Apparatus, method, and computer program

Abstract

Provided are a method, a computer program, and an apparatus for causing an apparatus of a second access node to cause a first timing advance value to be provided to a user equipment to enable the user equipment to synchronize uplink transmissions to the timing of a target cell supported by the second access node, determine a validity time of the first timing advance value, after which the first timing advance value is considered invalid, and signal the validity time to a first access node supporting a serving cell connected to the user equipment.

Description

Technical Field

[0001] The examples described in this specification generally relate to apparatuses, methods, and computer programs, and more particularly (but not exclusively) to apparatuses, methods for apparatuses, and computer programs.

Background Art

[0002] A communication system can be regarded as a facility that enables a communication session between two or more entities such as communication devices, base stations, and / or other nodes by providing a carrier between various entities included in a communication path.

[0003] The communication system may be a wireless communication system. Examples of wireless systems include terrestrial public mobile communication networks (PLMNs) operating based on wireless standards such as those provided by 3GPP, satellite-based communication systems, and different wireless local networks such as, for example, wireless local area networks (WLAN). The wireless system can typically be divided into cells and is thus often referred to as a cellular system.

[0004] Communication systems and associated devices typically operate according to a given standard or specification that defines what various entities associated with the system are enabled to do and how this should be achieved. Communication protocols and / or parameters that must be used for connections are also typically defined. An example of a standard is the so-called 5G standard.

Summary of the Invention

[0005] According to a first aspect, a device for a first access node is provided, the device comprising means for establishing a connection to a user device via a serving cell supported by the first access node, commanding the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell, receiving an indication from the second access node that the first timing advance value is invalid or will soon become invalid, and determining whether to command the user device to obtain a second timing advance value of the target cell in accordance with the received indication, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0006] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0007] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the target cell received by the user device is below a predetermined threshold.

[0008] An indication that the first timing advance value is no longer valid or will become invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0009] The device may include means for signaling a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been commanded to reacquire the timing advance of the target cell.

[0010] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0011] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0012] According to a second aspect, a device for a second access node is provided, the device comprising means for providing a first timing advance value to the user device to enable the user device to synchronize its uplink transmission to the timing of a target cell supported by the second access node; determining the validity period of the first timing advance value, such that the first timing advance value is deemed invalid after the validity period; and signaling to the first access node supporting a serving cell connected to the user device that the first timing advance value is invalid or will soon be invalid before or at the expiration of the validity period.

[0013] The device may include means for receiving a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance of the target cell.

[0014] The response may indicate that the user device has been instructed to reacquire the timing advance of the target cell, and the device may include means for providing the user device with a second timing advance value to enable the user device to synchronize its uplink transmission to the timing of the target cell supported by the second access node.

[0015] According to a third aspect, a device for a first access node is provided, the device comprising at least one processor and at least one memory, the device comprising at least one memory, which, when executed by the at least one processor, causes the device to perform the following actions: instruct the user device to obtain a first timing advance value of a target cell supported by a second access node, instructing the device to obtain a first timing advance value that indicates the timing for sending an uplink transmission to the target cell; receiving an indication from the second access node that the first timing advance value is invalid or will soon become invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in accordance with the received indication, instructing the device to determine that the second timing advance value is obtained later in time than the first timing advance value.

[0016] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0017] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the target cell received by the user device is below a predetermined threshold.

[0018] An indication that the first timing advance value is no longer valid or will become invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0019] The device may be configured to signal a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance for the target cell.

[0020] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0021] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0022] According to a fourth aspect, a device for a second access node is provided, the device comprising at least one processor and at least one memory, the device having software code that, when executed by the at least one processor, causes the device to perform the following actions: provide a first timing advance value to a user device to enable the user device to synchronize uplink transmissions to the timing of a target cell supported by the second access node; determine the validity period of the first timing advance value, which is deemed to be invalid after the validity period; and signal to the first access node supporting a serving cell connected to the user device that the first timing advance value is invalid or will soon be invalid before or at the expiration of the validity period.

[0023] The device may be made to receive a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance for the target cell.

[0024] The response may indicate that the user device has been instructed to reacquire the timing advance of the target cell, and the device may be instructed to ensure that a second timing advance value is provided to the user device, enabling the user device to synchronize its uplink transmission to the timing of the target cell supported by the second access node.

[0025] According to a fifth aspect, a method for an apparatus for a first access node is provided. The method includes establishing a connection to a user equipment via a serving cell supported by the first access node, and instructing the user equipment to obtain a first timing advance value of a target cell supported by a second access node, where the first timing advance value indicates timing for transmitting an uplink transmission to the target cell. The method further includes receiving, from the second access node, an indication that the first timing advance value is about to become invalid or has just become invalid, and determining whether to instruct the user equipment to obtain a second timing advance value of the target cell in response to the received indication, where the second timing advance value is obtained later in time than the first timing advance value.

[0026] The method may include receiving, from the user equipment, a first indication of the current strength and / or quality of a signal of the target cell received by the user equipment. Determining whether to instruct the user equipment may include determining to instruct the user equipment to obtain the second timing advance value when the first indication indicates that the current strength and / or quality of the signal provided by the target cell received by the user equipment has increased beyond a predetermined threshold.

[0027] The method may include receiving, from the user equipment, a first indication of the current strength and / or quality of a signal of the target cell received by the user equipment. Determining whether to instruct the user equipment may include determining to instruct the user equipment to release the first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user equipment is below a predetermined threshold.

[0028] An indication that the first timing advance value is no longer valid or becomes invalid when the user equipment transmits an uplink to a target cell can be received indirectly from a second access node via a centralized unit.

[0029] The method can include signaling a response to an indication that the first timing advance value is invalid or about to become invalid, the response including an indication as to whether the user equipment has been instructed to reacquire the timing advance of the target cell.

[0030] The method can include receiving from the user equipment a first indication of the current strength and / or quality of a signal of a target cell received by the user equipment, the first indication being received in a layer 1 measurement report.

[0031] Instructing the user equipment to obtain the first timing advance value can be performed in response to receiving from the user equipment a layer 1 measurement report indicating that the strength and / or quality of a signal provided by the target cell has exceeded a preconfigured threshold.

[0032] According to a sixth aspect, a method is provided for an apparatus for a second access node, the method comprising causing a first timing advance value to be provided to the user equipment to enable the user equipment to synchronize an uplink transmission to the timing of a target cell supported by the second access node; determining a validity period for the first timing advance value, wherein the first timing advance value is considered invalid after the validity period; and signaling to a first access node supporting a serving cell connected to the user equipment an indication that the first timing advance value is invalid or about to become invalid before or at the expiration of the validity period.

[0033] The method may include receiving a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance for the target cell.

[0034] The response may indicate that the user device has been instructed to reacquire the timing advance of the target cell, and the method may include providing the user device with a second timing advance value to enable the user device to synchronize its uplink transmission to the timing of the target cell supported by the second access node.

[0035] According to a seventh aspect, a device for a first access node is provided, the device comprising: an establishment circuit device for establishing a connection to a user device via a serving cell supported by the first access node; an instruction circuit device for instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; a receiving circuit device for receiving a decision circuit device from the second access node for an indication that the first timing advance value is invalid or will soon be invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in accordance with the received indication, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0036] The device may include a receiving circuit device for receiving from the user device a first indication of the current intensity and / or quality of the signal of a target cell received by the user device, and a decision circuit device for determining whether to instruct the user device may include a decision circuit device for determining whether to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0037] The device may include a receiving circuit device for receiving from the user device a first indication of the current strength and / or quality of the signal of the target cell received by the user device, and a decision circuit device for determining whether to command the user device may include a decision circuit device for determining whether to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold.

[0038] An indication that the first timing advance value is no longer valid or will become invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0039] The device may include signaling circuit equipment for signaling a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user equipment has been commanded to reacquire the timing advance of the target cell.

[0040] The device may include a receiving circuit device for receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0041] An instruction circuit device for instructing a user device to obtain a first timing advance value may operate in response to receiving a Layer 1 measurement report from the user device that indicates that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0042] According to the eighth aspect, a device for a second access node is provided, the device comprising: a source circuit device for providing a first timing advance value to a user device to enable the user device to synchronize its uplink transmission to the timing of a target cell supported by the second access node; a determination circuit device for determining the validity period of the first timing advance value, wherein the first timing advance value is deemed invalid after the validity period; and a signaling circuit device for signaling to the first access node supporting a serving cell connected to the user device that the first timing advance value is invalid or will soon be invalid before or at the expiration of the validity period.

[0043] The device may include a receiving circuit device for receiving a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance of the target cell.

[0044] The response may indicate that the user device has been commanded to reacquire the timing advance of the target cell, and the device may include initiating circuitry to provide the user device with a second timing advance value to enable the user device to synchronize its uplink transmission to the timing of the target cell supported by the second access node.

[0045] According to the ninth aspect, a non-temporary computer-readable medium is provided, comprising program instructions for a device for a first access node to perform the following actions: establishing a connection to a user device via a serving cell supported by a first access node; instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; receiving an indication from the second access node that the first timing advance value is invalid or will soon become invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in accordance with the received indication, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0046] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0047] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the target cell received by the user device is below a predetermined threshold.

[0048] An indication that the first timing advance value is no longer valid or will become invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0049] The device may be configured to signal a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance for the target cell.

[0050] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0051] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0052] According to a tenth aspect, a non-temporary computer-readable medium is provided, comprising program instructions for causing a device for a second access node to perform the following actions: providing a first timing advance value to a user device to enable the user device to synchronize its uplink transmission to the timing of a target cell supported by the second access node; determining the validity period of the first timing advance value, such that the first timing advance value is considered invalid after the validity period; and signaling to the first access node supporting a serving cell connected to the user device that the first timing advance value is invalid or will soon be invalid before or at the expiration of the validity period.

[0053] The device may be made to receive a response to an indication that a first timing advance value is invalid or will soon become invalid, the response including an indication that the user device has been instructed to reacquire the timing advance for the target cell.

[0054] The response may indicate that the user device has been instructed to reacquire the timing advance of the target cell, and the device may be instructed to ensure that a second timing advance value is provided to the user device, enabling the user device to synchronize its uplink transmission to the timing of the target cell supported by the second access node.

[0055] According to the eleventh aspect, a device for a first access node is provided, the device comprising means for establishing a connection to a user device via a serving cell supported by the first access node, commanding the user device to obtain a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell, receiving an indication from the second access node about when the first timing advance value will become invalid, using the indication about when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid, and determining whether to command the user device to obtain a second timing advance value of the target cell in response to the use thereof, the second timing advance value being obtained later in time than the first timing advance value.

[0056] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0057] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device is below a predetermined threshold.

[0058] An indication of when the first timing advance value becomes invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0059] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may include means for using the timer value to start the timer and for determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0060] When the device includes means for receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, the first indication may be received in a Layer 1 measurement report.

[0061] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0062] According to a twelfth aspect, a device for a second access node is provided, the device comprising means for providing a first timing advance value to the user device to enable the user device to synchronize its uplink transmission to the timing of a target cell supported by the second access node; determining the validity period of the first timing advance value, such that the first timing advance value is deemed invalid after the validity period; and signaling the validity period to the first access node supporting a serving cell connected to the user device.

[0063] According to the 13th aspect, a device for a first access node is provided, the device comprising at least one processor and at least one memory, which, when executed by the at least one processor, causes the device to perform the following actions: establish a connection to a user device via a serving cell supported by the first access node; instruct the user device to obtain a first timing advance value of a target cell supported by a second access node, which indicates the timing for sending an uplink transmission to the target cell; receive an indication from the second access node about when the first timing advance value will become invalid; use the indication about when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and determine whether, in response to such use, the device should be instructed to obtain a second timing advance value of the target cell, which determines that the second timing advance value is obtained later in time than the first timing advance value.

[0064] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0065] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device is below a predetermined threshold.

[0066] An indication of when the first timing advance value becomes invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0067] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may be made to use the timer value to start the timer and, in response to the timer's expiration, determine that the first timing advance value is invalid or will soon become invalid.

[0068] When the device is configured to receive a first indication from the user device regarding the current intensity and / or quality of the signal of the target cell received by the user device, the first indication may be received in a Layer 1 measurement report.

[0069] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0070] According to a fourteenth aspect, a device for a second access node is provided, the device comprising at least one processor and at least one memory, the device comprising, when executed by the at least one processor, software code causing the device to perform the following actions: providing a first timing advance value to a user device so as to enable the user device to synchronize uplink transmissions to the timing of a target cell supported by the second access node; determining the validity period of the first timing advance value, which is deemed invalid after the validity period; and signaling the validity period to a first access node supporting a serving cell connected to the user device.

[0071] According to the 15th aspect, a method is provided for a device for a first access node, the method comprising: establishing a connection to a user device via a serving cell supported by the first access node; instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication from the second access node about when the first timing advance value will become invalid; using the indication about when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in response to such use, the second timing advance value being obtained later in time than the first timing advance value.

[0072] The method may include receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0073] The method may include receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device is below a predetermined threshold.

[0074] An indication of when the first timing advance value becomes invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0075] An indication of when the first timing advance value becomes invalid may include a timer value, and the method may include starting a timer using the timer value and determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0076] When the method includes receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, the first indication may be received in a Layer 1 measurement report.

[0077] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0078] According to the 16th aspect, a method is provided for a device for a second access node, the method comprising: providing a first timing advance value to a user device to enable the user device to synchronize its uplink transmission to the timing of a target cell supported by the second access node; determining an effective time for the first timing advance value such that the first timing advance value is deemed invalid after the effective time; and signaling the effective time to a first access node supporting a serving cell connected to the user device.

