Small Cell Networks - Theory, Deployment, and Management

"Any sufficiently advanced technology is indistinguishable from magic" - Arthur C. Clarke, Profiles of the Future. One of the most widely used devices that appears "magical" today is the Smartphone, which allows the user to speak instantaneously with people on the other side of the planet, can provide professional answers to any question, has access to a map of the entire world and can guide the user to any desired destination. However, the "magic" does not happen in the Smartphone but in the network, which enables its functionality, provides ultra-broadband wireless access and processes information to deliver voice and data services, invisible to the end-user. This capability has resulted in an remarkable growth of cellular network infrastructure and mobile devices. In 2014, the number of connected mobile devices for the first time exceeded the number of people on earth, increasing rapidly from zero to 7,6 billion connected devices and 3.7 billion unique subscribers in only 3 decades [GSMA, PopClock]. This has fundamentally transformed the way we communicate and access information. Today, we are on the brink of another significant change. While up to now the the network mainly served humans, in the future this capability will be increasingly be used by machines as well. This will not only lead to a continued growth in network capacity demand, but also to additional requirements in latency - which becomes the limiting factor for many applications. Currently, most of the data services reside in the Internet far away from the end-user, where the speed of light becomes the limiting factor for latency. To address this problem, processing will move closer to the user into a cloud computing infrastructure as part of the network. This allows reducing the latencies to support real-time applications such as augmented reality or efficient machine communication. With these changes, the future network is evolving to become our main interface with the virtual world, and increasingly also with the physical world, to simplify and automate much of life. This will allow us to effectively "create time" by improving the efficiency in everything we do [Weldon15]. Making this vision of the future network a reality will require both: - Ultra broadband wireless access, providing orders of magnitude improved performance, and - A flexible and programmable cloud computing infrastructure close to the edge of the wireless network. This book is focused on the first component, the wireless access network that connects the mobile devices, machines and objects to the processing cloud engine. The remainder of this introductory chapter outlines the industry challenge, argues that small cells are the answer, and provides a brief history of small cells. Finally, the rest of the book is introduced with an overview of the parts and chapters addressing the main challenges encountered when deploying and operating small cell networks.