USER EQUIPMENT ASSISTED UPLINK SYNCHRONIZATION FOR INTER-CELL MOBILITY

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may monitor for reference signals from a first, reference cell and a second, deactivated cell, and the UE may report a timing difference between a first timing advance of the first cell and a second timing advance of the second cell. In some cases, the UE may report a timing difference periodically, and, in other cases, the UE may report a timing difference aperiodically. Once a network entity receives the timing difference, the network entity may determine the second timing difference for the UE to use to communicate with the second cell. The network entity may then signal the second timing difference to the UE when the second cell is activated for communications with the UE, and the UE may use the second timing advance to communicate with the second cell.

FIELD OF TECHNOLOGY

The following relates to wireless communications, including user equipment assisted uplink synchronization for inter-cell mobility.

BACKGROUND

A wireless multiple-access communications system may include one or more base stations, each supporting wireless communication for communication devices, which may be known as user equipment (UE). In some wireless communications systems, a network entity may configure a set of cells for communications with a UE. Improved techniques for supporting communications between a UE and one or more cells in a configured set of cells may be desirable.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support user equipment (UE) assisted uplink synchronization for inter-cell mobility. A UE may monitor for reference signals from a first, reference cell and a second, deactivated cell, and the UE may report a timing difference between a first timing advance of the first cell and a second timing advance of the second cell. In some cases, the UE may report a timing difference periodically, and, in other cases, the UE may report a timing difference aperiodically. Once a network entity receives the timing difference, the network entity may determine the second timing advance for the UE to use to communicate with the second cell. The network entity may then signal the second timing advance to the UE when the second cell is activated for communications with the UE, and the UE may use the second timing advance to communicate with the second cell.

A method for wireless communication at a user equipment (UE) is described. The method may include receiving an indication of a set of cells configured for communications with the UE, receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated, and transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

An apparatus for wireless communication at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive an indication of a set of cells configured for communications with the UE, receive a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated, and transmit an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

Another apparatus for wireless communication at a UE is described. The apparatus may include means for receiving an indication of a set of cells configured for communications with the UE, means for receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated, and means for transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor to receive an indication of a set of cells configured for communications with the UE, receive a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated, and transmit an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indication that the second cell may be activated, receiving an indication of the second timing advance for communicating with the second cell based on transmitting the timing difference, and communicating with the second cell using the second timing advance.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the indication of the timing difference may include operations, features, means, or instructions for transmitting a periodic transmission including the indication of the timing difference.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indication of a periodicity for transmitting periodic transmissions including indications of timing differences.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the indication of the timing difference may include operations, features, means, or instructions for transmitting an aperiodic transmission including the indication of the timing difference.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying one or more triggering conditions for transmitting the timing difference, where transmitting the aperiodic transmission may be based on at least one of the one or more triggering conditions being satisfied.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more triggering conditions include the timing difference satisfying a timing difference threshold, a change in the reference cell, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indication of the one or more triggering conditions for transmitting the timing difference.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a request to transmit the timing difference, where transmitting the aperiodic transmission may be based on receiving the request.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a set of multiple timing differences between timing advances for communicating with the first cell and timing advances for communicating with the second cell, the set of multiple timing differences including the timing difference between the first timing advance and the second timing advance.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indication that the first cell may be the reference cell, where the first cell may be selected as the reference cell based on cell quality, cell functionality, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indication of a set of multiple configurations for the UE to use to transmit the timing difference and receiving a control message indicating a configuration of the set of multiple configurations for the UE to use to transmit the timing difference, where transmitting the indication of the timing difference may be based on the configuration.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the timing difference between the first timing advance and the second timing advance may be based on a downlink propagation delay difference between a first downlink propagation delay associated with the first cell and a second downlink propagation delay associated with the second cell, a difference between a first downlink signal reception time associated with the first cell and a second downlink signal reception time associated with the second cell, or a combination thereof.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication of the timing difference may be transmitted in a medium access control control element or in a measurement report in uplink control information.

A method for wireless communication at a network entity is described. The method may include transmitting an indication of a set of cells configured for communications with a UE, transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell, and receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

An apparatus for wireless communication at a network entity is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit an indication of a set of cells configured for communications with a UE, transmit a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell, and receive an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

Another apparatus for wireless communication at a network entity is described. The apparatus may include means for transmitting an indication of a set of cells configured for communications with a UE, means for transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell, and means for receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

A non-transitory computer-readable medium storing code for wireless communication at a network entity is described. The code may include instructions executable by a processor to transmit an indication of a set of cells configured for communications with a UE, transmit a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell, and receive an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indication that the second cell may be activated and transmitting an indication of the second timing advance for communicating with the second cell based on receiving the timing difference.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the indication of the timing difference may include operations, features, means, or instructions for receiving a periodic transmission including the indication of the timing difference.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indication of a periodicity for periodic transmissions from the UE including indications of timing differences.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the indication of the timing difference may include operations, features, means, or instructions for receiving an aperiodic transmission including the indication of the timing difference.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indication of one or more triggering conditions for the UE to transmit the timing difference, where receiving the aperiodic transmission may be based on at least one of the one or more triggering conditions being satisfied.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more triggering conditions includes the timing difference satisfying a timing difference threshold, a change in the reference cell, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a request for the UE to transmit the timing difference, where receiving the aperiodic transmission may be based on transmitting the request.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a set of multiple timing differences between timing advances for communicating with the first cell and timing advances for communicating with the second cell, the set of multiple timing differences including the timing difference between the first timing advance and the second timing advance.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indication that the first cell may be the reference cell, where the first cell may be selected as the reference cell based on cell quality, cell functionality, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indication of a set of multiple configurations for the UE to use to transmit the timing difference and transmitting a control message indicating a configuration of the set of multiple configurations for the UE to use to transmit the timing difference, where receiving the indication of the timing difference may be based on the configuration.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the timing difference between the first timing advance and the second timing advance may be based on a downlink propagation delay difference between a first downlink propagation delay associated with the first cell and a second downlink propagation delay associated with the second cell, a difference between a first downlink signal reception time associated with the first cell and a second downlink signal reception time associated with the second cell, or a combination thereof.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication of the timing difference may be received in a medium access control control element or in a measurement report in uplink control information.

DETAILED DESCRIPTION

In some wireless communications systems, a network entity may configure a set of cells for communications with a user equipment (UE). The configured set of cells may include activated cells and deactivated cells. A UE may communicate with the activated cells in the configured set of cells, and the deactivated cells may be subsequently activated for communications with the UE. A network entity may use dynamic signaling (e.g., layer one (L1) or layer two (L2) signaling) to activate and deactivate cells in the configured set of cells to allow a UE to communicate with different subsets of the configured set of cells.

