Conditional Handover (CHO) Deconfiguration and Fault Handling in Wireless Communications

Abstract

To provide conditional handover (CHO) deconfiguration and failure handling in wireless communications.SOLUTION: Methods, systems, and devices for wireless communications are described for management of conditional handover (CHO) configurations. A source base station may configure user equipment (UE) with one or more CHO configurations for multiple target base stations. The CHO configurations may provide, for each target base station, one or more associated conditions that may trigger the UE to initiate a handover to a particular target base station, or to deconfigure a CHO configuration, such as based on a measurement threshold of one or more target base station measurements, one or more source base station measurements, or combinations thereof. The CHO configurations may also include failure handling information for initiating one or more subsequent handovers responsive to a failure of an initial handover attempt.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Cross-reference This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 842,330, filed May 2, 2019, by Purkayastha et al. and titled "Conditional Handover (CHO) Deconfiguration and Failure Handling in Wireless Communications", and U.S. Patent Application No. 16 / 805,347, filed Feb. 28, 2020, by Purkayastha et al. and titled "Conditional Handover (CHO) Deconfiguration and Failure Handling in Wireless Communications", each of which is assigned to the assignee of this application.

[0002] The following generally relates to wireless communications and, more particularly, to conditional handover (CHO) deconfiguration and failure handling in wireless communications.

Background Art

[0003] Wireless communication systems are widely deployed to provide various types of communication content, including voice, video, packet data, messaging, and broadcast. These systems may support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth-generation (4G) systems such as Long-Term Evolution (LTE) systems, LTE-A systems, or LTE-A Pro systems, and fifth-generation (5G) systems, sometimes referred to as New Radio (NR) systems. These systems may employ technologies such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include several base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may sometimes be referred to as user equipment (UEs).

[0004] In some cases, a UE may be moving to one or more base stations, which may result in the UE undergoing a handover procedure from the base station to which it is currently connected (e.g., the source base station) to a new base station (e.g., the target base station). The handover procedure may be initiated by the exchange of information related to the UE between the source and target base stations, and by the source base station sending a handover command to the UE. In some cases, the UE may reduce its connection to the source base station and initiate a random access procedure with the target base station to establish a connection with it. In some cases, one or more handover configurations may be provided to the UE before it initiates a handover, and the UE may initiate a handover when it detects conditions indicated in the configuration; such handovers are sometimes called conditional handovers (CHOs). However, conditional handover configurations present challenges related to managing CHO configurations for target base stations. [Overview of the project] [Means for solving the problem]

[0005] The techniques described relate to improved methods, systems, devices, and apparatus for supporting conditional handover (CHO) deconfiguration and fault handling in wireless communications. Various aspects of this disclosure describe techniques for managing CHO configurations. In some cases, a source base station may configure user equipment (UE) with one or more CHO configurations for multiple target base stations. A CHO configuration may provide one or more relevant conditions for each target base station that can trigger the UE to initiate a handover to a particular target base station (for example, based on measurement thresholds for one or more target base station measurements, one or more source base station measurements, or a combination thereof). In some cases, a CHO configuration may include fault handling information, deconfiguration criteria, or a combination thereof.

[0006] In some cases, fault handling information may include one or more CHO timer values, and when a random access request is sent to the target base station, the UE may activate the CHO timer associated with the target base station. If the UE and the target base station cannot complete the random access procedure before the CHO timer expires, the UE may identify that the handover to the target base station failed. In some cases, in response to fault identification, the UE may determine whether any other target base stations have a CHO configuration, and if a CHO configuration exists for the second base station, it may send a random access request to the second target base station. The UE may repeat the handover attempts and fault identification until the handover is successful or until there are no more additional target base stations with a CHO configuration, at which point the UE may declare a radio link failure and activate the re-establishment procedure.

[0007] In some cases, one or more CHO configurations may include deconfiguration criteria. In such cases, the UE may perform one or more measurements (e.g., signal strength measurements or channel quality measurements) on the source base station, one or more target base stations, or a combination thereof. If one or more of the measurements of a particular target base station satisfy the deconfiguration criteria, the UE may deconfigure the CHO configuration associated with that particular target base station. In some cases, the UE may send a measurement report to the source base station that may include measurements associated with the target base station being deconfigured, which the source base station may use to release the handover configuration. In some cases, the UE may send a deconfiguration instruction with a measurement report (e.g., the cell ID of the target base station being deconfigured).

[0008] A method for wireless communication in a UE is described. The method may include receiving a conditional handover configuration from a source base station indicating one or more target base stations, one or more measurement thresholds for initiating a handover from a source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; determining, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met; sending a first random access request to the first target base station based on the conditional handover configuration in order to initiate a first random access procedure for the handover to the first target base station; starting a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request; and determining a first conditional handover failure in response to the expiration of the first conditional handover timer before the completion of the first random access procedure.

[0009] A device for wireless communication in a UE is described. The device may include a processor, memory communicating electronically with the processor, and instructions stored in the memory. Instructions may be executable by the processor to cause the device to receive a conditional handover configuration from a source base station indicating one or more target base stations, one or more measurement thresholds for initiating a handover from a source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; to determine, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met; to send a first random access request to the first target base station based on the conditional handover configuration in order to initiate a first random access procedure for the handover to the first target base station; to start a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request; and to determine a first conditional handover failure in response to the expiration of the first conditional handover timer before the completion of the first random access procedure.

[0010] Another apparatus for wireless communications in a UE is described. The apparatus may include means for receiving a conditional handover configuration from a source base station indicating one or more target base stations, one or more measurement thresholds for initiating a handover from a source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; determining, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met; transmitting a first random access request to the first target base station based on the conditional handover configuration in order to invoke a first random access procedure for the handover to the first target base station; starting a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request; and determining a first conditional handover failure in response to the expiration of the first conditional handover timer before the completion of the first random access procedure.

[0011] A non-temporary, computer-readable medium for storing code for wireless communications in a UE is described. The code may include instructions executable by a processor to: receive a conditional handover configuration from a source base station indicating one or more target base stations, one or more measurement thresholds for initiating a handover from a source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; determine, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met; send a first random access request to the first target base station based on the conditional handover configuration in order to initiate a first random access procedure for the handover to the first target base station; start a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request; and determine a first conditional handover failure in response to the expiration of the first conditional handover timer before the completion of the first random access procedure.

[0012] In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, one or more timers include at least a first conditional handover timer for completing a first random access procedure with a first target base station. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the conditional handover configuration includes at least a first conditional handover configuration for a first target base station and a second conditional handover configuration for a second target base station.

[0013] Some examples of methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for determining that a second measurement threshold is met to initiate a handover to a second target base station in response to the expiration of a first conditional handover timer; sending a second random access request to the second target base station based on a conditional handover configuration to initiate a second random access procedure for a handover to the second target base station; starting a second conditional handover timer to complete the second random access procedure; and repeating determining, transmitting, and initiating for any other target base stations configured for conditional handover in the event of further conditional handover failures. Some examples of methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for initiating a connection re-establishment procedure when it is determined that no other target base stations are configured for conditional handover.

[0014] In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the first duration of the first conditional handover timer may differ from the second duration of the second conditional handover timer. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the operations, features, means, or instructions for selecting a second target base station from a set of available target base stations based on channel quality measurements associated with each of the set of available target base stations, or any combination thereof, in response to the expiration of the first conditional handover timer.

[0015] Some examples of the methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for receiving a deconfiguration message from a source base station that deconfigures one or more conditional handover configurations, and for deconfiguring one or more conditional handover configurations based at least in part on the deconfiguration message. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the deconfiguration message is received from a source base station in radio resource control signaling. Some examples of the methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for deleting one or more of the radio resource control configurations, or first measurements, and reporting configurations for a conditional handover trigger provided in a first conditional handover configuration, and for ceasing the evaluation of a conditional handover measurement associated with the conditional handover configuration, and whether the measurement satisfies the conditional handover criteria.

[0016] A method for wireless communication in a UE is described. The method involves receiving a conditional handover configuration from a source base station that indicates one or more conditional handover configurations associated with one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; determining, based on the conditional handover configuration, that a first deconfiguration measurement threshold for deconfiguring a first conditional handover configuration of a first target base station is met; and releasing the first conditional handover configuration of the first target base station.

[0017] A device for wireless communication in a UE is described. The device may include a processor, memory communicating electronically with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the device to receive a conditional handover configuration from a source base station indicating one or more conditional handover configurations relating to one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; to determine on the conditional handover configuration that a first deconfiguration measurement threshold for deconfiguring the first conditional handover configuration of the first target base station is met; and to release the first conditional handover configuration of the first target base station.

[0018] Another apparatus for wireless communications in a UE is described. The apparatus receives from a source base station a conditional handover configuration indicating one or more conditional handover configurations associated with one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; and means for determining, based on the conditional handover configuration, that a first deconfiguration measurement threshold for deconfiguring a first conditional handover configuration of a first target base station is met; and releasing the first conditional handover configuration of the first target base station.

[0019] A non-temporary, computer-readable medium for storing code for wireless communications in a UE is described. The code includes receiving a conditional handover configuration from a source base station indicating one or more conditional handover configurations associated with one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; determining, based on the conditional handover configuration, that a first deconfiguration measurement threshold for deconfiguring a first conditional handover configuration of a first target base station is met; and releasing the first conditional handover configuration of the first target base station.

[0020] Some examples of methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for determining, based on a conditional handover configuration, that a second trigger measurement threshold for initiating a handover to a second target base station is met, and for sending a random access request to the second target base station based on a second conditional handover configuration of the second target base station in order to initiate a random access procedure for the handover to the second target base station.

[0021] In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, releasing a first conditional handover configuration may include an operation, feature, means, or instruction to remove one or more of the radio resource control configurations, first measurements, and reporting configurations for a conditional handover trigger and a conditional handover deconfiguration trigger provided within the first conditional handover configuration, or one or more timers associated with a first target base station, and to discontinue the evaluation of the conditional handover measurement associated with the first target base station and whether the measurement satisfies a conditional handover criterion or a conditional handover deconfiguration criterion.

[0022] Some examples of the methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for transmitting a measurement report to a source base station indicating that a first conditional handover configuration of a first target base station is released. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the measurement report includes a deconfiguration instruction for the first target base station.

[0023] In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the first deconfiguration measurement threshold may be a channel quality threshold related to a first target base station, where the first conditional handover configuration is released in response to the channel quality measurement of the first target base station being less than the channel quality threshold. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the first deconfiguration measurement threshold includes a first threshold related to a source base station and a second threshold related to a first target base station, where the first conditional handover configuration is released in response to the first channel quality measurement of the source base station being greater than the first threshold and the second channel quality measurement of the first target base station being less than the second threshold. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the first deconfiguration measurement threshold may be a differential threshold, where the first conditional handover configuration is released in response to the difference in channel quality measurements between a source base station and a first target base station exceeding a differential threshold.

[0024] A method for wireless communication at a source base station is described. The method involves the source base station establishing one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a conditional handover time period for completing a random access procedure when a conditional handover of a UE from the source base station to each target base station is initiated, and transmitting one or more conditional handover configurations to the UE, each indicating the relevant target base station, one or more measurement thresholds for initiating a handover of a UE from the source base station to the relevant target base station, and the conditional handover time period of the relevant target base station.

[0025] An apparatus for wireless communication at a source base station is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions may cause the apparatus to establish, by the source base station, one or more conditional handover configurations with respective target base stations for conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a conditional handover time period for completing a random access procedure upon activation of the conditional handover of the UE from the source base station to the respective target base station, and transmit, to the UE, one or more conditional handover configurations each indicating a related target base station, one or more measurement thresholds for initiating handover of the UE from the source base station to the related target base station, and the conditional handover time period of the related target base station, which may be executable by the processor.

[0026] Another apparatus for wireless communication at a source base station is described. The apparatus may include means for establishing, by the source base station, one or more conditional handover configurations with respective target base stations for conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a conditional handover time period for completing a random access procedure upon activation of the conditional handover of the UE from the source base station to the respective target base station, and transmitting, to the UE, one or more conditional handover configurations each indicating a related target base station, one or more measurement thresholds for initiating handover of the UE from the source base station to the related target base station, and the conditional handover time period of the related target base station.

[0027] A non - transitory computer - readable medium storing code for wireless communication in a source base station is described. The code is for the conditional handover of a UE from the source base station to one or more target base stations, and involves establishing, by the source base station, one or more conditional handover configurations with each of the target base stations. Here, each conditional handover configuration includes a conditional handover time period for completing a random access procedure upon activation of the conditional handover of the UE from the source base station to the respective target base station, one or more measurement thresholds for activating the handover of the UE from the source base station to the associated target base station, and the conditional handover time period of the associated target base station, and may include instructions executable by a processor to transmit the one or more conditional handover configurations, each indicating the above, to the UE.

[0028] In some examples of the methods, apparatuses, and non - transitory computer - readable media described herein, each of the one or more target base stations may have a different value for the conditional handover time period. In some examples of the methods, apparatuses, and non - transitory computer - readable media described herein, the conditional handover time period may be determined based on one or more of an estimated value of the movement of the UE with respect to each respective target base station, the traffic load of the source base station or each respective target base station, the channel quality measurement values for each respective target base station provided by the UE, or any combination thereof.

[0029] A method for wireless communication at a source base station is described. The method involves the source base station establishing one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; and transmitting one or more conditional handover configurations to the UE, each indicating a trigger measurement threshold for initiating a conditional handover to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station.

[0030] A device for wireless communication at a source base station is described. The device may include a processor, memory communicating electronically with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the device to establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; and to transmit one or more conditional handover configurations to the UE, each indicating a trigger measurement threshold for initiating a conditional handover to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station.

[0031] Another device for wireless communication at a source base station is described. The device may include means for the source base station to establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; and means for transmitting one or more conditional handover configurations to the UE, each indicating a trigger measurement threshold for initiating a conditional handover to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station.

[0032] A non-temporary computer-readable medium for storing code for wireless communication at a source base station is described. The code may include instructions executable by a processor to establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station; and to transmit one or more conditional handover configurations to the UE, each indicating a trigger measurement threshold for initiating a conditional handover to the associated target base station, a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station.

[0033] Some examples of methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for determining in a UE that at least one first conditional handover configuration should be deconfigured, transmitting deconfiguration information to the UE indicating that, in response to the decision to deconfigure, one or more of the radio resource control configuration, or first measurement, and reporting configurations for the first conditional handover configuration should be removed, and releasing the first conditional handover configuration of a first target base station.

