1 Radisys Corporation Confidential Welcome! 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/
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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
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Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
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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
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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
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Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
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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)
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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
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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
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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
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Today’s Agenda
Market Dynamics
LTE QoS Fundamentals
LTE QoS Methods and Mechanisms
Policy Enforcement
Conclusion
Q&A / Wrap-up
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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UE eNodeB MME Serving GW PDN GW PCRF
Call Flow - PCRF Interaction During Dedicated Bearer Setup