Velocity-adaptive Beam Handover for LEO Satellite Communications: A Collaborative Decision Strategy Combining DDQN and TOPSIS

As a vital component of 6G networks, low Earth orbit (LEO) satellite communications face frequent beam handover caused by high-speed movement while achieving wide-area coverage. To address this, a velocity-adaptive beam handover algorithm is proposed. For mobile terminals (MTs) in different scenarios, the algorithm dynamically adapts to their velocities by selecting either an improved double deep Q-Network (DDQN) or the technique for order preference by similarity to an ideal solution (TOPSIS) to achieve global optimal decision-making. This approach ensures real-time performance while comprehensively evaluating beam quality. Furthermore, it adaptively adjusts the hysteresis parameter (HP) to optimize handover decisions. In addition, the algorithm constructs utility functions and weight allocation mechanisms to meet the diverse Quality of Service (QoS) requirements of different services. Simulation results demonstrate that the proposed algorithm achieves superior performance. Compared with existing algorithms, this algorithm effectively suppresses ping-pong handovers, thereby reducing the number of handovers and handover failures while improving user throughput.