[0034] Some examples of the methods, apparatus, and non-temporary computer-readable media described herein may further include operations, features, means, or instructions for receiving a measurement report from a UE indicating that a first deconfiguration measurement threshold for deconfiguring a first conditional handover configuration of a first target base station is met, and for releasing the first conditional handover configuration of the first target base station in response to the measurement report. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, releasing the first conditional handover configuration may include operations, features, means, or instructions for removing one or more of the radio resource control configuration, the first deconfiguration measurement threshold, the first trigger measurement threshold, or one or more timers associated with the first target base station that are included in the first conditional handover configuration.

[0035] In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, releasing a first conditional handover configuration may further include an operation, feature, means, or instruction for providing a first target base station with an instruction that the first conditional handover configuration is being released.

[0036] In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the deconfiguration measurement threshold may be a channel quality threshold associated with each respective target base station, where the conditional handover configuration of the first target base station is released in response that the channel quality measurement of the first target base station is less than the channel quality threshold of the first target base station. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the deconfiguration measurement threshold includes a first threshold associated with a source base station and a second threshold for each respective target base station, where the conditional handover configuration of the first target base station is released in response that the first channel quality measurement of the source base station exceeds the first threshold and the second channel quality measurement of the first target base station is less than the second threshold of the first target base station. In some examples of the methods, apparatus, and non-temporary computer-readable media described herein, the deconfiguration measurement threshold may be a differential threshold, where a conditional handover configuration associated with a first target base station is released in response to the difference in channel quality measurements between the source base station and the first target base station exceeding a differential threshold. [Brief explanation of the drawing]

[0037] [Figure 1] This figure shows an example of a system for wireless communications that supports conditional handover (CHO) deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 2] This figure shows an example of a part of a wireless communication system having a source base station and a target base station that supports CHO deconfiguration and fault handling in wireless communication according to the aspects of this disclosure. [Figure 3] This figure shows an exemplary process flow supporting CHO deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 4]This figure shows an exemplary process flow supporting CHO deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 5] This figure shows an exemplary process flow supporting CHO deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 6] This figure shows an exemplary process flow supporting CHO deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 7] This figure shows an exemplary process flow supporting CHO deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 8] This is a block diagram of a device that supports CHO configuration deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 9] This is a block diagram of a device that supports CHO configuration deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 10] This is a block diagram of a communications manager that supports CHO configuration deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 11] This is a diagram of a system including a device that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. [Figure 12] This is a block diagram of a device that supports CHO configuration deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 13] This is a block diagram of a device that supports CHO configuration deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 14] This is a block diagram of a communications manager that supports CHO configuration deconfiguration and fault handling in wireless communications according to the embodiments of this disclosure. [Figure 15] This is a diagram of a system including a device that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. [Figure 16] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 17] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 18] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 19] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 20] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 21] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Figure 22] This flowchart shows a method for supporting CHO configuration deconfiguration and fault handling in wireless communications according to the aspects of this disclosure. [Modes for carrying out the invention]

[0038] Various aspects of this disclosure provide techniques for user equipment (UE) handover in wireless communication systems. A UE may undergo a source cell-to-target cell handover procedure in which the UE may release or reduce its existing connection with a source cell in order to establish a new connection with a target cell. The handover procedure may be initiated by the exchange of information related to the UE between the source base station and the target base station, and by the source base station sending a handover command to the UE. In some cases, upon receiving the handover command, the UE may reduce its existing connection with the source base station and initiate a random access procedure with the target base station to establish a connection with the target base station. In some cases, one or more handover configurations may be provided to the UE before the UE initiates a handover, and the UE may initiate a handover when it detects conditions indicated in the configuration, such a handover may be called a conditional handover (CHO).

[0039] In some aspects of this disclosure, a source base station may configure a UE using one or more CHO configurations for a plurality of target base stations. A CHO configuration may provide, for each target base station, one or more associated conditions that can trigger the UE to initiate a handover to a particular target base station (for example, based on measurement thresholds for one or more target base station measurements, one or more source base station measurements, or a combination thereof), and one or more associated conditions for deconfiguring the CHO configuration. In some cases, a CHO configuration may include fault handling information, deconfiguration criteria, or a combination thereof.

[0040] In some cases, a CHO configuration may provide one or more handover criteria for one or more target base stations. The UE may perform one or more measurements of a target base station, a source base station, or a combination thereof, and if those measurements satisfy a handover criterion, the UE may initiate a handover with the target base station that satisfies the handover criterion (for example, by sending a random access request to the target base station). If the handover criterion is satisfied (for example, if the source base station measurement is below a threshold and the target base station measurement is above a threshold), the CHO configuration may allow the UE to autonomously initiate a handover; however, maintaining such a configuration may consume resources at the base station and the UE, may restrict the flexibility of one or more target base stations, and may consume overhead associated with target base station measurements.

[0041] For example, a source base station may constitute a CHO with a first target base station, which may result in the source base station periodically providing the first target base station with information related to the UE, the first target base station ensuring a non-conflicting random access preamble for the UE (which may restrict the first target base station from allocating the non-conflicting preamble to other devices), the UE performing measurements against the first target base station, and the UE transmitting measurement reports with measurements from the first target base station. Therefore, if the first target base station is no longer a suitable candidate for UE handover, deconfiguring the CHO of the first target base station may be beneficial to the UE, the source base station, and the target base station. Furthermore, if a random access procedure initiated as part of the CHO fails or there is a radio link failure, service interruption or increased latency may occur.

[0042] In some cases, according to the various techniques described herein, one or more CHO configurations may include deconfiguration criteria. In such cases, the UE may perform one or more measurements (e.g., signal strength measurements or channel quality measurements) on the source base station, one or more target base stations, or a combination thereof. If one or more of the measurements of the first target base station satisfy the deconfiguration criteria, the UE may deconfigure the CHO configuration associated with the first target base station. In some cases, the UE may autonomously deconfigure the CHO configuration. In some cases, the UE may send a measurement report to the source base station that may include measurements associated with the first target base station being deconfigured, which the source base station may use to release the handover configuration. In some cases, the UE may send a deconfiguration instruction with a measurement report (e.g., the cell ID of the target base station being deconfigured). In other cases, the UE may maintain the CHO configuration until the source base station sends a deconfiguration to the UE in response to the measurement report. The source base station may also provide a cancellation instruction to the first target base station, thereby allowing the first target base station to release the resources reserved for the UE.

[0043] In addition or alternatively, the CHO configuration may include one or more CHO timer values, and when a random access request is sent to the target base station, the UE may activate the CHO timer associated with the target base station. If the UE and the target base station cannot complete the random access procedure before the CHO timer expires, the UE may identify that the handover to the target base station failed. In some cases, in response to the failure identification, the UE may determine whether any other target base stations have a CHO configuration, and if a CHO configuration exists for the second base station, it may send a random access request to the second target base station. The UE may repeat the handover attempts and failure identification until the handover is successful or until there are no more additional target base stations with CHO configurations, at which point the UE may declare a radio link failure and activate the re-establish connection procedure.

[0044] Such techniques may enable efficient management and fault handling of CHO configurations in the event of a failed CHO handover. Deconfiguration of CHO configurations may enable more efficient management of CHO configurations by deconfiguring them based on UE measurements, thereby ensuring that a relatively recent set of CHO configurations can be used for the handover if the handover criteria are met. Furthermore, the fault handling techniques described herein may reduce latency and service interruptions associated with failed random access procedures in handover attempts.

[0045] The aspects of this disclosure are first described in the context of a wireless communication system. Subsequently, various exemplary process flows illustrating CHO configuration management and fault handling are described. The aspects of this disclosure are further illustrated and described with reference to device diagrams, system diagrams, and flowcharts relating to CHO deconfiguration and fault handling in wireless communications.

[0046] Figure 1 shows an example of a wireless communication system 100 that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long-Term Evolution (LTE) network, an LTE Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some cases, the wireless communication system 100 may support extended broadband communications, ultra-high reliability (e.g., mission-critical) communications, low-latency communications, or communications with low-cost, low-complexity devices.

[0047] Base station 105 may communicate wirelessly with UE 115 via one or more base station antennas. The base station 105 described herein may include, or may be referred to by, several other preferred terms, transceiver base station, radio base station, access point, radio transceiver, node B, enode B (eNB), next-generation node B or giganode B (either of which may be called gNB), home node B, home enode B, or several other preferred terms. The wireless communication system 100 may include different types of base stations 105 (e.g., macro base stations or small cell base stations). UE 115 described herein may communicate with various types of base stations 105 and network equipment, including macro eNBs, small cell eNBs, gNBs, relay base stations, etc.

[0048] Each base station 105 may be associated with a specific geographical coverage area 110 that supports communication with various UEs 115. Each base station 105 may provide communication coverage to its respective geographical coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the UEs 115 may utilize one or more carriers. The communication link 125 shown in the wireless communication system 100 may include uplink transmissions from the UEs 115 to the base station 105, or downlink transmissions from the base station 105 to the UEs 115. Downlink transmissions are sometimes called forward link transmissions, and uplink transmissions are sometimes called reverse link transmissions.

[0049] The geographical coverage area 110 for base station 105 may be divided into sectors that constitute a portion of the geographical coverage area 110, each sector may be associated with a cell. For example, each base station 105 may provide communication coverage to macrocells, small cells, hotspots, or other types of cells, or various combinations thereof. In some examples, base station 105 may be mobile and therefore may provide communication coverage to a moving geographical coverage area 110. In some examples, different geographical coverage areas 110 associated with different technologies may overlap, and overlapping geographical coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communication system 100 may include, for example, heterogeneous LTE / LTE-A / LTE-A Pro or NR networks in which different types of base stations 105 provide coverage to various geographical coverage areas 110.

[0050] The term “cell” refers to a logical communication entity used for communication with a base station 105 (for example, via a carrier) and may relate to identifiers (e.g., physical cell identifier (PCID), virtual cell identifier (VCID)) used to distinguish adjacent cells operating via the same or different carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communications (MTC), narrowband Internet of Things (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of devices. In some cases, the term “cell” may refer to a portion of a geographical coverage area 110 (e.g., a sector) on which a logical entity operates.

[0051] UE115 may be distributed throughout the entire wireless communication system 100, and each UE115 may be fixed or mobile. UE115 may also be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or several other preferred terms, where “device” may also be referred to as a unit, station, terminal, or client. UE115 may also be a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, UE115 may also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, any Internet of Things (IoE) device, or MTC device, which may be implemented in various items such as appliances, vehicles, meters, etc.

[0052] Some UE115s, such as MTC devices or IoT devices, may be low-cost or low-complexity devices that can provide automated communication between machines (for example, via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that enables devices to communicate with each other or with base stations 105 without human intervention. In some examples, M2M communication or MTC may include communication from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program where that information is available, or present that information to a human interacting with the program or application. Some UE115s may be designed to collect information or enable automated machine behavior. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0053] Some UE115s may be configured to employ power-saving operating modes, such as half-duplex communication (e.g., modes that support unidirectional communication via transmit or receive, but not simultaneous transmit and receive). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power-saving techniques for the UE115 include entering a power-saving "deep sleep" mode when not engaged in active communication, or operating over a limited bandwidth (e.g., according to narrowband communication). In some cases, the UE115 may be designed to support critical functions (e.g., mission-critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communication for these functions.

[0054] In some cases, UE115 may also be able to communicate directly with other UE115s (for example, using peer-to-peer (P2P) or device-to-device (D2D) protocols). One or more of the groups of UE115s utilizing D2D communication may be within the geographical coverage area 110 of base station 105. Other UE115s in such groups may be outside the geographical coverage area 110 of base station 105, or in some cases may not be able to receive transmissions from base station 105. In some cases, a group of UE115s communicating via D2D communication may utilize a one-to-many (1:M) system where each UE115 transmits to all other UE115s in the group. In some cases, base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between UE115s without the involvement of base station 105.

[0055] The base stations 105 can communicate with and with the core network 130. For example, a base station 105 can interface with the core network 130 via a backhaul link 132 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 can communicate with each other via a backhaul link 134 (e.g., via X2, Xn, or other interfaces), either directly (e.g., directly between base stations 105) or indirectly (e.g., via the core network 130).

[0056] The core network 130 may provide user authentication, access permission, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an advanced packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME may manage non-access layer (e.g., control plane) functions such as mobility, authentication, and bearer management for UE 115 serviced by base station 105 associated with the EPC. User IP packets may be forwarded through an S-GW which may itself be connected to a P-GW. The P-GW may provide IP address allocation and other functions. The P-GW may be connected to network operator IP services. Operator IP services may include access to the Internet, intranet, IP multimedia subsystem (IMS), or packet-switched (PS) streaming services.

[0057] At least some of the network devices, such as the base station 105, may include sub-components such as access network entities, which may be examples of access node controllers (ANCs). Each access network entity may communicate with the UE 115 through several other access network transmission entities, which may be called radio heads, smart radio heads, or transmit / receive points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or integrated into a single network device (e.g., base station 105).

[0058] The wireless communication system 100 may typically operate using one or more frequency bands within the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is called the ultra-high frequency (UHF) region or decimeter band, as the wavelengths range from approximately 1 decimeter to 1 meter. UHF waves may be blocked or redirected by building and environmental characteristics. However, the waves may penetrate structures well enough for a macrocell to service a UE 115 located indoors. Transmitting UHF waves may involve smaller antennas and shorter distances (e.g., less than 100 km) compared to transmitting using lower frequencies and longer waves in the shortwave (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0059] The wireless communication system 100 may also operate in the very high frequency (SHF) region, using a frequency band from 3 GHz to 30 GHz, also known as the centimeter band. The SHF region includes bands such as the 5 GHz industrial, scientific, and medical (ISM) band, which may be opportunistically used by devices that may be able to tolerate interference from other users.

[0060] The wireless communication system 100 may also operate in the extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz), also known as the millimeter band. In some examples, the wireless communication system 100 may support millimeter-wave (mmW) communication between a UE 115 and a base station 105, where the EHF antennas of each device may be even smaller and more densely spaced than UHF antennas. In some cases, this may facilitate the use of antenna arrays within the UE 115. However, propagation of EHF transmissions may be subject to greater atmospheric attenuation and shorter distances than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency domains, and the specified use of bands across these frequency domains may vary by country or regulatory body.

[0061] In some cases, the wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in unlicensed bands such as the 5GHz ISM band. When operating in unlicensed radio frequency spectrum bands, wireless devices such as base stations 105 and UE 115 may employ listen-before-talk (LBT) procedures to ensure that the frequency channel is clear before transmitting data. In some cases, operation in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in licensed bands (e.g., LAA). Operation in unlicensed spectrum may include downlink transmission, uplink transmission, peer-to-peer transmission, or a combination thereof. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.

