Patent Publication Number: US-2023164834-A1

Title: Incrementing a transmission counter in response to lbt failure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 63/013,186 entitled “RACH/SR COUNTER HANDLING IN CASE OF LBT FAILURE” and filed on Apr. 21, 2020 for Joachim Loehr, Alexander Johann Maria Golitschek Edler von Elbwart, and Ravi Kuchibhotla, which application is incorporated herein by reference. 
    
    
     FIELD 
     The subject matter disclosed herein relates generally to wireless communications and more particularly relates to handling consistent Listen-Before-Talk (“LBT”) failure for the case of spatial multiplexed communications. 
     BACKGROUND 
     In certain wireless communication systems, service is supplemented by operation on unlicensed spectrum. However, operation on unlicensed spectrum requires Clear Channel Assessment (“CCA”) prior to transmission, for example involving a Listen-Before-Talk (“LBT”) procedure. 
     In Third generation Partnership Project (“3GPP”) New Radio in Unlicensed Spectrum (“NR-U”), channel access in both downlink (“DL”) and uplink (“UL”) relies on the CCA (e.g., LBT procedure) to gain channel access. Prior to any transmission, the gNB (i.e., 5th generation (“5G”) base station) and/or the User Equipment (“UE”) must first sense the channel to find out whether there are ongoing communications on the channel No beamforming is considered for LBT in NR-U in Release 16 (“Rel-16”) and only omni-directional LBT is assumed. 
     BRIEF SUMMARY 
     Disclosed are procedures for counter handling in case of LBT failure. Said procedures may be implemented by apparatus, systems, methods, or computer program products. 
     One method of a User Equipment device (“UE”) includes performing a Listen-Before-Talk (“LBT”) procedure for a transmission and detecting LBT failure for the transmission. The first method includes determining whether a Medium Access Control (“MAC”) entity of the UE is configured with a consistent LBT failure recovery procedure. If the MAC entity of the UE is not configured with the consistent LBT failure recovery procedure, the first method includes incrementing a transmission counter without transmission of an uplink transmission in response to an indication of the LBT failure. 
     Another method of a UE includes performing a LBT procedure for a transmission and detecting LBT failure for the transmission. The second method includes determining whether consistent LBT failure recovery functionality is supported at the UE. If the UE does not support consistent LBT failure recovery functionality, the second method includes indicating an LBT success by to a MAC entity of the UE without performing a corresponding uplink transmission in response to the LBT failure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
         FIG.  1    is a schematic block diagram illustrating one embodiment of a wireless communication system for counter handling in case of LBT failure; 
         FIG.  2    is a block diagram illustrating one embodiment of a 5G New Radio (“NR”) protocol stack; 
         FIG.  3    is a diagram illustrating one embodiment of a radio frame during which LBT procedure is performed; 
         FIG.  4    is a diagram illustrating one embodiment of a procedure for RACH counter handling in case of LBT failure; 
         FIG.  5    is a diagram illustrating one embodiment of an alternative procedure for RACH counter handling in the case of LBT failure; 
         FIG.  6    is a diagram illustrating one embodiment of another procedure for RACH counter handling in case of LBT failure; 
         FIG.  7    is a diagram illustrating one embodiment of an implementation of RACH counter handling in case of LBT failure; 
         FIG.  8    is a diagram illustrating one embodiment of a procedure for SR counter handling in case of LBT failure; 
         FIG.  9    is a diagram illustrating one embodiment of an alternative procedure for SR counter handling in the case of LBT failure; 
         FIG.  10    is a diagram illustrating one embodiment of another procedure for SR counter handling in case of LBT failure; 
         FIG.  11    is a diagram illustrating one embodiment of a user equipment apparatus that may be used for counter handling in case of LBT failure; 
         FIG.  12    is a diagram illustrating one embodiment of a network apparatus that may be used for counter handling in case of LBT failure; 
         FIG.  13    is a flowchart diagram illustrating one embodiment of a first method for counter handling in case of LBT failure; and 
         FIG.  14    is a flowchart diagram illustrating one embodiment of a second method for counter handling in case of LBT failure. 
     
    
    
     DETAILED DESCRIPTION 
     As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects. 
     For example, the disclosed embodiments may be implemented as a hardware circuit comprising custom very-large-scale integration (“VLSI”) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like. As another example, the disclosed embodiments may include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function. 
     Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and/or program code, referred hereafter as code. The storage devices may be tangible, non-transitory, and/or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code. 
     Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. 
     More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (“RAM”), a read-only memory (“ROM”), an erasable programmable read-only memory (“EPROM” or Flash memory), a portable compact disc read-only memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object-oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the “C” programming language, or the like, and/or machine languages such as assembly languages. The code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (“LAN”), wireless LAN (“WLAN”), or a wide area network (“WAN”), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider (“ISP”)). 
     Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment. 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise. 
     As used herein, a list with a conjunction of “and/or” includes any single item in the list or a combination of items in the list. For example, a list of A, B and/or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C. As used herein, a list using the terminology “one or more of” includes any single item in the list or a combination of items in the list. For example, one or more of A, B and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C. As used herein, a list using the terminology “one of” includes one and only one of any single item in the list. For example, “one of A, B and C” includes only A, only B or only C and excludes combinations of A, B and C. As used herein, “a member selected from the group consisting of A, B, and C,” includes one and only one of A, B, or C, and excludes combinations of A, B, and C.” As used herein, “a member selected from the group consisting of A, B, and C and combinations thereof” includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C or a combination of A, B and C. 
     Aspects of the embodiments are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by code. This code may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart diagrams and/or block diagrams. 
     The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function/act specified in the flowchart diagrams and/or block diagrams. 
     The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart diagrams and/or block diagrams. 
     The flowchart diagrams and/or block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods, and program products according to various embodiments. In this regard, each block in the flowchart diagrams and/or block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function(s). 
     It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures. 
     Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code. 
     The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements. 
     Generally, the present disclosure describes systems, methods, and apparatus for counter handling in case of Listen-Before-Talk (“LBT”) failure. In NR-U, channel access in both downlink and uplink relies on the LBT; however, no beamforming is considered for LBT in NR-U in Rel-16 and only omni-directional LBT is assumed. A MAC layer entity of the UE relies on reception of a notification of UL LBT failure from the Physical layer to detect a consistent UL LBT failure. The NR-U LBT procedures for channel access can be summarized as follows: 
     A) Both gNB-initiated and UE-initiated Channel Occupant Times (“COTs”) use Category 4 (“Cat-4”) LBT where the start of a new transmission burst always perform LBT with exponential back-off. Only with exception, when the DRS must be at most one ms in duration and is not multiplexed with unicast PDSCH. As used herein, a Cat-4 LBT procedure refers to LBT with a random back-off and with a variable size contention window. 
     B) UL transmission within a gNB initiated Channel Occupancy Time (“COT”) or a subsequent DL transmission within a UE or gNB initiated COT can transmit immediately without sensing only if the gap from the end of the previous transmission is not more than 16 μs, otherwise Category 2 (“Cat-2”) LBT must be used, and the gap cannot exceed 25 μs. As used herein, a Cat-2 LBT procedure refers to LBT without random back-off. 
