Mobility enhancements for unlicensed operations

Abstract

This disclosure provides systems, methods, and devices for a user equipment (UE) to perform a listen before talk (LBT) procedure during handover, such as during dual active protocol stack (DAPS) handover or conditional handover. During handover, the UE may have a source connection with a source cell. If the source cell is unlicensed, the UE may perform LBT for a channel of the source cell. The UE may establish a target connection with a target cell prior to releasing the source connection with the source cell. If the target cell is unlicensed, the UE may perform LBT for a channel of the target cell.

Description

[0001] This application is a divisional application of an application with an application date of October 8, 2020, application number 202080077799.8 (international application number PCT / US2020 / 070632), and name “Mobility Enhancement for Unlicensed Operations”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims priority to U.S. Provisional Patent Application No. 62 / 945,021, filed on December 6, 2019, entitled “MOBILITY ENHANCEMENTS FOR UNLICENSED OPERATION,” and U.S. Non-Provisional Patent Application No. 16 / 948,947, filed on October 7, 2020, entitled “MOBILITY ENHANCEMENTS FOR UNLICENSEDOPERATION,” which are hereby expressly incorporated herein by reference. Technical Field

[0004] Aspects of the present disclosure relate generally to wireless communications, and more particularly to techniques for mobility enhancement for unlicensed operations. Background Art

[0005] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE / LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

[0006] A wireless communication network may include several base stations (BS) that can support communication of several user equipments (UEs). User equipments (UEs) may communicate with base stations (BSs) via downlinks (DL) and uplinks (UL). DL (or forward link) refers to the communication link from BS to UE, while UL (or reverse link) refers to the communication link from UE to BS. As will be described in more detail herein, a BS may be referred to as a B node, an LTE evolved B node (eNB), a gNB, an access point (AP), a radio head, a transmission reception point (TRP), a new radio (NR) BS, or a 5G B node.

[0007] The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different UEs to communicate at city, country, region, and even global levels. NR (which may also be referred to as 5G) is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with orthogonal frequency division multiplexing (OFDM) (CP-OFDM) with cyclic prefix (CP) on DL, CP-OFDM or SC-FDM (e.g., also referred to as discrete Fourier transform spread OFDM (DFT-s-OFDM) (or a combination thereof) on UL, and other open standards that support beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. Summary of the invention

[0008] One innovative aspect of the subject matter described in the present disclosure can be implemented in a method of wireless communication performed by a user equipment (UE). The method may include: determining that a handover of the UE from a source cell to a target cell is triggered, wherein the source cell is an unlicensed source cell; and performing listen before talk (LBT) on a channel of the source cell during the handover based on the determination and until a stop condition occurs.

[0009] In some implementations, the stop condition includes one or more of the following operations: completion of a random access channel procedure at the target cell, or receipt of a release source message from the target cell.

[0010] In some implementations, the target cell is an unlicensed target cell, and performing LBT during the handover includes: performing LBT on a channel of the target cell based on receiving a handover command message. In some implementations, the method may include performing one or more of the following operations based on detecting one or more LBT failures on the channel of the target cell: stopping the handover to the target cell, reporting the one or more LBT failures, or continuing to connect to the source cell.

[0011] In some implementations, the method may include performing one or more of the following operations based on detecting one or more LBT failures on the channel of the source cell: switching to another bandwidth portion at the source cell, or transmitting a random access channel message to the target cell. In some implementations, the method may include ceasing transmission and reception at the source cell based on detecting one or more LBT failures on the channel of the source cell. In some implementations, the method may include switching uplink data transmission to the target cell based on detecting one or more LBT failures on the channel of the source cell. In some implementations, the method may include reporting the one or more LBT failures to the target cell based on detecting one or more LBT failures on the channel of the source cell.

[0012] In some implementations, the handover is a dual active protocol stack (DAPS) handover from the source cell to the target cell. In some implementations, the handover is a conditional handover from the source cell to one of the target cell or another target cell. In some implementations, the target cell is an unlicensed candidate target cell, and performing LBT during the handover includes: performing LBT on a channel of the target cell and a channel of another unlicensed candidate target cell based on receiving a handover command message.

[0013] In some implementations, the method may include ceasing conditional handover to the target cell and attempting conditional handover to the other target cell based on detecting one or more LBT failures on a channel of the target cell. In some implementations, the method may include switching to another bandwidth portion at the target cell based on detecting one or more LBT failures on a channel of the target cell. In some implementations, the method may include reporting the one or more LBT failures to the source cell or the other target cell based on detecting one or more LBT failures on a channel of the target cell.

[0014] In some implementations, the channel is an uplink channel. In some implementations, the channel is a downlink channel.

[0015] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a UE for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine that a handover of the UE from a source cell to a target cell is triggered, wherein the source cell is an unlicensed source cell; and perform LBT on a channel of the source cell during the handover based on the determination and until a stop condition occurs.

[0016] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. When executed by one or more processors of a UE, the one or more instructions can cause the one or more processors to: determine that a handover of the UE from a source cell to a target cell is triggered, wherein the source cell is an unlicensed source cell; and perform LBT on a channel of the source cell based on the determination during the handover and until a stop condition occurs.

[0017] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: means for determining that a handover of a UE from a source cell to a target cell is triggered, wherein the source cell is an unlicensed source cell; and means for performing LBT on a channel of the source cell during the handover based on the determination and until a stop condition occurs.

[0018] One innovative aspect of the subject matter described in the present disclosure may be implemented in a method of wireless communication performed by a UE. The method may include: determining that a handover of the UE from a source cell to a target cell is triggered, wherein the target cell is an unlicensed target cell; and performing LBT on a channel of the target cell based on receiving a handover command message during the handover.

[0019] In some implementations, the method may include performing at least one of the following operations based on detecting one or more LBT failures on a channel of the target cell: stopping the handover to the target cell, reporting the one or more LBT failures, or continuing to connect to the source cell. In some implementations, the handover is a DAPS handover from the source cell to the target cell.

[0020] In some implementations, the handover is a conditional handover from the source cell to one of the target cell or another target cell. In some implementations, performing LBT during the handover includes performing LBT on a channel of the target cell and a channel of another unlicensed candidate target cell based on receiving a handover command message.

[0021] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a UE for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine that a handover of the UE from a source cell to a target cell is triggered, wherein the target cell is an unlicensed target cell; and perform LBT on a channel of the target cell based on receiving a handover command message during the handover.

[0022] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, can cause the one or more processors to: determine that a handover of the UE from a source cell to a target cell is triggered, wherein the target cell is an unlicensed target cell; and perform LBT on a channel of the target cell based on receiving a handover command message during the handover.

[0023] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: means for determining that a handover of a UE from a source cell to a target cell is triggered, wherein the target cell is an unlicensed target cell; and means for performing LBT on a channel of the target cell based on receiving a handover command message during the handover.

[0024] One innovative aspect of the subject matter described in the present disclosure may be implemented in a method of wireless communication performed by a UE. The method may include: determining that a handover of the UE from a source cell to a target cell is triggered; and detecting one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during the handover.

[0025] In some implementations, detecting the one or more LBT failures includes: detecting that one or more reference signals are not received from one or more of the target cell or the source cell. In some implementations, the method may include performing one or more of the following operations based on detecting the one or more LBT failures on the channel of the source cell: switching to another bandwidth portion at the source cell, transmitting a random access channel message to the target cell, ceasing transmission and reception at the source cell, or switching uplink data transmission to the target cell. In some implementations, the method may include performing one or more of the following operations based on detecting the one or more LBT failures on the channel of the target cell: ceasing the handover to the target cell, reporting the one or more LBT failures, or continuing to connect to the source cell.

[0026] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a UE for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine that a handover of the UE from a source cell to a target cell is triggered; and detect one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during the handover.

[0027] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, can cause the one or more processors to: determine that a handover of the UE from a source cell to a target cell is triggered; and detect one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during the handover.

[0028] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: means for determining that a handover of a UE from a source cell to a target cell is triggered; and means for detecting one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during the handover.

[0029] One innovative aspect of the subject matter described in the present disclosure may be implemented in a method of wireless communication performed by a UE. The method may include determining that a secondary node (SN) change of the UE is triggered, and performing LBT on one or more of a channel of an unlicensed source secondary cell or a channel of an unlicensed target secondary cell during the SN change.

