Generic Policy Control for Local Breakout (17-Nov-2009)

Generic Policy Control for Local Breakout

Idea: Thomas Theimer, Joachim Charzinski

This report is related to packet switched transport of traffic in cellular networks such as GSM (GPRS,

EDGE), 3G (UMTS, HSxPA) and LTE (acronyms are listed at the end of this text). It is relevant both for

residential access points (femto base stations, home (e)nodeBs) as well as for pico and macro base

stations (BTS, (e)nodeB) and controllers (RNC). Herein, a solution is offered to the problem of

offloading bulk traffic from the 3GPP radio access network and core networks of a mobile network

operator (MNO) by providing a flexible mechanism for selecting a suitable mobile packet gateway. It

can also be used to control whether and under which conditions data path optimizations such as

local Internet offload and local IP access are allowed for a specific context.

The term 'bulk' traffic is used in this report for any packet oriented traffic that does not bring value to

the operator with increasing volume, such as Internet access or peer-to-peer traffic within a flat rate

subscriber package. Driven by the deployment of HSDPA in 3G networks and by the competition with

fixed network operators (FNOs) and the flat rate data plans they offer, MNOs currently face the

problem of a drastic increase of bulk traffic in their networks, requiring them to continuously

upgrade the capacity of their networks, especially in the mobile backhaul, controller and core sites as

well as their core IP backbone networks. Network operators are currently asking for ways to offload

this bulk traffic to cheaper fixed network routes, and some of them will even accept solutions that

restrict customer mobility or other MNO specific functions if this allows for significant capacity

savings.

Figure 1 shows the basic architecture for Internet offload with different possible offload paths from

the mobile network of the operator via a fixed network to the Internet. Terminals (UE) 101 are

connected via a radio interface to a base station 102 (e.g. a nodeB, NB) which is in turn connected to

a radio network controller (RNC) 103 via a mobile backhaul 104. The mobile core network consists of

mobile packet gateways (GW) 105 and other elements (like SGSN/MME). The gateways allow

connection both to (non-bulk) operator services in the MNO service network 106 and to the Internet

120. At the same time there is an infrastructure of the fixed network operator (FNO) allowing

terminals 110 to connect e.g. (in the case of DSL - optical or cable access is similar) via a home router

and DSL modem 111, a DSLAM 112, some switches 113 to a BRAS 114 which performs the fixed

network IP edge functions. Via core network of the FNO with routers 115 and other equipment, the

connection to the Internet 120 is realized. Possible breakout points are e.g. to connect the nodeB

102 via line 131 to the...