Cellular assisted sidelink discovery
Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may support cellular communications (e.g., Uu signaling) in a first frequency range and may support sidelink communications in a second, higher frequency range. To reduce the processing overhead and latency involved in sidelink discovery in the second frequency range, the UE may use Uu signaling in the first frequency range to assist with the sidelink discovery. For example, the UE may determine, based on a configuration, an uplink message supporting UE detection in the first frequency range to support sidelink discovery. The UE may monitor for the uplink message in the first frequency range and may detect a second UE based on the monitoring. The UEs may establish a sidelink connection for sidelink communications in the second frequency range based on the detection of the second UE in the first frequency range.
1 . A method for wireless communications at a first user equipment (UE), comprising:
determining, based at least in part on a configuration of the first UE, an uplink message supporting UE detection for sidelink discovery, wherein the configuration indicates a time domain resource for the uplink message;
monitoring for the uplink message in a first frequency range according to the time domain resource;
detecting a second UE in accordance with receiving, at the first UE and over the time domain resource, the uplink message from the second UE based at least in part on the monitoring; and
communicating a sidelink message with the second UE in a second frequency range different from the first frequency range based at least in part on detecting the second UE.
2 . The method of claim 1 , further comprising:
receiving a configuration message indicating the uplink message supporting UE detection for sidelink discovery, the determining based at least in part on the configuration message.
3 . The method of claim 2 , wherein the configuration message comprises a flag indicating that the uplink message supports UE detection for sidelink discovery, a time domain resource configuration for the uplink message that indicates the time domain resource, a frequency domain resource configuration for the uplink message, a signal generation configuration for the uplink message, a detection threshold for detecting the uplink message, or a combination thereof.
4 . The method of claim 2 , wherein the configuration message comprises a radio resource control configuration message.
5 . The method of claim 1 , wherein the first UE is pre-configured with the configuration of the first UE indicating the uplink message supporting UE detection for sidelink discovery.
6 . The method of claim 5 , wherein the configuration of the first UE indicates that the uplink message supports UE detection for sidelink discovery, a time domain resource configuration for the uplink message that indicates the time domain resource, a frequency domain resource configuration for the uplink message, a signal generation configuration for the uplink message, a detection threshold for detecting the uplink message, or a combination thereof.
7 . The method of claim 1 , further comprising:
determining that the uplink message corresponds to the second UE based at least in part on a UE-specific configuration for the uplink message supporting UE detection for sidelink discovery.
8 . The method of claim 1 , further comprising:
determining that the uplink message corresponds to at least one UE of a plurality of UEs based at least in part on a common configuration for the plurality of UEs for the uplink message supporting UE detection for sidelink discovery, the plurality of UEs comprising at least the second UE.
9 . The method of claim 1 , further comprising:
triggering a sidelink discovery procedure in the second frequency range based at least in part on detecting the second UE; and
establishing a sidelink connection with the second UE based at least in part on the sidelink discovery procedure, the sidelink message being communicated with the second UE via the established sidelink connection.
10 . The method of claim 9 , further comprising:
detecting the uplink message using a first communication beam in the first frequency range based at least in part on the monitoring; and
performing a beam sweeping procedure using a set of second communication beams in the second frequency range based at least in part on the triggered sidelink discovery procedure, the first communication beam comprising a first beam width that is greater than each beam width for the set of second communication beams.
11 . The method of claim 9 , the establishing the sidelink connection with the second UE comprising:
transmitting a sidelink connection request to the second UE based at least in part on detecting the second UE; and
receiving a sidelink connection response from the second UE in response to the sidelink connection request.
12 . The method of claim 9 , the establishing the sidelink connection with the second UE comprising:
transmitting a connection request indicating the second UE based at least in part on detecting the second UE; and
receiving a connection response indicating the second UE in response to the connection request.
13 . The method of claim 1 , the monitoring comprising:
detecting the uplink message based at least in part on a signal metric for the uplink message satisfying a signal metric threshold, the second UE being detected based at least in part on detecting the uplink message.
14 . The method of claim 13 , wherein the signal metric comprises a reference signal received power, a signal-to-noise ratio, a received signal strength indicator, or a combination thereof.
15 . The method of claim 1 , further comprising:
monitoring for an additional uplink message in the first frequency range, the monitoring for the uplink message and the monitoring for the additional uplink message being based at least in part on a configured time domain pattern for at least the uplink message and the additional uplink message.
16 . The method of claim 1 , wherein the uplink message comprises a sounding reference signal, a random access preamble, a physical uplink shared channel message, a physical uplink control channel message, an uplink demodulation reference signal, or a combination thereof.
