Techniques for serving cell activation and deactivation using reference signals
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may be configured to receive, while the UE is in wireless communications with a first serving cell supported by a base station, an indication to activate or deactivate a second serving cell supported by the base station. The UE may receive a reference signal from the base station via the first serving cell, the reference signal received a duration of time after receipt of the indication, where the duration of time is an interruption period for the wireless communications with the first serving cell. The UE may then resume the wireless communications with the first serving cell based on the interruption period ending at receipt of the reference signal.
1 . An apparatus for wireless communication at a user equipment (UE), 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:
receive, from a network device via a medium access control element (MAC-CE) message and while the UE is in wireless communications with a first serving cell supported by the network device, an indication to activate or deactivate a second serving cell supported by the network device;
transmit a feedback message to the network device based at least in part on receipt of the indication to activate or deactivate the second serving cell;
receive a first reference signal from the network device via the second serving cell, the first reference signal received a first duration of time after receipt of the indication, wherein the first reference signal is a tracking reference signal, and wherein the first reference signal is triggered by the indication to activate or deactivate the second serving cell, and wherein a beginning of the first duration of time is based at least in part on transmission of the feedback message; and
activate the second serving cell.
2 . The apparatus of claim 1 , wherein the indication comprises an activation of the second serving cell supported by the network device, the instructions are further executable by the one or more processors to cause the apparatus to:
receive the first reference signal from the network device via the second serving cell based at least in part on receiving the indication to activate the second serving cell; and
establish wireless communications with the network device via the second serving cell based at least in part on receiving the first reference signal.
3 . The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive a prior reference signal from the network device via the first serving cell, the prior reference signal received a second duration of time after receipt of the indication and before reception of the first reference signal, wherein the first duration of time is an interruption period for the wireless communications with the first serving cell.
4 . The apparatus of claim 3 , wherein the prior reference signal received via the first serving cell and the first reference signal received via the second serving cell are received using a common set of time resources.
5 . The apparatus of claim 3 , wherein the prior reference signal received via the first serving cell and the first reference signal received via the second serving cell are received using a common sub-carrier spacing.
6 . The apparatus of claim 3 , wherein the prior reference signal received via the first serving cell and the first reference signal received via the second serving cell are received using different sub-carrier spacings.
7 . The apparatus of claim 3 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive, from the network device, control information that indicates that reference signals associated with both the first serving cell and the second serving cell have been activated, wherein receiving the prior reference signal via the first serving cell, receiving the first reference signal via the second serving cell, or both, is based at least in part on receiving the control information that the reference signals have been activated.
8 . The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receiving, from the network device via the first serving cell, a downlink control message scheduling a downlink transmission from the network device to the UE, wherein receiving the indication to activate or deactivate the second serving cell is based at least in part on the downlink control message.
9 . The apparatus of claim 8 , wherein the downlink control message further comprises an indication of a set of resource usable by the UE for receiving the first reference signal.
10 . The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
adjust an automatic gain control (AGC) associated with the second serving cell, a time or frequency tracking associated with the second serving cell, or both, based at least in part on the first reference signal.
11 . The apparatus of claim 10 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
establish a connection with the second serving cell, determining that the second serving cell has been activated, or both, based at least in part on the AGC, the time or frequency tracking, or both.
12 . The apparatus of claim 1 , wherein the first serving cell comprises a primary cell, and wherein the second serving cell comprises a secondary cell.
13 . The apparatus of claim 1 , wherein both the first serving cell and the second serving cell are each secondary cells.
14 . The apparatus of claim 1 , wherein the first serving cell and the second serving cell are in a same frequency band.
15 . The apparatus of claim 1 , wherein the first serving cell is associated with a first radio access technology, and the second serving cell is associated with a second radio access technology different from the first radio access technology.
16 . The apparatus of claim 1 , wherein the first serving cell is associated with a first frequency band of a first radio access technology, and the second serving cell is associated with a second frequency band of the first radio access technology.