     According to 3GPP TS 38.321, the transmission counter PREAMBLE_POWER_RAMPING_COUNTER is to be incremented every time a new PRACH preamble is transmitted as long as the corresponding SSB or CSI-RS selected does not change and LBT failure has not occurred in the previous transmission. This last part ensures that the power ramping is not applied due to LBT failures. 
     A first problem addressed by the present disclosure relates to how to handle RACH counters when consistent LBT failures happen. According to the current specified behavior, the RACH counter PREAMBLE_TRANSMISSION_COUNTER will be stuck at the same value. In order to solve such deadlock situation, the consistent LBT detection and recovery procedure was introduced. However, the LBT failure detection and recovery is an optional UE capability/feature. Therefore, when the UE does not support this mechanism or the network does not configure the consistent LBT failure detection and recovery procedure, there will not be a recovery if RACH attempts fail consistently, i.e., the UE will not inform RRC layer about the RACH problem and trigger RLF, since counter never reaches the configured maximum value preambleTransMax. 
     A second problem addressed by the present disclosure relates to the transmission of Scheduling Request (“SR”) on Physical Uplink Control Channel (“PUCCH”). In case of consistent LBT failure, the higher layer (e.g., RRC layer) is not informed about the link problem and random access procedure is not triggered, since the SR counter is not increased and hence sr-TransMax is not exceeded. 
     To solve the above problems with the current state of the art, the following UE behavior may be implemented: 
     UE behavior with respect to RACH counter handling depends on the UE capability and depends on whether the network configures the UE with consistent LBT failure recovery procedure. When the UE does not support the LBT detection and recovery functionality or when the UE is not configured with a consistent LBT failure recovery procedure, then the UE is to increment the RACH counter (e.g., PREAMBLE_TRANSMISSION_COUNTER) if the preamble is not transmitted due to LBT failure. However, for cases when the UE does support the consistent LBT failure recovery procedure and the UE MAC layer entity is configured by network with the consistent LBT failure recovery procedure, then the UE does not increment the RACH counter (e.g., PREAMBLE_TRANSMISSION_COUNTER) if the preamble is not transmitted due to LBT failure 
     The UE behavior with respect to SR counter handling depends on the UE capability and depends on whether the network configures the UE with consistent LBT failure recovery procedure. When the UE does not support the LBT detection and recovery functionality or when the UE is not configured with a consistent LBT failure recovery procedure, then the UE is to increment the SR transmission counter (e.g., SR_COUNTER) if the preamble is not transmitted due to LBT failure. For cases when UE does support the consistent LBT failure recovery procedure and the UE/MAC is configured by network with the consistent LBT failure recovery procedure, the UE does not increment the SR_COUNTER if the preamble is not transmitted due to LBT failure 
     In certain embodiments, the PHY layer of a UE indicates an LBT success to the MAC layer for cases when the consistent LBT failure recovery procedure is not used by the UE even for cases when the Random access preamble transmission cannot be performed due to LBT failure. 
       FIG.  1    depicts a wireless communication system  100  for counter handling in case of LBT failure, according to embodiments of the disclosure. In one embodiment, the wireless communication system  100  includes at least one remote unit  105 , a radio access network (“RAN”)  120 , and a mobile core network  140 . The RAN  120  and the mobile core network  140  form a mobile communication network. The RAN  120  may be composed of a base unit  121  with which the remote unit  105  communicates using wireless communication links  123 . Even though a specific number of remote units  105 , base units  121 , wireless communication links  123 , RANs  120 , and mobile core networks  140  are depicted in  FIG.  1   , one of skill in the art will recognize that any number of remote units  105 , base units  121 , wireless communication links  123 , RANs  120 , and mobile core networks  140  may be included in the wireless communication system  100 . 
     In one implementation, the RAN  120  is compliant with the 5G system specified in the 3GPP specifications. For example, the RAN  120  may be a NG-RAN, implementing NR RAT and/or LTE RAT. In another example, the RAN  120  may include non-3GPP RAT (e.g., Wi-Fi® or Institute of Electrical and Electronics Engineers (“IEEE”) 802.11-family compliant WLAN). In another implementation, the RAN  120  is compliant with the LTE system specified in the 3GPP specifications. More generally, however, the wireless communication system  100  may implement some other open or proprietary communication network, for example Worldwide Interoperability for Microwave Access (“WiMAX”) or IEEE 802.16-family standards, among other networks. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. 
     In one embodiment, the remote units  105  may include computing devices, such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), smart appliances (e.g., appliances connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), or the like. In some embodiments, the remote units  105  include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units  105  may be referred to as the UEs, subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, user terminals, wireless transmit/receive unit (“WTRU”), a device, or by other terminology used in the art. In various embodiments, the remote unit  105  includes a subscriber identity and/or identification module (“SIM”) and the mobile equipment (“ME”) providing mobile termination functions (e.g., radio transmission, handover, speech encoding and decoding, error detection and correction, signaling and access to the SIM). In certain embodiments, the remote unit  105  may include a terminal equipment (“TE”) and/or be embedded in an appliance or device (e.g., a computing device, as described above). 
     The remote units  105  may communicate directly with one or more of the base units  121  in the RAN  120  via uplink (“UL”) and downlink (“DL”) communication signals. Furthermore, the UL and DL communication signals may be carried over the wireless communication links  123 . Here, the RAN  120  is an intermediate network that provides the remote units  105  with access to the mobile core network  140 . As described in greater detail below, the remote unit  105  may send directional RACH and/or SR transmissions  125  to the base unit  121 . 
     In some embodiments, the remote units  105  communicate with an application server  151  via a network connection with the mobile core network  140 . For example, an application  107  (e.g., web browser, media client, telephone and/or Voice-over-Internet-Protocol (“VoIP”) application) in a remote unit  105  may trigger the remote unit  105  to establish a protocol data unit (“PDU”) session (or other data connection) with the mobile core network  140  via the RAN  120 . The mobile core network  140  then relays traffic between the remote unit  105  and the application server  151  in the packet data network  150  using the PDU session. The PDU session represents a logical connection between the remote unit  105  and the User Plane Function (“UPF”)  141 . 
     In order to establish the PDU session (or PDN connection), the remote unit  105  must be registered with the mobile core network  140  (also referred to as “attached to the mobile core network” in the context of a Fourth Generation (“4G”) system). Note that the remote unit  105  may establish one or more PDU sessions (or other data connections) with the mobile core network  140 . As such, the remote unit  105  may have at least one PDU session for communicating with the packet data network  150 . The remote unit  105  may establish additional PDU sessions for communicating with other data networks and/or other communication peers. 
     In the context of a 5G system (“5GS”), the term “PDU Session” refers to a data connection that provides end-to-end (“E2E”) user plane (“UP”) connectivity between the remote unit  105  and a specific Data Network (“DN”) through the UPF  141 . A PDU Session supports one or more Quality of Service (“QoS”) Flows. In certain embodiments, there may be a one-to-one mapping between a QoS Flow and a QoS profile, such that all packets belonging to a specific QoS Flow have the same 5G QoS Identifier (“5QI”). 
