Spectrum Sharing Design for L-Band Aeronautical Communication and Navigation System

The study explores a novel framework for an integrated aeronautical communication and navigation system in the L-band, designed to achieve efficient spectrum sharing. We propose a dual-function scheme inspired by non-orthogonal multiple access (NOMA), enabling simultaneous detection of multiple aircraft and transmission of dedicated messages. Specifically, NOMA is utilized to enable double-spectrum sharing, where communication and navigation signals are superimposed in the power domain. Successive interference cancellation (SIC) is employed at the receiver to mitigate inter-function interference. Within this framework, an optimization problem is formulated to maximize the weighted achievable sum rate and effective sensing power, while satisfying rate requirements for message transmission and ensuring a predefined threshold for navigation performance. To address the non-convex problem with highly coupled variables, an alternating optimization (AO) algorithm is proposed, which decouples the original problem into two subproblems: transmit beamforming and power allocation. The successive rank-one constraint relaxation (SROCR) method is applied to handle non-convex rank-one constraints. Numerical results demonstrate that the proposed scheme significantly outperforms conventional benchmark strategies, highlighting its effectiveness in enhancing spectrum utilization and system performance.