Robust two-stage Kalman filter scheme for compensating abrupt and gradual Doppler shifts in establishment and maintenance of LEO-LEO laser inter-satellite links.

Abstract

A robust two-stage Kalman filter (KF) scheme is proposed to address the challenges of Doppler shifts in LEO-LEO coherent laser inter-satellite links (LISLs). A dual-satellite LEO-LEO LISL model is developed through rotational normalization to analyze the necessity of compensating for abrupt shifts in link establishment and gradual shifts in link maintenance. The proposed scheme utilizes a two-stage KF with two sets of specific parameter states to realize cascaded rough and fine compensations. In the 60 Gbaud simulation system with cosmic channel, the proposed scheme can compensate for a 10 GHz abrupt Doppler shift, along with gradual Doppler shift drift rates of 151.73 MHz/s, at an optical signal-to-noise ratio of 18 dB.