Control signaling for special cell mobility
Methods, systems, and devices for wireless communications are described. In some systems, a network entity may configure a user equipment (UE) with a set of cells supporting Layer 1 (L1) mobility, Layer 2 (L2) mobility, or both for special cells (SpCells). The network entity may transmit a control signal, such as a medium access control (MAC) control element (CE) or a downlink control information (DCI) message, to the UE to update an SpCell. The control signal may include a cell identifier (ID) indicating which cell to set as the SpCell. Additionally, the control signal may include a transmission/reception point (TRP) ID indicating which TRP to set as the primary TRP (pTRP) for the SpCell. In response to the control signal, the UE may switch from a current SpCell to the cell indicated by the control signal and may communicate with the network via the pTRP of the new SpCell.
1 . An apparatus for wireless communications at a user equipment (UE), comprising:
at least one processor;
at least one memory coupled with the at least one processor; and
instructions stored in the at least one memory and executable by the at least one processor to cause the apparatus to:
receive a first control signal indicating a configuration of a plurality of cells supporting mobility for the UE, a first cell of the plurality of cells being a special cell for communication;
receive a second control signal indicating to update the special cell for communication from the first cell to a second cell of the plurality of cells, the second control signal comprising:
a first field that comprises a cell identifier indicating the second cell,
a second field that comprises an index indicating a primary transmission/reception point for activation for the second cell, and
a third field that comprises an identifier of a channel state information reference signal for tracking indicating one or more transmission configuration indicator states for activation for the second cell; and
communicate with the second cell via the primary transmission/reception point in accordance with a transmission configuration indicator state of the one or more transmission configuration indicator states based at least in part on the second control signal.
2 . The apparatus of claim 1 , wherein the second control signal further comprises a fourth field that comprises a configuration identifier indicating a configuration for the special cell, and the instructions are further executable by the at least one processor to cause the apparatus to:
activate the configuration for the special cell from a plurality of configurations available for the second cell based at least in part on the second control signal, wherein the communicating is further based at least in part on the activated configuration for the special cell.
3 . The apparatus of claim 1 , wherein the second cell is deactivated based at least in part on the first control signal and the second control signal comprises the third field that comprises the identifier of the channel state information reference signal for tracking based at least in part on the second cell being deactivated, and the instructions are further executable by the at least one processor to cause the apparatus to:
activate the second cell in response to receiving the second control signal; and
perform beam refinement for the second cell based at least in part on the identifier of the channel state information reference signal for tracking.
4 . The apparatus of claim 3 , wherein:
the identifier of the channel state information reference signal for tracking corresponds to a plurality of transmission/reception points for the second cell; and
the identifier of the channel state information reference signal for tracking indicates the one or more transmission configuration indicator states to activate for the second cell, one or more reference signals for beam refinement for the second cell, or both.
5 . The apparatus of claim 1 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
deactivate one or more cells based at least in part on the second control signal further indicating the one or more cells to deactivate.
6 . The apparatus of claim 5 , wherein the second control signal indicates one or more layer one measurement identifiers and reporting configurations corresponding to the one or more cells to deactivate, one or more transmission/reception points associated with the one or more cells to deactivate, or a combination thereof.
7 . The apparatus of claim 5 , wherein the instructions to deactivate the one or more cells are executable by the at least one processor to cause the apparatus to:
deactivate a plurality of transmission/reception points associated with the one or more cells.
8 . The apparatus of claim 1 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
activate one or more additional transmission/reception points associated with the second cell based at least in part on the second control signal indicating to update the special cell for communication with the second cell.
9 . The apparatus of claim 1 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
activate one or more transmission/reception points associated with the plurality of cells based at least in part on the second control signal comprising a bit map for transmission/reception point activation.
10 . The apparatus of claim 9 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
deactivate one or more other transmission/reception points associated with the plurality of cells based at least in part on the bit map for transmission/reception point activation.
11 . The apparatus of claim 1 , wherein:
the second control signal comprises a logical channel identifier indicating that the second control signal configures the UE to switch the special cell from the first cell to the second cell; or
the second control signal corresponds to a downlink control information format indicating that the second control signal configures the UE to switch the special cell from the first cell to the second cell.
12 . The apparatus of claim 1 , wherein the second control signal further comprises a set of reserved bits indicating which fields are present within the second control signal, indicating to deactivate the first cell configured as the special cell for communication, indicating to maintain the first cell configured as the special cell for communication as active, or a combination thereof.
13 . The apparatus of claim 1 , wherein:
the first control signal configures a first primary transmission/reception point for the second cell from a plurality of transmission/reception points associated with the second cell; and
the primary transmission/reception point for activation for the second cell indicated using the second control signal comprises a second primary transmission/reception point from the plurality of transmission/reception points different from the first primary transmission/reception point.
14 . The apparatus of claim 1 , wherein:
the first control signal comprises a radio resource control signal; and
the second control signal comprises a downlink control information signal.
15 . The apparatus of claim 1 , wherein:
the first control signal comprises a radio resource control signal; and
the second control signal comprises a medium access control control element.
