In the mid of 2015, the first phase of 5^th Generation Public Private Partnership (5G PPP) projects kicked off, and the time until now has been hectic, but also very rewarding. During this period, 5G has moved from vision and concepts to technologies that are almost ready to be deployed, and we are glad and proud to have been part of this work.

This book is based on the outcome of 12 projects within the 5G PPP framework, as detailed in Section 1.2, and complemented by contributions from various additional 5G experts across the globe. We would like to thank all the contributors for the substantial effort and engagement invested into this book, despite the fact that the writing of the book collided with that of the final deliverables of most of the involved projects. In particular, we would like to express a big thank you to the main chapter editors for consolidating the often diverse viewpoints and terminologies used by different projects or entities into a coherent story. Knowing that many contributors have also spent their free time to finalize the book, and given that the work behind the development of new technologies like 5G is typically as demanding and time‐consuming as it is rewarding and inspiring, we would also like to thank the families of the contributors for their continuous patience and support.

Naturally, we would like to thank the European Commission for funding the projects that have led to this book, and in particular Bernard Barani for his personal support of the book.

Beyond the researchers who have been directly involved in the projects, there are of course much more persons involved in our home organizations. We would hence like to thank all our colleagues in the mobile communications industry, research institutes and universities for inspiring discussions, the contribution of ideas, and the help on various tasks.

Dr. Bulakçı would also like to thank Wu Jianjun and Dr. Egon Schulz from Huawei for the support in preparation of this book.

Last but not least, we would like to thank Sandra Grayson, Louis Manoharan and Adalfin Jayasingh from Wiley for the pleasant collaboration and continuous support throughout the writing and production process of this book.