Enhancing LTE Technologies with Joint Cloud-RAN and Load-Controlled Antenna Arrays

Cloud-RAN systems consisting of remote radio heads (RRHs) densely and randomly distributed in a coverage area and connected by optical fibers to a cloud infrastructure with potentially unlimited computational capabilities have the potentials to meet the ambitious objectives of next generation mobile networks. Actual implementations of Cloud-RANs tackle fundamental technical and economic challenges. In this article we present an end-to-end global solution for practically implementable Cloud-RANs by providing innovative solutions to key issues such as the design of cost-effective hardware and power-effective signals for RRHs, efficient design and distribution of data and control traffic for coordinated communications, and conception of a flexible and elastic architecture supporting a dynamic allocation of both the densely distributed RRHs and the centralized processing resources in the cloud to create virtual base-stations (BSs). More specifically, we propose a novel antenna array architecture called load-controlled antenna array (LCAA) where multiple antennas are fed by a single RF chain. Energy and spectral-efficient modulation and signaling schemes easy to implement are also provided. The design presented for the mobile fronthaul (MFH) enables flexibility and elasticity in resource allocation to support BS virtualization. A layered-design of information control for the proposed end-to-end solution is presented. The feasibility and effectiveness of such LCAA- and MFH-enabled C-RAN system setup has been validated through an over-the-air (OTA) demonstration.