WTRU and execution method thereof

Abstract

The invention provides a wireless transmit / receive unit (WTRU) and an execution method thereof. The WTRU may be configured to perform radio link monitoring (RLM) based on an RLM reference signal (RLM-RS) transmitted in a cell operating in an unlicensed spectrum. The WTRU may evaluate a radio link failure (RLF) state of the cell based on the RLM-RS using a first RLM standard. For example, due to a Listen Before Talk (LBT) failure at a g Node B (gNB), a transmission instance of the RLM-RS may be skipped. The WTRU may adapt or change the first RLM standard and / or evaluate the RLF state of the cell operating in the unlicensed spectrum using a second RLM standard based on determining that a transmission instance of the RLM-RS is skipped. The first RLM criterion may correspond to a first RLM process utilizing a first set of RLM parameters. The second RLM criterion may correspond to a second RLM process utilizing a second set of RLM parameters.

Description

This application is a divisional application of Chinese patent application No. 201980052354.1, whose application date is June 18, 2019 and entitled “WTRU and its implementation method”. The contents of the parent application are incorporated herein by reference in their entirety. Cross reference to related cases

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 686,758, filed on June 19, 2018, U.S. Provisional Patent Application No. 62 / 715,641, filed on August 7, 2018, and U.S. Provisional Patent Application No. 62 / 790,183, filed on January 9, 2019, the contents of which are incorporated herein by reference in their entirety. Background Art

[0002] Mobile communications using wireless communications continue to develop. The fifth generation may be referred to as 5G. Previous (legacy) generations of mobile communications may be, for example, fourth generation (4G) Long Term Evolution (LTE). Summary of the invention

[0003] Systems, methods, and means for radio link monitoring in a shared spectrum are disclosed herein. A wireless transmit-receive unit may be configured to determine a channel state. For example, a channel state may correspond to a relative state of a channel, such as idle (e.g., high quality, low usage, etc.), busy (e.g., frequently used, good or poor quality when available, etc.), poor / bad (e.g., low quality even when channel usage is low), etc. One or more of the above.

[0004] A wireless transmit / receive unit (WTRU) may be configured to utilize techniques to determine or otherwise distinguish between a bad channel (e.g., poor channel conditions) and a busy channel (e.g., high utilization and / or interference levels in a channel with otherwise acceptable channel conditions). The WTRU may evaluate the channel and, when processing measurement samples, identify a level of uncertainty and / or ambiguity as to whether the measurement corresponds to a bad channel, a poor channel, and / or both.

[0005] A WTRU may be configured to perform radio link monitoring (RLM) measurements in a cell. The cell may transmit a radio link monitoring reference signal (RLM-RS) in an unlicensed spectrum. The WTRU may be configured to perform RLM measurements based on the RLM-RS. The WTRU may measure the RLM-RS. The WTRU may evaluate a radio link failure (RLF) state of a cell using a first RLM criterion based on determining that a transmission instance of the RLM-RS is transmitted in the cell. For example, the WTRU may evaluate the RLF state of the cell using a first RLM criterion based on measuring the RLM-RS. For example, the transmission instance of the RLM-RS may be skipped due to a listen-before-talk (LBT) failure of a gNodeB (gNB). The WTRU may determine that the transmission instance of the RLM-RS is skipped. The WTRU may adapt or change the first RLM criterion and / or use a second RLM criterion to evaluate the RLF state of the cell operating in the unlicensed spectrum based on determining that the transmission instance of the RLM-RS is skipped. The first RLM standard may correspond to a first RLM procedure utilizing a first set of RLM parameters.The second RLM standard may correspond to a second RLM procedure utilizing a second set of RLM parameters.

[0006] The WTRU may be instructed or determine that the transmission instance of the RLM-RS is skipped. For example, the WTRU may be configured to receive an indication from the gNB indicating that the transmission instance of the RLM-RS is skipped.

[0007] The WTRU may be configured to determine that the transmission instance of the RLM-RS is skipped based on one or more detected or implicit criteria. For example, the WTRU may not be able to detect a characteristic associated with the RLM-RS during the transmission instance. The WTRU may determine that the transmission instance of the RLM-RS is skipped based on failure to detect a characteristic associated with the RLM-RS during the transmission instance. The characteristic may include one or more of a scrambling identity (ID) and / or a cyclic shift associated with the RLM-RS. The WTRU may be configured to measure a received signal strength indicator (RSSI) of a resource of the cell. The WTRU may determine that the measured RSSI is greater than a threshold. The WTRU may be configured to determine that the transmission instance of the RLM-RS is skipped based on determining that the measured RSSI is greater than the threshold. The WTRU may be configured to measure power on one or more resource elements blanked by the gNB. The WTRU may determine that the measured power is above a threshold. The WTRU may be configured to determine that the transmission instance of the RLM-RS is skipped based on determining that the measured power is above the threshold. The WTRU may be configured to determine that the transmission instance of the RLM-RS is skipped based on a condition or a combination of conditions. For example, the WTRU may be configured to determine that the transmission instance of the RLM-RS is skipped when the RSSI in the resource elements associated with the RLM-RS is above a first threshold and the RSRP of the resource elements associated with the RLM-RS is below a second threshold.

[0008] The first RLM standard and the second RLM standard may be different. The second RLM standard may include, for example, the use of a no-sync (NS) indication when it is determined (e.g., by a WTRU) that an RLM-RS is not received. The second RLM standard may include a counter for no-sync (NS) indications. The second RLM standard may include a fractional counter for out-of-sync (OOS) indications. The second RLM standard may include a fractional increment of the OOS counter. The first RLM standard and the second RLM standard may include different conditions requiring a number of consecutive OOS indications to declare RLF. For example, the number of consecutive OOS indications required in the second RLM standard may be greater than the first number of consecutive OOS indications required in the first RLM standard.

[0009] The second RLM criterion may include a calculation of a block error rate (BLER). For example, the WTRU may be configured to calculate the BLER by applying a negative offset increment to the BLER for an indication interval. The WTRU may be configured to compare the calculated BLER with a threshold. The WTRU may be configured to generate at least one of an OOS indication, a synchronization (IS) indication, or a NS indication based on the comparison.

[0010] The WTRU may be configured to perform LBT in a cell in an unlicensed spectrum. The WTRU may defer a plurality of uplink (UL) transmissions. The WTRU may determine that the number of deferred UL transmissions exceeds a threshold. The WTRU may send an indication of RLF based on determining that the number of deferred UL transmissions exceeds the threshold. The WTRU may determine that a UL access delay exceeds a threshold. The WTRU may send an indication of RLF based on determining that the UL access delay exceeds the threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented.

[0012] Figure 1B is a diagram showing that according to an embodiment, Figure 1A A system diagram of an exemplary wireless transmit / receive unit (WTRU) for use within a communication system is shown.

[0013] Figure 1C is a diagram showing that according to an embodiment, Figure 1A A system diagram of an exemplary radio access network (RAN) and an exemplary core network (CN) used within a communication system is shown.

[0014] Figure 1D is a diagram showing that according to an embodiment, Figure 1A A system diagram of another exemplary RAN and another exemplary CN used within the communication system shown.

[0015] Figure 2 An example of a WTRU using an improved RLM implementation is shown.

[0016] Figure 3 An example flow chart that may be part of an RLM implementation is shown. DETAILED DESCRIPTION

[0017] Figure 1A1 is a schematic diagram of an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources including wireless bandwidth. For example, the communication system 100 may use one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT-spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, and filter bank multi-carrier (FBMC), etc.

[0018] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110, and other networks 112, although it should be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network components. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, any of the WTRUs 102a, 102b, 102c, 102d may be referred to as a “station” and / or “STA”, which may be configured to transmit and / or receive wireless signals, and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices working in an industrial and / or automated process chain environment), consumer electronic devices, and devices working on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, 102d may be interchangeably referred to as a UE.