[0062] In some examples, a base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. For example, a wireless communication system 100 may use a certain transmission scheme between a transmitting device (e.g., base station 105) and a receiving device (e.g., UE 115), where the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communication may employ multipath signal propagation to improve spectral efficiency by transmitting or receiving multiple signals over different spatial layers, which may be called spatial multiplexing. Multiple signals may be transmitted by the transmitting device over different antennas or different combinations of antennas. Similarly, multiple signals may be received by the receiving device over different antennas or different combinations of antennas. Each of the multiple signals may be called a separate spatial stream and may carry bits related to the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be related to different antenna ports used for channel measurement and channel reporting. MIMO techniques include single-user MIMO (SU-MIMO), in which multiple spatial layers are sent to the same receiving device, and multi-user MIMO (MU-MIMO), in which multiple spatial layers are sent to multiple devices.

[0063] Beamforming, sometimes called spatial filtering, directional transmission, or directional reception, is a signal processing technique that can be used in a transmitting or receiving device (e.g., base station 105 or UE115) to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming can be achieved by combining signals communicated through the antenna elements of an antenna array such that signals propagating in a particular orientation relative to the antenna array undergo constructive interference, while other signals undergo destructive interference. The coordination of signals communicated through antenna elements may include the transmitting or receiving device applying some amplitude and phase offset to the signals carried through each of the antenna elements associated with the device. The coordination associated with each antenna element may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device, or to some other orientation).

[0064] In one example, base station 105 may use multiple antennas or antenna arrays to guide beamforming operations for directional communication with UE 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by base station 105 in different directions, which may include the signals being transmitted according to different beamforming weight sets associated with the different directions of transmission. Transmissions in different beam directions may be used to identify the beam direction for subsequent transmissions and / or receptions by base station 105 (e.g., by base station 105 or a receiving device such as UE 115).

[0065] In some cases, the antennas of base station 105 or UE 115 may be located within one or more antenna arrays that can support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be located together in an antenna assembly such as an antenna tower. In some cases, the antennas or antenna arrays associated with base station 105 may be located in diverse geographical locations. Base station 105 may have an antenna array having several rows and columns of antenna ports that base station 105 can use to support beamforming for communication with UE 115. Similarly, UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations.

[0066] In some cases, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communication at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. The Radio Link Control (RLC) layer may perform packet segmentation and reassembly for communication over logical channels. The Media Access Control (MAC) layer may perform priority processing and multiplexing of logical channels to transport channels. The MAC layer may also use Hybrid Automatic Retransmission Requests (HARQ) to improve link efficiency by performing retransmissions at the MAC layer. In the control plane, the Radio Resource Control (RRC) protocol layer may establish, configure, and maintain RRC connections between the UE 115 and the base station 105 or core network 130, supporting radio bearers for user plane data. At the physical layer, transport channels may be mapped to physical channels.

[0067] The time interval in LTE or NR is, for example, T s= This can be expressed as a multiple of the basic time unit, which may refer to a sampling period of 1 / 30,720,000 seconds. The time interval of the communication resource may be organized according to radio frames, each having a duration of 10 milliseconds (ms), where the frame duration is T f =307,200T s It can be expressed as follows. A wireless frame can be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may contain 10 subframes numbered from 0 to 9, each subframe having a duration of 1 ms. A subframe may be further divided into two slots, each having a duration of 0.5 ms, and each slot may contain 6 or 7 modulated symbol periods (for example, depending on the length of the cyclic prefix prepared for each symbol period). Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communication system 100 and may be called a transmission time interval (TTI). In other cases, the smallest scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (for example, in a burst of shortened TTI (sTTI) or in a selected component carrier using sTTI).

[0068] In some wireless communication systems, a slot may be further divided into multiple minislots, each containing one or more symbols. In some cases, the symbols or minislots within a minislot may be the smallest unit of scheduling. Each symbol may have a varying duration, for example, depending on the subcarrier interval or the frequency band of operation. Furthermore, some wireless communication systems may implement slot aggregation, where multiple slots or minislots are aggregated together and used for communication between the UE 115 and the base station 105.

[0069] The term "carrier" refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communication over communication link 125. For example, the carrier of communication link 125 may include a portion of the radio frequency spectrum band operating according to a physical layer channel for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. The carrier may be associated with a predetermined frequency channel (e.g., an Advanced Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and may be arranged according to a channel raster for discovery by UE 115. The carrier may be downlink or uplink (e.g., in FDD mode), or may be configured to carry downlink and uplink communications (e.g., in TDD mode). In some examples, the signal waveform transmitted over the carrier may consist of multiple subcarriers (e.g., using multicarrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM).

[0070] The organizational structure of a carrier may differ for various radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR). For example, communications over a carrier may be organized according to TTI or slots, each of which may include user data, as well as control information or control signaling to support the decoding of user data. A carrier may also include dedicated capture signaling (e.g., synchronization signals or system information) and control signaling to coordinate operations with respect to the carrier. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have capture signaling or control signaling to coordinate operations with respect to other carriers.

[0071] In some cases, base station 105 may be a source base station 105, and one or more UEs 115 may be configured using one or more CHO configurations for one or more target base stations 105. For each target base station 105, one or more relevant conditions may be provided that can trigger the UE 115 to initiate a handover to a specific target base station 105 (for example, based on measurement thresholds for one or more target base station 105 measurements, one or more source base station 105 measurements, or a combination thereof). In some cases, the CHO configuration may include fault handling information, deconfiguration criteria, or a combination thereof.

[0072] Figure 2 shows an example of a wireless communication system 200 having a source base station and a target base station that supports CHO deconfiguration and fault handling in wireless communication according to aspects of the present disclosure. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. The wireless communication system 200 may include a source base station 105-a, a first target base station 105-b, and a second target base station 105-c, which may be an example of the base station 105 described with reference to Figure 1, and a UE 115-a, which may be an example of the UE 115 described with reference to Figure 1. The wireless communication system 200 shows an example of a conditional handover procedure in which the communication connection between the UE 115-a and a source cell served by the source base station 105-a (e.g., the first base station) is handed over to one of the first target base station 105-b or the second target base station 105-c.

[0073] Initially, UE115-a and source base station 105-a may be connected and exchanging information via a first communication connection 205. In some cases, UE115-a may transmit one or more measurement reports, which may provide one or more measurements to several neighboring base stations, including source base station 105-a and first target base station 105-b and second target base station 105-c. Based on the measurements in the measurement reports, source base station 105-a may identify one or more neighboring base stations 105 that are good candidates for handover for UE115-a (for example, based on signal strength measurements exceeding a threshold). In this example, source base station 105-a may identify first target base station 105-b and second target base station 105-c as handover candidates and may communicate a handover request to each identified candidate (for example, via backhaul link 134). In this example, the first target base station 105-b may perform authorization control based on the received handover request, reserve some resources for UE 115-a (e.g., a conflict-free random access preamble, random access resources, etc.), and provide information for random access to the source base station 105-a, which may be used to configure the first CHO configuration 215-a. Similarly, the second target base station 105-c may perform authorization control based on the received handover request, reserve some resources for UE 115-a, and provide information for random access to the source base station 105-a, which may be used to configure the second CHO configuration 215-b.

[0074] Source base station 105-a may provide a CHO configuration to UE 115-a, which may be used by UE 115-a to autonomously initiate a handover to a second communication connection 210. In some cases, the CHO configuration may be provided in RRC signaling transmitted to UE 115-a (for example, in an RRC reconfiguration message). The CHO configuration may provide, for example, the cell ID of the associated target base station 105, information for random access to the target base station 105 (e.g., a non-conflict random access resource, a random access preamble, a cell-specific radio network temporary identifier (C-RNTI), etc.), and one or more measurement thresholds that will be used to trigger a handover to the associated target base station 105 (e.g., an RRM threshold, a channel quality metric threshold, a signal strength metric threshold, etc.). According to the various techniques provided herein, the CHO configuration provided to UE 115-a may also include one or more deconfiguration parameters, one or more fault handling parameters, or any combination thereof.

[0075] In some cases, the deconfiguration parameters in the CHO configuration may provide event-based deconfiguration and may include one or more timers and one or more deconfiguration thresholds for each CHO target base station 105-b and 105-c or any combination thereof. Optionally, in some cases, one or more timers may include a validity timer that starts when a handover request is acknowledged and responded to by the source base station 105-a. In some cases, the validity timer (e.g., valTimer_TgNB) may be maintained by the source base station 105-a and target base stations 105-b and 105-c, and each target base station 105-b and 105-c may reserve resources for UE 115-a during the duration of the validity timer. In other cases, UE 115-a may also receive validity timer instructions associated with each target base station 105-b and 105-c having a CHO configuration and may deconfigure the associated CHO configuration upon expiration of the associated validity timer. In other cases, source base station 105-a may transmit an explicit release of the CHO configuration to target base station 105-b or 105-c whose validity timer has expired, in which case UE 115-a does not need to maintain the validity timer, or multiple validity timers for each target base station 105-b and 105-c. In some cases, source base station 105-a may determine the duration of the validity timer based on an estimate of UE 115-a movement, the target signal strength measured at UE 115-a, changes in the measured values ​​at UE 115-a over time, an estimate of the traffic load of source base station 105-a or target base station 105-b or 105-c (for example, as tracked by each base station 105), or any combination thereof.

[0076] In some cases, the CHO configuration may include one or more deconfiguration thresholds that provide criteria for deconfiguring the CHO. In such cases, if the UE115-a measurement meets the threshold-based criteria for deconfiguration for the CHO target base station 105-b or 105-c, the UE115-a may release the CHO configuration without waiting for explicit instructions from the source base station 105-a. Releasing the CHO configuration may include releasing the RRC configuration of the target base station 105-b or 105-c, as well as the associated measurement reporting configurations corresponding to the handover trigger and the CHO deconfiguration trigger. In some cases, the UE115-a may send a measurement report to the source base station 105-a so that the deconfiguration is notified to the network and the target base station 105-b or 105-c can release the resources reserved for the UE115-a. In some cases, a measurement report (e.g., an RRC measurement report message) may include a deconfiguration instruction (e.g., the cell ID of the target base station 105-b or 105-c being deconfigured). When the CHO configuration for target base station 105-b or 105-c is deconfigured, UE 115-a may cease performing and evaluating measurements to determine whether target base station 105-b or 105-c satisfies the handover criteria or the CHO deconfiguration criteria. In some cases, one or more measurement events may be specified for CHO deconfiguration. In some examples, such measurement events may include event 1, where adjacent cell measurements (e.g., signal strength, channel quality metric, etc.) fall below a threshold; event 2, where measurements at source base station 105-a (e.g., source primary cell (SpCell)) are better than a first threshold and measurements at target base station 105-b or 105-c are worse than a second threshold; event 3, where the measurement offset between the measurements at target base station 105-b or 105-c and source base station 105-a exceeds an offset threshold; or any combination thereof. Upon detection of one or more of these measurement events, UE 115-a may release the associated CHO configuration and provide a measurement report to source base station 105-a (e.g., including an instruction to deconfigure).In some cases, the measurement thresholds configured within each CHO may differ for each target base station 105-b and 105-c.

[0077] In some cases, the CHO configuration may include, as an addition or alternative, one or more timers for use in detecting handover failures. In some cases, one or more timers may include a conditional handover timer (e.g., CHO_timer_TgNB) that is invoked by UE115-a when a random access request for the handover procedure is sent. In such a case, UE115-a may, for example, determine that the CHO criteria for a handover from source base station 105-a to a first target base station 105-b are met, and may send a random access request to the first target base station 105-a and invoke the conditional handover timer. If the conditional handover timer expires before UE115-a establishes a connection with the first target base station 105-b, UE115-a may assume that the random access procedure has failed and invoke failure handling. If UE115-a maintains an effectiveness timer for the first target base station 105-b, UE115-a may stop the effectiveness timer when it sends a random access request. In some cases, fault handling may include selecting a second target base station 105-c (for example, another base station having a CHO configuration that satisfies UE115-a's CHO criteria for initiating a handover) and sending a random access request to the second target base station 105-c. UE115-c may activate a second conditional access timer associated with the second target base station 105-c, and this process may continue until the execution of the random access procedure is successful or until UE115-a runs out of CHO targets that satisfy the CHO criteria, at which point base station 105-b may declare a radio link failure and activate the RRC re-establishment procedure. In some cases, the conditional handover timer may be different for each of the different target base stations. Table 1 below includes examples of conditional handover timer start criteria, stop criteria, and fault actions to be taken when the conditional handover timer expires.

[0078] [Table 1]

[0079] Figure 3 shows an example of a general process flow 300 for a CHO that supports CHO deconfiguration and fault handling in wireless communications according to aspects of the present disclosure. In some examples, the process flow 300 may implement aspects of wireless communications systems 100 or 200. The process flow in this example includes UE 115-b, which may be an example of a UE described with reference to Figures 1 and 2, a source base station 105-d, a first target base station 105-e, and a second target base station 105-f, which may be examples of base stations described with reference to Figures 1 and 2. The process flow 300 includes functions and communications performed by UE 115-b and base stations 105-d, 105-e, and 105-f in the context of a conditional handover procedure.

[0080] In the following description of process flow 300, the operations between UE115-b and base stations 105-d, 105-e, and 105-f may be transmitted in an order different from that shown, or the operations may be performed in a different order or at different times. Some operations may also be omitted from process flow 300, or other operations may be added to process flow 300. While base stations 105 and UE115-b are shown as performing some of the operations in process flow 300, it should be understood that any wireless device may perform the operations shown.

[0081] In 305, UE115-b may transmit a measurement report to source base station 105-d. The measurement report may include one or more channel measurements for source base station 105-d, as well as measurements for a number of neighboring base stations, which may include a first target base station 105-e and a second target base station 105-f. The measurement report may be a “low” threshold measurement report, which may indicate that the channel measurements related to source base station 105-d are below a threshold used to indicate that source base station 105-d should constitute a CHO with respect to UE115-b.

[0082] In 310, the source base station 105-d may send a handover request to the first target base station 105-e. Furthermore, in 315, the source base station 105-d may send a handover request to the second target base station 105-f. In some cases, the source base station 105-d may select the first target base station 105-e and the second target base station 105-f for the handover request based on relevant measurements from the measurement report of the UE 115-b (for example, based on neighboring base station measurements that are above a threshold or better than other neighboring base station measurements). This example shows two target base stations 105, but more or fewer target base stations 105 may be identified for the CHO configuration. In some cases, the handover request may include handover information related to the UE 115-b, and similarly may include a duration for the effectiveness timer as described herein.

[0083] In 320, the first target base station 105-e may perform authorization control in response to receiving a handover request. Similarly, in 325, the second target base station 105-f may perform authorization control in response to receiving a handover request. The authorization control may determine that resources (e.g., C-RNTI, non-conflicting random access resources, random access preamble, etc.) may be reserved for UE 115-c.

