WO2025075546A1

WO2025075546A1 - Timing advance for layer one triggered mobility

Info

Publication number: WO2025075546A1
Application number: PCT/SE2024/050857
Authority: WO
Inventors: Antonino ORSINO; Icaro Leonardo DA SILVA; Ioanna Pappa
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-10-06
Filing date: 2024-10-04
Publication date: 2025-04-10
Anticipated expiration: 2026-04-06

Abstract

According to some embodiments, a method is performed by a target network node. The method comprises receiving a request from a source network node for a random access configuration for performing an early timing advance (TA) acquisition procedure and transmitting the random access configuration to the source network node. The random access configuration comprises a random access preamble to be transmitted by a wireless device. The method further comprises receiving the random access preamble from the wireless device. Based on the received preamble, the method further comprises identifying the source network node associated with the early TA acquisition procedure and transmitting a TA value for the wireless device to the source network node.

Description

Timing Advance for Layer One Triggered Mobility

TECHNICAL FIELD

[0001] The present disclosure generally relates to communication networks, and more specifically to timing advance for layer one (Ll)/layer two (L2) based inter-cell mobility.

BACKGROUND

[0002] Third Generation Partnership Project (3 GPP) Release 18 includes a work item referred to as further New Radio (NR) mobility enhancements. The work item includes a technical area entitled layer one (Ll)/layer two (L2) based inter-cell mobility. According to the work item description (WID) RP -223520, “Further NR mobility enhancements,” 3GPP TSG RAN Meeting #98-e, December 12-16, 2022, when a user equipment (UE) moves from the coverage area of one cell to another cell, at some point a serving cell change needs to be performed. Currently serving cell change is triggered by layer three (L3) measurements and is done by Radio Resource Control (RRC) signaling triggered Reconfiguration with Synchronization for change of PCell and PSCell, as well as release add for SCells when applicable. All cases involve complete L2 (and LI) resets, leading to longer latency, larger overhead and longer interruption time than beam switch mobility. The goal of L1/L2 based inter-cell mobility is to enable a serving cell change via L1/L2 signaling to reduce the latency, overhead and interruption time.

[0003] The work item objectives include specifying mechanism and procedures of L1/L2 based inter-cell mobility for mobility latency reduction, such as: configuration and maintenance for multiple candidate cells to allow fast application of configurations for candidate cells; dynamic switch mechanism among candidate serving cells (including SpCell and SCell) for the potential applicable scenarios based on L1/L2 signaling; LI enhancements for inter-cell beam management, including LI measurement and reporting, and beam indication; timing advance management; and central unit (CU)-distributed unit (DU) interface signaling to support L1/L2 mobility.

[0004] The procedures of L1/L2 based inter-cell mobility are applicable to the following scenarios: standalone, carrier aggregation (CA) and NR dual connectivity (DC) case with serving cell change within one cell group (CG); intra-DU case and intra-CU inter-DU case (applicable for standalone and CA: no new RAN interfaces are expected); both intra-frequency and interfrequency; both frequency range one (FR1) and frequency range two (FR2); and source and target cells may be synchronized or non-synchronized. [0005] L1/L2 based inter-cell mobility may also be referred to as LTM, L1/L2 -triggered mobility or lower layer-triggered mobility. A basic principle with L1/L2 -triggered mobility is that the UE is pre-configured, by the network, with an RRC configuration per LTM candidate cell, sometimes also known as a LTM candidate cell configuration. Such a LTM candidate cell configuration may be an RRCReconfiguration message or one or more information elements (IEs)/fields/ parameters, such as CellGroupConfig. The UE performs measurements on the LTM candidate cells and transmits corresponding measurement reports to the network. The network then triggers the execution of a LTM cell switch procedure in the UE to one of the LTM candidate cells by transmitting lower layer signaling in a medium access control (MAC) control element (CE), sometimes also referred to as a LTM cell switch command, to the UE, which then connects to the particular LTM candidate cell and switches to the LTM candidate cell configuration.

[0006] A further aspect that has been agreed in the context of LTM is early uplink synchronization. This is when the UE is configured by the network with an early uplink synchronization configuration with, e.g., a random access channel (RACH) configuration.

[0007] When configured by the network, it is possible for a UE in RRC CONNECTED to be uplink synchronized with a cell that is different from the current serving cell.

[0008] Figure l is a flow diagram illustrating the early timing advance (TA) acquisition (early uplink synchronization) procedure triggered by the network. At step 1, the gNB to which Cell A belongs provides the TA acquisition configuration to the UE within the RRCReconfiguration message. The TA acquisition configuration includes RRC configuration information required to send a random access preamble to Cell B so that the gNB to which Cell B belongs can calculate a TA value to be used by the UE, e.g., if an LTM cell switch procedure is executed to Cell B. The TA acquisition configuration may include information for one or multiple cells to which the TA acquisition procedure may be executed by the UE.

[0009] At step 2, the UE replies with the RRCReconfigurationComplete message.

[0010] At step 3, the gNB to which Cell A belongs sends a physical downlink control channel (PDCCH) order message to the UE to initiate a TA acquisition procedure with Cell B. The PDCCH order includes the information required to send a random access preamble to Cell B.

[0011] At step 4, the UE sends a random access preamble to Cell B so that the gNB to which Cell B belongs can calculate a TA value to be used by the UE, e.g., if an LTM cell switch procedure is triggered to Cell B. The gNB to which Cell A belongs may indicate the retransmission of preamble for TA acquisition if no TA is obtained.

[0012] At step 5, the gNB to which Cell A belongs provides the TA value calculated by the gNB to which Cell B belongs during the TA acquisition procedure, e.g. in LTM cell switch command MAC CE which initiate cell switch procedure to Cell B if an LTM cell switch procedure is triggered to Cell B.

[0013] There currently exist certain challenges. For example, according to what has been agreed so far in 3 GPP, a UE is configured by the network with a RACH configuration that is used by the UE to perform the early uplink synchronization procedure. This means that the network can send signaling to the UE (i.e., a PDCCH order) so that the UE initiates the random access procedure towards one (indicated within the PDCCH order) of the configured LTM candidate cells, i.e. the UE selects a synchronization signal block (SSB) of the LTM candidate cell indicated in the PDCCH order, selects a PRACH resource based on the selected SSB, and transmits a preamble to the selected PRACH resource. The network node of the LTM candidate cell (e.g., a Candidate DU), when receiving the random access preamble from the UE, calculates a TA value, which needs to be sent to the source node (the current serving cell of the UE), e.g., the S-DU, so that the source node can include the TA value within the LTM cell switch command that is to be transmitted to the UE when an LTM cell switch procedure needs to be executed.

[0014] Nevertheless, 3GPP has not discussed how the source node (e.g., S-DU) is identified by the candidate DU, LTM candidate cell (or the CU) after the TA value has been calculated, so that the calculated TA value is sent to the correct S-DU. If the source node (e.g., S-DU) cannot be determined, this means that the TA value cannot be included within the LTM cell switch command that is sent to the UE to execute an LTM cell switch procedure and/or the TA value is sent to the wrong S-DU. Therefore, the UE will always need to perform the random access procedure when executing an LTM cell switch procedure with a consequent longer connectivity interruption.