[0019] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to facilitate access to one or more communication networks (e.g., CN 106 / 115, Internet 110, and / or other networks 112) by wirelessly interfacing with at least one of the WTRUs 102a, 102b, 102c, 102d. For example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, a New Radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. Although each of the base stations 114a, 114b is described as a single component, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network components.

[0020] The base station 114a may be part of the RAN 104 / 113, and the RAN may also include other base stations and / or network components (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, and the like. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies called cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a specific geographic area that is relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., each transceiver corresponds to a sector of the cell. In an embodiment, the base station 114a may use multiple-input multiple-output (MIMO) technology, and may use multiple transceivers for each sector of the cell. For example, by using beamforming, signals may be transmitted and / or received in a desired spatial direction.

[0021] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0022] More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, among others. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish an air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0023] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0024] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology that may establish the air interface 116 using new radio (NR), such as NR radio access.

[0025] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE radio access and NR radio access (e.g., using dual connectivity (DC) principles). Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0026] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), and GSM EDGE (GERAN), among others.

[0027] Figure 1A The base station 114b in the example may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may use any appropriate RAT to facilitate wireless connectivity in a local area, such as a business location, a residence, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may establish a wireless local area network (WLAN) by implementing a radio technology such as IEEE 802.11. In an embodiment, the base station 114b and the WTRUs 102c, 102d may establish a wireless personal area network (WPAN) by implementing a radio technology such as IEEE 802.15. In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell by using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, and the like). As Figure 1A As shown, the base station 114b may be directly connected to the Internet 110. Thus, the base station 114b does not need to access the Internet 110 via the CN 106 / 115.

[0028] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calls, Internet connectivity, video distribution, etc., and / or may perform advanced security functions such as user authentication. Although in Figure 1AAlthough not shown, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT or a different RAT as the RAN 104 / 113. For example, in addition to being connected to the RAN 104 / 113 employing NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0029] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer network devices that use common communication protocols (e.g., TCP, User Datagram Protocol (UDP), and / or IP in the Transmission Control Protocol / Internet Protocol (TCP / IP) Internet protocol suite). The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, where the one or more RANs may use the same RAT or a different RAT as the RAN 104 / 113.

[0030] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0031] Figure 1B is a system diagram illustrating an exemplary WTRU 102. Figure 1B As shown, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a numeric keypad 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or peripherals 138. It should be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0032] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, however it should be appreciated that the processor 118 and the transceiver 120 may also be integrated together in one electronic component or chip.

[0033] The transmit / receive component 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive component 122 may be an antenna configured to transmit and / or receive RF signals. As an example, in another embodiment, the transmit / receive component 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, the transmit / receive component 122 may be configured to transmit and / or receive RF and light signals. It should be appreciated that the transmit / receive component 122 may be configured to transmit and / or receive any combination of wireless signals.

[0034] Although in Figure 1B 102 as a single component, but the WTRU 102 may include any number of transmit / receive components 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive components 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0035] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive component 122 and to demodulate signals received by the transmit / receive component 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers that allow the WTRU 102 to communicate via multiple RATs (e.g., NR and IEEE 802.11).

[0036] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a numeric keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may receive user input data from these components. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store information in any suitable memory such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0037] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power for use by other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (Ni-Cd), nickel-zinc (Ni-Zn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0038] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) related to the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It should be appreciated that the WTRU 102 may acquire location information via any suitable positioning method while remaining consistent with an embodiment.

[0039] The processor 118 may also be coupled to other peripheral devices 138, wherein the peripheral devices may include one or more software and / or hardware modules that provide additional features, functions, and / or wired or wireless connectivity. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Modules, frequency modulation (FM) radio units, digital music players, media players, video game console modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices, and activity trackers, etc. The peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors, geographic location sensors, altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors, etc.

[0040] The WTRU 102 may include a full-duplex radio in which the reception or transmission of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous for the radio. A full-duplex radio may include an interference management unit that reduces and / or substantially eliminates self-interference by means of hardware (e.g., chokes) or by signal processing by a processor (e.g., a separate processor (not shown) or by the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio that transmits and receives some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)).

[0041] Figure 1C 1 is a system diagram showing the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c using an E-UTRA radio technology over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0042] The RAN 104 may include eNode-Bs 160a, 160b, 160c, however it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0043] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0044] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the aforementioned components is described as being part of the CN 106, it should be appreciated that any of these components may be owned and / or operated by an entity other than the CN operator.

[0045] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, performing bearer activation / deactivation processing, selecting a particular serving gateway during an initial attach procedure for the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0046] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may also perform other functions, such as anchoring the user plane during an inter-eNB handover, triggering paging processing when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the contexts of the WTRUs 102a, 102b, 102c, and the like.

[0047] The SGW 164 may be connected to the PGW 146, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0048] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include or communicate with an IP gateway, such as an IP Multimedia Subsystem (IMS) server, and the IP gateway may serve as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0049] Although in Figures 1A-1D While the WTRU is described as a wireless terminal, it should be appreciated that in certain representative embodiments, such a terminal may use a (eg, temporary or permanent) wired communication interface with a communication network.

[0050] In a representative embodiment, the other network 112 may be a WLAN.

[0051] A WLAN using an infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may access or be connected to a distributed system (DS) or other types of wired / wireless networks that send traffic into and / or out of the BSS. Traffic originating from outside the BSS and destined for the STA may arrive through the AP and be delivered to the STA. Traffic originating from the STA and destined for a destination outside the BSS may be sent to the AP for delivery to the corresponding destination. Traffic between STAs within the BSS may be sent through the AP, for example, under the condition that the source STA may send traffic to the AP and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. The point-to-point traffic may be sent using a direct link establishment (DLS) between the source and destination STAs (e.g., directly therebetween). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z channelized DLS (TDLS)). For example, a WLAN using an independent BSS (IBSS) mode does not have an AP, and STAs (e.g., all STAs) within or using the IBSS can communicate directly with each other. Here, the IBSS communication mode may sometimes be referred to as an "ad-hoc" communication mode.

[0052] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, the AP may transmit a beacon on a fixed channel (e.g., a primary channel). The primary channel may have a fixed width (e.g., a bandwidth of 20 MHz) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access (CSMA / CA) with collision avoidance (e.g., in an 802.11 system) may be implemented. For CSMA / CA, STAs (e.g., each STA) including the AP may sense the primary channel. If a particular STA senses / detects and / or determines that the primary channel is busy, the particular STA may back off. In a specified BSS, one STA (e.g., only one station) transmits at any given time.

[0053] A high throughput (HT) STA may communicate using a 40 MHz wide channel (eg, by combining a 20 MHz wide primary channel with a 20 MHz wide adjacent or non-adjacent channel to form a 40 MHz wide channel).

[0054] Very high throughput (VHT) STA can support channels with widths of 20MHz, 40MHz, 80MHz and / or 160MHz. 40MHz and / or 80MHz channels can be formed by combining continuous 20MHz channels. A 160MHz channel can be formed by combining 8 continuous 20MHz channels or by combining two discontinuous 80MHz channels (this combination can be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data can be transmitted and passed through a segment parser, which can separate the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing can be performed separately on each stream. The stream can be mapped on two 80MHz channels, and the data can be transmitted by the STA performing the transmission. At the receiver of the STA performing the reception, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the medium access control (MAC).

[0055] 802.11af and 802.11ah support working modes below 1 GHz. Compared with 802.11n and 802.11ac, the channel working bandwidth and carrier used in 802.11af and 802.11ah are reduced. 802.11af supports 5MHz, 10MHz and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support instrument type control / machine type communication, such as MTC devices in macro coverage areas. MTC devices can have certain capabilities, such as limited capabilities including support (e.g., only support) certain and / or limited bandwidths. MTC devices can include a battery, and the battery life of the battery is higher than a threshold (e.g., for maintaining a very long battery life).