17 . The apparatus of claim 1 , wherein the first serving cell is a primary-secondary cell of a secondary cell group, and wherein the second serving cell is a secondary cell of the secondary cell group.
18 . A method for wireless communication at a user equipment (UE), comprising:
receiving, from a network device via a medium access control element (MAC-CE) message and while the UE is in wireless communications with a first serving cell supported by the network device, an indication to activate or deactivate a second serving cell supported by the network device;
transmitting a feedback message to the network device based at least in part on receipt of the indication to activate or deactivate the second serving cell;
receiving a first reference signal from the network device via the second serving cell, the first reference signal received a first duration of time after receipt of the indication, wherein the first reference signal is a tracking reference signal, and wherein the first reference signal is triggered by the indication to activate or deactivate the second serving cell, and wherein a beginning of the first duration of time is based at least in part on transmission of the feedback message; and
activating the second serving cell.
19 . The method of claim 18 , wherein the indication comprises an activation of the second serving cell supported by the network device, the method further comprising:
receiving the first reference signal from the network device via the second serving cell based at least in part on receiving the indication to activate the second serving cell; and
establishing wireless communications with the network device via the second serving cell based at least in part on receiving the first reference signal.
20 . The method of claim 18 , further comprising:
receiving a prior reference signal from the network device via the first serving cell, the prior reference signal received a second duration of time after receipt of the indication and before reception of the first reference signal, wherein the first duration of time is an interruption period for the wireless communications with the first serving cell.
21 . The method of claim 20 , wherein the prior reference signal received via the first serving cell and the first reference signal received via the second serving cell are received using a common set of time resources.
22 . The method of claim 20 , wherein the prior reference signal received via the first serving cell and the first reference signal received via the second serving cell are received using a common sub-carrier spacing.
23 . The method of claim 20 , wherein the prior reference signal received via the first serving cell and the first reference signal received via the second serving cell are received using different sub-carrier spacings.
24 . The method of claim 20 , further comprising:
receiving, from the network device, control information that indicates that reference signals associated with both the first serving cell and the second serving cell have been activated, wherein receiving the prior reference signal via the first serving cell, receiving the first reference signal via the second serving cell, or both, is based at least in part on receiving the control information that the reference signals have been activated.
25 . The method of claim 18 , further comprising:
receiving, from the network device via the first serving cell, a downlink control message scheduling a downlink transmission from the network device to the UE, wherein receiving the indication to activate or deactivate the second serving cell is based at least in part on the downlink control message.
26 . The method of claim 25 , wherein the downlink control message further comprises an indication of a set of resource usable by the UE for receiving the first reference signal.
27 . An apparatus for wireless communication at a user equipment (UE), comprising:
means for receiving, from a network device via a medium access control element (MAC-CE) message and while the UE is in wireless communications with a first serving cell supported by the network device, an indication to activate or deactivate a second serving cell supported by the network device;
means for transmitting a feedback message to the network device based at least in part on receipt of the indication to activate or deactivate the second serving cell;
means for receiving a first reference signal from the network device via the second serving cell, the first reference signal received a first duration of time after receipt of the indication, wherein the first reference signal is a tracking reference signal, and wherein the first reference signal is triggered by the indication to activate or deactivate the second serving cell, and wherein a beginning of the first duration of time is based at least in part on transmission of the feedback message; and
means for activating the second serving cell.
28 . A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to:
receive, from a network device via a medium access control element (MAC-CE) message and while the UE is in wireless communications with a first serving cell supported by the network device, an indication to activate or deactivate a second serving cell supported by the network device;
transmit a feedback message to the network device based at least in part on receipt of the indication to activate or deactivate the second serving cell;
receive a first reference signal from the network device via the second serving cell, the first reference signal received a first duration of time after receipt of the indication, wherein the first reference signal is a tracking reference signal, and wherein the first reference signal is triggered by the indication to activate or deactivate the second serving cell, and wherein a beginning of the first duration of time is based at least in part on transmission of the feedback message; and
activate the second serving cell.