[0084] In 330, the first target base station 105-e may send a handover request recognition response to the source base station 105-d. Furthermore, in this example, in 335, the second target base station 105-f may send a handover request recognition response to the source base station 105-d. The handover request recognition response may include information for use by the UE 115-b to establish a connection (e.g., a random access preamble, C-RNTI, etc.). The source base station 105-d may receive the handover request recognition response and determine a CHO criterion for each target cell for use by the UE 115-b to trigger a CHO. The CHO criterion may include, for example, one or more measurement thresholds for the relevant target base station 105, the source base station 105-d, or any combination thereof.

[0085] In 340, source base station 105-d may transmit CHO configuration information to UE 115-b in the RRC reconfiguration message. In some cases, the RRC reconfiguration message may indicate that a first target base station 105-e and a second target base station 105-f are configured for the CHO, may provide information for accessing the relevant base stations 105 (e.g., random access information, C-RNTI, etc.), and may provide handover thresholds associated with each target base station 105.

[0086] In step 345, UE115-b may determine that the conditions for handover to the first target base station 105-d are satisfied. Such a determination may be made, for example, based on one or more channel quality measurements of UE115-b compared with the CHO configuration provided by source base station 105-d. In step 350, UE115-b may initiate a Random Access Channel (RACH) procedure with the first target base station 105-e and execute the handover procedure.

[0087] Figure 4 shows an example of a process flow 400 for configuring and then releasing a CHO configuration in a wireless communication according to an aspect of the present disclosure. In some examples, the process flow 400 may implement an aspect of the wireless communication system 100 or 200. The process flow in this example includes a UE 115-c, which may be an example of a UE described with reference to Figures 1 and 2, a source base station 105-g, which may be an example of a base station described with reference to Figures 1 and 2, and a target base station 105-h. The process flow 400 includes functions and communications performed by UE 115-c and base stations 105-g and 105-h in the context of a conditional handover procedure.

[0088] In the following description of process flow 400, the operations between UE115-c and base stations 105-g and 105-h may be transmitted in an order different from that shown, or the operations may be performed in a different order or at different times. Some operations may also be omitted from process flow 400, or other operations may be added to process flow 400. While base stations 105 and UE115-c are shown as performing some of the operations in process flow 400, it should be understood that any wireless device may perform the operations shown.

[0089] In 405, UE115-c may transmit a measurement report to source base station 105-g. The measurement report may include one or more channel measurements for source base station 105-g, as well as measurements for a number of neighboring base stations, which may include target base station 105-h. The measurement report may be a “low” threshold measurement report, which may indicate that the channel measurements related to source base station 105-g are below a threshold used to indicate that source base station 105-g should constitute a CHO with respect to UE115-c.

[0090] In 410, the source base station 105-g may send a handover request to the target base station 105-h. The example in Figure 4 shows a single target base station 105-h, but in other cases, multiple different target base stations may be configured for the CHO, and the operation in Figure 4 may be used for any number of target base stations. In some cases, the source base station 105-g may select the target base station 105-h for the handover request based on relevant measurements from the measurement report of the UE 115-c (for example, based on an adjacent base station measurement that is above a threshold or better than other adjacent base station measurements). In some cases, the handover request may include handover information related to the UE 115-c, and may also include a duration for an effectiveness timer as described herein.

[0091] In step 415, the target base station 105-h may perform authorization control in response to receiving a handover request. The authorization control may determine that resources (e.g., C-RNTI, non-conflicting random access resources, random access preamble, etc.) can be reserved for UE 115-c.

[0092] In 420, the target base station 105-h may send a handover request recognition response to the source base station 105-g. The handover request recognition response may include information (e.g., a random access preamble, C-RNTI, etc.) for use by the UE 115-c to establish a connection with the target base station 105-h. The source base station 105-g may receive the handover request recognition response and determine a CHO criterion for the target cell for use by the UE 115-c to trigger a CHO. The CHO criterion may include one or more measurement thresholds (e.g., measThreshHO_TgNB) for, for example, the target base station 105-h (and for any other configured target base stations), the source base station 105-g, or any combination thereof.

[0093] In 425, source base station 105-g may transmit CHO configuration information to UE115-c in the RRC reconfiguration message. In some cases, the RRC reconfiguration message may indicate that target base station 105-h is configured for CHO, may provide information for accessing the associated base station 105 (e.g., random access information, C-RNTI, etc.), and may provide handover thresholds associated with each target base station 105-h.

[0094] In 430, the source base station may determine that UE115-c is moving away from the target base station 105-h. In some cases, such a determination may be made based on one or more measurement reports provided by UE115-c, such as signal strength measurements of UE115-c, positioning information of UE115-c, etc.

[0095] At 435, source base station 105-g may send another RRC reconfiguration to UE115-c to release the CHO configuration to target base station 105-h. At 440, source base station 105-g may send a handover cancellation to target base station 105-h to cancel the CHO configuration. UE115-c and target base station 105-h may remove the CHO configuration based on the signaling from source base station 105-g.

[0096] Figure 5 shows an example of a process flow 500 supporting CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. In some examples, the process flow 500 may implement an aspect of wireless communications system 100 or 200. The process flow in this example includes UE 115-d, which may be an example of a UE described with reference to Figures 1 and 2, a source base station 105-i, which may be an example of a base station described with reference to Figures 1 and 2, and a target base station 105-j. The process flow 500 includes functions and communications performed by UE 115-d and base stations 105-i and 105-j in the context of a conditional handover procedure.

[0097] In the following description of process flow 500, the operations between UE115-d and base stations 105-i and 105-j may be transmitted in an order different from that shown, or the operations may be performed in a different order or at different times. Some operations may also be omitted from process flow 500, or other operations may be added to process flow 500. While base stations 105 and UE115-d are shown as performing some of the operations in process flow 500, it should be understood that any wireless device may perform the operations shown.

[0098] In 505, UE115-d may transmit a measurement report to source base station 105-i. The measurement report may include one or more channel measurements for source base station 105-i, as well as measurements for several neighboring base stations, which may include target base station 105-j. The measurement report may be a “low” threshold measurement report, which may indicate that the channel measurements related to source base station 105-i are below a threshold used to indicate that source base station 105-i should constitute a CHO to UE115-d.

[0099] In 510, the source base station 105-i may send a handover request to the target base station 105-j. The example in Figure 5 shows a single target base station 105-j, but in other cases, multiple different target base stations may be configured for the CHO, and the operation in Figure 5 may be used for any number of target base stations. In some cases, the source base station 105-i may select the target base station 105-j for the handover request based on relevant measurements from the measurement report of the UE 115-d (for example, based on an adjacent base station measurement that is above a threshold or better than other adjacent base station measurements). In some cases, the handover request may include handover information related to the UE 115-d, and may also optionally include a duration for the validity timer 540. If multiple CHO configurations are configured for multiple target base stations, there may be multiple different validity timers for different target base stations.

[0100] In step 515, the target base station 105-j may perform authorization control in response to receiving a handover request. The authorization control may determine that resources (e.g., C-RNTI, non-conflicting random access resources, random access preamble, etc.) may be reserved for UE 115-d.

[0101] In 520, the target base station 105-j may send a handover request recognition response to the source base station 105-i. The handover request recognition response may include information (e.g., a random access preamble, C-RNTI, etc.) for use by the UE 115-d to establish a connection with the target base station 105-j. The source base station 105-i may receive the handover request recognition response and determine a CHO criterion for the target cell for use by the UE 115-d to trigger the CHO. The CHO criterion may include, for example, one or more measurement thresholds (e.g., measThreshHO_TgNB) for the target base station 105-j (and for any other configured target base stations), the source base station 105-i, or any combination thereof. In this example, the CHO criterion may also include an effective duration (e.g., calTimer_TgNB) for the target base station 105-j.

[0102] In step 525, the source base station 105-i may transmit CHO configuration information to the UE 115-d in an RRC reconfiguration message. In some cases, the RRC reconfiguration message may indicate that the target base station 105-j is configured for the CHO, may provide information for accessing the associated base station 105 (e.g., random access information, C-RNTI, etc.), and may provide handover thresholds associated with each target base station 105-j. If the CHO configuration provided to the UE 115-d includes an effectiveness timer, the UE 115-d may start the effectiveness timer 540 associated with the target base station 105-j. In some cases, the source base station 105-i and the target base station 105-j may hold the effectiveness timer, and the UE 115-d may not hold the effectiveness timer 540, which may simplify the implementation in the UE 115-d. In such cases, when the effectiveness timer expires, the source base station 105-i may explicitly release the CHO through another RRC reconfiguration message. If UE115-d holds the validity timer 540, UE115-d may autonomously release the CHO configuration when the validity timer 540 expires, and base station 105 may also release the CHO configuration based on the validity timer held in base station 105.

[0103] In 530, UE115-d may determine that the conditions for a handover are satisfied while the validity timer is active. Such a determination may be made, for example, based on one or more channel quality measurements of UE115-d compared with the CHO configuration provided by source base station 105-i. In 535, UE115-d may initiate a RACH procedure with the first target base station 105-j and execute a handover procedure with the target base station 105-j.

[0104] Figure 6 shows an example of a process flow 600 supporting CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. In some examples, the process flow 600 may implement an aspect of wireless communications system 100 or 200. The process flow in this example includes UE115-e, which may be an example of a UE described with reference to Figures 1 and 2, a source base station 105-k, a first target base station 105-l, and a second target base station 105-m, which may be examples of base stations described with reference to Figures 1 and 2. The process flow 600 includes functions and communications performed by UE115-e and base stations 105-k, 105-l, and 105-m in the context of a conditional handover procedure.

[0105] In the following description of process flow 600, the operations between UE115-e and base stations 105-k, 105-l, and 105-m may be transmitted in an order different from that shown, or the operations may be performed in a different order or at different times. Some operations may also be omitted from process flow 600, or other operations may be added to process flow 600. While base stations 105 and UE115-e are shown as performing some of the operations in process flow 600, it should be understood that any wireless device may perform the operations shown.

[0106] In 605, UE115-e may transmit a measurement report to source base station 105-k. The measurement report may include one or more channel measurements for source base station 105-k, as well as measurements for a number of neighboring base stations, which may include a first target base station 105-l and a second target base station 105-m. The measurement report may be a “low” threshold measurement report, which may indicate that the channel measurements related to source base station 105-k are below a threshold used to indicate that source base station 105-k should constitute a CHO with respect to UE115-e.

[0107] In 610, the source base station 105-k, the first target base station 105-l, and the second target base station 105-m may perform target handover preparation (for example, based on a handover request, acknowledgment control, and handover request recognition response). Handover preparation may include determining information (e.g., random access preamble, C-RNTI, etc.) for use by the UE 115-e to establish a connection. The source base station 105-k may determine CHO criteria for each target cell for use by the UE 115-e to trigger a CHO. The CHO criteria may include, for example, one or more measurement thresholds for the relevant target base station 105, source base station 105-k, or any combination thereof. In this example, the CHO configuration may also include a CHO timer for each target base station 105-l and 105-m. In some cases, base station 105 may hold an effectiveness timer 620 and release the CHO configuration for the target cell when the relevant effectiveness timer expires.

[0108] In 615, source base station 105-k may transmit CHO configuration information to UE115-e in the RRC reconfiguration message. In some cases, the RRC reconfiguration message may indicate that a first target base station 105-l and a second target base station 105-m are configured for the CHO, may provide information for accessing the relevant base stations 105 (e.g., random access information, C-RNTI, etc.), and may provide handover thresholds associated with each target base station 105.

[0109] In 625, UE115-e may determine that the conditions for handover to the first target base station 105-l are satisfied. Such a determination may be based, for example, on one or more channel quality measurements of UE115-e compared with the CHO configuration provided by the source base station 105-k. In 630, UE115-e may initiate a Random Access Channel (RACH) procedure with the first target base station 105-l and start the CHO timer 635 associated with the first target base station 105-l when sending the initial random access request message. In this example, in 640, UE115-e may determine a CHO failure based on the expiration of the CHO timer 635 before completing the random access procedure with the first target base station 105-l. For example, UE115-e may not receive a random access response after one or more retransmissions of the random access request while the CHO timer 635 is active.

[0110] In 645, UE115-e may determine that the conditions for handover to the second target base station 105-m are satisfied. Such a determination may be made, for example, based on one or more channel quality measurements of UE115-e, which are compared with the CHO configuration provided by source base station 105-k while the CHO configuration of the second target base station 105-m is active. In 655, UE115-e may initiate a Random Access Channel (RACH) procedure with the first target base station 105-k and start the CHO timer 650 associated with the second target base station 105-m when sending the initial random access request message. In this example, the random access procedure with the second target base station 105-m may be successful, and UE115-e may complete the handover. If the CHO timer 650 expires before the random access procedure with the second target base station 105-m is completed, the UE 115-e may repeat the process to any other target base station that has an active CHO configuration. If multiple target base stations have CHO configurations and satisfy the conditions for handover, the UE 115-e may select one based on one or more predetermined criteria (e.g., the target base station with the best channel quality, the target base station with the shortest remaining time in the effectiveness timer, the CHO configured earliest, etc.). If there is a CHO failure and no other target base station is configured for a CHO, the UE 115-e may declare a radio link failure and initiate the RRC connection re-establishment procedure.

[0111] Figure 7 shows an example of a process flow 700 supporting CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. In some examples, the process flow 700 may implement an aspect of wireless communications system 100 or 200. The process flow in this example includes UE115-f, which may be an example of a UE described with reference to Figures 1 and 2; a source base station 105-n, which may be an example of a base station described with reference to Figures 1 and 2; and a target base station 105-o. The process flow 700 includes functions and communications performed by UE115-f and base stations 105-n and 105-o in the context of a conditional handover procedure.

[0112] In the following description of process flow 700, the operations between UE115-f and base stations 105-n and 105-o may be transmitted in an order different from that shown, or the operations may be performed in a different order or at different times. Some operations may also be omitted from process flow 700, or other operations may be added to process flow 700. While base stations 105 and UE115-f are shown as performing some of the operations in process flow 700, it should be understood that any wireless device may perform the operations shown.

[0113] In 705, UE115-f may transmit a measurement report to source base station 105-n. The measurement report may include one or more channel measurements for source base station 105-n, as well as measurements for a number of neighboring base stations, which may include target base station 105-o. The measurement report may be a “low” threshold measurement report, which may indicate that the channel measurements related to source base station 105-n are below a threshold used to indicate that source base station 105-n should constitute a CHO with respect to UE115-f.

[0114] In 710, the source base station 105-n may send a handover request to the target base station 105-o. The example in Figure 7 shows a single target base station 105-o, but in other cases, multiple different target base stations may be configured for the CHO, and the operation in Figure 7 may be used for any number of target base stations. In some cases, the source base station 105-n may select the target base station 105-o for the handover request based on relevant measurements from the measurement report of the UE115-f (for example, based on neighboring base station measurements that are above a threshold or better than other neighboring base station measurements). In some cases, the handover request may include handover information related to the UE115-f.