[0030] In some implementations, the method may include: performing LBT during the SN change includes performing LBT on a channel of the unlicensed source secondary cell based on the determination and until a stop condition occurs. In some implementations, the stop condition includes one or more of the following operations: completing a random access channel procedure at the unlicensed target secondary cell, or receiving a release source message from the unlicensed target secondary cell. In some implementations, the method may include performing one or more of the following operations based on detecting one or more LBT failures on the channel of the unlicensed source secondary cell: switching to another bandwidth portion at the unlicensed source secondary cell, transmitting a random access channel message to the unlicensed target secondary cell, or reporting the one or more LBT failures to an associated primary cell.

[0031] In some implementations, performing LBT during the SN change includes performing LBT on a channel of the unlicensed target secondary cell based on receiving an SN change message.

[0032] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a UE for wireless communication. The UE may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine that an SN change of the UE is triggered, and perform LBT on one or more of a channel of an unlicensed source secondary cell or a channel of an unlicensed target secondary cell during the SN change.

[0033] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, can cause the one or more processors to: determine that an SN change of the UE is triggered, and perform LBT on one or more of a channel of an unlicensed source secondary cell or a channel of an unlicensed target secondary cell during the SN change.

[0034] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication. The apparatus may include: means for determining that an SN change of a UE is triggered, and means for performing LBT on one or more of a channel of an unlicensed source secondary cell or a channel of an unlicensed target secondary cell during the SN change.

[0035] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a method of wireless communication performed by a device of a base station, the method comprising: triggering a handover of a UE, receiving one or more LBT failure reports from the UE during the handover, and performing an action for the UE based on the one or more LBT failure reports.

[0036] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a method of wireless communication performed by a device of a base station, the method comprising: triggering a change of the SN of a secondary cell group, receiving one or more LBT failure reports from a UE during the change, and performing an action for the UE based on the one or more LBT failure reports.

[0037] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a base station for wireless communication. The base station may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: trigger a handover of a UE, obtain one or more LBT failure reports from the UE via an interface during the handover, and perform an action for the UE based on the one or more LBT failure reports. In some implementations, the memory and the one or more processors may be configured to: discard a source cell or a target cell for the UE.

[0038] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a base station for wireless communication. The base station may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: trigger a change in the SN of a secondary cell group, obtain one or more LBT failure reports from a UE via an interface during the change, and perform an action for the UE based on the one or more LBT failure reports. In some implementations, the memory and the one or more processors may be configured to: discard a secondary cell for the UE.

[0039] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a base station, can cause the one or more processors to: trigger a handover of a UE, receive one or more LBT failure reports from the UE during the handover, and perform an action for the UE based on the one or more LBT failure reports.

[0040] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium. The non-transitory computer-readable medium can store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a base station, can cause the one or more processors to: trigger a change in the SN of a secondary cell group, receive one or more LBT failure reports from a UE during the change, and perform an action for the UE based on the one or more LBT failure reports.

[0041] In some aspects, an apparatus for wireless communication includes: a device for triggering a handover of a UE, a device for receiving one or more LBT failure reports from the UE during the handover, and a device for performing an action for the UE based on the one or more LBT failure reports.

[0042] In some aspects, an apparatus for wireless communication includes: a device for triggering a change of the SN of a secondary cell group, a device for receiving one or more LBT failure reports from a UE during the change, and a device for performing an action for the UE based on the one or more LBT failure reports.

[0043] Aspects generally include methods, apparatus, systems, computer program products, non-transitory computer readable media, user equipment, base stations, wireless communication devices, or processing systems, substantially as described herein with reference to and as illustrated by the accompanying drawings.

[0044] Details of one or more implementations of the subject matter described in the present disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. It should be noted that the relative sizes of the following drawings may not be drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a block diagram conceptually illustrating an example of a wireless network.

[0046] Figure 2 is a block diagram conceptually illustrating an example of a base station and a user equipment (UE) in communication in a wireless network.

[0047] Figure 3 is a diagram illustrating an example in which a UE performs listen-before-talk (LBT) during handover.

[0048] Figure 4 is a diagram illustrating an example in which a UE performs LBT during handover.

[0049] Figure 5 is a diagram illustrating an example in which a UE performs LBT during handover.

[0050] Figure 6 is a diagram illustrating an example in which a UE performs LBT during DAPS switching.

[0051] Figure 7 is a diagram illustrating an example in which a UE performs LBT during conditional switching.

[0052] Figure 8 is a diagram illustrating an example process performed, for example, by a UE.

[0053] Fig. 9 is a diagram illustrating an example process performed, for example, by a UE.

[0054] Fig.10 is a diagram illustrating an example process performed, for example, by a UE.

[0055] Fig.11 is a diagram illustrating an example process performed, for example, by a UE.

[0056] Fig.12 is a diagram illustrating an example process performed, for example, by a base station.

[0057] Fig.13 is a diagram illustrating an example process performed, for example, by a base station.

[0058] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION

[0059] The following description is directed to certain implementations in order to describe the innovative aspects of the present disclosure. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in many different ways. Some examples in the present disclosure are based on wireless and wired local area network (LAN) communications in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless standards, the IEEE 802.3 Ethernet standards, and the IEEE 1901 Power Line Communication (PLC) standards. However, the described implementations can be implemented in any device, system, or network capable of transmitting and receiving radio frequency signals in accordance with any of the following wireless communication protocols: including any of the IEEE 802.11 standards, (Bluetooth) standard, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), global system for mobile communications (GSM), GSM / general packet radio service (GPRS), enhanced data GSM environment (EDGE), terrestrial trunked radio (TETRA), wideband CDMA (W-CDMA), evolution data optimized (EV-DO), 1xEV-DO, EV-DO Revision A, EV-DO Revision B, high speed packet access (HSPA), high speed downlink packet access (HSDPA), high speed uplink packet access (HSUPA), evolved high speed packet access (HSPA+), long term evolution (LTE), AMPS, or other known signals for communication within a wireless network, cellular network, or Internet of Things (IoT) network (such as, a system utilizing 3G, 4G or 5G or further implementations thereof).

[0060] A wireless network may support radio access technologies and may operate on one or more frequencies, which may also be referred to as carriers or frequency channels. Some carriers used for wireless communications are licensed carriers. Cellular networks, such as LTE networks or 5G networks, may use licensed carriers. Wireless local area networks or Wi-Fi networks may use unlicensed carriers. 5G networks may utilize licensed assisted access (LAA), which utilizes unlicensed carriers in combination with licensed carriers to improve the performance of UEs.

[0061] Transmissions on unlicensed carriers may require a transmitting device (such as a UE) to determine whether the carrier (frequency channel) is clear for transmission. Listen before talk or (Listen before Transmit, LBT) is a mechanism that a UE can use to listen to whether a channel is clear. If the UE performs LBT on a channel and the channel is clear, this may be referred to as LBT success. If the UE performs LBT on a channel and the channel is not clear, this may be referred to as LBT failure.

[0062] UE mobility may involve the UE moving from a source cell (e.g., a source base station) to a target cell (e.g., a target base station). Accordingly, the UE's connection may be moved from the source cell to the target cell using a procedure known as handover. Although service interruption may occur when performing a handover, enhancements to UE mobility may alleviate such interruptions. One mobility enhancement is dual active protocol stack (DAPS) handover. DAPS handover may reduce or eliminate service interruption during handover. The interruption may be reduced because the UE may maintain both the source connection to the source cell and the target connection to the target cell during the handover. This type of handover may be considered a build-before-break (MBB) handover. Another mobility enhancement is conditional handover, in which the UE may identify candidate target cells and corresponding conditions that will control when the UE is to be switched and to which candidate target cell it is to be switched. Upon triggering a measurement condition, the UE may complete a handover to a candidate target cell that has satisfied the corresponding condition.

[0063] DAPS switching and conditional switching have focused on licensed carriers. However, DAPS switching and conditional switching can be extended to unlicensed carriers because 5G networks can utilize (including simultaneously utilizing) both licensed and unlicensed carriers. In the case of utilizing an unlicensed carrier, the UE can perform LBT for uplink transmissions and transmit after the LBT is successful. For unlicensed carriers, the DAPS switching process is still under development. DAPS switching may include unlicensed carriers, and unlicensed carriers involve LBT procedures for determining whether a channel is clear for transmitting signals on the channel. The UE may be switched to a target cell that may suffer an LBT failure and may not be able to transmit an uplink signal. This will result in poor service, waiting time, and additional processing, and signaling resources may be used to rebuild a connection back to the source cell or to another cell.