Once a cell is activated, a UE may perform a random access channel (RACH) procedure to synchronize timing with the cell, and the UE may communicate with the cell after uplink synchronization. For instance, the UE may identify a timing advance for communicating with the cell in the RACH procedure, and the UE may communicate with the cell using the timing advance. In some cases, however, by performing a RACH procedure, a UE may experience increased latency and power consumption when a cell is activated for communications with the UE. This latency and power consumption may negate the benefits of dynamic activation of cells, which may be detrimental to a wireless communications system.

As described herein, a wireless communications system may support efficient techniques for facilitating uplink synchronization at a UE with a cell once the cell is activated for communications with the UE. A UE may monitor for reference signals from a first, reference cell and a second, deactivated cell, and the UE may report a timing difference between a first timing advance of the first cell and a second timing advance of the second cell. In some cases, the UE may report a timing difference periodically, and, in other cases, the UE may report a timing difference aperiodically (e.g., in response to a request or based on one or more triggering conditions being satisfied). Once a network entity receives the timing difference, the network entity may determine the second timing advance for the UE to use to communicate with the second cell. The network entity may then signal the second timing advance to the UE when the second cell is activated for communications with the UE, and the UE may use the second timing advance to communicate with the second cell.

In the case of the techniques described herein applied in the context of a disaggregated RAN architecture, one or more components of the disaggregated RAN architecture may be configured to support cell management for inter-cell mobility as described herein. For example, some operations described as being performed by a UE115or a network entity105(e.g., a base station140) may additionally, or alternatively, be performed by one or more components of the disaggregated RAN architecture (e.g., IAB nodes104, DUs165, CUs160, RUs170, RIC175, SMO180).

The communication links125shown in the wireless communications system100may include downlink transmissions (e.g., forward link transmissions) from a network entity105to a UE115(e.g., in a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH)), uplink transmissions (e.g., return link transmissions) from a UE115to a network entity105(e.g., in a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH)), or both, among other configurations of transmissions. Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode).

In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that may provide access for different types of devices. A UE115may be configured with a primary cell (PCell) and one or more secondary cells (SCells) with which to communicate. For instance, the UE115may communicate with the PCell and the one or more SCells if the UE115is configured for dual connectivity (DC) or carrier aggregation (CA). The UE115may use the PCell for initial access to a network (e.g., initial access to a master cell group (MCG)) and other communications, and the UE115may use the one or more SCells for supplementary communications. In some cases, the UE115may be configured with a primary secondary cell (PSCell) that the UE115may use for initial access to one or more SCells (e.g., initial access to a secondary cell group (SCG)). A PCell or a PSCell (primary cell of an SCG) may be referred to as a special cell (SpCell). An SpCell configuration for an MCG may correspond to a PCell configuration, and an SpCell configuration for an SCG may correspond to a PSCell configuration.

In wireless communications system100, a network entity105may configure a set of cells for communications with a UE115. The network entity105may be connected to or support communications via at least one cell of the set of cells, and the network entity105may configure the UE115with the set of cells via the at least one cell. The configured set of cells may include activated cells and deactivated cells. A UE115may communicate with the activated cells in the configured set of cells, and the deactivated cells may be subsequently activated for communications with the UE115(e.g., when appropriate). A network entity105may use dynamic signaling (e.g., L1 or L2 signaling, such as downlink control information (DCI) messages or MAC control elements (MAC-CEs)) to activate and deactivate cells in the configured set of cells to maximize throughput (e.g., by allowing a UE115to communicate with an optimal subset of the configured set of cells). The use of dynamic signaling to activate and deactivate cells in a configured set of cells may be referred to as L1/L2-based inter-cell mobility.

The wireless communications system100may support techniques for L1/L2-based inter-cell mobility. For instance, the wireless communications system100may support the configuration and maintenance of multiple candidate cells in a configured set of cells to allow fast application of configurations for the candidate cells. Further, the wireless communications system100may support a dynamic switching mechanism among candidate serving cells (e.g., including an SpCell and an SCell) for potential applicable scenarios based on L1/L2 signaling. The wireless communications system100may also support L1 enhancements for inter-cell beam management, including L1 measurements and reporting and beam indication. The wireless communications system100may also support timing advance management and CU-DU interface signaling to support L1/L2 mobility (e.g., if appropriate). In some examples, frequency range two (FR2) specific enhancements may not be precluded (e.g., if any).

In addition, the described techniques may provide for the design and enhancement of L1/L2-based inter-cell mobility. A procedure for L1/L2-based inter-cell mobility may be applicable in multiple scenarios. In one example, L1/L2-based inter-cell mobility may be used for standalone, CA, or NR-DC cases supporting a serving cell change within a configured grant. In another example, L1/L2-based inter-cell mobility may be used for an intra-DU case or an intra-CU and inter-DU case (e.g., applicable for standalone and CA, where no new RAN interfaces may be expected). In yet another example, L1/L2-based inter-cell mobility may be used for both intra-frequency and inter-frequency communications. In yet another example, L1/L2-based inter-cell mobility may be used for communications in both a frequency range one (FR1) and a frequency range two (FR2). In yet another example, L1/L2-based inter-cell mobility may be used for communications with source and target cells that may be synchronized or non-synchronized.

FIG.2illustrates an example of inter-cell mobility200in accordance with one or more aspects of the present disclosure. A UE115-amay be configured with a set of cells (e.g., configured cell set205) for inter-cell mobility (e.g., L1/L2 mobility). A network entity105may use RRC signaling to configure the set of cells. In some examples, there may be one or more cells210outside of the configured cell set205. Cells in the configured cell set205may be further characterized into activated cells215and deactivated cells220(e.g., including an SpCell and SCells). An activated cell set may correspond to a group of cells that can be readily used for data and control information transfer. For example, for cells in the activated cell set, control channels may be monitored, synchronization may be maintained, or a timing advance may be maintained. A deactivated cell set may correspond to a group of cells that are not activated but can be quickly activated by L1/L2 signaling. For example, for deactivated cells, a control channel may not be monitored, synchronization may not be maintained, or a timing advance may not be maintained. The UE115-amay perform measurements (e.g., periodically according to a configuration) on the cells in the configured cell set205for fast L1/L2 mobility handover. Cells in the configured cell set205may belong to (e.g., be supported or used for communications by) a same network entity105(e.g., DU) or different network entities105(e.g., DUs). The configured cell set205may be large enough to cover reasonable mobility areas, and mobility within the configured cell set may be done through L1/L2 signaling.

In an inter-cell mobility scenario, cells in the configured cell set205may not be collocated, and the UE115-amay experience different propagation delays to different cells. As such, different timing information may be used or necessary based on a timing advance group (TAG) allocation of a cell. A TAG may refer to a group of cells with which a UE115may communicate using the same timing information (e.g., a same timing advance). The configured cell set205may include cells in multiple TAGs225, including a first TAG225-a, a second TAG225-b, and a third TAG225-c.

