Dear Colleagues,

NGN (next generation network) is being so commonly and enthusiastically used, both by the scientific and industry communities, that it is becoming a kind of buzzword covering a myriad of research topics and industrial trends. Under this vast and heterogeneous field, some common directions can be distinguished, among others, IP and the Internet as universal public communication network, mobility and ubiquity, openness to applications, devices and access technologies, and the growing role of machine to machine communication. A lot of new services are being explored but research also focuses on adapting and integrating traditional features to these new networks.

Solutions for NGN are designed at different layers, sometimes cooperating but also competing between them. For instance, mobility can be tackled at the network layer using Mobile IP while SIP (Session Initiation Protocol) offers its approach at the application layer. The choice of the layer where to develop the solutions is a major issue and has impact in aspects like performance or ease of deployment in legacy infrastructures. It may also challenge the Internet paradigm of network neutrality by relocating the “intelligence” from the applications at the edges to the network core.

We thus believe that a careful election of the layer(s) is a fundamental issue in the NGN research and deserves the interest of this special issue. We welcome papers giving answers in this direction. Comparisons of solutions developed at different layers, performance evaluation (including simulation techniques), cross-layer architectures, discussions on the implication for the network control, are some of the topics to be considered. We are confident that this special issue will be of great interest to the research community.

Dr. Antonio Cuevas Casado
Guest Editor