[0079] According to the 17th aspect, a device for a first access node is provided, the device comprising: an establishment circuit device for establishing a connection to a user device via a serving cell supported by the first access node; an instruction circuit device for instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; a receiving circuit device for receiving an indication from the second access node about when the first timing advance value will become invalid; and a decision circuit device for determining whether to use the indication about when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid, and whether to instruct the user device to obtain a second timing advance value of the target cell in response to such use, wherein the second timing advance value is obtained in time later than the first timing advance value.

[0080] The device may include a receiving circuit device for receiving from the user device a first indication of the current intensity and / or quality of the signal of a target cell received by the user device, and a decision circuit device for determining whether to instruct the user device may include a decision circuit device for determining whether to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0081] The device may include a receiving circuit device for receiving from the user device a first indication of the current strength and / or quality of the signal of the target cell received by the user device, and a decision circuit device for determining whether to command the user device may include a decision circuit device for determining whether to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the signal provided by the target cell received by the user device is below a predetermined threshold.

[0082] An indication of when the first timing advance value becomes invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0083] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may include a start circuit device for starting the timer using the timer value, and a decision circuit device for determining whether the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0084] When the device includes a receiving circuit device for receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, the first indication may be received in a Layer 1 measurement report.

[0085] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0086] According to the 18th aspect, a device for a second access node is provided, the device comprising: a source circuit device for providing a first timing advance value to a user device so that the user device can synchronize its uplink transmission to the timing of a target cell supported by the second access node; a determination circuit device for determining the validity period of the first timing advance value, wherein the first timing advance value is deemed invalid after the validity period; and a signaling circuit device for signaling the validity period to a first access node supporting a serving cell connected to the user device.

[0087] According to the 19th aspect, a non-temporary computer-readable medium is provided, comprising program instructions for causing a device for a first access node to perform the following actions: establishing a connection to a user device via a serving cell supported by a first access node; instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates the timing for sending an uplink transmission to the target cell; receiving an indication from the second access node about when the first timing advance value will become invalid; using the indication about when the first timing advance value will become invalid to determine whether the user device should be instructed to obtain a second timing advance value of the target cell in response to the use thereof, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0088] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0089] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell received by the user device is below a predetermined threshold.

[0090] An indication of when the first timing advance value becomes invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0091] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may be made to use the timer value to start the timer and, in response to the timer's expiration, determine that the first timing advance value is invalid or will soon become invalid.

[0092] When the device is configured to receive a first indication from the user device regarding the current intensity and / or quality of the signal of the target cell received by the user device, the first indication may be received in a Layer 1 measurement report.

[0093] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0094] According to a 20th aspect, a non-temporary computer-readable medium is provided, comprising program instructions for causing a device for a second access node to perform the following actions: providing a first timing advance value to a user device to enable the user device to synchronize its uplink transmission to the timing of a target cell supported by the second access node; determining the validity period of the first timing advance value, wherein the first timing advance value is deemed invalid after the validity period; and signaling the validity period to the first access node supporting a serving cell connected to the user device.

[0095] According to the 21st aspect, a device for a first access node is provided, the device comprising means for establishing a connection to a user device via a serving cell supported by the first access node, commanding the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell, receiving an indication from the user device that the first timing advance value is invalid or will soon become invalid, and determining whether to command the user device to obtain a second timing advance value of the target cell in accordance with the received indication, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0096] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0097] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device is below a predetermined threshold.

[0098] The apparatus may be equipped with means for receiving a first indication in the layer 1 measurement report.

[0099] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0100] According to the 22nd aspect, a device for user equipment is provided, the device comprising means for obtaining a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid; and signaling the serving cell supported by the first access node to the indication that the first timing advance value is invalid or will soon become invalid in response to the use thereof.

[0101] The device may include means for signaling a serving cell a first indication of the current intensity and / or quality of the signal from the target cell received by the user device, the first indication being signaled in a Layer 1 measurement report.

[0102] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may include means for using the timer value to start the timer and for determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0103] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0104] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0105] The device may include means for receiving a command from a serving cell to acquire a second timing advance value, wherein the second timing advance value is acquired later in time than the first timing advance value, and for acquiring the second timing advance value in response to the command.

[0106] The device may include means for receiving a command from a serving cell to release a first timing advance value and for releasing the first timing advance value.

[0107] According to the 23rd aspect, a device for a first access node is provided, the device comprising at least one processor and at least one memory, the device comprising at least one memory, which, when executed by the at least one processor, causes the device to perform the following actions: instruct the user device to obtain a first timing advance value of a target cell supported by a second access node, instructing the device to instruct the user device to obtain a first timing advance value of a target cell supported by a second access node, indicating that the first timing advance value indicates a timing for sending an uplink transmission to the target cell; receiving an indication from the user device that the first timing advance value is invalid or will soon become invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in accordance with the received indication, in determining that the second timing advance value is obtained in time later than the first timing advance value.

[0108] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0109] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device is below a predetermined threshold.

[0110] The device may be configured to receive a first indication in the layer 1 measurement report.

[0111] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0112] According to the 24th aspect, a device for user equipment is provided, the device comprising at least one processor and at least one memory, which, when executed by the at least one processor, causes the device to perform the following actions: acquire a first timing advance value of a target cell supported by a second access node, the first timing advance value indicates a timing for sending an uplink transmission to the target cell; receive an indication of when the first timing advance value will become invalid; use the indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid; and signal to a serving cell supported by the first access node in response to such use.

[0113] The device may be configured to signal a serving cell a first indication of the current intensity and / or quality of the signal from the target cell received by the user device, the first indication being signaled in a Layer 1 measurement report.

[0114] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may be made to use the timer value to start the timer and, in response to the timer's expiration, determine that the first timing advance value is invalid or will soon become invalid.

[0115] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0116] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0117] The device may receive a command from a serving cell to acquire a second timing advance value, wherein the second timing advance value is acquired later in time than the first timing advance value, and may perform the actions of receiving the command and acquiring the second timing advance value in response to the command.

[0118] The device may be instructed to receive a command from the serving cell to release the first timing advance value and to release the first timing advance value.

[0119] According to the 25th aspect, a method is provided for a device for a first access node, the method comprising: establishing a connection to a user device via a serving cell supported by the first access node; instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication from the user device that the first timing advance value is invalid or will soon become invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in response to the received indication, the second timing advance value being obtained later in time than the first timing advance value.

[0120] The method may include receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0121] The method may include receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device may include deciding to instruct the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device is below a predetermined threshold.

[0122] The method may include receiving a first indication in a Layer 1 measurement report.

[0123] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0124] According to the 26th aspect, a method is provided for a device for user equipment, the method comprising: obtaining a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid; and signaling the serving cell supported by the first access node to an indication that the first timing advance value is invalid or will soon become invalid in response to the use thereof.

[0125] The method may include signaling a serving cell with a first indication of the current intensity and / or quality of the signal from the target cell received by the user equipment, the first indication being signaled in a Layer 1 measurement report.

[0126] An indication of when the first timing advance value becomes invalid may include a timer value, and the method may include starting a timer using the timer value and determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0127] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0128] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0129] The method may include receiving a command from a serving cell to obtain a second timing advance value, wherein the second timing advance value is obtained later in time than the first timing advance value, and obtaining the second timing advance value in response to the command.

[0130] The method may include receiving a command from the serving cell to release the first timing advance value, and then releasing the first timing advance value.

[0131] According to the 27th aspect, a device for a first access node is provided, the device comprising: an establishment circuit device for establishing a connection to a user device via a serving cell supported by the first access node; an instruction circuit device for instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; a receiving circuit device for receiving an indication from the user device that the first timing advance value is invalid or will soon become invalid; and a decision circuit device for determining whether to instruct the user device to obtain a second timing advance value of the target cell in response to the received indication, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0132] The device may include a receiving circuit device for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and a decision circuit device for determining whether to command the user device may include a decision circuit device for determining whether to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0133] The device may include a receiving circuit device for receiving from the user device a first indication of the current strength and / or quality of the signal of the target cell received by the user device, and a decision circuit device for determining whether to command the user device may include a decision circuit device for determining whether to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device is below a predetermined threshold.

[0134] The apparatus may be equipped with a receiving circuit device for receiving a first indication in the layer 1 measurement report.

[0135] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0136] According to the 28th aspect, a device for user equipment is provided, the device comprising: an acquisition circuit device for acquiring a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; a receiving circuit device for receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and signaling to a serving cell supported by the first access node in response to such use that the first timing advance value is invalid or will soon become invalid.

[0137] The device may include signaling circuit equipment for signaling a serving cell a first indication of the current strength and / or quality of the signal from the target cell received by the user equipment, the first indication being signaled in the Layer 1 measurement report.

[0138] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may include a start circuit device for starting the timer using the timer value, and a decision circuit device for determining whether the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0139] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0140] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0141] The device may include a receiving circuit device for receiving a command from a serving cell to acquire a second timing advance value, wherein the second timing advance value is acquired later in time than the first timing advance value, and an acquisition circuit device for acquiring the second timing advance value in response to the command.

[0142] The device may include a receiving circuit device for receiving a command from a serving cell to release a first timing advance value, and a device for releasing the first timing advance value.

[0143] According to the 29th aspect, a non-temporary computer-readable medium is provided, comprising program instructions for a device for a first access node to perform the following actions: establishing a connection to a user device via a serving cell supported by a first access node; instructing the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; receiving an indication from the user device that the first timing advance value is invalid or will soon become invalid; and determining whether to instruct the user device to obtain a second timing advance value of the target cell in accordance with the received indication, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0144] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to obtain a second timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0145] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, and determining whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current intensity and / or quality of the signal of the target cell received by the user device is below a predetermined threshold.

[0146] The device may be configured to receive a first indication in the layer 1 measurement report.

[0147] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0148] According to the 30th aspect, a non-temporary computer-readable medium is provided, comprising program instructions for causing a device for user equipment to perform the following actions: obtaining a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid; and signaling to a serving cell supported by the first access node in response to the use of the indication that the first timing advance value is invalid or will soon become invalid.

[0149] The device may be configured to signal a serving cell a first indication of the current intensity and / or quality of the signal from the target cell received by the user device, the first indication being signaled in a Layer 1 measurement report.

[0150] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may be made to use the timer value to start the timer and, in response to the timer's expiration, determine that the first timing advance value is invalid or will soon become invalid.

[0151] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0152] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0153] The device may receive a command from a serving cell to acquire a second timing advance value, wherein the second timing advance value is acquired later in time than the first timing advance value, and may perform the actions of receiving the command and acquiring the second timing advance value in response to the command.

[0154] The device may be instructed to receive a command from the serving cell to release the first timing advance value and to release the first timing advance value.

[0155] According to the 31st aspect, a device for user equipment is provided, the device comprising means for receiving a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and determining whether to autonomously initiate acquisition of a second timing advance value of the target cell in response to the determination of whether the first timing advance value is invalid or will soon become invalid, the second timing advance value being acquired later in time than the first timing advance value.

[0156] The decision of whether to autonomously initiate the acquisition of a second timing absentee value may further depend on the current intensity and / or quality of the signal from the target cell received by the user equipment.

[0157] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may include means for using the timer value to start the timer and for determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0158] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0159] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0160] The device may include means for determining to autonomously start acquiring a second timing advance value for a target cell when it is determined that a first timing advance value is invalid or will soon become invalid, and for acquiring the second timing advance value in response to the decision to autonomously start acquiring it.

[0161] The device may include means for determining not to acquire a second timing advance value for a target cell when the current intensity and / or quality of the signal provided by the target cell is below a predetermined threshold, and for releasing the first timing advance value in response to the decision not to acquire the second timing advance value.

[0162] Whether to autonomously initiate the acquisition of a second timing advance value for the target cell may further depend on whether the user device has received a command from the serving cell to release the first timing advance value.

[0163] According to the 32nd aspect, a device for user equipment is provided, the device comprising at least one processor and at least one memory, which, when executed by the at least one processor, causes the device to receive a first timing advance value of a target cell supported by a second access node, which indicates the timing for sending an uplink transmission to the target cell; receive an indication of when the first timing advance value will become invalid; use the indication of when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and, in response to the determination of whether the first timing advance value is invalid or will soon become invalid, autonomously initiate the acquisition of a second timing advance value of the target cell, which determines that the second timing advance value is acquired later than the first timing advance value.

[0164] The decision of whether to autonomously initiate the acquisition of a second timing absentee value may further depend on the current intensity and / or quality of the signal from the target cell received by the user equipment.

[0165] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may be made to use the timer value to start the timer and, in response to the timer's expiration, determine that the first timing advance value is invalid or will soon become invalid.

[0166] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0167] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0168] The device may be configured to decide to autonomously start acquiring a second timing advance value for a target cell when it determines that the first timing advance value is invalid or will soon become invalid, and to acquire the second timing advance value in response to the decision to autonomously start acquiring it.

[0169] The device may be configured to decide not to acquire a second timing advance value for a target cell when the current intensity and / or quality of the signal provided by the target cell is below a predetermined threshold, and to release the first timing advance value in response to the decision not to acquire the second timing advance value.

[0170] Whether to autonomously initiate the acquisition of a second timing advance value for the target cell may further depend on whether the user device has received a command from the serving cell to release the first timing advance value.

[0171] According to the 33rd aspect, a method is provided for a device for user equipment, the method comprising: receiving a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and determining whether, in response to the determination of whether the first timing advance value is invalid or will soon become invalid, the method is to autonomously initiate obtaining a second timing advance value of the target cell, the second timing advance value being obtained later in time than the first timing advance value.

[0172] The decision of whether to autonomously initiate the acquisition of a second timing absentee value may further depend on the current intensity and / or quality of the signal from the target cell received by the user equipment.

[0173] An indication of when the first timing advance value becomes invalid may include a timer value, and the method may include starting a timer using the timer value and determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0174] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0175] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0176] The method may include deciding to autonomously begin retrieving a second timing advance value for a target cell when it is determined that the first timing advance value is invalid or will soon become invalid, and retrieving the second timing advance value in response to the decision to autonomously begin retrieving it.

