The
PS core network consists of two parts, the traditional General Packet Radio
Service (GPRS) core network and the new Evolved Packet System (EPS) core
network. The PS core network connects mobile
subscribers to Packet Data Networks (PDNs) such as the Internet, corporate
networks or operator services networks. a functional
overview of the PS core network.
Logical
entities and interfaces are shown in black and form a 2G/3G network, while the
blue boxes and lines in Figure show the LTE/EPC related parts.
The LTE/EPC network can be regarded as an extension and evolution of existing
2G/3G networks. From a node implementation perspective, there is no strict
border between the two networks. The corresponding logical entities of GPRS and
EPS networks can be deployed concurrently in Ericsson PS core nodes, such as
the SGSN-MME and EPG; these are marked in red. In addition, Ericsson GPRS nodes
can be upgraded with EPC functionality by software only.
Network
evolution is supported by the following Ericsson PS core products.
·
Serving GPRS Support Node - Mobility Management Entity (SGSN-MME)
- The SGSN-MME acts either as the SGSN for GPRS core network, or as the MME for
EPC network, or as a combination of both SGSN and MME.
·
Evolved Packet Gateway (EPG) - EPG allows simultaneous combination
of the Gateway GPRS Support Node (GGSN), Serving Gateway (SGW), and PDN Gateway
(PGW) functions on one physical node.
As part of
the evolution of EPC, the Policy and Charging Control (PCC) architecture, shown
in Figure 3, is mainly provided by the
Policy and Charging Rules Function (PCRF), the Policy and Charging Enforcement
Function (PCEF), the Application Function (AF) and the Online/Offline Charging
System (OCS and OFCS) entities. Ericsson Service-Aware Charging and Control
(SACC) solution provides complete and validated PCC functions based on the following
Ericsson PS core products:
·
Service Aware Policy Controller (SAPC) - SAPC implements the PCRF
function as described by the 3GPP PCC standards.
·
Service Aware Support Node (SASN) - SASN is a standalone PCEF
entity and can be deployed on the Gi/SGi interface between the EPG and Internet
Security and Gateway functions.
·
EPG - as a combined gateway platform for GGSN, SGW and PGW, the EPG
contains a PCEF function for PCC architecture. The service awareness function
in the SACC Solution is based on an advanced packet inspection available integrated
in EPG or standalone in SASN.