CN114615692B - Wireless communication apparatus and method - Google Patents

Abstract

An apparatus and method of wireless communication are provided. A method of a User Equipment (UE) includes configuring a Listen Before Talk (LBT) failure recovery procedure by a base station, detecting an LBT failure for each Uplink (UL) bandwidth part (BWP), and triggering UL LBT failure Medium Access Control (MAC) Control Elements (CEs) of one or more serving cells for triggering the LBT failure. This may solve the problems of the prior art, provide good communication performance for any serving cell triggering LBT failure triggering MAC CE of UL LBT failure, and/or provide high reliability.

Description

Wireless communication apparatus and method

This application is a divisional application filed with the China Patent Office on November 18, 2020, with the application number 202080047286.2 and the invention title is "Device and Method for Wireless Communication", the entire content of which is incorporated into this application by reference.

Technical field

The present application relates to the field of communication systems, and more specifically, to a wireless communication device and method that can provide good communication performance and/or high reliability.

Background technique

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, etc. These wireless communication systems can support communications with multiple users by sharing available system resources (eg, time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems, such as long term evolution (LTE) systems and fifth generation (5G) systems, which can be called new radio (NR) systems . A wireless multiple access communication system may include some base stations or network access nodes, each base station or node supporting communications of multiple communication devices simultaneously, and these devices may be called user equipment (UE).

A wireless communication network may include base stations that may support UE communications. The UE may communicate with the base station via downlink and uplink. The downlink refers to the communication link from the base station to the UE, and the uplink refers to the communication link from the UE to the base station. In wireless communication systems operating in high frequency bands, paging transmission/reception will lead to an increase in signaling overhead and UE power consumption.

Therefore, there is a need for a wireless communication device (such as user equipment (UE) and/or base station) and method, which can solve the problems in the prior art and provide a wireless communication device for anyone who has triggered a listen before talk (LBT) ) failure event, the serving cell triggers the medium access control (MAC) control element (CE) of the UL LBT failure, providing good communication performance, and/or providing high reliability.

Contents of the invention

One purpose of the present disclosure is to propose a wireless communication device (such as user equipment (UE) and/or base station) and method, which can solve the problems in the prior art. For any serving cell that has triggered an LBT failure event, ULLBT fails MAC CE, provides good communication performance, and/or provides high reliability.

In a first aspect of the present disclosure, a method for wireless communication by a user equipment (UE) includes configuring a listen-before-talk (LBT) failure recovery procedure through a base station; detecting each uplink (UL) bandwidth portion (bandwidth part, BWP); and triggering a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells used to trigger LBT failure.

In a second aspect of the present disclosure, a method of wireless communication of a base station includes configuring a listen-before-talk (LBT) failure recovery procedure to a user equipment (UE); controlling the UE to detect each uplink (UL) bandwidth Partial (BWP) LBT failure; and controlling the UE to trigger a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that trigger LBT failure.

In a third aspect of the disclosure, a user equipment includes a memory, a transceiver, and a processor coupled to the memory and transceiver. The processor is configured by the base station with a Listen Before Talk (LBT) failure recovery procedure. The processor is configured to detect LBT failure per uplink (UL) bandwidth part (BWP). The processor is configured to trigger a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells for triggering LBT failure.

In a fourth aspect of the disclosure, a base station includes a memory, a transceiver, and a processor coupled to the memory and transceiver. The processor is configured to configure a listen before talk (LBT) failure recovery procedure to a user equipment (UE). The processor is configured to control the UE to detect LBT failure per uplink (UL) bandwidth part (BWP). The processor is configured to control the UE to trigger a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggers LBT failure.

In a fifth aspect of the present disclosure, instructions are stored on a non-volatile machine-readable storage medium, and when executed by a computer, the instructions cause the computer to perform the above method.

In a sixth aspect of the present disclosure, a chip includes a processor configured to call and run a computer program stored in a memory, so that a device installing the chip performs the above method.

In a seventh aspect of the present disclosure, a computer-readable storage medium stores a computer program to cause a computer to execute the above method.

In an eighth aspect of the present disclosure, a computer program product includes a computer program, and the computer program causes a computer to perform the above method.

In a ninth aspect of the present disclosure, a computer program causes a computer to perform the above method.

Description of the drawings

In order to explain the embodiments of the present disclosure or related technologies more clearly, the drawings in the embodiments will be briefly introduced below. Obviously, these drawings are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without any prerequisites.

1 is a block diagram of one or more user equipments (UEs) and a wireless communication base station in a communication network system according to one embodiment of the present disclosure.

FIG. 2 is a flowchart of a method of wireless communication performed by a user equipment (UE) according to one embodiment of the present disclosure.

3 is a flowchart of a method of wireless communication performed by a base station according to one embodiment of the present disclosure.

4 is a schematic diagram of a MAC CE with LBT failure for one octet according to an embodiment of the present disclosure.

5 is a schematic diagram of a MAC CE with LBT failure of four octets according to one embodiment of the present disclosure.

Figure 6 is a block diagram of a system for wireless communications according to one embodiment of the present disclosure.

Detailed ways

The technical matters, structural features, achieved goals and effects of the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Specifically, the terms used in the embodiments of the present disclosure are only for the purpose of describing a certain embodiment, and are not intended to limit the disclosure.

Unlicensed spectrum is a shared spectrum. Communication equipment of different communication systems can use unlicensed spectrum, as long as the unlicensed compliance with national or regional regulatory requirements for a certain spectrum. There is no need to apply to the government for exclusive spectrum authorization.

In order to allow various communication systems that use unlicensed spectrum for wireless communications to coexist friendly in the spectrum, some countries or regions have stipulated regulatory requirements that must be met when using unlicensed spectrum. For example, communication devices follow a listen-before-talk (LBT) procedure, that is, the communication device needs to perform channel sensing before transmitting a signal on the channel. When the result of LBT indicates that the channel is idle, the communication device can perform signal transmission; otherwise, the communication device cannot perform signal transmission. In order to ensure fairness, once a communication device successfully occupies the channel, the transmission time cannot exceed the maximum channel occupancy time (MCOT).

