User equipment transmit/receive calibration in time division duplexing using assistance information
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a transmit/receive (Tx/Rx) imbalance associated with a user equipment (UE) may be calibrated. For example, in some aspects, the UE may transmit a sounding reference signal (SRS) to an assisting node, which may provide the UE with assistance information indicating a received version of the SRS or an estimated effective channel based on the SRS transmission, which the UE may then use to calculate one or more Tx/Rx imbalance values. Additionally or alternatively, the UE may receive a reference signal from the assisting node and provide feedback to the assisting node, and the assistance information may indicate the one or more Tx/Rx imbalance values to the UE. In either case, the UE may then use the one or more Tx/Rx imbalance values to select a precoder for a transmission to the assisting node.
1 . A user equipment (UE) for wireless communication, comprising:
one or more antennas; and
a processing system that includes one or more processors and one or more memories that store code for the one or more processors, the processing system configured to cause the UE to:
receive, from an assisting node, a first channel state information reference signal (CSI-RS);
transmit, to the assisting node, feedback that indicates the first CSI-RS or an estimate of an effective downlink channel associated with the first CSI-RS;
transmit, to the assisting node, a sounding reference signal (SRS) including one or more first transmit/receive (Tx/Rx) imbalance values that relates to a Tx/Rx mismatch associated with the UE and is in accordance with the feedback;
receive, from the assisting node, one or more second Tx/Rx imbalance values;
receive, from the assisting node, a second CSI-RS;
estimate an effective uplink channel in accordance with a downlink channel estimate associated with the second CSI-RS and in accordance with the one or more second Tx/Rx imbalance values; and
transmit an uplink communication using a precoder associated with the estimated effective uplink channel.
2 . The UE of claim 1 , wherein the processing system is further configured to cause the UE to:
estimate one or more third Tx/Rx imbalance values associated with the assisting node in accordance with the first CSI-RS and information that relates to the Tx/Rx mismatch associated with the UE; and
transmit, to the assisting node, feedback that indicates the estimated one or more third Tx/Rx imbalance values associated with the assisting node.
3 . The UE of claim 1 , wherein the feedback is carried in a medium access control (MAC) control element (MAC-CE) or a protocol data unit (PDU) that has a header associated with calibrating the one or more first Tx/Rx imbalance values.
4 . The UE of claim 1 , wherein transmission of the feedback and the SRS to the assisting node enables the assisting node to obtain one or more third Tx/Rx imbalance values associated with the assisting node.
5 . The UE of claim 1 , wherein the assisting node is an assisting network node that communicates with the UE over an access link.
6 . The UE of claim 1 , wherein the processing system is further configured to cause the UE to:
transmit, to the assisting node, information that indicates a capability to calibrate the Tx/Rx mismatch associated with the UE.
7 . The UE of claim 6 , wherein the information transmitted to the assisting node indicates one or more Tx/Rx calibration procedures supported by the UE.
8 . The UE of claim 6 , wherein the information transmitted to the assisting node indicates a periodicity at which to perform one or more Tx/Rx calibration procedures.
9 . The UE of claim 6 , wherein the processing system is further configured to cause the UE to:
transmit, to the assisting node, Layer 1 or Layer 2 (L1/L2) signaling that includes a request to calibrate the Tx/Rx mismatch associated with the UE.
10 . The UE of claim 6 , wherein the processing system is further configured to cause the UE to:
receive, from the assisting node, radio resource control (RRC) signaling that includes configuration information to calibrate the Tx/Rx mismatch associated with the UE.
11 . The UE of claim 1 , wherein the feedback is included in a medium access control (MAC) control element (MAC-CE) or a protocol data unit (PDU) that has a header to indicate that a payload of the MAC-CE or the PDU carries the feedback indicating the first CSI-RS or the estimated effective downlink channel.
12 . The UE of claim 1 , wherein the processing system is further configured to cause the UE to:
estimate the downlink channel estimate based on the second CSI-RS.
13 . The UE of claim 12 , wherein the processing system is further configured to cause the UE to:
select the precoder based on the downlink channel estimate.
14 . The UE of claim 1 , wherein the assisting node is an assisting UE that communicates with the UE over a sidelink.
