Beam training of a receiver device
A method and other arrangements are disclosed for beam training of a receiver device configured for beamforming reception from a transmitter. The beam training is based on a plurality of multi-arm reception beams. The method includes performing signal strength measurements for each of the multi-arm reception beams, selecting one of the multi-arm reception beams based on the signal strength measurements, nulling one arm for the multi-arm reception beam, and updating the signal strength measurements by performing signal strength measurements for the multi-arm reception beam with the arm nulled. The method also includes iteratively repeating the selecting, nulling, updating and determining steps so as to obtain further signal strength measurements for multi-arm reception beams with additional arms nulled, selecting a reception beam, based on the signal strength measurements before and after the updates and selecting a reception beam based on the signal strength measurements before and after the updates.
1 . A method for beam training of a receiver device configured for beamforming reception from a transmitter, wherein the beam training is based on a plurality of multi-arm reception beams, the method comprising:
performing signal strength measurements for each of the multi-arm reception beams;
selecting one of the multi-arm reception beams based on the signal strength measurements;
nulling one arm for the selected multi-arm reception beam;
updating the signal strength measurements by performing signal strength measurements for the selected multi-arm reception beam with the arm nulled;
determining a difference between signal strength measurements before and after the update;
iteratively repeating the selecting, nulling, updating and determining steps, in order to obtain further signal strength measurements for multi-arm reception beams with additional arms nulled;
stopping the iteration when a stopping criterion is met, the stopping criterion comprising one or more of:
a nulled arm corresponding to an arm signal strength that exceeds a first threshold value; and
none of the multi-arm reception beams having a signal strength that exceeds a second threshold value; and
selecting a reception beam, based on the determined differences between signal strength measurements before and after the updates.
2 . The method of claim 1 , wherein selecting one of the multi-arm reception beams based on the signal strength measurements comprises selecting a multi-arm reception beam with a highest signal strength among the multi-arm reception beams.
3 . The method of claim 1 , wherein nulling one arm for the selected multi-arm reception beam comprises nulling a randomly picked arm that has not yet been nulled.
4 . The method of claim 1 , wherein nulling one arm for the selected multi-arm reception beam comprises nulling an arm with a highest arm signal strength among arms that have not yet been nulled obtained during a previous beam training session.
5 . The method of claim 1 , wherein nulling one arm for the selected multi-arm reception beam comprises nulling an arm with a highest statistical signal strength among arms that have not yet been nulled according to an applied channel model.
6 . The method of claim 1 , wherein selecting the reception beam based on the determined differences comprises selecting the reception beam as an arm that corresponds to a highest difference among arms nulled during signal strength measurements.
7 . The method of claim 1 , wherein the method is performed for each of a plurality of transmission beams of the transmitter.
8 . An apparatus for beam training of a receiver device configured for beamforming reception from a transmitter, the beam training being based on a plurality of multi-arm reception beams, the apparatus comprising controlling circuitry configured to cause:
performance of signal strength measurements for each of the multi-arm reception beams;
selection of one of the multi-arm reception beams based on the signal strength measurements;
nulling of one arm for the selected multi-arm reception beam;
updating of the signal strength measurements by performance of signal strength measurements for the selected multi-arm reception beam with the arm nulled;
determination of a difference between signal strength measurements before and after the update;
iterative repetition of the selecting, nulling, updating and determination steps, in order to obtain further signal strength measurements for multi-arm reception beams with additional arms nulled; and
stopping the iteration responsive to a stopping criterion being met, the stopping criterion comprising one or more of:
a nulled arm corresponding to an arm signal strength that exceeds a first threshold value; and
none of the multi-arm reception beams having a signal strength that exceeds a second threshold value; and
selection of a reception beam, based on the signal strength measurements before and after the updates.
9 . The apparatus of claim 8 , wherein the controlling circuitry is configured to cause selection of one of the multi-arm reception beams based on the signal strength measurements by causing selection of a multi-arm reception beam with a highest signal strength among the multi-arm reception beams.
10 . The apparatus of claim 8 , wherein the controlling circuitry is configured to cause nulling of one arm for the selected multi-arm reception beam by causing nulling of a randomly picked arm that has not yet been nulled.
11 . The apparatus of claim 8 , wherein the controlling circuitry is configured to cause nulling of one arm for the selected multi-arm reception beam by casing nulling of an arm with a highest arm signal strength among arms that have not yet been nulled obtained during a previous beam training session.
12 . The apparatus of claim 8 , wherein the controlling circuitry is configured to cause nulling of one arm for the multi-arm reception beam by casing nulling of an arm with a highest statistical signal strength among arms that have not yet been nulled according to an applied channel model.
13 . The apparatus of claim 8 , wherein the controlling circuitry is configured to cause selection of the reception beam based on the determined differences by causing selection of the reception beam as an arm that corresponds to a highest difference among arms nulled during signal strength measurements.
14 . The apparatus of claim 8 , wherein a plurality of transmission beams are transmitted by the transmitter, and wherein the controlling circuitry is configured to cause the performance of signal strength measurements, selection of the one of the multi-arm reception beams, nulling of the one arm, updating of the signal strength measurements, determination of the difference, iterative repetition of the selecting, nulling, updating and determination, stopping the iteration and selection of the reception beam, for each of the plurality of transmission beams.
15 . The apparatus of claim 8 , wherein the apparatus is comprised in a receiver device.
16 . The apparatus of claim 8 , wherein the apparatus is comprised in a user equipment.