Patent ID: 8923366
Filing Date: 2014-12-30
Classification: H04B

Abstract:
1. A method for selecting a pre-coder to be used by a transmitter to pre-code transmit signals in a multiple-input multiple output (MIMO) communications system, comprising: constructing a subset of pre-coders from a predetermined codebook that includes a plurality of pre-coders; cycling through the subset of pre-coders during a cycling period by iteratively selecting individual pre-coders in the subset of pre-coders to be used by the transmitter for pre-coding a reference signal, wherein for each iteratively selected precoder, channel state information is updated based on measurement of the reference signal and periodic measurements of a second reference signal that has not been pre-coded by the transmitter, wherein said cycling through the subset of pre-coders is performed in between consecutive ones of the periodic measurements, and wherein each iteratively selected pre-coder is fed back from the receiver to the transmitter; and adaptively modifying the subset of pre-coders to be cycled through, by adding to the subset one or more suitable pre-coders or deleting from the subset one or more unsuitable pre-coders, based on a predetermined criterion.