Next Generation Networks (NGN)

The NGN concept is mainly used in two ways: 1) A broad concept encompassing the whole development of new network technologies, new access infrastructures and even new services, and 2) A focused concept of specific network architecture and related equipments, with one common IP core network deployed for the entire legacy, current and future access networks. The first definition is so broad that in a sense it covers the whole current chapter on technological trends. The second definition relates to the transition path towards a converged IP-based core and access network. In this report, the concept of NGN denotes the second definition. Here we distinguish between the Next Generation Core Network (NGCN) and Next Generation Access Network (NGAN). The NGCN is about the new switching, gateways and transmission equipments in the core network, enabling several access networks to use the same core network. The NGAN is about new access networks, like deployment of optical fibers, and the challenges derived from that.

ITU defines NGN as "a packet-based network able to provide telecommunication services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport related technologies. It enables unfettered access for users to networks and to competing service providers and/or services of their choice. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users".* ITU-T Recommendation Y.2001 In this definition there is a major emphasis on one of the main characteristics of IP platforms namely the separation of network and service layers.

NGN is about the transition from current dedicated voice (and radio/TV) networks to the IP-based networks. From a technology efficiency point of view this is a natural development of all network technologies. However, there are a number of problems connected to the overall organization of the NGN platforms, which are subject for discussions amongst regulators today. One of the main issues is the interconnection model which will be used in the NGN. Will this, for example, be dominated by the IP interconnection models like peering and transit, or will the PSTN interconnection and tariff regime be modified and used in the future NGN platforms?

In this section first the NGCN and then the most important NGANs are described and organised in two major categories, Fixed and Wireless:



Reference Documents Next Generation Core Networks (NGCN)

Figure 1 illustrates the difference between today’s telecom networks and tomorrow’s NGN platforms. Today, the PSTN, mobile networks, Cable TV networks and Wireless networks use several dedicated metro and core networks.

Figure 1: Today's Networks and Next Generation Networks

Source: Ofcom

Next Generation Core Networks (NGCN)

In the NGN platform all of these different access technologies share the same IP core network. The main arguments for transition to the NGN architecture are:

  • It is not efficient to maintain several core networks for different access networks. Substantial cost savings can be achieved due to the economy of scope inherent in a single converged network. BT predicts*  a reduction of costs by £1 billion per annum by 2008/2009 as a consequence of migrating to NGN.
    • According to BT, NGN enables improved time to market for new services and improves customer experience.
    • NGN enables the continued offering of services in the legacy access networks. For example, the analogue PSTN access line/service does not need to be changed in transition to NGN. The main changes here are the efficiencies gained in the core network, especially when one operator owns and operates several parallel core networks. The latter is the case for a majority of incumbent operators. So the operator on the one hand utilizes the backbone efficiency gains and on the other hand continues to make profit from the investments in the access networks.
    • NGN enables the provision of value added innovative services using the possibility that one core network is connected to and manages different access networks. For example, a SMS can be sent to a mobile subscriber to inform the users if there are problems with the operation of DSL.

These arguments show that the implementation of NGN is a radical change in the network architecture of incumbent telecom operators. This raises the question of the role of regulation in this process: Should the regulators get involved in the practical implementation of the NGN? The answer to this question is no, as it contradicts the new regulatory doctrine of telecom development, where the decision of technological changes is taken on the market and by the market players/industry. However, the regulator must make this clear in setting the constraints within which the industry should design their networks.

The role of regulation regarding NGN is on the one hand to make sure that effective competition can take place in the NGN era, and on the other hand to make sure that the consumers and the level of services they receive are not affected in a negative way in this transition.

Reference Documents Next Generation Access Networks (NGAN)

Due to the wide spread of the installed base of the PSTN physical infrastructure, PSTN has been the basis for fast and efficient development and penetration of the Internet. In the pre broadband phase this was implemented by modulation of data signal in the same frequency spectrum as regular voice in the copper access lines. The data capacity in this frequency bandwidth is small and it can reach the maximum of 56 kbps. The next phase was introduction of ISDN, which improved the capacity and could offer 128 Kbps to residential households. While dial up PSTN modems and ISDN have had enormous impacts on the development of Internet access, today the Internet connectivity is mainly influenced by different broadband technologies. The new IP broadband infrastructures are in the literature denoted as the New/Next Generation Access technologies (NGAN). NGAN covers both the fixed (wired), wireless and mobile infrastructures, which enable IP connectivity to the households and companies. The terms NGAN and broadband can be used interchangeably, however the important thing is that NGAN is not only characterised by higher capacity networks but also by the two other main characteristics, namely: 1)'always on' provision model, and 2)the flat rate business model. With regards to the fixed networks the NGAN is mainly dominated by xDSL and cable modems. The advantages of the xDSL and cable modems are the availability of the physical infrastructure and by that the low deployment cost. Other fixed technologies like PLC have been on the market for some time, however it is difficult to see how this technology can compete on the NGAN market other than when it comes to home networking, which is at best peripheral to NGAN. Another fixed network with huge potentials is the fibre access networks. NGAN is also affected by the development of wireless and mobile technologies. Wi-Fi and WiMAX and their combination seems to have huge potentials. Also satellite, broadcast and new mobile infrastructures are important in development of NGAN. In this section the most important NGAN are described and organised in two major categories, Fixed and Wireless:



Practice Notes

Reference Documents

Next: 7.1.5 Convergence