[0115] In step 715, the target base station 105-o may perform authorization control in response to receiving a handover request. The authorization control may determine that resources (e.g., C-RNTI, non-conflicting random access resources, random access preamble, etc.) can be reserved for UE 115-f.

[0116] In 720, the target base station 105-o may send a handover request recognition response to the source base station 105-n. The handover request recognition response may include information (e.g., a random access preamble, C-RNTI, etc.) for use by the UE 115-f to establish a connection with the target base station 105-o. The source base station 105-n may receive the handover request recognition response and determine a CHO criterion for the target cell for use by the UE 115-f to trigger the CHO. The CHO criterion may include, for example, one or more measurement thresholds (e.g., measThreshHO_TgNB) for the target base station 105-o (and for any other configured target base stations), the source base station 105-n, or any combination thereof. In this example, the CHO criterion may also include one or more deconfiguration criteria (e.g., measThreshDeconfig_TgNB) that, if satisfied, trigger the deconfiguration of the CHO. In some cases, the CHO criterion may also include a duration for one or more timers (e.g., an effectiveness timer, a CHO timer, or both).

[0117] In 725, the source base station 105-n may transmit CHO configuration information to UE115-f in the RRC reconfiguration message. In some cases, the RRC reconfiguration message may indicate that the target base station 105-o is configured for the CHO, may provide information for accessing the associated base station 105 (e.g., random access information, C-RNTI, etc.), and may provide handover thresholds and deconfiguration thresholds associated with each target base station 105-o.

[0118] In 730, UE115-f may determine that the conditions for deconfiguring target base station 105-o are satisfied. Such a determination may be based, for example, on one or more channel quality measurements of UE115-f compared to the CHO configuration provided by source base station 105-n. In 735, UE115-f may send a measurement report to source base station 105-n. In some cases, the measurement report may indicate that the CHO configuration for target base station 105-o is being deconfigured. CHO deconfiguration may include releasing the RRC configuration of target base station 105-o, and UE115-f may cease performing and evaluating measurements against whether target base station 105-o satisfies the handover criteria or the CHO deconfiguration criteria. In some cases, the measurement report (e.g., an RRC measurement report message) may include a deconfiguration instruction.

[0119] At 740, source base station 105-n may send a handover cancellation instruction to target base station 105-o. At 745, target base station 105-o may release the reserved resources for UE115-f in response to the handover cancellation instruction.

[0120] Figure 8 shows a block diagram 800 of a device 805 that supports CHO deconfiguration and fault handling in wireless communication according to an aspect of this disclosure. Device 805 may be an example of an aspect of UE 115 as described herein. Device 805 may include a receiver 810, a communications manager 815, and a transmitter 820. Device 805 may also include a processor. Each of these components may communicate with one another (for example, via one or more buses).

[0121] Receiver 810 may receive information such as packets, user data, or control information related to various information channels (e.g., control channels, data channels, and information related to CHO deconfiguration and fault handling in wireless communications). The information may be transmitted to other components of device 805. Receiver 810 may be an example of an embodiment of transceiver 1120, as described with reference to Figure 11. Receiver 810 may utilize a single antenna or a set of antennas.

[0122] The communication manager 815 may receive a conditional handover configuration from the source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from the source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; may determine a first conditional handover failure in response to the expiration of a first conditional handover timer before the completion of a first random access procedure; may determine, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met; may send a first random access request to the first target base station based on the conditional handover configuration in order to initiate a first random access procedure for the handover to the first target base station; and may start a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request.

[0123] The communication manager 815 may also receive conditional handover configurations from a source base station that indicate one or more conditional handover configurations relating to one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station, and may release a first conditional handover configuration of a first target base station and determine on the conditional handover configuration that a first deconfiguration measurement threshold for deconfiguring the first conditional handover configuration of the first target base station is met. The communication manager 815 may be an example of an embodiment of the communication manager 1110 described herein.

[0124] The communications manager 815 or its subordinate components may be implemented in hardware, in code executed by a processor (e.g., software or firmware), or in any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 815 or its subordinate components may be performed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC), an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

[0125] The communications manager 815 or its subordinate components may be physically located in various locations, including the distribution of functional parts so that they are implemented in different physical locations by one or more physical components. In some examples, the communications manager 815 or its subordinate components may be separate and different components according to various aspects of this disclosure. In some examples, the communications manager 815 or its subordinate components may be combined with one or more other hardware components, including, but not limited to, input / output (I / O) components, transceivers, network servers, other computing devices, one or more other components described in this disclosure, or combinations thereof according to various aspects of this disclosure.

[0126] Transmitter 820 may transmit signals generated by other components of device 805. In some examples, transmitter 820 may be located together with receiver 810 in a transceiver module. For example, transmitter 820 may be an example of an embodiment of transceiver 1120, which is described with reference to Figure 11. Transmitter 820 may utilize a single antenna or a set of antennas.

[0127] Figure 9 shows a block diagram 900 of a device 905 that supports CHO deconfiguration and fault handling in wireless communication according to an aspect of this disclosure. Device 905 may be device 805, or an example of an aspect of UE 115 as described herein. Device 905 may include a receiver 910, a communications manager 915, and a transmitter 940. Device 905 may also include a processor. Each of these components may communicate with one another (for example, via one or more buses).

[0128] The receiver 910 may receive information such as packets, user data, or control information related to various information channels (e.g., control channels, data channels, and information related to CHO deconfiguration and fault handling in wireless communications). The information may be transmitted to other components of device 905. The receiver 910 may be an example of an embodiment of the transceiver 1120 described with reference to Figure 11. The receiver 910 may utilize a single antenna or a set of antennas.

[0129] The communication manager 915 may be an example of an embodiment of the communication manager 815 as described herein. The communication manager 915 may include a handover configuration manager 920, a measurement manager 925, a random access manager 930, and a conditional handover timer 935. The communication manager 915 may be an example of an embodiment of the communication manager 1110 as described herein.

[0130] The handover configuration manager 920 may receive a conditional handover configuration from the source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from the source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations, and may determine a first conditional handover failure in response to the expiration of a first conditional handover timer before the completion of a first random access procedure.

[0131] The measurement manager 925 may determine, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met.

[0132] The random access manager 930 may send a first random access request to the first target base station based on a conditional handover configuration in order to invoke a first random access procedure for handover to the first target base station.

[0133] The conditional handover timer 935 may, in response to the transmission of a first random access request, start a first conditional handover timer to complete a first random access procedure.

[0134] In some cases, the handover configuration manager 920 may receive conditional handover configurations from a source base station that indicate one or more conditional handover configurations relating to one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station, and may also release a first conditional handover configuration of a first target base station.

[0135] The measurement manager 925 may determine, based on the conditional handover configuration, that a first deconfiguration measurement threshold for deconfiguring the first conditional handover configuration of the first target base station is met.

[0136] The transmitter 940 may transmit signals generated by other components of device 905. In some examples, the transmitter 940 may be located together with the receiver 910 in a transceiver module. For example, the transmitter 940 may be an example of an embodiment of the transceiver 1120 described with reference to Figure 11. The transmitter 940 may utilize a single antenna or a set of antennas.

[0137] Figure 10 shows a block diagram 1000 of a communications manager 1005 that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of this disclosure. Communications manager 1005 may be an example of an aspect of communications manager 815, communications manager 915, or communications manager 1110 as described herein. Communications manager 1005 may include a handover configuration manager 1010, a measurement manager 1015, a random access manager 1020, a conditional handover timer 1025, an optional validity timer 1030, and an RRC connection establishment component 1035. Each of these modules may communicate with each other directly or indirectly (for example, via one or more buses).

[0138] The handover configuration manager 1010 may receive a conditional handover configuration from the source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from the source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations.

[0139] In some examples, the handover configuration manager 1010 may determine a first conditional handover failure in response to the expiration of a first conditional handover timer before the completion of a first random access procedure.

[0140] In some examples, the handover configuration manager 1010 may receive conditional handover configurations from a source base station that indicate one or more conditional handover configurations associated with one or more target base stations, where each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station. In some examples, the handover configuration manager 1010 may release a first conditional handover configuration of a first target base station.

[0141] In some examples, the handover configuration manager 1010 may repeatedly determine, transmit, and start timers to any other target base stations configured for conditional handover in the event of further conditional handover failures.

[0142] In some examples, the handover configuration manager 1010 may, in response to the expiration of the first conditional handover timer, select a second target base station from the set of available target base stations based on one or more of the channel quality measurements associated with each of the set of available target base stations, the amount of time remaining in the validity timer associated with each of the set of available target base stations, or any combination thereof.

[0143] In some examples, the handover configuration manager 1010 may remove one or more of the radio resource control configuration, the first measurement, and the reporting configurations for the conditional handover trigger and the conditional handover deconfiguration trigger, or one or more timers associated with the first target base station, which are provided in the first conditional handover configuration.

[0144] In some examples, the handover configuration manager 1010 may cease evaluating conditional handover measurements related to a first target base station and whether such measurements satisfy conditional handover criteria or conditional handover deconfiguration criteria. In some cases, one or more timers include at least a first conditional handover timer for completing a first random access procedure with the first target base station.

[0145] In some cases, the first deconfiguration metric threshold is a channel quality threshold associated with a first target base station, where the first conditional handover configuration is released in response to the channel quality measurement of the first target base station being less than the channel quality threshold. In some cases, the first deconfiguration metric threshold includes a first threshold associated with a source base station and a second threshold associated with a first target base station, where the first conditional handover configuration is released in response to the first channel quality measurement of the source base station exceeding the first threshold and the second channel quality measurement of the first target base station being less than the second threshold. In some cases, the first deconfiguration metric threshold is a differential threshold, where the first conditional handover configuration is released in response to the difference in channel quality measurements between the source base station and the first target base station exceeding the differential threshold.

[0146] The measurement manager 1015 may determine, based on a conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met.

[0147] In some examples, the measurement manager 1015 may determine, based on the conditional handover configuration, that a first deconfiguration measurement threshold is met for deconfiguring the first conditional handover configuration of the first target base station.

[0148] In some examples, the measurement manager 1015 may determine, in response to the expiration of a first conditional handover timer, that a second measurement threshold is met to initiate a handover to a second target base station.

[0149] In some examples, the measurement manager 1015 may determine, based on a conditional handover configuration, that a second trigger measurement threshold for initiating a handover to a second target base station is met.

[0150] In some examples, the measurement manager 1015 may send a measurement report to the source base station indicating that the first conditional handover configuration of the first target base station is released. In some cases, the measurement report may include a deconfiguration instruction for the first target base station.

[0151] The random access manager 1020 may send a first random access request to the first target base station based on a conditional handover configuration in order to invoke a first random access procedure for handover to the first target base station.

[0152] In some examples, the random access manager 1020 may send a second random access request to the second target base station based on a conditional handover configuration in order to invoke a second random access procedure for handover to the second target base station.

[0153] The conditional handover timer 1025 may start a first conditional handover timer to complete a first random access procedure in response to the transmission of a first random access request. In some examples, the conditional handover timer 1025 may start a second conditional handover timer to complete a second random access procedure. In some cases, the first duration of the first conditional handover timer is different from the second duration of the second conditional handover timer.

[0154] If present, the validity timer 1030 may activate a first validity timer and a second validity timer in response to the reception of a conditional handover configuration. In some examples, the validity timer 1030 may delete a second conditional handover configuration in response to the expiration of the second validity timer. In some examples, the validity timer 1030 may deactivate the first validity timer when a first random access request is sent to a first target base station.

[0155] The RRC connection establishment component 1035 may initiate a connection re-establishment procedure if it determines that no other target base station is configured for a conditional handover.

[0156] Figure 11 shows a diagram of a system 1100 including a device 1105 that supports CHO deconfiguration and fault handling in wireless communication according to an aspect of the present disclosure. Device 1105 may be an example of, or include, a component of, device 805, device 905, or UE 115 as described herein. Device 1105 may include components for bidirectional voice and data communication, including components for transmitting and receiving communications, including a communications manager 1110, an I / O controller 1115, a transceiver 1120, an antenna 1125, a memory 1130, and a processor 1140. These components may communicate electronically via one or more buses (e.g., bus 1145).

[0157] The communication manager 1110 may receive a conditional handover configuration from the source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from the source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; may determine a first conditional handover failure in response to the expiration of a first conditional handover timer before the completion of a first random access procedure; may determine, based on the conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met; may send a first random access request to the first target base station based on the conditional handover configuration in order to initiate a first random access procedure for the handover to the first target base station; and may start a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request.

[0158] The communication manager 1110 may also receive conditional handover configurations from a source base station that indicate one or more conditional handover configurations relating to one or more target base stations, wherein each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station, and may release a first conditional handover configuration of a first target base station and determine, based on the conditional handover configuration, that a first deconfiguration measurement threshold for deconfiguring the first conditional handover configuration of the first target base station is met.

[0159] The I / O controller 1115 may manage input and output signals for device 1105. The I / O controller 1115 may also manage peripherals not integrated into device 1105. In some cases, the I / O controller 1115 may represent a physical connection or port to an external peripheral. In some cases, the I / O controller 1115 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. In other cases, the I / O controller 1115 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 1115 may be implemented as part of a processor. In some cases, a user may interact with device 1105 via the I / O controller 1115 or via hardware components controlled by the I / O controller 1115.

[0160] As described above, the transceiver 1120 can communicate bidirectionally via one or more antennas, wired links, or wireless links. For example, the transceiver 1120 may represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 1120 may also include a modem for modulating packets for transmission and providing the modulated packets to the antenna, and for demodulating packets received from the antenna.

[0161] In some cases, the wireless device may include a single antenna 1125. However, in some cases, the device may have two or more antennas 1125 that may be capable of transmitting or receiving multiple wireless transmissions simultaneously.

[0162] Memory 1130 may include RAM and ROM. Memory 1130 may store computer-readable computer executable code 1135, which, when executed, includes instructions that cause the processor to perform various functions described herein. In some cases, memory 1130 may include a BIOS that can control basic hardware or software operations, in particular, interactions with peripheral components or peripheral devices.

[0163] The processor 1140 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 1140 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 1140. The processor 1140 may be configured to execute computer-readable instructions stored in memory (e.g., memory 1130) to cause device 1105 to perform various functions (e.g., functions or tasks supporting CHO deconfiguration and fault handling in wireless communications).

[0164] Code 1135 may include instructions for carrying out aspects of this disclosure, including instructions for supporting wireless communication. Code 1135 may be stored in a non-temporary computer-readable medium, such as system memory or other types of memory. In some cases, Code 1135 may not be directly executable by the processor 1140, but may cause the computer to perform the functions described herein (for example, when compiled and executed).