The UE115-amay obtain initial timing advance information for a cell via a RACH procedure. For an SpCell, the UE115-amay initiate a RACH procedure to obtain timing advance information. For an SCell, the UE115-amay perform a PDCCH ordered RACH procedure to obtain timing advance information. After an initial timing advance information acquisition, one or more cells may be deactivated in the configured cell set205. In some cases, however, the UE115-amay not be configured to perform measurements for deactivated cells220. Thus, at the time of cell activation, the UE115-amay perform a RACH procedure again to obtain timing advance information, and, by performing the RACH procedure, the UE115-amay experience increased latency and power consumption. This latency and power consumption may negate the benefits of dynamic activation of cells, which may be detrimental to a wireless communications system.

The wireless communications system100may support efficient techniques for facilitating uplink synchronization at the UE115-awith a cell once the cell is activated for communications with the UE115-a. For instance, the described techniques may allow for maintaining timing advance information for deactivated cells in the configured cell set205such that the timing advance information may be directly signaled to the UE115-aat the time of cell activation. As such, the UE115-amay avoid a RACH procedure at the time of cell activation, resulting in reduced latency and power consumption. Further, the described techniques may allow for fast L1 or L2 signaling to facilitate seamless UE mobility within the configured cell set205.

FIG.3illustrates an example of a wireless communications system300that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The wireless communications system300includes a UE115-b, which may be an example of a UE115described with reference toFIGS.1and2. The wireless communications system300also includes a cell105-a, a cell105-b, and a cell105-c, which may be an example of a network entity105or a cell described with reference toFIGS.1and2. The wireless communications system300may implement aspects of the wireless communications system100. For instance, the wireless communications system300may support efficient techniques for facilitating uplink synchronization at the UE115-bwith a cell once the cell is activated for communications with the UE115-b.

The first cell105-amay be activated for communications with the UE115-band may be a reference cell for timing advance maintenance (e.g., based on UE assistance). The reference cell may be a SpCell or a synchronized SCell. The second cell105-band the third cell105-cmay be SCells and may be deactivated for communications with the UE115-b. The timing advance information of the second cell105-band the third cell105-c(e.g., deactivated SCells) may be estimated based on downlink reference signal measurements. The first cell105-a, the second cell105-b, and the third cell105-cmay transmit reference signals305which may be received by the UE115-b. The reference signals305may be synchronization signal blocks (SSBs) or channel state information (CSI) reference signals (CSI-RSs). In some cases, the reference signals305may include existing reference signals used for L1 measurements for an L1 or L2 mobility cell set. Because the second cell105-band the third cell105-cmay be in a same TAG, the UE115-bmay monitor for the reference signals305from the second cell105-band avoid monitoring for the reference signals305from the third cell105-c. For instance, only one cell per TAG may be monitored for timing advance information.

The UE115-bmay estimate a first timing advance for communicating with the first cell105-a, and the UE115-bmay estimate a second timing advance for communicating with the second cell105-b. The UE115-bmay determine a timing difference310between the first timing advance and the second timing advance. In some examples, the UE115-bmay estimate a received reference signal timing difference between the reference signals305received from the second cell105-band the reference signals305received from the first cell105-a(e.g., with respect to the reference cell), and the UE115-bmay determine the timing difference310based on the received reference signal timing difference. In some examples, the UE115-bmay estimate a downlink propagation delay difference between a first downlink propagation delay for receiving the reference signals305from the first cell105-aand a second propagation delay for receiving the reference signals305from the second cell105-b, and the UE115-bmay determine the timing difference310based on the downlink propagation delay difference.

Once the UE115-bdetermines the timing difference310, the UE115-bmay report the timing difference310to a network entity105(e.g., via the first cell105-a). The timing difference310may be based on a downlink timing difference or a downlink propagation delay difference. The network entity105may then use the timing difference, or downlink propagation delay difference, to determine a timing advance for the UE115-bto use to communicate with the second cell105-b(e.g., once the second cell105-bis activated).

The UE115-bmay report to the network entity105regarding the timing difference310, and the report may include a current timing difference (e.g., the timing difference310) and a timing difference history including past timing differences (e.g., timing differences in the past x ms if the report is not sent periodically). In some examples, the UE115-bmay transmit the timing difference310in a dedicated MAC-CE or in joint signaling with an L1 measurement report. If the UE115-btransmits the timing difference310in the joint signaling, the measurement objects (e.g., the reference signals305) may be SSBs or CSI-RSs, and the UE115-bmay be configured to indicate the timing difference in the measurement report. For instance, the measurement report may include a field to indicate the timing difference310(e.g., a downlink propagation delay or downlink propagation delay difference).

In some aspects, the UE115-bmay transmit timing differences periodically (e.g., with a configured signaling periodicity) or aperiodically. In one example, the UE115-bmay transmit the timing differences periodically or aperiodically in dedicated or separate signaling (e.g., a dedicated MAC-CE) or in joint signaling with an L1 measurement report. In this example, a network entity105may indicate a periodicity with which the UE115-bmay transmit the timing differences (e.g., periodic with network configured periodicity f). Additionally, or alternatively, a network entity105may indicate triggering conditions for transmitting the timing differences aperiodically. The triggering conditions may include a timing difference satisfying a threshold or a change in a reference cell. If the UE115-bis configured to transmit the timing differences in joint signaling with an L1 measurement report, one or more of the triggering conditions may be included in a measurement report configuration for the L1 measurement report. Further, in some cases, a triggering condition (e.g., triggering event) may be added to a measurement report triggering list. In another example, the UE115-bmay transmit a timing difference in response to a request from a network entity105.

In an example of a triggering event configuration, a triggering event (e.g., event A7) may be defined for a timing difference between the first cell105-a(e.g., a reference cell) and the second cell105-bsatisfying a threshold. The UE115-bmay consider an entering condition for this triggering event to be satisfied when a first condition (e.g., condition A7-1) is satisfied. The first condition (e.g., inequality A7-1 or the entering condition) may be: Abs(Ms−Ref)>threshold, where Ms is a measurement result (e.g., first timing advance) of the second cell105-b(e.g., a serving cell) and Ref is a measurement result (e.g., second timing advance) of the first cell105-a(e.g., a reference cell). The UE115-bmay consider a leaving condition for this triggering event to be satisfied when a second condition (e.g., condition A7-2) is satisfied. The second condition (e.g., inequality A7-1 or the leaving condition) may be: Abs(Ms−Ref)>threshold, where Ms is a measurement result (e.g., first timing advance) of the second cell105-b(e.g., a serving cell) and Ref is a measurement result (e.g., second timing advance) of the first cell105-a(e.g., a reference cell). The UE115-bmay also, for a measurement of a timing difference, consider the second cell105-b(e.g., the serving cell) indicated by a measurement object associated with the triggering event.