[0177] The method may include deciding not to acquire a second timing advance value for a target cell when the current intensity and / or quality of the signal provided by the target cell is below a predetermined threshold, and releasing the first timing advance value in response to the decision not to acquire the second timing advance value.

[0178] Whether to autonomously initiate the acquisition of a second timing advance value for the target cell may further depend on whether the user device has received a command from the serving cell to release the first timing advance value.

[0179] According to the 34th aspect, a device for user equipment is provided, the device comprising: a receiving circuit device for receiving a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; a receiving circuit device for receiving an indication of when the first timing advance value will become invalid; a usage circuit device for using the indication of when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and a decision circuit device for determining whether to autonomously initiate acquisition of a second timing advance value of the target cell in response to the determination of whether the first timing advance value is invalid or will soon become invalid, wherein the second timing advance value is acquired in time later than the first timing advance value.

[0180] The decision of whether to autonomously initiate the acquisition of a second timing absentee value may further depend on the current intensity and / or quality of the signal from the target cell received by the user equipment.

[0181] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may include a start circuit device for starting the timer using the timer value, and a decision circuit device for determining whether the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0182] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0183] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0184] The device may include a decision circuit device for determining to autonomously start acquiring a second timing advance value for a target cell when it is determined that a first timing advance value is invalid or will soon become invalid, and an acquisition circuit device for acquiring the second timing advance value in response to the decision to autonomously start acquiring it.

[0185] The device may include a decision circuit device for determining whether to acquire a second timing advance value for a target cell when the current intensity and / or quality of the signal provided by the target cell is below a predetermined threshold, and a release circuit device for releasing the first timing advance value in response to the decision not to acquire the second timing advance value.

[0186] Whether to autonomously initiate the acquisition of a second timing advance value for the target cell may further depend on whether the user device has received a command from the serving cell to release the first timing advance value.

[0187] According to the 35th aspect, a non-temporary computer-readable medium is provided, comprising program instructions for causing a device for user equipment to perform the following actions: receiving a first timing advance value of a target cell supported by a second access node, the first timing advance value indicating a timing for sending an uplink transmission to the target cell; receiving an indication of when the first timing advance value will become invalid; using the indication of when the first timing advance value will become invalid to determine whether the first timing advance value is invalid or will soon become invalid; and determining whether to autonomously initiate acquiring a second timing advance value of the target cell, in response to the determination of whether the first timing advance value is invalid or will soon become invalid, the second timing advance value being acquired later in time than the first timing advance value.

[0188] The decision of whether to autonomously initiate the acquisition of a second timing absentee value may further depend on the current intensity and / or quality of the signal from the target cell received by the user equipment.

[0189] An indication of when the first timing advance value becomes invalid may include a timer value, and the device may be made to use the timer value to start the timer and, in response to the timer's expiration, determine that the first timing advance value is invalid or will soon become invalid.

[0190] An indication of when the first timing advance value becomes invalid can be obtained before the first timing advance value is acquired.

[0191] An indication of when the first timing advance value becomes invalid can be provided in the configuration for mobility triggered at the lower tier.

[0192] The device may be configured to decide to autonomously start acquiring a second timing advance value for a target cell when it determines that the first timing advance value is invalid or will soon become invalid, and to acquire the second timing advance value in response to the decision to autonomously start acquiring it.

[0193] The device may be configured to decide not to acquire a second timing advance value for a target cell when the current intensity and / or quality of the signal provided by the target cell is below a predetermined threshold, and to release the first timing advance value in response to the decision not to acquire the second timing advance value.

[0194] Whether to autonomously initiate the acquisition of a second timing advance value for the target cell may further depend on whether the user device has received a command from the serving cell to release the first timing advance value.

[0195] According to the 36th aspect, a device for a first access node is provided, the device comprising means for establishing a connection to a user device via a serving cell supported by the first access node, receiving configuration information having at least one indication of the validity period of a timing advance value associated with a target cell supported by a second access node, and commanding the user device to obtain a first timing advance value of the target cell, wherein the first timing advance value indicates the timing for sending an uplink transmission to the target cell, and monitoring the validity of the first timing advance value using its validity period.

[0196] The device may include means for determining that the monitoring indicates that a first timing advance value is invalid or will soon become invalid, and for determining whether to instruct a user device to acquire a second timing advance value for the target cell in response to the determination that the first timing advance value is invalid or will soon become invalid, wherein the determination is made that the second timing advance value is acquired later in time than the first timing advance value.

[0197] Deciding whether to instruct the user device may include receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, and deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0198] Determining whether to command the user device may include receiving a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device, and deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold.

[0199] An indication of when the first timing advance value becomes invalid may include a timer value, and the means for monitoring may include means for starting the timer using the timer value and determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0200] The device may include means for receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0201] Receiving configuration information may include receiving configuration information from a centralized unit.

[0202] According to the 37th aspect, a device for a first access node is provided, the device comprising at least one processor and at least one memory, which, when executed by the at least one processor, establishes a connection to user equipment via a serving cell supported by the first access node, receives configuration information having at least one indication of the validity period of a timing advance value associated with a target cell supported by a second access node, and instructs user equipment to obtain a first timing advance value of the target cell, wherein the first timing advance value instructs the device to instruct the device to indicate the timing for sending an uplink transmission to the target cell, and monitor the validity of the first timing advance value using its validity period.

[0203] The device may be made to determine that the monitoring indicates that a first timing advance value is invalid or will soon become invalid, and to determine whether to instruct the user device to acquire a second timing advance value for the target cell in response to the determination that the first timing advance value is invalid or will soon become invalid, wherein the second timing advance value is acquired later in time than the first timing advance value.

[0204] Deciding whether to instruct the user device may include receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, and deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0205] Determining whether to command the user device may include receiving a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device, and deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold.

[0206] An indication of when the first timing advance value becomes invalid may include a timer value, and monitoring may include using the timer value to start the timer and determining in response to the timer's expiration that the first timing advance value is invalid or will soon become invalid.

[0207] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0208] Receiving configuration information may include receiving configuration information from a centralized unit.

[0209] According to the 38th aspect, a method is provided for a device for a first access node, the method comprising: establishing a connection to a user device via a serving cell supported by the first access node; receiving configuration information having at least one indication of the validity period of a timing advance value associated with a target cell supported by a second access node; instructing the user device to obtain a first timing advance value of the target cell, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; and monitoring the validity of the first timing advance value using its validity period.

[0210] The method may include determining that the monitoring indicates that a first timing advance value is invalid or will soon become invalid, and determining whether to instruct the user device to obtain a second timing advance value for the target cell in response to the determination that the first timing advance value is invalid or will soon become invalid, wherein the second timing advance value is obtained later in time than the first timing advance value.

[0211] Deciding whether to instruct the user device may include receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, and deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0212] Determining whether to command the user device may include receiving a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device, and deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold.

[0213] An indication of when the first timing advance value becomes invalid may include a timer value, and monitoring may include using the timer value to start the timer and determining that the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0214] The method may include receiving a first indication from the user device about the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0215] Receiving configuration information may include receiving configuration information from a centralized unit.

[0216] According to the 39th aspect, a device for a first access node is provided, the device comprising: an establishment circuit device for establishing a connection to a user device via a serving cell supported by the first access node; a receiving circuit device for receiving configuration information having at least one indication of the validity period of a timing advance value associated with a target cell supported by a second access node; an instruction circuit device for instructing the user device to obtain a first timing advance value of the target cell, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; and a monitoring circuit device for monitoring the validity of the first timing advance value using its validity period.

[0217] The device may include a decision circuit device for determining that the monitoring indicates that a first timing advance value is invalid or will soon become invalid, and a decision circuit device for determining whether to instruct a user device to acquire a second timing advance value for the target cell in response to the determination that the first timing advance value is invalid or will soon become invalid, wherein the second timing advance value is acquired later in time than the first timing advance value.

[0218] A decision circuit device for determining whether to command a user device may include a receiving circuit device for receiving a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device, and a decision circuit device for determining whether to command the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0219] A decision circuit device for determining whether to command a user device may include a receiving circuit device for receiving a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device, and a decision circuit device for determining whether to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold.

[0220] An indication of when the first timing advance value becomes invalid may include a timer value, and a monitoring circuit device for monitoring may include a start circuit device for starting the timer using the timer value, and a determination circuit device for determining whether the first timing advance value is invalid or will soon become invalid in response to the timer's expiration.

[0221] The device may include a receiving circuit device for receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0222] Receiving configuration information may include receiving configuration information from a centralized unit.

[0223] According to the 40th aspect, a non-temporary computer-readable medium is provided, comprising program instructions for causing a device for the first access node to perform the following actions: establish a connection to a user device via a serving cell supported by a first access node; receive configuration information having at least one indication of the validity period of a timing advance value associated with a target cell supported by a second access node; and instruct the user device to obtain a first timing advance value of the target cell, wherein the first timing advance value indicates the timing for sending an uplink transmission to the target cell; and monitor the validity of the first timing advance value using its validity period.

[0224] The device may be made to determine that the monitoring indicates that a first timing advance value is invalid or will soon become invalid, and to determine whether to instruct the user device to acquire a second timing advance value for the target cell in response to the determination that the first timing advance value is invalid or will soon become invalid, wherein the second timing advance value is acquired later in time than the first timing advance value.

[0225] Deciding whether to instruct the user device may include receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, and deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0226] Determining whether to command the user device may include receiving a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device, and deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold.

[0227] An indication of when the first timing advance value becomes invalid may include a timer value, and monitoring may include using the timer value to start the timer and determining in response to the timer's expiration that the first timing advance value is invalid or will soon become invalid.

[0228] The device may be configured to receive from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, the first indication being received in a Layer 1 measurement report.

[0229] Receiving configuration information may include receiving configuration information from a centralized unit.

[0230] According to the 41st aspect, a computer program product (e.g., software code) stored in a medium that can cause an apparatus to carry out any of the methods described herein is provided.

[0231] According to the 42nd aspect, an electronic device is provided that may be equipped with the apparatus described herein.

[0232] According to a 43rd aspect, a chipset is provided that can be equipped with the device described herein.

[0233] Some examples will be explained here for illustrative purposes only, with reference to the attached diagrams. [Brief explanation of the drawing]

[0234] [Figure 1] This is a schematic diagram of a 5G system. [Figure 2] This is a schematic diagram of the network device. [Figure 3] This is a schematic diagram of the user's equipment. [Figure 4] This is a diagram of signaling. [Figure 5] This is a diagram illustrating a real-world signaling example. [Figure 6] This is a diagram illustrating a real-world signaling example. [Figure 7] This is a diagram illustrating a real-world signaling example. [Figure 8] This is a diagram illustrating a real-world signaling example. [Figure 9] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 10] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 11] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 12] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 13] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 14] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 15] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Figure 16] This is a diagram illustrating the operation that can be performed by the apparatus described herein. [Modes for carrying out the invention]

[0235] The following describes possible actions that may be taken regarding timing advance, including those related to determining the validity of timing advance information.

[0236] The Timing Advance (TA) command allows the UE to adjust the uplink transmission of commands from the access node to the UE for reception by the access node.

[0237] For example, a network access node can constantly measure the time difference between the reception of uplink signals (e.g., physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), and / or sounding reference signal (SRS) reception) and the subframe time maintained by the network access node. Based on this measured time difference, the network access node can send a "timing advance" command to the UE, instructing it to change its transmission time so that it is better aligned with the subframe timing on the network side. If the uplink signal arrives at the network access node too early, the network access node can send a timing advance command to the UE, for example, "send your signal a little later." Similarly, if the uplink signal arrives at the network access node too late, the network access node can send a timing advance command to the UE, for example, "send your signal a little earlier."

[0238] Timing advance principles may also be provided to facilitate mobility operations (e.g., handover, cell addition, cell change, etc.). For example, a UE may be provided with a timing advance to apply to uplink transmissions made to a target cell in order to synchronize the UE's uplink transmission more quickly with the target cell's subframe timing. This may apply to intra-node handovers (e.g., when both the target cell and source cell are provided by the same network access node).

[0239] In the following explanation of the examples, specific embodiments are described with reference to devices capable of communication over wireless cellular systems, and to mobile communication systems serving such mobile communication devices. For brevity and clarity, such embodiments will be described with reference to 5G wireless communication systems. Nevertheless, it should be understood that such embodiments are not limited to 5G wireless communication systems and may apply to other wireless communication systems, for example, the current 6G proposal, IEEE 802.11, etc.

[0240] Before going into detail about the examples, the specific general principles of 5G wireless communication systems will be briefly explained with reference to Figures 1 through 3.

[0241] Figure 1 shows a schematic diagram of a 5G system (5GS) 100. The 5GS may comprise a user device (UE) 102 (also called a communication device or terminal), a 5G access network (AN) (which may be a 5G radio access network (RAN), or any other type of 5G AN such as a non-3GPP interworking function for untrusted / trusted non-3GPP access (N3IWF) / trusted non-3GPP gateway function (TNGF), or a wireline access gateway function for wireline access (W-AGF)) 104, a 5G core (5GC) 106, one or more application functions (AF) 108, and one or more data networks (DN) 110.