On an unlicensed carrier, for the channel occupancy time obtained by a base station, it can share the channel occupancy time with user equipment (UE) for transmitting uplink signals or uplink channels. In other words, when the base station shares its own channel occupancy time with the UE, the UE can obtain the channel using an LBT mode with a higher priority than that used by the UE itself, thereby The channel is obtained with greater probability. LBT is also called channel access procedure. The UE performs the channel access procedure before the transmission. If the channel access procedure is successful, that is, the channel is perceived to be idle, the UE starts to perform the transmission. If the channel access procedure is unsuccessful, that is, the channel is perceived as non-idle, the UE cannot perform the transmission.

In the current discussion, it was agreed to introduce a mechanism to handle uplink (UL) LBT failures: A mechanism is adopted in the medium access control (MAC) specification to handle so-called UL LBT failures, in which "continuous "UL LBT failed" is used for problem detection, at least for UL transmission of scheduling request (SR), random access channel (RACH) and physical uplink shared channel (PUSCH) problem detection.

In the current discussion, further agreement has been reached regarding the UL LBT failure: the layer 2 (L2) LBT failure mechanism can take into account any LBT failure regardless of the UL transmission type. The UL LBT failure mechanism can have the same recovery mechanism for all failures regardless of UL transmission type. Further enhancements to the basic mechanism are not excluded: a "threshold" for the maximum number of LBT failures that triggers a "sustained" LBT failure event will be used. A timer and a counter are introduced, the counter is reset when the timer expires, and the counter is incremented when a UL LBT failure occurs. The timer is started/restarted when the UL LBT failure occurs. Summary of the basic mechanism: The mechanism inspired by Beam failure detection (BFD) seems to be supported by many people, but there are still some issues. It was agreed that this would be a basic mechanism for further review at a later date to see if further improvements were needed. ULLBT failures are detected per bandwidth part (BWP). User equipment (UE) will report persistent UL LBT failures occurring on a primary secondary cell (PSCell) and secondary cell (SCell). It is assumed that the SCell failure report for beamforming (BF) is reused.

Additionally, in the current discussion, there are the following agreed conventions. The MAC relies on receiving UL LBT failure notifications from the physical layer to detect persistent UL LBT failures. If there is another BWP with configured RACH resources, when the persistent LBT on the primary cell (primary cell, PCell) or PSCell fails, a UE switches to another BWP and starts RACH. If the persistent UL LBT failure is detected on the PCell and the UL LBT failure is detected on "N" possible BWPs, the UE performs radio link failure (radio link failure, RLF) recovery. When persistent uplink LBT failure is detected on the PSCell, the UE passes the secondary cell group (SCG) after detecting persistent UL LBT failure on "N" BWPs. The failure information program notifies the master node (MN). "N" is the number of configured BWPs with configured physical random access channel (PRACH) resources. If N is greater than 1, it is up to the UE to decide which BWP to select. When a persistent uplink LBT failure is detected on an SCell, a new MAC control element (control element, CE) is used to report the persistent uplink LBT failure to the node to which the SCell belongs. Further study issues (FFS) include: whether the MAC CE can be used to report the persistent uplink LBT failure on the PCell.

Some current technologies are related to UL LBT failure areas. More specifically, some of the current technologies are as follows.

UL LBT for SCell or multiple SCells failed:

There are some issues for further study (FFS) regarding persistent UL LBT failure detection on SCell. FFS: What is the priority of MAC CE in logical channel prioritization (LCP). FFS: Do we need to handle the situation where no subsequent UL resources are available. FFS: Do we need to limit the transmission of MAC CE to BWPs other than the BWP that declares LBT failure?

For the first FFS, in some views of some embodiments of the present disclosure, the SCell may have some problems if the UE detects persistent ULLBT failures, which is similar to the situation when the UE declares the SCell's beam failure, Therefore, some opinions believe that the MAC CE used to report SCell LBT issues can have a similar priority to the beam failure recovery (beam failure recovery, BFR) MAC CE being discussed.

Proposal 1: In some embodiments of the present disclosure, MAC CE for UL LBT issues may have a similar priority as BFR MAC CE.

Regarding the second FFS, some opinions believe that similar to the situation of the BFR MAC CE, when there are no available UL resources for use, the UE needs to send a scheduling request SR to the network to request uplink resources. Otherwise, the network will not be able to know ULLBT problem.

Proposal 2: In some embodiments of the present disclosure, similar to the BFR MAC CE, if there are no available UL resources, the UE can trigger a scheduling request scheduling request SR for sending MAC CE regarding the SCell UL LBT issue.

Regarding the third FFS, there need not be such a restriction that the MAC CE should be transmitted on a different serving cell than the SCell with the UL LBT issue. The reason is that the persistent LBT failure only reflects the channel occupancy situation in a period and does not mean that the channel is always occupied.

Proposal 3: In some embodiments of the present disclosure, the MAC CE does not need to be restricted and should be transmitted on different serving cells other than the SCell where the ULLBT problem exists.

The MAC CE should be used to indicate which SCell has the persistent UL LBT failure. If a MAC CE has been triggered but not sent to the network, there is no need to trigger the MAC CE again.

Proposal 4: In some embodiments of the present disclosure, if there is already a MAC CE triggered to indicate persistent UL LBT failure for the SCell, there is no need to retrigger the MAC CE.

Regarding the MAC CE format, there are some opinions that the persistent ULLBT failure is triggered independently between different SCells. It is possible that multiple MAC CEs are triggered for multiple different SCells if these SCells have the persistent UL LBT failure. From this perspective, it is beneficial to incorporate all the related multiple SCells with the persistent UL LBT failure into one MAC CE format, that is, the MAC CE format should support multiple entries to represent all the related SCells with the persistent UL LBT failure. Described persistent UL LBT failure for multiple SCells.

Proposal 5: In some embodiments of the present disclosure, the MAC CE format should support multiple entries to indicate all SCells that have declared the persistent UL LBT failure.

SpCell's UL LBT failed:

In the current discussion, it is agreed as follows: If the PSCell detects a persistent LBT failure, the UE can report the LBT failure to the master node (MN) through the SCG failure information procedure.