[0056] For WLAN systems that can support multiple channels and channel bandwidths (e.g., 802.11n, 802.11ac, 802.11af, and 802.11ah), these systems include channels that can be designated as primary channels. The bandwidth of the primary channel can be equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by a certain STA, where the STA originates from all STAs operating in the BSS that supports the minimum bandwidth operating mode. In the example of 802.11ah, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz and / or other channel bandwidth operating modes, for STAs (e.g., MTC-type devices) that support (e.g., only support) 1MHz mode, the width of the primary channel can be 1MHz. Carrier sensing and / or network allocation vector (NAV) settings can depend on the state of the primary channel. If the primary channel is busy (eg, because a STA (which only supports 1 MHz operating mode) is transmitting to the AP), then the entire available frequency band may be considered busy even though most of the available frequency band remains idle and available for use.

[0057] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. Depending on the country code, the total bandwidth available for 802.11ah is 6MHz to 26MHz.

[0058] Figure 1D 1 is a system diagram showing the RAN 113 and the CN 115 according to an embodiment. As described above, the RAN 113 may communicate with the WTRUs 102a, 102b, 102c using NR radio technology over the air interface 116. The RAN 113 may also communicate with the CN 115.

[0059] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may use beamforming processing to transmit and / or receive signals to and / or from the gNBs 180a, 180b, 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit wireless signals to the WTRU 102a and receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0060] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with a scalable digital configuration. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may be different for different transmissions, different cells, and / or different portions of the radio transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., containing different numbers of OFDM symbols and / or lasting different absolute time lengths).

[0061] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing other RANs (e.g., the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRU 102a, 102b, 102c may communicate / connect to the gNB 180a, 180b, 180c while communicating / connecting to another RAN (e.g., the eNode-B 160a, 160b, 160c). For example, the WTRU 102a, 102b, 102c may communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c in a substantially simultaneous manner by implementing the DC principle. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRU 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput to serve the WTRU 102a, 102b, 102c.

[0062] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support network slicing, dual connectivity, implement interworking between NR and E-UTRA, route user plane data to a user plane function (UPF) 184a, 184b, and route control plane information to an access and mobility management function (AMF) 182a, 182b, and the like. Figure 1D As shown, gNBs 180a, 180b, and 180c can communicate with each other through the Xn interface.

[0063] Figure 1DThe CN 115 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and may include a data network (DN) 185a, 185b. Although each of the aforementioned components is described as part of the CN 115, it should be understood that any of these components may be owned and / or operated by an entity other than the CN operator.

[0064] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, terminating NAS signaling, and mobility management, etc. The AMF 182a, 182b may use network slicing processing to customize the CN support provided to the WTRU 102a, 102b, 102c based on the type of service used by the WTRU 102a, 102b, 102c. As an example, different network slices may be established for different use cases, such as services relying on Ultra Reliable Low Latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, and / or services for machine type communication (MTC) access, etc. The AMF 182 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) using other radio technologies (e.g., LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi).

[0065] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and may configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU or UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0066] The UPF 184a, 184b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which can provide the WTRUs 102a, 102b, 102c with access to packet-switched networks (e.g., the Internet 110) to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b can perform other functions such as routing and forwarding packets, implementing user plane policies, supporting multi-host PDU sessions, processing user plane QoS, buffering downlink packets, and providing mobility anchor processing, etc.

[0067] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the local data network (DN) 185a, 185b via an N3 interface connected to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b and through the UPF 184a, 184b.

[0068] In view of Figures 1A-1D and about Figures 1A-1D In accordance with the corresponding description of the present invention, one or more or all functions described herein in comparison with one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a-d, base station 114a-b, eNodeB 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN185ab and / or one or more other devices described herein. These simulation devices may be one or more devices configured to simulate one or more or all functions described herein. For example, these simulation devices may be used to test other devices and / or simulate network and / or WTRU functions.

[0069] The simulation device can be designed to implement one or more tests about other devices in a laboratory environment and / or an operator network environment. For example, the one or more simulation devices can perform one or more or all functions while being implemented and / or deployed as a part of a wired and / or wireless communication network in whole or in part to test other devices inside the communication network. The one or more simulation devices can perform one or more or all functions while being temporarily implemented or deployed as a part of a wired and / or wireless communication network. The simulation device can be directly coupled to other equipment to perform the test, and / or can use over-the-air wireless communication to perform the test.

[0070] The one or more simulation devices can perform one or more functions, including all functions, while not being implemented or deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test lab and / or a test scenario of a wired and / or wireless communication network that is not deployed (e.g., tested) to implement tests on one or more components. The one or more simulation devices can be test devices. The simulation device can transmit and / or receive data using direct RF coupling and / or wireless communication with the aid of RF circuits (e.g., which can include one or more antennas).

[0071] The term "network" as used herein may refer to one or more gNBs, which may be associated with one or more transmit / receive points (TRPs) or any other nodes in a radio access network. PDU may refer to a protocol data unit.

[0072] The term "shared spectrum" as used herein may refer to any spectrum shared between multiple operators and / or multiple technologies, such as 3GPP, WiFi, radar, satellite, etc. "Shared spectrum" as used herein may include lightly licensed spectrum, licensed spectrum shared between operators, and / or unlicensed spectrum. The terms "shared" and "unlicensed" are used interchangeably herein. Although the techniques described herein may be applicable to shared spectrum scenarios, these techniques may be applicable to non-shared spectrum. Unless specifically noted herein, these examples should not be interpreted as shared spectrum-only deployments.

[0073] The next generation of air interfaces (including further evolution of LTE Advanced Pro and New Radio (NR)) can support a wide range of use cases with different service requirements. For example, low overhead, low data rate, power efficient services (e.g., mMTC), ultra-reliable, low latency services (e.g., URLLC), and / or high data rate mobile broadband services (e.g., eMBB) can be supported. A variety of wireless transmit / receive unit (WTRU) capabilities can be supported. For example, low power, low bandwidth WTRUs, WTRUs capable of having very wide bandwidths (e.g., 80MHz), and / or WTRUs supporting high frequencies (e.g., greater than 6GHz) can be supported. Different spectrum usage models can be supported. For example, stationary / fixed and / or high-speed train scenarios can be supported. An architecture that is flexible enough to accommodate different deployment scenarios can be used. For example, one or more of an architecture that is independent, non-independent (e.g., with assistance from another air interface), centralized, virtualized, and / or distributed in an ideal / non-ideal backhaul can be used.

[0074] A WTRU may operate using a bandwidth part (BWP) in a carrier (e.g., in NR). A WTRU may access a cell using a (e.g., initial) BWP. A WTRU may be configured with a set of BWPs, e.g., to continue operating. For example, a WTRU may have one active BWP at any given moment. A BWP (e.g., each BWP) may be configured with a set of control resource sets (CORESETs). A WTRU may blindly decode a physical downlink control channel (PDCCH) candidate for scheduling within a CORESET.

[0075] NR may support variable transmission duration(s) and / or feedback timing. A physical downlink shared channel (PDSCH) and / or physical uplink shared channel (PUSCH) transmission may occupy a subset of symbols (e.g., a contiguous subset) of a slot. The subset of symbols may be associated with a variable transmission duration(s). Downlink control information (DCI) for DL ​​assignments may include an indication of the timing of feedback for the WTRU (e.g., by pointing to a specific PUCCH resource), such as with variable feedback timing.

[0076] NR may support multiple types of physical uplink control channel (PUCCH) resources. For example, NR may support short PUCCH and long PUCCH. Short PUCCH may be sent using 1 or 2 OFDM symbols. Long PUCCH may be sent using, for example, 14 orthogonal frequency division multiplexing (OFDM) symbols. PUCCH types (e.g., each PUCCH type) may have multiple formats. The format may depend on the type and / or size of the corresponding payload.

