Methods for layer 3 measurements based layer 1 / layer2 triggered mobility cross-reference to related applications

Abstract

An apparatus including at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

Description

METHODS FOR LAYER 3 MEASUREMENTS BASED LAYER 1 / LAYER2 TRIGGERED MOBILITY CROSS-REFERENCE TO RELATED APPLICATIONSTECHNICAL FIELD

[0001] The example and non-limiting embodiments relate generally to user equipment mobility and, more particularly, to lower layer triggered mobility.BRIEF DESCRIPTION OF PRIOR DEVELOPMENTS

[0002] Lower layer triggered mobility (LTM) is a cell switch procedure, where a user equipment’s serving cell (such as a PCell or a PSCell for example) is switched by a network by sending an LTM cell switch command.SUMMARY OF THE INVENTION

[0003] The following summary is merely intended to be an example. The summary is not intended to limit the scope of the claims.

[0004] In accordance with one aspect, an example apparatus is provided including at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

[0005] In accordance with another aspect, an example method is provided comprising: determining, by an apparatus, to prepare at least one device for lower layer triggered mobility; and sending information from an apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus

[0006] In accordance with another aspect, an example apparatus is provided comprising: means for determining to prepare at least one device for lower layer triggered mobility; and means for sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

[0007] In accordance with another aspect, an example apparatus is provided with a non- transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

[0008] In accordance with another aspect, an example apparatus is provided comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

[0009] In accordance with another aspect, an example method is provided comprising: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

[0010] In accordance with another aspect, an example apparatus is provided comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: anearly downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0011] In accordance with another aspect, an example method is provided comprising: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0012] In accordance with another aspect, an example apparatus is provided comprising: means for receiving lower layer triggered mobility information from a centralized unit; and means for determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0013] In accordance with another aspect, an example apparatus is provided with a non- transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0014] In accordance with another aspect, an example apparatus is provided comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0015] In accordance with another aspect, an example method is provided comprising: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0016] In accordance with another aspect, an example apparatus is provided comprising: means for receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and means for, based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0017] In accordance with another aspect, an example non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0018] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are provided in subject matter of the dependent claims.BRIEF DESCRIPTION OF DRAWINGS

[0019] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein:

[0020] FIG. l is a block diagram of one possible and non-limiting example system in which the example embodiments may be practiced;

[0021] FIG. 2 is a signaling diagram illustrating an example use of a conventional lower layer triggered mobility (LTM) in Rel. 18;

[0022] FIG. 3 is a signaling diagram illustrating an example use of lower layer triggered mobility as described herein;

[0023] FIG. 4 is a diagram illustrating an example method;

[0024] FIG. 5 is a diagram illustrating an example method;

[0025] FIG. 6 is a diagram illustrating an example method;

[0026] FIG. 7 is a diagram illustrating an example method.DETAILED DESCRIPTION

[0027] The following abbreviations that may be found in the specification and / or the drawing figures are defined as follows:3 GPP third generation partnership project5G fifth generation5GC 5G core networkAMF access and mobility management functionCE connection elementCFRA contention free random accessCHO conditional handoverCSC cell switch commandCU centralized unitDL downlinkDU distributed unit eNB (or eNodeB) evolved Node B (e.g., an LTE base station)EN-DC E-UTRA-NR dual connectivity en-gNB or En-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as secondary node in EN-DCE-UTRA evolved universal terrestrial radio access, i.e., the LTE radio access technologyFR1 frequency range 1FR2 frequency range 2 gNB (or gNodeB) base station for 5G / NR, i.e., a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GCHO handoverID identificationI / F interfaceLI layer 1L2 layer 2L3 layer 3LTE long term evolutionLTM lower layer triggered mobilityMAC medium access controlMME mobility management entity ng or NG next generation ng-eNB or NG-eNB next generation eNBNR new radioN / W or NW networkPCell primary cellPDCCH physical downlink control channelPDCP packet data convergence protocolPHY physical layerPSCell special cellQoS quality of serviceRACH random access channelRAN radio access networkRel releaseRel. 18 release 18RLC radio link controlRRH remote radio headRRC radio resource controlRU radio unitRx receiverSDAP service data adaptation protocolSGW serving gatewaySMF session management functionSSB synchronization signal blockTA timing advanceTCI transmission configuration indicationTS technical specificationTx transmitterUE user equipment (e.g., a wireless, typically mobile device)UL uplinkUPF user plane function

[0028] Turning to FIG. 1, this figure shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. Examples of network equipment, network device, or a network entity might be understood to include, at least part of, a transmission reception point or a cell or a gNB or node for example. In the example of FIG. 1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, comprising one of or both parts 140-1 and / or 140-2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0029] The RAN node 170 in this example is a base station that provides access by wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or a ng-eNB. A gNB is a node providingNR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the Fl interface connected with the gNB-DU. The Fl interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB- DU. The gNB-DU terminates the Fl interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.

[0030] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W I / F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory / memories and processor(s), and / or other hardware, but these are not shown.

[0031] The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and / or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit orthrough other hardware such as a programmable gate array. In another example, the module 150 may be implemented as module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0032] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0033] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH / DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU) of the RAN node 170 to the RRH / DU 195. Reference 198 also indicates those suitable network link(s).

[0034] It is noted that description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell will perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one- third of a 360-degree area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So, if there are three 120-degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0035] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and / or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(S)) and / or user plane functions (UPF(s)) and / or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity ) / SGW (Serving Gateway) functionality. These are merely exemplary functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to a network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / W I / F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the network element 190 to perform one or more operations.

[0036] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0037] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the localtechnical environment, and may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, and other functions as described herein.

[0038] In general, the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

[0039] LTM is a cell switch procedure, where a UE’s serving cell may be switched by a network by sending an LTM cell switch command. An LTM switch command is currently assumed delivered by MAC signaling using a MAC CE. Thus, a conventional LTM switch command is not delivered to the UE using RRC signaling. Conventionally, an LTM cell switch decision is based on measurements (for example LI measurements) that are performed and reported (for example LI measurement report) by the UE. Measurements and reporting are based on LTM candidate cell configuration provided by the network for one or more LTM candidate cells. An LTM candidate cell may be one or more neighboring cells or a UE’ s current serving cells, such as an SCell for example.

