3D Placement of Drone-Mounted Remote Radio Head for Minimum Transmission Power Under Connectivity Constraints

Dense small cell deployment in a cloud radio access network (C-RAN) is an effective approach to satisfy the increasing requirements of the emerging fifth generation (5G) mobile networks. Nevertheless, the optimal deployment of small cells is not always possible due to certain limitations, such as the existence of backbone infrastructure and appropriate power supply. In addition, the increased throughput requirements in a certain area may be temporal, such as in the case of an event such as a sports match or a concert. To this end, the leverage of multiple drone-mounted remote radio heads (D-RRHs), coupled with advanced user scheduling and multiplexing schemes, can be a promising asset in provisioning an on-demand and dynamic C-RAN. Nevertheless, finding the optimal placement of the D-RRHs, under certain quality of service (QoS) constraints can be challenging. In this work, we propose a D-RRH placement approach that minimizes the transmission power by optimally placing the D-RRH. We formulate the placement optimization problem and decouple it into two separate sub-problems, namely the horizontal placement and the vertical placement problems. An implementation of the Weiszfeld algorithm is utilized in order to solve the horizontal placement problem by finding the point that minimizes the sum distances. The vertical placement problem is calculated as a function of the optimal elevation angle and the radius of the coverage area. In order to evaluate the performance of the proposed approach, we carried out extensive evaluations and compare our proposed approach against two similar approaches. The evaluation results show the feasibility of the proposed approach in minimizing the required transmission power and maintaining fairly good performance in terms of user connectivity.