[0064] In various aspects described herein, a UE may perform LBT during a handover (such as during a DAPS handover or a conditional handover). During the handover, the UE may have a source connection with a source cell (e.g., a source base station). If the source cell is unlicensed, the UE may perform LBT for one channel (or for more than one channel) of the source cell. The UE may establish a target connection with a target cell (e.g., a target base station) before releasing the source connection with the source cell. If the target cell is unlicensed, the UE may perform LBT for one channel (or for more than one channel) of the target cell. In this way, the UE may perform LBT during a handover with little or no service interruption. Depending on whether the UE detects LBT success or LBT failure at the source cell or the target cell during the handover, the UE may take appropriate actions to switch to a target cell that may be unlicensed, cancel the handover to the target cell, or select a different target cell. Because the UE may make a handover determination during the handover, the UE may prevent the completion of a handover to an unlicensed cell that may result in a LBT failure.

[0065] Certain implementations of the subject matter described in this disclosure may be implemented to achieve one or more potential advantages. For example, a UE may not suffer latency and performance loss due to a DAPS handover or conditional handover. Processing and signaling resources are not wasted to reestablish a connection to a cell that does not cause LBT failure to an unlicensed cell.

[0066] Figure 1 1 is a block diagram conceptually illustrating an example of a wireless network 100. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include several BSs 110 (shown as BSs 110a, BSs 110b, BSs 110c, and BSs 110d) and other network entities. A BS is an entity that communicates with a user equipment (UE) and may also be referred to as a base station, NR BS, B node, gNB, 5G B node (NB), access point, or transmit receive point (TRP). Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to a coverage area of ​​a BS or a BS subsystem serving the coverage area, or a combination thereof, depending on the context in which the term is used.

[0067] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, another type of cell, or a combination thereof. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1 In the example shown in , BS 110a may be a macro BS for macro cell 102a, BS 110b may be a pico BS for pico cell 102b, and BS 110c may be a femto BS for femto cell 102c. The BS may support one or more (e.g., three) cells. The terms "eNB", "base station", "NR BS", "gNB", "TRP", "AP", "B node", "5G NB", and "cell" may be used interchangeably herein.

[0068] In some examples, the cell may not necessarily be stationary, and the geographic area of ​​the cell may move depending on the location of the mobile BS. In some examples, the BSs may be interconnected to each other and to one or more other BSs or network nodes (not shown) in the wireless network 100 via various types of backhaul interfaces, such as direct physical connections, virtual networks, or combinations thereof using any suitable transport networks.

[0069] The wireless network 100 may also include a relay station. A relay station is an entity that can receive transmissions of data from an upstream station (e.g., a BS or a UE) and send transmissions of the data to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that can relay transmissions for other UEs. Figure 1 In the example shown in , a relay station 110d may communicate with a macro BS 110a and a UE 120d to facilitate communication between the BS 110a and the UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, or the like.

[0070] The wireless network 100 may be a heterogeneous network including different types of BSs (e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different effects on interference in the wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 5 to 40 watts), while a pico BS, a femto BS, and a relay BS may have a lower transmit power level (e.g., 0.1 to 2 watts).

[0071] The network controller 130 may be coupled to a set of BSs and may provide coordination and control of these BSs. The network controller 130 may communicate with each BS via a backhaul. The BSs may also communicate with each other directly or indirectly, for example, via a wireless or wired backhaul.

[0072] UE 120 (e.g., 120a, 120b, 120c) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. UE may also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, etc. UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle-mounted component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium.

[0073] Some UEs may be considered as machine type communication (MTC) UEs, or evolved or enhanced machine type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which may communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide connectivity to or to a network (e.g., a wide area network (such as the Internet) or a cellular network), for example, via a wired or wireless communication link. Some UEs may be considered as Internet of Things (IoT) devices, or may be implemented as NB-IoT (narrowband Internet of Things) devices. Some UEs may be considered as client equipment (CPE). UE 120 may be included inside a housing that houses components of UE 120, such as a processor component, a memory component, a similar component, or a combination thereof.

[0074] In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a specific RAT and may operate on one or more frequencies. RAT may also be referred to as radio technology, air interface, etc. Frequency may also be referred to as carrier, frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

[0075] In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within a service area or cell of the scheduling entity. Within the present disclosure, as discussed further below, a scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, the subordinate entities utilize resources allocated by the scheduling entity.

[0076] The base station is not the only entity that can be used as a scheduling entity. That is, in some examples, a UE can be used as a scheduling entity, thereby scheduling resources for one or more subordinate entities (e.g., one or more other UEs). In this example, the UE is acting as a scheduling entity, and other UEs use the resources scheduled by the UE for wireless communication. The UE can be used as a scheduling entity in a peer-to-peer (P2P) network, in a mesh network, or in another type of network. In the mesh network example, the UEs can optionally communicate directly with each other in addition to communicating with the scheduling entity.

[0077] Thus, in a wireless communication network having scheduled access to time-frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate using the scheduled resources.

[0078] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly (e.g., without using base station 110 as an intermediary to communicate with each other) using one or more sidelink channels. For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, or similar protocols), mesh networks, or similar networks, or a combination thereof. In this case, UE 120 may perform scheduling operations, resource selection operations, and other operations described elsewhere herein as being performed by base station 110.

[0079] Figure 22 is a block diagram conceptually illustrating an example 200 of a base station 110 and a UE 120 in communication. In some aspects, the base station 110 and the UE 120 may be, respectively. Figure 1 One of the base stations and one of the UEs in the wireless network 100. The base station 110 may be equipped with T antennas 234a through 234t, and the UE 120 may be equipped with R antennas 252a through 252r, where in general T≥1 and R≥1.

[0080] At the base station 110, the transmit processor 220 may receive data for one or more UEs from the data source 212, select one or more modulation and coding schemes (MCS) for each UE based on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for each UE based on the MCS selected for the UE, and provide data symbols for all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, overhead symbols, or reference symbols, where applicable, and may provide T output symbol streams to T modulators (MOD) 232a to 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., switch to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a to 232t may be transmitted via T antennas 234a to 234t, respectively. According to various aspects described in more detail below, position coding may be used to generate synchronization signals to convey additional information.

[0081] At UE 120, antennas 252a to 252r may receive downlink signals from base station 110 or other base stations and may provide received signals to demodulators (DEMODs) 254a to 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols where applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller or processor (controller / processor) 280. The channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of UE 120 may be included in a housing.

[0082] On the uplink, at the UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266, if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, uplink signals from the UE 120 and other UEs may be received by the antenna 234, processed by the demodulator 232, detected by the MIMO detector 236, if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide decoded data to a data sink 239 and provide decoded control information to a controller or processor (i.e., controller / processor) 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller or processor (i.e., controller / processor) 290, and a memory 292.

[0083] In some implementations, the controller / processor 280 may be a component of a processing system. A processing system may generally refer to a system or series of machines or components that receives inputs and processes those inputs to produce a set of outputs that may be passed to other systems or components such as the UE 120. For example, a processing system of the UE 120 may refer to a system that includes various other components or subcomponents of the UE 120.

[0084] The processing system of UE 120 can be interfaced with other components of UE 120, and can process information (such as input or signal) received from other components, output information to other components, etc. For example, a chip or modem of UE 120 may include a processing system, a first interface configured to receive or obtain information, and a second interface configured to output, transmit or provide information. In some cases, the first interface may refer to an interface between the processing system of the chip or modem and a receiver, so that UE 120 can receive information or signal input, and the information can be passed to the processing system. In some cases, the second interface may refer to an interface between the processing system of the chip or modem and a transmitter, so that UE 120 can transmit information output from the chip or modem. The second interface may also obtain or receive information or signal input, and the first interface may also output, transmit or provide information.

[0085] In some implementations, controller / processor 240 may be a component of a processing system. A processing system may generally refer to a system or series of machines or components that receive inputs and process those inputs to produce a set of outputs that may be delivered to other systems or components such as BS 110. For example, a processing system of BS 110 may refer to a system that includes various other components or subcomponents of BS 110.

