The Improvement of SPGD Algorithm Convergence in Satellite-to-Ground Laser Communication Links

The stochastic parallel gradient descent (SPGD) algorithm is a wave-front aberration correction algorithm which can directly optimize the performance metric of the system and can be applied to the channel of medium or strong turbulence. But due to slow convergence the algorithm can not fully meet the wave-front correction real-time requirements of satellite-to-ground laser communication links.Based on conventional SPGD algorithm this paper improves SPGD algorithm from two aspects: changing each iterative time and decreasing the overall iterative number. Simulation results show that algorithm convergence speed has been improved and the response speed of overall system has been improved significantly by using the improved method. Although the improved system will still delay for dynamic wave-front correction, overall speed has been very close to the ideal speed.