When persistent uplink LBT failure is detected on the PSCell, the UE notifies the master node through the SCG failure information procedure after detecting persistent UL LBT failure on "N" BWPs. MN.

After detecting persistent UL LBT failures on "N" BWPs, the SCG failure information is relied upon to report said LBT failures for PSCell. The network should be informed that the LBT on the PSCell failed. Currently, there are different conditions that can trigger the SCG invalidation procedure. In order for the network to distinguish the LBT failure from other situations, it is proposed to add a new failure type when reporting SCG failure information SCGFailureInformation.

Proposal 6: In some embodiments of the present disclosure, a new failure type of PSCell sustained UL LBT failure is added to the SCG failure information SCGFailureInformation.

If Proposal 6 is confirmed, there is no need to trigger MAC CE for the PSCell if there are persistent UL LBT failures.

There is one FFS left in the current discussion, that is, whether MAC CE should be applied to PCell.

In some opinions, it is considered unnecessary, that is, MAC CE should not be applied to PCell. The reason is that the network can learn about the LBT failure problem on PCell based on BWP switching, that is, BWP switching to another non-initial BWP. Even though the PCell may only have a single initial BWP, some companies may believe that in this case the gNB may not distinguish the said LBT failure issue from other causes. However, some opinions believe that the UE only needs to start the RLF procedure in the case of PCell LBT problems, and there is no other special treatment for this situation. So there should be no problem even if in some cases the gNB may not differentiate said situation from others.

Proposal 7: In some embodiments of the present disclosure, the UE does not trigger MAC CE when declaring persistent UL LBT failure on SpCell.

Regarding how to report persistent UL LBT failures as described, it is agreed as follows: Use MAC CE for SCell. However, for SpCell (including PCell and PSCell), there is no conclusion yet. A possible problem is that the network may not know how to trigger RACH if the UE fails to trigger ULLBT and switches UL BWP for SpCell.

Therefore, some embodiments of the present disclosure propose a device (such as user equipment (UE) and/or base station) and a wireless communication method that can solve the problems in the prior art. For any serving cell that triggers LBT failure, ULLBT fails MAC CE, provides good communication performance, and/or provides high reliability.

FIG. 1 illustrates that, in some embodiments, one or more user equipments (UEs) 10 and base stations (eg, gNBs or eNBs) for wireless communications in a communications network system 30 according to one embodiment of the present disclosure are provided. 20. The communication network system 30 includes the one or more UEs 10 and the base station 20 . The one or more UEs 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12 and the transceiver 13. The base station 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22 and the transceiver 23. The processor 11 or 21 may be configured to implement the proposed functions, procedures and/or methods described in this specification. The various layers of the radio interface protocol may be implemented in the processor 11 or 21. The memory 12 or 22 is operatively coupled with the processor 11 or 21 and stores various information to operate the processor 11 or 21. The transceiver 13 or 23 is operatively coupled with the processor 11 or 21, and the transceiver 13 or 23 transmits and/or receives radio signals.

The processor 11 or 21 may include an application-specific integrated circuit (ASIC), other chipset, logic circuit and/or data processing device. The memory 12 or 22 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and/or other storage devices. The transceiver 13 or 23 may include baseband circuitry for processing radio frequency signals. When the present embodiment is implemented in software, the techniques described herein may be implemented using modules (eg, programs, functions, etc.) that perform the functions described herein. These modules may be stored in the memory 12 or 22 and executed by the processor 11 or 21. The memory 12 or 22 may be implemented within the processor 11 or 21 or external to the processor 11 or 21, in which case it may be coupled to the processor 11 or 21 in various ways known in the art. The processor 11 or 21 is communicatively coupled.

In some embodiments, the processor 11 is configured by the base station 20 to have a Listen Before Talk (LBT) failure recovery procedure. The processor 11 is configured to detect LBT failure for each uplink (UL) bandwidth part (BWP). The processor 11 is configured for triggering a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells for triggering LBT failure. This can solve the problems in the existing technology, trigger the MAC CE of UL LBT failure for any serving cell that triggers LBT failure, provide good communication performance, and/or provide high reliability.

In some embodiments, the processor 21 is configured to configure a listen before talk (LBT) failure recovery procedure to the user equipment (UE) 10 . The processor 21 is configured to control the UE 10 to detect LBT failure per uplink (UL) bandwidth part (BWP). The processor 21 is configured to control the UE 10 to trigger a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggers LBT failure. This can solve the problems in the existing technology, trigger the MAC CE of UL LBT failure for any serving cell that triggers LBT failure, provide good communication performance, and/or provide high reliability.

Figure 2 illustrates a method 200 of wireless communication of user equipment (UE) according to one embodiment of the present disclosure. In some embodiments, the method 200 includes block 202, a listen-before-talk (LBT) failure recovery procedure configured by the base station, block 204, for detecting each uplink (UL) bandwidth part (BWP) of LBT failure, and block 206 for triggering a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggers LBT failure. This can solve the problems in the existing technology, trigger the MAC CE of UL LBT failure for any serving cell that triggers LBT failure, provide good communication performance, and/or provide high reliability.

Figure 3 illustrates a method 300 of wireless communication of a base station according to one embodiment of the present disclosure. In some implementations, the method 300 includes: block 302 for configuring a listen-before-talk (LBT) failure recovery procedure to the user equipment (UE), block 304 for controlling the UE to detect each uplink LBT failure of the link (UL) bandwidth part (BWP), and block 306 for triggering a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggered the LBT failure. This can solve the problems in the existing technology, trigger the MAC CE of ULLBT failure for any serving cell that triggers LBT failure, provide good communication performance, and/or provide high reliability.