     In the context of a 4G/LTE system, such as the Evolved Packet System (“EPS”), a Packet Data Network (“PDN”) connection (also referred to as EPS session) provides E2E UP connectivity between the remote unit and a PDN. The PDN connectivity procedure establishes an EPS Bearer, i.e., a tunnel between the remote unit  105  and a Packet Gateway (“PGW”, not shown) in the mobile core network  140 . In certain embodiments, there is a one-to-one mapping between an EPS Bearer and a QoS profile, such that all packets belonging to a specific EPS Bearer have the same QoS Class Identifier (“QCI”). 
     The base units  121  may be distributed over a geographic region. In certain embodiments, a base unit  121  may also be referred to as an access terminal, an access point, a base, a base station, a Node-B (“NB”), an Evolved Node B (abbreviated as eNodeB or “eNB,” also known as Evolved Universal Terrestrial Radio Access Network (“E-UTRAN”) Node B), a 5G/NR Node B (“gNB”), a Home Node-B, a relay node, a RAN node, or by any other terminology used in the art. The base units  121  are generally part of a RAN, such as the RAN  120 , that may include one or more controllers communicably coupled to one or more corresponding base units  121 . These and other elements of radio access network are not illustrated but are well known generally by those having ordinary skill in the art. The base units  121  connect to the mobile core network  140  via the RAN  120 . 
     The base units  121  may serve a number of remote units  105  within a serving area, for example, a cell or a cell sector, via a wireless communication link  123 . The base units  121  may communicate directly with one or more of the remote units  105  via communication signals. Generally, the base units  121  transmit DL communication signals to serve the remote units  105  in the time, frequency, and/or spatial domain. Furthermore, the DL communication signals may be carried over the wireless communication links  123 . The wireless communication links  123  may be any suitable carrier in licensed or unlicensed radio spectrum. The wireless communication links  123  facilitate communication between one or more of the remote units  105  and/or one or more of the base units  121 . Note that during NR-U operation, the base unit  121  and the remote unit  105  communicate over unlicensed radio spectrum. 
     In one embodiment, the mobile core network  140  is a 5GC or an Evolved Packet Core (“EPC”), which may be coupled to a packet data network  150 , like the Internet and private data networks, among other data networks. A remote unit  105  may have a subscription or other account with the mobile core network  140 . Each mobile core network  140  belongs to a single PLMN. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. 
     The mobile core network  140  includes several network functions (“NFs”). As depicted, the mobile core network  140  includes at least one UPF  141 . The mobile core network  140  also includes multiple control plane (“CP”) functions including, but not limited to, an Access and Mobility Management Function (“AMF”)  143  that serves the RAN  120 , a Session Management Function (“SMF”)  145 , a Policy Control Function (“PCF”)  147 , and a Unified Data Management function (“UDM”). In some embodiments, the UDM is co-located with a User Data Repository (“UDR”), depicted as combined entity “UDM/UDR”  149 . In various embodiments, the mobile core network  140  may also include an Authentication Server Function (“AUSF”), a Network Repository Function (“NRF”) (used by the various NFs to discover and communicate with each other over Application Programming Interfaces (“APIs”)), or other NFs defined for the 5GC. In certain embodiments, the mobile core network  140  may include an authentication, authorization, and accounting (“AAA”) server. 
     In various embodiments, the mobile core network  140  supports different types of mobile data connections and different types of network slices, wherein each mobile data connection utilizes a specific network slice. Here, a “network slice” refers to a portion of the mobile core network  140  optimized for a certain traffic type or communication service. A network instance may be identified by a single-network slice selection assistance information (“S-NSSAI”) while a set of network slices for which the remote unit  105  is authorized to use is identified by network slice selection assistance information (“NSSAI”). Here, “NSSAI” refers to a vector value including one or more S-NSSAI values. In certain embodiments, the various network slices may include separate instances of network functions, such as the SMF  145  and UPF  141 . In some embodiments, the different network slices may share some common network functions, such as the AMF  143 . The different network slices are not shown in  FIG.  1    for ease of illustration, but their support is assumed. 
     Although specific numbers and types of network functions are depicted in  FIG.  1   , one of skill in the art will recognize that any number and type of network functions may be included in the mobile core network  140 . Moreover, in an LTE variant where the mobile core network  140  is an EPC, the depicted network functions may be replaced with appropriate EPC entities, such as a Mobility Management Entity (“MME”), a Serving Gateway (“SGW”), a PGW, a Home Subscriber Server (“HSS”), and the like. For example, the AMF  143  may be mapped to an MME, the SMF  145  may be mapped to a control plane portion of a PGW and/or to an MME, the UPF  141  may be mapped to an SGW and a user plane portion of the PGW, the UDM/UDR  149  may be mapped to an HSS, etc. 
     While  FIG.  1    depicts components of a 5G RAN and a 5G core network, the described embodiments for counter handling in case of LBT failure apply to other types of communication networks and RATs, including IEEE 802.11 variants, Global System for Mobile Communications (“GSM”, i.e., a 2G digital cellular network), General Packet Radio Service (“GPRS”), Universal Mobile Telecommunications System (“UMTS”), LTE variants, CDMA 2000, Bluetooth, ZigBee, Sigfox, and the like. 
     In the following descriptions, the term “RAN node” is used for the base station but it is replaceable by any other radio access node, e.g., gNB, eNB, Base Station (“BS”), Access Point (“AP”), etc. Further, the operations are described mainly in the context of 5G NR. However, the proposed solutions/methods are also equally applicable to other mobile communication systems supporting counter handling in case of LBT failure. 
       FIG.  2    depicts a NR protocol stack  200 , according to embodiments of the disclosure. While  FIG.  2    shows the UE  205 , the RAN node  210  and an AMF  215  in a 5G core network (“5GC”), these are representative of a set of remote units  105  interacting with a base unit  121  and a mobile core network  140 . As depicted, the protocol stack  200  comprises a User Plane protocol stack  201  and a Control Plane protocol stack  203 . The User Plane protocol stack  201  includes a physical (“PHY”) layer  220 , a Medium Access Control (“MAC”) sublayer  225 , the Radio Link Control (“RLC”) sublayer  230 , a Packet Data Convergence Protocol (“PDCP”) sublayer  235 , and Service Data Adaptation Protocol (“SDAP”) layer  240 . The Control Plane protocol stack  203  includes a physical layer  220 , a MAC sublayer  225 , a RLC sublayer  230 , and a PDCP sublayer  235 . The Control Plane protocol stack  203  also includes a Radio Resource Control (“RRC”) layer  245  and a Non-Access Stratum (“NAS”) layer  250 . 
     The AS layer (also referred to as “AS protocol stack”) for the User Plane protocol stack  201  consists of at least SDAP, PDCP, RLC and MAC sublayers, and the physical layer. The AS layer for the Control Plane protocol stack  203  consists of at least RRC, PDCP, RLC and MAC sublayers, and the physical layer. The Layer-2 (“L2”) is split into the SDAP, PDCP, RLC and MAC sublayers. The Layer-3 (“L3”) includes the RRC sublayer  245  and the NAS layer  250  for the control plane and includes, e.g., an Internet Protocol (“IP”) layer and/or PDU Layer (not depicted) for the user plane. L1 and L2 are referred to as “lower layers,” while L3 and above (e.g., transport layer, application layer) are referred to as “higher layers” or “upper layers.” 