17 . The method of claim 1 , wherein:
the first UE and the second UE support Uu communications in the first frequency range; and
the first UE and the second UE support sidelink communications in the second frequency range.
18 . The method of claim 1 , wherein:
the first frequency range comprises Frequency Range 1 (FR1); and
the second frequency range comprises Frequency Range 2 (FR2).
19 . An apparatus for wireless communications at a first user equipment (UE), comprising:
one or more memories; and
one or more processors coupled with the one or more memories and configured to cause the first UE to:
determine, based at least in part on a configuration of the first UE, an uplink message that supports UE detection for sidelink discovery, wherein the configuration indicates a time domain resource for the uplink message;
monitor for the uplink message in a first frequency range according to the time domain resource;
detect a second UE in accordance with a reception, at the first UE and over the time domain resource, of the uplink message from the second UE based at least in part on the monitored first frequency range; and
communicate a sidelink message with the second UE in a second frequency range different from the first frequency range based at least in part on the detection of the second UE.
20 . The apparatus of claim 19 , further comprising:
an antenna, the one or more processors further configured to cause the first UE to:
receive, via the antenna, a configuration message that indicates the uplink message supports UE detection for sidelink discovery, the determination based at least in part on the configuration message.
21 . The apparatus of claim 20 , wherein the configuration message comprises a flag that indicates the uplink message supports UE detection for sidelink discovery, a time domain resource configuration for the uplink message that indicates the time domain resource, a frequency domain resource configuration for the uplink message, a signal generation configuration for the uplink message, a detection threshold for detection of the uplink message, or a combination thereof.
22 . The apparatus of claim 19 , wherein the first UE is pre-configured with the configuration of the first UE that indicates the uplink message supports UE detection for sidelink discovery.
23 . The apparatus of claim 22 , wherein the configuration of the first UE indicates that the uplink message supports UE detection for sidelink discovery, a time domain resource configuration for the uplink message that indicates the time domain resource, a frequency domain resource configuration for the uplink message, a signal generation configuration for the uplink message, a detection threshold for detection of the uplink message, or a combination thereof.
24 . The apparatus of claim 19 , wherein the one or more processors are further configured to cause the first UE to:
determine that the uplink message corresponds to the second UE based at least in part on a UE-specific configuration for the uplink message that supports UE detection for sidelink discovery.
25 . The apparatus of claim 19 , wherein the one or more processors are further configured to cause the first UE to:
determine that the uplink message corresponds to at least one UE of a plurality of UEs based at least in part on a common configuration for the plurality of UEs for the uplink message that supports UE detection for sidelink discovery, wherein the plurality of UEs comprises at least the second UE.
26 . The apparatus of claim 19 , wherein the one or more processors are further configured to cause the first UE to:
trigger a sidelink discovery procedure in the second frequency range based at least in part on the detection of the second UE; and
establish a sidelink connection with the second UE based at least in part on the sidelink discovery procedure, wherein the sidelink message is communicated with the second UE via the established sidelink connection.
27 . A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by one or more processors to cause the first UE to:
determine, based at least in part on a configuration of the first UE, an uplink message supporting UE detection for sidelink discovery, wherein the configuration indicates a time domain resource for the uplink message;
monitor for the uplink message in a first frequency range according to the time domain resource;
detect a second UE in accordance with a reception, at the first UE and over the time domain resource, of the uplink message from the second UE based at least in part on the monitoring; and
communicate a sidelink message with the second UE in a second frequency range different from the first frequency range based at least in part on the detection of the second UE.
28 . The non-transitory computer-readable medium of claim 27 , wherein the instructions are further executable by the one or more processors to cause the first UE to:
receive a configuration message indicating the uplink message supporting UE detection for sidelink discovery, the determining based at least in part on the configuration message.
29 . The non-transitory computer-readable medium of claim 28 , wherein the configuration message comprises a flag indicating that the uplink message supports UE detection for sidelink discovery, a time domain resource configuration for the uplink message that indicates the time domain resource, a frequency domain resource configuration for the uplink message, a signal generation configuration for the uplink message, a detection threshold for detecting the uplink message, or a combination thereof.
30 . An apparatus for wireless communications at a first user equipment (UE), comprising:
means for determining, based at least in part on a configuration of the first UE, an uplink message supporting UE detection for sidelink discovery, wherein the configuration indicates a time domain resource for the uplink message;
means for monitoring for the uplink message in a first frequency range according to the time domain resource;
means for detecting a second UE in accordance with a reception, at the first UE and over the time domain resource, of the uplink message from the second UE based at least in part on the monitoring; and
means for communicating a sidelink message with the second UE in a second frequency range different from the first frequency range based at least in part on the detection of the second UE.