[0165] Figure 12 shows a block diagram 1200 of a device 1205 that supports CHO deconfiguration and fault handling in wireless communication according to an aspect of the present disclosure. Device 1205 may be an example of an aspect of a base station 105 as described herein. Device 1205 may include a receiver 1210, a communications manager 1215, and a transmitter 1220. Device 1205 may also include a processor. Each of these components may communicate with one another (for example, via one or more buses).

[0166] Receiver 1210 may receive information such as packets, user data, or control information related to various information channels (e.g., control channels, data channels, and information related to CHO deconfiguration and fault handling in wireless communications). The information may be transmitted to other components of device 1205. Receiver 1210 may be an example of an embodiment of transceiver 1520, which will be described with reference to Figure 15. Receiver 1210 may utilize a single antenna or a set of antennas.

[0167] The communication manager 1215 may transmit to the UE one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a conditional handover time period for completing a random access procedure when the conditional handover of the UE from the source base station to each target base station is initiated, and each of the conditional handover configurations indicates the associated target base station, one or more measurement thresholds for initiating the handover of the UE from the source base station to the associated target base station, and the associated target base station's conditional handover time period.

[0168] The communication manager 1215 may also establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and transmit one or more conditional handover configurations to the UE, each indicating the associated target base station, the trigger measurement threshold for initiating a conditional handover to the associated target base station, and the conditional handover timer value for completing the conditional handover of the UE to the associated target base station. The communication manager 1215 may be an example of an embodiment of the communication manager 1510 described herein.

[0169] The communication manager 1215 or its subordinate components may be implemented in hardware, in code executed by a processor (e.g., software or firmware), or in any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 1215 or its subordinate components may be performed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC), an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

[0170] The communication manager 1215 or its subordinate components may be physically located in various locations, including the distribution of functional parts so that they are implemented in different physical locations by one or more physical components. In some examples, the communication manager 1215 or its subordinate components may be separate and different components according to various aspects of this disclosure. In some examples, the communication manager 1215 or its subordinate components may be combined with one or more other hardware components, including, but not limited to, input / output (I / O) components, transceivers, network servers, other computing devices, one or more other components described in this disclosure, or combinations thereof according to various aspects of this disclosure.

[0171] The transmitter 1220 may transmit signals generated by other components of device 1205. In some examples, the transmitter 1220 may be located together with the receiver 1210 in a transceiver module. For example, the transmitter 1220 may be an example of an embodiment of the transceiver 1520, which is described with reference to Figure 15. The transmitter 1220 may utilize a single antenna or a set of antennas.

[0172] Figure 13 shows a block diagram 1300 of a device 1305 that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of this disclosure. Device 1305 may be device 1205, or an example of an aspect of a base station 105 as described herein. Device 1305 may include a receiver 1310, a communications manager 1315, and a transmitter 1330. Device 1305 may also include a processor. Each of these components may communicate with one another (for example, via one or more buses).

[0173] Receiver 1310 may receive information such as packets, user data, or control information related to various information channels (e.g., control channels, data channels, and information related to CHO deconfiguration and fault handling in wireless communications). The information may be transmitted to other components of device 1305. Receiver 1310 may be an example of an embodiment of transceiver 1520, as described with reference to Figure 15. Receiver 1310 may utilize a single antenna or a set of antennas.

[0174] The communication manager 1315 may be an example of an embodiment of the communication manager 1215 as described herein. The communication manager 1315 may include a handover configuration manager 1320 and a UE handover manager 1325. The communication manager 1315 may be an example of an embodiment of the communication manager 1510 as described herein.

[0175] The handover configuration manager 1320 may establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a conditional handover time period for completing a random access procedure when the conditional handover of the UE from the source base station to each target base station is initiated.

[0176] The UE handover manager 1325 may transmit to the UE one or more conditional handover configurations, each indicating the associated target base station, one or more measurement thresholds for initiating a UE handover from the source base station to the associated target base station, and the conditional handover time period of the associated target base station.

[0177] The handover configuration manager 1320 may establish one or more conditional handover configurations with each target base station for conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a trigger measurement threshold for initiating the conditional handover of the UE to the associated target base station and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station.

[0178] The UE handover manager 1325 may send one or more conditional handover configurations to the UE, each indicating an associated target base station, a trigger measurement threshold for initiating a conditional handover to the associated target base station, and a conditional handover timer value for completing the UE's conditional handover to the associated target base station.

[0179] Transmitter 1330 can transmit signals generated by other components of device 1305. In some examples, transmitter 1330 may be located together with receiver 1310 in a transceiver module. For example, transmitter 1330 may be an example of an embodiment of transceiver 1520, which is described with reference to Figure 15. Transmitter 1330 may utilize a single antenna or a set of antennas.

[0180] Figure 14 shows a block diagram 1400 of a communications manager 1405 that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of this disclosure. The communications manager 1405 may be an example of an aspect of the communications manager 1215, communications manager 1315, or communications manager 1510 described herein. The communications manager 1405 may include a handover configuration manager 1410, a UE handover manager 1415, a timer manager 1420, and a measurement manager 1425. Each of these modules may communicate with one another directly or indirectly (for example, via one or more buses).

[0181] The handover configuration manager 1410 may establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a conditional handover time period for completing a random access procedure when the conditional handover of the UE from the source base station to each target base station is initiated.

[0182] In some examples, the handover configuration manager 1410 may establish one or more conditional handover configurations with each target base station for conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a trigger metric threshold for initiating a conditional handover of the UE to the associated target base station and a deconfiguration metric threshold for deconfiguring the conditional handover configuration of the associated target base station.

[0183] In some examples, the handover configuration manager 1410 may release the first conditional handover configuration of the first target base station in response to a measurement report. In some examples, the handover configuration manager 1410 may remove one or more of the radio resource control configuration, the first deconfiguration measurement threshold, the first trigger measurement threshold, or one or more timers associated with the first target base station that are included in the first conditional handover configuration. In some examples, the handover configuration manager 1410 may provide the first target base station with an instruction that the first conditional handover configuration is being released.

[0184] In some cases, the deconfiguration measurement threshold is a channel quality threshold associated with each respective target base station, where the conditional handover configuration of the first target base station is released in response to the channel quality measurement of the first target base station being less than the channel quality threshold of the first target base station. In some cases, the deconfiguration measurement threshold includes a first threshold associated with the source base station and a second threshold for each respective target base station, where the conditional handover configuration of the first target base station is released in response to the first channel quality measurement of the source base station exceeding the first threshold and the second channel quality measurement of the first target base station being less than the second threshold of the first target base station. In some cases, the deconfiguration measurement threshold is a differential threshold, where the conditional handover configuration associated with the first target base station is released in response to the difference in channel quality measurements between the source base station and the first target base station exceeding the differential threshold.

[0185] The UE handover manager 1415 may transmit to the UE one or more conditional handover configurations, each indicating the associated target base station, one or more measurement thresholds for initiating a UE handover from the source base station to the associated target base station, and the conditional handover time period of the associated target base station.

[0186] In some examples, the UE handover manager 1415 may transmit one or more conditional handover configurations to the UE, each specifying an associated target base station, a trigger metric threshold for initiating a conditional handover to the associated target base station, and a deconfiguration metric threshold for deconfiguring the conditional handover configuration of the associated target base station. In some cases, the UE autonomously deconfigures the first conditional handover configuration of the first target base station based on the expiration of a first validity period.

[0187] The timer manager 1420 may manage one or more time periods related to the CHO. In some cases, the conditional handover time period is determined based on one or more of the following: an estimate of the movement of the UE to each target base station, the traffic load of the source base station or each target base station, channel quality measurements to each target base station provided by the UE, or any combination thereof.

[0188] The measurement manager 1425 may receive a measurement report from the UE indicating that a first deconfiguration measurement threshold is met for deconfiguring the first conditional handover configuration of the first target base station.

[0189] Figure 15 shows a diagram of a system 1500 including a device 1505 that supports CHO deconfiguration and fault handling in wireless communications according to an aspect of the present disclosure. Device 1505 may be, or include, an example of a component of device 1205, device 1305, or base station 105 as described herein. Device 1505 may include components for bidirectional voice and data communications, including components for transmitting and receiving communications, including a communications manager 1510, a network communications manager 1515, a transceiver 1520, an antenna 1525, a memory 1530, a processor 1540, and an inter-station communications manager 1545. These components may communicate electronically via one or more buses (e.g., bus 1550).

[0190] The communication manager 1510 may transmit to the UE one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a conditional handover time period for completing a random access procedure when the conditional handover of the UE from the source base station to each target base station is initiated, and each of the conditional handover configurations indicates the associated target base station, one or more measurement thresholds for initiating the handover of the UE from the source base station to the associated target base station, and the associated target base station's conditional handover time period.

[0191] The communication manager 1510 may also establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station, and transmit one or more conditional handover configurations to the UE, each indicating the associated target base station, the trigger measurement threshold for initiating a conditional handover to the associated target base station, and the conditional handover timer value for completing the conditional handover of the UE to the associated target base station.

[0192] The network communication manager 1515 may manage communication with the core network (for example, via one or more wired backhaul links). For example, the network communication manager 1515 may manage the transfer of data communications for one or more client devices such as UE115.

[0193] As described above, the transceiver 1520 can communicate bidirectionally via one or more antennas, wired links, or wireless links. For example, the transceiver 1520 may represent a wireless transceiver and communicate bidirectionally with another wireless transceiver. The transceiver 1520 may also include a modem for modulating packets for transmission and providing the modulated packets to the antenna, and for demodulating packets received from the antenna.

[0194] In some cases, the wireless device may include a single antenna 1525. However, in some cases, the device may have two or more antennas 1525 that may be capable of simultaneously transmitting or receiving multiple wireless transmissions.

[0195] Memory 1530 may include RAM, ROM, or a combination thereof. Memory 1530 may store computer-readable code 1535, which, when executed by a processor (e.g., processor 1540), includes instructions that cause the device to perform various functions described herein. In some cases, memory 1530 may include a BIOS that can control basic hardware or software operations, in particular, interactions with peripheral components or peripheral devices.

[0196] The processor 1540 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 1540 may be configured to operate a memory array using a memory controller. In some cases, the memory controller may be integrated into the processor 1540. The processor 1540 may be configured to execute computer-readable instructions stored in memory (e.g., memory 1530) to cause device 1505 to perform various functions (e.g., functions or tasks supporting CHO deconfiguration and fault handling in wireless communications).

[0197] The inter-station communication manager 1545 may manage communication with other base stations 105 and may include a controller or scheduler for coordinating with other base stations 105 to control communication with the UE 115. For example, the inter-station communication manager 1545 may coordinate scheduling for transmissions to the UE 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communication manager 1545 may provide an X2 interface within the LTE / LTE-A wireless communication network technology for communication between base stations 105.

[0198] Code 1535 may include instructions for carrying out aspects of this disclosure, including instructions for supporting wireless communication. Code 1535 may be stored in a non-temporary computer-readable medium, such as system memory or other types of memory. In some cases, Code 1535 may not be directly executable by processor 1540, but may cause the computer to perform the functions described herein (for example, when compiled and executed).

[0199] Figure 16 shows a flowchart illustrating method 1600 for supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 1600 may be performed by a UE 115 or its components as described herein. For example, the operation of method 1600 may be performed by a communications manager as described with reference to Figures 8 to 11. In some examples, the UE may execute a set of instructions for controlling functional elements of the UE in order to perform the functions described below. In addition or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0200] In 1605, the UE may receive a conditional handover configuration from the source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from the source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations. The operation of 1605 may be performed according to the methods described herein. In some examples, the operation of 1605 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0201] In 1610, the UE may determine, based on a conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met. The operation of 1610 may be performed according to the methods described herein. In some examples, the operation of 1610 may be performed by a measurement manager as described with reference to Figures 8 to 11.

[0202] In 1615, the UE may send a first random access request to the first target base station based on a conditional handover configuration in order to invoke a first random access procedure for handover to the first target base station. The operation of 1615 may be performed according to the methods described herein. In some examples, the operation of 1615 may be performed by a random access manager as described with reference to Figures 8 to 11.

[0203] In 1620, the UE may, in response to the transmission of a first random access request, initiate a first conditional handover timer to complete a first random access procedure. The operation of 1620 may be performed according to the methods described herein. In some examples, the operation of 1620 may be performed by a conditional handover timer as described with reference to Figures 8 to 11.

[0204] In 1625, the UE may determine a first conditional handover failure in response to the expiration of a first conditional handover timer before completing the first random access procedure. The operation of 1625 may be performed according to the methods described herein. In some examples, the operation of 1625 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0205] Figure 17 shows a flowchart illustrating method 1700 supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 1700 may be performed by a UE 115 or its components as described herein. For example, the operation of method 1700 may be performed by a communications manager as described with reference to Figures 8 to 11. In some examples, the UE may execute a set of instructions for controlling functional elements of the UE in order to perform the functions described below. In addition or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0206] In 1705, the UE may receive a conditional handover configuration from the source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from the source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations. The operation of 1705 may be performed according to the methods described herein. In some examples, the operation of 1705 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0207] In 1710, the UE may determine, based on a conditional handover configuration, that a first measurement threshold for initiating a handover to a first target base station is met. The operation of 1710 may be performed according to the methods described herein. In some examples, the operation of 1710 may be performed by a measurement manager as described with reference to Figures 8 to 11.

[0208] In 1715, the UE may send a first random access request to the first target base station based on a conditional handover configuration in order to invoke a first random access procedure for handover to the first target base station. The operation of 1715 may be performed according to the methods described herein. In some examples, the operation of 1715 may be performed by a random access manager as described with reference to Figures 8 to 11.

[0209] In 1720, the UE may, in response to the transmission of a first random access request, initiate a first conditional handover timer to complete a first random access procedure. The operation of 1720 may be performed according to the methods described herein. In some examples, the operation of 1720 may be performed by a conditional handover timer as described with reference to Figures 8 to 11.

[0210] In 1725, the UE may determine a first conditional handover failure in response to the expiration of a first conditional handover timer before completing the first random access procedure. The operation of 1725 may be performed according to the methods described herein. In some examples, the operation of 1725 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0211] In 1730, the UE may determine that a second measurement threshold for initiating a handover to a second target base station is met in response to the expiration of a first conditional handover timer. The operation of 1730 may be performed according to the methods described herein. In some examples, the operation of 1730 may be performed by a measurement manager as described with reference to Figures 8 to 11.

[0212] In 1735, the UE may send a second random access request to the second target base station based on a conditional handover configuration in order to invoke a second random access procedure for handover to the second target base station. The operation of 1735 may be performed according to the methods described herein. In some examples, the operation of 1735 may be performed by a random access manager as described with reference to Figures 8 to 11.