15 . A user equipment (UE) for wireless communication, comprising:
one or more antennas; and
a processing system that includes one or more processors and one or more memories that store code for the one or more processors, the processing system configured to cause the UE to:
receive, from an assisting node, assistance information that relates to a transmit/receive (Tx/Rx) mismatch associated with the UE;
obtain one or more Tx/Rx imbalance values associated with the UE in accordance with the assistance information received from the assisting node, wherein the assistance information is carried in a medium access control (MAC) control element (MAC-CE) or a protocol data unit (PDU) that has a header associated with calibrating the one or more Tx/Rx imbalance values;
estimate an effective uplink channel in accordance with a downlink channel estimate associated with a downlink reference signal and in accordance with the one or more Tx/Rx imbalance values associated with the UE; and
transmit an uplink communication using a precoder associated with the estimated effective uplink channel.
16 . A method for wireless communication by a user equipment (UE), comprising:
receiving, from an assisting node, a first channel state information reference signal (CSI-RS);
transmitting, to the assisting node, feedback that indicates the first CSI-RS or an estimate of an effective downlink channel associated with the first CSI-RS;
transmitting, to the assisting node, a sounding reference signal (SRS) including one or more first transmit/receive (Tx/Rx) imbalance values that relates to a Tx/Rx mismatch associated with the UE and is in accordance with the feedback;
receiving, from the assisting node, one or more second Tx/Rx imbalance values;
receiving, from the assisting node, a second CSI-RS;
estimating an effective uplink channel in accordance with a downlink channel estimate associated with the second CSI-RS and in accordance with the one or more second Tx/Rx imbalance values; and
transmitting an uplink communication using a precoder associated with the estimated effective uplink channel.
17 . The method of claim 16 , further comprising:
estimating one or more third Tx/Rx imbalance values associated with the assisting node in accordance with the first CSI-RS and information that relates to the Tx/Rx mismatch associated with the UE; and
transmitting, to the assisting node, feedback that indicates the estimated one or more third Tx/Rx imbalance values associated with the assisting node.
18 . The method of claim 16 , wherein the feedback is carried in a medium access control (MAC) control element (MAC-CE) or a protocol data unit (PDU) that has a header associated with calibrating the one or more first Tx/Rx imbalance values.
19 . The method of claim 16 , wherein transmitting the feedback and the SRS to the assisting node enables the assisting node to obtain one or more third Tx/Rx imbalance values associated with the assisting node.
20 . The method of claim 16 , wherein the assisting node is an assisting network node that communicates with the UE over an access link.
21 . The method of claim 16 , further comprising:
transmitting, to the assisting node, information that indicates a capability to calibrate the Tx/Rx mismatch associated with the UE.
22 . The method of claim 21 , wherein the information transmitted to the assisting node indicates one or more Tx/Rx calibration procedures supported by the UE.
23 . The method of claim 21 , wherein the information transmitted to the assisting node indicates a periodicity at which to perform one or more Tx/Rx calibration procedures.
24 . The method of claim 21 , further comprising:
transmitting, to the assisting node, Layer 1 or Layer 2 (L1/L2) signaling that includes a request to calibrate the Tx/Rx mismatch associated with the UE.
25 . The method of claim 21 , further comprising:
receiving, from the assisting node, radio resource control (RRC) signaling that includes configuration information to calibrate the Tx/Rx mismatch associated with the UE.
26 . The method of claim 16 , wherein the feedback is included in a medium access control (MAC) control element (MAC-CE) or a protocol data unit (PDU) that has a header to indicate that a payload of the MAC-CE or the PDU carries the feedback indicating the first CSI-RS or the estimated effective downlink channel.
27 . The method of claim 16 , further comprising:
estimating the downlink channel estimate based on the second CSI-RS.
28 . The method of claim 27 , further comprising:
selecting the precoder based on the downlink channel estimate.
29 . The method of claim 16 , wherein the assisting node is an assisting UE that communicates with the UE over a sidelink.
30 . A method for wireless communication by a user equipment (UE), comprising:
receiving, from an assisting node, assistance information that relates to a transmit/receive (Tx/Rx) mismatch associated with the UE;
obtaining one or more Tx/Rx imbalance values associated with the UE in accordance with the assistance information received from the assisting node, wherein the assistance information is carried in a medium access control (MAC) control element (MAC-CE) or a protocol data unit (PDU) that has a header associated with calibrating the one or more Tx/Rx imbalance values;
estimating an effective uplink channel in accordance with a downlink channel estimate associated with a downlink reference signal and in accordance with the one or more Tx/Rx imbalance values associated with the UE; and
transmitting an uplink communication using a precoder associated with the estimated effective uplink channel.