An uplink phase synchronization scheme for moving space craft based transmit antenna arraying in deep space communications

Abstract

Aiming at space craft with different orbits and different movement patterns, a system model in deep space communications is established. Based on this model, a transmit antenna arraying scheme according to periodical downlink time-scale signals is proposed. In particularly, a space craft transmits time-scale signals periodically to earth stations, and then distributed target earth stations adjust their delays for uplink transmission according to these signals by typical prediction-based schemes, such as first-order and second-order polynomial as well as improved polynomial based schemes. In this way, phases of the uplink signals can be synchronized on the space craft and coherent reception can be realized. Based on the communication system between lunar orbiter and earth stations, simulation results show the outstanding performance of our proposed schemes: When no prediction schemes are adopted, the composite signals received by lunar orbiter have serious performance loss. In contrast, the received composite signal can meet the accuracy requirements of phase difference for coherence reception with the prediction-based adjustment schemes, and the maximum power gain can be obtained. These schemes can greatly improve the reliability of deep space communications. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.