Policy Control and LTE

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A Revolution in EvolutionPolicy Control and Mobile Broadbands Long-term Leap

A REvoluTIon In EvoluTIon

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A REvoluTIon In EvoluTIon

Table of ContentsExecutive Summary .....................................................................................4

Mobile Broadband and long-term Evolution ...............................................4

Policy and Charging Rules Function: Rules of order .....................................6

The Primacy of Policy ..................................................................................8

About Tekelec .............................................................................................9

4A REvoluTIon In EvoluTIon

Executive SummaryArmed with spectral efficiency, support for higher data rates and all-IP infrastructure, the

standards for the mobile broadband architecture known as long Term Evolution (lTE) are

arriving on the scene at just the right time. Coupled with policy approaches that allow

for intelligent management of network resources, lTE architectures offer tremendous

promise for solving a big problem confronting the industry: the current imbalance

between bandwidth demand and revenue generation. As lTE networks begin to be

deployed, the staging ground for a bold new era of mobile broadband is taking shape.

Mobile Broadband and Long-term EvolutionMobile broadband has clearly become the new growth engine in the mobile industry.

Carriers around the world are reporting large increases in revenue from data services,

driven in large part by mobile internet access, either through smartphones or via

personal computers. numerous mobile operators, especially in Europe, have begun

to offer subsidized netbooks small, low-cost laptop computers geared for internet

access bundled with a contract for mobile internet access. In many countries including

Austria, Germany, Ireland, the netherlands, Sweden, Finland and Portugal, contracts

for a 3GB+ mobile broadband service are lower than fixed line DSl services offered by

incumbents.1 Perhaps the best example of the impact of data growth on operators

revenue comes from vodafone Group, which reported organic revenue growth of 25%

for its data services for Q408 whereas the organic growth of voice and messaging

revenue remained flat. Clearly, mobile broadband will power the next phase of growth

for the mobile industry.

However, this growth does not come for free. For voice and messaging traffic,

bandwidth cost was well understood and relatively constant. The same is not true for

data. Different applications demand widely varying amounts of bandwidth. A text email

from a Blackberry may only consume 1 or 2 kilobytes (KB) of data with no stringent

concerns about latency. on the other hand, standard web pages often demand 500KB

of data or more, while video services can easily consume megabytes if not gigabytes

with latency a key quality concern. Despite the early stage of mobile broadband,

several operators have already crossed the threshold where their networks have more

data traffic than voice traffic.2 The result of this growing customer base and increased

bandwidth per user is that bandwidth capacity needs are growing much faster than

revenue. For example, Motorola projects 3G network operators in developed markets will

see 14 times (or higher) growth in bandwidth demand in 2009 while revenue grows only

up to 30%.

1. Analysys Mason, Sept. 2008

2. T-Mobile uK, 2008, Ericsson, 2008


Against this backdrop, products based on a set of standards called long Term Evolution,

or lTE, have recently arrived for an industry looking for help.

lTE was initiated in 2004 by the Third Generation Partnership Project (3GPP*) to define

a next-generation high speed radio access method. The main high level features of lTE-

based products are:

Support for higher speed data rates with theoretical downlink rates of up to 300 Mbps and uplink rates of up to 75 Mbps per 20Mhz of paired spectrum

Greater spectral efficiency to support larger numbers of customers for a given spectrum band at a lower cost per bit delivered

Flexible spectrum and deployment usage to allow lTE products to work in new and existing spectrum bands in a wide range of cell sizes

Reduced round trip and MAC state transition latency for faster response times

An all-IP network architecture

The first four feature areas deal primarily with improvements in the radio access network

technology, incorporating advances such as orthogonal frequency-division multiplexing

(oFDM), 64QAM modulation, more sophisticated error correction and multiple input/

multiple output (MIMo) and beam forming antennas. By achieving a 5x to 10x increase

in supported data rates and an estimated 70% lower cost3, suffice it to say the radio

engineers have achieved a remarkable set of advances.

