Coverage enhanced reciprocity-based precoding scheme

1. A method performed by a radio node for determining precoding information, the method comprising:

determining channel estimates for at least a channel between the radio node and another device;

determining a plurality of precoding hypotheses based on the channel estimates;

determining a Figure of Merit (FOM) for each of the plurality of precoding hypotheses;

determining the precoding information based on the FOM for each of the plurality of precoding hypotheses;

performing matched filtering of received reference symbols and corresponding known reference symbols;

filtering an output of the matched filtering based on a plurality of precoding hypotheses;

applying a transform to the filtered output for the plurality of precoding hypotheses to produce a plurality of transformed precoding hypotheses;

calculating a FOM for each of the plurality of transformed precoding hypotheses; and

selecting a precoder that maximizes the FOM as the precoding information.

2. The method of claim 1 , wherein the matched filtering is performed with at least one of the group consisting of: a Sounding Reference Signal (SRS), a Random Access Channel(RACH), Demodulation Reference Signals (DMRS), a Channel State Information Reference Signal(CSI-RS), Physical Uplink Control Channel (PUCCH), and DMRS for PUCCH.

3. The method of claim 2 , wherein the matched filtering is performed with the SRS and a Zadoff-Chu sequence inverted.

4. The method of claim 1 , wherein the plurality of precoding hypotheses are chosen from at least one of the group consisting of: a codebook, a Grid of Beams (GoB) codebook, a New Radio (NR) Type 1 codebook, an NR Type 2 codebook, and a subset of any of these codebooks.

5. The method of claim 1 , wherein the transform is chosen from the group consisting of: a Discrete Fourier Transform (DFT), an Inverse DFT, a Discrete Cosine Transform (DCT), and an Inverse DCT.

6. The method of claim 1 , wherein the transform is linear.

7. The method of claim 1 , wherein the FOM is a maximum.

8. The method of claim 7 , wherein the maximum is only performed over a limited range.

9. The method of claim 8 , wherein the limited range is related to at least one of the group consisting of: a cyclic prefix and a delay spread of the channel.

10. The method of claim 1 , wherein the FOM is proportional to an estimated Signal to Noise Ratio (SNR).

11. The method of claim 1 , wherein the radio node is a gNB, and the other device is a wireless device that operates in a NR communication network.

12. The method of claim 1 , wherein the radio node is a gNB.

13. The method of claim 1 , wherein the radio node is a wireless device that operates in a NR communication network.

14. The method of claim 1 , wherein the radio node is a wireless device, and the another device is a gNB.

15. The method of claim 1 , wherein the radio node is a base station.

16. The method of claim 1 , wherein the radio node is a wireless device.

17. A base station for determining precoding information, the base station comprising:

one or more processors; and

memory comprising instructions to cause the base station to:

determine channel estimates for at least a channel between the base station and another device;

determine a plurality of precoding hypotheses based on the channel estimates;

determine a Figure of Merit (FOM), for each of the plurality of precoding hypotheses;

determine the precoding information based on the FOM for each of the plurality of precoding hypotheses;

perform matched filtering of received reference symbols and corresponding known reference symbols;

filter an output of the matched filtering based on a plurality of precoding hypotheses;

apply a transform to the filtered output for the plurality of precoding hypotheses to produce a plurality of transformed precoding hypotheses;

calculate a FOM for each of the plurality of transformed precoding hypotheses; and

select a precoder that maximizes the FOM as the precoding information.

18. A wireless device for determining precoding information, the wireless device comprising:

one or more processors; and

memory comprising instructions to cause the wireless device to:

determine channel estimates for at least a channel between the wireless device and another device;

determine a plurality of precoding hypotheses based on the channel estimates;

determine a Figure of Merit (FOM), for each of the plurality of precoding hypotheses;

determine the precoding information based on the FOM for each of the plurality of precoding hypotheses;

perform matched filtering of received reference symbols and corresponding known reference symbols;

filter an output of the matched filtering based on a plurality of precoding hypotheses;

apply a transform to the filtered output for the plurality of precoding hypotheses to produce a plurality of transformed precoding hypotheses;

calculate a FOM for each of the plurality of transformed precoding hypotheses; and

select a precoder that maximizes the FOM as the precoding information.