Rotational alignment for multiple-input multiple-output devices

1 . A method for wireless communication at a first wireless device, comprising:

transmitting a first capability message indicating that the first wireless device supports a panel rotation capability;

receiving a second capability message indicating that a second wireless device supports the panel rotation capability, the panel rotation capability associated with a capability of a respective wireless device to adjust an angular rotation of an antenna panel of the respective wireless device;

receiving a configuration message that comprises a panel rotation procedure configuration based at least in part on the panel rotation capability, wherein the panel rotation procedure configuration comprises scheduling information for one or more reference signals;

receiving, via a first set of two or more antenna elements of a plurality of antenna elements of a first antenna panel of the first wireless device, a reference signal of the one or more reference signals based at least in part on the panel rotation procedure configuration, wherein the reference signal is transmitted by a central antenna element of a second antenna panel of the second wireless device;

adjusting, based at least in part on measurements of the reference signal at the first set of two or more antenna elements, an angular rotation of the first antenna panel of the first wireless device to modify a respective distance between each of the first set of two or more antenna elements of the first antenna panel relative to the central antenna element of the second antenna panel of the second wireless device; and

transmitting, to the second wireless device, a message indicating alignment feedback information for the first antenna panel and the second antenna panel.

2 . The method of claim 1 , further comprising:

receiving, via a second set of two or more antenna elements of the plurality of antenna elements of the first antenna panel, a second reference signal transmitted by the central antenna element of the second wireless device, wherein adjusting the angular rotation of the first antenna panel further comprises:

adjusting, based at least in part on second measurements of the second reference signal at the second set of two or more antenna elements, the angular rotation of the first antenna panel to modify a respective second distance between each of the second set of two or more antenna elements of the first antenna panel relative to the central antenna element of the second antenna panel.

3 . The method of claim 1 , wherein transmitting the message comprises:

transmitting, via the alignment feedback information, an indication that the first antenna panel is perpendicular with respect to a line connecting a center of the first antenna panel and a center of the second antenna panel.

4 . The method of claim 1 , wherein transmitting the message comprises:

transmitting, via the alignment feedback information, an indication that the first antenna panel is not perpendicular with respect to a line connecting a center of the first antenna panel and a center of the second antenna panel.

5 . The method of claim 4 , further comprising:

receiving, via the first set of two or more antenna elements of the plurality of antenna elements of the first antenna panel, a second reference signal transmitted by the central antenna element of the second wireless device based at least in part on the alignment feedback information; and

adjusting, based at least in part on second measurements of the second reference signal at the first set of two or more antenna elements, the angular rotation of the first antenna panel to further modify the respective distance between each of the first set of two or more antenna elements of the first antenna panel relative to the central antenna element of the second antenna panel.

6 . The method of claim 1 , wherein transmitting the message comprises:

transmitting, via the alignment feedback information, an indication that a difference between a first phase measurement at a first antenna element of the first set of two or more antenna elements and a second phase measurement at a second antenna element of the first set of two or more antenna elements satisfies a threshold.

7 . The method of claim 6 , wherein:

the first phase measurement is based at least in part on a plurality of first phase measurements of the reference signal received across one or more frequencies, across a set of one or more first antenna elements of the first antenna panel, or both, the set of one or more first antenna elements comprising the first antenna element of the first set of two or more antenna elements; and

the second phase measurement is based at least in part on a plurality of second phase measurements of the reference signal received across the one or more frequencies, across a set of one or more second antenna elements of the first antenna panel, or both, the set of one or more second antenna elements comprising the second antenna element of the first set of two or more antenna elements.

8 . The method of claim 6 , further comprising:

comparing the first phase measurement, the second phase measurement, or both to a phase tolerance threshold, wherein adjusting the angular rotation of the first antenna panel is based at least in part on the first phase measurement, the second phase measurement, or both satisfying the phase tolerance threshold.