[0077] Beamforming can be used to compensate for increased path loss at higher frequencies (eg, greater than 6 GHz).A relatively large number of antenna elements can be used to achieve higher beamforming gain.

[0078] Analog and / or hybrid beamforming may be used to reduce implementation costs (e.g., reduce the number of RF chains). Analog and / or hybrid beamforming may be multiplexed in time. Beamforming may be applied to one or more of synchronization, PBCH, or control channels, e.g., to provide cell-wide coverage. The term "beam scanning" as used herein may refer to the transmission and / or reception of beamformed channels (e.g., which are multiplexed in time and / or frequency and / or space).

[0079] The term "reference signal" as used herein may refer to a signal, preamble, or system signature that may be received and / or transmitted by a WTRU (e.g., for one or more purposes as described herein). Different reference signals may be defined for beam management in the DL and / or UL. For example, downlink beam management may use one or more of a channel state information reference signal (CSI-RS), a demodulation reference signal (DMRS), or a synchronization signal, etc. Uplink beam management may use one or more of a sounding reference signal (SRS), a DMRS, or a random access channel (RACH), etc.

[0080] Operation may occur in a shared spectrum deployment. Operation in an unlicensed band may be subject to limitations on one or more of transmit power control (TPC), radio frequency (RF) output power, or power density (e.g., as given by average effective isotropic radiated power (EIRP) at the highest power level and / or average EIRP density). Operation in an unlicensed band may be affected by requirements on out-of-band emissions of the transmission(s). The requirements may be specific to the frequency band and / or geographic location.

[0081] Operations in unlicensed bands may be subject to nominal channel bandwidth (NCB) and / or occupied channel bandwidth (OCB) requirements. OCBs may be defined for unlicensed spectrum in the 5 GHz region. For example, the NCB may be the widest band including a guard band assigned to a single channel. The NCB may be at least 5 MHz. The OCB may include a bandwidth that contains 99% of the signal power. The OCB may be between 80% and 100% of the declared NCB. For example, during established communications, a device may be allowed to temporarily operate in a mode in which the OCB of the device is reduced. The OCB of the device may be reduced to 40% of the NCB of the device (e.g., a minimum of 4 MHz).

[0082] Channel access in an unlicensed band may use listen-before-talk (LBT). LBT may be enforced (eg, independent of) whether the channel is occupied.

[0083] LBT can be characterized, for example, for a frame-based system. LBT can be characterized by one or more of a clear channel assessment (CCA) time (e.g., ~20 μs), a channel occupancy time (e.g., minimum 1 ms, maximum 10 ms), an idle period (e.g., minimum 5% of the channel occupancy time), a fixed frame period (e.g., equal to the channel occupancy time + idle period), a short control signaling transmission time (e.g., maximum 5% duty cycle within a 50 ms observation period), or a CAA energy detection threshold.

[0084] LBT can be characterized, for example, for a load-based system. In a load-based system, the transmit / receive structure may not be fixed in time. LBT can be characterized by a number N corresponding to the number of idle time slots in an extended CCA (e.g., instead of a fixed frame period). N can be randomly selected within a certain range.

[0085] Deployment scenarios may include different standalone NR-based operations, different variants of dual connectivity operations, and / or different variants of carrier aggregation (CA). Variants of dual connectivity operations may include one or more of the following: EN-DC, where at least one carrier operates in accordance with an LTE radio access technology (RAT); or, NR DC, where at least two sets of one or more carriers operate in accordance with an NR RAT. Variants of CA may include different combinations of zero or more carriers for each of the LTE RAT and the NR RAT.

[0086] Listen before talk (LBT) can be used by a device that applies a clear channel assessment (CCA) check before using a channel. The CCA can utilize energy detection and / or other methods to determine the presence or absence of other signals on the channel, for example, to determine whether the channel is occupied or idle, respectively. The use of LBT in unlicensed bands can be enforced. Carrier sensing (e.g., via LBT) can be a way to fairly share unlicensed spectrum. Carrier sensing (e.g., via LBT) can be considered an important feature for fair and / or friendly operation in unlicensed spectrum in a single global solution framework.

[0087] Discontinuous transmissions may occur on carriers with limited maximum transmission duration. In unlicensed spectrum, channel availability may not be guaranteed. Continuous transmissions may be prohibited. Limits may be imposed on the maximum duration of transmission bursts in unlicensed spectrum. Discontinuous transmissions with limited maximum transmission duration may be a feature for License Assisted Access (LAA).

[0088] Carrier selection may be performed. Carrier selection may be used for LAA nodes to select a carrier (e.g., one that has low interference and enables coexistence with other unlicensed spectrum deployments). There may be a large amount of available bandwidth in unlicensed spectrum.

[0089] TPC may be a requirement by which a transmitting device can reduce transmit power compared to a maximum nominal transmit power (eg, by a ratio of 3dB or 6dB).

[0090] Radio resource management (RRM) measurements (eg, including cell identification) may be performed. RRM measurements (eg, including cell identification) may enable mobility between secondary cells (SCells) and / or robust operation in unlicensed bands.

[0091] CSI measurements (eg, including channel and / or interference) may occur. A WTRU operating in an unlicensed carrier may support frequency / time estimation and / or synchronization, eg, to enable RRM measurements and / or for successful reception of information on the unlicensed band.

[0092] Transmission instances of RLM-RS may be interfered with or skipped. Interfered or skipped transmission instances of RLM-RS may be due to LBT failure (e.g., LBT failure of gNB). Transmission in unlicensed spectrum may be preceded by an LBT period or process (e.g., at the gNB). Performing LBT may enable coexistence with 3GPP and non-3GPP neighbors (e.g., WiFi). RLM (e.g., RLM process) may rely on periodic transmission of reference signals. The reference signal may include, for example, RLM-RS (one or more). When used herein, the term RLM-RS (one or more) may refer to any reference signal used by the WTRU to monitor the radio link status. For example, RLM-RS (one or more) may correspond to one or more synchronization signals; or blocks, one or more CSI-RS and / or other types of reference signals.

[0093] In some communication scenarios (e.g., unlicensed spectrum), periodic transmission of RLM-RS(s) may not be guaranteed. For example, RLM-RS transmissions may be subject to transmission uncertainty because the channel may already be occupied, which may result in failed LBT. For example, when LBT fails (e.g., due to the channel being occupied by another user or another radio access technology), transmission instances of RLM-RS(s) may be skipped. The WTRU may or may not consider the absence of RLM-RS(s) as an out-of-sync (OOS) condition, e.g., depending on its configured mode and / or other observed criteria. As an example, the WTRU may not be able to detect RLM-RS transmissions due to interference from a hidden node.

[0094] The WTRU may determine a temporary interference condition as an OOS condition. During a busy channel, an OOS indication may be triggered. An OOS indication triggered during a busy channel may not indicate channel quality. An OOS indication triggered during a busy channel may result in a transient change in perceived cell coverage (e.g., at the WTRU). The WTRU may trigger a radio link failure (RLF) and / or may reestablish to the same cell. Interruptions, data loss, and / or unnecessary signaling may ensue. A large number of WTRUs on the network may trigger a reconstruction during a busy channel condition, which may result in a signaling storm, for example. RLM may be enhanced to handle RLM-RS transmissions that may be subject to transmission uncertainty.

[0095] The WTRU may be configured to use a modified RLM process, RLM criteria, and / or a set of RLM parameters for RLM. For example, the RLM process may be modified to distinguish between bad channels and busy channels. When the WTRU processes measurement samples, the WTRU may detect the level of uncertainty and / or ambiguity that may exist. The WTRU may affect (e.g., modify, adjust, or adapt) RLM based on, for example, channel conditions. The RLM process may include processing, handling, and / or reacting to ambiguous channels (e.g., channels that may be busy, may be bad, or may be both). The WTRU behavior may be configured and / or controlled, which may occur, for example, when the WTRU performs RLM in a shared spectrum.