SUMMARY

[0015] As described above, certain challenges currently exist with layer one (Ll)/layer two (L2) based inter-cell mobility. Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, particular embodiments include solutions in a network node, such as a central unit (CU) and/or a candidate distributed unit (DU), to identify to which source node (e.g., which source DU (S-DU)) a timing advance (TA) value should be sent, wherein the TA value has been calculated by the candidate DU (associated to an L1/L2 triggered mobility (LTM) candidate cell) that has received a random access preamble from the user equipment (UE). In other words, the network node (C-DU or the CU) identifies which S- DU has triggered the UE to transmit a random access (RA) preamble based on which a TA value is calculated, so that the TA value is sent by the CU and/or the C-DU to the S-DU that triggered the preamble transmission. [0016] Particular embodiments include methods for a source network node, such as a source gNB or a source DU (e.g., S-DU), to provide a TA value to the UE within a LTM cell switch command that is sent to trigger the execution of an LTM cell switch procedure. In the embodiments, when the source network node (e.g., S-DU) determines that a TA acquisition procedure needs to be triggered at the UE, after sending a physical downlink control channel (PDCCH) order to the UE including a preamble index and synchronization signal block (SSB) index, the source network node (S-DU) sends an indication to a target network node (e.g., candidate DU) or a third network node (e.g., a CU) to inform about the preamble index and SSB index selected for the UE, i.e., to inform which preamble the UE is transmitting to the target network node (e.g., to the C-DU). In this way, the target network node or the CU knows to which source network node the TA value should be sent. The TA value the S-DU transmits to the UE is associated to the S-DU by the fact that the S-DU has indicated to the target network node (e.g., C- DU) and/or the third node (e.g., the CU) one or more physical random access channel (PRACH) related configurations (e.g., indication of a preamble, such as a preamble index and/or selected SSB of the LTM candidate cell) the S-DU has provided the UE during the triggering of the TA establishment, so that the third network node and/or the target network node are aware that when the indicated preamble is received (in the PRACH resources associated to the indicated beam/SSB) at the target network node and/or at the third network node it is known to be associated to the S- DU that has indicated the PRACH configuration.

[0017] Particular embodiments include methods for a target network node, such as a target gNB or a target DU (e.g. a Candidate DU for LTM), to provide a TA value to a source network node (or to be forwarded to the source network node by a third node) so that the TA value may be sent to the UE within a LTM cell switch command that is sent to trigger the execution of an LTM cell switch procedure. In the embodiments, the target network node (e.g., the C-DU for which LTM is being configured) allocates a first RA configuration (e.g., a PRACH configuration for early uplink synchronization, such as one or more preamble(s) and/or PRACH time/frequency resource(s), which may be a dedicated configuration) to one or more UEs being served by a certain source network node (e.g., one or more UEs in an S-DU). Thus, the first RA configuration gets associated to the first S-DU in the C-DU, so that when a preamble in the first RA configuration is received in an LTM candidate cell of the C-DU, according to the first RA configuration (e.g., in the PRACH resources associated to the first RA configuration), the C-DU knows that the received preamble is associated to the first S-DU, so that the C-DU calculates the TA value and associated to the first S-DU. [0018] Further, the target network node (C-DU) may also receive from the CU an identifier of a source network node and the target network node may link a certain random access configuration for performing an early TA acquisition to be used for the early TA acquisition with the identifier of the source network node. According to this, when a random access preamble is received from the UE, the target network node is able to link the preamble to a random access configuration used for performing an early TA acquisition and, in turn, to a source network node to where the TA value should be sent.

[0019] Particular embodiments include methods for a third network node, such as a central unit (CU), to provide a TA value to a source network node so that the TA value may be sent to the UE within a LTM cell switch command that is sent to trigger the execution of an LTM cell switch procedure. In the embodiments, the third network node may provide a target network node with a source network node identifier, and after that receiving a TA value to be sent to source network node for which an identifier was sent. Further, the third network node may also receive from a source network node a preamble index and an SSB index after that the source network node decided to trigger an early TA acquisition procedure at the UE.

[0020] According to some embodiments, a method is performed by a target network node. The method comprises receiving a request from a source network node for a random access configuration for performing an early TA acquisition procedure and transmitting the random access configuration to the source network node. The random access configuration comprises a random access preamble to be transmitted by a wireless device. The method further comprises receiving the random access preamble from the wireless device. Based on the received preamble, the method further comprises identifying the source network node associated with the early TA acquisition procedure and transmitting a TA value for the wireless device to the source network node.

[0021] In particular embodiments, the method further comprises storing an association between the random access configuration and the source network node.

[0022] In particular embodiments, the association between the random access configuration and the source network node is based on the random access preamble.

[0023] In particular embodiments, the method further comprises receiving an uplink channel from the wireless device based on the TA value.

[0024] In particular embodiments, the random access configuration applies to all wireless devices served by the source network node, or a subset of wireless devices served by the source network node. [0025] According to some embodiments, a method is performed by a source network node. The method comprises transmitting a request to a target network node for a random access configuration for performing an early TA acquisition procedure and receiving the random access configuration from the target network node. The random access configuration comprises a random access preamble to be transmitted by a wireless device. The method further comprises transmitting an order to the wireless device to perform an early TA acquisition procedure with the target network node. The order comprises an indication of the random access preamble. The method further comprises receiving from the target network node a TA value for the wireless device.

[0026] In particular embodiments, the source network node receives the TA value from the target network node based on the random access preamble transmitted by the wireless device.

[0027] In particular embodiments, the method further comprises transmitting an order to the wireless device to perform a LTM cell switch procedure to the target network node. The order comprises the TA value.

[0028] According to some embodiments, a network node comprises processing circuitry operable to perform any of the network node methods described above.

[0029] Also disclosed is a computer program product comprising a non-transitory computer readable medium storing computer readable program code, the computer readable program code operable, when executed by processing circuitry to perform any of the methods performed by the network nodes described above.

[0030] Certain embodiments may provide one or more of the following technical advantages. For example, particular embodiments facilitate a target network node (e.g., a C-DU) or a CU to determine to which source network node (e.g., which S-DU) the TA value should be sent to, after that TA value has been calculated by the target network node, e.g., the C-DU (upon receiving a random access preamble from the UE). This enables the source network node (e.g., S-DU) to include the TA value within an LTM cell switch command and transmit that LTM cell switch command to the UE, so that the UE will not need to execute a random access procedure when performing an LTM cell switch procedure. This facilitates shorter connectivity interruption and faster LTM cell switch.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present disclosure may be best understood by way of example with reference to the following description and accompanying drawings that are used to illustrate embodiments of the present disclosure. In the drawings: Figure 1 is a flow diagram illustrating early timing advance (TA) acquisition (early uplink synchronization)] procedure triggered by the network;

Figure 2 illustrates an LTM procedure for a UE between a S-DU and a C-DU, according to particular embodiments;

Figure 3 shows an example of a communication system, according to certain embodiments;

Figure 4 shows a user equipment (UE), according to certain embodiments;

Figure 5 shows a network node, according to certain embodiments;

Figure 6 is a block diagram of a host, according to certain embodiments;

Figure 7 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized;

Figure 8 shows a communication diagram of a host communicating via a network node with a UE over a partially wireless connection in accordance with some embodiments;

Figure 9 is a flowchart illustrating an example method in a target network node, according to certain embodiments; and

Figure 10 is a flowchart illustrating an example method in a source network node, according to certain embodiments.

DETAILED DESCRIPTION

[0032] As described above, certain challenges currently exist with layer one (Ll)/layer two (L2) based inter-cell mobility. Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, particular embodiments include solutions in a network node, such as a central unit (CU) and/or a candidate distributed unit (DU), to identify to which source node (e.g., which source DU (S-DU)) a timing advance (TA) value should be sent, wherein the TA value has been calculated by the candidate DU (associated to an L1/L2 triggered mobility (LTM) candidate cell) that has received a random access preamble from the user equipment (UE).

[0033] Particular embodiments are described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0034] The term “L1/L2 based inter-cell mobility” is used herein as used in the Third Generation Partnership Project (3GPP) work item description, and also interchangeably referred to as the terms L1/L2 mobility, Ll-mobility, LI based mobility, Ll/L2-centric inter-cell mobility, L1/L2 inter-cell mobility L1/L2 -triggered mobility, lower-layer triggered mobility or LTM. The basic principle is that a UE normally receives a lower layer signaling from the network indicating to the UE a change (or switch or activation) of its serving cell (e.g., change of PCell, from a source to a target PCell), wherein a lower layer signaling is a message/ signaling of a lower layer protocol, which sometimes may be referred as a L1/L2 inter-cell mobility execution command or LTM cell switch command. The change of serving cell (e.g., change of PCell) may also lead to a change in Scell(s) for the same cell group, e.g. if the command triggers the UE to change to another cell group configuration of the same type (e.g., another master cell group (MCG) configuration). Before the UE receives the LTM cell switch command, the UE is configured by the network with one or more LTM candidate cell configurations (e.g., reception of a Radio Resource Control (RRC) Reconfiguration message, with at least one LTM candidate cell configuration). A LTM candidate cell configuration may include parameters in the information element (IE) CellGroupConfig for an LTM candidate cell and/or an embedded RRC Reconfiguration for an LTM candidate cell.