     The physical layer  220  offers transport channels to the MAC sublayer  225 . The physical layer  220  may perform CCA/LBT procedure using energy detection thresholds, as described herein. In certain embodiments, the physical layer  220  may send a notification of UL LBT failure to a MAC entity at the MAC sublayer  225 . The MAC sublayer  225  offers logical channels to the RLC sublayer  230 . The RLC sublayer  230  offers RLC channels to the PDCP sublayer  235 . The PDCP sublayer  235  offers radio bearers to the SDAP sublayer  240  and/or RRC layer  245 . The SDAP sublayer  240  offers QoS flows to the core network (e.g., 5GC). The RRC layer  245  provides for the addition, modification, and release of Carrier Aggregation and/or Dual Connectivity. The RRC layer  245  also manages the establishment, configuration, maintenance, and release of Signaling Radio Bearers (“SRBs”) and Data Radio Bearers (“DRBs”). 
     The NAS layer  250  is between the UE  205  and the 5GC  215 . NAS messages are passed transparently through the RAN. The NAS layer  250  is used to manage the establishment of communication sessions and for maintaining continuous communications with the UE  205  as it moves between different cells of the RAN. In contrast, the AS layer is between the UE  205  and the RAN (i.e., RAN node  210 ) and carries information over the wireless portion of the network. 
     A UE may use various transmission counters, including a RACH transmission counter and a SR transmission counter. One example of a RACH transmission counter is the PREAMBLE_TRANSMISSION_COUNTER which starts from 1 (at the first PRACH transmission) and gets incremented by 1 each time PRACH is retransmitted. As defined in 3GPP TS 38.321, PREAMBLE_TRANSMISSION_COUNTER is used to detect and declare RACH failure. It is incremented when a RA response is not received within ra-Response Window duration. When the counter reaches the configured maximum value (preambleTransMax+1), random access failure is declared and either RLF (on MCG) or SCG failure occurs. 
     Since ra-Response Window only starts with actual msg1 or msgA transmission, it is not started when these transmission fail due to LBT failures. Therefore, when consistent LBT failures happen, PREAMBLE_TRANSMISSION_COUNTER will be stuck at the same value. When RAN2 made the agreement on PREAMBLE_TRANSMISSION_COUNTER, it was assumed that consistent UL LBT failure detection and recovery mechanism will kick in and break the deadlock due to counter being stuck. 
     One example of a SR transmission counter is SR_COUNTER which also starts from 1 (at the first SR transmission) and gets incremented by 1 each time SR is retransmitted. SR_COUNTER may be used to detect and declare SR failure, e.g., where a maximum number of SR transmissions (i.e., sr-TransMax) has been reached. 
     The problems/issues mentioned above may be solved by making it mandatory that a remote unit  105  supports the consistent LBT failure recovery procedure. It should be also noted that the consistent LBT failure recovery procedure has been designed in a way that it is more efficient compared to the legacy RLF procedure, i.e., RLF may be triggered too early when relying on the legacy procedures which are not optimized for NR-U/LBT. However, even the mandatory support/capability may not be sufficient, as also the network needs to support and configure it. Therefore, the following solutions describe counter handling in the case of LBT failure that considers a UE&#39;s ability to support the consistent LBT failure recovery procedure. 
       FIG.  3    depicts an LBT procedure  300  for a radio frame  305  for unlicensed communication, according to embodiments of the disclosure. When a communication channel is a wide bandwidth unlicensed carrier  310  (e.g., several hundred MHz, the CCA/LBT procedure relies on detecting the energy level on multiple sub-bands  315  of the communications channel as shown in  FIG.  3   . The LBT parameters (such as type/duration, clear channel assessment parameters, etc.) may be configured in the UE  205  by the RAN node  210 . In one embodiment, the LBT procedure is performed at the PHY layer  220 . 
     When performing omni-directional LBT, the entity (i.e., UE or RAN node) may use an omnidirectional sensing beam. Alternatively, the entity may simultaneously perform directional LBT using multiple beams (i.e., corresponding to multiple device panels) in order to simulate omnidirectional sensing. When performing directional LBT, the entity (i.e., UE or RAN node) performs LBT for a given beam (i.e., corresponding to a given spatial direction). Note that each directional beam may correspond to one or more device panels. 
       FIG.  3    also depicts frame structure of the radio frame  305  for unlicensed communication between the UE  205  and RAN node  210 . The radio frame  305  may be divided into subframes (indicated by subframe boundaries  320 ) and may be further divided into slots (indicated by slot boundaries  325 ). The radio frame  305  uses a flexible arrangements where uplink and downlink operations are on the same frequency channel but are separated in time. However, the subframes are not configured as a downlink subframe or an uplink subframe and a particular subframe may be used by either the UE  205  or RAN node  210 . As discussed previously, LBT is performed prior to a transmission. Where LBT does not coincide with a slot boundary  325 , a reservation signal  330  may be transmitted to reserve (i.e., occupy) the channel until the slot boundary is reached and data transmission begins. 
       FIG.  4    depicts a procedure  400  for RACH counter handling in case of LBT failure, according to embodiments of the first solution. The procedure  400  is performed by a UE operating in a mobile communication network, such as the UE  205 . According to a first solution, the UE behavior with respect to the RACH counter handling, e.g., PREAMBLE_TRANSMISSION_COUNTER, depends on the UE capability, i.e., whether the UE  205  supports LBT failure detection and recovery procedure. 
     For cases where the UE  205  does not support the LBT detection and recovery functionality, i.e., where the UE capability indicates that the functionality is not supported, the UE  205  increments the PREAMBLE_TRANSMISSION_COUNTER if the preamble is not transmitted due to LBT failure, i.e., where an LBT failure is indicated by the PHY layer  220  for the PRACH preamble transmission. 
     For cases where the UE  205  does support the LBT detection and recovery procedure, the UE  205  does not increment the PREAMBLE_TRANSMISSION_COUNTER if the preamble is not transmitted due to LBT failure. 
     As depicted, the procedure  400  begins as the UE  205  detects that PRACH preamble was not transmitted due to LBT failure (see block  405 ). The UE  205  determines whether it supports (i.e., has the capability for) LBT detection and recovery (see decision block  410 ). If yes, then the UE  205  does not increment the RACH counter (i.e., PREAMBLE_TRANSMISSION_COUNTER) when the preamble is not transmitted due to LBT failure (see block  415 ). Otherwise, if the UE  205  does not support LBT detection and recovery (i.e., also referred to as consistent LBT failure recovery procedure), then the UE  205  increments the RACH counter when the preamble is not transmitted due to LBT failure (see block  420 ). 
       FIG.  5    depicts a procedure  500  for RACH counter handling in case of LBT failure, according to embodiments of the second solution. The procedure  500  is performed by a UE operating in a mobile communication network, such as the UE  205 . According to the second solution, the UE behavior with respect to RACH counter handling depends on whether the UE  205  has been configured with the consistent LBT failure recovery procedure, e.g., whether parameter lbt-FailureRecoveryConfig is configured. 
     For cases where a MAC entity of the UE  205  is not configured by RRC with a consistent LBT failure recovery procedure, the UE  205  increments the PREAMBLE_TRANSMISSION_COUNTER if the preamble is not transmitted due to LBT failure, i.e., where an LBT failure is indicated by the PHY layer  220  for the PRACH preamble transmission. 