[0086] The processing system of BS110 can be docked with other components of BS110, and can process information (such as input or signal) received from other components, output information to other components, etc. For example, the chip or modem of BS110 may include a processing system, a first interface configured to receive or obtain information, and a second interface configured to output, transmit or provide information. In some cases, the first interface may refer to an interface between the processing system of the chip or modem and a receiver, so that BS110 can receive information or signal input, and the information can be passed to the processing system. In some cases, the second interface may refer to an interface between the processing system of the chip or modem and a transmitter, so that BS110 can transmit information output from the chip or modem. The second interface can also obtain or receive information or signal input, and the first interface can also output, transmit or provide information.

[0087] Figure 2The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, or any other component(s) may perform one or more techniques associated with mobility enhancement for unlicensed operation, as described in more detail elsewhere herein. For example, Figure 2 The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, or any other component (or combination of components) may perform or direct the operation of, for example, the following processes: Figure 8 The process of 800 Fig. 9 The process of 900 Fig.10 The process of 1000 Fig.11 Process 1100, Fig.12 The process 1200 Fig.13 Memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively. Scheduler 246 may schedule UEs for data transmission on the downlink or uplink, or a combination thereof.

[0088] The stored program codes, when executed by the controller / processor 280 or other processors and modules at the UE 120, may cause the UE 120 to perform operations described with respect to the following processes: Figure 8 The process of 800 Fig. 9 The process of 900 Fig.10 The process of 1000 Fig.11 Process 1100, Fig.12 The process 1200 Fig.13 1300, or other processes as described herein.

[0089] In some aspects, UE 120 may include: means for determining that a handover of the UE from a source cell to a target cell is triggered, wherein the source cell is an unlicensed source cell; and means for performing LBT on a channel of the source cell during the handover based on the determination and until a stop condition occurs; or a combination thereof. In some aspects, such means may include in conjunction with Figure 2 One or more components of UE 120 are described.

[0090] In some aspects, UE 120 may include: means for determining that a handover of the UE from a source cell to a target cell is triggered, wherein the target cell is an unlicensed target cell; and means for performing LBT on a channel of the target cell based on receiving a handover command message during the handover; or a combination thereof. In some aspects, such means may include in conjunction with Figure 2 One or more components of UE 120 are described.

[0091] In some aspects, UE 120 may include: means for determining that a handover of the UE from a source cell to a target cell is triggered; and means for detecting one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during the handover; or a combination thereof. In some aspects, such means may include in conjunction with Figure 2 One or more components of UE 120 are described.

[0092] In some aspects, UE 120 may include: means for determining that an SN change of the UE is triggered; and means for performing LBT on one or more of a channel of an unlicensed source secondary cell or a channel of an unlicensed target secondary cell during the SN change; or a combination thereof. In some aspects, such means may include a combination of Figure 2 One or more components of UE 120 are described.

[0093] In some aspects, the base station 110 may include: means for triggering a handover of the UE; means for receiving one or more LBT failure reports from the UE during the handover; means for performing an action for the UE based on the one or more LBT failure reports; or a combination thereof. In some aspects, such means may include in conjunction with Figure 2 One or more components of base station 110 are described.

[0094] In some aspects, the base station 110 may include: means for triggering a change in the SN of the secondary cell group; means for receiving one or more LBT failure reports from the UE during the change; means for performing an action for the UE based on the one or more LBT failure reports; or a combination thereof. In some aspects, such means may include in conjunction with Figure 2 One or more components of base station 110 are described.

[0095] although Figure 2 The blocks in the 200 and 210 are illustrated as distinct components, but the functions described above with respect to these blocks may be implemented with a single hardware, software, or combined component or various combinations of components. For example, the functions described with respect to the transmit processor 264, the receive processor 258, the TX MIMO processor 266, or another processor may be performed by or under the control of the controller / processor 280.

[0096] Figure 3 3 is a diagram illustrating an example 300 of a UE performing LBT during handover. A source BS 310 (such as in Figure 1 BS110a–110d depicted and described in Figure 21 and described in the BS 110) may provide for UE 320 (such as in Figure 1 UEs 120a-120e depicted and described in Figure 2 UE 320 may be handed over from the source cell to a target cell provided by a target BS 330 (such as BSs 110a-110d and BS 110).

[0097] As indicated by reference numeral 340, the UE 320 may determine that a handover is triggered. For example, the UE 320 may receive a handover command or a reconfiguration message from the source BS 310. The source BS 310 may provide the message to the UE 320 after receiving a corresponding message from the target BS 330. In some aspects, the message from the source BS 310 may be related to causing a DAPS handover. In some aspects, the message may be related to causing a conditional handover, wherein the message may identify a candidate target BS and corresponding conditions that will control when the UE 320 is to be handed over and to which candidate target BSs it is to be handed over. Additionally or alternatively, the handover may be triggered by determining that measurements are to be performed on signals of the source cell or one or more target cells.

[0098] As shown in reference numeral 342, UE 320 may perform LBT on channels that UE 320 may use to transmit uplink signals to source BS 310 or receive downlink signals from source BS 310 during handover. For example, if the source cell is an unlicensed source cell, UE 320 may listen or monitor any signal power on a specific channel to or from source BS 310. In some aspects, UE 320 may perform LBT on a wideband channel (e.g., greater than 20 MHz wide). A wideband channel may include multiple channels or subchannels. In some aspects, such as for unlicensed millimeter wave (mm wave) bands, UE 320 may use receive beamforming to monitor the channel from a specific direction. When LBT has a successful result for a specific direction, UE 320 may determine a beam set to transmit using the specific direction. Alternatively, during the LBT procedure, UE 320 may perform a pseudo-omnidirectional LBT procedure to monitor the channel from multiple directions.

[0099] Figure 434 is a diagram illustrating an example 300 in which a UE 320 performs LBT during a handover. As indicated by reference numeral 344, the UE 320 may receive a message regarding a target cell. The message may be a radio resource control (RRC) reconfiguration message or another message indicating a handover to the target BS 330. As indicated by reference numeral 346, if the target cell is an unlicensed cell, the UE 320 may perform LBT on a channel of the target cell during the handover. The UE 320 may establish a target connection with the target cell before releasing the source connection with the source cell. This may provide uninterrupted service while the source connection is released. In some aspects, the UE 320 may perform LBT on a channel (or more than one channel) of the source cell and a channel (or more than one channel) of the target cell simultaneously.

[0100] Figure 5 34 is a diagram illustrating an example 300 of a UE 320 performing LBT during a handover. As indicated by reference numeral 348, the UE 320 may stop performing LBT on a channel of a source cell based on a stop condition. The stop condition may include receiving a release source message. The UE 320 may receive a release source message from a target cell. The UE 320 may release a source connection to the source cell. For example, the UE 320 may release the source connection after successfully accessing the target BS 330 and establishing a target connection with the target BS 330. If the attempt to access the target BS 330 fails, the UE 320 may maintain the source connection with the source cell.

[0101] In some aspects, the stopping condition may be completion of a random access channel (RACH) procedure at the target cell. If the RACH procedure is successful when accessing the target cell, the RACH procedure may be completed.

[0102] While the UE 320 may stop performing LBT on the channels of the source cell, the UE 320 may continue to perform LBT on the channels of the target cell. In some aspects, the UE 320 may perform LBT on the channels of the target cell as long as the UE 320 maintains the target connection to the target cell.

[0103] Figure 6 600 is a diagram illustrating an example of a UE performing LBT during a DAPS handover. Figure 1 BS110a–110d depicted and described in Figure 2 BS 110 depicted and described in Figure 3 BS 310 depicted and described in Figure 1 UE 120a-120e depicted and described in Figure 2UE 120 depicted and described in Figure 3 The UE may be handed over from the source cell to a UE 320 depicted and described in the figure. The UE may be handed over from the source cell to a UE 320 represented and described in the figure. The UE may be handed over from the source cell to a UE 320 represented and described in the figure. Figure 3 The target cellular cell is provided by BS 330) depicted and described in FIG.

[0104] As indicated by reference numeral 610, the UE may perform LBT on a channel of the source cell during a DAPS handover. As indicated by reference numeral 620, the UE may perform LBT on a channel of the target cell during a DAPS handover. In some implementations, the UE may perform LBT on a channel of the source cell that starts (or continues) at the beginning of the DAPS handover and ends during the DAPS handover. The UE may perform LBT on a channel of the target cell that starts during the DAPS handover and continues after the DAPS handover. In some aspects, the UE may maintain both a source connection to the source gNB and a target connection to the target gNB for a portion of the DAPS handover.