[0035] The term LTM cell switch procedure refers to the process of a UE switching (or changing) its cell from a source cell to a target cell (which may be referred to as an LTM candidate cell or a neighbor cell), using L1/L2 -triggered mobility (LTM). In the context of LTM, an LTM cell switch procedure may sometimes also be referred to as L1/L2 based inter-cell mobility execution, LTM execution, dynamic switch, LTM switch, LTM cell switch, LTM serving cell change or LTM cell change. As used herein, switching to the LTM candidate cell configuration comprises the UE considering that an LTM candidate cell becomes its new special cell (SpCell), e.g. PCell for LTM being configured for an MCG and/or PSCell for LTM being configured for a secondary cell group (SCG); or, changing its SpCell from the current PCell to an LTM candidate cell.

[0036] Even if the term switch or change of cells is used, that may comprise a switch or change of a whole cell group configuration, which includes a change in the SpCell (e.g., change of PCell, or change of PSCell) and a change in SCells of the cell group (e.g., addition, modification and/or release of one or more SCells).

[0037] An LTM cell switch procedure may be triggered in the UE by reception of an LTM cell switch command, or alternatively, triggered by another event, such as a condition, e.g. a triggering condition used for conditional configuration, such as conditional handover, being fulfilled, as a result of recovery from radio link failure or handover failure.

[0038] An LTM candidate cell is a cell that a UE is configured with when configured with L1/L2 -triggered mobility. That is a cell that the UE can move to in an LTM cell switch procedure. Such cells may also be referred to as candidate cell(s), candidates, mobility candidates, nonserving cells, additional cells, target candidate cell, target candidate, etc. An LTM candidate cell is a cell the UE may perform measurements on (e.g., channel state information (CSI) measurements) so that the UE reports the measurements, and the network may make a decision on which beam (e.g., transmission configuration indicator (TCI) state) and/or cell to which the UE is to be switched. An LTM candidate cell may be a candidate to be a target PCell or PSCell, or an SCell of a cell group (e.g., MCG SCell or a SCG SCell).

[0039] Particular examples refer to at least one LTM candidate cell configuration and that the UE has received at least one LTM candidate cell configuration. This is also sometimes referred to as a configuration of an LTM candidate cell, which may be an RRC configuration, such as encapsulated in a RRC Reconfiguration message, that the UE receives when being configured with L1/L2 -triggered mobility. An LTM candidate cell configuration comprises the configuration that the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to the LTM candidate cell, e.g. upon reception of the LTM cell switch command indicating the UE to perform an LTM cell switch procedure to the LTM candidate cell, which becomes the target cell and the current (new) SpCell, or an SCell in a serving frequency.

[0040] The LTM candidate cell configuration comprises parameters of a serving cell (or multiple serving cells, such as a cell group), comprising one or more of the groups of parameters, such as an RRCReconfiguration message an IE CellGroupConfig or an IE SpCellConfig (or the IE SCellConfig, for a secondary cell). An LTM candidate cell configuration may, in one example, comprise one or more of: i) the PCell configuration and one or more SCell configuration(s) of an MCG; ii) the PSCell configuration and one or more SCell configuration(s) of a SCG. The terms LTM candidate configuration, LTM configuration, LTM candidate target cell configuration, LTM target candidate (cell) configuration may be used interchangeably when referring to LTM candidate cell configuration. An LTM candidate cell configuration is associated with an identifier that is used in the signaling when referring to a certain LTM candidate cell configuration, such as when the UE receives the LTM candidate cell configuration and when the UE receives an LTM cell switch command indicating the UE to perform an LTM cell switch procedure to the LTM candidate cell. The identifier is sometimes referred to as the LTM candidate cell configuration identity or LTM candidate configuration index (or similar).

[0041] The actual LTM candidate cell configuration and its content and/or structure of the IE and/or embedded message may be referred to as an RRC model for the candidate configuration, or simply RRC model. An LTM candidate cell configuration comprises the configuration that the UE needs to operate accordingly when the UE performs (executes) L1/L2 based inter-cell mobility to an LTM candidate cell upon reception of the lower layer signaling (MAC CE) indicating a L1/L2 based inter-cell mobility to a LTM candidate cell (which becomes the target cell and the current (new) PCell, or an SCell in a serving frequency), or upon reception of the lower layer signaling (MAC CE) indicating a L1/L2 based inter-cell mobility to an LTM candidate cell configuration indicated with a candidate configuration index (sometimes also denoted candidate configuration ID). The UE may be configured with multiple LTM candidate cell configurations, so a candidate DU generates and sends to the CU multiple configuration(s). The actual LTM candidate cell configuration the UE receives during the LTM configuration may be a delta signaling to be applied on top of a reference configuration, so that the actual configuration the UE is to use in the candidate cell upon LTM cell switch is the combination of the LTM candidate cell configuration and the reference configuration (e.g., separately signaled by the network to the UE). [0042] Particular embodiments include a method at a UE to acquire a TA value to be used when executing an LTM cell switch procedure. The method comprises: receiving from an S-DU a trigger to transmit a preamble for early uplink (UL) synchronization to an LTM candidate cell of a candidate DU (C-DU); transmitting the preamble to the LTM candidate cell of the C-DU; receiving a TA value within an LTM cell switch command from the S-DU; applying the received TA value during the execution of an LTM cell switch procedure; and using the received TA in the LTM candidate cell indicated within the LTM cell switch command after the completion of the LTM cell switch procedure. The TA value is associated to the S-DU that has triggered the UE to transmit the preamble for early uplink synchronization.

[0043] In some embodiments, the TA value is associated to the S-DU that triggered the UE to transmit the preamble for early uplink synchronization by associating the TA value to a preamble that is indicated in a random access channel (RACH) configuration associated to the S-DU.

[0044] Some embodiments include a method at a source network node, such as a source gNB or a source DU, to provide a TA value to the UE within a LTM cell switch command that is sent to trigger the execution of an LTM cell switch procedure. The method comprises: determining that an early TA acquisition procedure needs to be initiated at the UE; transmitting to the UE a signaling to initiate the early TA acquisition procedure; transmitting to a target network node or a third network node an indication about the information included to the signaling sent to the UE to initiate the early TA acquisition procedure; and receiving from a target network node or a third network node a TA value to be included within an LTM cell switch command sent to the UE to initiate an LTM cell switch procedure.

[0045] In particular embodiments, the information transmitted by the source network node to the third network node or target network node is the same as the information sent to the UE in the signaling to initiate an early TA acquisition procedure. In some embodiments, the information transmitted by the source network node to the third network node or target network node is a subset of the information sent to the UE in the signaling to initiate an early TA acquisition procedure. In some embodiments, the information transmitted by the source network node to the third network node or target network node may include one or more of the following: a preamble index ID, a source network node identifier, an SSB index, a random access configuration identifier, a UE identifier, and an LTM candidate cell identifier.

[0046] In particular embodiments, the source network node receives from a third network node or a target network node an indication with a TA value and which may include further one or more of the following: a TA value, a UE identifier, an LTM candidate cell identifier, a preamble index ID, and a random access configuration identifier.