In some embodiments, the method further includes transmitting, by the UE to the base station, a MAC CE having serving cell information configured as a MAC CE for triggering the UL LBT failure. In some embodiments, the UE cancels one or more triggered MAC CEs if the MAC CEs have been transmitted on the one or more serving cells. In some embodiments, the serving cell information of the MAC CE includes at least one of the following: a report of a failed cell; a MAC CE format configured to support entries indicating one or more cells, where The one or more cells announce the LBT failure; one or more cell indexes of the MAC CE where the LBT failure occurs; or BWP related information in the MAC CE. In some embodiments, the LBT failure includes persistent LBT failure. In some embodiments, if the UE declares persistent LBT failure for an activated UL BWP, and if the one or more serving cells include one or more secondary cells (SCells), the UE indicates multiplexing and The assembly entity includes the MAC CE of the UL LBT failure in subsequent uplink transmissions. In some embodiments, the uplink transmission does not occur on one or more SCells that have declared the persistent LBT failure.

In some embodiments, if there are no UL resources available on one or more SCells that have not declared the persistent LBT failure and/or no UL resources available on one or more special cells (SpCells), the A user equipment (UE) triggers a scheduling request (SR) to request UL grant (UL grant). In some embodiments, if the UE declares persistent LBT failure for an activated UL BWP, and if one or more serving cells include one or more special cells (SpCells), the UE performs at least one of the following: If the persistent LBT failure is announced in one or more UL BWPs configured with one or more physical random access channels (PRACH) in the one or more special cells, the user equipment reports to a or multiple upper layers indicating the persistent LBT failure; instructing the multiplexing and assembly entity to include the MAC CE of the UL LBT failure in the subsequent uplink transmission; if the persistent LBT failure has not been declared yet There are no available UL resources on another or other serving cells, and the user equipment triggers a scheduling request (SR) to request UL authorization; in the one or more special cells, switch the activated UL BWP to a UL BWP, the ULBWP is configured with one or more PRACH opportunities and has not declared the persistent LBT failure; or starts a random access procedure.

In some embodiments, if the RACH procedure is successfully performed, the UE includes the MAC CE of the LBT failure in message 3 (msg3) of the random access procedure. In some embodiments, if the UE successfully transmits a MAC CE of the UL LBT failure to the base station, the UE cancels the one or more MAC CEs configured to trigger the persistent LBT failure. Triggered by one or more MAC CEs of the serving cell. In some embodiments, the one or more MAC CE triggers include the one or more triggered MAC CEs of the UL BWP for one or more special cells SpCell. In some embodiments, the format of the UL LBT failed MAC CE includes at least one of the following: a first format including a bitmap with a size equal to the maximum number of serving cells of the carrier group (CG) and/or a size equal to the A bitmap of the maximum UL BWP number of SpCell; or a second format, including an SCell index where the user equipment fails to declare the persistent LBT and/or a BWP index where the user equipment fails to declare the persistent LBT. In some embodiments, the first format includes a bitmap, the size of the bitmap is equal to the maximum number of PCells plus SCells of one primary cell group (MCG). In some embodiments, the first format includes a bitmap, the size of the bitmap is equal to the maximum number of PSCells of a secondary cell group (SCG) plus multiple SCells. In some embodiments, if the corresponding serving cell declares the persistent LBT failure, the corresponding bit field of the bitmap in the first format is set to 1.

In some embodiments, the first format including the bitmap having a size equal to the maximum number of UL BWPs of the SpCell includes 4 UL BWPs for PCell and 4 UL BWPs for PSCell. In some embodiments, if the corresponding UL BWP of the SpCell declares the persistent LBT failed, the corresponding bit field of the bitmap of the first format is set to 1. In some embodiments, the LBT failure recovery procedure includes a persistent LBT failure recovery procedure, and the persistent LBT failure recovery procedure is configured to the UE through radio resource control (RRC) of the base station. MAC entity. In some embodiments, the persistent LBT failure for each UL BWP is detected by calculating LBT failure indications for all UL transmissions from one or more lower layers of the user equipment to the MAC entity. In some embodiments, the RRC configures at least one of the following parameters in the persistent LBT failure recovery procedure: the maximum count of LBT failure events lbt-FailureInstanceMaxCount for persistent LBT failure detection; or for persistent LBT LBT failure detection timer lbt-FailureDetectionTimer for failure detection. In some embodiments, the following UE variables are used for the persistent LBT failure detection: LBT counter LBT_COUNTER: Counter for LBT failure indication, initially set to 0.

In some embodiments, for each activated serving cell configured with the LBT failure recovery procedure, the MAC entity performs at least one of the following: if the LBT failure indication has been received from the one or more lower layers , the MAC entity starts or restarts the LBT failure detection timer lbt-FailureDetectionTimer and/or increases LBT_COUNTER by 1. In some embodiments, if the LBT_COUNTER is greater than or equal to the LBT failure event maximum count lbt-FailureInstanceMaxCount, the MAC entity declares the persistent LBT failure of the activated UL BWP. In some embodiments, if the serving cell is an SCell, and if there are uplink synchronization channel (UL-SCH) resources available for new transmissions on the serving cell on which the persistent LBT failed has not been triggered, and the The UL-SCH resource can accommodate the UL LBT failed MAC CE plus its subheader. As a result of logical channel priority processing, the MAC entity instructs the multiplexing and assembly entity to generate the UL LBT failed MAC. CE. In some embodiments, if the serving cell is a SCell and if no UL-SCH resources are available for new transmissions on the serving cell that has not yet triggered the persistent LBT failure, the MAC entity Scheduling Request (SR) that triggers the persistent LBT failure. In some embodiments, if the serving cell is a SpCell, and if the persistent LBT failure has been declared in all UL BWPs configured with PRACH opportunities in the SpCell, the MAC entity reports to the user equipment The one or more upper layers indicate that the persistent LBT failed.

In some embodiments, if the serving cell is SpCell, the MAC entity performs at least one of the following: in SpCell, switch the activated UL BWP to the UL BWP, the UL BWP is configured with a PRACH opportunity and the persistent LBT failure for the UL BWP has not yet been declared; performs a BWP operation; or initiates a random access procedure. In some embodiments, if the serving cell is a SpCell, the MAC entity instructs the multiplexing and assembly entity to include the MAC CE for which the LBT failed in the msg3 transmission. In some embodiments, the MAC entity sets the LBT_COUNTER to 0 if the LBT failure detection timer lbt-FailureDetectionTimer or the LBT failure event maximum count lbt-FailureInstanceMaxCount is reconfigured by the one or more upper layers. In some embodiments, the MAC CE for which the LBT failed is identified by a MAC subheader having a logical channel identifier (LCID). In some embodiments, the MAC CE of the LBT failure has a variable size and includes the following fields: C corresponding to C0, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14 and C15; and B0, B1, B2 and B3 corresponding to the BWP index of a PCell or PScell.