[0105] The DAPS handover procedure may include several phases. These phases may include a handover preparation phase, a handover execution phase, and a handover completion phase. In some implementations, the UE may perform and report measurements during the handover preparation phase. During the handover execution phase, the UE may perform the handover by performing a RACH procedure with the target gNB and establishing an RRC connection with the target gNB. During the handover completion phase, the source gNB may forward stored communications associated with the UE to the target gNB and may release the UE from the source connection to the source gNB.

[0106] DAPS handover may involve multiple steps in each handover phase. After the UE determines that there is an event trigger, the UE may perform measurements (such as measurements of signals of the source cell or a neighboring cell) and transmit a measurement report to the source gNB of the source cell, as shown by reference numeral 630. The measurement report may indicate, for example, an RSRP parameter, an RSRQ parameter, an RSSI parameter, or a signal to interference plus noise ratio (SINR) parameter. The UE may start or continue to perform LBT based on the event trigger.

[0107] The source gNB may decide to handover the UE to the target gNB based on the measurement report. As indicated by reference numeral 632, the source gNB and the target gNB may prepare for the handover to the target gNB. The source gNB and the target gNB may communicate with each other to prepare for the DAPS handover. As part of the handover preparation, the source gNB may transmit a handover request to the target gNB to instruct the target gNB to prepare for the DAPS handover. The source gNB may transmit RRC context information associated with the UE or configuration information associated with the UE to the target gNB. The target gNB may prepare for the DAPS handover by reserving resources for the UE. After reserving the resources, the target gNB may transmit an acknowledgment (ACK) to the source gNB in ​​response to the handover request.

[0108] As indicated by reference numeral 634, the source gNB may provide an RRC reconfiguration message to the UE, thereby initiating a DAPS handover. The RRC reconfiguration message may include a handover command that instructs the UE to perform a DAPS handover from the source gNB to the target gNB. The handover command may include information associated with the target gNB, such as a RACH preamble assignment for accessing the target gNB. The UE's receipt of the RRC reconfiguration message including the handover command may trigger the start of the handover execution phase. At this point, the UE may begin performing LBT on a channel of the target cell. The source gNB and the target gNB may exchange user data for the UE. U2 carries control information between the UE and the source gNB. U3 carries control and bearer information between the source gNB and the target gNB. User data may be passed along with U2 and U3. In some aspects, once the UE has identified the target gNB for the target cell, the UE may begin performing LBT on a channel of the target cell.

[0109] The DAPS handover may involve transferring data over a user plane function (UPF) using an access and mobility management function (AMF) device that controls the UPF. The UPF and AMF devices may be located within the core network. The source gNB and the target gNB may communicate with the core network for mobility support and user plane functions. The source gNB may forward some data to the target gNB. As indicated by reference numeral 636, data reception and transmission with the source gNB may continue.

[0110] As indicated by reference numeral 638, as part of the handover execution phase, the UE may connect to the target gNB. The UE may connect to the target gNB by performing a RACH procedure with the target gNB. During this procedure, the UE may transmit uplink data, uplink control information, or an uplink reference signal (such as a sounding reference signal) to the source gNB, or may receive downlink data, downlink control information, or a downlink reference signal from the source gNB. While the UE is performing a RACH procedure with the target gNB, the UE may transmit uplink data, uplink control information, or an uplink reference signal (such as a sounding reference signal) to the source gNB, or may receive downlink data, downlink control information, or a downlink reference signal from the source gNB. Since the DAPS handover may be a make-before-break (MBB) handover, the UE may simultaneously maintain a source connection with the source gNB and a target connection with the target gNB.

[0111] After completing the RACH procedure on the target gNB (which may include synchronizing with the target gNB), the UE may stop performing LBT on the channels of the source cell. Alternatively, the UE may continue to perform LBT on the channels of the source cell.

[0112] Upon successfully establishing a target connection with the target gNB (such as via a RACH procedure), the UE may transmit an RRC reconfiguration complete message to the target gNB, as indicated by reference numeral 640. Receipt of the RRC reconfiguration message by the target gNB may trigger the start of a handover complete phase. As a result, the target gNB may decide that the UE will release the source connection. As indicated by reference numeral 642, the target gNB may provide a handover connection setup complete message to the source gNB. The message may cause the source gNB to stop transmitting data to the UE or stop receiving data from the UE. Additionally or alternatively, the message may cause the source gNB to forward communications associated with the UE to the target gNB, or notify the target gNB of the status of one or more communications with the UE. For example, the source gNB may send buffered downlink communications (such as downlink data) for the UE or uplink communications (such as uplink data) received from the UE to the target gNB. As indicated by reference numeral 644, the source gNB may notify the target gNB of a packet data convergence protocol (PDCP) state associated with the UE or a sequence number (SN) to be used for downlink communications with the UE.

[0113] As indicated by reference numeral 646, the target gNB may transmit an RRC reconfiguration message to the UE to instruct the UE to release the source connection to the source gNB. Upon receiving the instruction to release the source connection to the source gNB, the UE may cease communicating with the source gNB. For example, the UE may refrain from transmitting uplink communications to the source gNB, or may refrain from monitoring downlink communications from the source gNB. In some aspects, the UE may cease performing LBT on one or more channels of the source cell based on receiving the RRC reconfiguration message.

[0114] As indicated by reference numeral 648, the UE may transmit an RRC reconfiguration complete message to the target gNB to indicate that the connection between the source gNB and the UE is being released or has been released.

[0115] As indicated by reference numeral 650, the target gNB, UPF, or AMF device may communicate to switch the user plane path of the UE from the source gNB to the target gNB. Before switching the user plane path, downlink communications for the UE may be routed to the source gNB through the core network. After the user plane path is switched, downlink communications for the UE may be routed to the target gNB through the core network. As indicated by reference numeral 652, the source gNB and the target gNB may communicate to release the source gNB. In some aspects, the source gNB, the target gNB, or the UE may determine performance parameters or other performance parameters after the DAPS switch. At this time, the UE may be performing LBT on the channel of the target cell.

[0116] Figure 7 700 is a diagram illustrating an example in which a UE performs LBT during conditional handover. Figure 1 BS110a–110d depicted and described in Figure 2 BS 110 depicted and described in Figure 3 BS 310 depicted and described in Figure 1 UE 120a-120e depicted and described in Figure 2 UE 120 depicted and described in Figure 3 The UE may be handed over from the source cell to a cell provided by a candidate target gNB 1 (such as a UE 320 depicted and described in FIG. 1 ). Figure 3 The candidate target cellular cell is provided by BS110a-110d, BS110 or BS 330) or the candidate target gNB 2 (such as BS110 or BS 330) depicted and described in the figure.

[0117] As indicated by reference numeral 710, the UE may perform LBT on a channel of the source cell during a conditional handover. As indicated by reference numeral 720, the UE may perform LBT on a channel of a candidate target cell of candidate target gNB 1 or a candidate target cell of candidate target gNB 2 during a conditional handover. The UE may perform LBT on a channel of the source cell, the performance of which begins (or continues) at the start of the handover and ends during the conditional handover. The UE may perform LBT on a channel of the candidate target cell, the LBT starting during the conditional handover and continuing after the conditional handover. In some aspects, the UE may maintain both a source connection to the source cell and a target connection to the target cell for a portion of the conditional handover.

[0118] Conditional switching can involve combining Figure 6 The steps are similar to those described, except that there may be multiple candidate target cells, and the selection of a particular target cell among the candidate target cells may be based on the conditions of the particular target cell being satisfied.

[0119] After the UE determines that there is an event trigger, the UE may perform measurements (such as measurements on signals of the source cell or a neighboring cell) and transmit a measurement report to the source gNB of the source cell, as shown by reference numeral 730. The UE may start or continue to perform LBT based on the event trigger.

[0120] As indicated by reference numeral 732, the source gNB and each candidate target gNB of the candidate target cell may prepare for handover. As indicated by reference numeral 734, the source gNB may transmit an RRC reconfiguration message to the UE, thereby initiating a conditional handover. The RRC reconfiguration message may include a handover command instructing the UE to perform a conditional handover from the source gNB to one of the candidate target gNBs. The handover command may include information associated with each candidate target gNB, including conditions (such as thresholds) for switching to a particular candidate target gNB (such as target gNB 1). At this point, the UE may begin performing LBT on a channel of each of the candidate target cells. In some aspects, once the UE has identified a candidate target gNB for the target cell, the UE may begin performing LBT on a channel of the candidate target cell. The UE may simultaneously maintain a source connection to the source gNB and a target connection to the target gNB. As indicated by reference numeral 736, the UE may transmit an RRC reconfiguration complete message to the source gNB. As shown in conjunction with Figure 6As described, the source gNB and the target gNB may exchange user data for the UE. U2 carries control information between the UE and the source gNB. U3 carries control and bearer information between the source gNB and the target gNB. User data may be transferred along with U2 and U3.

