Network Deployment for ATG Communications: A Cell-Free Approach Under the Hybrid Satellite-Terrestrial Network Architecture

Due to the increasing demand for Internet access on aircraft, air-to-ground (ATG) communications have recently received extensive attention. Determining the locations of ATG base stations (BSs) is an important guarantee for efficient ATG communications. To this end, we consider an aircraft-centric ATG network where the aircraft is served by its adjacent ATG BSs. For this scenario, we formulate an optimization problem to determine the best number and locations of ATG BSs, to maximize the average uplink channel capacity. The problem is shown to be discontinuous and nonconvex. To tackle this challenge, we first propose a stochastic subgradient-based method to determine the locations of ATG BSs, followed by an algorithm to further determine the minimum number of BSs that satisfies the communication requirements on the target routes. Due to the nonconvexity of the problem, the solution obtained by stochastic optimization is not unique. To address this issue, we further propose a clustering method to obtain a unique solution for practical implementation. Simulation results confirm the effectiveness of our proposed algorithm compared with existing ATG BS deployment methods.