[0242] Figure 2 shows an example of a control unit for a communications system, which may be connected to and / or control, for example, access system stations such as base stations and RAN nodes such as gNBs, central units of the cloud architecture or nodes of the core network such as MMEs or S-GWs, scheduling entities such as spectrum management entities, or servers or hosts such as devices hosting NRFs, NWDAFs, AMFs, SMFs, UDMs / UDRs. The control unit may be integrated with the nodes or modules of the core network or RAN, or it may be located outside the nodes or modules. In some examples, the base station has a separate control unit or module. In other examples, the control unit may be another network element such as a radio network controller or spectrum controller. The control unit 200 may be arranged to control communications in the service area of ​​the system. The device 200 includes at least one memory 201, at least one data processing unit 202, 203, and an input / output interface 204. The control unit may be connected to the receivers and transmitters of the device via the interface. The receiver and / or transmitter may be implemented as a wireless front-end or remote wireless head. For example, the control unit 200 or processor 201 may be configured to execute appropriate software code to provide control functions. References to “code” herein are understood to mean software code, and vice versa.

[0243] Access system stations can be categorized into two different types: distributed units (DUs) and centralized units (CUs).

[0244] A DU provides access node support to the lower layers of the protocol stack (e.g., radio link control (RLC), medium access control (MAC), and / or the physical layer protocol layer). Each DU can support one or more cells, while each cell can support one or more beams.

[0245] A CU can support multiple DUs and provides access node support at higher layers of the protocol stack within the access node (e.g., Packet Data Convergence Protocol (PDCP), Service Data Adaptation Protocol (SDAP), and / or Radio Resource Control (RRC) protocol layer). The interface between the CU and DU is labeled as the F1 interface. Having a single CU per gNB, and a CU belonging to multiple gNBs, can be achieved using a shared hardware platform.

[0246] With reference to Figure 3, which shows a schematic partial cross-sectional view of communication device 300, possible wireless communication devices will be described in more detail from here on. Such communication devices are often referred to as user equipment (UE) or terminals. A suitable mobile communication device may be provided by any device that has the ability to send and receive radio signals. Non-limiting examples include mobile phones or "smartphones," computers provided with wireless interface cars or other wireless interface equipment (e.g., USB dongles), personal data assistants (PDAs) or tablets provided with wireless communication capabilities, or any combination thereof, or similar mobile stations (MS) or mobile devices. Mobile communication devices can provide data communication for carrying communications such as voice, email, text messages, and multimedia. Thus, users are presented with and provided with a number of services through their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communications or multimedia services, or simply access to data communications network systems such as the Internet. Users may also be provided with broadcast or multicast data. Non-limiting examples of content include downloads, television and wireless programs, videos, advertisements, various alerts, and other information.

[0247] Wireless communication devices may be, for example, mobile devices, i.e., devices not fixed to a specific location, or they may be stationary devices. Wireless devices may or may not require human interaction for communication. As described herein, the terms UE or “User” are used to refer to any type of wireless communication device.

[0248] The wireless device 300 can receive signals via air or a radio interface 307 through a suitable device for receiving radio signals, and can transmit signals through a suitable device for transmitting radio signals. In Figure 3, a transceiver device is schematically shown by block 306. The transceiver device 306 may be provided, for example, by a radio portion and an associated antenna array. The antenna array may be arranged inside or outside the wireless device.

[0249] The wireless device is typically provided with at least one data processing entity 301, at least one memory 302, and other possible components 303 for use in software code and hardware-assisted execution of tasks designed to perform, including control of access to and communication with access systems and other communication devices. Data processing, storage, and other related control devices can be provided on a suitable circuit board and / or chipset. This feature is represented by reference no. 304. The user can control the operation of the wireless device by a suitable user interface such as a keypad 305, voice commands, a touch-sensitive screen or pad, a combination thereof, or similar. A display 308, speaker, and microphone can also be provided. Furthermore, the wireless communication device may be equipped with suitable connectors (wired or wireless) for connecting to other devices and / or external accessories such as hands-free devices.

[0250] For clarity and brevity, certain terms used herein may be used interchangeably. For example, the terms "candidate cell," "target cell," and "candidate target cell" are used interchangeably herein. As another example, the terms "serving cell," "serving DU," "source cell," and "source DU" are used interchangeably herein. As yet another example, the terms "cell switch" and "handover" are used interchangeably herein.

[0251] In addition to existing mobility procedures, recent 3GPP considerations have taken into account Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedures. Layer 1 refers to the physical layer, and Layer 2 refers to the media access control (MAC) layer.

[0252] LTM is one of the objectives of the Mobility Enhancement Work Item in 3GPP Rel.18. LTM introduces a new technique aimed at reducing handover interrupt times. According to the LTM paradigm explanation, the determination of cell changes is based on L1 measurements and is performed at the MAC layer in the distributed unit (DU). This is in contrast to Layer 3 (L3) mobility procedures (e.g., network-triggered mobility procedures) where handovers between two cells are determined by the Radio Resource Control (RRC) layer.

[0253] 3GPP has recently considered the characteristics and considerations that will be established regarding the acquisition of early timing advance (TA) for candidate cell LTMs.

[0254] In particular, 3GPP has been investigating the provision of mechanisms and / or apparatus for the following: • Supports the acquisition of a candidate cell's TA (Terminal Adoption) before the cell switching command is received in L1 / L2-based mobility. The goal is to provide a mechanism for acquiring TA for candidate cells, with specific emphasis on the following: i. Random Access Channel (RACH) based mechanisms, such as Physical Downlink Control Channel (PDCCH) commanded RACH, UE-triggered RACH, and RACH triggered by the higher layer of the network (other than Layer 3 (Network Layer) handover commands). ii. RACH-less solutions, e.g., Sounding Reference Signal (SRS) based TA acquisition, Receive Timing Difference based RACH-less mechanisms (such as those in LTE), UE-based TA measurement (including UE-based TA measurement with a single Timing Advance Command (TAC) from the serving cell), etc. To provide a mechanism for obtaining a candidate cell TA that at least supports PDCCH-type RACH when the PDCHH directive is triggered only by the source cell. How such a form of RACH mechanism will be implemented (e.g., what downlink control information (DCI) will be provided, RACH resource allocation, etc.) is for future consideration.

[0255] TA updates for candidate cells (i.e., TA reacquisition) can be triggered by the network. The trigger mechanism can reuse the mechanism used for initial TA acquisition (e.g., PDCCH command-triggered RACH for candidate cells).

[0256] For PDCCH directive-type RACH in LTM, 3GPP is expected to support the indication of candidate cells and / or the provision of RACH occasions (ROs) for candidate cells within the DCI, and the provision of configuration of RACH resources for candidate cells before the transmission of the PDCCH directive.

[0257] 3GPP is further determining whether the transmission of a Random Access Response (RAR) to the RACH preamble transmission for PDCCH-directed RACH for candidate cells in LTM should be included. Three options are to always include the RAR, never include the RAR, or include the RAR depending on the dynamic configuration of the UE in a particular implementation.

[0258] Figure 4 illustrates a possible signaling example for a Long-Term Transfer (LTM) from a serving cell in the first distributed unit (DU1) to a target cell in the second distributed unit (DU2). This scenario is called an inter-DU intra-CU scenario. A similar signaling diagram is applied to an intra-DU intra-CU cell change, where DU1 is the same distributed unit as DU2.

[0259] Figure 4 illustrates signaling that may be carried out by UE401, source DU402 (e.g., the DU currently providing a serving cell to UE601), target DU403 (e.g., the handover candidate DU), and CU404 as part of an inter-DU LTM scenario.

[0260] Sections 4001-4012 relate to the mobility readiness stage.

[0261] Within 4001, UE401 signals the L3 measurement report to source DU402.

[0262] In 4002, source DU402 forwards the received L3 measurement report from 4001 to CU404. This signaling in 4002 can be performed using the uplink RRC message forwarding operation.

[0263] During 4003, CU404 determines, based on the received L3 measurement report, that another cell should be prepared to serve the UE, either in place of or in addition to the current serving cell provided by source DU402. Based on this decision, CU404 proceeds to set up the UE context for UE401 in target DU402 (during 4004-4005).

[0264] In 4004, CU404 signals target DU403. This signaling may include a UE context setup request operation to set up a UE context for UE401 in target DU402.

[0265] Within 4005, target DU403 signals CU404. This signaling can include a response to a UE context setup request.

[0266] In 4006, CU404 signals to source DU402. This signaling can request (if necessary) modification of the UE context stored in DU402 and / or provide information about the target cell. For example, this signaling can provide information about the target cell's reference signal configuration provided by target DU403, the target cell's transmit configuration index (TCI) status, etc. The signaling can include UE context modification request behavior.

[0267] Within 4007, source DU402 signals to CU404. This signaling may include a response to the signaling of 4006 to acknowledge receipt of the signaling of 4006. This signaling may include a UE context modification response behavior.

[0268] In 4008, CU404 generates an RRC reconfiguration for UE401.

[0269] This RRC reconstruction may involve reconfiguring the UE's current measurement configuration for performing L1 measurements. For example, this RRC reconstruction may involve a measurement configuration with L1 cell changes.

[0270] This RRC reconfiguration may include an indication of the configuration of the target cell prepared by the target DU403 during 4004-4005. For example, this RRC reconfiguration may include a timing advance (TA) acquisition configuration for when CU involvement will be used. The TA acquisition configuration may include at least one trigger condition that, when satisfied, causes a timing advance value to be acquired for the associated target cell. This can be useful, for example, in providing early timing information (timing advance) to the UE before any determination is made regarding a UE handover to the target cell. Since the timing information can be used to synchronize the UE's uplink transmit timing with the target cell's transmit timing before a potential handover, providing such timing information before a handover determination is made may result in a shorter interrupt time when the handover last occurred compared to when early timing advance information is not provided.

[0271] During 4009, CU404 signals to source DU402. This signaling may include RRC reconstruction generated during 4008. This signaling may include downlink RRC message transport operations.

[0272] During 4010, source DU402 forwards the received RRC reconstruction from 4009 to UE401.

[0273] During 4011, UE401 signals source DU402. This signaling may include an indication that the RRC reconstruction received during 4010 was performed by UE401. This signaling may include an RRC reconstruction completion action.

[0274] During 4012, source DU402 signals to CU404. This signaling can then forward the received RRC reconstruction completion indication from 4011 to CU404.

[0275] Sections 4013-4018 relate to the execution phase.

[0276] During 4013, UE401 provides the L1 measurement report to source DU402. The L1 measurement report contains values ​​representing the results of measurements performed by UE401 according to the RRC reconstruction received during 4010.

[0277] L1 measurement reports may be provided according to the RRC reconstructions received by the UE during 4010. L1 measurement reports may be provided periodically according to the RRC reconstructions received during 4010.

[0278] During 4014, based on the values ​​included in the L1 measurement report, source DU402 decides to trigger UE401 to acquire a TA for a set of candidate cells (e.g., candidate cells to become handover target cells). The UE may be triggered by source DU signaling to the UE using the Physical Downlink Control Channel (PDCCH).

[0279] In 4015, TA acquisition is performed by UE401. CU404 may be involved in this TA acquisition in some cases, however, it is understood that this is not necessary.

[0280] TA acquisition can be performed in any of a plurality of different ways depending on the configured implementation form and scenario. For example, TA can be determined using a reception timing difference-based mechanism, a random access channel-less mechanism (such as in LTE), a sounding reference signal (SRS)-based TA acquisition mechanism, etc. Which TA acquisition mechanism is implemented can be adjusted among the source DU, CU, and / or candidate target DUs during the LTM preparation phase (e.g., during 4004 - 4005).

[0281] During 4016, the UE signals an L1 measurement report to the source DU402 (e.g., according to 4013). In other words, the UE401 continues L1 measurement reporting according to the RRC reconfiguration received during 4010.

[0282] During 4017, based on the values included in the L1 measurement report received from the UE, the source DU402 determines that the UE401 should be handed over to another DU's cell (e.g., the target cell) (e.g., to the target DU403 in the current example).

[0283] During 4018, the source DU402 signals to the UE401 in response to the decision in 4017. This signaling in 4018 can trigger the UE401 to perform a cell switching (e.g., handover) operation. The signaling in 4018 can include, for example, a cell switching command (e.g., via a MAC control element). In one example, the cell switching command can also include the determined TA of the target cell.

[0284] 4019 - 4020 relate to the random access procedure for the UE401 to synchronize with the target DU403.

[0285] When 4019~4020 relate to a contention free random access procedure, the signaling can include that during 4019, UE401 signals a random access preamble to the target DU402, and during 4020, the target DU signals a random access response to this signaling of 4019.

[0286] When 4019~4020 relate to a contention based random access, in addition to signaling a preamble and receiving a response, the signaling can further include a contention resolution phase where UE401 signals an uplink during the uplink grant allocated in the random access response and receives a contention based response from the target DU.

[0287] 4019~4020 may not be implemented in some example implementations. For example, the UE can be configured not to perform a random access to the target cell when the UE has already acquired the TA of the target cell. <00009​​​​​​​​​Within 4022, target DU403 forwards the RRC reconfiguration completion indication from 4021 to CU404. The signaling of 4022 may include uplink RRC message forwarding signaling operation.

[0291] In 4023, CU404 signals source DU402. This signaling may include an instruction to source DU402 to release the UE context of UE401 from source DU402. This signaling in 4023 may include a UE context release command operation.

[0292] During 4024, source DU402 signals to CU404. This signaling in 4024 may occur when source DU402 releases the UE context of UE401. The signaling in 4024 may include a UE context release complete indicator to signal to CU404 that source DU402 has released the UE context of UE401.

[0293] During 4025, a route switching operation is performed to route traffic intended for UE401 to the target DU403 instead of the source DU402.

[0294] Part of the signaling in the above example in Figure 4 relates to maintaining uplink time matching.

[0295] For example, the 4010 RRC reconfiguration allows configuring a time alignment timer (TAT) in the UE for each timing advancement group (TAG). For instance, the TAT value controls how long the MAC entity in the UE considers the serving cell associated with this TAG, which will be time-aligned in the uplink.

[0296] Subsequently, when the timing advance command MAC control element is received, and NTA When an indicated TAG (such as the one defined in TS38.211) is maintained, the UE can apply timing advance commands for the indicated TAG and start or restart the timeAlignmentTimer associated with the indicated TAG. TA This parameter includes a value representing the timing advance between downlink and uplink transmissions.

