Robust Power Control for Spectrum Sharing Vehicular Communications Using OTFS Modulation

Orthogonal time frequency space (OTFS) is a promising two-dimensional modulation technique to provide better communication performance than orthogonal frequency division multiplexing in high mobility scenarios. Since the channel parameters in such scenarios vary fast, they are hard to be acquired timely and accurately. In this correspondence, we focus on spectrum sharing vehicular communication networks that use OTFS modulation to mitigate the Doppler effect with imperfect channel state information (CSI). We aim to optimize the transmit powers to maximize the average achievable rate of the vehicle-to-infrastructure (V2I) link, while meeting the reliability requirement of the vehicle-to-vehicle (V2V) link. To tackle this non-convex optimization problem, we propose an efficient algorithm named constrained stochastic successive convex approximation (CSSCA)-based power control algorithm by constructing convex surrogate functions of both the objective and constraint functions. Simulation results validate the convergence and the robustness of the proposed algorithm as compared to the benchmark schemes.