jgg     2012 32 (4):  79-82    ISSN: 0412-1961  CN: 21-1139/TG RESEARCH ON DATUM DETERMINATION IN PARAMETER ESTIMATION OF GNSS NETWORK Xiao Yugang;Liu Hongfei ;and Wang Zheng School of Geodesy and Geomatics，Wuhan University，Wuhan 430079 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null