Non-stationary MAB based access method for heterogeneous users in LEO satellite systems

Provided that both throughput-sensitive and delay-sensitive users access the low earth orbit (LEO) satellite system simultaneously, a non-orthogonal multiple access (NOMA) access method using non-stationary multi-armed bandit (MAB) was proposed to enhance the system spectral efficiency and access flexibility for the heterogeneous users. Firstly, a utility function was established to jointly consider the age of information (AoI) of delay-sensitive users and the throughput requirements of throughput-sensitive users. Then, an optimization problem was formulated to maximize the joint utility function, while satisfying the constraints of rate thresholds and packet buffering time. Since the traditional convex optimization methods couldn’t solve this problem, by using the beamforming to suppress the inter-group interference, a dynamic access scheme based on the non-stationary MAB was proposed to realize the intelligent pairing, scheduling, and reliable access for the heterogeneous users. Finally, computer simulations demonstrate the reliability and superiority of the proposed method, and reveal the impact of discount factor and packet buffer threshold on the system performance.