     For cases where the UE/MAC is configured by network with the consistent LBT failure recovery procedure, if the preamble is not transmitted due to LBT failure, then the UE  205  does not increment the PREAMBLE_TRANSMISSION_COUNTER. 
     As depicted, the procedure  500  begins as the UE  205  detects that PRACH preamble was not transmitted due to LBT failure (see block  505 ). The UE  205  determines whether the MAC entity is configured with consistent LBT failure recovery procedure (see decision block  510 ). If the MAC entity is configured with consistent LBT failure recovery procedure (e.g., parameter lbt-FailureRecoveryConfig is configured), then the UE  205  does not increment the RACH counter (i.e., PREAMBLE_TRANSMISSION_COUNTER) when the preamble is not transmitted due to LBT failure (see block  515 ). Otherwise, if the MAC entity is not configured with consistent LBT failure recovery procedure, then the UE  205  increments the RACH counter when the preamble is not transmitted due to LBT failure (see block  520 ). 
       FIG.  6    depicts a procedure  600  for RACH counter handling in case of LBT failure, according to embodiments of the third solution. The procedure  600  is performed by a UE operating in a mobile communication network, such as the UE  205 . According to the second solution, the UE behavior with respect to RACH counter handling does not depend only on the UE capability for LBT detection and recovery, but also depends on whether the UE  205  has been configured with the consistent LBT failure recovery procedure, e.g., whether parameter lbt-FailureRecoveryConfig is configured. 
     For cases where the UE  205  does not support the LBT detection and recovery functionality, (i.e., also referred to as consistent LBT failure recovery procedure), or where the MAC entity is not configured by RRC with a consistent LBT failure recovery procedure, the UE  205  increments the PREAMBLE_TRANSMISSION_COUNTER if the preamble is not transmitted due to LBT failure, i.e., where an LBT failure is indicated by the PHY layer  220  for the PRACH preamble transmission. 
     For cases where the UE  205  does support the consistent LBT failure recovery procedure and where the UE/MAC is configured by network with the consistent LBT failure recovery procedure, if the preamble is not transmitted due to LBT failure, then the UE  205  does not increment the PREAMBLE_TRANSMISSION_COUNTER. 
     As depicted, the procedure  600  begins as the UE  205  detects that PRACH preamble was not transmitted due to LBT failure (see block  605 ). The UE  205  determines whether it supports (i.e., has the capability for) LBT detection and recovery (see decision block  610 ). If yes, then the UE  205  determines whether the MAC entity is configured with consistent LBT failure recovery procedure (see decision block  615 ). If the UE  205  both supports LBT detection and recovery (i.e., also referred to as consistent LBT failure recovery procedure) and the MAC entity is configured with consistent LBT failure recovery procedure (e.g., parameter lbt-FailureRecoveryConfig is configured), then the UE  205  does not increment the RACH counter (i.e., PREAMBLE_TRANSMISSION_COUNTER) when the preamble is not transmitted due to LBT failure (see block  620 ). Otherwise, if the UE  205  does not support LBT detection and recovery—or if the MAC entity is not configured with consistent LBT failure recovery procedure, then the UE  205  increments the RACH counter when the preamble is not transmitted due to LBT failure (see block  625 ). 
       FIG.  7    shows proposed text  700  outlining one implementation  705  of the third solution. As depicted, the 3GPP specifications relating to Random Access Preamble transmission (i.e., described in clause 5.1.3 of 3GPP TS 38.321). According to the implementation  705 , if the PREAMBLE_TRANSMISSION_COUNTER is greater than one and if an LBT failure indication is received from lower layers for the last PRACH preamble transmission, then the UE may increment the PREAMBLE_TRANSMISSION_COUNTER by one, based on whether the UE supports and/or is configured with the consistent LBT failure recovery procedure. 
       FIG.  8    depicts a procedure  800  for SR transmission counter handling in case of LBT failure, according to embodiments of the fourth solution. The procedure  800  is performed by a UE operating in a mobile communication network, such as the UE  205 . According to the third solution, the UE behavior with respect to the SR transmission counter handling (e.g., SR_COUNTER) depends on the UE capability, i.e., whether the UE  205  supports LBT failure detection and recovery procedure. 
     For cases where the UE  205  does not support the LBT detection and recovery functionality (i.e., where the UE capability indicates that the functionality is not supported), the UE  205  increments the SR transmission counter (e.g., SR_COUNTER) if the SR (e.g., on PUCCH) is not transmitted due to LBT failure, i.e., where an LBT failure is indicated by PHY layer  220  for the SR transmission. 
     For cases where the UE  205  does support the LBT detection and recovery procedure, the UE  205  does not increment the SR transmission counter if the SR is not transmitted due to an LBT failure. 
     As depicted, the procedure  800  begins as the UE  205  detects that an SR was not transmitted due to LBT failure (see block  805 ). The UE  205  determines whether it supports (i.e., has the capability for) LBT detection and recovery (see decision block  810 ). If yes, then the UE  205  does not increment the SR transmission counter (e.g., SR_COUNTER) when the SR is not transmitted due to LBT failure (see block  815 ). Otherwise, if the UE  205  does not support LBT detection and recovery (i.e., also referred to as consistent LBT failure recovery procedure), then the UE  205  increments the SR transmission counter when the SR is not transmitted due to LBT failure (see block  820 ). 
       FIG.  9    depicts a procedure  900  for SR transmission counter handling in case of LBT failure, according to embodiments of a fifth solution. The procedure  900  is performed by a UE operating in a mobile communication network, such as the UE  205 . According to the fifth solution, the UE behavior with respect to SR_COUNTER handling depends on whether the UE  205  has been configured with the consistent LBT failure recovery procedure, i.e., if lbt-FailureRecoveryConfig is configured. 
     For cases where the MAC entity is not configured by RRC with a consistent LBT failure recovery procedure, the UE  205  increments the SR transmission counter (e.g., SR_COUNTER) if the SR (e.g., on PUCCH) is not transmitted due to LBT failure, i.e., an LBT failure is indicated by PHY for the SR transmission. 
     For cases where the UE/MAC is configured by network with the consistent LBT failure recovery procedure, the UE  205  does not increment the SR_COUNTER if the SR is not transmitted due to LBT failure. 
     As depicted, the procedure  900  begins as the UE  205  detects that SR was not transmitted due to LBT failure (see block  905 ). The UE  205  determines whether the MAC entity is configured with consistent LBT failure recovery procedure (see decision block  910 ). If the MAC entity is configured with consistent LBT failure recovery procedure (e.g., parameter lbt-FailureRecoveryConfig is configured), then the UE  205  does not increment the SR transmission counter (e.g., SR_COUNTER) when the SR is not transmitted due to LBT failure (see block  915 ). Otherwise, if the MAC entity is not configured with consistent LBT failure recovery procedure, then the UE  205  increments the SR transmission counter when the SR is not transmitted due to LBT failure (see block  920 ). 
       FIG.  10    depicts a procedure  1000  for SR transmission counter handling in case of LBT failure, according to embodiments of the sixth solution. The procedure  1000  is performed by a UE operating in a mobile communication network, such as the UE  205 . According to a fourth solution, the UE behavior with respect to SR_COUNTER handling does not depend only on the UE capability, but also depends on whether the UE  205  has been configured with the consistent LBT failure recovery procedure, i.e., if lbt-FailureRecoveryConfig is configured. 