16 . An apparatus for wireless communications, comprising:
at least one processor;
at least one memory coupled with the at least one processor, and instructions stored in the at least one memory and executable by the at least one processor to cause the apparatus to:
transmit a first control signal configuring a plurality of cells supporting mobility for a user equipment (UE), a first cell of the plurality of cells being a special cell for communication for the UE;
transmit a second control signal indicating for the UE to update the special cell for communication from the first cell to a second cell of the plurality of cells, the second control signal comprising:
a first field that comprises a cell identifier indicating the second cell,
a second field that comprises an index indicating a primary transmission/reception point for activation for the second cell, and
a third field that comprises an identifier of a channel state information reference signal for tracking indicating one or more transmission configuration indicator states for activation for the second cell; and
communicate via the primary transmission/reception point for the second cell in accordance with a transmission configuration indicator state of the one or more transmission configuration indicator states based at least in part on the second control signal.
17 . The apparatus of claim 16 , wherein the second control signal further comprises a fourth field that comprises a configuration identifier indicating a configuration for the special cell, and the instructions are further executable by the at least one processor to cause the apparatus to:
activate the configuration for the special cell from a plurality of configurations available for the second cell based at least in part on the second control signal, wherein the communicating is further based at least in part on the activated configuration for the special cell.
18 . The apparatus of claim 16 , wherein the instructions are further executable by the at least one processor to cause the apparatus to:
generate a bit map for transmission/reception point activation indicating one or more transmission/reception points associated with the plurality of cells for the UE to activate, wherein the second control signal further comprises the bit map.
19 . The apparatus of claim 18 , wherein the bit map further indicates one or more other transmission/reception points associated with the plurality of cells for the UE to deactivate.
20 . The apparatus of claim 16 , wherein:
the second cell is deactivated for the UE based at least in part on the first control signal; and
the second control signal comprises the third field that comprises the identifier of the channel state information reference signal for tracking based at least in part on the second cell being deactivated for the UE.
21 . The apparatus of claim 20 , wherein:
the identifier of the channel state information reference signal for tracking corresponds to a plurality of transmission/reception points for the second cell; and
the identifier of the channel state information reference signal for tracking indicates the one or more transmission configuration indicator states to activate for the second cell, one or more reference signals for beam refinement for the second cell, or both.
22 . The apparatus of claim 16 , wherein the second control signal further indicates one or more cells for the UE to deactivate.
23 . The apparatus of claim 22 , wherein the second control signal indicates one or more layer one measurement identifiers and reporting configurations corresponding to the one or more cells for the UE to deactivate, one or more transmission/reception points associated with the one or more cells for the UE to deactivate, or a combination thereof.
24 . The apparatus of claim 16 , wherein:
the second control signal comprises a logical channel identifier indicating that the second control signal configures the UE to switch the special cell from the first cell to the second cell; or
the second control signal corresponds to a downlink control information format indicating that the second control signal configures the UE to switch the special cell from the first cell to the second cell.
25 . The apparatus of claim 16 , wherein the second control signal further comprises a set of reserved bits indicating which fields are present within the second control signal, indicating for the UE to deactivate the first cell configured as the special cell for communication, indicating for the UE to maintain the first cell configured as the special cell for communication as active, or a combination thereof.
26 . The apparatus of claim 16 , wherein:
the first control signal comprises a radio resource control signal; and
the second control signal comprises a downlink control information signal.
27 . The apparatus of claim 16 , wherein:
the first control signal comprises a radio resource control signal; and
the second control signal comprises a medium access control control element.
28 . A method for wireless communications at a user equipment (UE), comprising:
receiving a first control signal indicating a configuration of a plurality of cells supporting mobility for the UE, a first cell of the plurality of cells being a special cell for communication;
receiving a second control signal indicating to update the special cell for communication from the first cell to a second cell of the plurality of cells, the second control signal comprising:
a first field that comprises a cell identifier indicating the second cell,
a second field that comprises an index indicating a primary transmission/reception point for activation for the second cell, and
a third field that comprises an identifier of a channel state information reference signal for tracking indicating one or more transmission configuration indicator states for activation for the second cell; and
communicating with the second cell via the primary transmission/reception point in accordance with a transmission configuration indicator state of the one or more transmission configuration indicator states based at least in part on the second control signal.
29 . The method of claim 28 , wherein the second control signal further comprises a fourth field that comprises a configuration identifier indicating a configuration for the special cell, the method further comprising:
activating the configuration for the special cell from a plurality of configurations available for the second cell based at least in part on the second control signal, wherein the communicating is further based at least in part on the activated configuration for the special cell.
30 . A method for wireless communications, comprising:
transmitting a first control signal configuring a plurality of cells supporting mobility for a user equipment (UE), a first cell of the plurality of cells being a special cell for communication for the UE;
transmitting a second control signal indicating for the UE to update the special cell for communication from the first cell to a second cell of the plurality of cells, the second control signal comprising:
a first field that comprises a cell identifier indicating the second cell,
a second field that comprises an index indicating a primary transmission/reception point for activation for the second cell, and
a third field that comprises an identifier of a channel state information reference signal for tracking indicating one or more transmission configuration indicator states for activation for the second cell; and
communicating via the primary transmission/reception point for the second cell in accordance with a transmission configuration indicator state of the one or more transmission configuration indicator states based at least in part on the second control signal.