of

Traffic Management (TM) capabilities to a DPI blade:

• Egress traffic shaping with 256k queues and 5 levels of hierarchy

• Ingress packet filtering and denial-of-service prevention

• Flow-based load balancing across associated processors

• IP Defragmentation and packet reassembly

An NPU is designed to maintain the huge array of per-

Class of Service (CoS) queue counters and timers

required to provided fine-grained scheduling

• Weighted Round Robin (WRR)

• Deficit [Weighted] Round Robin (DRR / DWRR)

• Weighted Random Early Detection (WRED)

• Committed Information Rate / Committed Burst Size (CIR / CBS)


Poll Question 2

To adequately classify an LTE GTP-U packet stream

for QoS purposes, what degree of analysis is required?

A. QoS can be defined with a straight mapping based upon

assigned Tunnel Endpoint IDentifer (TEID)

B. Simple mapping from tunneled L3/L4 attributes (L4 port

number, DiffServ, Subscriber’s IP address, etc)

C. Parsing initial packets with a limited set of decision tree rules

to differentiate broad class of service (e-mail, video, http, etc.)

D. Signature analysis on early packets until a precise recognition

is made

E. Ongoing signature analysis in case the nature of the flow

changes

F. Can’t do any useful DPI because packets are encrypted


Today’s Agenda

Market Dynamics



Policy Enforcement

Conclusion

Q&A / Wrap-up


Unmatched Products & Expertise

Embedded

Wireless

Infrastructure

Solutions

Conclusions

LTE QoS Benefits

• User: Assures service delivery meets

expectations

• Operator: Can offer a wide variety of

services and monetize them

LTE QoS Challenges

• Requires coordination across all

business units to plan and execute

LTE QoS Opportunities

• LTE presents a tremendous

opportunity for mobile services to

grow faster than at any time in the

past

http://radisysbrandguide.findsubstance.com/downloads/Trillium_Mark_Master.zip


Today’s Agenda

Market Dynamics



Policy Enforcement

Conclusion

Q&A / Wrap-up


Q&A

Contact us!

Larry: [email protected]

DS: [email protected]

James: [email protected]

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End-to-End QoS in LTE