The efforts to create an all-IP network were developed in 3GPP under the name Systems

Architecture Evolution (SAE), with the all-IP core network referred to as the Evolved

Packet Core (EPC). The goal was to enable use of more flexible and cost-effective IP

technology throughout the network, while at the same time providing a common core

network to enable application usage across 3GPP and non-3GPP (CDMA, DSl, cable,

etc.) access networks. This would facilitate multi-screen services, allow operators to

build and maintain one core network as well as more effectively utilize IP-based access

methods such as femtocells and dual mode devices to offload the macro radio network.

According to the Global Mobile Suppliers Association, 26 operators have committed to

deploy commercial lTE networks, 10 of which are planned for 2010 including launches

from verizon Wireless, TeliaSonera and nTT DoCoMo. Dittberner Associates projects the

number of lTE subscribers will grow from 3M in 2011 to over 1 billion by 2018.

3. nortel networks, 2007


Policy and Charging Rules Function: Rules of Order one of the key components of a 3GPP core network is a Policy and Charging Rules

Function (PCRF), which performs dynamic bearer and bandwidth control, charging rule

provisioning and in certain cases, lawful intercept control. The PCRF provides a single

place where the operator can implement business rules to dynamically control usage of

the network and how much to charge for particular services. For example, one common

use of the PCRF is to temporarily reduce bandwidth during peak hours for users that go

over their monthly usage quota in order to reduce the overall peak demand that drives

network capital expenditures. At the same time, the application specific control made

possible by the PCRF could also provide full bandwidth at a different charge for those

premium services that are paid for outside of the basic data service.

The PCRF was introduced in Release 5 of the 3GPP standards and has evolved as part of

Releases 6 and 7. The initiative within 3GPP that has been managing the PCRF related

issues is referred to Policy Control and Charging or PCC. In recent years, the PCRF has

become a regularly deployed element using DIAMETER-based interfaces to communicate

with applications (via the Rx interface) and the GGSn (via the Gx interface). To date, the

only access network expected is a home 3GPP-based network where the access gateway

is the operators own GGSn. With data roaming becoming much more common and

additional non-3GPP access networks expected, the fundamental change introduced

in Release 8 splits the PCRF into a home network element (H-PCRF) and visited

network element (v-PCRF) where the visited network may or may not be a 3GPP-based

mobile network.

Control PlaneData PlaneRoaming, FMC

3GPP Network,Home Network

Non-3GPP Network, Visited Network

Non-3GPP GW SGW

HSS

PCRF

PGW

ePDG

Figure 1: 3GPP Evolved Packet Core


The H-PCRF and v-PCRF communicate via a new DIAMETER-based interface called S9 in a

similar fashion to the way HlRs and vlRs communicate today. This function is sometimes

referred to as policy peering. There are three basic implementation options expected:

An implementation (Figure 2) where there are separate PCRFs for the home and visited networks and where all bits are routed back to and controlled by the home

network.

An alternative architecture where traffic is routed directly to the internet by the foreign network with home-based service control enabled by an H-PCRF.

A third non-roaming case where assuming the PCRF is capable of managing both 3GPP and non-3GPP access networks, there would be a single PCRF for any type of

local access network.

Non-3GPP Network,Visited Network

3GPP Network,Home Network

AF

V-PCRFS9

Rx

H-PCRFSp

SPR

Gxx Gx

BBERF PCEFGy

OSC

Gz

OFCS

Control PlaneRoaming, FMC Data Plane

Figure 2: 3GPP Release 8 PCC Architecture (Home Routed Access)

Another substantial change is that because the architecture expects non-3GPP access

networks, the access gateway will no longer always be a GGSn and as a result will have

different QoS and charging capabilities. Therefore, a generic non-3GPP access gateway

is defined as a Bearer Binding and Event Reporting Function (BBERF) controlled by

variants of Gx (such as Gxa, Gxb, Gxc, etc. referred to generically as Gxx) according to

the gateways capabilities. For example, non-3GPP gateways could include a Packet Data

Gateway (PDG), a CDMA PDSn, a cable CMTS or a telco B-RAS.