[0096] As an example, determining whether RLF has occurred and / or the action to be taken based on an RLF declaration may depend on whether the WTRU has detected a bad channel or a busy channel. For example, a first RLM criterion (e.g., such as the number of consecutive out-of-sync conditions) may be used to determine that RLF has occurred due to a bad channel. A second RLM criterion (e.g., the number of consecutive skipped RLM RS transmissions and / or the number of consecutive out-of-sync indications) may be used to determine that RLF has occurred due to a busy channel. In some examples, declaring RLF based on a busy channel or based on a bad channel may cause the WTRU to perform the same action (e.g., the WTRU reacts to an RLF declared based on a busy channel in the same manner as for a bad channel). In other examples, the WTRU may react differently to an RLF declaration due to a busy channel than to an RLF declaration based on a bad channel.

[0097] The WTRU may use channel state information to influence (e.g., modify, adjust, or adapt) the RLM. A deployment in an unlicensed spectrum may be characterized by a shared frequency band. For example, two or more operators may share a frequency band and may or may not coordinate. Two or more 3GPP (e.g., LTE / NR) and / or non-3GPP wireless systems (e.g., WiFi or radar) may share a frequency band and may or may not coordinate. When a channel is busy, reference signals (e.g., reference signals related to RLM) may not be sent. The reference signals sent may be masked by interfering transmissions (one or more), for example, from hidden nodes. Reference signal measurements may be ambiguous (e.g., referred to as ambiguous channels). The WTRU may not be able to determine, for example, the nature of connectivity to a source cell in an ambiguous channel. For example, the channel (one or more) may be ambiguous, which may occur when the WTRU performs a measurement but cannot determine whether the channel has a poor measurement because the channel is busy or because the channel itself is poor from the WTRU's perspective. A channel may be busy if it may have acceptable quality but is being used by another technology or source at the time of measurement. If the channel is not in use during the measurement, but is still of poor quality, the channel itself may be bad from the WTRU's perspective.Channel state information may be obtained and / or determined, for example, to determine the nature of connectivity to a source cell in an ambiguous channel.

[0098] The WTRU may use channel state information to influence one or more aspects of radio link monitoring. The channel state information may be obtained, for example, from LBT or CCA or other signaling from the network. The WTRU may perform different actions in channels with different channel qualities (e.g., good, busy / fuzzy, or poor channel quality), for example based on the results of channel state awareness RLM. The different channel qualities may include good, busy / fuzzy, or poor channel quality. For example, the WTRU may not treat busy and / or fuzzy channels with the same rigor as poor channels.

[0099] The implementations described herein may be applicable to functions involved in evaluating connectivity with a network in a wireless system (e.g., LTE and / or NR) (e.g., RLM, and / or beam failure detection, etc.).

[0100] The WTRU may be configured to determine the channel state. For example, the channel state may be based on a determination of whether a transmission instance of an RLM-RS is skipped, or whether the RLM-RS is sent but the WTRU measures a bad channel based on the RLM-RS. The WTRU may distinguish between a bad channel and a busy channel, or at least detect a certain degree of uncertainty / ambiguity. For example, the channel state may correspond to a relative state of a channel (e.g., one or more of idle, busy, poor / bad, etc.). The state of a channel may be relatively clear (e.g., high quality, low usage, etc.). The state of a channel may be relatively busy (e.g., frequently used, good or poor quality when available, etc.). The state of a channel may be relatively poor / bad (e.g., low quality even when channel usage is low). The WTRU may evaluate the channel, for example, when processing a measurement sample, and make an evaluation as to whether the measurement corresponds to a bad channel and / or a bad channel. The WTRU may identify the level of uncertainty and / or ambiguity, for example, when processing a measurement sample, and make an identification as to whether the measurement corresponds to a bad channel and / or a bad channel. The WTRU may be configured to determine a channel state associated with a serving cell. The WTRU may use information about the channel state during RLM. The WTRU may determine that at least one transmission instance of an RLM-RS is skipped. For example, the channel state information may implicitly or explicitly indicate whether a transmission instance of an RLM-RS is skipped due to a busy channel. The channel state information may implicitly or explicitly indicate whether interference (e.g., from a hidden node) is masking the RLM-RS transmission.

[0101] Received signal strength indicator(s) (RSSI(s)) may be measured and / or used to determine the channel state (e.g., whether a transmission instance of an RLM-RS is skipped). The WTRU may be configured to perform a clear channel assessment (CCA) during RLM. For example, the WTRU may be configured to measure the RSSI in a time window (e.g., a predefined time window). The WTRU may be configured to measure the RSSI per symbol (e.g., a symbol associated with the RLM-RS transmission(s)). A relatively high RSSI value may indicate, for example, interference(s) from a non-serving node. For example, if the downlink quality associated with the RLM-RS is below a threshold and / or the RSSI is above a threshold, the WTRU may consider the channel busy or ambiguous. The WTRU may determine that a transmission instance of the RLM-RS is skipped based on the measurement result of the RSSI being greater than the threshold.

[0102] A zero power RS ​​(ZP-RS) may be measured and / or used to determine channel status (e.g., whether a transmission instance of an RLM-RS is skipped). The WTRU may be configured with one or more ZP-RS (e.g., a ZP-RS configuration). The ZP-RS(s) may be associated with a resource(s) (e.g., corresponding to a resource element) blanked by the gNB. The WTRU may expect blanked transmission(s) from the serving gNB in ​​the resource(s). The WTRU may be configured to measure power in the resource(s) (e.g., resource element) associated with the ZP-RS. The ZP-RS and the RLM-RS(s) may be configured in the same resource (e.g., symbol or subframe). For example, the ZP-RS and the RLM-RS(s) may be configured in the same resource block(s), subband(s), and / or BWP(s). The configured RLM-RS and ZP-RS may be associated (e.g., linked). For example, the interference associated with a particular resource may be evaluated using an association (e.g., link) between a configured RLM-RS and a ZP-RS. Non-zero power in the ZP-RS may indicate interference (e.g., from a non-serving node). If the received power in the ZP-RS is above a threshold, the WTRU may consider the channel busy or blurry. For example, the WTRU may measure the power on one or more resource elements that are configured to be blanked by the gNB. The WTRU may determine that a transmission instance of the RLM-RS is skipped based on the measured power on the resource element being above a threshold.

[0103] The WTRU may be configured to obtain further information about the interference source. For example, the WTRU may receive a configuration about one or more ZP-RSs, which may be used to derive information about the interference source. For example, if the ZP-RS configuration is specific to a serving cell, the detected and / or received power in the ZP-RS configuration (e.g., the ZP-RS in the ZP-RS configuration) may indicate non-serving cell interference. The ZP-RS (one or more) and / or ZP-RS configuration may be specific to cells belonging to the same operator and / or nodes that may be coordinated. If the ZP-RS is specific to a cell belonging to the same operator (e.g., which may be coordinated), the power detected and / or received in the ZP-RS may indicate uncoordinated interference. If the ZP-RS is specific to a cell belonging to a node that may be coordinated, the power detected and / or received in the ZP-RS may indicate uncoordinated interference. The ZP-RS may be specific to a 3GPP node. If the ZP-RS is specific to 3GPP nodes, the detected and / or received power in the ZP-RS may indicate interference from non-3GPP node(s) (eg, a WiFi access point or radar).

[0104] Retroactive compensation may be used to determine the channel status (e.g., whether a transmission instance of RLM-RS was skipped). For example, the WTRU may receive a signal indicating that a previously expected RLM-RS was skipped. The WTRU may receive information from the gNB indicating that a transmission instance of RLM-RS was skipped. The WTRU may receive information about the status of one or more RLM-RS transmission instances in the past (e.g., Tn, T-2n, etc.) at a time (e.g., T). For example, the gNB may skip the transmission of one or more RLM-RS (one or more). The skipped transmission instance of RLM-RS may be due to LBT failure. The WTRU may receive this information in signaling (e.g., an indication of the skipped transmission instance of RLM-RS). The WTRU may receive this information after the gNB reacquires the channel for transmission. The WTRU may determine, for example based on this information, that one or more RLM-RS transmissions in the past were skipped.