LBT operation:

In some embodiments, the lower layer may perform an LBT procedure according to which the lower layer does not perform a transmission if the channel is identified as occupied. When the lower layer performs the LBT procedure before transmission and the transmission is not performed, an LBT failure indication is sent from the lower layer to the MAC entity. Unless otherwise specified, when the LBT procedure is performed for a transmission, the actions specified in this specification shall be performed regardless of whether an LBT failure indication is received from lower layers. When the lower layer does not perform the LBT, no LBT failure indication is received from the lower layer.

In some embodiments, the UE may trigger an uplink LBT failed MAC CE for any serving cell (eg, SCell and/or SpCell) that has triggered an uplink LBT failure. Then, the UE may send a MAC CE that at least has serving cell information of the MAC CE that triggered the uplink LBT failure. If the MAC CE has been transmitted on a serving cell, the UE will cancel all triggered MAC CEs. This can solve the problems in the existing technology, trigger the MAC CE of UL LBT failure for any serving cell that has triggered LBT failure, provide good communication performance, and/or provide high reliability.

The transmitted MAC CE may include all information of the serving cell that has triggered the uplink LBT failure. For example, the MAC CE may report multiple failed cells, and the MAC CE format should support multiple entries to indicate that the sustained All the cells where the UL LBT failed, wherein the UL LBT MAC CE includes one or more cell indices where the UL LBT failure occurred. In addition, since for SpCell (PCell and PSCell), when the UE declares that the UL LBT of the activated UL BWP fails, the UE will switch the activated UL BWP to another UL BWP (this BWP is configured RACH resources). Therefore, the network may need to know the ULBWP information of the SpCell in which the UE announces the UL LBT failure. Therefore, optionally, the UE may also include BWP related information in the MAC CE.

In some embodiments, the above detailed procedures are as follows:

Step 1: If the UE declares that the persistent LBT of the activated UL BWP fails, and if the serving cell is a SCell, the UE instructs the multiplexing and assembly entity to include the If the MAC CE fails the LBT, the uplink transmission should not occur on the SCell that has declared the persistent LBT failure. If there are no available UL resources on the SCell that has not declared the persistent LBT failure, or there are no available UL resources on the SpCell, the UE triggers a Scheduling Request (SR) to request UL grant.

Step 2: If the UE declares that the persistent LBT of the activated UL BWP fails and the serving cell is SpCell:

Step 2.1: If the persistent LBT failure is announced in all UL BWPs configured with PRACH opportunities in the serving cell: the UE indicates the persistent LBT failure to the upper layer.

Step 2.2: Otherwise:

The UE instructs the multiplexing and assembly entity to include the MAC CE for which the LBT failed in subsequent uplink transmissions. Optional behavior. If there are no available UL resources on other serving cells that have not declared persistent LBT failure, the UE triggers a scheduling request to request UL grant. Optionally, in this serving cell, the UE switches the activated ULBWP to a situation where PRACH is configured, and there is no UL BWP announcing the persistent LBT failure, and the UE starts a random access procedure. Optionally, if the RACH procedure can be successfully executed, the UE includes the MAC CE of the LBT failure in message 3 (msg3) of the random access procedure.

Step 3: If the UE successfully transmits the MAC CE of the LBT failure, the UE cancels all the MAC CE triggers of the serving cell that triggered the persistent LBT failure, including those of the UL BWP trigger for SpCell. MACCE.

In some implementations, the format of the MAC CE for LBT failure may be at least one of the following:

Format 1:

The MAC CE of LBT failure includes a bitmap with a size equal to the maximum number of serving cells for one CG, for example, PCell of MCG + multiple SCells and/or PSCell of SCG + multiple SCells. If the corresponding serving cell declares the persistent LBT failure, the corresponding bit field of the bitmap is set to 1. The LBT failed MAC CE also includes a bitmap of size equal to the SpCell's maximum UL BWP number (i.e., 4 for PCell, and 4 for PSCell) if the corresponding UL BWP of the SpCell declares the persistence If the LBT fails, the corresponding bit field of the bitmap is set to 1.

Format 2:

The MAC CE of the LBT failure includes the SCell index of the UE announcing the persistent LBT failure. The MAC CE of the LBT failure includes the BWP index of the UE announcing the persistent LBT failure.

In some implementations, possible implementations of the procedures in the MAC specification are as follows:

LBT failure detection and recovery procedures:

The MAC entity may be configured by RRC to have persistent LBT failure recovery procedures. Persistent LBT failures for each UL BWP are detected by calculating LBT failure indications for all UL transmissions from lower layers to the MAC entity.

RRC configures the following parameters in lbt-FailureRecoveryConfig:

The maximum count of LBT failure events lbt-FailureInstanceMaxCount used for the persistent LBT failure detection;

Use the LBT failure detection timer lbt-FailureDetectionTimer described for persistent LBT failure detection;

The following UE variables are used in the persistent LBT failure detection procedure:

LBT_COUNTER: Counter used for LBT failure indication, initially set to 0.

For each activated serving cell configured with lbt-FailureRecoveryConfig, the MAC entity shall:

1>If the LBT failure indication has been received from the lower layer:

2>Start or restart the LBT failure detection timer lbt-FailureDetectionTimer;

2>Increase LBT_COUNTER by 1;

2>If LBT_COUNTER>=LBT failure event maximum count lbt-FailureInstanceMaxCount:

3> Declare the persistent LBT failure of the activated UL BWP;

3>If this serving cell is a SCell:

4>If there are UL-SCH resources available for new transmission on the serving cell that has not yet triggered the persistent LBT failure, and the UL-SCH resources can accommodate the MAC CE and its subheader of the LBT failure as a logical channel The result of priority processing:

5>Instruct the multiplexing and assembly process to generate the MAC CE for the LBT failure.