     For cases where the UE  205  does not support the LBT detection and recovery functionality, i.e., also referred to as consistent LBT failure recovery procedure, or where the MAC entity is not configured by RRC with a consistent LBT failure recovery procedure, the UE  205  increments the SR transmission counter (e.g., SR_COUNTER) if the SR (e.g., on PUCCH) is not transmitted due to LBT failure, i.e., an LBT failure is indicated by PHY for the SR transmission. 
     For cases where the UE  205  does support the consistent LBT failure recovery procedure and where the UE/MAC is configured by network with the consistent LBT failure recovery procedure, the UE  205  does not increment the SR_COUNTER if the SR is not transmitted due to LBT failure. 
     As depicted, the procedure  1000  begins as the UE  205  detects that SR was not transmitted due to LBT failure (see block  1005 ). The UE  205  determines whether it supports (i.e., has the capability for) LBT detection and recovery (see decision block  1010 ). If yes, then the UE  205  determines whether the MAC entity is configured with consistent LBT failure recovery procedure (see decision block  1015 ). If both the UE  205  supports LBT detection and recovery (i.e., also referred to as consistent LBT failure recovery procedure) and the MAC entity is configured with consistent LBT failure recovery procedure (e.g., parameter lbt-FailureRecoveryConfig is configured), then the UE  205  does not increment the SR transmission counter (e.g., SR_COUNTER) when the SR is not transmitted due to LBT failure (see block  1020 ). Otherwise, if the UE  205  does not support LBT detection and recovery—or if the MAC entity is not configured with consistent LBT failure recovery procedure, then the UE  205  increments the SR transmission counter when the SR is not transmitted due to LBT failure (see block  1025 ). 
     According to a seventh solution, the PHY layer  220  of the UE  205  indicates an LBT success to the MAC layer  225  for cases when the consistent LBT failure recovery procedure is not used by the UE  205 . As noted above, the UE  205  may not use the consistent LBT failure recovery procedure due to UE capability (i.e., where the UE  205  does not support LBT detection and recovery functionality) and/or due to the network not configuring the consistent LBT failure recovery functionality (i.e., no lbt-FailureRecoveryConfig configured). 
     In some embodiments, the PI-TY layer  220  indicates LBT success even for cases when the PRACH transmission cannot be performed due to LBT failure. In some embodiments, the PHY layer  220  indicates LBT success even for cases when the SR transmission cannot be performed due to LBT failure. 
       FIG.  11    depicts a user equipment apparatus  1100  that may be used for counter handling in case of LBT failure, according to embodiments of the disclosure. In various embodiments, the user equipment apparatus  1100  is used to implement one or more of the solutions described above. The user equipment apparatus  1100  may be one embodiment of the remote unit  105  and/or the UE  205 , described above. Furthermore, the user equipment apparatus  1100  may include a processor  1105 , a memory  1110 , an input device  1115 , an output device  1120 , and a transceiver  1125 . 
     In some embodiments, the input device  1115  and the output device  1120  are combined into a single device, such as a touchscreen. In certain embodiments, the user equipment apparatus  1100  may not include any input device  1115  and/or output device  1120 . In various embodiments, the user equipment apparatus  1100  may include one or more of: the processor  1105 , the memory  1110 , and the transceiver  1125 , and may not include the input device  1115  and/or the output device  1120 . 
     As depicted, the transceiver  1125  includes at least one transmitter  1130  and at least one receiver  1135 . In some embodiments, the transceiver  1125  communicates with one or more cells (or wireless coverage areas) supported by one or more base units  121 . In various embodiments, the transceiver  1125  is operable on unlicensed spectrum. Moreover, the transceiver  1125  may include multiple UE panels supporting one or more beams. Additionally, the transceiver  1125  may support at least one network interface  1140  and/or application interface  1145 . The application interface(s)  1145  may support one or more APIs. The network interface(s)  1140  may support 3GPP reference points, such as Uu, N1, PC5, etc. Other network interfaces  1140  may be supported, as understood by one of ordinary skill in the art. 
     The processor  1105 , in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor  1105  may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor  1105  executes instructions stored in the memory  1110  to perform the methods and routines described herein. The processor  1105  is communicatively coupled to the memory  1110 , the input device  1115 , the output device  1120 , and the transceiver  1125 . 
     In various embodiments, the processor  1105  controls the user equipment apparatus  1100  to implement the above described UE behaviors. In certain embodiments, the processor  1105  may include an application processor (also known as “main processor”) which manages application-domain and operating system (“OS”) functions and a baseband processor (also known as “baseband radio processor”) which manages radio functions. 
     In various embodiments, the processor  1105  controls the user equipment apparatus  1100  to implement the above described UE behaviors. For example, the processor  1105  performs a Listen-Before-Talk (“LBT”) procedure for a transmission and detects LBT failure for the transmission. 
     In some embodiments, the processor  1105  determines whether a medium access control (“MAC”) entity of the user equipment apparatus  1100  is configured with a consistent LBT failure recovery procedure. If the MAC entity is not configured with the consistent LBT failure recovery procedure, the processor  1105  increments a transmission counter without transmission of an uplink transmission in response to an indication of the LBT failure. 
     However, if the MAC entity is configured with the consistent LBT failure recovery procedure, then the processor  1105  prevents incrementation of the transmission counter without transmission of an uplink transmission in response to the indication of the LBT failure. In some embodiments, wherein the UE comprises a physical layer. In such embodiments, detecting LBT failure for the transmission may include the physical layer sending a LBT failure indication to the MAC entity. 
     In some embodiments, the processor  1105  determines whether consistent LBT failure recovery functionality is supported at the user equipment apparatus  1100 . If the UE does not support the consistent LBT failure recovery functionality, then the processor  1105  increments a preamble transmission counter without transmission of an uplink transmission in response to the indication of the LBT failure. However, if the user equipment apparatus  1100  supports the consistent LBT failure recovery functionality and the AMC entity is configured with the consistent LBT failure recovery procedure, then the processor  1105  prevents incrementation of the transmission counter without transmission of an uplink transmission in response to the LBT failure. 
     In certain embodiments, the transmission may be a RACH preamble transmission. In such embodiments, the transmission counter may be a preamble transmission counter. In certain embodiments, the transmission may be a SR transmission. In such embodiments, the transmission counter may be a SR transmission counter. 
     In some embodiments, the processor  1105  determines whether consistent LBT failure recovery functionality is supported at the user equipment apparatus  1100 . If the user equipment apparatus  1100  does not support consistent LBT failure recovery functionality, the processor  1105  indicates an LBT success by to a MAC entity of the user equipment apparatus  1100  without performing a corresponding uplink transmission in response to the LBT failure. 
     In some embodiments, determining that consistent LBT failure recovery functionality is not supported occurs in response to the MAC entity not being configured with a consistent LBT failure recovery procedure. In certain embodiments, the transmission may be a RACH preamble transmission. In other embodiments, the transmission may be a SR transmission. 
     The memory  1110 , in one embodiment, is a computer readable storage medium. In some embodiments, the memory  1110  includes volatile computer storage media. For example, the memory  1110  may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory  1110  includes non-volatile computer storage media. For example, the memory  1110  may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory  1110  includes both volatile and non-volatile computer storage media. 
