Enabled by the emergence of high-speed Internet access in last mile communications, P2P systems have witnessed significant growth in the recent years, mainly due to their intrinsic characteristic of being independent of the underlying network and the different services that operators offer in various subscription models. The advent of the Next Generation Networks (NGN) technology is expected to further strengthen the growth of P2P services as it will allow their deployment in any network and with any terminal type. In this chapter, the author first gives an overview of the NGN technology, and then presents its first real implementation called the IP Multimedia Sub-system (IMS), with a discussion of the issues on integrating and interworking P2P applications in converged communications networks.
TopIntroduction
Achieving seamless interworking between fixed and mobile networks is one of the main goals of contemporary networks technologies. The main driver for achieving this goal is the requirement for establishing IP communications convergence over heterogeneous networks, where networks of different protocols and physical communication technologies could come together under a common communications framework in order to offer service uniformity and seamless continuity through the establishment of common user management procedures (e.g. authentication, mobility management, etc.).
To enable the roll out of integrated fixed-mobile network services on the market, several standardization bodies and industrial forums have been involved in definition of architectures that function as overlay communication frameworks for current technology networks. In this process, the ITU (International Telecommunications Union) paved the way with definition of Next Generation Networks (NGN) technology, in which it recommends a number of generic mechanisms for the following:
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Packet-based communications between different access technology networks
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The integration of signalling and data management procedures of different network technologies within the Internet Protocol (IP)
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Common services deployment in mobile, wireless and fixed networks
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Quality of Service (QoS) implementation in mixed communication scenarios over heterogeneous networks
Following ITU recommendations, two standardization organizations of the telecommunication industry: 3GPP (3G UMTS Partnership Project) and ETSI (European Telecommunications Standardization Institute) went further to define the first real implementation of NGN network, the IP Multimedia Sub-system (IMS).
The IMS is independent of the underlying protocols of the data plane (as long as they are implemented over IP) and handles only the signalling and traffic management operations using the Session Initiation Protocol (SIP; Rosenberg 2002) as a unification mechanism for all user procedures.
This chapter aims to explain how integration and interworking of fixed and mobile networks is achieved in the context of IMS technology. The description commences with the definitions for network convergence and main principles, which is then followed by an explanation of the IMS components and procedures, and finally a discussion of the issues concerning the binding of P2P services with NGN networks.
TopBackground: Towards Achieving Fixed And Mobile Networks Interoperability
Achieving interoperability between different technology networks has been a major goal of the telecommunications industry in order to achieve services uniformity and homogeneous user management mechanisms. The advent of IP and the widespread adoption of Internet communications have unveiled the potential of huge revenues out of the use of user-driven applications. The first effort for introducing IP communications in the context of subscriber networks has been made with the definition of NGN by ITU and latter with the definition of IMS by 3GPP and ETSI.
Today, IMS networks have been deployed experimentally by operators and research groups, with the objective of assessing the quality of high bandwidth communication services, such as multimedia streaming, IPTV and distributed P2P applications.
Although a high-level comparison of NGNs with P2P communication architectures reveals that the two systems are antagonistic, i.e. NGNs being centralized network architectures and P2P being highly distributed software entities that function autonomously, the two systems may in reality function complementarily, e.g. NGNs can provide a service environment that ensures portability of P2P applications in all-IP networks (Chen et al., 2006). On the other hand, by providing the network infrastructure with many degrees of freedom, P2P applications are emerging as an easy way of implementing ‘pay-and-go’ applications, without having to invest in expensive centralised service execution environments (Yao & Chen, 2007). Following this observation, recent research efforts have recognised the potential of NGN for accommodating P2P applications, and have focused on solving a number of integration issues.