This book contains 12 chapters. The first chapter is dedicated to the road to 5G - its visions and challenges. The second chapter discusses the new 5G air interface: challenges for efficient multi-service coexistence for 5G below 6 GHz. The third chapter discusses the new quasi-deterministic approach to channel modeling in millimetre-wave bands. The fourth, fifth and sixth chapters represent, for large-scale antenna systems, the effects of densification and randomness of infrastructure deployment in cellular networks and wireless device-to-device (D2D) links for machine-to-machine (M2M) communication. The seventh chapter presents the caching in large wireless networks. The eighth, ninth and tenth chapters discuss the decoupled uplink and downlink access in heterogeneous networks, full duplexing and wireless network virtualization. The eleventhe chapter presents the licensed shared access (LSA) and three-tier spectrum-sharing models' regulation, business and technology perspectives, and the final chapter discusses wireless beyond 5G.