[0121] As indicated by reference numeral 738, the UE may determine that an event for handover to the target cell of target gNB 1 is triggered. As indicated by reference numeral 740, the UE may release the source connection to the source cell and perform a conditional handover to the target gNB 1. At this point, the UE may stop performing LBT on the channels of the source cell. In some aspects, the UE may continue to perform LBT on the channels of the source cell.

[0122] As indicated by reference numeral 742, as part of the handover execution phase, the UE may connect to the target gNB 1. The UE may connect to the target gNB 1 by performing a RACH procedure with the target gNB 1.

[0123] After completing RACH procedures with target gNB 1 (which may include synchronizing with target gNB 1), the UE may stop performing LBT on the channels of the source cell. In some aspects, the UE may continue to perform LBT on the channels of the source cell.

[0124] Upon successfully establishing a connection with the target gNB 1 (such as via a RACH procedure), the UE may transmit an RRC reconfiguration complete message to the target gNB 1, as indicated by reference numeral 744. As indicated by reference numeral 746, the target gNB 1 may transmit a handover connection setup complete message to the source gNB. Receipt of the handover connection setup complete message by the target gNB 1 may trigger the source gNB to stop transmitting data to the UE or stop receiving data from the UE. Additionally or alternatively, the message may cause the source gNB to forward communications associated with the UE to the target gNB 1, or notify the target gNB 1 of the status of one or more communications with the UE. As indicated by reference numeral 748, the source gNB may notify the target gNB of the PDCP state associated with the UE or a sequence number used for downlink communications with the UE. In some aspects, the UE may stop performing LBT on a channel of the source cell.

[0125] As indicated by reference numeral 750, the source gNB may transmit a handover cancel message to any candidate target gNB that the UE did not select for handover. For example, the source gNB may transmit a handover cancel message to target gNB 2.

[0126] As indicated by reference numeral 752, the target gNB 1, UPF, or AMF device may communicate to switch the user plane path of the UE from the source gNB to the target gNB 1. Before the user plane path is switched, downlink communications for the UE may be routed to the source gNB through the core network. After the user plane path is switched, downlink communications for the UE may be routed to the target gNB 1 through the core network. As indicated by reference numeral 754, the source gNB may release the UE context for the UE. At this point, the UE may be performing LBT on a channel of the target gNB 1.

[0127] In combination Figure 6 and Figure 7 In any of the described scenarios, the UE may detect one or more LBT failures. The UE may detect an LBT failure when a channel of a cell is not clear. The UE may detect an LBT failure in an uplink or downlink direction. One or more LBT failures may include a continuous (multiple) LBT failure on the uplink, or a continuous LBT failure on the downlink. One or more LBT failures may include LBT failures on both the uplink and the downlink. For example, the UE may perform LBT in the uplink direction and detect an LBT failure in the uplink direction due to a busy channel. The UE may also detect an LBT failure in the downlink direction due to a loss of a reference signal. In this scenario, the source cell or the target cell may be performing LBT. In some aspects, if the UE detects an LBT failure for a channel of the source cell, the UE may switch from a bandwidth part (BWP) at the source cell to another BWP of the source cell. Additionally or alternatively, the UE may transmit a RACH message to the source cell. The UE may stop transmitting or receiving at the source cell. The UE may switch uplink data transmission to the target cell. The UE may report LBT failure to the target cell.

[0128] In some aspects, if the handover is a conditional handover and the UE detects a LBT failure on a channel of a candidate target cell, the UE may stop the conditional handover to the candidate target cell and attempt a conditional handover to another candidate target cell.

[0129] In a dual connectivity scenario, the SN of a cell may be used with the master node of the cell to increase the bandwidth or performance of the UE. Traffic on the master node and the SN may be aggregated. In this scenario, the UE may change the SN. In some aspects, the change may be performed using an operation comparable to a DAPS handover, a conditional handover, or another type of handover. That is, in combination with Figure 6 and Figure 7Some of the operations described may be applicable to SN change even though the operations are described for the master node.

[0130] For example, if the source secondary cell is unlicensed, the UE may perform LBT on the channel of the source secondary cell. The UE may decide to change from the source secondary cell to the target secondary cell. The UE may decide the change based on, for example, measurements from the source secondary cell or the target secondary cell. If the target secondary cell is unlicensed, the UE may start performing LBT on the channel of the target secondary cell.

[0131] The UE may stop performing LBT on the channel of the source secondary cell based on a stop condition. In some aspects, the stop condition may be completion of a RACH procedure at the target secondary cell. In some aspects, the stop condition may be receipt of a release source message from the target secondary cell.

[0132] In some aspects, if the UE detects an LBT failure for a channel of a source secondary cell, the UE may switch the BWP at the source secondary cell, stop transmission to the source secondary cell, or switch uplink transmission to the target secondary cell. Additionally or alternatively, the UE may transmit a RACH message to the source secondary cell. The UE may report the LBT failure to a primary cell associated with the source secondary cell.

[0133] Figure 8 800 is a diagram illustrating an example process 800 performed, for example, by a UE. Figure 1 and Figure 2 UE 120 depicted and described in Figure 3 An example of a UE 320) depicted and described in FIG. 3 performing LBT during handover.

[0134] like Figure 8 As shown in , in some aspects, process 800 may include determining that a handover of the UE from a source cell to a target cell is triggered (block 810). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may determine that a handover of the UE from the source cell to the target cell is triggered, as described above. In some aspects, the source cell is an unlicensed source cell.

[0135] like Figure 8As shown, in some aspects, process 800 may include performing LBT on the channels of the source cell during the handover based on the determination and until a stop condition occurs (block 820). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may perform LBT on the channels of the source cell during the handover based on the determination and until a stop condition occurs, as described above.

[0136] Process 800 may include additional aspects, such as any single aspect or any combination of aspects described below or in combination with one or more other processes described elsewhere herein.

[0137] In a first aspect, the stop condition includes one or more of the following operations: completion of a random access channel procedure at the target cell, or receipt of a release source message from the target cell.

[0138] In a second aspect, alone or in combination with the first aspect, the target cell is an unlicensed target cell, and performing LBT during handover includes performing LBT on a channel of the target cell based on receiving a handover command message.

[0139] In a third aspect, either alone or in combination with one or more of the first and second aspects, process 800 includes performing one or more of the following operations based on detecting one or more LBT failures on a channel of the target cell: stopping switching to the target cell, reporting one or more LBT failures, or continuing to connect to the source cell.

[0140] In a fourth aspect, either alone or in combination with one or more of the first to third aspects, process 800 includes performing one or more of the following operations based on detecting one or more LBT failures on a channel of a source cell: switching to another bandwidth portion at the source cell, or transmitting a random access channel message to a target cell.

[0141] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, process 800 includes ceasing transmission and reception at a source cell based on detecting one or more LBT failures on a channel of the source cell.

[0142] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, process 800 includes switching uplink data transmission to a target cell based on detecting one or more LBT failures on a channel of the source cell.

[0143] In a seventh aspect, either alone or in combination with one or more of the first to sixth aspects, process 800 includes reporting one or more LBT failures to a target cell based on detecting one or more LBT failures on a channel of a source cell.

[0144] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, the handover is a DAPS handover from a source cell to a target cell.

[0145] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, the handover is a conditional handover from the source cell to one of the target cell or another target cell.

[0146] In the tenth aspect, either alone or in combination with one or more of the first to ninth aspects, the target cell is an unlicensed candidate target cell, and performing LBT during switching includes performing LBT on a channel of the target cell and on a channel of another unlicensed candidate target cell based on receiving a switching command message.

[0147] In an eleventh aspect, either alone or in combination with one or more of the first to tenth aspects, process 800 includes stopping conditional switching to a target cell and attempting conditional switching to another target cell based on detecting one or more LBT failures on a channel of the target cell.

