Transponder signaling for localization on higher bands
Methods, systems, and devices for wireless communications are described. Some wireless networks may maintain up-to-date location information for the UE by periodically determining the location the UE using a low power transponding mechanism while the UE is in an inactive state. The UE may monitor a first beam to receive one or more transponder search signals during one or more transponder occasions, and between paging attempts from one or more of the base stations of the network. The UE may receive the one or more transponder search signals, and may transmit a transponder response message to a base station including a UE identifier associated with the inactive state. The base station may receive the transponder response message, and may conduct various location measurements for the UE using the transponder response.
1 . A method for wireless communications at a base station, comprising:
identifying a transition of a user equipment (UE) from a connected state to an inactive state;
transmitting, during a first transponder occasion, a transponder search message that comprises an identifier associated with a notification area of the base station via a first beam;
receiving a first transponder response message comprising a second identifier associated with the UE;
determining a location of the UE based at least in part on the first transponder response message;
identifying a first periodicity for a plurality of transponder occasions associated with the notification area, the plurality of transponder occasions comprising the first transponder occasion; and
transmitting the transponder search message in each of the plurality of transponder occasions in accordance with the first periodicity.
2 . The method of claim 1 , further comprising:
identifying a second periodicity for transmitting one or more paging messages during a plurality of paging occasions, wherein the second periodicity for transmitting the one or more paging messages is longer than the first periodicity for transmitting the transponder search message;
transmitting the one or more paging messages based at least in part on the second periodicity; and
receiving, during a first paging occasion, an indication of the location of the UE based at least in part on the first transponder response message.
3 . The method of claim 1 , wherein the first periodicity is based at least in part on a mobility profile of the UE, power consumption of the UE, or both.
4 . The method of claim 1 , wherein determining the location of the UE further comprises:
determining an angle of arrival of the first beam associated with receiving the first transponder response message; and
determining a relative direction of the UE with respect to the base station based at least in part on the angle of arrival of the first beam.
5 . The method of claim 1 , further comprising:
determining a round-trip time between transmitting the transponder search message and receiving the first transponder response message; and
determining a relative distance of the UE with respect to the base station based at least in part on the round-trip time.
6 . The method of claim 1 , wherein the transponder search message is associated with a correlation property for detection using an analog correlation circuit.
7 . The method of claim 1 , further comprising:
identifying the first beam based at least in part on a prior communication with the UE.
8 . The method of claim 1 , further comprising:
identifying the first beam based at least in part on a prior communication of a second base station with the UE or a last known location of the UE.
9 . The method of claim 1 , wherein the second identifier of the first transponder response message comprises a radio network temporary identifier associated with the inactive state of the UE.
10 . The method of claim 9 , further comprising:
receiving the first transponder response message multiplexed with one or more other transponder response messages from one or more additional UEs based at least in part on the radio network temporary identifier.
11 . The method of claim 1 , wherein the first transponder response message comprises one or more data fields for indicating one or more measurements associated with the UE, the one or more measurements comprising a UE transmission power level, timing and frequency parameters, battery status of the UE, user interaction history, operating temperature, or any combination thereof.
12 . The method of claim 1 , further comprising:
monitoring for the first transponder response message at a predetermined offset from the transponder search message.
13 . An apparatus for wireless communications at a base station, comprising:
one or more processors; and
one or more memories coupled with the one or more processors, the one or more memories comprising instructions executable by the one or more processors to cause the apparatus to:
identify a transition of a user equipment (UE) from a connected state to an inactive state;
transmit, during a first transponder occasion, a transponder search message that comprises an identifier associated with a notification area of the base station via a first beam;
receive a first transponder response message comprising a second identifier associated with the UE;
determine a location of the UE based at least in part on the first transponder response message;
identify a first periodicity for a plurality of transponder occasions associated with the notification area, the plurality of transponder occasions comprising the first transponder occasion; and
transmit the transponder search message in each of the plurality of transponder occasions in accordance with the first periodicity.
14 . The apparatus of claim 13 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
identify a second periodicity for transmitting one or more paging messages during a plurality of paging occasions, wherein the second periodicity for transmitting the one or more paging messages is longer than the first periodicity for transmitting the transponder search message;
transmit the one or more paging messages based at least in part on the second periodicity; and
receive, during a first paging occasion, an indication of the location of the UE based at least in part on the first transponder response message.
15 . The apparatus of claim 13 , wherein the first periodicity is based at least in part on a mobility profile of the UE, power consumption of the UE, or both.
16 . The apparatus of claim 13 , wherein the instructions to determine the location of the UE are further executable by the one or more processors to cause the apparatus to:
determine an angle of arrival of the first beam associated with receiving the first transponder response message; and
determine a relative direction of the UE with respect to the base station based at least in part on the angle of arrival of the first beam.
17 . The apparatus of claim 13 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
determine a round-trip time between transmitting the transponder search message and receiving the first transponder response message; and
determine a relative distance of the UE with respect to the base station based at least in part on the round-trip time.
18 . The apparatus of claim 13 , wherein the transponder search message is associated with a correlation property for detection using an analog correlation circuit.