[0213] In 1740, the UE may initiate a second conditional handover timer to complete the second random access procedure. The operation of 1740 may be performed according to the methods described herein. In some examples, the operation of 1740 may be performed by a conditional handover timer as described with reference to Figures 8 to 11.

[0214] In 1745, the UE may, in the event of further conditional handover failures, repeatedly determine, transmit, and initiate to any other target base station configured for conditional handover. The operation of 1745 may be performed according to the methods described herein. In some examples, the operation of 1745 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0215] In 1750, if the UE determines that no other target base station is configured for the conditional handover, it may invoke the re-establishment procedure. The operation of 1750 may be performed according to the methods described herein. In some examples, the operation of 1750 may be performed by RRC connection establishment components as described with reference to Figures 8 to 11.

[0216] Figure 18 shows a flowchart illustrating method 1800 for supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 1800 may be performed by a UE 115 or its components as described herein. For example, the operation of method 1800 may be performed by a communications manager as described with reference to Figures 8 to 11. In some examples, the UE may execute a set of instructions for controlling functional elements of the UE in order to perform the functions described below. In addition or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0217] In 1805, the UE may receive from the source base station a conditional handover configuration indicating one or more conditional handover configurations relating to one or more target base stations, where each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station. The operation of 1805 may be performed according to the methods described herein. In some examples, the operation of 1805 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0218] In 1810, the UE may determine, based on the conditional handover configuration, that a first deconfiguration metric threshold for deconfiguring the first conditional handover configuration of the first target base station is met. The operation of 1810 may be performed according to the methods described herein. In some examples, the operation of 1810 may be performed by a metric manager as described with reference to Figures 8 to 11.

[0219] In 1815, the UE may release the first conditional handover configuration of the first target base station. The operation of 1815 may be performed according to the methods described herein. In some examples, the operation of 1815 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0220] Figure 19 shows a flowchart illustrating method 1900 supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 1900 may be performed by a UE 115 or its components as described herein. For example, the operation of method 1900 may be performed by a communications manager as described with reference to Figures 8 to 11. In some examples, the UE may execute a set of instructions for controlling functional elements of the UE in order to perform the functions described below. In addition or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0221] In 1905, the UE may receive from the source base station a conditional handover configuration indicating one or more conditional handover configurations relating to one or more target base stations, where each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station. The operation of 1905 may be performed according to the methods described herein. In some examples, the operation of 1905 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0222] In 1910, the UE may determine, based on the conditional handover configuration, that a first deconfiguration metric threshold for deconfiguring the first conditional handover configuration of the first target base station is met. The operation of 1910 may be performed according to the methods described herein. In some examples, the operation of 1910 may be performed by a metric manager as described with reference to Figures 8 to 11.

[0223] In 1915, the UE may release the first conditional handover configuration of the first target base station. The operation of 1915 may be performed according to the methods described herein. In some examples, the operation of 1915 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0224] In 1920, the UE may determine, based on a conditional handover configuration, that a second trigger measurement threshold for initiating a handover to a second target base station is met. The operation of 1920 may be performed according to the methods described herein. In some examples, the operation of 1920 may be performed by a measurement manager as described with reference to Figures 8 to 11.

[0225] In 1925, the UE may send a random access request to the second target base station based on the second conditional handover configuration of the second target base station in order to invoke a random access procedure for handover to the second target base station. The operation of 1925 may be performed according to the methods described herein. In some examples, the operation of 1925 may be performed by a random access manager as described with reference to Figures 8 to 11.

[0226] Figure 20 shows a flowchart illustrating method 2000 for supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 2000 may be performed by a UE 115 or its components as described herein. For example, the operation of method 2000 may be performed by a communications manager as described with reference to Figures 8 to 11. In some examples, the UE may execute a set of instructions for controlling functional elements of the UE in order to perform the functions described below. In addition or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0227] In 2005, the UE may receive from the source base station a conditional handover configuration indicating one or more conditional handover configurations associated with one or more target base stations, where each of the one or more conditional handover configurations includes a trigger measurement threshold for initiating a conditional handover to the associated target base station and a deconfiguration measurement threshold for deconfiguring the conditional handover configuration of the associated target base station. The operation of 2005 may be performed according to the methods described herein. In some examples, the operation of 2005 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0228] In 2010, the UE may determine, based on the conditional handover configuration, that a first deconfiguration metric threshold for deconfiguring the first conditional handover configuration of the first target base station is met. The operation of 2010 may be performed according to the methods described herein. In some examples, the operation of 2010 may be performed by a metric manager as described with reference to Figures 8 to 11.

[0229] In 2015, the UE may release the first conditional handover configuration of the first target base station. The operation of 2015 may be performed according to the methods described herein. In some examples, the operation of 2015 may be performed by a handover configuration manager as described with reference to Figures 8 to 11.

[0230] In 2020, the UE may send a measurement report to the source base station indicating that the first conditional handover configuration of the first target base station is released. The operation of 2020 may be performed according to the methods described herein. In some examples, the operation of 2020 may be performed by a measurement manager as described with reference to Figures 8 to 11.

[0231] In 2025, the measurement report includes a deconfiguration instruction for the first target base station. The operation of 2025 may be performed according to the methods described herein. In some examples, the operation of 2025 may be performed by a measurement manager as described with reference to Figures 8 to 11.

[0232] Figure 21 shows a flowchart illustrating method 2100 for supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 2100 may be performed by a base station 105 or its components as described herein. For example, the operation of method 2100 may be performed by a communications manager as described with reference to Figures 12-15. In some examples, the base station may execute a set of instructions for controlling the functional elements of the base station in order to perform the functions described below. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functions described below.

[0233] In 2105, the base station may establish one or more conditional handover configurations with each of the target base stations for a conditional handover of a UE from the source base station to one or more target base stations, where each conditional handover configuration includes a conditional handover time period for completing a random access procedure when the conditional handover of the UE from the source base station to each target base station is initiated. The operation of 2105 may be performed according to the methods described herein. In some examples, the operation of 2105 may be performed by a handover configuration manager as described with reference to Figures 12 to 15.

[0234] In 2110, the base station may transmit to the UE one or more conditional handover configurations, each indicating an associated target base station, one or more measurement thresholds for initiating a UE handover from the source base station to the associated target base station, and a conditional handover time period for the associated target base station. The operation of 2110 may be performed according to the methods described herein. In some examples, the operation of 2110 may be performed by a UE handover manager as described with reference to Figures 12 to 15.

[0235] Figure 22 shows a flowchart illustrating method 2200 for supporting CHO deconfiguration and fault handling in wireless communications according to aspects of this disclosure. The operation of method 2200 may be performed by a base station 105 or its components as described herein. For example, the operation of method 2200 may be performed by a communications manager as described with reference to Figures 12-15. In some examples, the base station may execute a set of instructions for controlling the functional elements of the base station in order to perform the functions described below. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functions described below.

[0236] In 2205, a base station may establish one or more conditional handover configurations with each target base station for a conditional handover of a UE from a source base station to one or more target base stations, where each conditional handover configuration includes a trigger measurement threshold for initiating the conditional handover of the UE to the associated target base station and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station. The operation of 2205 may be performed according to the methods described herein. In some examples, the modes of operation of 2205 may be performed by a handover configuration manager as described with reference to Figures 12 to 15.

[0237] In 2210, the base station may transmit one or more conditional handover configurations to the UE, each indicating an associated target base station, a trigger measurement threshold for initiating a conditional handover to the associated target base station, and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station. The operation of 2210 may be performed according to the methods described herein. In some examples, the operation of 2210 may be performed by a UE handover manager as described with reference to Figures 12 to 15.

[0238] It should be noted that the methods described herein describe possible implementations, that the operations and steps may be reconfigured or otherwise modified, and that other implementations are possible. Furthermore, two or more embodiments of the methods may be combined.

[0239] Embodiment 1: A method for wireless communication in a UE, comprising: receiving a conditional handover configuration from a source base station, which indicates one or more target base stations, one or more measurement thresholds for initiating a handover from a source base station to one or more target base stations, and one or more timers associated with the handover to one or more target base stations; determining, at least partially, that a first measurement threshold for initiating a handover to a first target base station is met; transmitting a first random access request to a first target base station, at least partially based on the conditional handover configuration, in order to initiate a first random access procedure for a handover to the first target base station; starting a first conditional handover timer for completing the first random access procedure in response to the transmission of the first random access request; and determining a first conditional handover failure in response to the expiration of the first conditional handover timer before the completion of the first random access procedure.

[0240] Embodiment 2: The method of Embodiment 1, wherein one or more timers include at least a first conditional handover timer for completing a first random access procedure with a first target base station.

[0241] Embodiment 3: The method of Embodiment 1 or 2, wherein the conditional handover configuration includes at least a first conditional handover configuration for a first target base station and a second conditional handover configuration for a second target base station.

[0242] Embodiment 4: Any method from Embodiments 1 to 3, further comprising activating a first validity timer and a second validity timer in response to the reception of a conditional handover configuration, and deactivating a second conditional handover configuration in response to the expiration of the second validity timer.

[0243] Embodiment 5: The method of Embodiment 4, further comprising stopping a first validity timer when a first random access request is transmitted to a first target base station.

[0244] Embodiment 6: Any method of Embodiments 1 to 5, further comprising: determining that a second measurement threshold for initiating a handover to a second target base station is met in response to the expiration of a first conditional handover timer; sending a second random access request to the second target base station based at least in part on a conditional handover configuration in order to initiate a second random access procedure for a handover to the second target base station; and starting a second conditional handover timer for completing the second random access procedure.

[0245] Embodiment 7: The method of Embodiment 6, further comprising initiating a connection re-establishment procedure when it is determined that no other target base station is configured for a conditional handover.

[0246] Embodiment 8: The method of Embodiment 6 or 7, wherein the first duration of the first conditional handover timer is different from the second duration of the second conditional handover timer.

[0247] Embodiment 9: Any method of Embodiments 6 to 8, further comprising selecting a second target base station from a plurality of available target base stations, at least in part, on channel quality measurements associated with each of the plurality of available target base stations, in response to the expiration of a first conditional handover timer.

[0248] Embodiment 10: Any method of Embodiments 6 to 9, wherein the second target base station is selected at least in part on the basis that the second target base station has a shorter remaining effective timer duration than the others of the multiple available target base stations.

[0249] Embodiment 11: Any method from Embodiments 1 to 10, further comprising receiving a deconfiguration message from a source base station that deconfigures one or more conditional handover configurations, and deconfiguring one or more conditional handover configurations based at least in part on the deconfiguration message.

[0250] Embodiment 12: The method of Embodiment 11, wherein the deconfiguration message is received from the source base station in radio resource control signaling.

[0251] Embodiment 13: The method of Embodiment 11 or 12, further comprising removing one or more of the wireless resource control configuration, or the first measurement, and reporting configurations for the conditional handover trigger, provided in the first conditional handover configuration, and ceasing the evaluation of the conditional handover measurement associated with the conditional handover configuration, and whether the measurement satisfies the conditional handover criteria.

[0252] Embodiment 14: An apparatus comprising at least one means for carrying out any of the methods of Embodiments 1 to 13.

[0253] Embodiment 15: A device for wireless communication comprising a processor, a memory communicating electronically with the processor, and instructions stored in the memory that can be executed by the processor to cause the device to perform any of the methods of Embodiments 1 to 13.

[0254] Embodiment 16: A non-temporary computer-readable medium for storing code for wireless communication, wherein the code comprises instructions that can be executed by a processor to perform any of the methods of Embodiments 1 to 13.

[0255] Embodiment 17: A method for wireless communication in user equipment (UE), comprising: receiving from a source base station a conditional handover configuration representing one or more conditional handover configurations associated with one or more target base stations, each of which includes a trigger measurement threshold for initiating a conditional handover to an associated target base station and a deconfiguration measurement threshold for deconfiguring a conditional handover configuration of an associated target base station; determining, at least in part, that a first deconfiguration measurement threshold for deconfiguring a first conditional handover configuration of a first target base station is met; and releasing the first conditional handover configuration of the first target base station.

[0256] Embodiment 18: The method of Embodiment 17, further comprising determining, at least in part, based on a conditional handover configuration, that a second trigger measurement threshold for initiating a handover to a second target base station is met, and sending a random access request to the second target base station, at least in part, based on a second conditional handover configuration of the second target base station, in order to initiate a random access procedure for a handover to the second target base station.

[0257] Embodiment 19: The method of Embodiment 17 or 18, wherein releasing the first conditional handover configuration comprises removing one or more of the radio resource control configuration, the first measurement, and the reporting configurations for the conditional handover trigger and the conditional handover deconfiguration trigger, or one or more timers associated with the first target base station, which are provided within the first conditional handover configuration, and ceasing to evaluate the conditional handover measurement associated with the first target base station and whether the measurement satisfies the conditional handover criterion or the conditional handover deconfiguration criterion.

[0258] Embodiment 20: Any method of Embodiments 17 to 19, further comprising transmitting a measurement report to the source base station indicating that the first conditional handover configuration of the first target base station is released.

[0259] Embodiment 21: Any method from Embodiments 17 to 20, wherein the measurement report further includes a deconfiguration instruction for the first target base station.

[0260] Embodiment 22: Any method from Embodiments 17 to 21, wherein the first deconfiguration measurement threshold is a channel quality threshold associated with a first target base station, and the first conditional handover configuration is released in response to the channel quality measurement of the first target base station being less than the channel quality threshold.

[0261] Embodiment 23: Any method of Embodiments 17 to 22, wherein a first deconfiguration measurement threshold comprises a first threshold related to a source base station and a second threshold related to a first target base station, and a first conditional handover configuration is released in response to a first channel quality measurement of the source base station exceeding the first threshold and a second channel quality measurement of the first target base station being less than the second threshold.

[0262] Embodiment 24: Any method of Embodiments 17 to 23, wherein the first deconfiguration measurement threshold is a differential threshold, and the first conditional handover configuration is released in response to the difference in channel quality measurements between the source base station and the first target base station exceeding the differential threshold.

[0263] Embodiment 25: An apparatus comprising at least one means for carrying out any of the methods of Embodiments 17 to 24.

[0264] Embodiment 26: A device for wireless communication comprising a processor, a memory communicating electronically with the processor, and instructions stored in the memory that can be executed by the processor to cause the device to perform any of the methods of Embodiments 17 to 24.

[0265] Embodiment 27: A non-temporary computer-readable medium for storing code for wireless communication, wherein the code comprises instructions that can be executed by a processor to perform any of the methods of Embodiments 17 to 24.

[0266] Embodiment 28: A method for wireless communication at a source base station, comprising: establishing one or more conditional handover configurations with each target base station for conditional handover of user equipment (UE) from a source base station to one or more target base stations, wherein each conditional handover configuration includes an validity period during which the conditional handover configuration is valid, and a conditional handover time period for completing a random access procedure when a conditional handover of the UE from the source base station to each target base station is initiated; and transmitting one or more conditional handover configurations to the UE, each indicating the associated target base station, one or more measurement thresholds for initiating a handover of the UE from the source base station to the associated target base station, and the associated target base station's conditional handover time period.

