1. School of Geomatics, Liaoning Technical University, Fuxin 123000, China
2. Satellite Laser Ranging National Observation and Research Station, Chinese Academy of Surveying and Mapping, Beijing 100094, China
3. German Research Centre for Geosciences, Helmholtz Centre Potsdam, Space Geodetic Techniques, 14473 Potsdam, Germany
4. Institut für Geodäsie und Geoinformationstechnik, Technische Universitat Berlin, 10553 Berlin, Germany