[0040] In Rel. 18, LTM measurements on a neighboring candidate cell are performed using SSBs transmitted by the candidate cell for which the SSB configuration is provided to the UE. Before the cell switch, the network may optionally activate one or more TCI state(s) for one or more candidate cells. Once a candidate cell TCI state is activated, the UE may start tracking the time / frequency synchronization using the reference signals associated with the activated TCI state(s). The UE may also perform early UL synchronization before the cell switch if this is requested by the network. Fig. 2 illustrates an example signaling diagram with an LTMprocedure based on TS 38.300 V18.0.0 (signaling procedure for LTM in Rel. 18). Rel. 18 only covers Intra-CU LTM handovers. As can be seen in Fig. 2, at step 5 for the LTM execution an LI measurement report is sent from the UE to the base station (gNB), and the gNB can send a cell switch command via a MAC CE to the UE as illustrated at step 6. This conventional procedure for LTM generally comprises the following steps shown in Fig. 2:1. The UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates LTM preparation.2. The gNB transmits an RRCReconfiguration message to the UE including the LTM candidate configurations.3. The UE stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB.4a. The UE performs DL synchronization with the candidate cell(s) before receiving the cell switch command.4b. UE performs early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command as specified in clause 9.2.6 [38.300], This is done via CFRA triggered by a PDCCH order from the source cell, following which the UE sends preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the UE does not receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE does not maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity.5. The UE performs LI measurements on the configured candidate cell(s) and transmits LI measurement reports to the gNB. LI measurement should be performed as long as RRC reconfiguration (step 2) is applicable.6. The gNB decides to execute cell switch to a target cell and transmits a MAC CE triggering cell switch by including the candidate configuration index of the targetcell. The UE switches to the target cell and applies the configuration indicated by candidate configuration index.7. The UE performs the random-access procedure towards the target cell, if UE does not have valid TA of the target cell as specified in clause 6.1.3.75 of TS 38.321.8. The UE completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell. If the UE has performed a RA procedure in step 7 the UE considers that LTM cell switch execution is successfully completed when the random-access procedure is successfully completed. For RACH-less LTM, the UE considers that LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data.

[0041] The steps 4-8 can be performed multiple times for subsequent LTM using the LTM candidate configuration(s) provided in step 2. The procedure over the air interface described above is applicable to both intra-gNB-DU LTM and inter-gNB-DU LTM. The overall LTM procedures over Fl -C interface are captured in TS 38.401.

[0042] In an R2 -2404014, RAN2 had asked RAN4 the following question:0043] In the reply, R4-2410303, RAN4 had the following remarks for RAN2:

[0044] Thus, for Frequency Range 1 (FR1) based deployments, LTM relevant procedures might be able to be carried out without activating any additional LTM specific LI measurements on the candidate cells at the UE.

[0045] As described herein, rather than use of an LI or L2 measurement, an exchange of L3 measurements or LTM target cell information from a CU to source DU may be used allow the source DU to make a decision on LTM considering the L3 measurements or LTM target cell information as additional criteria for switching decision. Not all L3 measurements-based LTM procedures may be optimum in terms of handover interruption time and reliability of switching. Hence, with features as described herein, additional enhancements may also be provided to enhance use of an L3 measurements-based LTM.

[0046] Considering the recent agreement in RAN4, it seems that (at least for FR1) the UE may not support LI measurements for LTM for certain frequencies, but supports LTM switching (step 6 in FIG. 2) and early DL synchronization or / and early UL synchronization (step 4a and step 4b in FIG. 2) functionality. With early DL or / and UL synchronization, when the UE acquires DL or / and UL synchronization before the cell switch, the UE is not required time for these processes in the cell switch delay (i.e. the UE cell switch delay may omit one or more delay components related to the DL / UL synchronization processes).

[0047] To have the benefits of early DL or / and UL synchronization towards candidate cells for which that LI measurements and reports are not activated / supported, methods / procedures as described herein may be used to trigger LTM based on L3 measurements. This may be provided for split architecture-based NW deployment, where the CU and the DU are split because, with such a split architecture-based NW deployment, L3 measurements are sent by the UE using RRC signaling to the CU; however, most of the LTM procedure decisions, (i.e., dynamic triggering of early DL and / or UL synchronization, or cell switch decision) are performed by the source DU. It is also beneficial to trigger L3 measurements-based LTM ifthe NW observes that the LI measurement results are not stable to be considered for switching or if the UE does not support performing LI measurements for the LTM candidate cells. With features as described herein, when LTM is triggered at least based on L3 measurements, enhancements may be provided for:• signaling needed for doing early TCI state activation / deactivation, where early TCI activation / deactivation is used to carry out early DL synchronization.• signaling exchange needed to trigger early PDCCH-ordered RACH, where PDCCH ordered RACH is used to carry out early UL synchronization.• signaling needed to trigger cell switch.

[0048] It should be noted that for both an early synchronization procedure and a LTM triggering procedure, either of the separate procedures can be triggered at least based on L3 measurements.

[0049] The L3 measurements referred to herein may be conventional legacy L3 measurements, or may comprise additional or newL3 measurements configured and performed on neighboring cells including the LTM candidate cells.

[0050] Features as described herein may be provided in different ways. For example, with one type of example the CU may provide the DU with L3 measurements by the UE. Although a UE might use a DU to convey L3 measurements to the CU, that conveyance may be transparent to the DU. In other words, even though the UE might send L3 measurements to the DU, where the DU subsequently sends those L3 measurements to the CU, the DU would normally not be able to use the L3 measurements from the UE. Thus, the CU may send the L3 measurements to the DU for the DU to subsequently use those L3 measurements. As another example, the CU might provide the DU with information or instructions without necessarily providing the DU with L3 measurements by the UE. The DU may be configured to perform the LTM procedure without directly using the L3 measurements of the UE. Two non-limiting examples are described below noted as Example 1 and Example 2.

[0051] Example 1

[0052] This example may comprise a method for a CU assisted LTM procedure at a DU with use of L3 Measurements at the DU. The NW may configure the UE for separate events for L3 measurements related to early DL, early UL, and / or cell-switching for the UE. This configuration may enable the CU to determine when to coordinate with the source DU to perform one or more of these operations.