[0297] Furthermore, when a timing advance command is received in a random access response message for a serving cell belonging to a TAG, or in an MSGB for a SpCell, and when a random access preamble is not selected by the MAC entity from among the conflict-based random access preambles, the UE can apply the timing advance command for this TAG and start or restart the timeAlignmentTimer associated with this TAG. An MSGB is a message used as part of a two-step random access procedure and is sent from the cell to the UE. An MSGB may contain a response to an MSGA (mentioned below), such as a random access response to a preamble contained in the MSGA. For example, an MSGB may contain the corresponding information and / or function as msg2 in a four-step random access procedure. An MSGB may contain conflict resolution information. For example, an MSGB may contain the corresponding information and / or function as msg4 in a four-step random access procedure.

[0298] Furthermore, when an absolute timing advance command is received in response to an MSGA transmission containing a Cell Radio Network Temporary Identifier (C-RNTI) MAC CE, the UE can apply a timing advance command for the Primary Timing Advance Group (PTAG) and start or restart the timeAlignmentTimer associated with the PTAG. An MSGA is a message used as part of a two-step random access procedure and is sent from the UE to the cell. An MSGA may contain a preamble for a random access procedure. For example, an MSGA may contain the corresponding information and / or function as msg1 in a four-step random access procedure. An MSGA may contain physical uplink shared channel information. For example, an MSGB may contain the corresponding information and / or function as msg3 in a four-step random access procedure.

[0299] When a timeAlignmentTimer expires, the UE can take different actions depending on whether the timeAlignmentTimer is associated with a PTAG or a Secondary Timing Access Group (STAG).

[0300] When a timeAlignmentTimer is associated with a PTAG, the UE can do the following: • Flushing all Hybrid Auto-Retransmission Request (HARQ) buffers (e.g., authorization buffers) for all serving cells. • When configured, notify the RRC to release the physical uplink control channel (PUCCH) for all serving cells. • If configured, notify the RRC to release the sounding reference signal for all serving cells. • Clear any configured downlink assignments and configured uplink grants. · Clear any PUSCH resources for semi-persistent CSI reporting, · Consider all running timeAlignmentTimers as expired, · Maintain the N of all TAGs TA when the timeAlignmentTimer is associated with the STAG, the UE can do the following.

[0301] · Flash all hybrid automatic repeat request (HARQ) buffers (e.g., grant buffers), · Notify the RRC to release the physical uplink control channel (PUCCH) for all serving cells when configured, · Notify the RRC to release the sounding reference signal for all serving cells when configured, · Clear any configured downlink allocations and configured uplink grants, · Clear any PUSCH resources for semi-persistent CSI reporting, and · Maintain the NTA of all TAGs. · Maintain the NTA of all TAGs.

[0302] According to the current Rel-18 3GPP consensus on early timing advance (TA) acquisition for L1 / 2 trigger-based mobility (LTM), the serving cell / DU can trigger the UE to update the TA for the candidate cell by reacquiring the TA using RACH-based procedures. <000097)0> Currently, there is no mechanism in the serving cell to determine when the serving cell should trigger TA reacquisition for another (e.g., non-co-located) cell.

[0304] <( After performing random access and acquiring a TA from the serving cell, the UE maintains the TAT for the serving cell. The UE can assume that the acquired TA remains valid as long as the TAT does not expire. If the UE does not receive a MAC command from the serving cell instructing it to update the TA before the TAT expires, the UE autonomously performs a random access procedure to the serving cell to synchronize with the serving cell in order to perform any further uplink transmissions (for example, when the UE has uplink traffic to transmit and the TAT expires).

[0305] In LTM, when the validity of acquired TA expires, the UE must implement a RACH base cell change, which delays the handover and renders early TA acquisitions unusable.

[0306] To address at least one of these problems, the following proposes a mechanism to enable the UE to maintain a valid TA value for the target cell.

[0307] In particular, the following describes a mechanism that may be applied when different devices are responsible for ensuring that the TA value of the target cell in the UE is valid.

[0308] For example, the following provides a mechanism for the target access node (e.g., target DU) to maintain a procedure for checking when the validity of the TA value provided to the UE for a candidate cell expires and triggers the reacquisition of the TA.

[0309] As another example, the following provides a mechanism for a source access node (e.g., source DU) to maintain a procedure for checking when the validity of the TA value provided to the UE for a candidate cell expires and triggers the reacquisition of the TA.

[0310] As another example, the following provides a mechanism for the UE to maintain a procedure for checking when the validity of the TA value provided to the UE for a candidate cell expires and triggers the reacquisition of the TA.

[0311] These are illustrated with regard to the signaling examples mentioned below in Figures 5 through 16.

[0312] In general, all of these diagrams illustrate an example where, after the initial TA value of a target cell is configured in the UE (for example, in response to determining that the target cell may soon (but not immediately) become the subject of a mobility action by the UE), at least one entity monitors the validity period of the initial TA value to trigger the UE to acquire a new TA value to replace the initial TA value when the validity period expires. The validity period is also referred to herein as the validity time.

[0313] In addition to determining whether to trigger the acquisition of a new / substitute TA value for the target cell based on this monitored validity period, the following also consider the use of a provided measurement report (e.g., L1 measurement report) to control whether the initial TA value should be replaced or simply released by the UE. This may be supplementary to monitoring the validity period.

[0314] After obtaining a new / substitute TA value, the UE can use this new / substitute TA value to synchronize with the target cell when a mobility action is performed (e.g., handover, cell change, and / or cell addition to the target cell). The UE can use the new / substitute TA value in this manner when the current measurement taken from the signal provided by the target cell triggers a mobility action to be performed (whether by command from the source node and / or autonomously by the UE for conditional mobility actions, etc.).

[0315] Figure 5 illustrates signaling that may be implemented in an example where the target DU maintains procedures to check the effectiveness of acquired TAs for candidate cells and to trigger TA reacquisition when desired.

[0316] Figure 5 illustrates signaling that can be implemented between UE501, the first DU502, CU503, and the second DU503. The first DU provides the first and second cells. The second DU provides the third cell.

[0317] During step 5001, UE501 establishes a connection to the first cell. This means that UE501 can receive data from the network via the first cell. From step 5001, the first cell is the current serving cell for UE501, and the first DU can be considered the source DU.

[0318] In 5002, UE501 signals the L3 measurement report to the first DU502. This may be as described above with respect to 4001.

[0319] In 5003, the first DU502 forwards the L3 measurement report of 5002 to CU503. This may be as described above with respect to 4002.

[0320] In 5004, the UE has an LTM configuration for the second and third cells. The second and third cells may be considered candidate target cells. Although not shown, this may be similar to those described above for 4003-4012.

[0321] During 5005, UE501 signals the L1 beam measurement to the first DU502. This can be done according to the RRC reconstruction signaled between 4003 and 4012.

[0322] In 5006, the first DU 502 signals to UE 501. This signaling may include an instruction to the UE to instruct the UE to take a timing advance for the third cell. Signaling of 5006 may be performed using a physical downlink control channel (PDCCH). Signaling of 5006 may be performed in response to received L1 beam measurements of 5005. For example, based on the received measurements of 5005, the first DU may determine that the third cell is a possible handover candidate for the UE in the near future and, in response to this decision, cause the UE to take a timing advance regarding the third cell. This process may also be called an early timing advance.

[0323] During 5007, UE501 performs a TA procedure to obtain the TA of the third cell. Any mechanism for obtaining the TA of the third cell may be used during 5007. Several example TA mechanisms are further mentioned below.

[0324] The second DU504 can send the TA associated with the third cell to the UE501 directly via the second DU504's radio link and / or indirectly via the first DU502.

[0325] In 5008, the second DU504 provides the timing advance value of the third cell to UE501 and then starts the execution of Timer T. Timer T may have a duration that represents the validity of the timing advance value. The expiration of Timer T may indicate that the timing advance value is no longer valid. The timer value may be set by the network configuration (for example, the network may configure the UE with a value that sets the timer duration).

[0326] During 5009, the second DU504 decides to trigger the source node to instruct the UE to reacquire the timing advance for the third cell. 5009 may be performed before or at the expiration of timer T.

[0327] In 5010, the second DU504 signals the first DU502. This signaling can indicate that the timing advance value of the third cell should be reacquired by UE501. In other words, this signaling can indicate that the timing advance value of the third cell is no longer valid. This signaling can be routed through CU503.

[0328] During 5011, UE signals the L1 beam measurement results to the first DU502.

[0329] During 5012, the first DU502 determines the current radio state of the third cell from the perspective of the UE based on the received L1 beam measurement. Depending on the current radio state of the third cell, the first DU502 may signal 5013 or 5014 to UE501.

[0330] 5013 may be performed when the current radio state of the third cell indicates that the third cell is a good handover candidate for UE501. During 5013, the first DU502 signals to UE501. The signaling of 5013 may include an instruction to the UE to instruct the UE to obtain a timing advance for the third cell. The signaling of 5013 may be signaled using PDCCH. Although not shown, the UE may return to 5007.

[0331] 5014 may be performed when the current radio state of the third cell indicates that the third cell is not a good handover candidate for UE501. In other words, 5014 may be performed when the first DU501 determines from at least one L1 measurement report received from the UE that the radio state of the third cell is no longer sufficient for the third cell to be a candidate cell (e.g., the third cell's L1 reference signal received power (RSRP) (or some corresponding metric) < a given threshold).

[0332] During 5014, the first DU502 signals UE501. The signaling in 5014 can instruct the UE to remove any previously stored TA values ​​from any of the third cells. Although not shown, UE501 can remove this previously stored TA value acquired during 5007. UE501 can continue to hold the third cell as a potential handover candidate while releasing the previously stored TA value.

[0333] In 5015, the first DU502 signals the second DU504. This signaling may constitute approval or negative approval of the signaling of 5013. Approval may indicate that when 5013 is signaled, the third cell provides a radio signal sufficient to obtain the TA value. Negative approval may indicate that when 5014 is signaled, the third cell does not provide a radio signal sufficient to obtain the TA value. Sufficient state of the radio signal (or the opposite) may be assessed with respect to the intensity and / or quality of the radio signal.

[0334] Figure 6 illustrates signaling that may be implemented in an example where the source DU maintains procedures to check the effectiveness of acquired TAs for candidate cells and to trigger TA reacquisition when desired.

[0335] Figure 6 illustrates signaling that can be implemented between UE601, the first DU602, CU603, and the second DU603. The first DU provides the first and second cells. The second DU provides the third cell. The first cell is the current serving cell of UE601.

[0336] During step 6001, UE601 establishes a connection to the first cell. This means that UE601 can receive data from the network via the first cell. From step 6001, the first cell is the current serving cell for UE601, and the first DU can be considered the source DU.

[0337] In 6002, UE601 signals the L3 measurement report to the first DU602. This may be as described above with respect to 4001.

[0338] In 6003, the first DU602 forwards the L3 measurement report of 6002 to CU603. This may be as described above with respect to 4002.

[0339] In 6004, the UE has an LTM configuration for the second and third cells. The second and third cells may be considered candidate target cells. Although not shown, this may be similar to those described above for 4003-4012.

[0340] During 6005, UE601 signals the L1 beam measurement to the first DU602. This can be done according to the RRC reconstruction signaled between 4003 and 4012.

[0341] In 6006, the first DU602 signals UE601. This signaling may include an instruction to the UE to instruct the UE to obtain a timing advance for the third cell. The signaling of 6006 may be signaled using a physical downlink control channel (PDCCH), which may be as described above with respect to Figure 5.

[0342] In 6007, UE601 performs the TA procedure to obtain the TA of the third cell.

[0343] The second DU604 can send the TA associated with the third cell to the UE601 directly via the radio link of the second DU604 and / or indirectly via the first DU602.

[0344] In 6008, the second DU604 signals the first DU602. This signaling may include an indication of when the timing advance value of the third cell should be reacquired by UE601. For example, this signaling may include an indication of the time value at which the timing advance value will be considered invalid.

[0345] In one example, the time duration value may be sent from the second DU to the first DU when the TA (e.g., in 6007) is delivered to the UE or the first cell. This signaling may be routed through CU603.

[0346] In one example, the time duration value may be sent from the second DU604 to the first DU601 while the third cell is being prepared as a candidate cell in the second DU. This signaling may be routed through CU603.

[0347] In one example, the time duration value is indicated by CU in the first DU602.

[0348] In 6009, the first DU602 runs a timer that indicates when the timing advance value of the third cell has expired or is about to expire.

[0349] During 6010, the UE signals the L1 beam measurement results to the first DU602.

[0350] During 6011, the first DU602 determines the current radio state of the third cell from the perspective of the UE based on the received L1 beam measurement. Depending on the current radio state of the third cell, the first DU602 may signal UE601 to 6012 or 6013 when the timer value indicates that the timing advance value of the third cell has expired or is about to expire.

[0351] 6012 may be performed when the current radio state of the third cell indicates that the third cell is a good handover candidate for UE601. During 6012, the first DU602 signals to UE601. The signaling of 6012 may include an instruction to the UE to instruct the UE to obtain a timing advance for the third cell. The signaling of 6012 may be signaled using PDCCH. Although not shown, the UE may return to 6007.

[0352] 6013 may be performed when the current radio state of the third cell indicates that the third cell is not a good handover candidate for UE601. In other words, 6013 may be performed when the first DU601 determines from at least one L1 measurement report received from the UE that the radio state of the third cell is no longer sufficient to make the third cell a candidate cell (e.g., the third cell's L1 reference signal received power (RSRP) (or some corresponding metric) < a given threshold).

[0353] In 6013, the first DU602 signals UE601. The signaling in 6013 can instruct the UE to remove any previously stored TA values ​​from any of the third cells. Although not shown, UE601 can remove this previously stored TA value acquired in 6007.

