Automatic gain control (AGC) symbol indication
Aspects of the present disclosure provide techniques for techniques and apparatuses for mitigating self-interference (SI) at a wireless node engaging in full duplex (FD) communication. A method that may be performed by a network entity includes determining a trigger condition is satisfied for requesting an uplink (UL) signal from a user equipment (UE) for SI measurement, transmitting, to the UE, an indication to transmit the UL signal in one or more first symbols, wherein the one or more first symbols are prior to one or more second symbols for UL transmission by the UE, and wherein the one or more first symbols are scheduled for a downlink (DL) transmission by the network entity in a full duplex (FD) mode, measuring the UL signal, adjusting an automatic gain control (AGC) level based on the measurements, and using the adjusted AGC level to receive the UL transmission from the UE.
1. An apparatus for wireless communication, comprising:
a memory; and
one or more processors coupled to the memory, the memory and the one or more processors being configured to:
determine at least one of:
a local reflector has been removed, added, or changed;
a change in a beam pair used for communication between the apparatus and a user equipment (UE);
non-linearities of one or more filters in a transmit (TX) chain or a receive (RX) chain at the apparatus;
an instantaneous downlink signal transmitted by the apparatus;
a threshold amount of time has passed since a last measurement was performed by the apparatus for self-interference estimation for FD communications; or
a threshold amount of time has passed since transmitting a downlink transmission by the apparatus;
in response to the determining, transmit, to the UE, an indication to transmit an uplink signal in one or more first symbols, wherein the one or more first symbols are prior to one or more second symbols for uplink transmission by the LE, and wherein the one or more first symbols are scheduled for a downlink transmission by the apparatus in a full duplex (FD) mode;
perform a self-interference measurement of the uplink signal, from the UE, in the one or more first symbols;
adjust an automatic gain control (AGC) level at the apparatus based on the self-interference measurement; and
use the adjusted AGC level during the one or more second symbols to receive the uplink transmission from the UE.
2. The apparatus of claim 1 , wherein the memory and the one or more processors being configured to transmit the indication to the UE comprises the memory and the one or more processors being configured to transmit the indication to the UE in downlink control information (DCI) scheduling the uplink transmission.
3. The apparatus of claim 1 , wherein the memory and the one or more processors being configured to transmit the indication to the UE comprises the memory and the one or more processors being configured to transmit the indication to the UE in a medium access control (MAC) control element (CE) (MAC-CE) activating the uplink transmission.
4. The apparatus of claim 1 , wherein the uplink signal comprises a random sequence or a preconfigured sequence.
5. The apparatus of claim 1 , wherein the uplink signal comprises a repetition of a first symbol, of the one or more second symbols, of the uplink transmission.
6. The apparatus of claim 1 , wherein a number of the one or more first symbols used to transmit the uplink signal is based, at least in part, on a subcarrier spacing (SCS) of at least one of: the uplink transmission, the downlink transmission, or both.
7. The apparatus of claim 1 , wherein the one or more first symbols comprise one or more symbols immediately preceding the one or more second symbols.
8. The apparatus of claim 1 , wherein the memory and the one or more processors being configured to adjust the AGC level at the apparatus comprises the memory and the one or more processors being configured to adjust the AGC level to mitigate self-interference at the apparatus for full-duplex communications in the second one or more symbols.
9. The apparatus of claim 1 , wherein the memory and the one or more processors being configured to use the adjusted AGC level during the second one or more symbols comprises the memory and the one or more processors being configured to engage in full duplex communication including the memory and the one or more processor being configured to, simultaneously in the second one or more symbols:
apply the adjusted AGC level to receive, from the UE, the uplink transmission; and
transmit, to a second UE, the downlink transmission in the FD mode.
10. The apparatus of claim 1 , wherein the memory and the one or more processors being configured to use the adjusted AGC level during the second one or more symbols comprises the memory and the one or more processors being configured to engage in full duplex communication including the memory and the one or more processor being configured to, simultaneously in the second one or more symbols:
apply the adjusted AGC level to receive, from the UE, the uplink transmission; and
transmit, to the UE, the downlink transmission in the FD mode.
11. The apparatus of claim 1 , wherein the memory and the one or more processors being configured to perform the self-interference measurement of the uplink signal comprises the memory and the one or more processor being configured to:
perform a received signal strength indicator (RSSI) measurement of the uplink signal in the one or more first symbols in the FD mode; and
estimate a self-interference level based on the RSSI measurement.
12. The apparatus of claim 11 , wherein the memory and the one or more processors being configured to use the adjusted AGC level during the one or more second symbols to receive the uplink transmission from the UE comprises the memory and the one or more processors being configured to:
adjust a gain amount at an analog to digital converter (ADC) output of the uplink transmission at the apparatus, wherein the amount of gain is based on the RSSI measurement of the uplink signal.
13. A method for wireless communication by a network entity, comprising:
determining at least one of:
a local reflector has been removed, added, or changed;
a change in a beam pair used for communication between the network entity and a user equipment (UE);
non-linearities of one or more filters in a transmit (TX) chain or a receive (RX) chain at the network entity;
an instantaneous downlink signal transmitted by the network entity;
a threshold amount of time has passed since a last measurement was performed by the network entity for self-interference estimation for FD communications; or
a threshold amount of time has passed since transmitting a downlink transmission by the network entity;
in response to the determining, transmitting, to the UE, an indication to transmit an uplink signal in one or more first symbols, wherein the one or more first symbols are prior to one or more second symbols for uplink transmission by the UE, and wherein the one or more first symbols are scheduled for a downlink transmission by the network entity in a full duplex (FD) mode;
performing a self-interference measurement of the uplink signal, from the UE, in the one or more first symbols;
adjusting an automatic gain control (AGC) level at the network entity based on the self-interference measurements in the first one or more m; and
using the adjusted AGC level during the one or more second symbols to receive the uplink transmission from the UE.