In some aspects, the UE115-bmay receive, from a network entity105, an indication of one or more configurations (e.g., in an RRC configuration message) for transmitting timing differences to the network entity105(e.g., via the first cell105-a). A configuration for transmitting timing differences may indicate a reference cell for calculating timing differences (e.g., an SpCell or other synchronized SCells). In some cases, a network entity105may configure multiple reference cells. Additionally, or alternatively, a configuration for transmitting timing differences may include a timing difference reporting periodicity f, a timing difference aperiodic reporting triggering condition, or an indication of timing difference report content and related parameters (e.g., a timing difference reporting time window (x ms) for reporting past timing differences in aperiodic reporting). If the UE115-breceives an indication of multiple configurations for transmitting timing differences to the network entity105, the UE115-bmay receive an indication of a configuration of the multiple configurations to use for transmitting a timing difference or multiple timing differences (e.g., a network entity105may use DCI or a MAC-CE to switch configurations).

FIG.4illustrates an example of a process flow400that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The process flow400includes a UE115-c, which may be an example of a UE115described with reference toFIGS.1-3. The process flow400also includes a cell105-dand a cell105-e, which may be examples of network entities105or cells described with reference toFIGS.1-3. The process flow400may implement aspects of the wireless communications system100or the wireless communications system300. For instance, the process flow400may support efficient techniques for facilitating uplink synchronization at the UE115-cwith a cell once the cell is activated for communications with the UE115-c.

In the following description of the process flow400, the signaling exchanged between the UE115-c, the cell105-d, and the cell105-emay be exchanged in a different order than the example order shown, or the operations performed by the UE115-c, the cell105-d, and the cell105-emay be performed in different orders or at different times. Some operations may also be omitted from the process flow400, and other operations may be added to the process flow400.

At405, a network entity105may transmit a higher layer control message (e.g., an RRC configuration message) to a UE115-cvia a first cell105-d, and the UE115-cmay receive the higher layer control message. The higher layer control message may include a configuration of a set of cells with which the UE115-cmay communicate, and the set of cells may include the first cell105-dand a second cell105-e. The first cell105-dmay be activated, and the second cell105-emay be deactivated. In some examples, after receiving the higher layer control message (e.g., the RRC configuration message), the UE115-cmay transmit an acknowledgment to the network entity105(e.g., an RRC configuration or reconfiguration complete message).

At410, the UE115-cmay receive a first reference signal from the first cell105-d, and, at415, the UE115-cmay receive a second reference signal from the second cell105-e. At420, the UE115-cmay transmit an indication of a timing difference between a first timing advance for communicating with the first cell105-dand a second timing advance for communicating with the second cell105-e(e.g., a timing difference with respect to a reference cell). The UE115-cmay transmit the indication of the timing difference in a MAC-CE or in a measurement report in uplink control information.

The UE115-cmay determine that the first cell105-dis a reference cell, and the UE115-cmay transmit the indication of the timing difference between the first timing advance and the second timing advance based on determining that the first cell105-dis the reference cell. In some examples, the UE115-cmay receive an indication from a network entity105(e.g., via the first cell105-d) that the first cell105-dis the reference cell. The network entity105may select the first cell as the reference cell based on a cell quality of the first cell105-d(e.g., a reference signal received power (RSRP), a pathloss, or a signal-to-interference-plus-noise ratio (SINR) associated with communications between the first cell105-dand the UE115-c) or a cell functionality of the first cell105-d(e.g., always selecting an SpCell as the reference cell).

In some examples, the UE115-cmay transmit the indication of the timing difference in a periodic transmission. The UE115-cmay receive an indication of a periodicity for transmitting periodic transmissions with indications of timing differences. In other examples, the UE115-cmay transmit the indication of the timing difference in an aperiodic transmission (e.g., a single, standalone transmission). The UE115-cmay identify one or more triggering conditions for transmitting the timing difference, and the UE115-cmay transmit the aperiodic transmission with the timing difference if at least one of the triggering conditions is satisfied. The triggering conditions may include the timing difference satisfying a timing difference threshold or a change in a reference cell. The UE115-cmay receive an indication of the triggering conditions for transmitting the timing difference. In some examples, the UE115-cmay receive a request to transmit the timing difference, and the UE115-cmay transmit the aperiodic transmission with the timing difference in response to receiving the request.

In some examples, the UE115-cmay transmit multiple timing differences (e.g., for aperiodic reporting of timing advances) between timing advances for communicating with the first cell105-dand timing advances for communicating with the second cell105-e. The multiple timing differences may include the timing difference between the first timing advance for communicating with the first cell105-dand the second timing advance for communicating with the second cell105-e. The multiple timing differences may also include past timing differences between timing advances for communicating with the first cell105-dand timing advances for communicating with the second cell105-e(e.g., a history record of downlink timing differences with respect to the reference cell). The past timing differences may include the timing differences determined within a threshold amount of time (e.g., x ms), or the past timing differences may include a threshold quantity of past timing differences.

In some examples, the UE115-cmay receive an indication of multiple configurations to use to transmit the timing difference. The UE115-cmay then receive (e.g., in a lower layer control message) an indication of a configuration of the multiple configurations for the UE115-cto use to transmit the timing difference, and the UE115-cmay transmit the timing difference using the configuration. The timing difference between the first timing advance and the second timing advance may be based on a downlink propagation delay difference between a first propagation delay associated with the first cell105-dand a second downlink propagation delay associated with the second cell105-e. Additionally, or alternatively, the timing difference between the first timing advance and the second timing advance may be based on a difference between a first downlink signal reception time associated with the first cell105-d(e.g., a reception time of the reference signal at410) and a second downlink signal reception time associated with the second cell105-e(e.g., a reception time of the reference signal at415).

At425, the UE115-cmay receive a lower layer control message (e.g., used for L1/L2 mobility) from the first cell105-dindicating that the second cell105-eis activated. The lower layer control message may also indicate the second timing advance for communicating with the second cell105-e. A network entity105may determine the second timing advance based on the timing difference between the first timing advance and the second timing advance received from the UE115-c. At430, the UE115-cmay communicate (e.g., exchange control information and data) with the second cell105-eusing the second timing advance.

FIG.5shows a block diagram500of a device505that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The device505may be an example of aspects of a UE115as described herein. The device505may include a receiver510, a transmitter515, and a communications manager520. The device505may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The communications manager520, the receiver510, the transmitter515, or various combinations thereof or various components thereof may be examples of means for performing various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein. For example, the communications manager520, the receiver510, the transmitter515, or various combinations or components thereof may support a method for performing one or more of the functions described herein.

In some examples, the communications manager520may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver510, the transmitter515, or both. For example, the communications manager520may receive information from the receiver510, send information to the transmitter515, or be integrated in combination with the receiver510, the transmitter515, or both to obtain information, output information, or perform various other operations as described herein.

