Patent ID: 9655107
Date: 2017-05-16
CPC Classifications: H04B,H04J,H04L,H04W

Claim:
1. A method for reducing channel estimation overhead, the method comprising: at an eNodeB that provides a cell: determining an optimal signal subspace containing the plurality of active UEs in the cell using the beamforming vector matrix; transmitting a beam formed reference signal to the determined optimal signal subspace; determining that a UE of the plurality of active UEs in the cell has moved out of the optimal signal subspace; recalculating the beamforming vector matrix for the plurality of active UEs including the UE of the plurality of active UEs in the cell; transmitting a second beam formed reference signal to the UE of the plurality of active UEs in the cell using the recalculated beamforming reference matrix, the second beam formed reference signal being outside the optimal signal subspace; receiving a projected channel from the UE of the plurality of active UEs in the cell, the projected channel calculated by the UE of the plurality of active UEs in the cell based upon the second beam formed reference signal; and transforming a codebook and aligning codewords with a channel direction of the received projected channel.