[0053] When the CU receives the L3 measurements from the UE, these measurements may be forwarded to the source DU. In one type of example, when the measurement (i.e., beam level L3 measurements) result is passed to the source DU from the CU, one flag may be introduced to indicate the DU action such as, for example, whether to trigger early DL synchronization (TCI state activation / deactivation), early UL synchronization, or / and CSC or TCI state activation / deactivation. In one type of example, a multi-bit flag may be used to indicate a combination of one or more operations such as, for example, both early DL synchronization and early UL synchronization. The source DU may trigger appropriate procedures such as, for example, candidate TCI activation / deactivation after receiving a flag indicating early DL synchronization, PDCCH ordered RACH after receiving a flag indicating early UL synchronization, and / or cell switch after receiving a flag indicating the cell switch. The source cell may select appropriate configuration such as, for example, a candidate cell and associated candidate TCI state(s) for early DL synchronization, a candidate cell and SSB index for early UL synchronization, or / and a candidate cell, TCI state, SSB index (if CFRA RACH procedure needs to be triggered) for cell switch command, based on the L3 measurements received from the CU. The source CU can choose to instruct DU1 (i.e., source DU) to perform these procedures (i.e., early sync and / or cell switch) for cells that are still under DU1, but are different from the serving cell, or for cells under another DU (e.g., DU2 or DU3). The source DU, i.e., DUI, can have cells I (serving cell) and 2 (LTM candidate). The source CU can choose to instruct DUI to activate TCI states for cell 2, or perform early TA acquisition, or switch the UE to cell 2. LTM procedures may be triggered based on a latest measurement event and SSB based switching will, thus, be accurate.

[0054] Referring also to FIG. 3, an example signaling diagram is shown for the UE 110, the DU I95-I which is a source DU, the CU 196 and two target DUs 195-2, 195-3. FIG. I shows the DU and the CU at a common node. This may be the case for the DU I95-I and CU 196, but the DU I95-I and CU 196 in this example are split at different spaced locations.

[0055] At steps 1- 3, the UE 110 may send the L3 measurement report to the DU 195-1, which forwards it to the CU 196. In step 3, CU 196 may decide to trigger LTM, and start an LTM candidate cell preparation.

[0056] At step 4 and 5 the CU 196 may send a UE Context Setup Request to the target DUs 195-1, 195-3 for the preparation of the target cells. As part of this request to the target DUs, the CU 196 may include an indication that LTM switching will be triggered based on L3 measurements. In case only L3 measurements is only possible, the CU may indicate that the LTM reporting configuration is not needed in the candidate cells for LTM.

[0057] At steps 6 and 7 the target DUs 195-2, 195-3 may send the lower layer configuration to the CU with their UE context setup responses. The target DUs can use the information of whether LTM will be triggered only through L3 measurements to avoid mapping its LI Reporting configuration to the candidate cells.

[0058] At step 8, the CU 196 may send a UE Context Modification Request to source DU 195-1. This UE Context Modification Request may indicate that LTM switching is based on L3 measurements.

[0059] At step 9 the source DU may send a UE Context Modification Response message to the CU 196. The source DU can use the information of whether LTM will be triggered only through L3 measurements to avoid mapping its LI Reporting configuration to the candidate cells.

[0060] At step 10, the CU 196 may prepare the RRC Configuration and provides it to the UE. The UE may store the configuration of LTM candidate target cell(s) and transmits a RRCReconfigurationComplete message to the CU as indicated with step 11. In another example implementation, the CU 196 may provide both LI and L3 measurement and reporting configurations for LTM. The RRC configuration may contain L3 measurement and reporting configurations prepared for LTM such as, for example, new events for reporting which can indicate to the CU about early DL synchronization, early UL synchronization, or CSC for LTM.

[0061] With step 12 -14 the UE 110 may measure the candidate cells and forwards the measurement reports to the CU 196 through the serving DU 195-1.

[0062] With step 15-16, the serving CU 196 may decide to trigger at least one of early DL, early UL, or / and CSC based on the L3 measurement and inform the serving DU 195-1 about the action it can take. As an example, the CU may forward at least one or more of the following:• TCI state or SSB index and LTM candidate ID for early downlink synchronization,• SSB index and LTM candidate cell ID for early UL synchronization, or• TCI state / SSB index and LTM candidate ID along with SSB index (optional for CFRA RACH based LTM) for the DU to include in the LTM cell switch command.

[0063] The above-described example illustrates how, in one type of example, the L3 measurements may be used to provide lower layer triggered mobility. In the above example, the CU sends the L3 measurement information to the source DU. In an alternate example, as described below, the CU might not send the L3 measurement information to the source DU. The CU may provide the TCI states that should be activated / deactivated for the UE, and indication to trigger PDCCH order for early TA acquisition for an LTM candidate cell and / or cell switch command for an LTM candidate cell.

[0064] Example 2

[0065] In this non-limiting example, the CU 196 may control one or more actions at the source DU 195-1 without the CU sending the L3 measurements to the source DU 106-1. In this example, the CU provides LTM-Assistance-information instead of the L3 measurements. The LTM-Assistance-information may comprise an indication regarding one or more actions and one or more candidate target cell(s). The one or more actions may be in regard to early UL synchronization, early TCI state activation, or / and cell switch for example.

[0066] In one type of example, based on the L3 measurement from the UE (e.g., beam level L3 measurements) received by the CU, the CU may send to the source DU: a) one or more candidate TCI states and candidate cell ID for early DL synchronization, and / or b) one or more SSB indices and candidate cell ID for early UL synchronization, or / andc) candidate TCI state and candidate cell ID along with SSB index (optional for CFRA RACH-based LTM) for CSC.

[0067] In one example, for early DL synchronization (for early TCI activation or cell switch) SSB index along with candidate cell ID can also be exchanged. The source DU may determine appropriate TCI state(s) based on the SSB index information to activate or / and indicate. Source DU indicates to the UE the TCI states that should be activated / deactivated for a certain LTM candidate cell ID.

[0068] In one example, more than one candidate SSB indices or TCI indices associated with one or more candidate cells IDs may be shared with the source DU by the CU. The source DU may select one or more from the given set and trigger relevant procedure. For example, the CU may provide SSB 1, SSB 2 of candidate cell 1, and SSB 3, SSB 5 of candidate cell 2 for early UL synchronization. The source DU triggers PDCCH order for early TA acquisition. For TCI state activation / deactivation the source DU sends an early TCI state activation / deactivation MAC CE to the UE. The source DU may decide to trigger PDCCH ordered RACH with SSB 1 of candidate cell 1 and SSB 5 of candidate cell 2.

[0069] In one example, when the source CU provides more than one option, a priority order, such as based on the measurements reported by the UE for example, may also be sent to the source DU. This priority order or priority information can be used by the source DU to select appropriate parameters (such as SSB indices or TCI state indices for example) to trigger early DL, early UL, or a cell switch.