4>Otherwise:

3>Trigger a scheduling request for persistent LBT failure.

3>Otherwise (i.e. SpCell):

4>If persistent LBT failure is announced in all UL BWPs configured with PRACH opportunities in this serving cell:

5> Indicate persistent LBT failure to upper management.

4>Otherwise:

5> In the serving cell, switch the activated UL BWP to a UL BWP configured with a PRACH opportunity and without announcing a persistent LBT failure;

5>Perform the BWP operations specified in Article 5.15;

5>Start a random access procedure (as specified in clause 5.1.1).

6>Indicate to the multiplexing and assembly entity that the MACCE that failed to generate the LBT is included in the msg3 transmission. (This can be implemented in the RACH procedure chapter).

Editor's Note: This sentence expresses the conference protocol "If there is another BWP with configured RACH resources, the UE switches to another BWP and starts RACH after declaring persistent LBT failure on PCell or PSCell."

1>If the LBT failure detection timer lbt-FailureDetectionTimer expires; or

1>If the LBT failure detection timer lbt-FailureDetectionTimer or lbt-FailureInstanceMaxCount is reconfigured by the upper layer:

2>Set LBT_COUNTER to 0.

LBT failed MAC:

The MAC for which the LBT failed is identified by a MAC sub-header with an LCID. It is of variable size and consists of the following fields, as shown in Table 1:

Table 1: SCell BFR MAC CE

C7 C6 C5 C4 C3 C2 C1 C0 C15 C14 C13 C12 C11 C10 C9 C8 R R R R B3 B2 B1 B0

C0 to C15 correspond to the serving cells of one CG. B0 to B3 correspond to the BWP index of PCell or PScell.

The MAC CE of LBT failure includes a bitmap with a size equal to the maximum number of serving cells of a CG, for example, PCell of MCG + multiple SCells, PSCell of SCG + multiple SCells. If the corresponding serving cell declares persistent LBT failure, the corresponding bit field of the bitmap is set to 1. The MAC CE of the LBT failure also includes a bitmap, the size of the bitmap is equal to the maximum UL BWP number of the SpCell (i.e. 4 for PCell, 4 for PSCell), if the corresponding UL BWP announcement of the SpCell continues If the LBT fails, the corresponding bit field of the bitmap is set to 1.

Optionally, provide Table 2: SCell BFR MAC CE:

The MAC CE of the LBT failure includes the SCell index of the UE announcing the persistent LBT failure. The MAC CE of the LBT failure includes the BWP index of the UE announcing the persistent LBT failure.

In some embodiments, MAC CE for LBT failure is provided. The MAC CE of the LBT failure is identified by an octet of MAC sub-header with LCID. It has a fixed size and consists of a single octet containing 8 C fields, as shown in Figure 4. In some embodiments, the LBT failed MAC CE of four octets is identified by a MAC subheader with an LCID. It has a fixed size consisting of four octets containing 32 C-fields as shown in Figure 5. When the highest ServCellIndex of the SCell of the MAC entity whose LBT failure is detected is less than 8, a single octet format is used, otherwise a four-octet format is used.

Ci: If there is a serving cell with ServCellIndex I configured for the MAC entity, and if a persistent LBT failure has been triggered in said serving cell and has not been cancelled, then the field is set to 1, otherwise the field is Set to 0.

The business benefits of some embodiments are as follows. 1. Solve the problems in the existing technology. 2. For any serving cell that has triggered LBT failure, trigger UL LBT failure MAC CE. 3. Provide a good communication performance. 4. Provide high reliability. 5. Some embodiments of the present disclosure are applied to 5G-NR chipset suppliers, V2X communication system development suppliers, automobile manufacturers, including cars, trains, trucks, buses, bicycles, motorcycles, helmets, etc., unmanned systems Aerial vehicles (unmanned aerial vehicles), smartphone manufacturers, communication equipment for public safety use, AR/VR equipment manufacturers, such as games, conferences/seminars, educational purposes. Some embodiments of the present disclosure are a combination of "techniques/processes" that can be employed in 3GPP specifications to create the final product. Some implementations of the present disclosure may be adopted in 5G NR unlicensed frequency band communications. Some embodiments of the present disclosure propose technical mechanisms.

Figure 6 is a block diagram of an example system 700 for wireless communications, according to one embodiment of the present disclosure. The embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. Figure 6 illustrates that the system 700 includes radio frequency (RF) circuitry 710, baseband circuitry 720, application circuitry 730, memory/storage 740, display 750, camera 760, sensor 770, and input/output ) interface 780, at least as shown in the figure. The application circuit 730 may include a circuit such as, but not limited to, one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors, such as graphics processors and application processors. The processor may be coupled to the memory/memory and configured to execute instructions stored in the memory/memory to cause various applications and/or operating systems to run on the system.

The baseband circuitry 720 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor may include a baseband processor. The baseband circuitry may handle various radio control functions, enabling communication with one or more radio networks via the radio frequency circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency transfer, etc. In some implementations, the baseband circuitry may provide communications compatible with one or more radio technologies. For example, in some embodiments, the baseband circuit may support communications with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), Communication of wireless local area network (WLAN) and wireless personal area network (WPAN). Implementations in which the baseband circuitry is configured to support radio communications for more than one wireless protocol may be referred to as multi-mode baseband circuitry.

In various implementations, baseband circuitry 720 may include circuitry that operates with signals that are not strictly considered baseband frequencies. For example, in some embodiments, baseband circuitry may include circuitry that operates with signals having intermediate frequencies between the baseband frequency and the radio frequency. The radio frequency circuit 710 may communicate with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various implementations, radio frequency circuitry may include switches, filters, amplifiers, and the like to facilitate communication with a wireless network. In various implementations, the radio frequency circuitry 710 may include circuitry for operating signals that are not strictly considered to be at radio frequencies. For example, in some embodiments, radio frequency circuitry may include circuitry that operates on signals having intermediate frequencies, between baseband frequencies and radio frequencies.

