An integrated approach for functional decomposition of future RAN

Software-defined radio access networks (SD-RAN), dense deployment of small cells with possible macro-overlay for users with high mobility, decoupled signaling and data transmissions, or beyond cellular green generation (BCG2) architecture for enhanced energy efficiency, etc. are some of the very active research themes and most promising technologies for future RAN architecture. In this chapter, we present the idea of an integrated deployment solution for energy efficient cellular networks combining the strengths of the above mentioned themes. While SD-RAN envisions a decoupled centralized control plane and data forwarding plane for flexible control, the BCG2 architecture calls for decoupling coverage from capacity and coverage is provided through always-on low-power signaling node for a larger geographical area; capacity is catered by various on-demand data nodes or small cells for maximum energy efficiency. We identify that a combined approach bringing in both decompositions together can, not only achieve greater benefits, but also facilitates the faster realization of both technologies. We propose the idea and design of a signaling controller which acts as a signaling node to provide always-on coverage, consuming low power, and at the same time also hosts the control plane functions for the SD-RAN through a general purpose processing platform. Phantom cell concept is also a similar idea where a normal macro cell provides interference control to densely deployed small cells, although, our preliminary results show that the proposed integrated architecture has much greater potential of energy savings in comparison to phantom cells as a signaling controller is supposed to consume minimal power in comparison with the normal macro cell BS.