In recent years, the use of UAVs (Unmanned Aerial Vehicles) to boost mobile networking technology performance is rising interest in the scientific community. UAVs can be used as aerial relays to be deployed in 4G/LTE networks and small scale UAVs, such as quadrotors or small fixed wing drones, are able to carry a wide variety of sensors, actuators and communication equipments. Due to the increasing interest in this field, UAVs are becoming more and more affordable and even off-the-shelf quadrotor UAVs can carry payloads of few kilograms. In parallel, the miniaturization of commercial femto cells results in the development of very lightweight network equipment. The combination of UAVs and cellular network equipment provides an interesting approach towards the enhancement of performance of a network. Most of the applications of UAVs are thought as relay deployment in order to compensate for temporary cell overload or cell outage in cellular networks. In this project, by merging the multidisciplinary knowledge of participants, we will study and propose approaches for boosting cellular network performance through the use of UAVs as Drone-Base Stations (Drone-BS). We will look both at an optimization of the Drone-BS deployment for an optimal coverage given their communication capabilities as well as their optimal mission planning having as constraints the UAV characteristics (e.g. battery lifetime, maximum achievable speed, coverage etc) and environmental conditions.
As previously indicated, the use of UAV-aided wireless communication offers one promising solution to provide wireless connectivity for devices without infrastructure coverage due to, say, severe shadowing by urban or mountainous terrain, or damage to the communication infrastructure caused by natural disasters.
Novelties of this proposal will be:
1) Detailed analysis of drone characteristics and cellular technologies to provide the aforementioned "connectivity from the sky".
2) Optimization mechanisms for Drone-BSs deployed to assist the existing communication infrastructure in providing seamless wireless coverage within the serving area,
3) Analysis and proposal of suitable beamforming methodologies for a secure and efficient use of UAV as relay and Drone-BS
4) Combining robust navigation and flight formation decentralized control strategies with energy efficiency.
5) An integrated simulation framework abstracting the models and results of WP 2 and 3.
As for innovation 1, the comprehensive modeling of a 5G heterogeneous network (drone and macro BS based) will be provided, over a partially destructed/offloaded cellular network. The impact of various parameters such as pathloss, number of Drone-BS, density of base stations, and the altitude of the Drone-BS will be investigated.
As for innovation 2, we will contribute to analyse the optimal Drone-BS altitude which leads to a maximum ground coverage and minimum required transmit power for a single Drone-BS. Furthermore, the problem of providing a maximum coverage for a certain geographical area using multiple drones will be investigated. The impact of the distance between Drone-BS on the coverage area will be studied and the optimal distance between drones resulting in maximum coverage is derived. Numerical analysis will be used to verify the existence of optimal Drone-BS altitude/separation distance and provide insights on the optimal deployment of Drone-BS to supplement wireless network coverage.
As for innovations 3 and 4, since secure and energy efficient communications protocols are key parameters to guarantee success in UAVs operations we will look at both aspects. As for security, malicious attackers could not only exploit UAVs sensitive information, but also jeopardize the safety of the mission surrounding environment.
While omnidirectional transmissions broadcast signal energy everywhere allowing any user in range to overhear the transmission, adaptive beamforming ensure spatial multiplexing capabilities and therefore, a higher level of security.
MIMO beamforming in this project will then allow to enhance communication throughput while combating jamming and drone hacking.
Connectivity and beamforming are maintained through formation control. This project is aimed at combining control algorithms providing robust navigation and decentralized flight formation with energy requirements.
Finally, innovation 5 is in the integration of the solutions derived in the two main project WPs (2 and 3). In this framework a comprehensive simulation tool abstracting the main models and results of the WP2 and WP3 will be designed and used to evaluate the overall behavior of the proposed approach in significant case studies. The software tool will potentially be used in the scientific community as a global simulator integrating control and communication models in the framework of the Drone Cellular Networks.
As far as we know, no tools like this are currently available for a comprehensive performance evaluation.