Shabnam Sultana

Voice and Emergency Services

This chapter provides an in-depth view of voice services in EPS, including a description of emergency and priority services. In addition, it covers VoLTE, SRVCC and CSFB.

Subscriber Data Management

This chapter provides an in-depth view of subscriber data management functionality in EPS, including a description of the EPS entities handling subscriber data.

Voice Services in EPS

This chapter provides a description of the voice services that are provided over an EPC network, aiming to bring the whole EPS and its concepts together, analysing it from several different potential evolution paths and describes voice services delivered using IMS technology, Single-radio voice call continuity (SRVCC), Circuit-Switched fallback (CSFB) and IMS Emergency Calls and Priority Services.

Data Services in EPS

This chapter provides a description of the data services that will be used on an EPC network, aiming to bring the whole EPS and its concepts together, analysing it from several different potential evolution paths for the services, including messaging and machine-type applications.

Offload Functions and Simultaneous Multi-Access

This chapter provides a description of offload functions defined for EPS, including functions to offload the core network as well as functions to offload the 3GPP radio access.

Services in EPS

While GSM was revolutionizing communications and taking mobile telephony to the masses, the World Wide Web was having a similar effect on the Internet. The tremendous popularity of the Internet and its value to end-users in providing relevant applications and information is driving a demand for mobile Internet. The functionality of the Evolved Packet Core (EPC) enables the mobile network operator to offer a new set of services to the users through its flat architecture and enables products and network deployments to be built for bandwidth-intensive services from the very start. In addition, EPC provides a number of features to the operator in order to support provisioning, monitoring, control and charging of these services. EPC is designed for IP services; this means that, in theory, almost any application relying on IP communication can utilize the IP access service offered by EPC. IP networks higher layer functionality is implemented in client and server applications residing on a terminal and a network server respectively. The role of the radio network and packet core network is to provide IP communication between the two end-points, the two IP hosts.

EPS Network Entities and Interfaces

This chapter illustrates the different network entities, interfaces, protocols and procedures used in Evolved Packet System (EPS). EPS is an “all IP” system where all protocols are transported over IP networks. A network entity in EPS is what sometimes called a “logical entity.” This means that in the 3GPP standard it is a logically separate entity with a well-defined functionality. There are also well-defined interfaces between different network entities. This does not, however, imply that actual physical “boxes” implemented by vendors and deployed in real networks have to correspond one-to-one with the network entities in the standard. Vendors may implement a network entity as a standalone product, or may choose to combine different network entities in the same product. It can for example be beneficial to combine a Serving GW and a PDN GW in the same node in order to reduce the number of physical in order to nodes that the user plane has to traverse in nonroaming cases.

Mobile broadband and the core network evolution

The necessity for a global standard is driven by many factors, but there are two main points. First, the creation of a standard is important for interoperability in a truly global, multivendor operating environment. Operators wish to ensure that they are able to purchase network equipment from several vendors, ensuring competition. For this to be possible nodes from different vendors must inter-work with one another; this is achieved by specifying a set of “interface descriptions,” through which the different nodes on a network are able to communicate with one another. A global standard therefore ensures that an operator can select whichever network equipment vendor they like and that end-users are able to select whichever handset that they like; a handset from vendor A is able to connect to a base station from vendor B and vice versa. Secondly, the creation of a global standard is about reducing fragmentation in the market for all the actors involved in delivering network services to end-users; operators, chip manufacturers, equipment vendors, etc. A global standard ensures that there will be a certain market for the products that, for example, an equipment vendor develops. The larger the volume of production for a product, the greater the volume there is to spread the cost of production across the end-users that will use the products. Essentially, with increased volumes a vendor should be able to produce each node at a cheaper per unit cost. Vendors can then achieve profitability at lower price levels, which ultimately leads to a more cost-effective solution for both operators and end-users.

Session management and mobility

The most fundamental task of the Evolved Packet Core (EPC) is to provide IP connectivity to the terminal for both data and voice services. This is maybe an even more significant task than in GSM/WCDMA systems where the circuit-switched domain is also available. With EPS, only the IP-based packet-switched domain is available. The IP connectivity will have certain properties and characteristics depending on the scenario and the type of services that the user wants to access. First, the IP connectivity will be provided towards a certain IP network. This would in many cases be the Internet but it could also be a specific IP network where the telecom operator provides certain services. The IP connectivity would be provided using one or both of the available IP versions that is IPv4 and/or IPv6. Additionally, the IP connectivity should fulfill certain Quality of Service (QoS) requirements depending on the service being accessed. The connection may need to provide a certain guaranteed bit rate or allow a prioritized treatment over other connections.

Conclusions and Looking Ahead

The System Architecture Evolution (SAE) work and the development of the Evolved Packet Core (EPC) specifications are the major achievements carried out by 3GPP and its partners, involving the global mobile industry community. This is due to the fact that the SAE work has been targeting a significantly broader scope than previous 3GPP releases, extending the functionality of the 3GPP packet core architecture to also encompass interworking with access technologies standardized outside of 3GPP, as well as provide an evolved packet-only core for the next generation of mobile broadband access technology-LTE. This in turn created significant excitement and interest from a vast number of contributing companies, ranging from mobile telecom operators to telecom equipment and handset vendors as well as research institutions. Going forward from the EPC solution and specifications as of 3GPP Rel-8, there are obviously several areas that may be exploited and developed in the future. The authors of this book are convinced of the necessity that the decisions on the next steps to take should be based on strong commercial aspects, ensuring that the 3GPP focus remains on features and functions of interest to the global community of network operators, consumers and enterprise customers. With the specification work of EPC, 3GPP has provided an excellent platform for future core network evolution.