[0105] A WTRU may be configured to update RLM criteria (criteria), RLM procedure(s), and / or RLM parameter set (e.g., which is used to evaluate the RLF state of a cell) based on information indicating that a transmission instance of an RLM-RS is skipped. The WTRU may be configured to update RLM criteria, RLM procedures, and / or RLM parameter set based on information as described herein. In an example, the WTRU may perform RLM measurements on RLM-RS(s) transmitted on a cell. The cell may operate in an unlicensed spectrum. The WTRU may, for example, use RLM criteria to evaluate the RLF state of the cell. The WTRU may successfully measure the RLM-RS(s) transmitted on the cell. The RLM criteria may correspond to an RLM procedure using a set of RLM parameters. In an example, a gNB may skip a transmission instance of an RLM-RS (e.g., due to LBT failure). In this example, if retroactive compensation is not used, the WTRU may assume that the RLM-RS is transmitted and not received by the WTRU, thereby generating an OOS indication. Retroactive compensation may be used to update RLM criteria, RLM procedures, and / or RLM parameter set. The WTRU may determine that a transmission instance of the RLM-RS is skipped, for example, based on information (e.g., an indication) indicating that the transmission instance of the RLM-RS is skipped. The WTRU may update the RLM criteria. The updated RLM criteria may correspond to an updated RLM procedure that uses an updated set of RLM parameters. For example, a first RLM criterion may be based on an N310 counter and / or a T310 timer. The WTRU may use the first RLM criterion (e.g., in the case where the N310 counter and / or the T310 timer may be running) to evaluate the RLF state of a cell operating in an unlicensed spectrum. The WTRU may use a second RLM criterion, for example, where the N310 counter and the T310 timer may be decremented (e.g., if running) to evaluate the RLF state of a cell operating in an unlicensed spectrum. The first criterion may include a first condition requiring a first number of consecutive OOS indications to declare RLF. The second RLM criterion may include a second condition requiring a second number of consecutive OOS indications to declare RLF. The second number of consecutive OOS indications may be greater than the first number of consecutive OOS indications.

[0106] Figure 2 An example of a WTRU using an improved RLM implementation is shown. Figure 2 In the embodiment of the present invention, the WTRU may use a modified or adapted RLM implementation based on the channel state. The modified or adapted RLM implementation may be performed based on the channel state. The gNB may, for example, periodically send RLM-RS on the channel with an RLM-RS period. Figure 2As shown, the gNB may send RLM-RS204 and RLM-RS206. The WTRU may successfully receive RLM-RS204 and RLM-RS206. When the WTRU successfully receives RLM-RS204 and RLM-RS206, the WTRU may generate IS indications, respectively. The gNB may send the RLM-RS204 and RLM-RS206 in a periodicity. The periodicity may be represented by the distance between RLM-RS204 and RLM-RS206 in the time domain. The channel may be an unlicensed channel. The gNB may perform LBT before sending the RLM-RS. If LBT fails, the gNB may not be able to send the RLM-RS. As Figure 2 As shown, the gNB may have an LBT failure and / or may skip the transmission of RLM-RS 208. The WTRU may determine that the transmission instance of RLM-RS is skipped and / or generate an OOS indication. The gNB may have an LBT failure and / or may skip the transmission of RLM-RS 210. The gNB may have an LBT failure and / or may skip the transmission of RLM-RS 212. The WTRU may determine that the transmission instances of RLM-RS 210 and 212 are skipped and / or generate corresponding OOS indications. Next, the gNB may not have an LBT failure and / or may send RLM-RS 224. The WTRU may successfully receive RLM-RS 224 and generate corresponding IS indications. The gNB may have an LBT failure and / or may skip the transmission of RLM-RS 214. The WTRU may determine that the transmission instance of RLM-RS is skipped and / or generate corresponding OOS indications. Next, the gNB may not have an LBT failure and / or may send RLM-RS 216-220. The WTRU may successfully receive the RLM-RS 216 - 220 and generate a corresponding IS indication.

[0107] The WTRU may perform RLM using an RLM standard, an RLM procedure, or a set of RLM parameters. For example, the RLM parameters may include a timer / counter, a synchronization indicator, etc. The WTRU may fail due to, for example, a LBT failure (e.g., Figure 2 If the WTRU fails to receive the RLM-RS, the WTRU may use an adapted or modified RLM criterion, RLM procedure, or RLM parameter set. Figure 2As shown, when the WTRU receives RLM-RS204 and 206, the WTRU may use a first set of RLM standards 226. If the WTRU determines that a skipped RLM-RS208 is received, the WTRU may adapt the RLM standard or RLM process (e.g., using a second RLM standard or RLM process 228). For example, the WTRU may modify the RLM process by changing the RLM counter / timer based on channel occupancy, modifying the synchronization / out-of-sync count, applying a historical BLER value with a decay factor, etc. When the WTRU determines that the RLM-RS is skipped, the WTRU may modify the synchronization / out-of-sync count by introducing an out-of-sync indication or partially incrementing the OOS counter. For example, if the WTRU successfully receives the RLM-RS(s), the WTRU may use the RLM standard and / or RLM process before the WTRU performed the adaptation / modification. As shown Figure 2 As shown, if the WTRU determines that the WTRU successfully received one or more RLM-RS (e.g., RLM-RS 224), the WTRU may use an RLM standard or RLM procedure 230. The RLM standard or RLM procedure 230 may be the same as the first RLM standard or first RLM procedure 226.

[0108] Figure 3 An example flow chart that may be part of an RLM implementation is shown. The WTRU may monitor a channel to obtain an RLM-RS. For example, the WTRU may evaluate an RLF state based on successfully measuring the RLM-RS. The channel may be an unlicensed channel. The WTRU may determine whether an RLM-RS exists (e.g., within a time window). If an RLM-RS exists, the WTRU may use an RLM implementation and continue to monitor the RLM-RS on the channel. If an RLM-RS does not exist, the WTRU may adapt or modify the RLM implementation and / or perform RLM using the adapted or modified RLM implementation. For example, upon receiving an RLM-RS, the WTRU may return to the RLM implementation. The RLM implementation may include one or more of an RLM standard, an RLM procedure, or a set of RLM parameters.

[0109] The WTRU may receive information via signaling indicating that a transmission instance of an RLM-RS is skipped. The signaling may not specify an RLM-RS period or resource (e.g., it may be generic). For example, the signaling may indicate whether the gNB is transmitting during a certain time (e.g., a predefined time period). The signaling may include (e.g., be represented as) a bitmap at the granularity of a timeslot, a subframe, and / or a frame. The WTRU may determine (e.g., calculate) the state of an RLM-RS transmission instance based on, for example, the RLM-RS period and / or resource mapping.

[0110] The WTRU may receive signaling indicating information that a transmission instance of the RLM-RS is skipped via broadcast signaling or a dedicated message. In one example, the WTRU may receive signaling about the RLM-RS transmission state (e.g., whether the transmission instance of the RLM-RS is skipped) in broadcast signaling. The broadcast signaling may be sent using a SIB or a MIB. For example, the WTRU may receive the RLM-RS transmission state in a DCI (e.g., using a predefined RNTI for an indication of the RLM-RS transmission state). The WTRU may receive the signaling, for example, in a group common PDCCH. The signaling may be implicit (e.g., implicitly encoded in a slot format indicator (SFI)). The WTRU may receive signaling about the RLM-RS transmission state associated with a secondary node. The WTRU may receive signaling about the RLM-RS transmission state associated with a secondary node in a dedicated RRC message or broadcast signaling (e.g., SIB). The WTRU may receive, for example, a dedicated RRC message or broadcast signaling from a master node. The master node may be in a licensed spectrum.

