Patent ID: 9054415
Filing Date: 2015-06-09
Classification: H01Q,H04B

Abstract:
1. A method for handling a relative phase error between radio chains in a radio base station having at least two radio chains, said radio base station being configured to precode information symbols using a precoding matrix for multi-antenna transmission to a number of user equipment terminals, said method comprising: compiling precoding matrix statistics based on feedback information that is received from at least one of said user equipment terminals, that is representative of one or more precoding matrix indices (PMI), and that is collected over time to represent phase coherency between at least two of said radio chains; detecting a relative phase error between at least two of said radio chains, and estimating a phase compensation value for at least one of said radio chains, based on said precoding matrix statistics and pre-established precoding matrix reference information, wherein the pre-established precoding matrix reference information represents, for each of a number of relative phase errors, how frequent each of a number of precoding matrix indices is assumed to be used for indicating preferred precoding matrix; and compensating for said detected relative phase error by applying a phase compensation for at least one of said radio chains based on said estimated phase compensation value.