[0047] Some embodiments include a method at a target network node, such as a target gNB or a target DU, to provide a TA value to a source network node so that the TA value may be sent to the UE within an LTM cell switch command that is sent to trigger the execution of an LTM cell switch procedure. The method comprises: receiving a request from a third network node or source network node to provide a random access configuration for the UE to perform an early TA acquisition procedure; determining a random access configuration for executing an early TA acquisition procedure that may be used by UEs belonging to the source network node; transmitting the determined random access configuration to a third network node which in turn transmits the determined random access configuration to the source network node; receiving from a source network node (eventually via a third network node) an indication that an early TA acquisition procedure has been triggered at the UE; receiving a random access preamble from a UE; determining a TA value for the UE from which the random access preamble had been received; determining a source network node to which the determined TA value should be transmitted; and transmitting the determined TA value to the determined source network node.

[0048] In particular embodiments, the target network node determines the random access configuration for the early TA acquisition procedure according to one or more of the following options. In one option, the target network node generates a random access configuration that may be used for a subset of UE that are currently served by the source network node. In one example, the target network node, when transmitting the generated random access configuration to perform an early TA acquisition, also includes the UE identifiers for which the configuration is valid (i.e., may be used). In one example, the target network node may split the available random access preambles and provide a subset of them to a subset of UEs served by the source network node. For example, Preamble IDs 1-32 may be used for UE IDs 50-100 and Preamble IDs 33-64 may be used by UE IDs 0-50. [0049] In one option, the target network node generates a random access configuration that may be used by all UEs of a source network node. In one example, the target network node may decide to split the available random access preambles so that a subset of them is used by a source network node and another subset of them is used by another source network node. For example, Preamble IDs 1-32 can be used by source network node with ID 1 and Preamble IDs 33-64 can be used by a source network node with ID 2.

[0050] In one option, the target network node generates a random access configuration that may be used by a subset of UEs of one source network node. In one example, the target network node may decide to split the available random access preambles so that a subset can be used by a subset of UEs served by a source network node, and another subset can be used by a subset of UEs served by another source network node. For example: Preamble IDs 1-16 may be used by UE IDs 1-25 of source network node ID1; Preamble IDs 17-32 may be used by UE IDs 26-50 of source network node ID1; Preamble IDs 33-48 may be used by UE IDs 1-25 of source network node ID2; and Preamble IDs 49-64 may be used by UE IDs 26-50 of source network node ID2.

[0051] In one option, the target network node generates a random access configuration that is only applicable to a source network node identifier received by a third network node when requesting to provide a random access configuration for the early TA acquisition procedure.

[0052] In particular embodiments, the target network node transmits the determined random access configuration to a third network node and the indication may include one or more of the following: one or a list of UE identifiers for which a certain random access configuration is applicable; a random access configuration identifier; and one or a list of source network node identifiers for which a certain random access configuration is applicable.

[0053] In particular embodiments, the target network node receives from a source network node or a third network node, an indication that an early TA acquisition procedure has been triggered by the source network node to the UE. The indication may include one or more of the following: a random access preamble identifier; a source network node identifier; an SSB identifier; a random access configuration identifier; and an LTM candidate cell identifier.

[0054] In particular embodiments, the target network node, after determining a TA value, determines the source network node to which the TA value should be sent according to one of more of the following.

[0055] In one example, the target network node checks the mapping between a UE identifier, a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier. [0056] In one example, the target network node checks the mapping between a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier.

[0057] In one example, the target network node checks the mapping between a UE identifier and a certain source network node identifier.

[0058] In one example, the target network node is informed by the source network node that an early TA acquisition procedure has been triggered to the UE and is informed about the information the source network node has included in the PDCCH order sent to the UE.

[0059] Some embodiments include a method at a third network node, such as a central unit (CU), to provide a TA value to a source network node so that the TA value may be sent to the UE within a LTM cell switch command that is sent to trigger the execution of an LTM cell switch procedure. The method comprises: transmitting a request to a target network node to provide a random access configuration for the UE to perform an early TA acquisition procedure; receiving a random access configuration from a target network node; transmitting the received random access configuration to the source network node; receiving from the source network node an indication that an early TA acquisition procedure has been triggered at the UE; receiving a TA value from a target network node; determining a source network node to which the determined TA value should be transmitted; and transmitting the determined TA value to the determined source network node.

[0060] In particular embodiments, the third network node, when transmitting the request to provide a random access configuration for an early TA acquisition procedure, further sends in the request a source network node identifier. The CU may use the source network node identifier to link the random access configuration received from the target network node. Therefore, when a TA value is received from the particular target network node, the third network node knows that the TA value should be sent to the linked source network node.

[0061] In particular embodiments, the third network node receives from a target network node a random access configuration for an early TA acquisition procedure and together with the configuration the third network node may further receive one or more of the following information (linked to the received random access configuration): one or a list of UE identifiers for which a certain random access configuration is applicable; a random access configuration identifier; and one or a list of source network node identifiers for which a certain random access configuration is applicable.

[0062] In particular embodiments, the third network node receives from a source network node an indication that an early TA acquisition procedure has been triggered by the source network node to the UE. The indication may include one or more of the following: a random access preamble identifier, a source network node identifier, a SSB identifier, a random access configuration identifier, and a LTM candidate cell identifier.

[0063] In particular embodiments, the third network node, after receiving the TA value from the target network node determines the source network node to which the TA value should be sent according to one of more of the following.

[0064] In one example, the third network node checks the mapping between a target network node, a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier. The third network node may determine that a random access configuration with a certain identifier is linked to a certain target network node and to a certain source network node.

[0065] In one example, the third network node checks the mapping between a target network node, a random access configuration identifier (or the identifier of a field which is part of the random access configuration), a source network node identifier, and a UE identifier.

[0066] In one example, the third network node checks the mapping between a UE identifier and a source network node identifier.

[0067] In one example, the third network node is informed by the source network node that an early TA acquisition procedure has been triggered to the UE and is informed about the information the source network node has included in the PDCCH order sent to the UE.

[0068] Figure 2 is a flow diagram illustrating the example embodiments described above. Figure 2 illustrates an LTM procedure for a UE between a S-DU and a C-DU, according to particular embodiments.

[0069] Figure 3 shows an example of a communication system 100 in accordance with some embodiments. In the example, the communication system 100 includes a telecommunication network 102 that includes an access network 104, such as a radio access network (RAN), and a core network 106, which includes one or more core network nodes 108. The access network 104 includes one or more access network nodes, such as network nodes 110a and 110b (one or more of which may be generally referred to as network nodes 110), or any other similar 3^rd Generation Partnership Project (3 GPP) access node or non-3GPP access point. The network nodes 110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 112a, 112b, 112c, and 112d (one or more of which may be generally referred to as UEs 112) to the core network 106 over one or more wireless connections.

[0070] Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 100 may include any number of wired or wireless networks, network nodes, UEs, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. The communication system 100 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

[0071] The UEs 112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes 110 and other communication devices. Similarly, the network nodes 110 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs 112 and/or with other network nodes or equipment in the telecommunication network 102 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network 102.

[0072] In the depicted example, the core network 106 connects the network nodes 110 to one or more hosts, such as host 116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 106 includes one more core network nodes (e.g., core network node 108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and/or a User Plane Function (UPF).

[0073] The host 116 may be under the ownership or control of a service provider other than an operator or provider of the access network 104 and/or the telecommunication network 102 and may be operated by the service provider or on behalf of the service provider. The host 116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio/video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server. [0074] As a whole, the communication system 100 of Figure 3 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0075] In some examples, the telecommunication network 102 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunications network 102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 102. For example, the telecommunications network 102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and/or Massive Machine Type Communication (mMTC)/Massive loT services to yet further UEs.

[0076] In some examples, the UEs 112 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 104. Additionally, a UE may be configured for operating in single- or multi -RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0077] In the example, the hub 114 communicates with the access network 104 to facilitate indirect communication between one or more UEs (e.g., UE 112c and/or 112d) and network nodes (e.g., network node 110b). In some examples, the hub 114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 114 may be a broadband router enabling access to the core network 106 for the UEs. As another example, the hub 114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 110, or by executable code, script, process, or other instructions in the hub 114. As another example, the hub 114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 114 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub 114 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices.