The communications manager520may support wireless communication at a UE in accordance with examples as disclosed herein. For example, the communications manager520may be configured as or otherwise support a means for receiving an indication of a set of cells configured for communications with the UE. The communications manager520may be configured as or otherwise support a means for receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated. The communications manager520may be configured as or otherwise support a means for transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

By including or configuring the communications manager520in accordance with examples as described herein, the device505(e.g., a processor controlling or otherwise coupled with the receiver510, the transmitter515, the communications manager520, or a combination thereof) may support techniques for reduced processing, reduced power consumption, and more efficient utilization of communication resources. Because the device505may continue to monitor for and perform measurements on reference signals from a cell that is deactivated and report timing differences between the timing advances for communicating with the cell and timing differences for communicating with a reference cell, a network entity105may maintain a timing advance for the device505to use to communicate with the cell. Thus, when the cell is activated, the network entity105may signal the timing advance for the device505to use to communicate with the cell, and the device505may avoid performing a RACH procedure to identify the timing advance (e.g., resulting in the reduced processing, reduced power consumption, and more efficient utilization of communication resources).

FIG.6shows a block diagram600of a device605that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The device605may be an example of aspects of a device505or a UE115as described herein. The device605may include a receiver610, a transmitter615, and a communications manager620. The device605may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The device605, or various components thereof, may be an example of means for performing various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein. For example, the communications manager620may include a cell configuration manager625, a reference signal manager630, a timing advance manager635, or any combination thereof. The communications manager620may be an example of aspects of a communications manager520as described herein. In some examples, the communications manager620, or various components thereof, may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver610, the transmitter615, or both. For example, the communications manager620may receive information from the receiver610, send information to the transmitter615, or be integrated in combination with the receiver610, the transmitter615, or both to obtain information, output information, or perform various other operations as described herein.

The communications manager620may support wireless communication at a UE in accordance with examples as disclosed herein. The cell configuration manager625may be configured as or otherwise support a means for receiving an indication of a set of cells configured for communications with the UE. The reference signal manager630may be configured as or otherwise support a means for receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated. The timing advance manager635may be configured as or otherwise support a means for transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

FIG.7shows a block diagram700of a communications manager720that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The communications manager720may be an example of aspects of a communications manager520, a communications manager620, or both, as described herein. The communications manager720, or various components thereof, may be an example of means for performing various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein. For example, the communications manager720may include a cell configuration manager725, a reference signal manager730, a timing advance manager735, a cell mobility manager740, a reference cell manager745, or any combination thereof. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses).

The communications manager720may support wireless communication at a UE in accordance with examples as disclosed herein. The cell configuration manager725may be configured as or otherwise support a means for receiving an indication of a set of cells configured for communications with the UE. The reference signal manager730may be configured as or otherwise support a means for receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated. The timing advance manager735may be configured as or otherwise support a means for transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

In some examples, the cell mobility manager740may be configured as or otherwise support a means for receiving an indication that the second cell is activated. In some examples, the timing advance manager735may be configured as or otherwise support a means for receiving an indication of the second timing advance for communicating with the second cell based on transmitting the timing difference. In some examples, the timing advance manager735may be configured as or otherwise support a means for communicating with the second cell using the second timing advance.

In some examples, to support transmitting the indication of the timing difference, the timing advance manager735may be configured as or otherwise support a means for transmitting a periodic transmission including the indication of the timing difference.

In some examples, the timing advance manager735may be configured as or otherwise support a means for receiving an indication of a periodicity for transmitting periodic transmissions including indications of timing differences.

In some examples, to support transmitting the indication of the timing difference, the timing advance manager735may be configured as or otherwise support a means for transmitting an aperiodic transmission including the indication of the timing difference.

In some examples, the timing advance manager735may be configured as or otherwise support a means for identifying one or more triggering conditions for transmitting the timing difference, where transmitting the aperiodic transmission is based on at least one of the one or more triggering conditions being satisfied.

In some examples, the one or more triggering conditions include the timing difference satisfying a timing difference threshold, a change in the reference cell, or a combination thereof.

In some examples, the timing advance manager735may be configured as or otherwise support a means for receiving an indication of the one or more triggering conditions for transmitting the timing difference.

In some examples, the timing advance manager735may be configured as or otherwise support a means for receiving a request to transmit the timing difference, where transmitting the aperiodic transmission is based on receiving the request.

In some examples, the timing advance manager735may be configured as or otherwise support a means for transmitting a set of multiple timing differences between timing advances for communicating with the first cell and timing advances for communicating with the second cell, the set of multiple timing differences including the timing difference between the first timing advance and the second timing advance.

In some examples, the reference cell manager745may be configured as or otherwise support a means for receiving an indication that the first cell is the reference cell, where the first cell is selected as the reference cell based on cell quality, cell functionality, or a combination thereof.

In some examples, the timing advance manager735may be configured as or otherwise support a means for receiving an indication of a set of multiple configurations for the UE to use to transmit the timing difference. In some examples, the timing advance manager735may be configured as or otherwise support a means for receiving a control message indicating a configuration of the set of multiple configurations for the UE to use to transmit the timing difference, where transmitting the indication of the timing difference is based on the configuration.

In some examples, the timing difference between the first timing advance and the second timing advance is based on a downlink propagation delay difference between a first downlink propagation delay associated with the first cell and a second downlink propagation delay associated with the second cell, a difference between a first downlink signal reception time associated with the first cell and a second downlink signal reception time associated with the second cell, or a combination thereof.

In some examples, the indication of the timing difference is transmitted in a medium access control control element or in a measurement report in uplink control information.

The communications manager820may support wireless communication at a UE in accordance with examples as disclosed herein. For example, the communications manager820may be configured as or otherwise support a means for receiving an indication of a set of cells configured for communications with the UE. The communications manager820may be configured as or otherwise support a means for receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated. The communications manager820may be configured as or otherwise support a means for transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

By including or configuring the communications manager820in accordance with examples as described herein, the device805may support techniques for reduced processing, reduced power consumption, and more efficient utilization of communication resources. Because the device805may continue to monitor for and perform measurements on reference signals from a cell that is deactivated and report timing differences between the timing advances for communicating with the cell and timing differences for communicating with a reference cell, a network entity105may maintain a timing advance for the device805to use to communicate with the cell. Thus, when the cell is activated, the network entity105may signal the timing advance for the device805to use to communicate with the cell, and the device805may avoid performing a RACH procedure to identify the timing advance (e.g., resulting in the reduced processing, reduced power consumption, and more efficient utilization of communication resources).

FIG.9shows a block diagram900of a device905that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The device905may be an example of aspects of a network entity105as described herein. The device905may include a receiver910, a transmitter915, and a communications manager920. The device905may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The communications manager920, the receiver910, the transmitter915, or various combinations thereof or various components thereof may be examples of means for performing various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein. For example, the communications manager920, the receiver910, the transmitter915, or various combinations or components thereof may support a method for performing one or more of the functions described herein.