     In some embodiments, the memory  1110  stores data related to counter handling in case of LBT failure. For example, the memory  1110  may store various parameters, panel/beam configurations, resource assignments, policies, and the like as described above. In certain embodiments, the memory  1110  also stores program code and related data, such as an operating system or other controller algorithms operating on the apparatus  1100 . 
     The input device  1115 , in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device  1115  may be integrated with the output device  1120 , for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device  1115  includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device  1115  includes two or more different devices, such as a keyboard and a touch panel. 
     The output device  1120 , in one embodiment, is designed to output visual, audible, and/or haptic signals. In some embodiments, the output device  1120  includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device  1120  may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the output device  1120  may include a wearable display separate from, but communicatively coupled to, the rest of the user equipment apparatus  1100 , such as a smart watch, smart glasses, a heads-up display, or the like. Further, the output device  1120  may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like. 
     In certain embodiments, the output device  1120  includes one or more speakers for producing sound. For example, the output device  1120  may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device  1120  includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the output device  1120  may be integrated with the input device  1115 . For example, the input device  1115  and output device  1120  may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device  1120  may be located near the input device  1115 . 
     The transceiver  1125  communicates with one or more network functions of a mobile communication network via one or more access networks. The transceiver  1125  operates under the control of the processor  1105  to transmit messages, data, and other signals and also to receive messages, data, and other signals. For example, the processor  1105  may selectively activate the transceiver  1125  (or portions thereof) at particular times in order to send and receive messages. 
     The transceiver  1125  includes at least transmitter  1130  and at least one receiver  1135 . One or more transmitters  1130  may be used to provide UL communication signals to a base unit  121 , such as the UL transmissions described herein. Similarly, one or more receivers  1135  may be used to receive DL communication signals from the base unit  121 , as described herein. Although only one transmitter  1130  and one receiver  1135  are illustrated, the user equipment apparatus  1100  may have any suitable number of transmitters  1130  and receivers  1135 . Further, the transmitter(s)  1130  and the receiver(s)  1135  may be any suitable type of transmitters and receivers. In one embodiment, the transceiver  1125  includes a first transmitter/receiver pair used to communicate with a mobile communication network over licensed radio spectrum and a second transmitter/receiver pair used to communicate with a mobile communication network over unlicensed radio spectrum. 
     In certain embodiments, the first transmitter/receiver pair used to communicate with a mobile communication network over licensed radio spectrum and the second transmitter/receiver pair used to communicate with a mobile communication network over unlicensed radio spectrum may be combined into a single transceiver unit, for example a single chip performing functions for use with both licensed and unlicensed radio spectrum. In some embodiments, the first transmitter/receiver pair and the second transmitter/receiver pair may share one or more hardware components. For example, certain transceivers  1125 , transmitters  1130 , and receivers  1135  may be implemented as physically separate components that access a shared hardware resource and/or software resource, such as for example, the network interface  1140 . 
     In various embodiments, one or more transmitters  1130  and/or one or more receivers  1135  may be implemented and/or integrated into a single hardware component, such as a multi-transceiver chip, a system-on-a-chip, an ASIC, or other type of hardware component. In certain embodiments, one or more transmitters  1130  and/or one or more receivers  1135  may be implemented and/or integrated into a multi-chip module. In some embodiments, other components such as the network interface  1140  or other hardware components/circuits may be integrated with any number of transmitters  1130  and/or receivers  1135  into a single chip. In such embodiment, the transmitters  1130  and receivers  1135  may be logically configured as a transceiver  1125  that uses one more common control signals or as modular transmitters  1130  and receivers  1135  implemented in the same hardware chip or in a multi-chip module. 
       FIG.  12    depicts a network apparatus  1200  that may be used for counter handling in case of LBT failure, according to embodiments of the disclosure. In one embodiment, network apparatus  1200  may be one implementation of a RAN node, such as the base unit  121 , the RAN node  212 , or a gNB, as described above. Furthermore, the base network apparatus  1200  may include a processor  1205 , a memory  1210 , an input device  1215 , an output device  1220 , and a transceiver  1225 . 
     In some embodiments, the input device  1215  and the output device  1220  are combined into a single device, such as a touchscreen. In certain embodiments, the network apparatus  1200  may not include any input device  1215  and/or output device  1220 . In various embodiments, the network apparatus  1200  may include one or more of: the processor  1205 , the memory  1210 , and the transceiver  1225 , and may not include the input device  1215  and/or the output device  1220 . 
     As depicted, the transceiver  1225  includes at least one transmitter  1230  and at least one receiver  1235 . Here, the transceiver  1225  communicates with one or more remote units  125 . Additionally, the transceiver  1225  may support at least one network interface  1240  and/or application interface  1245 . The application interface(s)  1245  may support one or more APIs. The network interface(s)  1240  may support 3GPP reference points, such as Uu, N1, N2 and N3. Other network interfaces  1240  may be supported, as understood by one of ordinary skill in the art. 
     The processor  1205 , in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor  1205  may be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or similar programmable controller. In some embodiments, the processor  1205  executes instructions stored in the memory  1210  to perform the methods and routines described herein. The processor  1205  is communicatively coupled to the memory  1210 , the input device  1215 , the output device  1220 , and the transceiver  1225 . 
     In various embodiments, the network apparatus  1200  is a RAN node (e.g., gNB) that communicates with one or more UEs, as described herein. In such embodiments, the processor  1205  controls the network apparatus  1200  to perform the above described RAN behaviors. When operating as a RAN node, the processor  1205  may include an application processor (also known as “main processor”) which manages application-domain and operating system (“OS”) functions and a baseband processor (also known as “baseband radio processor”) which manages radio functions. 
     The memory  1210 , in one embodiment, is a computer readable storage medium. In some embodiments, the memory  1210  includes volatile computer storage media. For example, the memory  1210  may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory  1210  includes non-volatile computer storage media. For example, the memory  1210  may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory  1210  includes both volatile and non-volatile computer storage media. 
     In some embodiments, the memory  1210  stores data related to counter handling in case of LBT failure. For example, the memory  1210  may store parameters, configurations, resource assignments, policies, and the like, as described above. In certain embodiments, the memory  1210  also stores program code and related data, such as an operating system or other controller algorithms operating on the apparatus  1200 . 
     The input device  1215 , in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device  1215  may be integrated with the output device  1220 , for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device  1215  includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device  1215  includes two or more different devices, such as a keyboard and a touch panel. 
     The output device  1220 , in one embodiment, is designed to output visual, audible, and/or haptic signals. In some embodiments, the output device  1220  includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device  1220  may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the output device  1220  may include a wearable display separate from, but communicatively coupled to, the rest of the network apparatus  1200 , such as a smart watch, smart glasses, a heads-up display, or the like. Further, the output device  1220  may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like. 
     In certain embodiments, the output device  1220  includes one or more speakers for producing sound. For example, the output device  1220  may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device  1220  includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the output device  1220  may be integrated with the input device  1215 . For example, the input device  1215  and output device  1220  may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device  1220  may be located near the input device  1215 . 
