It is clear that the SAE work and the development of the EPC specifications is a major achievement 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.

Inclusion of CDMA interworking capabilities in the 3GPP architecture is naturally a major breakthrough, paving the way for network deployments of LTE and EPC that can be shared across an even wider operator community, as well as closer cooperation between 3GPP and 3GPP2. Global uptake of a single common technology means large volumes of handsets and network equipment, a highly competitive market leading to focus on cost efficient solutions and lots of attention from service and application developers. A global technology also means excellent roaming possibilities in that users can access and utilize services in a large number of countries while using their own personal mobile device.

Before closing this book, let us spend a few moments looking into the near future, even though the deployment of LTE and EPC networks are still in its early phase. Work on EPC will continue with the next phase, and there are a number of areas which can be exploited in terms of adding new features to the architecture further.

In near term, 3GPP is addressing a number of areas and features for Rel-9. The focus of this work is on solutions and architecture for handling specific telephony requirements (such as support for emergency access over EPC) and for small base stations for deployment in offices or homes (the so-called femto base stations or Home NodeB/eNodeB’s). There are a number of other suggestions for enhancements and additions, including, for example, enhanced broadcasting over LTE and WCDMA (eMBMS) as well as more advanced mechanisms for supporting simultaneous connections over multiple radio access networks.

The impact from possible deployment of small base stations in the private homes of end-users is one focus area for the continued EPS evolution. These small base stations, referred to as femto or home base stations, would interconnect to the mobile network over fixed broadband connections that are assumed to be present in the homes of end-users. This solution could potentially offer operators cost efficient solutions for increasing network coverage and capacity while enabling new service offerings to the users.

Potential future deployments of telephony services based on IMS requires that a number of legal requirements are fulfilled, somewhat differing between countries and associated licence requirements for mobile network operators. These requirements include support for emergency calls, for example, over networks where the user in the emergency situation is not a subscriber. Emergency calls also often require that the geographical position of the user making the call is made available to the applicable authorities with sufficient accuracy. These requirements will also impact the evolution of EPC.

Broadcasting would allow for a more efficient resource usage in the case that many receivers shall receive the same content. This can be solved through transmitting the contents only once, and not once per user. This is already supported as part of the WCDMA/HSPA MBMS specifications, where MBMS is short for Multimedia Broadcast/Multicast Service. The corresponding feature in Rel-9 for LTE and WCDMA is called evolved MBMS (eMBMS).

One additional important activity that will influence EPC in the future is the work on evolving the LTE access towards capabilities matching the ITU definitions of ‘IMT-advanced’. This work was started in 3GPP in 2008, and although the basic assumption is that the core network architecture and procedures shall remain as defined in Rel-9, the possibility that the core network will in fact be impacted cannot be ruled out at this early stages of development phase. The evolution of LTE can be assumed to be included earliest in 3GPP Rel-10 specifications.

Target requirements on LTE meeting IMT-advanced criteria can be found in 3GPP TR 36.913, [36.913] and include:

• Building on and evolving Rel-8 LTE including maintaining support for all relevant LTE requirements.

• Meeting or exceeding the ITU-R IMT-advanced requirements.

• A downlink peak data rate of 1 Gbit/s and an uplink peak data rate of 500 Mbit/s.

• Transition time from idle to connected mode less than 50 ms.

• Transition from dormant to active state in connected mode less than 10 ms.

• Reduced user plane latency compared to Rel-8 LTE.

• Downlink peak spectrum efficiency of 30 bps/Hz and uplink peak spectrum efficiency of 15 bps/Hz, assuming antenna configurations of 8 × 8 or less for DL and 4 × 4 or less for UL.

• Improved VoIP capacity compared to Rel-8 LTE.

• Support mobility for speeds up to 350 km/h or 500 km/h depending on the frequency band.

• Coverage requirements as for LTE Rel-8.

• Backwards compatibility in that Rel-8 LTE terminals can be supported and that new terminals supporting evolved LTE can work in a Rel-8 LTE network.

• Support for additional frequency bands and wider bandwidths (up to 100 MHz) compared to Rel-8 LTE.

• Support for handover to legacy mobile networks with capabilities and performance the same or better than for LTE Rel-8.

• Support for network sharing.

• Cost efficient solutions in general, addressing, for example, power consumption, backhaul costs, operation and maintenance, etc.

It remains to be seen to what extent these LTE requirements will also impact EPC. It should be noted that actual network deployments including Rel-10 based evolved LTE capabilities are several years away.

In addition to the features discussed above, there are also some smaller improvements being studied currently, focusing on more alignment of non-3GPP accesses with the 3GPP services.

Looking beyond pure mobile networks, the area of common solutions for fixed and mobile access has seen a lot of attention from large operators with both mobile and fixed business interests. While 3GPP Rel-8 specifies generic mechanisms for interconnection between EPC and just about any other network based on Mobile IP/Proxy Mobile IP mechanisms, there is a potential of further harmonization of, for instance, subscriber management and policy control across fixed and mobile access technologies. One common way of controlling subscriber credentials, access rights and service usage should prove valuable to operators wanting to provide a generic service offering over both fixed and mobile accesses. Such a harmonization would most likely require a close cooperation between 3GPP and the Broadband Forum (BBF) to arrive at common solutions.