Configurable Virtual MIMO via UAV Swarm: Channel Modeling and Spatial Correlation Analysis

Air-to-ground wireless channel modeling for unmanned aerial vehicle (UAV) communications has been widely studied. However, channel modeling for UAV swarm-enabled cooperative communication still needs investigation, where the impact of UAV po-sitions on the spatial channel characteristics is of par-ticular importance. In this paper, we consider a UAV swarm-enabled virtual multiple input multiple output (MIMO) system, where multiple single-antenna UAVs cooperatively transmit to multiple ground users (GUs). We establish a common coordinate system, as well as a UAV swarm-oriented coordinate system, to de-scribe the relative positions of the GUs and the UAV elements, respectively. Based on the established co-ordinate systems, geometric ray superposition method is applied to describe the spatial channel matrix. The proposed modeling framework can be directly used to describe the line-of-sight and two-ray propagations, and can be extended for including more practical spa-tial features such as multipath scattering, inter-UAV blockage, and random UAV jittering, etc. Based on the proposed model, we further analyze the spatial corre-lation among the virtual MIMO links of GUs located at different positions. Via extensive simulations, we show that thanks to the flexible deployment of UAVs, the virtual MIMO array structure can be conveniently configured to get desired channel properties, such as the channel capacity, eigenvalue and condition number distribution, and spatial correlation distribution. This shows the possibility and importance of exploiting a new design dimension, i.e., the UAV swarm pattern, in such cooperative virtual MIMO systems.

Automated summary

This paper discusses the spatial channel modeling for UAV swarm-enabled cooperative communication systems, which can achieve desired channel characteristics through flexible deployment of UAVs, thus enabling cooperative channel communication. By establishing different coordinate systems and using geometric ray superposition method, the description and analysis of the spatial channel matrix can be realized.