[0111] The WTRU may be configured to determine that a transmission instance of the RLM-RS is skipped based on a characteristic associated with the RLM-RS transmission instance. The WTRU may perform sequence-based detection of a missing RLM-RS. The WTRU may be configured to determine that a transmission instance of the RLM-RS is skipped based on a failure to detect a characteristic associated with the RLM-RS transmission instance (e.g., during a transmission instance associated with the RLM-RS). For example, the WTRU may be configured to implicitly determine the state of an RLM-RS transmitted in the past (e.g., at time Tn) based on a characteristic associated with an RLM-RS transmission in the future (e.g., at time T).

[0112] A characteristic associated with an RLM-RS transmission instance may be a scrambling ID. The scrambling ID may be associated with an initial value of a pseudo-random sequence generator. For example, the WTRU may be configured with a set (e.g., an ordered set) of N scrambling IDs for a given RLM-RS. A transmission of the RLM-RS (e.g., each transmission) may be scrambled by selecting a scrambling ID from a preconfigured set of scrambling IDs (e.g., from an ordered set of N scrambling IDs). The selection of the scrambling ID may be cyclic for subsequent transmissions of the RLM-RS (e.g., each subsequent transmission). In an example, a first transmission of the RLM-RS may be scrambled by selecting a first scrambling ID, or may be skipped. For example, if the first transmission of the RLM-RS is skipped, transmissions after the first transmission may use the same first scrambling ID. The first transmission of the RLM-RS may be skipped due to an LBT failure (e.g., of the gNB). The WTRU may determine whether to skip and / or how many (e.g., up to N-1) RLM-RS transmission instances are skipped, for example, based on the scrambling ID associated with the transmission instance of the RLM-RS. The WTRU may calculate the difference between the assumed scrambling ID and the actual scrambling ID. For example, the assumed scrambling ID may be the scrambling ID that would be used if all previous (one or more) RLM-RS transmissions were successful. For example, the loop about the scrambling ID may be reset to further synchronize the use of the scrambling ID. For example, the loop about the scrambling ID may be reset at a predetermined period (e.g., a loop period). For example, the loop about the scrambling ID may be reset by starting from the first ID in the ordered group.

[0113] A characteristic associated with an RLM-RS transmission instance may be a resource mapping (e.g., a cyclic shift). For example, the WTRU may be configured with a cyclic shift that may be used to determine a time domain and / or frequency domain mapping of an RLM-RS (e.g., an RLM-RS sequence). A transmission of an RLM-RS (e.g., each transmission) may use a specific resource mapping. Subsequent RLM-RS transmissions (one or more) may be shifted in time and / or frequency, for example, using a predefined offset. For example, a transmission instance of an RLM-RS may use a first resource mapping (e.g., based on a first cyclic shift from a starting or reference time / frequency resource). A subsequent transmission instance of an RLM-RS may use a second resource mapping (e.g., based on a second cyclic shift). The second resource mapping may be offset from the first resource mapping by a predefined time and / or frequency offset. For example, if a transmission instance of an RLM-RS is skipped, the second resource mapping may not be offset from the first resource mapping by a predefined time and / or frequency offset. The WTRU may determine whether to skip an RLM-RS transmission instance and / or how many (e.g., up to N-1) RLM-RS transmission instances to skip, for example, based on a cyclic shift associated with the transmission instance of the RLM-RS. The WTRU may calculate the difference between the assumed cyclic shift and the actual cyclic shift. For example, the assumed cyclic shift may be the cyclic shift that would be used if all previous RLM-RS were successful. The resource mapping may be reset, for example, to further synchronize the cyclic shift. The resource mapping may be reset at a predetermined period (e.g., a cyclic period). The resource mapping may be reset to start from a predefined resource mapping.

[0114] Active compensation may be used to determine the channel status (e.g., whether a transmission instance of RLM-RS was skipped). The WTRU may receive information (e.g., at time T) about the status of one or more transmission instances of RLM-RS in the future (e.g., T+n, T+2n, etc.). In one example, the gNB may be close to exceeding the maximum channel occupancy time. The gNB may, for example, drain the channel to meet regulatory requirements. One or more transmission instances of RLM-RS may be skipped. The WTRU may be informed of the upcoming missing RLM-RS transmission (one or more), for example, based on signaling from the network. The WTRU may be configured to treat what the WTRU has learned, for example, as input. The WTRU may be configured to update the RLM process, RLM criteria and / or RLM parameter set for the upcoming RLM evaluation period (e.g., as active compensation).

[0115] The WTRU may be explicitly or implicitly informed of the absence of an upcoming RLM-RS transmission. For example, signaling regarding the upcoming absence of RLM-RS transmission(s) may be in a DCI (e.g., having a predefined RNTI). The signaling may be, for example, in a group common PDCCH. The signaling may be implicitly encoded in an SFI. Information regarding the absence of an upcoming RLM-RS transmission(s) may be signaled in a broadcast message. For example, a predefined sequence may be used to implicitly provide the information. The predetermined sequence may indicate the end of a transmission burst. The WTRU may determine (e.g., derive) information regarding the upcoming absence of RLM-RS transmission(s) based on the start time of the gNB transmission burst and / or the maximum channel occupancy time. The WTRU may calculate the start time of the gNB transmission burst associated with detecting the predetermined sequence (e.g., in a reference time / frequency resource). If the WTRU determines (eg, upon determining) to skip one or more upcoming RLM-RS, the WTRU may be configured to update the RLM procedure, RLM criteria and / or RLM parameter set (eg, to perform channel state aware RLM as described herein).

[0116] Eavesdropping may be used to determine the state of the channel (e.g., whether a transmission instance of RLM-RS was skipped). The WTRU may determine the state of the channel based on, for example, eavesdropped transmissions from a non-3GPP air interface. For example, a WiFi-capable WTRU connected to a 3GPP network may determine the state of a shared spectrum based on WiFi transmissions. One or more transmissions from WiFi may enable the WTRU to determine whether a channel is occupied by a non-3GPP interface. Examples of transmissions from WiFi may include ready to send (RTS) / clear to send (CTS) frames and / or virtual carrier sensing using a network allocation vector (NAV). The WTRU may determine how long a transmission from WiFi may last. The WTRU may determine whether a transmission from WiFi may overlap with a potential transmission instance of RLM-RS on a 3GPP interface. The WTRU may use this information to update the RLM process, RLM criteria, and / or RLM parameter sets (e.g., to perform channel state-aware RLM as described herein).

[0117] The WTRU may be configured to use signal detection to determine the channel state (e.g., whether a transmission instance of the RLM-RS is skipped). In one example, the WTRU may determine the channel state based on the detection of a wake-up signal and / or a preamble signal. The preamble signal may indicate the start of the COT. The WTRU may decode the signal (e.g., the preamble signal or the wake-up signal) and / or may determine the public land mobile network (PLMN) and / or physical cell identity (PCI) of the transmitter. The WTRU may determine, for example, based on the PLMN and / or PCI, whether the signal indicates that the WTRU's serving or neighboring cell has occupied the channel. If the signal includes an indication of the COT structure (e.g., an SFI), the WTRU may determine the channel state for the indicated time period. The WTRU may determine the channel state of (e.g., each) subband within the DL BWP separately.

[0118] The RLM process, RLM criteria and / or RLM parameter set may be updated to handle, process and / or react to ambiguous channels. The WTRU may be configured to monitor downlink quality based on RLM-RS measurement samples over a predetermined time period, for example as part of RLM. The predetermined time period may correspond to an evaluation period. The evaluation period may be a function of one or more of the following: the type of RLM-RS(s), the period of RLM-RS(s), the type of indication(s) (e.g., one or more IS or OOS indications), or a DRX configuration, etc. The WTRU may be configured to compare the estimated downlink quality with a threshold value (e.g., Qin and / or Qout). The WTRU may be configured to generate an IS / OOS indication based on the comparison. The WTRU may be configured to send an IS / OOS indication to a higher layer (e.g., RRC). A higher layer filter (e.g., a layer 3 filter) may be applied to the IS / OOS indication. The higher layer filter may have a preconfigured coefficient. Two consecutive indications from a lower layer (s) may be separated, for example, by at least one time interval. The time interval may be predetermined. The time interval may correspond to an indication interval. The indication interval may be a function of one or more of the following: the type of RLM-RS(s), the period of RLM-RS(s), the type of indication(s) (one or more IS or OOS indications), or the DRX configuration, etc.