[0070] The source DU may trigger appropriate procedures such as, for example: candidate TCI activation / deactivation after receiving the (a), PDCCH ordered RACH after receiving the (b), CSC after receiving the (c) using the associated information received from the CU. The source DU may follow the indication from the CU and its own internal information.

[0071] An additional method may be provided where there has been a prior single (single instance) L3 measurement results forwarding to DU. The CU may have previously forwarded L3 measurements to the DU for the DU to consider this information for LTM related actions. If the DU needs to complete an early uplink synchronization step prior to switching, there may be a delay in completing an early uplink synch. In such a case, the DU may trigger an LTMswitching command without TCI state to allow the UE to synchronize to the best SSB at the time of switching.

[0072] An example embodiment may be provided with an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

[0073] The information may comprise the at least one L3 measurement. The information may comprise an indication for the at least one device to trigger a user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch. The indication may comprise one of: a single bit flag, or a multi -bit flag. The indication for the at least one device to trigger the early downlink synchronization may be for a transmission configuration indication state activation or deactivation. The indication for the at least one device to trigger the early uplink synchronization may comprise an indication for a physical downlink control channel order for triggering an early random access channel for the user equipment. The indication for the at least one device to trigger the cell switch may be for a cell switch command. This indication may also contain information about the candidate cell ID, e.g., for which the UE should perform early TCI state activation / deactivation, early TA acquisition or cell switch. The information may comprise an indication for the at least one device to trigger the user equipment to perform at least one of the early downlink synchronization or the early uplink synchronization. The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving an uplink radio resource control transfer message, where the uplink radio resource control message transfer message comprises an L3 measurement report. The instructions, when executed with the at least one processor, may cause the apparatus to perform: sending, based at least partially on the received uplink radio resource control transfer message, lower layer triggered mobility handover information. The lower layer triggered mobility handover information may comprise at least one of: an indication for triggering an early TA acquisition, an indication for triggering an early transmission configuration indication activation or deactivation, or an indication for triggeringa cell switch. The at least one device may comprise a target distributed unit, and where the sending of the information comprises sending a user equipment context setup request indicating that the lower layer triggered mobility is to be based on a L3 measurement. The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving, based at least partially on the sent user equipment context setup request, a user equipment context setup response with a lower layer triggered mobility L3 measurement configuration. The instructions, when executed with the at least one processor, may cause the apparatus to perform: sending, based at least partially on the received user equipment context setup response, a user equipment context modification request for a source distributed unit, where the user equipment context modification request comprises an indication that the lower layer triggered mobility is to be based on a L3 measurement. The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving, based at least partially on the sent user equipment context modification request, a user equipment context modification response. The instructions, when executed with the at least one processor, may cause the apparatus to perform: sending a radio resource control reconfiguration message for the user equipment, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration. The instructions, when executed with the at least one processor, may cause the apparatus to perform: sending a radio resource control reconfiguration message for a source distributed unit, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration. The instructions, when executed with the at least one processor, may cause the apparatus to perform: sending the at least one L3 measurement of the user equipment received by the apparatus to a source distribution unit. The information may comprise lower layer triggered mobility information which does not include the at least one L3 measurement. The lower layer triggered mobility information may comprise at least one of: an indication of at least one possible action to be performed by the at least one device, or determination information for the at least one device to determine the at least one possible action to be performed by the at least one device. For the usage of LTM assistance information, the source DU can choose to ignore it. The at least one possible action comprises at least one of: one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization, or a candidate transmission configuration indicationstate and candidate cell ID with a synchronization signal block index for a cell switch command. For the early downlink synchronization, the lower layer triggered mobility information may comprise a synchronization signal block index and a candidate cell ID. The lower layer triggered mobility information may comprise an indication for the at least one device to trigger a user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch. The instructions, when executed with the at least one processor, may cause the apparatus to perform: for when the indication for the at least one device to trigger the user equipment to perform the early downlink synchronization, the indication comprises at least one transmission configuration indication state, and for when the indication for the at least one device to trigger the user equipment to perform the early uplink synchronization, the indication comprises at least one synchronization signal block indices and at least one candidate cell ID. The lower layer triggered mobility information may comprise at least one of: more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells. The lower layer triggered mobility information may comprise a plurality of options to be performed by the at least one device and a priority order for determining use of the options. The lower layer triggered mobility information may comprise an instruction for the at least one device to select one or more parameters for determining triggering of at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or a cell switch.

[0074] Referring also to FIG. 4, an example embodiment may be provided with a method comprising: determining, by an apparatus, to prepare at least one device for lower layer triggered mobility as illustrated with block 402; and sending information from an apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility as illustrated with block 404, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus. The information may comprise the at least one L3 measurement. The information may comprise an indication for the at least one device to trigger the user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch. The indication may comprise one of: a single bit flag, or a multi-bit flag. The indication for the at least one device to trigger the early downlinksynchronization may be for a transmission configuration indication state activation or deactivation. The indication for the at least one device to trigger the early uplink synchronization may comprise an indication for a physical downlink control channel order for triggering an early random access channel for the user equipment. The indication for the at least one device to trigger the cell switch may be for a cell switch command. The information may comprise an indication for the at least one device to trigger the user equipment to perform at least one of the early downlink synchronization or the early uplink synchronization. The method may further comprise receiving an uplink radio resource control transfer message, where the uplink radio resource control message transfer message comprises an L3 measurement report. The method may further comprise sending, based at least partially on the received uplink radio resource control transfer message, lower layer triggered mobility handover information. The lower layer triggered mobility handover information may comprise at least one of: an indication for triggering an early TA acquisition, an indication for triggering an early transmission configuration indication activation or deactivation, or an indication for triggering a cell switch. The at least one device may comprise a target distributed unit, and where the sending of the information comprises sending a user equipment context setup request indicating that the lower layer triggered mobility is to be based on a L3 measurement. The method may further comprise receiving, based at least partially on the sent user equipment context setup request, a user equipment context setup response with a lower layer triggered mobility L3 measurement configuration. The method may further comprise sending, based at least partially on the received user equipment context setup response, a user equipment context modification request for a source distributed unit, where the user equipment context modification request comprises an indication that the lower layer triggered mobility is to be based on a L3 measurement. The method may further comprise receiving, based at least partially on the sent user equipment context modification request, a user equipment context modification response. The method may further comprise sending a radio resource control reconfiguration message for the user equipment, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration. The method may further comprise sending a radio resource control reconfiguration message for a source distributed unit, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration. The method may further comprise sending the at least one L3 measurement ofthe user equipment received by the apparatus to a source distribution unit. The information may comprise lower layer triggered mobility information which does not include the at least one L3 measurement. The lower layer triggered mobility information may comprise at least one of: an indication of at least one possible action to be performed by the at least one device, or determination information for the at least one device to determine the at least one possible action to be performed by the at least one device. The at least one possible action may comprise at least one of: one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command. For the early downlink synchronization, the lower layer triggered mobility information may comprise a synchronization signal block index and a candidate cell ID. The lower layer triggered mobility information may comprise an indication for the at least one device to trigger a user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch. The method may further comprise for when the indication for the at least one device to trigger the user equipment to perform the early downlink synchronization, the indication comprises at least one transmission configuration indication state, and for when the indication for the at least one device to trigger the user equipment to perform the early uplink synchronization, the indication comprises at least one synchronization signal block indices and at least one candidate cell ID. The lower layer triggered mobility information may comprise at least one of: more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells. The lower layer triggered mobility information may comprise a plurality of options to be performed by the at least one device and a priority order for determining use of the options. The lower layer triggered mobility information may comprise an instruction for the at least one device to select one or more parameters for determining triggering of at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or a cell switch.