[0078] The hub 114 may have a constant/persistent or intermittent connection to the network node 110b. The hub 114 may also allow for a different communication scheme and/or schedule between the hub 114 and UEs (e.g., UE 112c and/or 112d), and between the hub 114 and the core network 106. In other examples, the hub 114 is connected to the core network 106 and/or one or more UEs via a wired connection. Moreover, the hub 114 may be configured to connect to an M2M service provider over the access network 104 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 110 while still connected via the hub 114 via a wired or wireless connection. In some embodiments, the hub 114 may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node 110b. In other embodiments, the hub 114 may be a nondedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 110b, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

[0079] Figure 4 shows a UE 200 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle-mounted or vehicle embedded/integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3 GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and/or an enhanced MTC (eMTC) UE. [0080] A UE may support device-to-device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to- everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and/or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0081] The UE 200 includes processing circuitry 202 that is operatively coupled via a bus 204 to an input/output interface 206, a power source 208, a memory 210, a communication interface 212, and/or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 2. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0082] The processing circuitry 202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 210. The processing circuitry 202 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field- programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 202 may include multiple central processing units (CPUs).

[0083] In the example, the input/output interface 206 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and/or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0084] In some embodiments, the power source 208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 208 may further include power circuitry for delivering power from the power source 208 itself, and/or an external power source, to the various parts of the UE 200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 208 to make the power suitable for the respective components of the UE 200 to which power is supplied.

[0085] The memory 210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 210 includes one or more application programs 214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 216. The memory 210 may store, for use by the UE 200, any of a variety of various operating systems or combinations of operating systems.

[0086] The memory 210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and/or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 210 may allow the UE 200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 210, which may be or comprise a device-readable storage medium. [0087] The processing circuitry 202 may be configured to communicate with an access network or other network using the communication interface 212. The communication interface 212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 222. The communication interface 212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 218 and/or a receiver 220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 218 and receiver 220 may be coupled to one or more antennas (e.g., antenna 222) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0088] In the illustrated embodiment, communication functions of the communication interface 212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and/or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol/intemet protocol (TCP/IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0089] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient). [0090] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0091] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door/window sensor, a flood/moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or itemtracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and/or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 200 shown in Figure 2.

[0092] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and/or measurements and transmits the results of such monitoring and/or measurements to another UE and/or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3 GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

[0093] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and/or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators. [0094] Figure 5 shows a network node 300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and/or operable to communicate directly or indirectly with a UE and/or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NRNodeBs (gNBs)).

[0095] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units and/or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0096] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell/multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and/or Minimization of Drive Tests (MDTs).

[0097] The network node 300 includes a processing circuitry 302, a memory 304, a communication interface 306, and a power source 308. The network node 300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 304 for different RATs) and some components may be reused (e.g., a same antenna 310 may be shared by different RATs). The network node 300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 300.

[0098] The processing circuitry 302 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node 300 components, such as the memory 304, to provide network node 300 functionality.

[0099] In some embodiments, the processing circuitry 302 includes a system on a chip (SOC). In some embodiments, the processing circuitry 302 includes one or more of radio frequency (RF) transceiver circuitry 312 and baseband processing circuitry 314. In some embodiments, the radio frequency (RF) transceiver circuitry 312 and the baseband processing circuitry 314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 312 and baseband processing circuitry 314 may be on the same chip or set of chips, boards, or units.

[0100] The memory 304 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device-readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by the processing circuitry 302. The memory 304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and/or other instructions capable of being executed by the processing circuitry 302 and utilized by the network node 300. The memory 304 may be used to store any calculations made by the processing circuitry 302 and/or any data received via the communication interface 306. In some embodiments, the processing circuitry 302 and memory 304 is integrated.

[0101] The communication interface 306 is used in wired or wireless communication of signaling and/or data between a network node, access network, and/or UE. As illustrated, the communication interface 306 comprises port(s)/terminal(s) 316 to send and receive data, for example to and from a network over a wired connection. The communication interface 306 also includes radio front-end circuitry 318 that may be coupled to, or in certain embodiments a part of, the antenna 310. Radio front-end circuitry 318 comprises filters 320 and amplifiers 322. The radio front-end circuitry 318 may be connected to an antenna 310 and processing circuitry 302. The radio front-end circuitry may be configured to condition signals communicated between antenna 310 and processing circuitry 302. The radio front-end circuitry 318 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 320 and/or amplifiers 322. The radio signal may then be transmitted via the antenna 310. Similarly, when receiving data, the antenna 310 may collect radio signals which are then converted into digital data by the radio front-end circuitry 318. The digital data may be passed to the processing circuitry 302. In other embodiments, the communication interface may comprise different components and/or different combinations of components.

[0102] In certain alternative embodiments, the network node 300 does not include separate radio front-end circuitry 318, instead, the processing circuitry 302 includes radio front-end circuitry and is connected to the antenna 310. Similarly, in some embodiments, all or some of the RF transceiver circuitry 312 is part of the communication interface 306. In still other embodiments, the communication interface 306 includes one or more ports or terminals 316, the radio front-end circuitry 318, and the RF transceiver circuitry 312, as part of a radio unit (not shown), and the communication interface 306 communicates with the baseband processing circuitry 314, which is part of a digital unit (not shown).

[0103] The antenna 310 may include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. The antenna 310 may be coupled to the radio front-end circuitry 318 and may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In certain embodiments, the antenna 310 is separate from the network node 300 and connectable to the network node 300 through an interface or port.

[0104] The antenna 310, communication interface 306, and/or the processing circuitry 302 may be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by the network node. Any information, data and/or signals may be received from a UE, another network node and/or any other network equipment. Similarly, the antenna 310, the communication interface 306, and/or the processing circuitry 302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and/or signals may be transmitted to a UE, another network node and/or any other network equipment.

[0105] The power source 308 provides power to the various components of network node 300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 300 with power for performing the functionality described herein. For example, the network node 300 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 308. As a further example, the power source 308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0106] Embodiments of the network node 300 may include additional components beyond those shown in Figure 5 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, the network node 300 may include user interface equipment to allow input of information into the network node 300 and to allow output of information from the network node 300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 300.

[0107] Figure 6 is a block diagram of a host 400, which may be an embodiment of the host 116 of Figure 3, in accordance with various aspects described herein. As used herein, the host 400 may be or comprise various combinations hardware and/or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 400 may provide one or more services to one or more UEs.

[0108] The host 400 includes processing circuitry 402 that is operatively coupled via a bus 404 to an input/output interface 406, a network interface 408, a power source 410, and a memory 412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 10 and 3, such that the descriptions thereof are generally applicable to the corresponding components of host 400.

[0109] The memory 412 may include one or more computer programs including one or more host application programs 414 and data 416, which may include user data, e.g., data generated by a UE for the host 400 or data generated by the host 400 for a UE. Embodiments of the host 400 may utilize only a subset or all of the components shown. The host application programs 414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs 414 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 400 may select and/or indicate a different host for over-the-top services for a UE. The host application programs 414 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

[0110] Figure 7 is a block diagram illustrating a virtualization environment 500 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 500 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized.

[0111] Applications 502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein.

[0112] Hardware 504 includes processing circuitry, memory that stores software and/or instructions executable by hardware processing circuitry, and/or other hardware devices as described herein, such as a network interface, input/output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 508a and 508b (one or more of which may be generally referred to as VMs 508), and/or perform any of the functions, features and/or benefits described in relation with some embodiments described herein. The virtualization layer 506 may present a virtual operating platform that appears like networking hardware to the VMs 508.

[0113] The VMs 508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 506. Different embodiments of the instance of a virtual appliance 502 may be implemented on one or more of VMs 508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0114] In the context of NFV, a VM 508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 508, and that part of hardware 504 that executes that VM, be it hardware dedicated to that VM and/or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 508 on top of the hardware 504 and corresponds to the application 502.

