The history of modern mobile telephony, which is about 30 years by now, has certainly been fascinating. The first analogue systems deployed in the early 1980s followed by GSM in the early 1990s provided users a basic voice service with mobility support. The addition of GPRS subsequently introduced support for packet-oriented mobile services. After about another 10 years or so, the third generation mobile system UMTS appeared with better capacity and higher throughput for packet services. For a long time, however, voice services dominated the operators' service offerings and the mobile network traffic. But just as the Internet changed the nature of fixed-access networks, it finally changed the usage of the mobile networks as well. In front of their computers at home, more and more users were realizing what a great source for information, entertainment, interactivity and productivity the Internet was. They also discovered new ways of communicating with others through, for example, chat. The wish, or in many cases probably the need, to bring the Internet along to wherever you happened to go, led to the mobile broadband revolution of recent years. In many markets, the best selling mobile device is no longer a phone but rather a mobile broadband modem for laptops and computers. This is a paradigm change that the whole mobile industry needs to understand and come to grips with.

For a mobile operator, the mobile broadband revolution with its rapidly increasing traffic volumes has resulted in a number of challenges. Our customers want ubiquitous network coverage, high bandwidths and reliable services for reasonable price, while investors and owners require constant efficiency improvements, reduced operational costs and higher profits. In order to cope with such diverse requirements, operators rely as always on the mobile communications industry to continuously improve already deployed networks but also, when the evolutionary tracks finally come to an end, to define new network solutions.

Currently we clearly see that if we rely on only enhancements to the GSM/GPRS/UMTS core and access networks, it will be impossible to cope with the foreseen future demands. In fact, they might not be enough even in the near-time. Therefore the SAE/LTE network developed by 3GPP is extremely important, not only for an operator like TeliaSonera, but also for the whole mobile industry. It is what we shall deploy and live with for a number of years in the new mobile broadband-dominated market place.

As the SAE/LTE network is important for the mobile industry, it will be absolutely necessary for everybody working in the area, or aiming to work in the area, to have a solid understanding of what the new network is capable of and what possibilities it provides. There is no doubt that this book, which appears just when the mobile industry starts its transition away from legacy GSM/GPRS and UMTS networks into the future, will become the reference work on SAE/LTE. There are no better-qualified persons than the authors of this book to provide both communication professionals and an interested general public with insights into the inner workings of SAE/LTE. Not only are they associated with one of the largest mobile network equipment vendors in the world, they have all actively contributed to and, in some cases, been the driving forces behind the development of SAE/LTE within 3GPP.