[0075] An example embodiment may be provided with an apparatus comprising: means for determining to prepare at least one device for lower layer triggered mobility; and means for sending information from the apparatus based on the determination to prepare the at least onedevice for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

[0076] An example embodiment may be provided with an apparatus comprising a non- transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

[0077] An example embodiment may be provided with an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement. The receiving of the radio resource control reconfiguration message may comprise the triggered mobility L3 measurement configuration is from a centralized unit, and the sending of the radio resource control measurement report is for a source distributed unit.

[0078] Referring also to FIG. 5, an example embodiment may be provided with a method comprising: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration as illustrated with block 502; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement as illustrated with block 504.

[0079] An example embodiment may be provided with an apparatus comprising: means for receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and means for sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

[0080] An example embodiment may be provided with an apparatus comprising a non- transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

[0081] An example embodiment may be provided with an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0082] The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving a user equipment context modification request, where the user equipment context modification request comprises an indication that a lower layer triggered mobility is to be based on at least one L3 measurement. The instructions, when executed with the at least one processor, may cause the apparatus to perform: sending, based at least partially on the received user equipment context modification request, a user equipment context modification response for a centralized unit. The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving, based at least partially on the sending of the user equipment context modification response, a radio resource control reconfiguration message. The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving a radio resource control reconfiguration complete message from a user equipment, where the radio resource control reconfiguration complete message is based on the radio resource control reconfiguration message. The instructions, when executed with the at least one processor, may cause the apparatus to perform: receiving a radio resource control measurement report from a user equipment; and sending, based at least partially on the received radio resource control measurement report, an uplink radio resource control transfer message for a centralized unit, where the uplink radio resource control transfer message comprises the received radio resource control measurement report, and where thereceived radio resource control measurement report comprises L3 measurement information measured by the user equipment. The determining to trigger may be based, at least partially, on at least one of: an indication, received by the apparatus, of at least one possible action to be performed, or determination information, received by the apparatus, to determine the at least one possible action to be performed. The at least one possible action may comprise at least one of: one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization procedure, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization procedure, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command. For the early downlink synchronization, the lower layer triggered mobility information may comprise a synchronization signal block index and a candidate cell ID. The lower layer triggered mobility information may comprise at least one of: more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells. The lower layer triggered mobility information may comprise a plurality of options to be performed by the apparatus and a priority order for determining use of the options. The lower layer triggered mobility information may comprise an instruction for the apparatus to select one or more parameters for determining triggering of at least one of: the early downlink synchronization procedure, the early uplink synchronization procedure, or the cell switch.

[0083] Referring also to FIG. 6, an example embodiment may be provided with a method comprising: receiving lower layer triggered mobility information from a centralized unit as illustrated with block 602; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command as illustrated with block 604. The method may further comprise receiving a user equipment context modification request, where the user equipment context modification request comprises an indication that a lower layer triggered mobility is to be based on at least one L3 measurement. The method may further comprise sending, based at least partially on the received user equipment context modification request, a user equipment context modification response for a centralized unit. The method may further comprise receiving, based at least partially on the sending of the user equipment context modification response, a radio resourcecontrol reconfiguration message. The method may further comprise receiving a radio resource control reconfiguration complete message from a user equipment, where the radio resource control reconfiguration complete message is based on the radio resource control reconfiguration message. The method may further comprise receiving a radio resource control measurement report from a user equipment; and sending, based at least partially on the received radio resource control measurement report, an uplink radio resource control transfer message for a centralized unit, where the uplink radio resource control transfer message comprises the received radio resource control measurement report, and where the received radio resource control measurement report comprises L3 measurement information measured by the user equipment. The determining to trigger may be based, at least partially, on at least one of an indication, received by the apparatus, of at least one possible action to be performed, or determination information, received by the apparatus, to determine the at least one possible action to be performed. The at least one possible action may comprise at least one of one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization procedure, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization procedure, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command. For the early downlink synchronization, the lower layer triggered mobility information may comprise a synchronization signal block index and a candidate cell ID. The lower layer triggered mobility information may comprise at least one of more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells. The lower layer triggered mobility information may comprise a plurality of options to be performed by the apparatus and a priority order for determining use of the options. The lower layer triggered mobility information may comprise an instruction for the apparatus to select one or more parameters for determining triggering of at least one of the early downlink synchronization procedure, the early uplink synchronization procedure, or the cell switch.

[0084] An example embodiment may be provided with an apparatus comprising: means for receiving lower layer triggered mobility information from a centralized unit; and means for determining, based at least partially on the received lower layer triggered mobility information,to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0085] An example embodiment may be provided with an apparatus comprising a non- transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

[0086] An example embodiment may be provided with an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0087] Referring also to FIG. 7, an example embodiment may be provided with a method comprising: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement as illustrated with block 702; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration as illustrated with block 704.

