Enodeb reference signal reduction

1. An eNodeB (eNB) comprising:

a plurality of antenna ports with a plurality of antenna elements;

subspace identification circuitry coupled with the plurality of antenna elements, the subspace identification circuitry to:

identify, based on feedback information, a plurality of beamforming weights for one or multiple antenna ports wherein a number of the antenna ports is less than a number of the plurality of antenna elements; and

assign a beamforming weight in the plurality of beamforming weights to an antenna in the plurality of antenna elements; and

transmitter circuitry coupled with the subspace identification circuitry, the transmitter circuitry to:

beamform a channel training signal allocated for the one or multiple antenna ports with the assigned beamforming weight; and

transmit an antenna port configuration schedule from the plurality of antenna elements.

2. The eNB of claim 1 , wherein the feedback information is based on downlink sounding, or uplink sounding, or a signal received from a user equipment (UE).

3. The eNB of claim 1 , wherein the antenna port configuration schedule includes an indication of a time period where the beamforming weights will not change.

4. The eNB of claim 1 , wherein:

the feedback information includes a first indication of a magnitude or phase of a first received signal of a first beamformed signal produced with a first beamforming vector and a second indication of a magnitude or phase of a second received signal of a second beamformed signal produced with a second beamforming vector;

the subspace identification circuitry is further to identify a signal subspace that includes the first beamforming vector based at least in part on the first indication, and a null subspace that includes the second beamforming vector based at least in part on the second indication; and

the transmitter circuitry is further to beamform the channel training signal to the signal subspace.

5. The eNB of claim 4 , wherein the magnitude of the first received signal is higher than the magnitude of the second received signal.

6. The eNB of claim 4 , wherein the channel training signal is a first channel training signal and the transmitter circuitry is further to beamform a second channel training signal to only a portion of the null subspace.

7. The eNB of claim 6 , further comprising receiver circuitry coupled with the transmitter circuitry, the receiver circuitry to receive, in response to the transmission of the second channel training signal in the null subspace, a second feedback that includes a third indication of a magnitude or phase of a third received signal of a third beamformed signal produced with a third beamforming vector in the null subspace.

8. The eNB of claim 7 , wherein the signal subspace is a first signal subspace and the subspace identification circuitry is further to identify a second signal subspace based at least in part on the third indication, wherein the second signal subspace includes the third beamforming vector.

9. A method comprising:

identifying, by an eNodeB (eNB), a first signal subspace in a space based at least in part on a first indication of a magnitude or a phase of a first received signal of a first beamforming signal using a first beamforming vector in the first signal subspace, the first signal subspace including the first beamforming vector; and

identifying, by the eNB, a null subspace in the space based at least in part on a second indication of a magnitude or a phase of a second received signal of a second beamforming signal using a second beamforming vector in the null subspace, the null subspace including the second beamforming vector; and

beamforming, from an antenna port of the eNB, a channel training signal to the first signal subspace.

10. The method of claim 9 , further comprising:

receiving, by the eNB after the beamforming of the channel training signal, a third indication of a magnitude or a phase of a third received signal of a third beamforming signal using a third beamforming vector in the null subspace, the null subspace including the third beamforming vector; and

identifying, by the eNB, a second signal subspace based at least in part on the third indication, the second signal subspace including the third beamforming vector.

11. The method of claim 10 , wherein the channel training signal is a first channel training signal and the third indication is based at least in part on beamforming, by the eNB, a second channel training signal to at least a portion of the null subspace.

12. The method of claim 10 , wherein the first indication, second indication, and third indication are received by the eNB from a user equipment (UE).

13. The method of claim 9 , wherein the first signal subspace is based at least in part on a singular value decomposition of the first indication.

14. The method of claim 9 , wherein the magnitude of the first received signal is greater than the magnitude of the second received signal.

15. The method of claim 9 , wherein the antenna port includes a plurality of antenna elements of the eNB.

16. The method of claim 9 , wherein the channel training signal is a channel state information-reference signal (CSI-RS) signal.

17. One or more non-transitory computer-readable media comprising instructions which, when executed by one or more processors of an eNodeB (eNB), cause the eNB to:

identify a first signal subspace in a space based at least in part on a first indication of a magnitude or a phase of a first received signal of a first beamforming signal using a first beamforming vector in the first signal subspace, the first signal subspace including a first beamforming vector;

identify a null subspace in the space based at least in part on a second indication of a magnitude or a phase of a second received signal of a second beamforming signal using a second beamforming vector in the null subspace, the null subspace including the second beamforming vector; and

beamform a channel training signal to the first signal subspace.

18. The one or more non-transitory computer readable media of claim 17 , further comprising instructions to:

obtain, after the beamform of the channel training signal, a third indication of a magnitude or a phase of a third received signal of a third beamforming signal using a third beamforming vector in the null subspace, the null subspace including the third beamforming vector; and

identify a second signal subspace based at least in part on the third indication, the second signal subspace including the third beamforming vector.

19. The one or more non-transitory computer-readable media of claim 17 , wherein the magnitude of the first received signal is greater than the magnitude of the second received signal.

20. An eNodeB comprising:

the one or more non-transitory computer-readable media of claim 17 ; and

one or more processors coupled with the one or more computer-readable media and configured to execute the instructions.