[0115] Hardware 504 may be implemented in a standalone network node with generic or specific components. Hardware 504 may implement some functions via virtualization. Alternatively, hardware 504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 510, which, among others, oversees lifecycle management of applications 502. In some embodiments, hardware 504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 512 which may alternatively be used for communication between hardware nodes and radio units.

[0116] Figure 8 shows a communication diagram of a host 602 communicating via a network node 604 with a UE 606 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE 112a of Figure 3 and/or UE 200 of Figure 4), network node (such as network node 110a of Figure 3 and/or network node 300 of Figure 5), and host (such as host 116 of Figure 3 and/or host 400 of Figure 6) discussed in the preceding paragraphs will now be described with reference to Figure 8.

[0117] Like host 400, embodiments of host 602 include hardware, such as a communication interface, processing circuitry, and memory. The host 602 also includes software, which is stored in or accessible by the host 602 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE 606 connecting via an over-the-top (OTT) connection 650 extending between the UE 606 and host 602. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 650.

[0118] The network node 604 includes hardware enabling it to communicate with the host 602 and UE 606. The connection 660 may be direct or pass through a core network (like core network 106 of Figure 3) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

[0119] The UE 606 includes hardware and software, which is stored in or accessible by UE 606 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE 606 with the support of the host 602. In the host 602, an executing host application may communicate with the executing client application via the OTT connection 650 terminating at the UE 606 and host 602. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection 650 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection 650.

[0120] The OTT connection 650 may extend via a connection 660 between the host 602 and the network node 604 and via a wireless connection 670 between the network node 604 and the UE 606 to provide the connection between the host 602 and the UE 606. The connection 660 and wireless connection 670, over which the OTT connection 650 may be provided, have been drawn abstractly to illustrate the communication between the host 602 and the UE 606 via the network node 604, without explicit reference to any intermediary devices and the precise routing of messages via these devices. [0121] As an example of transmitting data via the OTT connection 650, in step 608, the host 602 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE 606. In other embodiments, the user data is associated with a UE 606 that shares data with the host 602 without explicit human interaction. In step 610, the host 602 initiates a transmission carrying the user data towards the UE 606. The host 602 may initiate the transmission responsive to a request transmitted by the UE 606. The request may be caused by human interaction with the UE 606 or by operation of the client application executing on the UE 606. The transmission may pass via the network node 604, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 612, the network node 604 transmits to the UE 606 the user data that was carried in the transmission that the host 602 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 614, the UE 606 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 606 associated with the host application executed by the host 602.

[0122] In some examples, the UE 606 executes a client application which provides user data to the host 602. The user data may be provided in reaction or response to the data received from the host 602. Accordingly, in step 616, the UE 606 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input/output interface of the UE 606. Regardless of the specific manner in which the user data was provided, the UE 606 initiates, in step 618, transmission of the user data towards the host 602 via the network node 604. In step 620, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 604 receives user data from the UE 606 and initiates transmission of the received user data towards the host 602. In step 622, the host 602 receives the user data carried in the transmission initiated by the UE 606.

[0123] One or more of the various embodiments improve the performance of OTT services provided to the UE 606 using the OTT connection 650, in which the wireless connection 670 forms the last segment. More precisely, the teachings of these embodiments may improve the data rate and latency and thereby provide benefits such as reduced user waiting time, better responsiveness, and better QoE.

[0124] In an example scenario, factory status information may be collected and analyzed by the host 602. As another example, the host 602 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 602 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 602 may store surveillance video uploaded by a UE. As another example, the host 602 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host 602 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and/or transmitting data.

[0125] In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 650 between the host 602 and UE 606, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host 602 and/or UE 606. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 650 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 650 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node 604. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host 602. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 650 while monitoring propagation times, errors, etc.

[0126] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and/or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0127] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device but are enjoyed by the computing device as a whole, and/or by end users and a wireless network generally.

[0128] Figure 9 is a flowchart illustrating an example method 900 in a target network node, according to certain embodiments. In particular embodiments, one or more steps of Figure 9 may be performed by network node 300 described with respect to Figure 5.

[0129] The method may begin at step 912, where the target network node (e.g., network node 300) receives a request from a source network node (e.g., network node 300) for a random access configuration for performing an early TA acquisition procedure. In some embodiments, the request may be based on a trigger at the source network node for causing a wireless device to perform early uplink synchronization (i.e., early TA acquisition). In particular embodiments, the request comprises any of the requests described with respect to the embodiments and examples described herein.

[0130] At step 914, the network node may store an association between the random access configuration and the source network node. In particular embodiments, the association between the random access configuration and the source network node is based on the random access preamble. In particular embodiments, the association may be a direct association between the random access and preamble and the source network node, and in other embodiments the association may be an indirect association including any one or more of the following examples. In one example, the target network node associates a mapping between a UE identifier, a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier. In one example, the target network node associates a mapping between a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier. In one example, the target network node associates a mapping between a UE identifier and a certain source network node identifier.

[0131] In particular embodiments, the network node associates the random access configuration and the source network node according to any of the embodiments and examples described herein.

[0132] At step 916, the network node transmits the random access configuration to the source network node. The random access configuration comprises a random access preamble to be transmitted by a wireless device. In particular embodiments, the random access configuration applies to all wireless devices served by the source network node, or a subset of wireless devices served by the source network node. In particular embodiments, the random access configuration includes any of the parameters described with respect to any of the embodiments and examples described herein.

[0133] After the source network node receives the random access configuration, the source network node may trigger the wireless device to perform an early TA acquisition procedure, in which case the method continues to step 918.

[0134] At step 918, the network node receives the random access preamble from the wireless device. Based on the received preamble, the method continues to steps 920 and 922.

[0135] At step 920, the network node identifies the source network node associated with the early TA acquisition procedure (e.g., by matching the random access preamble with an associated source network node). In particular embodiments, the network node identifies the source network node according to any of the embodiments and examples described herein.

[0136] At step 922, the network node transmits a TA value for the wireless device (e.g., determined based on the random access procedure initiated by the wireless device) to the source network node.

[0137] After the wireless device performs the early TA acquisition procedure, the wireless device may be ordered by the source network node to perform an LTM cell switch to the target network node using the TA value received at step 922, in which case the method continues to step 924.

[0138] At step 924, the network node may receive an uplink channel from the wireless device based on the TA value.

[0139] Modifications, additions, or omissions may be made to method 900 of Figure 9. Additionally, one or more steps in the method of Figure 9 may be performed in parallel or in any suitable order.

[0140] Figure 10 is a flowchart illustrating an example method 1000 in a source network node, according to certain embodiments. In particular embodiments, one or more steps of Figure 10 may be performed by network node 300 described with respect to Figure 5.

[0141] The method may begin at step 1012, where the source network node (e.g., network node 300) transmits a request to a target network node (e.g., network node 300) for a random access configuration for performing an early TA acquisition procedure.

[0142] At step 1014, the source network node receives the random access configuration from the target network node. The random access configuration comprises a random access preamble to be transmitted by a wireless device.

[0143] At step 1016, the source network node transmits an order to the wireless device to perform an early TA acquisition procedure with the target network node. The order comprises an indication of the random access preamble.

[0144] At step 1018, the source network node receives from the target network node a TA value for the wireless device. In particular embodiments, the source network node receives the TA value from the target network node based on the random access preamble transmitted by the wireless device in the previous step.

[0145] At step 1020, the source network node transmits an order to the wireless device to perform a LTM cell switch procedure to the target network node. The order comprises the TA value.

[0146] Modifications, additions, or omissions may be made to method 1000 of Figure 10. Additionally, one or more steps in the method of Figure 10 may be performed in parallel or in any suitable order.

[0147] In some embodiments, transmission and reception between the target network node, source network node, and a wireless device , as described with respect to Figures 9 and 10, may include a third network node, such as a gNB-CU, or any other suitable node.

[0148] The foregoing description sets forth numerous specific details. It is understood, however, that embodiments may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation. [0149] References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0150] Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the scope of this disclosure, as defined by the claims below.

