5G on the Horizon

Toward the fifth generation (5G) of wireless/mobile broadband, numerous devices and networks will be interconnected and traffic demand will constantly rise. Heterogeneity will also be a feature that is expected to characterize the emerging wireless world, as mixed usage of cells of diverse sizes and access points with different characteristics and technologies in an operating environment are necessary. Wireless networks pose specific requirements that need to be fulfilled. In this respect, approaches for introducing intelligence will be investigated by the research community. Intelligence shall provide energy- and cost-efficient solutions at which a certain application/service/quality provision is achieved. Particularly, the introduction of intelligence in heterogeneous network deployments and the cloud radio-access network (RAN) is investigated. Finally, elaboration on emerging enabling technologies for applying intelligence will focus on the recent concepts of software-defined networking (SDN) and network function virtualization (NFV). The wireless world is increasingly calling for the effective management of heterogeneous infrastructures to meet the future Internet (FI)requirements [1]-[4] in an energy-and cost-efficient manner. Wireless network operators are trying to satisfy the growing traffic demand [5] by deploying cells of various sizes (mostly small cells), instead of utilizing only typical macro-base stations (BSs). All these cells constitute the elements of heterogeneous infrastructures, which should be effectively managed by introducing intelligence. Accordingly, wireless communications have to properly address key challenges and requirements driven by multiple perspectives of society, environment, economy, users, and operators so as to successfully achieve the vision of an inclusive, cohesive, and sustainable society. The future networks should be capable of handling the complex context of operations characterized by a tenfold increase in traffic [6], various mobility levels, and interference. In addition, multiple requirements need to be met including quality of experience (QoE) satisfaction, energy-efficient operation (90% -improvement by 2020 [7]), resource efficiency, and cost efficiency. Taking into account a comprehensive approach with respect to the determination of requirements, complexity, and heterogeneity of the infrastructures, there is a holistic presentation of the key challenges stimulating next-generation wireless networks. To address the key challenges, there is a need for enhanced, next-generation mobile broadband through intelligence, so as to find the optimal system configuration that will maximize the benefits of the intelligence and proceed to successful