[0088] An example embodiment may be provided with an apparatus comprising: means for receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and means for, based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0089] An example embodiment may be provided with an apparatus comprising a non- transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at leastpartially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

[0090] As used herein the term “lower layer triggered mobility” generally means a triggered mobility with use of information regarding a lower layer. Lower layers are well known such as, for example, layer 1 (LI), layer 2 (L2) and layer 3 (L3). In some cases in the past L3 has not quite been regarded as a lower layer, though it has depended on the protocol that was being considered. In the past, L1 / L2 Triggered Mobility has been used as a term for lower layer triggered mobility. In other words, LTM has meant L1 / L2 triggered mobility. For example, Release 18 has introduced L1 / L2 triggered mobility to enable a serving cell change via LI or L2 signaling, while keeping configuration of the upper layers and / or minimizing changes of configuration of the lower layers. Thus, as used herein “L1 / L2 triggered mobility’ is a form of “lower layer triggered mobility”. In other words, “lower layer triggered mobility” is a broad term which may comprise “L1 / L2 triggered mobility”, but is not necessarily limited to L1 / L2 triggered mobility.

[0091] In examples herein, L3 measurement information measured by the UE is lower layer information which is used. In one type of example, L3 measurement information could be used in combination with LI or L2 measurement information for the LTM procedure. For example, in a situation where LI measurement information is present, but is not stable enough to be considered for switching by itself, both LI and L3 measurement information might be used. The CU and / or the source DU may be configured to select whether to use only LI measurements, or only L3 measurements, or both LI and L3 measurements.

[0092] Features as described herein may comprise receiving L3 measurements from the UE by a CU, where the CU then decides to trigger LTM based on L3 measurements and provides to the DU at least one candidate target cell. This decision or determination by the CU may comprise a determination that an LI measurement is not available or not sufficiently stable to be used for LTM. The CU may indicate to DU to trigger early DL synchronization, early UL synchronization, or / and CSC or TCI state activation / deactivation.

[0093] Based on the L3 measurements, the CU may send a request to the target DUs for the preparation of the target cells. The request may include an indication that LTM switching will be triggered based on L3 measurements. Based on lower layer configuration received fromsource and target DU, the CU may prepare the RRC Configuration and provides it to the UE. The RRC Configuration may contain L3 measurement and reporting configurations prepared for LTM. Receiving measurements from UE (configured by the CU), the CU may decide to trigger early DL, early UL, or / and CSC based on the measurement and inform the serving DU about the action it can take. The actions may be at least one or more of TCI state or SSB index and LTM candidate ID for early downlink synchronization, SSB index and LTM candidate cell ID for early UL synchronization, or TCI state / SSB index and LTM candidate ID along with SSB index (optional for CFRA RACH based LTM) needed for the DU to include in the LTM cell switch command. Receiving measurements from UE (configured by the CU), the CU may forward the L3 measurements to serving DU. Receiving measurements from the UE (configured by the CU), the CU may decide to trigger early DL, early UL, or / and CSC based on the measurement, inform serving DU about the action it can take, and forwards the L3 measurements to serving DU. Receiving the RRC Configuration from the CU, the UE may store the configuration of LTM candidate target cell(s) and transmit a RRCReconfigurationComplete message to the CU. The UE may measure the candidate cells according to the configuration received from CU and forward the measurement reports to the CU through the serving DU. An example method may comprise receiving from the CU an indication to trigger at least one or more of the actions such as, for example, to trigger:• early TA acquisition, or• early TCI state activation / deactivation, or• LTM cell switch, and the serving DU triggers the corresponding action. An example method may comprise receiving from the CU L3 measurements, and the serving DU selects appropriate configuration, candidate cell and associated candidate TCI state(s) for early DL synchronization, candidate cell and SSB index for early UL synchronization, or / and candidate cell, TCI state, SSB index for cell switch command.

[0094] As noted with Example 2 above, an example method may comprise a CU providing LTM-Assistance-information including action and candidate target cell, wherein the LTM- Assistance-information includes TCI states, wherein the action received from the CU is totrigger at least one or more of early TA acquisition, early TCI state activation / deactivation, or LTM cell switch, and based on receiving from the CU the LTM-Assistance-information, the serving DU triggering the corresponding action(s).

[0095] The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0096] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(iii) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.”

[0097] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0098] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Claims

34CLAIMSWhat is claimed is:

1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

2. The apparatus as claimed in claim 1 where the information comprises the at least one L3 measurement.

3. The apparatus as claimed in any one of claims 1-2 where the information comprises an indication for the at least one device to trigger a user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch.

4. The apparatus as claimed in claim 3 where the indication comprises one of: a single bit flag, or a multi-bit flag.

355. The apparatus as claimed in any one of claims 3-4 where the indication for the at least one device to trigger the early downlink synchronization is for a transmission configuration indication state activation or deactivation.

6. The apparatus as claimed in any one of claims 3-4 where the indication for the at least one device to trigger the early uplink synchronization comprises an indication for a physical downlink control channel order for triggering an early random access channel for the user equipment.

7. The apparatus as claimed in any one of claims 3-4 where the indication for the at least one device to trigger the cell switch is for a cell switch command.

8. The apparatus as claimed in any one of claims 3-6 where the information comprises an indication for the at least one device to trigger the user equipment to perform at least one of the early downlink synchronization or the early uplink synchronization.

9. The apparatus as claimed in any one of claims 1-8 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving an uplink radio resource control transfer message, where the uplink radio resource control message transfer message comprises an L3 measurement report.

10. The apparatus as claimed in claim 9 where the instructions, when executed with the at least one processor, cause the apparatus to perform: sending, based at least partially on the received uplink radio resource control transfer message, lower layer triggered mobility handover information.

11. The apparatus as claimed in claim 10 where the lower layer triggered mobility handover information comprises at least one of: an indication for triggering an early TA acquisition, an indication for triggering an early transmission configuration indication activation or deactivation, oran indication for triggering a cell switch.

12. The apparatus as claimed in claim 1 where the at least one device comprises a target distributed unit, and where the sending of the information comprises sending a user equipment context setup request indicating that the lower layer triggered mobility is to be based on a L3 measurement.

13. The apparatus as claimed in claim 12 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving, based at least partially on the sent user equipment context setup request, a user equipment context setup response with a lower layer triggered mobility L3 measurement configuration.

14. The apparatus as claimed in claim 13 where the instructions, when executed with the at least one processor, cause the apparatus to perform: sending, based at least partially on the received user equipment context setup response, a user equipment context modification request for a source distributed unit, where the user equipment context modification request comprises an indication that the lower layer triggered mobility is to be based on a L3 measurement.

15. The apparatus as claimed in claim 14 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving, based at least partially on the sent user equipment context modification request, a user equipment context modification response.

16. The apparatus as claimed in any one of claims 1-15 where the instructions, when executed with the at least one processor, cause the apparatus to perform: sending a radio resource control reconfiguration message for the user equipment, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration.

