Preface

In general, all-IP network architecture only provides "Best Effort" services for large volume of data flowing through the network. This massive amount of data and applications in different areas increasingly demand better treatment of the information. Many applications such as medicine, education, telecommunications, natural disasters, stock exchange markets or real-time services, require a superior treatment than the one offered by the "Best Effort" IP protocol.

The new requirements arising from this type of traffic and certain users' habits have produced the necessity of different levels of services and a more scalable architecture, with better support for mobility and increased data security. Large companies are increasing the use of data content, which requires greater bandwidth. Videoconferencing is a good example. There are also delay-sensitive applications like the stock exchange market.

The relentless use of mobile terminals and the growth of traffic over telecommunication networks, whether fixed or mobile, are a true global phenomenon in the field of telecommunications. The increasing use of mobile devices in recent years has been exponential. Nowadays, the number of mobile terminals exceeds that of personal computers. At the same time, we see that mobile networks are a good alternative to complement or replace existing gaps for Internet access in fixed networks, especially in developing countries.

The growth in the use of Telecommunications networks has come mainly with the third generation systems and voice traffic. With the current third generation and the arrival of the 4G, the number of mobile users in the world will exceed the number of landlines users. Audio and video streaming have had a significant increase, parallel to the requirements of bandwidth and quality of service demanded by those applications.

The increase in data traffic is due to the expansion of the Internet and all kinds of data and information on different types of networks. The success of IP-based applications such as web and broadband multimedia contents are a good example. These factors create new opportunities in the evolution of the Telecommunications Networks. Users demand communications services regardless whether the type of access is fixed or via radio, using mobile terminals. The services that users demand are not only traditional data, but interactive multimedia applications and voice (IMS). To do so, a certain quality of service (QoS) must be guaranteed.

The success of IP-based applications has produced a remarkable evolution of telecommunications into an all-IP network. In theory, the use of IP communications protocol facilitates the design of applications and services regardless the environment where they are used, either a wired or a wireless network. However, IP protocols were originally designed for fixed networks. Their behaviour and throughput are often affected when they are launched over wireless networks.

When it comes to quality of service in communications, IP-based networks alone do not provide adequate guarantees. Therefore, we need mechanisms to ensure the quality of service (QoS) required by applications. These mechanisms were designed for fixed networks and they operate regardless the conditions and status of the network. In wireless networks (Sensor, Manet, etc.), they must be related to the mobility protocols, since the points where a certain quality of service is provided may vary. The challenge is to maintain the requested QoS level while terminals move on and handovers occur.

The technology requires that the applications, algorithms, modelling and protocols that have worked successfully in fixed networks can be used with the same level of quality in mobile scenarios. The new-generation networks must support the IP protocol. This book covers topics key to the development of telecommunications networks researches that have been made by experts in different areas of telecommunications, such as 3G/4G, QoS, Sensor Networks, IMS, Routing, Algorithms and Modelling.

> **Professor Jesús Hamilton Ortiz**  University of Castilla La Mancha Spain

**Part 1** 

**New Generation Networks** 

**1. Introduction**

In recent years, wireless telecommunications systems have been prevalently motivated by the proliferation of a wide variety of wireless technologies, which use the air as a propagation medium. Additionally, users have been greatly attracted for wireless-based communications since they offer an improved user experience where information can be exchanged while changing the point of connection to the network. This increasing interest has led to the appearance of mobile devices such as smart phones, tablet PCs or netbooks which, equipped with multiple interfaces, allow *mobile users* to access network services and exchange information anywhere and at any time. To support this *always-connected* experience, communications networks are moving towards an *all-IP* scheme where an IP-based network core will act as connection point for a set of accessible networks based on different wireless technologies. This future scenario, referred to as the *Next Generation Networks* (NGNs), enables the convergence of different heterogeneous wireless access networks that combine all the

F. Pereniguez-Garcia, R. Marin-Lopez and A.F. Gomez-Skarmeta

**Access Control Solutions for** 

**Next Generation Networks** 

*Faculty of Computer Science, University of Murcia* 

**1**

*Spain* 

In a typical NGN scenario users are expected to be potentially mobile. Equipped with wireless-based multi-interface lightweight devices, users will go about their daily life (which implies to perform movements and changes of location) while demanding access to network services such as VoIP or video streaming. The concept of *mobility* demands session continuity when the user is moving across different networks. In other words, active communications need to be maintained without disruption (or limited breakdown) when the user changes its

This aspect is of vital importance in the context of NGNs to allow the user to roam seamlessly between different networks without experiencing temporal interruption or significant delays in active communications. Nevertheless, during the handoff, the connection to the network may for various reasons be interrupted, which causes a packet loss that finally impacts on the

Thus, to achieve mobility without interruptions and improve the quality of the service perceived by the user, it is crucial to reduce the time required to complete the handoff. The handoff process requires the execution of several tasks (N. Nasser et al. (2006)) that negatively affect the handoff latency. In particular, the authentication and key distribution processes have been proven to be one of the most critical components since they require considerable time (A. Dutta et al. (2008); Badra et al. (2007); C. Politis et al. (2004); Marin-Lopez et al. (2010); R. M. Lopez et al. (2007)). The implantation of these processes during the *network access control*

advantages offered by each wireless access technology per se.

connection point to the network during the so-called *handoff*.

on-going communications.