[0151] Some example embodiments are described below.

Group A Embodiments

1. A method performed by a wireless device to acquire a timing advance (TA) value for use when executing a layer one/layer two triggered mobility (LTM) cell switch procedure, the method comprising:

- receiving from a source distributed unit (S-DU) a trigger to transmit a preamble for early uplink synchronization to an LTM candidate cell of a candidate distributed unit (C-DU);

- transmitting the preamble to the LTM candidate cell of the C-DU;

- receiving a TA value within an LTM cell switch command from the S-DU;

- applying the received TA value during the execution of an LTM cell switch procedure; and

- wherein the TA value is associated to the S-DU that triggered the wireless device to transmit the preamble for early uplink synchronization.

2. The method of the previous embodiment, wherein the TA value is associated to the S-DU that triggered the UE to transmit the preamble for early uplink synchronization based on the TA value is associated to a preamble that is indicated in a random access channel (RACH) configuration associated to the S-DU.

3. A method performed by a wireless device, the method comprising:

- any of the wireless device steps, features, or functions described above, either alone or in combination with other steps, features, or functions described above.

4. The method of the previous embodiment, further comprising one or more additional wireless device steps, features or functions described above.

5. The method of any of the previous embodiments, further comprising:

- providing user data; and

- forwarding the user data to a host computer via the transmission to the base station.

Group B Embodiments

6. A method performed by a source base station to provide a timing advance (TA) value to a wireless device within a layer one/layer two triggered mobility (LTM) cell switch command, the method comprising:

- determining that an early TA acquisition procedure needs to be initiated at a wireless device;

- transmitting to the wireless device signaling to initiate the early TA acquisition procedure;

- transmitting to a target network node or a third network node an indication about the information included in the signaling sent to the wireless device to initiate the early TA acquisition procedure; and

- receiving from the target network node or the third network node a TA value to be included within an LTM cell switch command sent to the wireless device to initiate an LTM cell switch procedure.

7. The method of the previous embodiment, wherein the information transmitted by the source base station to the third network node or the target network node is the same as the information sent to the wireless device in the signaling to initiate an early TA acquisition procedure. The method of embodiment 6, wherein the information transmitted by the source base station the third network node or the target network node is a subset of the information sent to the wireless device in the signaling to initiate an early TA acquisition procedure. The method of any one of the previous three embodiments, wherein the information transmitted by the source base station to the third network node or target network node includes one or more of the following:

- A preamble index ID,

- A source network node identifier,

- An synchronization signal block (SSB) index,

- A random access configuration identifier,

- A user equipment (UE) identifier, and

- An LTM candidate cell identifier. The method of any one of the previous four embodiments, wherein the source base station receives from the third network node or the target network node an indication with a TA value and which may include further one or more of the following:

- A TA value

- A UE identifier

- An LTM candidate cell identifier

- A preamble index ID

- A random access configuration identifier A method performed by a target base station to provide a timing advance (TA) value to a source network node so that the TA value may be provided to a wireless device within a layer one/layer two triggered mobility (LTM) cell switch command, the method comprising:

- receiving a request from a third network node or a source network node to provide a random access configuration for a wireless device to perform an early TA acquisition procedure;

- determining a random access configuration for executing an early TA acquisition procedure that may be used by wireless devices belonging to the source network node.

- transmitting the determined random access configuration to the source network node.

- receiving from the source network node an indication that an early TA acquisition procedure has been triggered at the wireless device;

- receiving a random access preamble from the wireless device;

- determining a TA value for the wireless device from which the random access preamble had been received;

- determining a source network node to which the determined TA value should be transmitted; and

- transmitting the determined TA value to the determined source network node. The method of the previous embodiment, wherein the target base station determines the random access configuration for the early TA acquisition procedure according to one or more of the following:

- the target base station generates a random access configuration that is used for a subset of wireless devices that are currently served by the source base station.

- the target base station generates a random access configuration that is used by all wireless devices of a source network node; and

- the target base station generates a random access configuration that is used by a subset of wireless devices of a source network node. The method of any one of the previous two embodiments, wherein the target base station transmits the determined random access configuration to the source network node and the indication may include one or more of:

- One or a list of UE identifiers for which a certain random access configuration is applicable;

- A random access configuration identifier; and

- One or a list of source network node identifiers for which a certain random access configuration is applicable. The method of any one of the previous three embodiments, wherein the target base station receives from the source network node or the third network node an indication that an early TA acquisition procedure has been triggered by the source network node to the wireless device, the indication comprising one or more of:

- A random access preamble identifier - A source network node identifier

- A SSB identifier

- A random access configuration identifier

- A LTM candidate cell identifier The method of any one of the previous four embodiments, wherein the target base station, after determining the TA value, determines the source network node to which the TA value should be sent according to one of more of the following:

- the target base station checks the mapping between a UE identifier, a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier;

- the target base station checks the mapping between a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier;

- the target base station checks the mapping between a UE identifier and a certain source network node identifier; and

- the target base station is informed by the source network node that an early TA acquisition procedure has been triggered to the wireless device and is informed about the information the source network node has included in the PDCCH order sent to the wireless device. A method performed by a (third) base station to provide a timing advance (TA) value to a source network node so that the TA value may be provided to a wireless device within a layer one/layer two triggered mobility (LTM) cell switch command, the method comprising:

- transmitting a request to a target network node to provide a random access configuration for a wireless device to perform an early TA acquisition procedure;

- receiving a random access configuration from the target network node;

- transmitting the received random access configuration to the source network node;

- receiving from the source network node an indication that an early TA acquisition procedure has been triggered at the wireless device.

- receiving a TA value from the target network node;

- determining the source network node to which the determined TA value should be transmitted; and - transmitting the determined TA value to the determined source network node. The method of the previous embodiment, wherein the base station, when transmitting the request to provide a random access configuration for an early TA acquisition procedure, further sends in the request a source network node identifier. The method of any one of the previous two embodiments, wherein the base station receives from the target network node a random access configuration for an early TA acquisition procedure and together with the configuration the base station may further receive one or more of the following information (linked to the received random access configuration):

- One or a list of UE identifiers for which a certain random access configuration is applicable

- A random access configuration identifier

- One or a list of source network node identifiers for which a certain random access configuration is applicable. The method of any one of the previous three embodiments, wherein the base station receives from the source network node an indication that an early TA acquisition procedure has been triggered by the source network node to the wireless device, the indication comprising one or more of:

- A random access preamble identifier

- A source network node identifier

- A SSB identifier

- A random access configuration identifier

- A LTM candidate cell identifier The method of any one of the previous four embodiments, wherein the base station, after receiving a TA value from the target network node, determines the source network node to which the TA value should be sent according to one of more of the following:

- the base station checks the mapping between a target network node, a random access configuration identifier (or the identifier of a field which is part of the random access configuration) and a source network node identifier,

- the base station checks the mapping between the target network node, a random access configuration identifier (or the identifier of a field which is part of the random access configuration), a source network node identifier, and a UE identifier.

- the base station checks the mapping between a UE identifier and a certain source network node identifier.

- the base station is informed by the source network node that a early TA acquisition procedure has been triggered to the UE and is informed about the information the source network node has included in the PDCCH order sent to the UE.

21. A method performed by a base station, the method comprising:

- any of the steps, features, or functions described above with respect to base stations, either alone or in combination with other steps, features, or functions described above.

22. The method of the previous embodiment, further comprising one or more additional base station steps, features or functions described above.

23. The method of any of the previous embodiments, further comprising:

- obtaining user data; and

- forwarding the user data to a host computer or a wireless device.

Group C Embodiments

24. A mobile terminal comprising:

- processing circuitry configured to perform any of the steps of any of the Group A embodiments; and

- power supply circuitry configured to supply power to the wireless device.

25. A base station comprising:

- processing circuitry configured to perform any of the steps of any of the Group B embodiments;

- power supply circuitry configured to supply power to the wireless device.