17. The apparatus as claimed in any one of claims 1-15 where the instructions, when executed with the at least one processor, cause the apparatus to perform: sending a radio resource control reconfiguration message for a source distributed unit, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration.

18. The apparatus as claimed in any one of claims 1-17 where the instructions, when executed with the at least one processor, cause the apparatus to perform: sending the at least one L3 measurement of the user equipment received by the apparatus to a source distribution unit.

19. The apparatus as claimed in claim 1 where the information comprises lower layer triggered mobility information which does not include the at least one L3 measurement.

20. The apparatus as claimed in claim 19 where the lower layer triggered mobility information comprises at least one of: an indication of at least one possible action to be performed by the at least one device, or determination information for the at least one device to determine the at least one possible action to be performed by the at least one device.

21. The apparatus as claimed in claim 20 where the at least one possible action comprises at least one of: one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command.3822. The apparatus as claimed in claim 21 where, for the early downlink synchronization, the lower layer triggered mobility information comprises a synchronization signal block index and a candidate cell ID.

23. The apparatus as claimed in claim 19 where the lower layer triggered mobility information comprises an indication for the at least one device to trigger a user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch.

24. The apparatus as claimed in claim 23 where the instructions, when executed with the at least one processor, cause the apparatus to perform: for when the indication for the at least one device to trigger the user equipment to perform the early downlink synchronization, the indication comprises at least one transmission configuration indication state, and for when the indication for the at least one device to trigger the user equipment to perform the early uplink synchronization, the indication comprises at least one synchronization signal block indices and at least one candidate cell ID.

25. The apparatus as claimed in any one of claims 19-24 where the lower layer triggered mobility information comprises at least one of: more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells.

26. The apparatus as claimed in claim 19 where the lower layer triggered mobility information comprises a plurality of options to be performed by the at least one device and a priority order for determining use of the options.3927. The apparatus as claimed in any one of claims 19-26 where the lower layer triggered mobility information comprises an instruction for the at least one device to select one or more parameters for determining triggering of at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or a cell switch.

28. A method comprising: determining, by an apparatus, to prepare at least one device for lower layer triggered mobility; and sending information from an apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus29. The method of claim 28 where the information comprises the at least one L3 measurement.

30. The method as claimed in any one of claims 28-29 where the information comprises an indication for the at least one device to trigger the user equipment to perform at least one of: an early downlink synchronization, an early uplink synchronization, or a cell switch.

31. The method as claimed in claim 30 where the indication comprises one of: a single bit flag, or a multi-bit flag.4032. The method as claimed in any one of claims 30-31 where the indication for the at least one device to trigger the early downlink synchronization is for a transmission configuration indication state activation or deactivation.

33. The method as claimed in any one of claims 30-31 where the indication for the at least one device to trigger the early uplink synchronization comprises an indication for a physical downlink control channel order for triggering an early random access channel for the user equipment.

34. The method as claimed in any one of claims 30-31 where the indication for the at least one device to trigger the cell switch is for a cell switch command.

35. The method as claimed in any one of claims 30-34 where the information comprises an indication for the at least one device to trigger the user equipment to perform at least one of the early downlink synchronization or the early uplink synchronization.

36. The method as claimed in any one of claims 28-35 further comprising: receiving an uplink radio resource control transfer message, where the uplink radio resource control message transfer message comprises an L3 measurement report.

37. The method as claimed in claim 36 further comprising: sending, based at least partially on the received uplink radio resource control transfer message, lower layer triggered mobility handover information.

38. The method as claimed in claim 37 where the lower layer triggered mobility handover information comprises at least one of: an indication for triggering an early TA acquisition, an indication for triggering an early transmission configuration indication activation or deactivation, or an indication for triggering a cell switch.4139. The method as claimed in claim 28 where the at least one device comprises a target distributed unit, and where the sending of the information comprises sending a user equipment context setup request indicating that the lower layer triggered mobility is to be based on a L3 measurement.

40. The method as claimed in claim 39 further comprising: receiving, based at least partially on the sent user equipment context setup request, a user equipment context setup response with a lower layer triggered mobility L3 measurement configuration.

41. The method as claimed in claim 40 further comprising: sending, based at least partially on the received user equipment context setup response, a user equipment context modification request for a source distributed unit, where the user equipment context modification request comprises an indication that the lower layer triggered mobility is to be based on a L3 measurement.

42. The method as claimed in claim 41 further comprising: receiving, based at least partially on the sent user equipment context modification request, a user equipment context modification response.

43. The method as claimed in any one of claims 28-42 further comprising: sending a radio resource control reconfiguration message for the user equipment, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration.

44. The method as claimed in any one of claims 28-42 further comprising: sending a radio resource control reconfiguration message for a source distributed unit, where the radio resource control reconfiguration message comprises a lower layer triggered mobility L3 measurement configuration.

45. The method as claimed in any one of claims 28-44 further comprising:42 sending the at least one L3 measurement of the user equipment received by the apparatus to a source distribution unit.

46. The method as claimed in claim 28 where the information comprises lower layer triggered mobility information which does not include the at least one L3 measurement.

47. The method as claimed in claim 46 where the lower layer triggered mobility information comprises at least one of: an indication of at least one possible action to be performed by the at least one device, or determination information for the at least one device to determine the at least one possible action to be performed by the at least one device.

48. The method as claimed in claim 47 where the at least one possible action comprises at least one of: one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command.

49. The method as claimed in claim 48 where, for the early downlink synchronization, the lower layer triggered mobility information comprises a synchronization signal block index and a candidate cell ID.

50. The method as claimed in claim 46 where the lower layer triggered mobility information comprises an indication for the at least one device to trigger a user equipment to perform at least one of: an early downlink synchronization,43 an early uplink synchronization, or a cell switch.

51. The method as claimed in claim 50 further comprising: for when the indication for the at least one device to trigger the user equipment to perform the early downlink synchronization, the indication comprises at least one transmission configuration indication state, and for when the indication for the at least one device to trigger the user equipment to perform the early uplink synchronization, the indication comprises at least one synchronization signal block indices and at least one candidate cell ID.

52. The method as claimed in any one of claims 28-51 where the lower layer triggered mobility information comprises at least one of: more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells.

53. The method as claimed in claim 46 where the lower layer triggered mobility information comprises a plurality of options to be performed by the at least one device and a priority order for determining use of the options.