In various embodiments, the transmitter circuitry, control circuitry or receiver circuitry discussed above with respect to user equipment, eNB or gNB may be embodied in whole or in part in one or more of radio frequency circuitry, baseband circuitry and/or application circuitry. indivual. As used herein, "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), electronic circuit, processor (shared, dedicated, or group) and/or execute one or more software or Firmware program memory (shared, dedicated, or group), combinational logic circuitry, and/or other suitable hardware components that provide the functionality described. In some implementations, the electronic device circuitry may be implemented in one or more software or firmware modules, or functions associated with the circuitry may be implemented by one or more software or firmware modules. In some embodiments, the baseband circuit, the application circuit and/or the memory/some or all components of the memory may be implemented together on a System On A Chip (SOC). The memory/memory 740 may be used to load and store data and/or instructions, for example, for the system. Memory/memory for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM), and/or non-volatile memory, such as flash memory.

In various implementations, I/O interface 780 may include one or more user interfaces intended for a user to interact with the system and/or peripheral component interfaces intended for peripheral components to interact with the system. The user interface may include, but is not limited to, a physical keyboard or keypad, touch pad, speakers, microphone, etc. Peripheral component interfaces may include, but are not limited to, non-volatile memory ports, Universal Serial Bus (USB) ports, audio jacks, and power interfaces. In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information relevant to the system. In some embodiments, the sensors may include, but are not limited to, gyroscope sensors, accelerometers, proximity sensors, ambient light sensors, and positioning units. The positioning unit may also be part of or interact with baseband circuitry and/or radio frequency circuitry to communicate with components of a positioning network, such as Global Positioning System (GPS) satellites.

In various implementations, the display 750 may include a display such as a liquid crystal display and a touch screen display. In various implementations, the system 700 may be a mobile computing device, such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an Ultrabook, a smartphone, AR/VR glasses, and the like. In various implementations, the system may have more or fewer components, and/or different architectures. Where appropriate, the methods described herein may be implemented as computer programs. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

Those of ordinary skill in the art understand that each unit, algorithm and step described and disclosed in the embodiments of the present disclosure is implemented using electronic hardware or a software combination of computer and electronic hardware. Whether these functions are run in hardware or software depends on the application conditions and design requirements of the technical solution. Those of ordinary skill in the art can use different ways to implement the functions of each specific application, and such implementation should not exceed the scope of this disclosure. Persons of ordinary skill in the art can understand that since the working processes of the above systems, devices and units are basically the same, reference may be made to the working processes of the systems, devices and units in the above embodiments. For ease of description and simplicity, these working processes will not be described in detail.

It is understood that the systems, devices and methods disclosed in the embodiments of the present invention may be implemented in other ways. The embodiments described are by way of example only. The division of the mentioned units is only based on logical functions, and there may be other division methods during implementation. It is possible for multiple units or elements to be combined or integrated into another system. It is also possible that some features are omitted or skipped. On the other hand, the mutual coupling, direct coupling or communication coupling described or discussed above means coupling through some ports, devices or units, whether indirectly or through communication in electronic, mechanical or other forms.

The elements mentioned above as separate elements for explanation may or may not be physically separate elements. The units mentioned above may be physical units or not, that is, they may be placed in one place or distributed on multiple network units. Some or all of the described elements may be used depending on the purpose of the implementation. Furthermore, each functional unit in each embodiment may be integrated into a processing unit, or physically independent, or integrated into a processing unit with two or more units.

If a software functional unit is implemented and used and sold as a product, it may be stored in a computer-readable storage medium. Based on this understanding, the technical solutions proposed in this disclosure can be implemented essentially or partially in the form of software products. In other words, part of the technical solution that is beneficial to traditional technology can be implemented as a software product. A software product in a computer is stored in a storage medium and includes a plurality of instructions for a computing device (such as a personal computer, a server, or a network device) to execute all or part of the steps disclosed in the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a floppy disk or other types of media that can store program codes.

While the present disclosure has been described in connection with what are considered to be the most practical and preferred embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but is intended to cover all aspects without departing from the appended claims. various arrangements made within the broadest interpretation.

Claims (32)

