Having already entered the initial phase of the 5th generation networks (5G) era, the network ecosystems have already begun comprising a plethora of coexisting 3GPP and non-3GGP Radio Access Technologies (RATs). Deployment scenarios envision a multi-layer use of macro, micro and femto-cells, where multimode end devices, supporting different applications, are served by heterogeneous access technologies. At the same time, this heterogeneous environment results in an abstract pool of resources, moving away from the traditional cell concept and exposing the network administrator with the collective resources in time, frequency, and space. An imperative need is thus created, to obtain an overview of the network and radio conditions in order to respond in an optimal way. The concepts of Software Defined Networking (SDN) and Software Defined Radio (SDR), when applied in a coordinated and sophisticated manner, may prove of utmost importance towards addressing the aforementioned challenges. The concept of network slicing -that enables the creation of several virtual networks with diverse characteristics, on top of common infrastructure- further reinforces the flexibility and dynamicity of the network. To this end, we present and evaluate a Cross Layer Controller (CLC), which acts on top of well-established SDN and SDR technologies, and monitors in real-time the conditions in the radio environment, as well as the transport network traffic, in a unified way; based on this dynamic input, CLC enforces sophisticated, end-to-end resource allocation policies and pairing mechanisms between network slices from different network segments, highlighting thus, the feature of cross layer resource management and dynamic adaptation. The experimentation results demonstrate the considerable gains acquired from the proposed solution.