In some examples, the communications manager920may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver910, the transmitter915, or both. For example, the communications manager920may receive information from the receiver910, send information to the transmitter915, or be integrated in combination with the receiver910, the transmitter915, or both to obtain information, output information, or perform various other operations as described herein.

The communications manager920may support wireless communication at a network entity in accordance with examples as disclosed herein. For example, the communications manager920may be configured as or otherwise support a means for transmitting an indication of a set of cells configured for communications with a UE. The communications manager920may be configured as or otherwise support a means for transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell. The communications manager920may be configured as or otherwise support a means for receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

By including or configuring the communications manager920in accordance with examples as described herein, the device905(e.g., a processor controlling or otherwise coupled with the receiver910, the transmitter915, the communications manager920, or a combination thereof) may support techniques for reduced processing, reduced power consumption, and more efficient utilization of communication resources. Because the device905may receive timing differences between the timing advances at a UE115for communicating with a cell that is deactivated and timing differences at the UE115for communicating with a reference cell, the device905may maintain a timing advance for the UE115to use to communicate with the cell. Thus, when the cell is activated, the device905may signal the timing advance for the UE115to use to communicate with the cell, and the UE115may avoid performing a RACH procedure with the device905to identify the timing advance (e.g., resulting in the reduced processing, reduced power consumption, and more efficient utilization of communication resources).

The device1005, or various components thereof, may be an example of means for performing various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein. For example, the communications manager1020may include a cell configuration manager1025, a reference signal manager1030, a timing advance manager1035, or any combination thereof. The communications manager1020may be an example of aspects of a communications manager920as described herein. In some examples, the communications manager1020, or various components thereof, may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver1010, the transmitter1015, or both. For example, the communications manager1020may receive information from the receiver1010, send information to the transmitter1015, or be integrated in combination with the receiver1010, the transmitter1015, or both to obtain information, output information, or perform various other operations as described herein.

The communications manager1020may support wireless communication at a network entity in accordance with examples as disclosed herein. The cell configuration manager1025may be configured as or otherwise support a means for transmitting an indication of a set of cells configured for communications with a UE. The reference signal manager1030may be configured as or otherwise support a means for transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell. The timing advance manager1035may be configured as or otherwise support a means for receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

FIG.11shows a block diagram1100of a communications manager1120that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The communications manager1120may be an example of aspects of a communications manager920, a communications manager1020, or both, as described herein. The communications manager1120, or various components thereof, may be an example of means for performing various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein. For example, the communications manager1120may include a cell configuration manager1125, a reference signal manager1130, a timing advance manager1135, a cell mobility manager1140, a reference cell manager1145, or any combination thereof. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses) which may include communications within a protocol layer of a protocol stack, communications associated with a logical channel of a protocol stack (e.g., between protocol layers of a protocol stack, within a device, component, or virtualized component associated with a network entity105, between devices, components, or virtualized components associated with a network entity105), or any combination thereof.

The communications manager1120may support wireless communication at a network entity in accordance with examples as disclosed herein. The cell configuration manager1125may be configured as or otherwise support a means for transmitting an indication of a set of cells configured for communications with a UE. The reference signal manager1130may be configured as or otherwise support a means for transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell. The timing advance manager1135may be configured as or otherwise support a means for receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

In some examples, the cell mobility manager1140may be configured as or otherwise support a means for transmitting an indication that the second cell is activated. In some examples, the timing advance manager1135may be configured as or otherwise support a means for transmitting an indication of the second timing advance for communicating with the second cell based on receiving the timing difference.

In some examples, to support receiving the indication of the timing difference, the timing advance manager1135may be configured as or otherwise support a means for receiving a periodic transmission including the indication of the timing difference.

In some examples, the timing advance manager1135may be configured as or otherwise support a means for transmitting an indication of a periodicity for periodic transmissions from the UE including indications of timing differences.

In some examples, to support receiving the indication of the timing difference, the timing advance manager1135may be configured as or otherwise support a means for receiving an aperiodic transmission including the indication of the timing difference.

In some examples, the timing advance manager1135may be configured as or otherwise support a means for transmitting an indication of one or more triggering conditions for the UE to transmit the timing difference, where receiving the aperiodic transmission is based on at least one of the one or more triggering conditions being satisfied.

In some examples, the one or more triggering conditions includes the timing difference satisfying a timing difference threshold, a change in the reference cell, or a combination thereof.

In some examples, the timing advance manager1135may be configured as or otherwise support a means for transmitting a request for the UE to transmit the timing difference, where receiving the aperiodic transmission is based on transmitting the request.

In some examples, the timing advance manager1135may be configured as or otherwise support a means for receiving a set of multiple timing differences between timing advances for communicating with the first cell and timing advances for communicating with the second cell, the set of multiple timing differences including the timing difference between the first timing advance and the second timing advance.

In some examples, the reference cell manager1145may be configured as or otherwise support a means for transmitting an indication that the first cell is the reference cell, where the first cell is selected as the reference cell based on cell quality, cell functionality, or a combination thereof.

In some examples, the timing advance manager1135may be configured as or otherwise support a means for transmitting an indication of a set of multiple configurations for the UE to use to transmit the timing difference. In some examples, the timing advance manager1135may be configured as or otherwise support a means for transmitting a control message indicating a configuration of the set of multiple configurations for the UE to use to transmit the timing difference, where receiving the indication of the timing difference is based on the configuration.

In some examples, the timing difference between the first timing advance and the second timing advance is based on a downlink propagation delay difference between a first downlink propagation delay associated with the first cell and a second downlink propagation delay associated with the second cell, a difference between a first downlink signal reception time associated with the first cell and a second downlink signal reception time associated with the second cell, or a combination thereof.

In some examples, the indication of the timing difference is received in a medium access control control element or in a measurement report in uplink control information.

FIG.12shows a diagram of a system1200including a device1205that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The device1205may be an example of or include the components of a device905, a device1005, or a network entity105as described herein. The device1205may communicate with one or more network entities105, one or more UEs115, or any combination thereof, which may include communications over one or more wired interfaces, over one or more wireless interfaces, or any combination thereof. The device1205may include components that support outputting and obtaining communications, such as a communications manager1220, a transceiver1210, an antenna1215, a memory1225, code1230, and a processor1235. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., a bus1240).