     The transceiver  1225  includes at least transmitter  1230  and at least one receiver  1235 . One or more transmitters  1230  may be used to communicate with the UE, as described herein. Similarly, one or more receivers  1235  may be used to communicate with network functions in the PLMN and/or RAN, as described herein. Although only one transmitter  1230  and one receiver  1235  are illustrated, the network apparatus  1200  may have any suitable number of transmitters  1230  and receivers  1235 . Further, the transmitter(s)  1230  and the receiver(s)  1235  may be any suitable type of transmitters and receivers. 
     The transceiver  1225  is operable on unlicensed spectrum, wherein the transceiver  1225  includes a plurality of gNB panels. As used herein, a “gNB panel” refers to a logical entity that may be mapped to physical gNB antennas. Depending on the implementation, a “gNB panel” can have an operational role of Unit of antenna group to control its Tx beam independently. 
       FIG.  13    depicts one embodiment of a method  1300  for counter handling in case of LBT failure, according to embodiments of the disclosure. In various embodiments, the method  1300  is performed by a user equipment device in a mobile communication network, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1100 , described above. In some embodiments, the method  1300  is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  1300  begins and performs  1305  a LBT procedure for a transmission. The method  1300  includes detecting  1310  LBT failure for the transmission. The method  1300  includes determining  1315  whether a MAC entity of the UE is configured with a consistent LBT failure recovery procedure. If the MAC entity of the UE is not configured with the consistent LBT failure recovery procedure, the first method includes incrementing  1320  a transmission counter without transmission of an uplink transmission in response to an indication of the LBT failure. The method  1300  ends. 
       FIG.  14    depicts one embodiment of a method  1400  for counter handling in case of LBT failure, according to embodiments of the disclosure. In various embodiments, the method  1400  is performed by a user equipment device in a mobile communication network, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1100 , described above. In some embodiments, the method  1400  is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  1400  begins and performs  1405  a LBT procedure for a transmission. The method  1400  includes detecting  1410  LBT failure for the transmission. The method  1400  includes determining  1415  whether consistent LBT failure recovery functionality is supported at the UE. If the UE does not support consistent LBT failure recovery functionality, the method  1400  includes indicating  1420  an LBT success by to a MAC entity of the UE without performing a corresponding uplink transmission in response to the LBT failure. The method  1400  ends. 
     Disclosed herein is a first apparatus for counter handling in case of LBT failure, according to embodiments of the disclosure. The first apparatus may be implemented by a user equipment device in a mobile communication network, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1100 , described above. The first apparatus includes a processor and a transceiver for operation with shared spectrum channel access. The processor performs a Listen-Before-Talk (“LBT”) procedure for a transmission and detects LBT failure for the transmission. The processor determines whether a medium access control (“MAC”) entity of the UE is configured with a consistent LBT failure recovery procedure. If the MAC entity is not configured with the consistent LBT failure recovery procedure, the processor increments a transmission counter without transmission of an uplink transmission in response to an indication of the LBT failure. 
     However, if the MAC entity is configured with the consistent LBT failure recovery procedure, then the processor prevents incrementation of the transmission counter without transmission of an uplink transmission in response to the indication of the LBT failure. In some embodiments, wherein the UE comprises a physical layer. In such embodiments, detecting LBT failure for the transmission may include the physical layer sending a LBT failure indication to the MAC entity. 
     In some embodiments, the processor determines whether consistent LBT failure recovery functionality is supported at the UE. If the UE does not support the consistent LBT failure recovery functionality, then the processor increments a preamble transmission counter without transmission of an uplink transmission in response to the indication of the LBT failure. However, if the UE supports the consistent LBT failure recovery functionality and the AMC entity is configured with the consistent LBT failure recovery procedure, then the processor prevents incrementation of the transmission counter without transmission of an uplink transmission in response to the LBT failure. 
     In certain embodiments, the transmission may be a RACH preamble transmission. In such embodiments, the transmission counter may be a preamble transmission counter. In certain embodiments, the transmission may be a SR transmission. In such embodiments, the transmission counter may be a SR transmission counter. 
     Disclosed herein is a first method for counter handling in case of LBT failure, according to embodiments of the disclosure. The first method may be performed by a user equipment device in a mobile communication network, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1100 . The first method includes performing a LBT procedure for a transmission and detecting LBT failure for the transmission. The first method includes determining whether a MAC entity of the UE is configured with a consistent LBT failure recovery procedure. If the MAC entity of the UE is not configured with the consistent LBT failure recovery procedure, the first method includes incrementing a transmission counter without transmission of an uplink transmission in response to an indication of the LBT failure. 
     However, if the MAC entity of the UE is configured with the consistent LBT failure recovery procedure, then the first method includes preventing incrementation of the transmission counter without transmission of an uplink transmission in response to the indication of the LBT failure. In some embodiments, the UE comprises a physical layer. In such embodiments, detecting LBT failure for the transmission may include the physical layer sending a LBT failure indication to the MAC entity. 
     In some embodiments, the first method includes determining whether consistent LBT failure recovery functionality is supported at the UE. If the UE does not support the consistent LBT failure recovery functionality, then the first method includes incrementing a preamble transmission counter without transmission of an uplink transmission in response to the indication of the LBT failure. However, if the UE supports the consistent LBT failure recovery functionality and if the MAC entity is configured with the consistent LBT failure recovery procedure, then the first method includes preventing incrementation of the transmission counter without transmission of an uplink transmission in response to the LBT failure. 
     In certain embodiments, the transmission may be a RACH preamble transmission. In such embodiments, the transmission counter may be a preamble transmission counter. In certain embodiments, the transmission may be a SR transmission. In such embodiments, the transmission counter may be a SR transmission counter. 
     Disclosed herein is a second apparatus for counter handling in case of LBT failure, according to embodiments of the disclosure. The second apparatus may be implemented by a user equipment device in a mobile communication network, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1100 , described above. The second apparatus includes a processor and a transceiver for operation with shared spectrum channel access. The processor performs a LBT procedure for a transmission (e.g., on shared spectrum) and detects LBT failure for the transmission opportunity. The processor determines whether consistent LBT failure recovery functionality is supported at the UE. If the UE does not support consistent LBT failure recovery functionality, the processor indicates an LBT success by to a MAC entity of the UE without performing a corresponding uplink transmission in response to the LBT failure. 
     In some embodiments, determining that consistent LBT failure recovery functionality is not supported occurs in response to the MAC entity not being configured with a consistent LBT failure recovery procedure. In certain embodiments, the transmission may be a RACH preamble transmission. In other embodiments, the transmission may be a SR transmission. 
     Disclosed herein is a second method for counter handling in case of LBT failure, according to embodiments of the disclosure. The second method may be performed by a user equipment device in a mobile communication network, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  1100 . The second method includes performing a LBT procedure for a transmission and detecting LBT failure for the transmission. The second method includes determining whether consistent LBT failure recovery functionality is supported at the UE. If the UE does not support consistent LBT failure recovery functionality, the second method includes indicating an LBT success by to a MAC entity of the UE without performing a corresponding uplink transmission in response to the LBT failure. 
     In some embodiments, determining that consistent LBT failure recovery functionality is not supported occurs in response to the MAC entity not being configured with a consistent LBT failure recovery procedure. In certain embodiments, the transmission may be a RACH preamble transmission. In other embodiments, the transmission may be a SR transmission. 
     Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.