[0354] Figure 7 illustrates signaling that may be implemented in an example where the UE maintains procedures to check the effectiveness of acquired TAs for candidate cells and to trigger TA reacquisition when desired.

[0355] Figure 7 illustrates signaling that can be implemented between UE701, the first DU702, CU703, and the second DU703. The first DU provides the first and second cells. The second DU provides the third cell. The first cell is the current serving cell of UE701.

[0356] During step 7001, UE701 establishes a connection to the first cell. This means that UE701 can receive data from the network via the first cell. From step 7001, the first cell is the current serving cell for UE701, and the first DU can be considered the source DU.

[0357] In 7002, UE701 signals the L3 measurement report to the first DU702. This may be as described above with respect to 4001.

[0358] In 7003, the first DU702 forwards the L3 measurement report of 7002 to CU703. This may be as described above with respect to 4002.

[0359] In 7004, the UE has an LTM configuration for the second and third cells. The second and third cells may be considered candidate target cells. Although not shown, this may be similar to those described above for 4003-4012.

[0360] During 7005, UE701 signals the L1 beam measurement to the first DU702. This can be done according to the RRC reconstruction signaled between 4003 and 4012.

[0361] In 7006, the first DU702 signals UE701. This signaling may include an instruction to the UE to instruct the UE to obtain a timing advance for the third cell. The signaling of 7006 may be signaled using a physical downlink control channel (PDCCH). This signaling may be as described above with respect to Figure 5.

[0362] In 7007, UE701 performs the TA procedure to obtain the TA of the third cell.

[0363] The second DU704 can send the TA associated with the third cell to the UE701 directly via the second DU704's radio link and / or indirectly via the first DU702.

[0364] During 7008, UE801 executes a timer. The timer can be initialized to a time value at which the timing advance value will be considered invalid. Therefore, the timer can expire when the timing advance value is considered invalid.

[0365] In one example, the time duration value may be sent to the UE by a second DU when the TA (e.g., during 7007) is delivered to the UE or the first cell.

[0366] In one example, the time duration value may be sent to UE701 by the second DU704 while the third cell is being prepared as a candidate cell in UE701.

[0367] In one example, the time duration value is indicated to UE701 by CU.

[0368] During 7009, the UE determines that the timer has expired or is nearing its expiration.

[0369] In response to the decision in 7009, during 7010, the UE signals to the first DU702 that the timing advance value of the third cell is invalid.

[0370] During the 7011 process, UE701 signals the L1 beam measurement results to the first DU702.

[0371] In response to the signaling of 7010 and 7011, the first DU702 determines from the received L1 beam measurement what the current radio state of the third cell is from the perspective of the UE. Depending on the current radio state of the third cell, the first DU702 may signal 7013 or 7014 to UE701.

[0372] 7013 may be performed when the current radio state of the third cell indicates that the third cell is a good handover candidate for UE701. During 7013, the first DU702 signals to UE701. The signaling of 7013 may include an instruction to the UE to instruct the UE to obtain a timing advance for the third cell. The signaling of 7013 may be signaled using PDCCH. Although not shown, the UE may return to 7007.

[0373] 7014 may be performed when the current radio state of the third cell indicates that the third cell is not a good handover candidate for UE701. In other words, 7014 may be performed when the first DU701 determines from at least one L1 measurement report received from the UE that the radio state of the third cell is no longer sufficient for the third cell to be a candidate cell (e.g., the third cell's L1 reference signal received power (RSRP) (or some corresponding metric) < a given threshold).

[0374] During 7014, the first DU702 signals UE701. The signaling of 7014 can instruct the UE to remove any previously stored TA values ​​from any of the third cells. Although not shown, UE701 can remove this previously stored TA value acquired during 7007.

[0375] In this example in Figure 7, the UE informs the source DU that the acquired TA for a particular candidate cell has become invalid. The UE can receive a timer T with a duration T1 to maintain the validity of the acquired TA from the network. The duration T1 can be unique to each candidate cell. In other words, the duration T1 can be unique to each target cell. After acquiring the TA for a candidate (e.g., target) cell, the UE can start timer T with a duration T1.

[0376] The UE can acquire the TA of a candidate cell in response to a command from the network (for example, from the source DU) to do so.

[0377] The network can instruct the UE to acquire a TA when it determines that the UE is likely to perform a handover (or some other mobility procedure) to a candidate cell in the near future (for example, not immediately in response to acquiring a TA). The UE understands that it may or may not perform a handover (or some other mobility procedure) regarding the candidate cell, depending on subsequent measurements made by the UE of the signals transmitted by the candidate cell.

[0378] The UE can notify the source DU of the invalidation of the TA before / at the expiration of timer T. Using the received information, the serving DU can trigger the UE to either 1) reacquire the TA for the candidate cell controlled by the target DU providing the candidate cell, or 2) discard the TA acquired for the candidate cell.

[0379] Figure 8 illustrates signaling that may be implemented in an example where the UE maintains procedures to check the effectiveness of acquired TAs for candidate cells and to trigger TA reacquisition when desired.

[0380] Figure 8 illustrates signaling that can be implemented between UE801, the first DU802, CU803, and the second DU803. The first DU provides the first and second cells. The second DU provides the third cell. The first cell is the current serving cell of UE801.

[0381] Figure 8 illustrates signaling that may be implemented in an example where the UE maintains procedures to check the effectiveness of acquired TAs for candidate cells and to trigger TA reacquisition when desired.

[0382] Figure 8 illustrates signaling that can be implemented between UE801, the first DU802, CU803, and the second DU803. The first DU provides the first and second cells. The second DU provides the third cell. The first cell is the current serving cell of UE801.

[0383] During 8001, UE801 establishes a connection to the first cell. This means that UE801 can receive data from the network via the first cell. From 8001, the first cell is the current serving cell for UE801, and the first DU can be considered the source DU.

[0384] In 8002, UE801 signals the L3 measurement report to the first DU802. This may be as described above with respect to 4001.

[0385] In 8003, the first DU802 forwards the L3 measurement report of 8002 to CU803. This may be as described above for 4002.

[0386] In 8004, the UE has an LTM configuration for the second and third cells. The second and third cells may be considered candidate target cells. Although not shown, this may be similar to those described above for 4003-4012.

[0387] During 8005, UE801 signals the L1 beam measurement to the first DU802. This can be done according to the RRC reconstruction signaled between 4003 and 4012.

[0388] In 8006, the first DU802 signals to UE801. This signaling may include an instruction to the UE to instruct the UE to obtain a timing advance for the third cell. The signaling does not need to instruct the UE to obtain a timing advance for the second cell because the first DU802 provides the second cell and is aware of its timing. Signaling of 8006 may be signaled using a physical downlink control channel (PDCCH). This signaling may be as described above with respect to Figure 5.

[0389] In 8007, UE801 performs the TA procedure to obtain the TA of the third cell.

[0390] The second DU804 can send the TA associated with the third cell to the UE801 directly via the second DU804's radio link and / or indirectly via the first DU802.

[0391] During operation 8008, UE801 executes a timer. The timer can be initialized to a time value at which the timing advance value will be considered invalid. Therefore, the timer can expire when the timing advance value is considered invalid.

[0392] In one example, the value of the time duration may be sent to the UE by the second DU when the TA (e.g., in 8007) is delivered to the UE or the first cell.

[0393] In one example, the time duration value may be sent to UE801 by the second DU804 while the third cell is being prepared as a candidate cell in UE801.

[0394] In one example, the time duration value is indicated to UE801 by CU.

[0395] During 8009, the UE determines that the timer has expired or is nearing its expiration.

[0396] In response to the decision in 8009, in 8010, the UE determines from the beam measurements what the current radio state of the third cell is from the UE's perspective. The beam measurements may include L1 and / or L3 beam measurements. Depending on the current radio state of the third cell, the UE may perform 8011 or 8012.

[0397] 8011 may be performed when the current radio state of the third cell indicates that the third cell is a good handover candidate for UE801. During 8011, the UE autonomously initiates acquiring a new timing advance for the third cell.

[0398] In 8011, the UE can use the previously utilized TA mechanism to obtain a new timing advance for the third cell.

[0399] For example, when Contention-Free Random Access (CFRA) was performed to acquire a candidate cell's previous TA, UE801 can use the same RACH configuration (e.g., RA preamble, RACH occasion, etc.) during 8011. For example, a CFRA configuration used during 8007 to acquire a TA may also be used during 8011. This may be possible if the UE has similar radio conditions during 8011 as it did during 8007 (e.g., the same synchronous signal block (SSB) associated with the CFRA preamble is of sufficient quality (capable of being received with reference signal received power (RSRP) greater than the threshold amount).

[0400] Similarly, in another example, the UE can use a Contention-based Random Access (CBRA) configuration previously sent to the UE during candidate cell preparation to perform a CBRA for TA reacquisition.

[0401] 8012 may be performed when the current radio state of the third cell indicates that the third cell is not a good handover candidate for UE801. In other words, 8012 may be performed when the UE determines from at least one L1 measurement that the radio state of the third cell is no longer sufficient for the third cell to be a candidate cell (e.g., the third cell's L1 reference signal received power (RSRP) (or some corresponding metric) < a given threshold).

[0402] In 8012, UE removes any previously stored TA values ​​from any of the third cells.

[0403] The features of the examples described above are highlighted below with respect to Figures 9 to 16. Therefore, these highlighted features can be found to correspond to at least one of the examples provided above. Thus, the examples mentioned above may be combined with at least one of the following described below. While the following indicates that some devices are interacting, it should be noted that these devices are not limited to interacting with each other, and various other combinations of devices may also exchange signaling with each other.

[0404] Figures 9 and 10 illustrate features that can be implemented by interacting the devices.

[0405] Figure 9 illustrates the operations that can be performed by the first access node. The first access node may be an entity that provides access to the network to user equipment. The first access node may signal traffic to and / or from user equipment. The first access node may be a distributed unit. The first access node may be a gNB.

[0406] In 901, the first access node establishes a connection to user equipment via a serving cell supported by the first access node. The connection may include a user plane connection.

[0407] During 902, the first access node instructs the user device to obtain a first timing advance value for the target cell supported by the second access node, the first timing advance value indicating the timing for sending an uplink transmission to the target cell.

[0408] This command may be issued in response to the first access node determining that it may soon be useful for user equipment to perform cell mobility operations (e.g., handover, cell addition, and / or cell change operations) on the target cell. The determination that it may soon be useful for user equipment to perform cell mobility operations may depend on the receipt of a measurement report (e.g., an L1 measurement report) from user equipment that indicates that the signal quality and / or power of the target cell has reached a minimum threshold level.

[0409] The second access node may be a different access node from the first access node.

[0410] During 903, the first access node receives an indication from the second access node that the first timing advance value is invalid or will soon become invalid. This reception may occur after 902.

[0411] An indication can have an explicit indication that the first timing advance value is invalid or will soon become invalid. For example, an indication can have a field that can take one of two values, one of which indicates that the first timing advance value is invalid or will soon become invalid.

[0412] In 904, the first access node determines whether to instruct the user device to obtain a second timing advance value for the target cell, depending on the received indication, and the second timing advance value is obtained chronologically later than the first timing advance value.

[0413] The first access node may carry out any of the instructions according to the result of the decision in 904.

[0414] The first access node may receive a first indication from the user device regarding the current strength and / or quality of the signal from the target cell received by the user device. In such a case, deciding whether to instruct the user device may further include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0415] The first access node can receive a first indication from the user device regarding the current strength and / or quality of the signal from the target cell received by the user device. In such a case, deciding whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold. Commanding the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements (e.g., layer 1 measurements) on the signal provided by the target cell.

[0416] The first access node can receive the first indication in the Layer 1 measurement report from the user device.

[0417] An indication that the first timing advance value is no longer valid or will become invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0418] The first access node can signal a response to an indication that the first timing advance value is invalid or will soon become invalid. The response may include an indication of whether the user device has been instructed to reacquire the timing advance for the target cell.

[0419] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0420] The first access node may determine, from a second indication of the current intensity and / or quality of the target cell received from the user device (e.g., via an L1 measurement report), that the user device should be handed over to the target cell, and in response to this determination, the user device may be handed over to the target cell (or perform some other mobility action with respect to the target cell). The handover and / or mobility action may be performed using a second timing advance value.

[0421] Figure 10 illustrates an operation that may be performed by a second access node. The second access node may correspond to the second access node mentioned in relation to Figure 9. The second access node may be an entity that can provide access to the network to user equipment but has not yet established a connection with user equipment. The second access node may also be a target access node. The second access node may also be a distributed unit. The second access node may also be a gNB.

[0422] In 1001, the second access node ensures that the first timing advance value is provided to the user equipment in order to enable the user equipment to synchronize its uplink transmission to the timing of the target cell supported by the second access node. This can be done according to any method for providing the timing advance value to the user equipment.

[0423] In 1002, the second access node determines the validity period of the first timing advance value, and the first timing advance value is considered invalid after the validity period. The validity period may be pre-configured by the second access node before the first timing advance value is provided to the user equipment. The validity period may be determined when the first timing advance value is provided to the user equipment.

[0424] In 1003, the second access node signals to the first access node supporting the serving cell connected to the user equipment an indication that the first timing advance value is invalid or will soon be invalid before or at the expiration of the validity period. The first access node may be the first access node mentioned above with respect to Figure 9. The indication may consist of an explicit indication that the first timing advance value is invalid or will soon be invalid. For example, the indication may consist of a field that can take one of two values, where one value indicates that the first timing advance value is invalid or will soon be invalid.

[0425] The second access node may receive a response to an indication that the first timing advance value is invalid or will soon become invalid, and the response may include an indication that the user device has been instructed to reacquire the timing advance for the target cell.