The transceiver1210may support bi-directional communications via wired links, wireless links, or both as described herein. In some examples, the transceiver1210may include a wired transceiver and may communicate bi-directionally with another wired transceiver. Additionally, or alternatively, in some examples, the transceiver1210may include a wireless transceiver and may communicate bi-directionally with another wireless transceiver. In some examples, the device1205may include one or more antennas1215, which may be capable of transmitting or receiving wireless transmissions (e.g., concurrently). The transceiver1210may also include a modem to modulate signals, to provide the modulated signals for transmission (e.g., by one or more antennas1215, by a wired transmitter), to receive modulated signals (e.g., from one or more antennas1215, from a wired receiver), and to demodulate signals. In some implementations, the transceiver1210may include one or more interfaces, such as one or more interfaces coupled with the one or more antennas1215that are configured to support various receiving or obtaining operations, or one or more interfaces coupled with the one or more antennas1215that are configured to support various transmitting or outputting operations, or a combination thereof. In some implementations, the transceiver1210may include or be configured for coupling with one or more processors or memory components that are operable to perform or support operations based on received or obtained information or signals, or to generate information or other signals for transmission or other outputting, or any combination thereof. In some implementations, the transceiver1210, or the transceiver1210and the one or more antennas1215, or the transceiver1210and the one or more antennas1215and one or more processors or memory components (for example, the processor1235, or the memory1225, or both), may be included in a chip or chip assembly that is installed in the device1205. The transceiver1210, or the transceiver1210and one or more antennas1215or wired interfaces, where applicable, may be an example of a transmitter915, a transmitter1015, a receiver910, a receiver1010, or any combination thereof or component thereof, as described herein. In some examples, the transceiver may be operable to support communications via one or more communications links (e.g., a communication link125, a backhaul communication link120, a midhaul communication link162, a fronthaul communication link168).

The memory1225may include RAM and ROM. The memory1225may store computer-readable, computer-executable code1230including instructions that, when executed by the processor1235, cause the device1205to perform various functions described herein. The code1230may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some cases, the code1230may not be directly executable by the processor1235but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, the memory1225may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor1235may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA, a microcontroller, a programmable logic device, discrete gate or transistor logic, a discrete hardware component, or any combination thereof). In some cases, the processor1235may be configured to operate a memory array using a memory controller. In some other cases, a memory controller may be integrated into the processor1235. The processor1235may be configured to execute computer-readable instructions stored in a memory (e.g., the memory1225) to cause the device1205to perform various functions (e.g., functions or tasks supporting UE assisted uplink synchronization for inter-cell mobility). For example, the device1205or a component of the device1205may include a processor1235and memory1225coupled with the processor1235, the processor1235and memory1225configured to perform various functions described herein. The processor1235may be an example of a cloud-computing platform (e.g., one or more physical nodes and supporting software such as operating systems, virtual machines, or container instances) that may host the functions (e.g., by executing code1230) to perform the functions of the device1205. The processor1235may be any one or more suitable processors capable of executing scripts or instructions of one or more software programs stored in the device1205(such as within the memory1225). In some implementations, the processor1235may be a component of a processing system. A processing system may generally refer to a system or series of machines or components that receives inputs and processes the inputs to produce a set of outputs (which may be passed to other systems or components of, for example, the device1205). For example, a processing system of the device1205may refer to a system including the various other components or subcomponents of the device1205, such as the processor1235, or the transceiver1210, or the communications manager1220, or other components or combinations of components of the device1205. The processing system of the device1205may interface with other components of the device1205, and may process information received from other components (such as inputs or signals) or output information to other components. For example, a chip or modem of the device1205may include a processing system and an interface to output information, or to obtain information, or both. The interface may be implemented as or otherwise include a first interface configured to output information and a second interface configured to obtain information. In some implementations, the first interface may refer to an interface between the processing system of the chip or modem and a transmitter, such that the device1205may transmit information output from the chip or modem. In some implementations, the second interface may refer to an interface between the processing system of the chip or modem and a receiver, such that the device1205may obtain information or signal inputs, and the information may be passed to the processing system. A person having ordinary skill in the art will readily recognize that the first interface also may obtain information or signal inputs, and the second interface also may output information or signal outputs.

In some examples, a bus1240may support communications of (e.g., within) a protocol layer of a protocol stack. In some examples, a bus1240may support communications associated with a logical channel of a protocol stack (e.g., between protocol layers of a protocol stack), which may include communications performed within a component of the device1205, or between different components of the device1205that may be co-located or located in different locations (e.g., where the device1205may refer to a system in which one or more of the communications manager1220, the transceiver1210, the memory1225, the code1230, and the processor1235may be located in one of the different components or divided between different components).

The communications manager1220may support wireless communication at a network entity in accordance with examples as disclosed herein. For example, the communications manager1220may be configured as or otherwise support a means for transmitting an indication of a set of cells configured for communications with a UE. The communications manager1220may be configured as or otherwise support a means for transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell. The communications manager1220may be configured as or otherwise support a means for receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.

By including or configuring the communications manager1220in accordance with examples as described herein, the device1205may support techniques for reduced processing, reduced power consumption, and more efficient utilization of communication resources. Because the device1205may receive timing differences between the timing advances at a UE115for communicating with a cell that is deactivated and timing differences at the UE115for communicating with a reference cell, the device1205may maintain a timing advance for the UE115to use to communicate with the cell. Thus, when the cell is activated, the device1205may signal the timing advance for the UE115to use to communicate with the cell, and the UE115may avoid performing a RACH procedure with the device1205to identify the timing advance (e.g., resulting in the reduced processing, reduced power consumption, and more efficient utilization of communication resources).

In some examples, the communications manager1220may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the transceiver1210, the one or more antennas1215(e.g., where applicable), or any combination thereof. Although the communications manager1220is illustrated as a separate component, in some examples, one or more functions described with reference to the communications manager1220may be supported by or performed by the processor1235, the memory1225, the code1230, the transceiver1210, or any combination thereof. For example, the code1230may include instructions executable by the processor1235to cause the device1205to perform various aspects of UE assisted uplink synchronization for inter-cell mobility as described herein, or the processor1235and the memory1225may be otherwise configured to perform or support such operations.

At1305, the method may include receiving an indication of a set of cells configured for communications with the UE. The operations of1305may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of1305may be performed by a cell configuration manager725as described with reference toFIG.7.

At1310, the method may include receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, where the first cell is activated and includes a reference cell, and the second cell is deactivated. The operations of1310may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of1310may be performed by a reference signal manager730as described with reference toFIG.7.

At1315, the method may include transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell. The operations of1315may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of1315may be performed by a timing advance manager735as described with reference toFIG.7.

FIG.14shows a flowchart illustrating a method1400that supports UE assisted uplink synchronization for inter-cell mobility in accordance with one or more aspects of the present disclosure. The operations of the method1400may be implemented by a network entity or its components as described herein. For example, the operations of the method1400may be performed by a network entity as described with reference toFIGS.1through4and9through12. In some examples, a network entity may execute a set of instructions to control the functional elements of the network entity to perform the described functions. Additionally, or alternatively, the network entity may perform aspects of the described functions using special-purpose hardware.

At1405, the method may include transmitting an indication of a set of cells configured for communications with a UE. The operations of1405may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of1405may be performed by a cell configuration manager1125as described with reference toFIG.11.

At1410, the method may include transmitting a first reference signal via a first cell of the set of cells, where the first cell is activated and includes a reference cell, and the first cell is different from a second, deactivated cell. The operations of1410may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of1410may be performed by a reference signal manager1130as described with reference toFIG.11.

