Aerial-Ground Integrated Vehicular Networks: A UAV-Vehicle Collaboration Perspective

Unmanned aerial vehicle mounted base stations (UAV-BSs) are expected to become an integral component of future intelligent transportation systems, which can provide seamless coverage for vehicles on highways with poor cellular infrastructures. Motivated by the above, this paper proposes an aerial-ground integrated vehicular networking architecture, based on which a UAV-vehicle collaboration perspective is proposed. Specifically, an emerging vehicle-to-UAV (V2U) and vehicle-to-vehicle (V2V) collaboration framework is first presented to facilitate diverse vehicular applications. Next, we investigate the coverage radius maximization problem by optimizing the UAV-BS altitude. Meanwhile, by taking the channel state information (CSI) feedback delay into account, we formulate a V2U communication sum rate maximization problem by optimizing the power control and spectrum allocation, which is constrained by the capacity and reliability requirements. Then, we derive the closed-form expression of optimal UAV-BS altitude. Afterwards, we decouple the formulated sum rate maximization problem, and devise an efficient algorithm with polynomial complexity, where the optimal power control and spectrum sharing are solved. Finally, simulation results demonstrate that the maximum coverage radius and optimal UAV-BS altitude can be achieved by our proposed scheme in different urban environments. In addition, our designed scheme can effectively improve the V2U communication sum rate in comparison with the current works.

I. Introduction

As a prominent component of Internet of Things (IoT), vehicular networks gain a lot of attention from academic and industry [1]. Meanwhile, the automotive industry is witnessing a qualitative shift, with the wide application of wireless communication technologies [2]. Under this background, in order to implement intelligent transportation systems (ITS), future vehicular networks require the high-speed, low-latency, high-capacity, and ultra-reliable connectivity [3]. To achieve these goals, vehicle-to-everything (V2X) techniques can be viewed as promising communication approaches in 5G-and-beyond (B5G) era. By merging different types of communication approaches (e.g., vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V)), V2X techniques can ensure road safety, provide traffic management services, and support various entertainment services [4], [5], [6]. Specifically, V2I communications with high-capacity can satisfy the demand of entertainment-oriented applications, and V2V communications with high-reliability can ensure the safety-critical transmissions between vehicles [7].