9 . The method of claim 1 , further comprising:

receiving, via at least a first non-central antenna element of the plurality of antenna elements of the first antenna panel, one or more reference signals transmitted by one or more second non-central antenna elements of the second antenna panel of the second wireless device;

determining, based at least in part on the one or more reference signals, a first angle between the first non-central antenna element and a first axis of the first antenna panel and a second angle between a second non-central antenna element of the one or more second non-central antenna elements of the second antenna panel and a second axis of the second antenna panel that is parallel to the first axis, wherein the first non-central antenna element corresponds to the second non-central antenna element; and

rotating the first antenna panel around a central point of the first antenna panel to adjust an angular difference between the first angle and the second angle.

10 . The method of claim 9 , further comprising:

transmitting, to the second wireless device, a second message comprising second alignment feedback information that indicates whether the angular difference between the first angle and the second angle is less than a threshold angular difference.

11 . The method of claim 9 , wherein:

each antenna element of the plurality of antenna elements of the first antenna panel at the first wireless device corresponds to a respective second antenna element of a plurality of second antenna elements of the second antenna panel at the second wireless device; and

rotating the first antenna panel includes modifying one or more angular differences between each pair of a respective first antenna element at the first wireless device and a respective second antenna element at the second wireless device.

12 . The method of claim 1 , further comprising:

transmitting, via a central antenna element of the first antenna panel at the first wireless device, a second reference signal to the second wireless device; and

receiving, from the second wireless device, a second message indicating second alignment feedback information for the first antenna panel and the second antenna panel based at least in part on the second reference signal and a panel rotation procedure performed by the second wireless device.

13 . The method of claim 1 , wherein a first distance between two antenna elements of the first set of two or more antenna elements is greater than or equal to a second distance between any other antenna elements of the plurality of antenna elements within the first antenna panel.

14 . The method of claim 1 , wherein at least a subset of the plurality of antenna elements are disposed in a circular shape or a rectangular shape around a central antenna element of the first antenna panel.

15 . The method of claim 1 , wherein the first wireless device and the second wireless device support orbital angular momentum communications, line-of-sight multiple-input multiple-output communications, or both.

16 . A method for wireless communication at a second wireless device, comprising:

transmitting a first capability message indicating that the second wireless device supports a panel rotation capability;

receiving a second capability message indicating that a first wireless device supports the panel rotation capability, the panel rotation capability associated with a capability of a respective wireless device to adjust an angular rotation of an antenna panel of the respective wireless device;

communicating, with the first wireless device, a panel rotation procedure configuration based at least in part on the panel rotation capability, wherein the panel rotation procedure configuration comprises scheduling information for one or more reference signals;

transmitting a reference signal of the one or more reference signals via a central antenna element of a second antenna panel of the second wireless device based at least in part on the panel rotation procedure configuration; and

receiving, by the second wireless device, a message indicating alignment feedback information for the second antenna panel of the second wireless device and a first antenna panel of the first wireless device based at least in part on the reference signal.

17 . The method of claim 16 , further comprising:

transmitting, via the central antenna element of the second antenna panel of the second wireless device, a second reference signal.

18 . The method of claim 17 , wherein receiving the message comprises:

receiving, via the alignment feedback information based at least in part on the reference signal, an indication that the first antenna panel is not perpendicular with respect to a line connecting a center of the first antenna panel and a center of the second antenna panel, wherein transmitting the second reference signal is based at least in part on the indication that the first antenna panel is not perpendicular to the line.

19 . The method of claim 16 , wherein receiving the message comprises:

receiving, via the alignment feedback information based at least in part on the reference signal, an indication that the first antenna panel is perpendicular to a line connecting a center of the first antenna panel and a center of the second antenna panel.

20 . The method of claim 16 , wherein receiving the message comprises:

receiving, via the alignment feedback information, an indication that a difference between a first phase measurement at a first antenna element of the first antenna panel of the first wireless device and a second phase measurement at a second antenna element of the first antenna panel of the first wireless device satisfies a threshold.