[0426] The response may indicate that the user device has been instructed to reacquire the timing advance of the target cell, and the second access node may provide the user device with a second timing advance value to enable the user device to synchronize its uplink transmission to the timing of the target cell supported by the second access node. This second timing advance value may be provided to the user device in the same manner as the first timing advance value was provided to the user device.

[0427] Figures 11 and 12 illustrate another pair of interacting devices.

[0428] Figure 11 illustrates the operations that can be performed by the first access node. The first access node may be an entity that provides access to the network to user equipment. The first access node may signal traffic to and / or from user equipment. The first access node may be a distributed unit. The first access node may be a gNB.

[0429] In 1101, the first access node establishes a connection to user equipment via a serving cell supported by the first access node. The connection may include a user plane connection.

[0430] During 1102, the first access node instructs the user device to obtain a first timing advance value for the target cell supported by the second access node, the first timing advance value indicating the timing for sending an uplink transmission to the target cell.

[0431] This command may be issued in response to the first access node determining that it may soon be useful for user equipment to perform cell mobility operations (e.g., handover, cell addition, and / or cell change operations) on the target cell. The determination that it may soon be useful for user equipment to perform cell mobility operations may depend on the receipt of a measurement report (e.g., an L1 measurement report) from user equipment that indicates that the signal quality and / or power of the target cell has reached a minimum threshold level.

[0432] The second access node may be a different access node from the first access node.

[0433] During 1103, the first access node receives an indication from the second access node about when the first timing advance value will become invalid. This signaling in 1103 may be received after 1102.

[0434] During 1104, the first access node uses an indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid. The first access node may autonomously make the decision in 1104 using the information contained in the received indication.

[0435] During 1105, the first access node determines whether it should instruct the user device to obtain a second timing advance value for the target cell in response to the use, the second timing advance value being obtained later in time than the first timing advance value.

[0436] The first access node may carry out any of the instructions according to the result of the decision in 1105.

[0437] The first access node may receive a first indication from the user device regarding the current strength and / or quality of the signal from the target cell received by the user device. In such a case, deciding whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal provided by the target cell received by the user device has increased beyond a predetermined threshold.

[0438] The first access node can receive a first indication from the user device regarding the current strength and / or quality of the signal from the target cell received by the user device. In such a case, deciding whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the signal provided by the target cell received by the user device is below a predetermined threshold. Commanding the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements (e.g., layer 1 measurements) on the signal provided by the target cell.

[0439] The first access node can receive the first indication in the Layer 1 measurement report from the user device.

[0440] An indication of when the first timing advance value becomes invalid for user equipment to send an uplink to the target cell may be received indirectly from a second access node via a centralized unit.

[0441] An indication of when the first timing advance value will become invalid may include a timer value. In such a case, the first access node may use the timer value to start a timer (for example, by initializing a timer with a timer value such that the timer expires for a time duration corresponding to the timer value) and determine in response to the timer's expiration that the first timing advance value is invalid or will soon become invalid.

[0442] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0443] The first access node may determine, from a second indication of the current intensity and / or quality of the target cell received from the user device (e.g., via an L1 measurement report), that the user device should be handed over to the target cell, and in response to this determination, the user device may be handed over to the target cell (or perform some other mobility action with respect to the target cell). The handover and / or mobility action may be performed using a second timing advance value.

[0444] Figure 12 illustrates the operations that may be performed by the second access node. The second access node may correspond to the second access node mentioned in relation to Figure 11. The second access node may be an entity that can provide access to the network to user devices but has not yet established a connection with the user devices. The second access node may also be a target access node. The second access node may also be a distributed unit. The second access node may also be a gNB.

[0445] During 1201, the second access node ensures that the first timing advance value is provided to the user equipment in order to enable the user equipment to synchronize its uplink transmission to the timing of the target cell supported by the second access node. This can be done according to any method for providing the timing advance value to the user equipment.

[0446] In 1202, the second access node determines the validity period of the first timing advance value, and the first timing advance value is considered invalid after the validity period. The validity period may be pre-configured by the second access node before the first timing advance value is provided to the user equipment. The validity period may be determined when the first timing advance value is provided to the user equipment.

[0447] In 1203, the second access node signals the validity period to the first access node that supports the serving cell connected to the user equipment. This signaling in 1203 may explicitly include a value for the validity period. This validity period value may be expressed as an absolute time (e.g., with respect to Coordinated Universal Time). This validity period value may be expressed as a relative time (e.g., with respect to the time of transmission of the time value and / or with respect to the current Coordinated Universal Time).

[0448] Figures 13 and 14 illustrate another pair of interacting devices.

[0449] Figure 13 illustrates the operations that can be performed by the first access node. The first access node may be an entity that provides access to the network to user equipment. The first access node may signal traffic to and / or from user equipment. The first access node may be a distributed unit. The first access node may be a gNB.

[0450] In 1301, the first access node establishes a connection to user equipment via a serving cell supported by the first access node. The connection may include a user plane connection.

[0451] In 1302, the first access node instructs the user device to obtain a first timing advance value for the target cell supported by the second access node, the first timing advance value indicating the timing for sending an uplink transmission to the target cell.

[0452] This command may be issued in response to the first access node determining that it may soon be useful for user equipment to perform cell mobility operations (e.g., handover, cell addition, and / or cell change operations) on the target cell. The determination that it may soon be useful for user equipment to perform cell mobility operations may depend on the receipt of a measurement report (e.g., an L1 measurement report) from user equipment that indicates that the signal quality and / or power of the target cell has reached a minimum threshold level.

[0453] The second access node may be a different access node from the first access node.

[0454] During 1303, the first access node receives an indication from the user device that the first timing advance value is invalid or will soon be invalid. The indication may include an explicit indication that the first timing advance value is invalid or will soon be invalid. For example, the indication may include a field that can take one of two values, where one value indicates that the first timing advance value is invalid or will soon be invalid.

[0455] In 1304, the first access node determines whether to instruct the user device to obtain a second timing advance value for the target cell in response to the received indication, the second timing advance value being obtained later in time than the first timing advance value.

[0456] The first access node may carry out any of the instructions according to the result of the decision in 1304.

[0457] The first access node can receive a first indication from the user device regarding the current strength and / or quality of the signal of the target cell received by the user device. In such a case, deciding whether to instruct the user device may include deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0458] The first access node can receive a first indication from the user device regarding the current strength and / or quality of the signal from the target cell received by the user device. In such a case, deciding whether to command the user device may include deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the signal from the target cell received by the user device is below a predetermined threshold. Commanding the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements (e.g., layer 1 measurements) on the signal provided by the target cell.

[0459] A first indication of the current intensity and / or quality of the signal from the target cell may be received in the Layer 1 measurement report.

[0460] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0461] The first access node may determine, from a second indication of the current intensity and / or quality of the target cell received from the user device (e.g., via an L1 measurement report), that the user device should be handed over to the target cell, and in response to this determination, the user device may be handed over to the target cell (or perform some other mobility action with respect to the target cell). The handover and / or mobility action may be performed using a second timing advance value.

[0462] Figure 14 illustrates an operation that may be performed by a device for user equipment. User equipment may be the user equipment mentioned above with respect to Figure 13.

[0463] During 1401, the user device may obtain a first timing advance value for a target cell supported by the second access node, the first timing advance value indicating the timing for sending an uplink transmission to the target cell. This acquisition may be performed in response to the first access node instructing the user device to obtain the first timing advance value. Any mechanism for obtaining the timing advance value of a cell may be used by the user device to obtain the first timing advance value.

[0464] During 1402, the user device receives an indication of when the first timing advance value will become invalid.

[0465] During 1403, the user device uses an indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid.

[0466] During 1404, the user device signals to the serving cell supported by the first access node that, in response to the use, the first timing advance value is invalid or will soon be invalid.

[0467] The user device can signal a first indication to the serving cell about the current strength and / or quality of the signal from the target cell received by the user device, the first indication being received by the user device and signaled in the Layer 1 measurement report.

[0468] An indication of when the first timing advance value will become invalid may include a timer value. In such a case, the user device can use the timer value to start the timer (for example, by initializing the timer with a timer value such that the timer expires for a time duration corresponding to the timer value), and in response to the timer's expiration, it can determine that the first timing advance value is invalid or will soon become invalid.

[0469] An indication of when the first timing advance value becomes invalid may be obtained before the first timing advance value is acquired. For example, an indication of when the first timing advance value becomes invalid may be provided in a configuration for mobility triggered at a lower tier (e.g., in an LLM configuration). An indication of when the first timing value becomes invalid may be obtained when the first timing advance value is acquired.

[0470] The user device can receive a command from the serving cell to acquire a second timing advance value and, in response to the command, acquire the second timing advance value, which is acquired chronologically later than the first timing advance value. The second timing advance value may be acquired using the same mechanism used to acquire the first timing advance value.

[0471] The user device can receive a command from the serving cell to release the first timing advance value and can release the first timing advance value in response to this command. Thus, the command can cause the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements (e.g., layer 1 measurements) on the signal provided by the target cell.

[0472] Figure 15 illustrates the operations that can be performed by a real-world user device.

[0473] During 1501, the user device may obtain a first timing advance value for a target cell supported by the second access node, the first timing advance value indicating the timing for sending an uplink transmission to the target cell. This acquisition may be performed in response to the first access node instructing the user device to obtain the first timing advance value. Any mechanism for obtaining the timing advance value of a cell may be used by the user device to obtain the first timing advance value.

[0474] During 1502, the user device receives an indication of when the first timing advance value will become invalid.

[0475] During 1503, the user device uses an indication of when the first timing advance value will become invalid to determine that the first timing advance value is invalid or will soon become invalid.

[0476] In 1504, the user device decides whether to autonomously begin acquiring a second timing advance value for the target cell, depending on whether the first timing advance value is invalid or will soon become invalid, and the second timing advance value is acquired later in time than the first timing advance value.

[0477] The user device can be configured to implement the 1504 decision. For example, the user device can autonomously initiate the acquisition of a second time value when it is determined that the first timing advance value is valid or will soon be valid.

[0478] The decision of whether to autonomously initiate the acquisition of a second timing absentee value may further depend on the current intensity and / or quality of the signal from the target cell received by the user equipment. The current intensity and / or quality may be measured by the user equipment. The current intensity and / or quality may be measured (and / or reported to the first access node) according to the LLM configuration applied in the user equipment.

[0479] An indication of when the first timing advance value will become invalid may include a timer value. In such a case, the user device can use the timer value to start the timer (for example, by initializing the timer with a timer value such that the timer expires for a time duration corresponding to the timer value), and in response to the timer's expiration, it can determine that the first timing advance value is invalid or will soon become invalid.

[0480] An indication of when the first timing advance value becomes invalid may be obtained before the first timing advance value is acquired. For example, an indication of when the first timing advance value becomes invalid may be provided in a configuration for mobility triggered at a lower tier (e.g., in an LLM configuration). An indication of when the first timing value becomes invalid may be obtained when the first timing advance value is acquired. An indication of when the first timing advance value becomes invalid may be provided in a configuration for mobility triggered at a lower tier.

[0481] The user device may decide to autonomously begin acquiring a second timing advance value for the target cell when it determines that the first timing advance value is invalid or will soon become invalid, and may acquire the second timing advance value in response to this decision to autonomously begin acquiring it. The second timing advance value may be acquired using the same mechanism used to acquire the first timing advance value.

[0482] The user device can decide not to acquire a second timing advance value for the target cell when the current intensity and / or quality of the signal provided by the target cell is below a predetermined threshold, and in response to this decision not to acquire the second timing advance value, it can release the first timing advance value. Thus, this decision allows the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements (e.g., layer 1 measurements) on the signal provided by the target cell.

[0483] The decision of whether to autonomously initiate the acquisition of a second timing advance value for the target cell may further depend on whether the user device has received a command from the serving cell to release the first timing advance value. For example, the user device may refrain from autonomously initiating the acquisition of a second timing advance value when it receives such a command. This command may further cause the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements on the signal provided by the target cell (e.g., layer 1 measurements).

[0484] Figure 16 illustrates the operations that may be performed by the device for the first access node. The first access node may be an entity that provides access to the network to user equipment. The first access node may signal traffic to and / or from user equipment. The first access node may be a distributed unit. The first access node may be a gNB.

[0485] In 1601, the first access node establishes a connection to the user equipment via a serving cell supported by the first access node. In other words, the first access node can support a serving node that serves the user equipment.

[0486] During 1602, the first access node receives configuration information that includes at least one indication of the validity period of the timing advance value associated with the target cell supported by the second access node.

[0487] During 1603, the first access node can instruct the user device to obtain a first timing advance value for the target cell, which indicates the timing for sending an uplink transmission to the target cell.

[0488] During 1604, the first access node monitors the validity of the first timing advance value using the lifetime.

[0489] The first access node may determine that the monitoring indicates that the first timing advance value is invalid or will soon become invalid. In response to the determination that the first timing advance value is invalid or will soon become invalid, the first access node may determine whether to instruct the user device to obtain a second timing advance value for the target cell, the second timing advance value being obtained in a later time than the first timing advance value. The first access node may trigger a determination as to whether to instruct the user device.

[0490] Deciding whether to instruct the user device may include receiving a first indication from the user device about the current strength and / or quality of the signal of the target cell received by the user device, and deciding to instruct the user device to obtain a second timing advance value when the first indication indicates that the current strength and / or quality of the signal of the target cell received by the user device has increased beyond a predetermined threshold.

[0491] Deciding whether to command the user device may include receiving a first indication from the user device about the current strength and / or quality of the signal from the target cell received by the user device, and deciding to command the user device to release a first timing advance value when the first indication indicates that the current strength and / or quality of the target cell received by the user device is below a predetermined threshold. Commanding the user device to release the first timing advance level while continuing to perform (and report to the first access node) measurements (e.g., layer 1 measurements) on the signal provided by the target cell.