26. A user equipment (UE) comprising:

- an antenna configured to send and receive wireless signals;

- radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry;

- the processing circuitry being configured to perform any of the steps of any of the Group A embodiments;

- an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry;

- an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and

- a battery connected to the processing circuitry and configured to supply power to the UE. A communication system including a host computer comprising:

- processing circuitry configured to provide user data; and

- a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE),

- wherein the cellular network comprises a base station having a radio interface and processing circuitry, the base station’s processing circuitry configured to perform any of the steps of any of the Group B embodiments. The communication system of the pervious embodiment further including the base station. The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station. The communication system of the previous 3 embodiments, wherein:

- the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and

- the UE comprises processing circuitry configured to execute a client application associated with the host application. A method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:

- at the host computer, providing user data; and

- at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the base station performs any of the steps of any of the Group B embodiments. The method of the previous embodiment, further comprising, at the base station, transmitting the user data. The method of the previous 2 embodiments, wherein the user data is provided at the host computer by executing a host application, the method further comprising, at the UE, executing a client application associated with the host application. A user equipment (UE) configured to communicate with a base station, the UE comprising a radio interface and processing circuitry configured to performs any of the previous 3 embodiments. A communication system including a host computer comprising:

- processing circuitry configured to provide user data; and

- a communication interface configured to forward user data to a cellular network for transmission to a user equipment (UE),

- wherein the UE comprises a radio interface and processing circuitry, the UE’s components configured to perform any of the steps of any of the Group A embodiments. The communication system of the previous embodiment, wherein the cellular network further includes a base station configured to communicate with the UE. The communication system of the previous 2 embodiments, wherein:

- the UE’s processing circuitry is configured to execute a client application associated with the host application. A method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:

- at the host computer, providing user data; and

- at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the UE performs any of the steps of any of the Group A embodiments. The method of the previous embodiment, further comprising at the UE, receiving the user data from the base station. A communication system including a host computer comprising:

- communication interface configured to receive user data originating from a transmission from a user equipment (UE) to a base station,

- wherein the UE comprises a radio interface and processing circuitry, the UE’s processing circuitry configured to perform any of the steps of any of the Group A embodiments. The communication system of the previous embodiment, further including the UE. The communication system of the previous 2 embodiments, further including the base station, wherein the base station comprises a radio interface configured to communicate with the UE and a communication interface configured to forward to the host computer the user data carried by a transmission from the UE to the base station. The communication system of the previous 3 embodiments, wherein:

- the processing circuitry of the host computer is configured to execute a host application; and

- the UE’s processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data. The communication system of the previous 4 embodiments, wherein:

- the processing circuitry of the host computer is configured to execute a host application, thereby providing request data; and

- the UE’s processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data in response to the request data. A method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:

- at the host computer, receiving user data transmitted to the base station from the UE, wherein the UE performs any of the steps of any of the Group A embodiments. The method of the previous embodiment, further comprising, at the UE, providing the user data to the base station. The method of the previous 2 embodiments, further comprising:

- at the UE, executing a client application, thereby providing the user data to be transmitted; and

- at the host computer, executing a host application associated with the client application. The method of the previous 3 embodiments, further comprising:

- at the UE, executing a client application; and

- at the UE, receiving input data to the client application, the input data being provided at the host computer by executing a host application associated with the client application,

- wherein the user data to be transmitted is provided by the client application in response to the input data. A communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a user equipment (UE) to a base station, wherein the base station comprises a radio interface and processing circuitry, the base station’s processing circuitry configured to perform any of the steps of any of the Group B embodiments. The communication system of the previous embodiment further including the base station. The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station. The communication system of the previous 3 embodiments, wherein:

- the processing circuitry of the host computer is configured to execute a host application;

- the UE is configured to execute a client application associated with the host application, thereby providing the user data to be received by the host computer. A method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:

- at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE, wherein the UE performs any of the steps of any of the Group A embodiments. The method of the previous embodiment, further comprising at the base station, receiving the user data from the UE. The method of the previous 2 embodiments, further comprising at the base station, initiating a transmission of the received user data to the host computer.

Claims

1. A method performed by a target network node, the method comprising: receiving (912) a request from a source network node for a random access configuration for performing an early timing advance (TA) acquisition procedure; transmitting (916) the random access configuration to the source network node, the random access configuration comprising a random access preamble to be transmitted by a wireless device; receiving (918) the random access preamble from the wireless device; based on the received preamble: identifying (920) the source network node associated with the early TA acquisition procedure; and transmitting (922) a TA value for the wireless device to the source network node.

2. The method of claim 1, further comprising storing (914) an association between the random access configuration and the source network node.

3. The method of claim 2, wherein the association between the random access configuration and the source network node is based on the random access preamble.

4. The method of any one of claims 1-3, further comprising receiving (924) an uplink channel from the wireless device based on the TA value.

5. The method of any one of claims 1-4, wherein the random access configuration applies to all wireless devices served by the source network node.

6. The method of any one of claims 1-4, wherein the random access configuration applies to a subset of wireless devices served by the source network node.

7. A target network node (300) comprising processing circuitry (302), the processing circuitry operable to: receive a request from a source network node for a random access configuration for performing an early timing advance (TA) acquisition procedure; transmit the random access configuration to the source network node, the random access configuration comprising a random access preamble to be transmitted by a wireless device; receive the random access preamble from the wireless device; based on the received preamble: identify the source network node associated with the early TA acquisition procedure; and transmit a TA value for the wireless device to the source network node.

8. The network node of claim 7, the processing circuitry further operable to store an association between the random access configuration and the source network node.

9. The network node of claim 8, wherein the association between the random access configuration and the source network node is based on the random access preamble.

10. The network node of any one of claims 7-9, the processing circuitry further operable to receive an uplink channel from the wireless device based on the TA value.

11. The network node of any one of claims 7-10, wherein the random access configuration applies to all wireless devices served by the source network node.

12. The network node of any one of claims 7-10, wherein the random access configuration applies to a subset of wireless devices served by the source network node.

13. A method performed by a source network node, the method comprising: transmitting (1012) a request to a target network node for a random access configuration for performing an early timing advance (TA) acquisition procedure; receiving (1014) the random access configuration from the target network node, the random access configuration comprising a random access preamble to be transmitted by a wireless device; transmitting (1016) an order to the wireless device to perform an early TA acquisition procedure with the target network node, the order comprising an indication of the random access preamble; and receiving (1018) from the target network node a TA value for the wireless device.

14. The method of claim 13, wherein the source network node receives the TA value from the target network node based on the random access preamble transmitted by the wireless device.

15. The method of any one of claims 13-14, further comprising transmitting (1020) an order to the wireless device to perform a layer one/layer two triggered mobility (LTM) cell switch procedure to the target network node, the order comprising the TA value.

16. The method of any one of claims 13-15, wherein the random access configuration applies to all wireless devices served by the source network node.

17. The method of any one of claims 13-15, wherein the random access configuration applies to a subset of wireless devices served by the source network node.

18. A source network node (300) comprising processing circuitry (302), the processing circuitry operable to: transmit a request to a target network node (300) for a random access configuration for performing an early timing advance (TA) acquisition procedure; receive the random access configuration from the target network node, the random access configuration comprising a random access preamble to be transmitted by a wireless device (200); transmit an order to the wireless device to perform an early TA acquisition procedure with the target network node, the order comprising an indication of the random access preamble; and receive from the target network node a TA value for the wireless device.

19. The network node of claim 18, wherein the source network node receives the TA value from the target network node based on the random access preamble transmitted by the wireless device.

20. The network node of any one of claims 18-19, the processing circuitry further operable to transmit an order to the wireless device to perform a layer one/layer two triggered mobility (LTM) cell switch procedure to the target network node, the order comprising the TA value.

21. The network node of any one of claims 18-20, wherein the random access configuration applies to all wireless devices served by the source network node.

22. The network node of any one of claims 18-20, wherein the random access configuration applies to a subset of wireless devices served by the source network node.