Ultra-Dense Heterogeneous Networks

Driven  by the ever-increasing amount of mobile data, cellular networks evolve  from small cell network to ultra-dense heterogeneous networks, to  provide high system capacity and spectrum efficiency. By bringing base  stations (BSs) to the approximate spatial scale and number magnitude,  ultra-dense heterogeneous networks would definitely bring unprecedented  paradigm changes to the network design. Firstly, along with  densification of small cells, inter-cell interference becomes severe and  may deteriorate performance of mobile users. Assigning network  resources including bandwidth and time slots, while avoiding  interference, desires serious consideration. Secondly, the coverage area  of BSs becomes small and irregular, resulting in much frequent and  complicated handovers when mobile users move around. How to ensure  continuous communication and implement effective mobility management,  and inter-cell resource allocation and cooperation, remains a  challenging issue. Thirdly, such dynamic change in spatial dimension  enables us to re-investigate available and ongoing communications and  networking techniques, such as massive MIMO, CoMP, millimeter waves  (mmWaves), carrier aggregation, full duplex radio, and D2D  communications.

To address the aforementioned  challenging research issues, this book will investigate the service and  QoE provisioning in ultra-dense heterogeneous networks. In particular,  firstly we introduce ultra-dense heterogeneous networks by careful  definition regarding spatial deployment, generic characteristics, and  requirements of ultra-dense heterogeneous networks in order to ensure  QoE of mobile users. Secondly, we depict the resource management among  small cells in close proximity, mobility management for mobile users  (address the super-frequent handovers), and interference management  (dealing with the interference due to frequency-reuse in the vicinity).  Thirdly, we study the enabling factors, and the integration of  ultra-dense heterogeneous networks with enabling technologies, such as  massive-MIMO, cloud-RAN, mmWaves, D2D, IoT. Finally, we conclude the  book and indicate future directions and challenges.