[0148] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, process 800 includes transitioning to another bandwidth portion at a target cell based on detecting one or more LBT failures on a channel of the target cell.

[0149] In a thirteenth aspect, either alone or in combination with one or more of the first to twelfth aspects, process 800 includes reporting one or more LBT failures to a source cell or to another target cell based on detecting one or more LBT failures on a channel of the target cell.

[0150] In a fourteenth aspect, alone or in combination with one or more of the first to thirteenth aspects, the channel is an uplink channel.

[0151] In a fifteenth aspect, either alone or in combination with one or more of the first to fourteenth aspects, the channel is a downlink channel.

[0152] although Figure 8 An example block diagram of process 800 is shown, but in some aspects, process 800 may include Figure 8Additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the process 800. Additionally or alternatively, two or more blocks of process 800 may be executed in parallel.

[0153] Fig. 9 900 is a diagram illustrating an example process 900 performed, for example, by a UE. Figure 1 and Figure 2 UE 120 depicted and described in Figure 3 An example of a UE 320) depicted and described in FIG. 3 performing LBT during handover.

[0154] like Fig. 9 As shown, in some aspects, process 900 may include determining that a handover of the UE from the source cell to the target cell is triggered (block 910). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may determine that a handover of the UE from the source cell to the target cell is triggered, as described above. In some aspects, the target cell is an unlicensed target cell.

[0155] like Fig. 9 As shown, in some aspects, process 900 may include performing LBT on a channel of a target cell based on receiving a handover command message during handover (block 920). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may perform LBT on a channel of a target cell based on receiving a handover command message during handover, as described above.

[0156] Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below or in combination with one or more other processes described elsewhere herein.

[0157] In a first aspect, process 900 includes, based on detecting one or more LBT failures on a channel of a target cell, at least one of: stopping handover to the target cell, reporting one or more LBT failures, or continuing to connect to the source cell.

[0158] In a second aspect, alone or in combination with the first aspect, the handover is a DAPS handover from a source cell to a target cell.

[0159] In a third aspect, alone or in combination with one or more of the first to second aspects, the handover is a conditional handover from the source cell to one of the target cell or another target cell.

[0160] In a fourth aspect, alone or in combination with one or more of the first to third aspects, performing LBT during handover includes performing LBT on a channel of the target cell and on a channel of another unlicensed candidate target cell based on receiving a handover command message.

[0161] although Fig. 9 An example block diagram of process 900 is shown, but in some aspects, process 900 may include Fig. 9 Additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the process 900. Additionally or alternatively, two or more blocks of the process 900 may be executed in parallel.

[0162] Fig.10 1 is a diagram illustrating an example process 1000 performed, for example, by a UE. Figure 1 and Figure 2 UE 120 depicted and described in Figure 3 An example of a UE 320) depicted and described in FIG. 3 detecting a failure of LBT during handover.

[0163] like Fig.10 As shown, in some aspects, process 1000 may include determining that a handover of the UE from a source cell to a target cell is triggered (block 1010). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may determine that a handover of the UE from a source cell to a target cell is triggered, as described above.

[0164] like Fig.10 As shown, in some aspects, process 1000 may include detecting one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during handover (block 1020). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may detect one or more LBT failures on a downlink channel from one or more of the source cell or the target cell during handover, as described above.

[0165] Process 1000 may include additional aspects, such as any single aspect or any combination of aspects described below or in combination with one or more other processes described elsewhere herein.

[0166] In a first aspect, detecting one or more LBT failures includes detecting that one or more reference signals are not received from one or more of a target cell or a source cell.

[0167] In a second aspect, either alone or in combination with the first aspect, process 1000 may include, based on detecting one or more LBT failures on a channel of a source cell, performing one or more of the following operations: switching to another bandwidth portion at the source cell, transmitting a random access channel message to a target cell, ceasing transmission and reception at the source cell, or switching uplink data transmission to the target cell.

[0168] In a third aspect, either alone or in combination with one or more of the first and second aspects, process 1000 includes performing one or more of the following operations based on detecting one or more LBT failures on a channel of the target cell: stopping switching to the target cell, reporting one or more LBT failures, or continuing to connect to the source cell.

[0169] although Fig.10 An example block diagram of process 1000 is shown, but in some aspects, process 1000 may include Fig.10 Additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the process 1000. Additionally or alternatively, two or more blocks of the process 1000 may be executed in parallel.

[0170] Fig.11 1 is a diagram illustrating an example process 1100 performed, for example, by a UE. Process 1100 is a UE (e.g., Figure 1 and Figure 2 UE 120 depicted and described in Figure 3 An example of a UE 320) depicted and described in FIG. 3 performing LBT during an SN change.

[0171] like Fig.11 As shown, in some aspects, process 1100 may include determining that a SN change of the UE is triggered (block 1110). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may determine that a SN change of the UE is triggered, as described above.

[0172] like Fig.11 As shown, in some aspects, process 1100 may include: performing LBT on one or more of the channels of the unlicensed source secondary cell or the channels of the unlicensed target secondary cell during the SN change (block 1120). For example, the UE (such as using controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, or antenna 252) may perform LBT on one or more of the channels of the unlicensed source secondary cell or the channels of the unlicensed target secondary cell during the SN change, as described above.

[0173] Process 1100 may include additional aspects, such as any single aspect or any combination of aspects described below or in combination with one or more other processes described elsewhere herein.

[0174] In a first aspect, performing LBT during the SN change includes performing LBT on a channel of the unlicensed source secondary cell based on the determination and until a stop condition occurs.

[0175] In a second aspect, alone or in combination with the first aspect, the stop condition comprises one or more of the following operations: completion of a random access channel procedure at the unlicensed target secondary cell, or receipt of a release source message from the unlicensed target secondary cell.

[0176] In a third aspect, either alone or in combination with one or more of the first to second aspects, process 1100 includes performing one or more of the following operations based on detecting one or more LBT failures on a channel of an unlicensed source secondary cell: switching to another bandwidth portion at the unlicensed source secondary cell, transmitting a random access channel message to an unlicensed target secondary cell, or reporting one or more LBT failures to an associated primary cell.

[0177] In a fourth aspect, alone or in combination with one or more of the first to third aspects, performing LBT during the SN change includes: performing LBT on a channel of an unlicensed target secondary cell based on receiving an SN change message.

[0178] although Fig.11 An example block diagram of process 1100 is shown, but in some aspects, process 1100 may include Fig.11 Additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the process 1100. Additionally or alternatively, two or more blocks of the process 1100 may be executed in parallel.

[0179] Fig.12 1 is a diagram illustrating an example process 1200 performed, for example, by a base station. Process 1200 is a base station (e.g., Figure 1 and Figure 2 The base station 110 depicted and described in Figure 3 An example of BS 310 or BS 330) receiving an LBT failure report during handover is depicted and described in FIG.

[0180] like Fig.12As shown, in some aspects, process 1200 may include triggering a handover of the UE (block 1210). For example, a base station (such as using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may trigger a handover of the UE, as described above.

[0181] like Fig.12 As shown, in some aspects, process 1200 may include receiving one or more LBT failure reports from the UE during handover (block 1220). For example, the base station (such as using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may receive one or more LBT failure reports from the UE during handover, as described above.

[0182] like Fig.12 As shown, in some aspects, process 1200 may include: performing an action for the UE based on one or more LBT failure reports (block 1230). For example, a base station (such as using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may perform an action for the UE based on one or more LBT failure reports, as described above.

[0183] Process 1200 may include additional aspects, such as any single aspect or any combination of aspects described below or in combination with one or more other processes described elsewhere herein.

[0184] In a first additional aspect, performing the action includes dropping a source cell or a target cell for the UE.

[0185] although Fig.12 An example block diagram of process 1200 is shown, but in some aspects, process 1200 may include Fig.12 Additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the process 1200. Additionally or alternatively, two or more blocks of the process 1200 may be executed in parallel.

[0186] Fig.13 1 is a diagram illustrating an example process 1300 performed, for example, by a base station. Process 1300 is a base station (e.g., Figure 1 and Figure 2 The base station 110 depicted and described in Figure 3 An example of BS 310 or BS 330) receiving an LBT failure report during an SN change is depicted and described in FIG.

[0187] like Fig.13As shown, in some aspects, process 1300 may include triggering a change in the SN of the secondary cell group (block 1310). For example, the base station (such as using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may trigger a change in the SN of the secondary cell group, as described above.