[0492] The first indication may be included in the Layer 1 measurement report.

[0493] An indication of when the first timing advance value will become invalid may include a timer value. In such a case, the first access node may use the timer value to start a timer (for example, by initializing a timer with a timer value such that the timer expires for a time duration corresponding to the timer value) and determine in response to the timer's expiration that the first timing advance value is invalid or will soon become invalid.

[0494] Commanding the user device to acquire a first timing advance value may be performed in response to receiving a Layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

[0495] The first access node may determine, from a second indication of the current intensity and / or quality of the target cell received from the user device (e.g., via an L1 measurement report), that the user device should be handed over to the target cell, and in response to this determination, the user device may be handed over to the target cell (or perform some other mobility action with respect to the target cell). The handover and / or mobility action may be performed using a second timing advance value.

[0496] Receiving configuration information may include receiving configuration information from a centralized unit. Configuration information may be received when LTM is configured on the user equipment (for example, when a Layer 1 measurement reporting configuration is configured on the user equipment).

[0497] The mechanism currently described can allow the UE to reacquire the TA of a candidate cell before a potential handover to that candidate cell. For example, the mechanism currently described can allow the network to trigger the UE in a timely manner to reacquire the TA of a candidate cell. The technique currently described can reduce the possibility of fallback to RACH resulting from an invalid / outdated TA of a candidate cell, making the process more efficient.

[0498] The above references to the first network node, first access node, first network access node, serving access node, source access node, serving DU, source DU, and similar entities are understood to be used without distinction. These entities may have the capability to support at least one cell that facilitates the transport of traffic between user equipment and the network. The first network node may be implemented, for example, as a network node that supports the distributed unit DU function and / or Layer 2 protocol processing of a radio access network RAN, source DU, serving DU, serving gNB, 5G gNB, NR gNB, and / or base station, presenting broad applicability to different RAN implementation forms.

[0499] The above references to a second network node, second access node, second network access node, target access node, target DU, and similar entities are understood to be used without distinction. These entities may have the capability to support at least one cell that facilitates the transfer of traffic between user equipment and the network. A second network node may be implemented, for example, as a network node supporting the distributed unit DU functionality and / or Layer 2 protocol processing of a radio access network RAN, target DU, target gNB, 5G gNB, NR gNB, and / or base station, which also provides broad applicability to different RAN implementation forms. The first and second network nodes may be the same as different nodes.

[0500] The third network node may be implemented, for example, as a network node supporting radio access network RAN, CU, source CU, serving CU, source gNB, 5G gNB, NR gNB, and / or base station central unit CU functions and / or layer 3 protocol processing. The third network node can control the first network node and / or the second network node. The first and second network nodes may be controlled by the same third network node or by different third network nodes.

[0501] User devices can be implemented, for example, as devices or equipment that support Layer 2 and Layer 3 protocol processing in wireless access networks (RANs), smartphones, and / or mobile terminals.

[0502] To carry out the method, the UE and / or access node may have specific means for performing specific functions / tasks. For example, to carry out one or more of the method steps listed above, the UE and / or access node may include establishment means, receiving means, determination means, acquisition means, transmission means, and / or monitoring means, and / or the access node may include establishment means, receiving means, determination means, transmission means, and / or monitoring means. The specific means may be carried out using hardware and / or software, such as specific circuit equipment and / or specific computer program code.

[0503] The user device may comprise at least some of the components mentioned above with respect to Figure 3. In addition to the at least one processor and at least one memory containing computer code mentioned above, the user device may comprise, for example, at least one of a transceiver, transmitter, receiver, antenna, radio frequency front end, and / or baseband processor.

[0504] The foregoing explanation has provided a complete and useful description of some examples, but only as non-limiting examples. Nevertheless, when read together with the accompanying drawings and claims, various modifications and adaptations may become apparent to those skilled in the art in consideration of the foregoing explanation. Nevertheless, all such and similar modifications of the teachings remain within the scope of the claims.

[0505] The above describes various examples of access architectures to which the techniques described may be applied, using radio access architectures based on Long-Term Evolution Advanced (LTE Advanced, LTE-A) or New Radio (NR, 5G), but without limiting the examples to such architectures. The examples may also be applied to other types of communication networks with appropriate means by appropriately adjusting the parameters and procedures. Some examples of other options for suitable systems include Universal Mobile Telecommunications System (UMTS) radio access networks (UTRAN), wireless local area networks (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth®, Personal Communication Services (PCS), ZigBee®, Broadband Code Division Multiple Access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad hoc networks (MANET), and Internet Protocol Multimedia Subsystem (IMS), or any combination thereof.

[0506] Various embodiments are described in the detailed description of the examples and in the claims, as provided herein. In general, some examples may be implemented in hardware or special-purpose circuits, software code, logic, or a combination thereof. For example, some embodiments may be implemented in hardware, while others may be implemented in firmware or software code that can be executed by a controller, microprocessor, or other computing device, but the examples are not limited to these. Various examples may be illustrated and described using block diagrams, flowcharts, or other certain graphical representations, but it should be understood that these blocks, apparatus, systems, techniques, or methods described herein may, in non-limiting examples, be implemented in hardware, software code, firmware code, special-purpose circuits or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0507] The example may be stored in memory and implemented by computer software code that can be executed by at least one data processor of the involved entities, or by hardware, or by a combination of software code and hardware.

[0508] The memories referred to herein may be of any type appropriate to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

[0509] The (data) processors referred to herein may be of any type appropriate to the local technical environment and may include, in non-limiting examples, one or more of the following: general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), FPGAs, gate-level circuits, and processors based on multicore processor architectures.

[0510] Furthermore, it should be noted that, in this regard, any procedure, such as those shown in Figure 9, and / or Figure 10, and / or Figure 11, and / or Figure 12, and / or Figure 13, and / or Figure 14, and / or Figure 15, and / or Figure 16, and / or otherwise previously described, may represent a computer program deployed by at least one processor included in the device (the computer program comprises instructions for causing the device to perform at least one action, and the instructions are represented as software code stored in at least one memory), or the operation of interconnected logic circuits, blocks, and functions, or a combination of the operation of a computer program deployed by at least one processor included in the device and logic circuits, blocks, and functions. The software code may be stored in physical media such as memory chips, or memory such as memory blocks implemented in the processor, magnetic media (such as hard disks or floppy disks), and optical media (such as DVDs and their data variants, CDs, etc.).

[0511] Memory may be of any type appropriate to the local technical environment and can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processor may be of any type appropriate to the local technical environment and may, in non-limiting examples, include one or more of the following: general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), gate-level circuits, and processors based on multi-core processor architectures.

[0512] As an addition or alternative, some examples may be implemented using circuitry and / or means. The circuitry and / or means may be configured to perform one or more of the previously described functional and / or method steps. This circuitry and / or means may be provided in access nodes and / or communication devices and / or core network entities and / or user equipment.

[0513] As used in this application, the terms “circuit equipment” and / or “means” are: (a) Hardware-only circuit implementation configurations (such as implementation configurations consisting only of analog and / or digital circuit equipment), (b) (i) combinations of software / firmware code and analog and / or digital hardware circuits, (ii) Any part of a hardware processor, software code, and memory that work together to enable a device such as a communication device or base station to perform the various functions previously described, including a digital signal processor, software code, and memory. Combinations of hardware circuits and software code, (c) Hardware circuits and / or processors, such as a microprocessor or a part of a microprocessor, that require software code (e.g., firmware) for operation but may not be present when the software code is not needed for operation. It can refer to one, more, or all of the above.

[0514] This definition of circuit equipment and / or means applies to all uses of the term in this application, including any claim. Further examples include, as used in this application, the term circuit equipment and / or means also covers implementations of a hardware circuit or processor (or a number of processors) or a portion of a hardware circuit or processor, and their (or their) accompanying software and / or firmware code. The term circuit equipment and / or means also covers, for example, integrated devices.

[0515] The implementations of this disclosure can be carried out in various components, such as integrated circuit modules. Designing integrated circuits is generally a highly automated process. Complex and powerful software tools are available to convert logic-level designs into ready-to-etch and formed semiconductor circuit designs on semiconductor substrates.

[0516] As used herein, "at least one of the following: <list of two or more elements>" and "at least one of the <list of two or more elements>" and similar wording mean, when the lists of two or more elements are connected by "and" or "or", at least one of the elements, or at least two or more of the elements, or at least all of the elements.

[0517] The term "non-transient" as used herein refers to a limitation of the medium itself (i.e., tangible, not signal-based) as opposed to a limitation of the persistence of data storage (e.g., RAM vs. ROM).

[0518] The scope of protection required for the various examples of this disclosure is described by the independent claims. Any examples and features described herein that are not included in the scope of the independent claims will be construed as useful examples for understanding this disclosure.

[0519] The foregoing description has provided a complete and useful description of the implementations of the examples of this disclosure as non-limiting examples. Nevertheless, when read together with the accompanying drawings and the accompanying claims, various modifications and adaptations may become apparent to those skilled in the art in consideration of the foregoing description. Nevertheless, all such and similar modifications of the teachings of this disclosure still fall within the scope of the invention as defined in the accompanying claims. In practice, there are further implementations comprising combinations of one or more implementations with any of the other implementations discussed previously.

Claims

1. A device for a first access node, comprising at least one processor and at least one memory, when executed by the at least one processor, Establishing a connection to user equipment via a serving cell supported by the first access node, Commanding the user device to obtain a first timing advance value of a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell. Receiving an indication from the second access node regarding when the first timing advance value will become invalid, To determine whether the first timing advance value is invalid or will soon become invalid, use the indication of when the first timing advance value will become invalid, and Determining whether to instruct the user device to obtain a second timing advance value of the target cell in response to the aforementioned use, wherein the second timing advance value is obtained later in time than the first timing advance value. A device comprising at least one memory containing code that causes the device to perform the following.

2. Supporting the reception from the user device of a first indication of the current strength and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device to do so, When the first indication indicates that the current intensity and / or quality of the signal provided by the target cell, received by the user device, has increased beyond a predetermined threshold, it is decided to instruct the user device to obtain the second timing advance value. The apparatus according to claim 1, including the following:

3. This includes supporting receiving from the user device a first indication of the current strength and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device to do so. When the first indication indicates that the current intensity and / or quality of the signal provided by the target cell, received by the user device, is below a predetermined threshold, it is determined to command the user device to release the first timing advance value. The apparatus according to claim 1, including the following:

4. The apparatus according to claim 1, wherein the indication of when the first timing advance value becomes invalid for the user device to transmit an uplink to the target cell is received indirectly from the second access node via a centralized unit.

5. The indication of when the first timing advance value becomes invalid includes a timer value, and the device, The timer is started using the aforementioned timer value, In response to the expiration of the timer, it is determined that the first timing advance value is invalid or will soon become invalid. The apparatus according to claim 1, comprising means for carrying out the action.

6. The apparatus according to claim 1, wherein the apparatus supports receiving from the user equipment a first indication of the current intensity and / or quality of the signal of the target cell received by the user equipment, the first indication being received in a layer 1 measurement report.

7. The apparatus according to claim 1, wherein the command to the user device to acquire the first timing advance value is performed in response to receiving a layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

8. A device for a second access node, comprising at least one processor and at least one memory, when executed by the at least one processor, To enable the user device to synchronize its uplink transmission with the timing of the target cell supported by the second access node, a first timing advance value is provided to the user device. Determining the effective time of the first timing advance value, which is determined to be invalid after the effective time, and Signaling the effective time to the first access node that supports the serving cell connected to the user device. A device comprising at least one memory containing code that causes the device to perform the following.

9. A method for a device for a first access node, The steps include establishing a connection to a user device via a serving cell supported by the first access node, Steps include instructing the user device to obtain a first timing advance value for a target cell supported by a second access node, wherein the first timing advance value indicates a timing for sending an uplink transmission to the target cell; The steps include receiving an indication from the second access node regarding when the first timing advance value will become invalid, The steps include using the indication of when the first timing advance value will become invalid in order to determine whether the first timing advance value is invalid or will soon become invalid, A step of determining whether to instruct the user device to obtain a second timing advance value of the target cell in response to the step of using the above, wherein the second timing advance value is obtained later in time than the first timing advance value. Methods that include...

10. The step of receiving from the user device a first indication from the user device of the current strength and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device, The step of deciding to instruct the user device to obtain the second timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell, as received by the user device, has increased beyond a predetermined threshold. The method according to claim 9, including the method described in claim 9.

11. The step of receiving from the user device a first indication from the user device of the current strength and / or quality of the signal of the target cell received by the user device, and determining whether to instruct the user device, Steps to determine to command the user device to release the first timing advance value when the first indication indicates that the current intensity and / or quality of the signal provided by the target cell, as received by the user device, is below a predetermined threshold. The method according to claim 9, including the method described in claim 9.

12. The method according to claim 9, wherein the indication of when the first timing advance value becomes invalid for the user device to transmit an uplink to the target cell is received indirectly from the second access node via a centralized unit.

13. The indication of when the first timing advance value becomes invalid includes a timer value, and the method is The steps include starting the timer using the aforementioned timer value, A step of determining that the first timing advance value is invalid or will soon become invalid in response to the expiration of the timer; The method according to claim 9, including the method described in claim 9.

14. The method according to claim 9, comprising the step of receiving from the user device a first indication of the current intensity and / or quality of the signal of the target cell received by the user device, wherein the first indication is received in a layer 1 measurement report.

15. The method according to claim 9, wherein the step of commanding the user device to obtain the first timing advance value is performed in response to receiving a layer 1 measurement report from the user device indicating that the intensity and / or quality of the signal provided by the target cell exceeds a pre-configured threshold.

16. A memory storing computer-readable instructions for causing a device to carry out the method described in claim 9.

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