54. The method as claimed in any one of claims 46-53 where the lower layer triggered mobility information comprises an instruction for the at least one device to select one or more parameters for determining triggering of at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or a cell switch.

55. An apparatus comprising:44 means for determining to prepare at least one device for lower layer triggered mobility; and means for sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

56. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: determining to prepare at least one device for lower layer triggered mobility; and sending information from the apparatus based on the determination to prepare the at least one device for an early synchronization procedure and / or a cell switch for the lower layer triggered mobility, where the information is based, at least partially, on at least one L3 measurement of a user equipment received by the apparatus.

57. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

58. The apparatus as claimed in claim 57 where the receiving of the radio resource control reconfiguration message comprising the triggered mobility L3 measurement configuration is from a centralized unit, and the sending of the radio resource control measurement report is for a source distributed unit.4559. A method comprising: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

60. An apparatus comprising: means for receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and means for sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

61. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a radio resource control reconfiguration message comprising a triggered mobility L3 measurement configuration; and sending a radio resource control measurement report based, at least partially, on the triggered mobility L3 measurement configuration and an L3 measurement.

62. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of:46 an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

63. The apparatus as claimed in claim 62 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving a user equipment context modification request, where the user equipment context modification request comprises an indication that a lower layer triggered mobility is to be based on at least one L3 measurement.

64. The apparatus as claimed in claim 63 where the instructions, when executed with the at least one processor, cause the apparatus to perform: sending, based at least partially on the received user equipment context modification request, a user equipment context modification response for a centralized unit.

65. The apparatus as claimed in claim 64 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving, based at least partially on the sending of the user equipment context modification response, a radio resource control reconfiguration message.

66. The apparatus as claimed in claim 65 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving a radio resource control reconfiguration complete message from a user equipment, where the radio resource control reconfiguration complete message is based on the radio resource control reconfiguration message.

67. The apparatus as claimed in any one of claims 62-66 where the instructions, when executed with the at least one processor, cause the apparatus to perform: receiving a radio resource control measurement report from a user equipment; and47 sending, based at least partially on the received radio resource control measurement report, an uplink radio resource control transfer message for a centralized unit, where the uplink radio resource control transfer message comprises the received radio resource control measurement report, and where the received radio resource control measurement report comprises L3 measurement information measured by the user equipment.

68. The apparatus as claimed in any one of claims 62-67 where the determining to trigger is based, at least partially, on at least one of: an indication, received by the apparatus, of at least one possible action to be performed, or determination information, received by the apparatus, to determine the at least one possible action to be performed.

69. The apparatus as claimed in claim 68 where the at least one possible action comprises at least one of: one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization procedure, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization procedure, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command.

70. The apparatus as claimed in claim 69 where, for the early downlink synchronization, the lower layer triggered mobility information comprises a synchronization signal block index and a candidate cell ID.

71. The apparatus as claimed in any one of claims 62-70 where the lower layer triggered mobility information comprises at least one of: more than one candidate synchronization signal block indices, or48 more than one transmission configuration indication indices associated with one or more candidate cells.

72. The apparatus as claimed in claim 62 where the lower layer triggered mobility information comprises a plurality of options to be performed by the apparatus and a priority order for determining use of the options.

73. The apparatus as claimed in any one of claims 62-72 where the lower layer triggered mobility information comprises an instruction for the apparatus to select one or more parameters for determining triggering of at least one of the early downlink synchronization procedure, the early uplink synchronization procedure, or the cell switch.

74. A method comprising: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

75. The method as claimed in claim 74 further comprising: receiving a user equipment context modification request, where the user equipment context modification request comprises an indication that a lower layer triggered mobility is to be based on at least one L3 measurement.

76. The method as claimed in claim 75 further comprising:49 sending, based at least partially on the received user equipment context modification request, a user equipment context modification response for a centralized unit.

77. The method as claimed in claim 76 further comprising: receiving, based at least partially on the sending of the user equipment context modification response, a radio resource control reconfiguration message.

78. The method as claimed in claim 77 further comprising: receiving a radio resource control reconfiguration complete message from a user equipment, where the radio resource control reconfiguration complete message is based on the radio resource control reconfiguration message.

79. The method as claimed in any one of claims 74-78 further comprising: receiving a radio resource control measurement report from a user equipment; and sending, based at least partially on the received radio resource control measurement report, an uplink radio resource control transfer message for a centralized unit, where the uplink radio resource control transfer message comprises the received radio resource control measurement report, and where the received radio resource control measurement report comprises L3 measurement information measured by the user equipment.

80. The method as claimed in any one of claims 74-79 where the determining to trigger is based, at least partially, on at least one of: an indication, received by the apparatus, of at least one possible action to be performed, or determination information, received by the apparatus, to determine the at least one possible action to be performed.

81. The method as claimed in claim 80 where the at least one possible action comprises at least one of:50 one or more candidate transmission configuration indication states and candidate cell ID for an early downlink synchronization procedure, one or more synchronization signal block indices and candidate cell ID for an early uplink synchronization procedure, or a candidate transmission configuration indication state and candidate cell ID with a synchronization signal block index for a cell switch command.

82. The method as claimed in claim 81 where, for the early downlink synchronization, the lower layer triggered mobility information comprises a synchronization signal block index and a candidate cell ID.

83. The method as claimed in any one of claims 74-82 where the lower layer triggered mobility information comprises at least one of more than one candidate synchronization signal block indices, or more than one transmission configuration indication indices associated with one or more candidate cells.

84. The method as claimed in claim 74 where the lower layer triggered mobility information comprises a plurality of options to be performed by the apparatus and a priority order for determining use of the options.

85. The method as claimed in any one of claims 74-84 where the lower layer triggered mobility information comprises an instruction for the apparatus to select one or more parameters for determining triggering of at least one of the early downlink synchronization procedure, the early uplink synchronization procedure, or the cell switch.

86. An apparatus comprising:51 means for receiving lower layer triggered mobility information from a centralized unit; and means for determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

87. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving lower layer triggered mobility information from a centralized unit; and determining, based at least partially on the received lower layer triggered mobility information, to trigger for a user equipment at least one of: an early downlink synchronization procedure, an early uplink synchronization procedure, or cell switch command.

88. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.5289. A method comprising: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

90. An apparatus comprising: means for receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and means for, based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

91. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving a request for a triggered mobility to be based, at least partially, on an L3 measurement; and based at least partially on the received request, sending a message to a centralized unit with a triggered mobility L3 measurement configuration.

Images