[0267] Embodiment 29: The method of Embodiment 28, further comprising deconfiguring the first conditional handover configuration of the first target base station in response to the expiration of a first validity period associated with the first target base station.

[0268] Embodiment 30: The method of Embodiment 28 or 29, wherein the UE autonomously deconfigures the first conditional handover configuration of the first target base station based on the expiration of a first validity period.

[0269] Embodiment 31: Any of Embodiments 28 to 30, wherein each of one or more target base stations has different values ​​for one or more of the validity period or conditional handover period.

[0270] Embodiment 32: Any method of Embodiments 28 to 31, wherein one or more of the validity time period or conditional handover time period is determined at least in part on one or more of the following: an estimate of the movement of the UE to each target base station, the traffic load of the source base station or each target base station, channel quality measurements to each target base station provided by the UE, or any combination thereof.

[0271] Embodiment 33: An apparatus comprising at least one means for carrying out any of the methods of Embodiments 28 to 32.

[0272] Embodiment 34: A device for wireless communication comprising a processor, a memory communicating electronically with the processor, and instructions stored in the memory that can be executed by the processor to cause the device to perform any of the methods of Embodiments 28 to 32.

[0273] Embodiment 35: A non-temporary computer-readable medium for storing code for wireless communication, wherein the code comprises instructions that can be executed by a processor to perform any of the methods of Embodiments 28 to 32.

[0274] Embodiment 36: A method for wireless communication at a source base station, comprising: establishing one or more conditional handover configurations with each target base station for conditional handover of user equipment (UE) from a source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating a conditional handover of the UE to the associated target base station and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station; and transmitting one or more conditional handover configurations to the UE, each indicating the associated target base station, the trigger measurement threshold for initiating a conditional handover to the associated target base station, and the conditional handover timer value for completing the conditional handover of the UE to the associated target base station.

[0275] Embodiment 37: The method of Embodiment 36, further comprising: determining in the UE that at least one first conditional handover configuration should be deconfigured; transmitting deconfiguration information to the UE indicating that in response to the decision to deconfigure, the UE should remove one or more of the radio resource control configuration, or a first measurement, and reporting configurations for the first conditional handover configuration; receiving a measurement report from the UE indicating that a first deconfiguration measurement threshold for deconfiguring the first conditional handover configuration of a first target base station is met; and releasing the first conditional handover configuration of the first target base station in response to the measurement report.

[0276] Embodiment 38: The method of Embodiment 36 or 37, wherein releasing the first conditional handover configuration comprises removing one or more of the radio resource control configuration, the first deconfiguration measurement threshold, the first trigger measurement threshold, or one or more timers associated with the first target base station that are included in the first conditional handover configuration.

[0277] Embodiment 39: The method according to any one of Embodiments 36 to 38, further comprising providing an instruction that the first conditional handover configuration is released to the first target base station to release the first conditional handover configuration.

[0278] Embodiment 40: The method according to any one of Embodiments 36 to 39, wherein the configuration release measurement threshold is a channel quality threshold related to each respective target base station, and the conditional handover configuration of the first target base station is released in response to the channel quality measurement value of the first target base station being less than the channel quality threshold of the first target base station.

[0279] Embodiment 41: The method according to any one of Embodiments 36 to 40, wherein the configuration release measurement threshold includes a first threshold related to the source base station and a second threshold for each respective target base station, and the conditional handover configuration of the first target base station is released in response to the first channel quality measurement value of the source base station exceeding the first threshold and the second channel quality measurement value of the first target base station being less than the second threshold of the first target base station.

[0280] Embodiment 42: The method according to any one of Embodiments 36 to 41, wherein the configuration release measurement threshold is a difference threshold, and the conditional handover configuration related to the first target base station is released in response to the difference in the channel quality measurement values between the source base station and the first target base station exceeding the difference threshold.

[0281] Embodiment 43: An apparatus comprising at least one means for performing the method according to any one of Embodiments 36 to 42.

[0282] [[ID=二十]]Embodiment 44: An apparatus for wireless communication, comprising a processor, a memory in electronic communication with the processor, and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to any one of Embodiments 36 to 42.

[0283] Embodiment 45: A non-temporary computer-readable medium for storing code for wireless communication, wherein the code comprises instructions that can be executed by a processor to perform any of the methods of Embodiments 36 to 42.

[0284] The techniques described herein can be used for a variety of wireless communication systems, including Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and other systems. CDMA systems may implement radio technologies such as CDMA2000 and Universal Terrestrial Radio Access (UTRA). CDMA2000 covers the IS-2000, IS-95, and IS-856 standards. IS-2000 releases are sometimes referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is sometimes referred to as CDMA2000 1xEV-DO, High-Speed ​​Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA®) and other variations of CDMA. TDMA systems may implement radio technologies such as the Global System for Mobile Communications (GSM).

[0285] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Advanced UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from an organization called the "Third Generation Partnership Project" (3GPP®). CDMA2000 and UMB are described in documents from an organization called the "Third Generation Partnership Project 2" (3GPP2). The techniques described herein may be used for the systems and radio technologies described herein as well as for other systems and radio technologies. Embodiments of LTE, LTE-A, LTE-A Pro, or NR systems may be described as examples, and the terms LTE, LTE-A, LTE-A Pro, or NR may be used for the majority of the description; however, the techniques described herein are applicable to applications other than those of LTE, LTE-A, LTE-A Pro, or NR.

[0286] Macrocells generally cover relatively large geographical areas (e.g., a radius of several kilometers) and can enable unrestricted access by UEs (User Entities) subscribed to a network provider's service. Small cells may be associated with lower-power base stations compared to macrocells and may operate in the same or different frequency bands as macrocells (e.g., licensed frequency bands, unlicensed frequency bands, etc.). Small cells may include picocells, femtocells, and microcells, depending on various examples. Picocells may cover small geographical areas, for example, and can enable unrestricted access by UEs subscribed to a network provider's service. Femtocells may also cover small geographical areas (e.g., a home) and can provide limited access by UEs associated with femtocells (e.g., UEs in a limited subscriber group (CSG), UEs for users in a home, etc.). eNBs for macrocells are sometimes called macro eNBs. eNBs for small cells are sometimes called small cell eNBs, pico eNBs, femto eNBs, or home eNBs. eNBs may support one or more cells (for example, two, three, or four) and may also support communications using one or more component carriers.

[0287] The wireless communication systems described herein may support synchronous or asynchronous operation. In synchronous operation, base stations may have similar frame timings, and transmissions from different base stations may be approximately time-synchronized. In asynchronous operation, base stations may have different frame timings, and transmissions from different base stations may not be time-synchronized. The techniques described herein may be used for either synchronous or asynchronous operation.

[0288] The information and signals described herein may be represented using any of the various different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout this description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof.

[0289] The various exemplary blocks and modules described in relation to the disclosure herein may be implemented or run using general-purpose processors, DSPs, ASICs, FPGAs or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working with a DSP core, or any other such configuration).

[0290] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. When implemented in software executed by a processor, the functions may be stored on or transmitted via computer-readable media as one or more instructions or codes. Other examples and implementations fall within the scope of this disclosure and the accompanying claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed so that parts of the functions are implemented in different physical locations.

[0291] Computer-readable media include both non-temporary computer storage media and communication media, including any media that facilitates the transfer of computer programs from one location to another. Non-temporary storage media may be any available media that can be accessed by a general-purpose computer or a dedicated computer. Examples, but not limitations, of non-temporary computer-readable media may include random-access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-temporary media that can be used to carry or store desired program code means in the form of instructions or data structures, and that can be accessed by a general-purpose computer or a dedicated computer or a general-purpose processor or a dedicated processor. Any connection is also appropriately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used herein, disk and disc include CD, LaserDisc®, OpticalDisc, Digital Multipurpose Disc (DVD)®, FloppyDisc, and Blu-ray® Disc, where disk typically reproduces data magnetically and disc optically using a laser. Combinations of the above are also included in the scope of computer-readable media.

[0292] When used herein, including within the claims, “or” as used in an enumeration of items (for example, an enumeration of items ending with a phrase such as “at least one of” or “one or more of”) indicates an inclusive enumeration, such as the enumeration “at least one of A, B, or C” meaning A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, the phrase “based on” as used herein should not be construed as a reference to a closed set of conditions. For example, an exemplary step described as “based on condition A” may be based on both condition A and condition B without departing from the scope of this disclosure. In other words, the phrase “based on” as used herein should be construed in the same way as the phrase “at least partially based on.”

[0293] In the attached diagrams, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a dash and a second label that distinguishes the similar components. If only the first reference label is used herein, the description is applicable to any of the similar components having the same first reference label, regardless of the second reference label or any other subsequent reference labels.

[0294] The descriptions provided herein with respect to the accompanying drawings are illustrative and do not necessarily represent all examples that may be implemented or fall within the scope of the claims. The term “exemplary” as used herein means “acting as an example, case, or illustration,” and does not mean “preferred” or “advantageous over other examples.” The modes for carrying out the invention include specific details to give rise to an understanding of the techniques described. However, these techniques may be practiced without these specific details. In some cases, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the examples described.

[0295] The description in this specification is provided to enable a person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Description of Reference Numerals

[0296] 100 Wireless communication system 105 Base station 110 Geographical coverage area 115 User equipment (UE) 125 Communication link 130 Core network 132, 134 Backhaul link 200 Wireless communication system 205 First communication connection 210 Second communication connection 215-a First CHO configuration 215-b Second CHO configuration 805 Device 810 Receiver 815 Communication manager 820 Transmitter 905 Device 910 Receiver 915 Communication manager 920 Handover configuration manager 925 Measurement manager 930 Random access manager 935 Conditional handover timer 940 Transmitter 1005 Communication manager 1010 Handover configuration manager 1015 Measurement manager 1020 Random access manager 1025 Conditional handover timer 1030 Effectiveness Timer 1035 RRC Connection Establishment Components 1105 devices 1110 Communications Manager 1115 I / O Controller 1120 Transceiver 1125 Antenna 1130 memory 1135 Code 1140 Processor 1145 Bus 1205 devices 1210 Receiver 1215 Communications Manager 1220 Transmitter 1305 devices 1310 Receiver 1315 Communications Manager 1320 Handover Configuration Manager 1325 UE Handover Manager 1330 Transmitter 1405 Communications Manager 1410 Handover Configuration Manager 1415 UE Handover Manager 1420 Timer Manager 1425 Measurement Manager 1505 Device 1510 Communications Manager 1515 Network Communications Manager 1520 Transceiver 1525 Antenna 1530 memory 1535 Computer-readable code, code 1540 processor 1545 Inter-station communications manager 1550 Bus

Claims

1. A method for wireless communication at a source base station, A step of establishing one or more conditional handover configurations with each target base station for a conditional handover of user equipment (UE) from the source base station to one or more target base stations, wherein each conditional handover configuration includes a trigger measurement threshold for initiating the conditional handover of the UE to the associated target base station, and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station. A step of transmitting one or more conditional handover configurations to the UE, each indicating the associated target base station, the trigger measurement threshold for initiating the conditional handover to the associated target base station, and the conditional handover timer value for completing the UE's conditional handover to the associated target base station, wherein the conditional handover timer value for completing the UE's conditional handover is the timer value for completing the UE's conditional handover random access procedure. A step of determining that at least a first conditional handover configuration should be deconfigured in the UE, the step being performed at least in part on a signal from the associated target base station, and A method for providing this.

2. In response to the decision to deconfigure, the UE transmits deconfiguration information to the UE indicating that it should remove one or more of the radio resource control configurations or the first measurement and reporting configurations for the first conditional handover configuration. The steps include releasing the first conditional handover configuration of the first target base station and The method according to claim 1, further comprising:

3. The step of releasing the first conditional handover configuration is, The further step includes providing the first target base station with an instruction that the first conditional handover configuration is released. The method according to claim 2.

4. The method according to claim 1, wherein a conditional handover configuration associated with a first target base station is released in response to the difference in channel quality measurements between the source base station and the first target base station exceeding a difference threshold.

5. The step of releasing the first conditional handover configuration is, The first conditional handover configuration includes the step of removing one or more of the following timers associated with the first target base station: a radio resource control configuration, a first trigger measurement threshold, or one or more timers associated with the first target base station. The method according to claim 2.

6. A device for wireless communication at a source base station, Processor and The memory coupled to the aforementioned processor, The device comprises instructions stored in the memory, and the instructions are transmitted to the device. For the conditional handover of user equipment (UE) from the source base station to one or more target base stations, the source base station establishes one or more conditional handover configurations with each target base station, wherein each conditional handover configuration includes a trigger measurement threshold for initiating the conditional handover of the UE to the associated target base station, and a conditional handover timer value for completing the conditional handover of the UE to the associated target base station. Transmitting one or more conditional handover configurations to the UE, each representing the associated target base station, the trigger measurement threshold for initiating the conditional handover to the associated target base station, and the conditional handover timer value for completing the UE's conditional handover to the associated target base station, wherein the conditional handover timer value for completing the UE's conditional handover is the timer value for completing the UE's conditional handover random access procedure. The UE decides to deconfigure at least a first conditional handover configuration, which is done at least in part on the signal from the associated target base station. A device that is executable by a processor in order to perform a certain action.

7. The command to the device, In response to the decision to deconfigure, the UE transmits deconfiguration information to the UE indicating that one or more of the radio resource control configuration or the first measurement and reporting configuration should be removed from the first conditional handover configuration, Releasing the first conditional handover configuration of the first target base station and The apparatus according to claim 6, further executable by the processor to perform the following actions.

8. The instruction to release the first conditional handover configuration causes the device to: The apparatus according to claim 7, further executable by the processor to cause the first target base station to provide an instruction that the first conditional handover configuration is released.

9. The apparatus according to claim 6, wherein a conditional handover configuration of a first target base station is released in response to a channel quality measurement of the first target base station being less than a channel quality threshold of the first target base station.

10. The apparatus according to claim 6, wherein a conditional handover configuration of a first target base station is released in response to a first channel quality measurement of the source base station exceeding a first threshold and a second channel quality measurement of the first target base station being less than a second threshold of the first target base station.

11. The apparatus according to claim 6, wherein a conditional handover configuration associated with a first target base station is released in response to the difference in channel quality measurements between the source base station and the first target base station exceeding a difference threshold.

12. The instruction to release the first conditional handover configuration causes the device to: The apparatus according to claim 7, further executable by the processor to remove one or more of the radio resource control configuration, the first trigger measurement threshold, or the one or more timers associated with the first target base station, which are included in the first conditional handover configuration.

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