At1415, the method may include receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell. The operations of1415may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of1415may be performed by a timing advance manager1135as described with reference toFIG.11.

The following provides an overview of aspects of the present disclosure:Aspect 1: A method for wireless communication at a UE, comprising: receiving an indication of a set of cells configured for communications with the UE; receiving a first reference signal from a first cell of the set of cells and a second reference signal from a second cell of the set of cells, wherein the first cell is activated and comprises a reference cell, and the second cell is deactivated; and transmitting an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.Aspect 2: The method of aspect 1, further comprising: receiving an indication that the second cell is activated; receiving an indication of the second timing advance for communicating with the second cell based at least in part on transmitting the timing difference; and communicating with the second cell using the second timing advance.Aspect 3: The method of any of aspects 1 through 2, wherein transmitting the indication of the timing difference comprises: transmitting a periodic transmission comprising the indication of the timing difference.Aspect 4: The method of aspect 3, further comprising: receiving an indication of a periodicity for transmitting periodic transmissions comprising indications of timing differences.Aspect 5: The method of any of aspects 1 through 4, wherein transmitting the indication of the timing difference comprises: transmitting an aperiodic transmission comprising the indication of the timing difference.Aspect 6: The method of aspect 5, further comprising: identifying one or more triggering conditions for transmitting the timing difference, wherein transmitting the aperiodic transmission is based at least in part on at least one of the one or more triggering conditions being satisfied.Aspect 7: The method of aspect 6, wherein the one or more triggering conditions comprise the timing difference satisfying a timing difference threshold, a change in the reference cell, or a combination thereof.Aspect 8: The method of any of aspects 6 through 7, further comprising: receiving an indication of the one or more triggering conditions for transmitting the timing difference.Aspect 9: The method of any of aspects 5 through 8, further comprising: receiving a request to transmit the timing difference, wherein transmitting the aperiodic transmission is based at least in part on receiving the request.Aspect 10: The method of any of aspects 5 through 9, further comprising: transmitting a plurality of timing differences between timing advances for communicating with the first cell and timing advances for communicating with the second cell, the plurality of timing differences comprising the timing difference between the first timing advance and the second timing advance.Aspect 11: The method of any of aspects 1 through 10, further comprising: receiving an indication that the first cell is the reference cell, wherein the first cell is selected as the reference cell based at least in part on cell quality, cell functionality, or a combination thereofAspect 12: The method of any of aspects 1 through 11, further comprising: receiving an indication of a plurality of configurations for the UE to use to transmit the timing difference; and receiving a control message indicating a configuration of the plurality of configurations for the UE to use to transmit the timing difference, wherein transmitting the indication of the timing difference is based at least in part on the configuration.Aspect 13: The method of any of aspects 1 through 12, wherein the timing difference between the first timing advance and the second timing advance is based at least in part on a downlink propagation delay difference between a first downlink propagation delay associated with the first cell and a second downlink propagation delay associated with the second cell, a difference between a first downlink signal reception time associated with the first cell and a second downlink signal reception time associated with the second cell, or a combination thereof.Aspect 14: The method of any of aspects 1 through 13, wherein the indication of the timing difference is transmitted in a medium access control control element or in a measurement report in uplink control information.Aspect 15: A method for wireless communication at a network entity, comprising: transmitting an indication of a set of cells configured for communications with a UE; transmitting a first reference signal via a first cell of the set of cells, wherein the first cell is activated and comprises a reference cell, and the first cell is different from a second, deactivated cell; and receiving an indication of a timing difference between a first timing advance for communicating with the first cell and a second timing advance for communicating with the second cell.Aspect 16: The method of aspect 15, further comprising: transmitting an indication that the second cell is activated; and transmitting an indication of the second timing advance for communicating with the second cell based at least in part on receiving the timing difference.Aspect 17: The method of any of aspects 15 through 16, wherein receiving the indication of the timing difference comprises: receiving a periodic transmission comprising the indication of the timing difference.Aspect 18: The method of aspect 17, further comprising: transmitting an indication of a periodicity for periodic transmissions from the UE comprising indications of timing differences.Aspect 19: The method of any of aspects 15 through 18, wherein receiving the indication of the timing difference comprises: receiving an aperiodic transmission comprising the indication of the timing difference.Aspect 20: The method of aspect 19, further comprising: transmitting an indication of one or more triggering conditions for the UE to transmit the timing difference, wherein receiving the aperiodic transmission is based at least in part on at least one of the one or more triggering conditions being satisfied.Aspect 21: The method of aspect 20, wherein the one or more triggering conditions comprises the timing difference satisfying a timing difference threshold, a change in the reference cell, or a combination thereof.Aspect 22: The method of any of aspects 19 through 21, further comprising: transmitting a request for the UE to transmit the timing difference, wherein receiving the aperiodic transmission is based at least in part on transmitting the request.Aspect 23: The method of any of aspects 19 through 22, further comprising: receiving a plurality of timing differences between timing advances for communicating with the first cell and timing advances for communicating with the second cell, the plurality of timing differences comprising the timing difference between the first timing advance and the second timing advance.Aspect 24: The method of any of aspects 15 through 23, further comprising: transmitting an indication that the first cell is the reference cell, wherein the first cell is selected as the reference cell based at least in part on cell quality, cell functionality, or a combination thereofAspect 25: The method of any of aspects 15 through 24, further comprising: transmitting an indication of a plurality of configurations for the UE to use to transmit the timing difference; and transmitting a control message indicating a configuration of the plurality of configurations for the UE to use to transmit the timing difference, wherein receiving the indication of the timing difference is based at least in part on the configuration.Aspect 26: The method of any of aspects 15 through 25, wherein the timing difference between the first timing advance and the second timing advance is based at least in part on a downlink propagation delay difference between a first downlink propagation delay associated with the first cell and a second downlink propagation delay associated with the second cell, a difference between a first downlink signal reception time associated with the first cell and a second downlink signal reception time associated with the second cell, or a combination thereofAspect 27: The method of any of aspects 15 through 26, wherein the indication of the timing difference is received in a medium access control control element or in a measurement report in uplink control information.Aspect 28: An apparatus for wireless communication at a UE, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of aspects 1 through 14.Aspect 29: An apparatus for wireless communication at a UE, comprising at least one means for performing a method of any of aspects 1 through 14.Aspect 30: A non-transitory computer-readable medium storing code for wireless communication at a UE, the code comprising instructions executable by a processor to perform a method of any of aspects 1 through 14.Aspect 31: An apparatus for wireless communication at a network entity, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of aspects 15 through 27.Aspect 32: An apparatus for wireless communication at a network entity, comprising at least one means for performing a method of any of aspects 15 through 27.Aspect 33: A non-transitory computer-readable medium storing code for wireless communication at a network entity, the code comprising instructions executable by a processor to perform a method of any of aspects 15 through 27.