Heterogeneous cloud radio access networks [Guest Editorial]

With the rapid development of mobile Internet and the Internet of Things, the demand for high-speed highquality data applications, such as wireless video streaming, mobile interactive gaming, social networking, and machine-to-machine communications, has been growing dramatically. To meet this rapidly growing demand, there is an urgent need for revolutionary approaches involving new wireless network architectures as well as advanced networking technologies. Heterogeneous networks (HetNets) have attracted significant interest from both academia and industry as a means to potentially improve spatial reuse and coverage, thus allowing cellular systems to achieve higher data rates, while retaining the seamless connectivity and mobility of cellular networks. However, considering the severe inter-tier interference and limited cooperative gains, new techniques for improving both the spectral efficiency and energy efficiency through suppressing inter-tier interference and enhancing cooperative processing capabilities are needed. On the other hand, cloud computing technologies have emerged as a promising solution for providing high energy efficiency together with flexibility through software defined virtualization of communication networks and protocols. Consequently, heterogeneous cloud radio access networks (H-CRANs) that combine HetNets with cloud computing have been recognized as a potential cost-effective solution for alleviating inter-tier interference and improving cooperative processing gains in HetNets.