Release 8 PCC changes also include support for three additional features in recognition

that networks are becoming much more complex:

Support for mobile IP, in large part driven by the use of mobile IP to manage and control data services over foreign and non-3GPP access networks,

Management of mixed IPv4 and IPv6 environments,

Support for diameter routing agent (DRA) functionality, where a proxy or redirect agent acts as a central contact and routing point for DIAMETER sessions even if there are

multiple PCRFs in a network. In this way, applications, gateways and other PCRFs (e.g.

v-PCRF) dont have to know which PCRF to go to for a given session. The requests goes

to the topology aware DRA, which then routes the requests to the appropriate PCRF.

lastly, during implementations of Release 7 PCRFs for uMTS and HSPA networks,

participants have realized that several additional types of policy rules would be very useful:

Allocation and retention policies Policies that can implement prioritization of certain flows, including pre-emption capabilities and vulnerabilities

Aggregated maximum bit rate per APN Subscribed and authorized bandwidth maximums for an APn as a whole

Authorization of default bearer QoS The basic QoS parameters for the default best-effort data service flow. The importance of this function became especially evident

with the higher bandwidth of HSPA networks to create multiple bandwidth-based

service tiers. Given the very high bandwidth that can be achieved by lTE and the likely

multiple tiers of service that will be used, this function will continue to be very useful.

Time of day based rules Situations such as the activation and deactivation of rules based on time of day and time-based session revalidation. This is particularly useful as

operators have realized that session treatment should vary during peak and off peak

hours in order to maximum throughput while minimizing costly network congestion.

Credit related event reporting To allow operators to use Gx to manage QoS in response to quota related Gy events, certain Gy events such as final unit actions and

quota reallocation are reported over Gx. Again, the usefulness of this feature became

important in HSPA networks, and will become even more important with lTE.

The Primacy of Policy The EPC of Release 8 requires a PCRF for some obvious reasons and some not-so-

obvious reasons. The most obvious reason is that as services are implemented from

foreign and non-3GPP networks with widely varying QoS and cost metrics, a service

will perform and cost differently based on which network the user is located on. For

example, most femtocell and dual-mode services encourage use of the local network by

exempting any voice call minutes and data usage from the users quota. The payoff for

the operator is removing the traffic from the macro radio network. At the same time,

operators want to make sure the service works as well if not better than the same service

on the macro radio network moving on-net voice calls to voIP calls using an over the

top broadband connection will be unsuccessful if the calls lack clarity.


The not-so-obvious reason has been demonstrated by uMTS & HSPA networks, and will

continue to rise with the greater bandwidth of an lTE network. In pre-uMTS networks,

users could be provided as much bandwidth as the network could support because there

was so little bandwidth available to a single user. With data rates growing tremendously,

the use of multiple tiers of bandwidth and QoS is becoming much more common

either as a further point of differentiation for market segmentation, or to control

network abuse. looking at fixed-line networks that are capable of very high bandwidth

services shows what is likely to be in store for lTE networks just because the network

can deliver 30Mbps doesnt mean customers are going to get that level of service

automatically. FTTx and DoCSIS 3.0 networks are capable of delivering up to 100Mbps

at virtually the same cost as todays 5 to 10Mbps networks, but without government

incentives, the very high speed services generally cost 2x to 4x what basic service costs.

Examples of how multiple tiers of bandwidth are being used to monetize the increased

capacity of an HSPA network and will be used with lTE networks include:

offers for bandwidth-based tiers of default service (1Mbps for $X and 10Mbps for $2X)

Turbo type services that provide higher bandwidth temporarily for a fee or as a reward

Peak/off-peak or time-of-day-based services that provide higher bandwidth in off-peak hours

Abuse control mechanisms such as reducing over-quota users to a lower bandwidth level in peak hours

From prioritization policies to tiering, the coupling of lTE with policy controls

promises to help resolve key economic challenges of mobile broadband while supporting

a new generation of services that elevate revenue and delight customers. The work

of the 3GPP in devising new standards for mobile data networking will leave a

lasting imprint on the industry and expand the boundaries of the possible in mobile

communications worldwide.

About Tekelec Tekelec, the session and mobile data management company, enables billions of people

and devices to surf, talk, and text. our solutions allow service providers to dynamically

manage network resources and services, while providing end users with a consistent

and personalized customer experience. We handle the complexity of todays multi-

generational and multi-vendor networks by enabling devices, protocols, services, and

databases to securely and efficiently communicate with each other. Tekelec has more

than 30 offices around the world serving more than 300 customers in more than 100

countries. For more information, please visit www.tekelec.com.

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Policy Control and LTE

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