1. A wireless communication method for user equipment (UE), characterized by comprising: Configure a listen before talk (LBT) failure recovery procedure through the base station; Detect LBT failure for each uplink (UL) bandwidth part (BWP); and triggering a UL LBT failure medium access control (MAC) control element (CE) for the one or more serving cells that triggered the LBT failure; Wherein, the MAC CE includes the format of the MAC CE that fails the UL LBT, and the format of the MAC CE that fails the UL LBT includes a bitmap with a size equal to the maximum number of serving cells of the carrier group (CG) and/or a size equal to a special Bitmap of the maximum number of UL BWPs of the cell (SpCell). 2. The method according to claim 1, further comprising transmitting a MAC CE to the base station, the MAC CE having serving cell information, the serving cell information being configured to trigger the UL LBT failure. MACCE. 3. The method according to claim 2, characterized in that if the MAC CE has been transmitted on the one or more serving cells, the user equipment cancels one or more triggered MAC CEs. 4. The method according to claim 2, characterized in that the serving cell information of the MAC CE includes at least one of the following: Report of a failed neighborhood; A MAC CE format configured to support entries indicating one or more cells that declared the LBT failure; One or more cell indices of the MAC CE where the UL LBT failure occurred; or BWP related information in the MAC CE. 5. The method of claim 1, wherein the uplink transmission does not occur on one or more SCells that have declared the persistent LBT failure. 6. The method according to claim 1, characterized in that if there are no available UL resources on one or more SCells that have not declared the persistent LBT failure and/or on one or more special cells (SpCells) There are no available UL resources on the user equipment, and the user equipment triggers a Scheduling Request (SR) to request UL grant. 7. The method according to claim 1, characterized in that the format of the MAC CE of the UL LBT failure includes the SCell index of the user equipment announcing the persistent LBT failure and/or the user equipment announcing the BWP index for persistent LBT failure. 8. The method according to claim 7, wherein the corresponding serving cell declares the persistent LBT failure and the corresponding bit field of the bitmap is set to 1. 9. A wireless communication method for a base station, characterized in that it includes: Configure listen-before-talk (LBT) failure recovery procedures to user equipment (UE); Controlling the user equipment to detect LBT failure for each uplink (UL) bandwidth part (BWP); and Controlling the user equipment to trigger a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggers LBT failure; Wherein, the MAC CE includes the format of the MAC CE that fails the UL LBT, and the format of the MAC CE that fails the UL LBT includes a bitmap with a size equal to the maximum number of serving cells of the carrier group (CG) and/or a size equal to a special Bitmap of the maximum number of UL BWPs of the cell (SpCell). 10. The method of claim 9, further comprising receiving a MAC CE from the user equipment, the MAC CE having serving cell information, the serving cell information being configured to trigger the UL LBT. Failed MAC CE. 11. The method according to claim 10, characterized in that if the MAC CE has been transmitted on the one or more serving cells, the user equipment cancels one or more triggered MAC CEs. 12. The method according to claim 10, wherein the serving cell information of the MAC CE includes at least one of the following: A report of a failed cell; or A MAC CE format configured to support entries indicating one or more cells that declared the LBT failure; 13. The method of claim 9, wherein the uplink transmission does not occur on one or more SCells that have declared the persistent LBT failure. 14. The method according to claim 13, characterized in that if there are no available UL resources on one or more SCells that have not declared the persistent LBT failure and/or on one or more special cells (SpCells) There are no available UL resources on the user equipment, and the user equipment triggers a Scheduling Request (SR) to request UL grant. 15. The method according to claim 9, characterized in that the format of the MAC CE of the UL LBT failure includes the SCell index of the user equipment announcing the persistent LBT failure and/or the user equipment announcing the BWP index for persistent LBT failure. 16. The method of claim 15, wherein the corresponding serving cell declares the persistent LBT failure and the corresponding bit field of the bitmap is set to 1. 17. A user equipment (UE), characterized by comprising: a memory; a transceiver; and a processor coupled to said memory and said transceiver; Wherein, the processor is configured by the base station to listen before talking (LBT) failure recovery procedure; wherein the processor is configured to detect LBT failure per uplink (UL) bandwidth part (BWP); and wherein the processor is configured to trigger an ULLBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggers LBT failure; Wherein, the MAC CE includes the format of the MAC CE that fails the UL LBT, and the format of the MAC CE that fails the UL LBT includes a bitmap with a size equal to the maximum number of serving cells of the carrier group (CG) and/or a size equal to a special Bitmap of the maximum number of UL BWPs of the cell (SpCell). 18. The user equipment according to claim 17, characterized in that the transceiver is configured to send a MAC CE to the base station, the MAC CE has serving cell information, and the serving cell information is configured to MAC CE that triggers the ULLBT failure. 19. The user equipment of claim 18, wherein if the MAC CE has been transmitted on the one or more serving cells, the processor cancels one or more triggered MAC CEs. 20. The user equipment according to claim 18, characterized in that the serving cell information of the MAC CE includes at least one of the following: Report of a failed neighborhood; A MAC CE format configured to support entries indicating one or more cells that declared the LBT failure; One or more cell indices of the MAC CE where the UL LBT failure occurred; or BWP related information in the MAC CE. 21. The user equipment according to claim 17, characterized in that the uplink transmission does not occur on one or more SCells that have declared the persistent LBT failure. 22. The user equipment according to claim 17, characterized in that if there are no available UL resources on one or more SCells that have not declared the persistent LBT failure and/or on one or more special cells (SpCell ), the processor triggers a Scheduling Request (SR) to request UL grant. 23. The user equipment according to claim 17, characterized in that the format of the MAC CE of the UL LBT failure includes the SCell index of the user equipment announcing the persistent LBT failure and/or the SCell index announced by the user equipment. BWP index describing persistent LBT failures. 24. The user equipment according to claim 23, wherein the corresponding serving cell declares the persistent LBT failure, and the corresponding bit field of the bitmap is set to 1. 25. A base station, characterized in that it includes: a memory; a transceiver; and a processor coupled to said memory and said transceiver; Wherein, the processor is configured to configure a listen before talk (LBT) failure recovery procedure to the user equipment (UE); wherein the processor is configured to control the user equipment to detect LBT failure per uplink (UL) bandwidth part (BWP); and wherein the processor is configured to control the user equipment to trigger a UL LBT failure medium access control (MAC) control element (CE) for one or more serving cells that triggers LBT failure; Wherein, the MAC CE includes the format of the MAC CE that fails the UL LBT, and the format of the MAC CE that fails the UL LBT includes a bitmap with a size equal to the maximum number of serving cells of the carrier group (CG) and/or a size equal to a special Bitmap of the maximum number of UL BWPs of the cell (SpCell). 26. The base station according to claim 25, wherein the transceiver is configured to receive MAC CE from the user equipment, the MAC CE has serving cell information, and the serving cell information is configured to MAC CE that triggers the ULLBT failure. 27. The base station according to claim 26, wherein if the MAC CE has been transmitted on the one or more serving cells, the user equipment cancels one or more triggered MAC CEs. 28. The base station according to claim 26, wherein the serving cell information of the MAC CE includes at least one of the following: Report of a failed neighborhood; A MAC CE format configured to support entries indicating one or more cells that declared the LBT failure; One or more cell indices of the MAC CE where the UL LBT failure occurred; or BWP related information in the MAC CE. 29. The base station of claim 25, wherein the uplink transmission does not occur on one or more SCells that have declared the persistent LBT failure. 30. The base station according to claim 25, characterized in that if there are no available UL resources on one or more SCells that have not declared the persistent LBT failure and/or on one or more special cells (SpCells) There are no available UL resources on the user equipment, and the user equipment triggers a Scheduling Request (SR) to request UL grant. 31. The base station according to claim 25, wherein the format of the MAC CE of the UL LBT failure includes the SCell index of the user equipment announcing the persistent LBT failure and/or the user equipment announcing the BWP index for persistent LBT failure. 32. The base station according to claim 31, wherein the corresponding serving cell declares the persistent LBT failure and the corresponding bit field of the bitmap is set to 1.