[0188] like Fig.13 As shown, in some aspects, process 1300 may include: receiving one or more LBT failure reports from the UE during the change (block 1320). For example, the base station (such as using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may receive one or more LBT failure reports from the UE during the change, as described above.

[0189] like Fig.13 As shown, in some aspects, process 1300 may include: performing an action for the UE based on one or more LBT failure reports (block 1330). For example, a base station (such as using controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, or antenna 234) may perform an action for the UE based on one or more LBT failure reports, as described above.

[0190] Process 1300 may include additional aspects, such as any single aspect or any combination of aspects described below or in combination with one or more other processes described elsewhere herein.

[0191] In a first additional aspect, performing the action includes dropping a secondary cell for the UE.

[0192] although Fig.13 Example blocks of process 1300 are shown, but in some aspects, process 1300 may include Fig.13 Additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in the process 1300. Additionally or alternatively, two or more blocks of the process 1300 may be executed in parallel.

[0193] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired by practice of the various aspects.

[0194] As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented with hardware, firmware, or a combination of hardware and software. As used herein, the phrase "based on" is intended to be broadly interpreted as "based at least in part on."

[0195] Some aspects are described herein in conjunction with a threshold value. As used herein, satisfying a threshold value may refer to a value that is greater than a threshold value, greater than or equal to a threshold value, less than a threshold value, less than or equal to a threshold value, equal to a threshold value, or not equal to a threshold value.

[0196] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc.

[0197] The various illustrative logics, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the implementations disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. This interchangeability of hardware and software has been generally described in terms of their functionality and illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0198] The hardware and data processing devices for implementing the various illustrative logics, logic blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented or executed with a general purpose single-chip or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (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. A general purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration. In some aspects, specific processes and methods may be performed by a circuit system dedicated to a given function.

[0199] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware (including the structures disclosed in this specification and their structural equivalents), or in any combination thereof. Implementations of the subject matter described in this specification may also be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a computer storage medium for execution by a data processing apparatus or for controlling the operation of a data processing apparatus.

[0200] If implemented in software, each function can be stored on a computer-readable medium or transmitted therethrough as one or more instructions or codes. The process of the method or algorithm disclosed herein can be implemented in a processor executable software module that can reside on a computer-readable medium. Computer-readable media include both computer storage media and communication media, including any medium that can be implemented to transfer a computer program from one place to another. Storage media can be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, or any other medium that can be used to store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection may also be appropriately referred to as a computer-readable medium. As used herein, disks and discs include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks and blue-ray discs, wherein disks often reproduce data magnetically and discs reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine-readable medium and a computer-readable medium, which may be incorporated into a computer program product.

[0201] Various modifications to the aspects described in this disclosure may be apparent to those skilled in the art, and the universal principles defined herein may be applied to other aspects without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the aspects shown herein, but should be granted the broadest scope consistent with the disclosure, the principles and novel features disclosed herein.

[0202] In addition, one of ordinary skill in the art will readily appreciate that the terms "upper" and "lower" are sometimes used for convenience in describing the drawings and indicate relative positions corresponding to the orientation of the drawings on a correctly oriented page, and may not reflect the actual orientation of any device as implemented.

[0203] Certain features described in the context of separate aspects in this specification may also be implemented in a single aspect in combination. On the contrary, various features described in the context of a single aspect may also be implemented in multiple aspects separately or in any suitable sub-combination. In addition, although the features may be described above as acting in a certain combination and even initially claimed, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may be for a sub-combination or a variant of a sub-combination. Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring such operations to be performed in the particular order shown or in a sequential order, or to perform all the operations explained in order to achieve the desired result. In addition, the accompanying drawings may schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted may be incorporated into the schematically illustrated example process. For example, one or more additional operations may be performed before, after, simultaneously or between any of the illustrated operations. In some environments, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the aspects described above should not be understood as requiring such separation in all aspects, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other aspects also fall within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in different orders and still achieve the desired results.

Claims

1. A wireless communication method performed by a device of a user equipment (UE), comprising: Performing listen before talk (LBT) on a channel of an unlicensed secondary cell during a secondary node (SN) change; as well as One or more LBT failures are reported to a primary cell associated with the unlicensed secondary cell.

2. The method of claim 1, further comprising: Switching to another bandwidth portion at the unlicensed secondary cell is performed based at least in part on the one or more LBT failures.

3. The method of claim 1 , wherein performing the LBT comprises: The LBT is executed until a stop condition occurs.

4. The method of claim 3, wherein the stop condition comprises one or more of completion of a random access channel procedure or receipt of a release source message.

5. The method of claim 1, further comprising: Uplink transmissions are switched to the unlicensed secondary cell based at least in part on the one or more LBT failures.

6. The method of claim 1, further comprising: A random access channel message is transmitted to the unlicensed secondary cell based at least in part on the one or more LBT failures.

7. The method of claim 1, wherein performing the LBT comprises: The LBT is performed based at least in part on receiving an SN change message.

8. The method of claim 1, wherein the SN change is triggered based at least in part on measurements from a source secondary cell or a target secondary cell.

9. An apparatus for a user equipment (UE) for wireless communication, comprising: a processing system configured to perform listen-before-talk (LBT) on a channel of an unlicensed secondary cell during a secondary node (SN) change; as well as An interface is configured to output a report indicating one or more LBT failures to a primary cell associated with the unlicensed secondary cell.

10. The apparatus of claim 9, wherein the processing system is further configured to: Switching to another bandwidth portion at the unlicensed secondary cell is performed based at least in part on the one or more LBT failures.

11. The apparatus of claim 9, wherein the processing system is further configured to: The LBT is executed until a stop condition occurs.

12. The apparatus of claim 11, wherein the stop condition comprises one or more of completing a random access channel procedure or receiving a release source message.

13. The apparatus of claim 9, wherein the processing system is further configured to: Uplink transmissions are switched to the unlicensed secondary cell based at least in part on the one or more LBT failures.

14. The apparatus of claim 9, wherein the interface is further configured to: A random access channel message is output to the unlicensed secondary cell based at least in part on the one or more LBT failures.

15. The apparatus of claim 9, wherein to perform the LBT, the processing system is configured to: The LBT is performed based at least in part on receiving an SN change message.

16. The apparatus of claim 9, wherein the SN change is triggered based at least in part on measurements from a source secondary cell or a target secondary cell.

17. A wireless communication method performed by a device of a user equipment (UE), comprising: communicating with a source cell; receiving a message including information associated with a handover of the UE from the source cell to a target cell; performing listen before talk (LBT) on a channel of the target cell based on the message and while the UE is communicating with the source cell; as well as LBT is performed on the channel of the source cell after receiving the message and until a stop condition occurs.

18. The method of claim 17, further comprising: releasing the connection with the source cell; as well as The switching is performed. The method of claim 17 , wherein the switching is a conditional switching.

20. The method of claim 17, further comprising: The communication with the source cell is ceased based on a failure of LBT on the channel of the source cell.

21. The method of claim 17, further comprising: Switching to another bandwidth portion of the source cell based on a failure of LBT on the channel of the source cell.

22. The method of claim 17, further comprising: A random access channel message is transmitted based on a LBT failure on the channel of the source cell.

23. The method of claim 17, wherein the stop condition is a conditional switch execution condition.

24. An apparatus of a user equipment (UE) for wireless communication, comprising: interface, the interface being configured to: communicating with a source cell; as well as receiving a message including information associated with a handover of the UE from the source cell to a target cell; as well as A processing system, the processing system being configured to: performing listen before talk (LBT) on a channel of the target cell based on the message and while the UE is communicating with the source cell; as well as LBT is performed on the channel of the source cell after receiving the message and until a stop condition occurs.

25. The apparatus of claim 24, wherein the processing system is further configured to: releasing the connection with the source cell; and The switching is performed.

26. The apparatus of claim 24, wherein the switching is a conditional switching.

27. The apparatus of claim 24, wherein the interface is further configured to: The communication with the source cell is ceased based on a failure of LBT on the channel of the source cell.

28. The apparatus of claim 24, switching to another bandwidth portion of the source cell based on a failure of LBT on the channel of the source cell.

29. The apparatus of claim 24, wherein the interface is further configured to: A random access channel message is output based on a LBT failure on the channel of the source cell.

30. The apparatus of claim 24, wherein the stop condition is a conditional switch execution condition.

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