21 . The method of claim 16 , further comprising:

transmitting, via one or more second non-central antenna elements of the second antenna panel, one or more reference signals, wherein each of the one or more second non-central antenna elements corresponds to a respective first non-central antenna element of a plurality of first non-central antenna elements of the first antenna panel at the first wireless device; and

receiving, by the second wireless device, a second message comprising second alignment feedback information that indicates whether an angular difference between a first angle associated with a first non-central antenna element of the plurality of first non-central antenna elements and a second angle associated with a second non-central antenna element of the one or more second non-central antenna elements is less than a threshold angular difference, wherein the first angle is between the first non-central antenna element and a first axis of the first antenna panel and the second angle is between the second non-central antenna element of the second antenna panel and a second axis of the second antenna panel that is parallel to the first axis, and wherein the first non-central antenna element corresponds to the second non-central antenna element.

22 . The method of claim 16 , further comprising:

receiving, via a set of two or more antenna elements of the second antenna panel of the second wireless device, a second reference signal transmitted by a central antenna element of the first antenna panel of the first wireless device;

adjusting, based at least in part on measurements of the second reference signal at the set of two or more antenna elements, an angular rotation of the second antenna panel to modify a respective distance between each of the set of two or more antenna elements of the second antenna panel relative to the central antenna element of the first antenna panel; and

transmitting, to the first wireless device, a second message indicating second alignment feedback information for the first antenna panel and the second antenna panel based at least in part on adjusting the angular rotation of the second antenna panel.

23 . An apparatus for wireless communication at a first wireless device, comprising:

one or more processors;

one or more memories coupled with the one or more processors; and

instructions stored in the one or more memories and executable by the one or more processors to cause the apparatus to:

transmit a first capability message indicating that the first wireless device supports a panel rotation capability;

receive a second capability message indicating that a second wireless device supports the panel rotation capability, the panel rotation capability associated with a capability of a respective wireless device to adjust an angular rotation of an antenna panel of the respective wireless device;

receive a configuration message that comprises a panel rotation procedure configuration based at least in part on the panel rotation capability, wherein the panel rotation procedure configuration comprises scheduling information for one or more reference signals;

receive, via a first set of two or more antenna elements of a plurality of antenna elements of a first antenna panel of the first wireless device, a reference signal of the one or more reference signals based at least in part on the panel rotation procedure configuration, wherein the reference signal is transmitted by a central antenna element of a second antenna panel of the second wireless device;

adjust, based at least in part on measurements of the reference signal at the first set of two or more antenna elements, an angular rotation of the first antenna panel of the first wireless device to modify a respective distance between each of the first set of two or more antenna elements of the first antenna panel relative to the central antenna element of the second antenna panel of the second wireless device; and

transmit, to the second wireless device, a message indicating alignment feedback information for the first antenna panel and the second antenna panel.

24 . The apparatus of claim 23 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:

receive a configuration message that comprises a panel rotation procedure configuration based at least in part on the panel rotation capability, wherein receiving the reference signal is based at least in part on the panel rotation procedure configuration.

25 . An apparatus for wireless communication at a second wireless device, comprising:

one or more processors;

one or more memories coupled with the one or more processors; and

instructions stored in the one or more memories and executable by the one or more processors to cause the apparatus to:

transmit a first capability message indicating that the second wireless device supports a panel rotation capability;

receive a second capability message indicating that a first wireless device supports the panel rotation capability, the panel rotation capability associated with a capability of a respective wireless device to adjust an angular rotation of an antenna panel of the respective wireless device;

communicate, with the first wireless device, a panel rotation procedure configuration based at least in part on the panel rotation capability, wherein the panel rotation procedure configuration comprises scheduling information for one or more reference signals;

transmit a reference signal of the one or more reference signals via a central antenna element of a second antenna panel of the second wireless device based at least in part on the panel rotation procedure configuration; and

receive, by the second wireless device, a message indicating alignment feedback information for the second antenna panel of the second wireless device and a first antenna panel of the first wireless device based at least in part on the reference signal.