Enhancing LTE with Cloud-RAN and Load-Controlled Parasitic Antenna Arrays

Abstract

-Cloud radio access network (C-RAN) systems consisting of remote radio heads (RRHs) densely distributed in a coverage area and connected by optical fibers to a cloud infrastructure with large computational capabilities, have the potential to meet the ambitious objectives of next generation mobile networks. Actual implementations of C-RANs tackle fundamental technical and economic challenges. In this article, we present an end-to-end (E2E) solution for practically implementable C-RANs by providing innovative solutions to key issues such as the design of cost-effective hardware and powereffective signals for RRHs, efficient design and distribution of data and control traffic for coordinated communications and conception of a flexible and elastic architecture supporting 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 parasitic antenna array (LCPAA) where multiple antennas are fed by a single RF chain. Energy and spectral-efficient modulation as well as signaling schemes that are easy to implement are also provided. Additionally, the design presented for the fronthaul (FH) enables flexibility and elasticity in resource allocation to support BS virtualization. A layered-design of information control for the proposed E2E solution is presented.The feasibility and effectiveness of such LCPAA-enabled C-RAN system setup has been validated through an over-the-air (OTA) demonstration.

Hybrid Beamforming Optimization for UAV-Enabled mmWave Beamspace MIMO System

“…After the flight altitude h * is obtained, a 2D exhaustive search is used to achieve the optimal location planning x of UAV to the optimization problem (7).…”

“…To tackle this challenge, lots of studies have been developed in order to reduce the energy cost and the number of RF chains, such as load-controlled parasitic antenna arrays (LC-PAAs) [7], beam selection [8]- [11] and hybrid analog/digital precoding design [12]- [14]. The recent concept of "beamspace MIMO" has been exploited as a potential scheme to substantiality reduce the hardware cost of RF chains, where the discrete lens array (DLA) is considered for analog spatial beamforming [15].…”

Joint Altitude and Hybrid Beamspace Precoding Optimization for UAV-Enabled Multiuser mmWave MIMO System

“…To tackle this challenge, lots of studies have been developed to reduce the energy consumption and the number of RF chains, such as load-controlled parasitic antenna arrays (LC-PAAs) [12], [13], beam selection [14]- [17] and hybrid analog/digital precoding design [18]- [22]. The recent concept of "beamspace MIMO" has been exploited as a potential scheme to substantiality reduce the hardware cost of RF chains, where the discrete lens array (DLA) is considered for analog spatial beamforming [23], [24].…”