1.1 Book Content and Organization

Even though the scope of the book is to give a unitary view of telecommunications under a technical point of view, it is simply impossible to include in a single book all the various elements that combined form the telecommunication network. Thus, some choices have to be made.

The first clear choice is to exclude all forms of free space communication and related networking techniques. Radio bridges are no longer used as transmission trunks in the network, but only for particular situations, generally in the access area. Almost all the wireless segment of the network is constituted by the cellular infrastructure that is a relevant part of the access network.

Even if a strong push by the market exists toward a services and techniques convergence of wireless and wired access networks, the cellular network has up to now evolved with its own standards and specific equipment.

Even radio technology used in cellular equipment is not utilized in other telecommunication equipment, having, on the contrary, common elements with other applications of the radio technology like radars, free space communications between moving platforms (like airplanes or ships), and similar systems.

Therefore, in Chapter 2, wireless access is considered only to look at wireless services. Readers interested in the wireless technology are encouraged to access the rich technical bibliography.

Also, software technology is considered only marginally in this book, even if its evolution is instrumental in the present transformation of telecommunication engineering.

This will result evident from the great attention devoted to the network control procedures, whose evolution would be impossible without modern software development techniques.

Considering the different areas in which the wireline telecommunication network is divided, the greater attention is reserved to the so-called core network: that part of the network covering geographical areas that are extended over a continent or a big country. Here optical transmission systems convey thousands of Gbit/s over distances of thousands of kilometers, and IP routers of the capacity of several Tbit/s carry out the basic operations of the Internet. Service sources, like video on demand, IP TV servers, soft switches for the IP phone, and so on, are generally located in the core network nodes.

The core network is divided into several subareas, different for capacity, extension and role: backbone, metro core, and regional. The characteristics of these different subnetworks are analyzed in detail.

The end user has the possibility to access the resources of the core network through the access network. Architectures and technologies of the access network, which are key for the carriers’ success, are also analyzed, focusing particularly on the evolution from the copper-based access to the fiber-based access.

In any case, the analysis has been presented keeping engineering practice in mind, even when complex concepts of modern physics or of control structures have been considered.

Instead of general and abstract results, the book tries, through a great number of examples, to evidence the practical elements of the design of key communication equipment.

Some of these examples are synthetic exercises of design that are conceived to put the reader in front of a realistic coexistence of all the elements in a single equipment, instead of insisting on the separate analysis of different design points.

In every case, for simple components and for the more complex equipment, realistic values of the system parameters have been reported by collecting information from the products available on the market. In this way, the reader is provided with an extended database of what present-day technology can do, which is necessary to understand, at first glance, if a set of requirements is within the reach of the technology.

In this context, Chapter 2 is devoted to an analysis of the recent history and of the present status of the telecommunication market, so as to be able to derive requirements for the network evolution from market trends.

Chapter 3 gives a general overview of the current networking techniques, while Chapters 4 through 7 review the core network in detail from the technology, network element, and architecture points of view.

Not only are consolidated techniques illustrated, but the main evolution directions are also considered. In any case, a large volume of numerical examples gives solid structure to the different subjects.

While in the first seven chapters we have mainly considered engineering techniques, we enter the research labs in Chapters 8 through 10 to present the latest techniques in the telecommunication field that will shape the long-term network evolution.

The book concludes with a chapter on access optical technology.

1.2 Using This Book

Requisites for a full exploitation of this book’s potential are the technical culture typical of an engineer (not necessarily one working in the field) or of an advanced PhD student in engineering or physics as well as a very basic knowledge of telecommunication services.

Following are examples of potential users of this book:

The industry manager, who can have a clear and complete idea of the helping him to consider correctly also key elements that are at the edge of his or her core area of competence. Due to its strong focus on interdependence, the book offers critical help in the decision process and could well become a working instrument for technical and marketing managers.

The designer, who can have a global idea of new technologies so as to channelize his or her work in the most suitable direction and to make design choices having a complete view of the possible alternatives.

The university professor, who can study the connection between market trends and technology evolution among the different technical areas (e.g., technology and network architecture) so as to transmit this to the students. Due to its structure, the book should be useful in carrying out research for an up-to-date university course in tune with the latest realistic trends. Finally, a university professor can also use this book to update himself or herself on aspects of telecommunications that fall within the core area of his or her competencies.

The senior student, who can use this book to decide where to direct his or her activity and to acquire an organized view of the wider telecommunication environment.

Finally, a comment on the organization of the bibliography. We have chosen not to mention who has discovered a certain technique or which research group has first introduced a certain type of analysis. Frequently, the first work in which a concept appears is neither the most complete nor the most useful from a didactical point of view. We have decided to mention only those papers that have helped us in gaining more insight into a topic or in explaining it. Where possible, we have cited complete works, or even books if available.

Acknowledgments

This book would not have been possible without the continuous support and encouragement of my wife Flavia and of my three children Emanuele, Maria Grazia, and Gabriele.

I enjoyed the rare advantage of finding in my wife dedication, understanding, support, and technical help, and I took full advantage from them.

My friends and colleagues have provided a great number of suggestions and discussions that have been invaluable. Among them, I would like to thank, in particular, Stefano Santoni, Massimo Gentili, Marco Romagnoli, and Roberto Sabella for their help in reviewing a few key points of the book.

I would also like to remember Filippo Bentivoglio. At the very beginning of optical networking, Filippo and I worked together in the exciting mission of defining a complete new network layer. A few still valid concepts regarding optical protection (and a few schemes relating to that) derive from our common work.