[0119] For example, the measurement samples may be selected and / or scaled based on the channel state. The WTRU may be configured to receive RLM-RS(s) within a time window configured using, for example, an RLM-RS measurement timing configuration (RMTC). Being configured to receive RLM-RS(s) within a time window may take into account timing uncertainty (e.g., due to LBT). For example, if SSB is used as RLM-RS, the RMTC may correspond to an SS block-based measurement timing configuration (SMTC). The RMTC configuration may include one or more of a period, an offset, and a duration. The RMTC configuration may be expressed as a number of subframes. For example, the WTRU may expect RLM-RS in any symbol within the time window (e.g., which is defined by the RMTC).

[0120] During the evaluation period, measurement samples may be selected and / or scaled. The WTRU may be configured with an evaluation period. The evaluation period may be a multiple of the RLM-RS period or the period of the RMTC (e.g., in the case of RMTC). The RLM-RS may be sent multiple times during the evaluation period, for example. The measurement samples during the evaluation period may fluctuate due to, for example, channel ambiguity. The fluctuation may be rapid. The WTRU may be configured to derive channel quality based on, for example, at least n explicit measurement samples. The value of n may be configured, for example, preconfigured as a function of at least the RLM-RS period, indication type IS / OOS, or DRX configuration, etc.

[0121] The WTRU may be configured to determine, adjust and / or scale higher layer coefficients, for example, based on channel state determinations. For example, when the channel state is ambiguous, the WTRU may apply a smaller weight to the collected measurement samples. The WTRU may adjust higher layer coefficients based on the nature of the interference. For example, different weights may be applied for 3GPP interference and non-3GPP interference. Different weights may be applied for coordinated interference and uncoordinated interference. The WTRU may be configured to determine the probability of detecting (e.g., each) RLM-RS sample(s) within an evaluation period. The WTRU may adjust the weight of the layer 3 filter based on the probability of detecting the RLM-RS sample(s).

[0122] The WTRU may be configured to select, for example, a preconfigured number of measurement samples from a set of measurement samples. If the WTRU is configured to select a preconfigured number of measurement samples from a set of measurement samples, the WTRU may disregard samples as outliers, for example based on a preconfigured offset. The (e.g., preconfigured) offset may be BWP specific and / or may be received in the BWP configuration. The (e.g., preconfigured) number of measurement samples may be BWP specific and / or may be received in the BWP configuration.

[0123] The channel quality may be determined by using a fallback to a predefined downlink signal. The WTRU may be configured to use one or more predefined downlink signals for RLM, for example, when no RLM-RS is detected in the RMTC window. The WTRU may be configured to use one or more predefined downlink signals for RLM, for example, when more than a preconfigured number of measurement samples are ambiguous within an evaluation period. The WTRU may determine the channel quality based on RS(s) that are not explicitly configured for RLM. For example, the RS(s) may include a beam management RS, a CSI-RS configured for CSI reporting, and / or an SSB (if only CSI-RS is configured for RLM). The RS may be quasi-co-located (QCLed) with at least one preconfigured RLM-RS. The WTRU may determine the channel quality based on the successful reception of DCI associated with a broadcast transmission (e.g., SI-RNTI in a common search space). For example, if a preconfigured number of DCIs are successfully decoded within a time period, the WTRU may generate an IS indication. The time period may include an indication interval or an evaluation interval. If a preconfigured number of DCIs are not successfully decoded within the time period, an OOS indication may be generated. The WTRU may monitor the RLM-RS(s) and / or predefined downlink signals within the RMTC window. The WTRU may monitor the RLM-RS(s) within the RMTC window and fall back to monitoring the predefined downlink signals outside the RMTC window. The WTRU may monitor the predefined downlink signals outside the RMTC window until the next RMTC window or the condition for generating IS / OOS indication(s) is met (e.g., whichever is earlier).

[0124] The WTRU may be configured with multiple (e.g., X) RLM-RS for RLM. The RLM-RS (e.g., each RLM-RS) may be associated with a transmit beam. The WTRU may determine whether to generate IS, OOS, or NS based on, for example, the channel status among the multiple RLM-RS. For example, if more than n RLM-RS results are ambiguous, the WTRU may be configured to generate NS(s). If the number of RLM-RS with ambiguous results is greater than the number of RLM-RS with OOS(s), the WTRU may generate NS(s).

[0125] The WTRU may be configured to select n RLM-RSs from the X configured RLM-RSs for RLM evaluation based on, for example, channel status associated with the RLM-RS(s) (e.g., a determination as to whether the RLM-RSs are skipped). For example, when the WTRU determines that an SSB transmission is skipped (e.g., due to LBT), the WTRU may be configured to perform RLM evaluation based on CSI-RS resources that are quasi-co-located with the SSB.

[0126] A block error rate (BLER) may be determined during an ambiguous channel. The WTRU may be configured to determine the BLER during ambiguous channel conditions based on, for example, previous BLER values ​​(one or more) associated with the channel. For example, the WTRU may infer (e.g., calculate) the BLER based on a weighted average of the first n BLER values ​​of the channel. The WTRU may add a preconfigured negative offset to the average BLER value. For example, the negative offset may be incremented during an indication interval (e.g., each indication interval). The increment of the negative offset may be an additive increment and / or a multiplicative increment. The negative offset may be, for example, a function of one or more of the following: the number of clear measurement samples collected during an evaluation period, RLM-RS measurement results, one or more channel measurements (e.g., interference level), the number of lost transmission opportunities, or one or more interference sources (e.g., different values ​​for 3GPP interference and non-3GPP interference), etc. When an IS indication is received, the negative offset may be reset to an initial value. The WTRU may be configured to generate an IS / OOS / NS indication (one or more) based on, for example, comparing the calculated BLER value to a Qin / Qout threshold.

[0127] An indication associated with an ambiguous channel may be generated (e.g., no synchronization (NS)). The WTRU may be configured to generate an indication other than the IS and OOS indication(s) (e.g., the NS indication). The WTRU may be configured to generate the indication to notify higher layers of ambiguous channel conditions (e.g., during an RLM procedure). For example, when a channel state is determined to be ambiguous using one or more of the examples described herein (e.g., when it is determined that an RLM-RS is not received), a NS indication may be generated. The NS indication may be generated when lower layers may not be able to conclusively determine channel quality, for example, due to a lack of RLM-RS transmission(s). The NS indication may be generated when lower layers may not be able to conclusively determine channel quality, for example, due to masking of the RLM-RS in a busy channel.

[0128] The WTRU may be configured to track the number of NS indications that the WTRU receives from lower layers. For example, the WTRU may maintain an NS counter regarding the number of (e.g., consecutive) NS indications. The NS counter may include N312 or NS310. The WTRU may be configured to reset the NS counter, for example, upon receiving an IS indication. The WTRU may be configured not to reset the NS counter, for example, upon receiving an OOS indication. The WTRU may be configured to perform a predefined action, which may occur, for example, when the NS counter reaches a preconfigured maximum value. Continuous NS indications may indicate that the channel has been busy for a period of time (e.g., a relatively long period of time). For example, the channel may have been busy for a period of time due to a relatively high density of competing nodes and / or a relatively high channel load that results in failed transmissions. If the timer is not already running, the WTRU may start the timer (e.g., T310). When the timer (e.g., T310) is running and the NS counter reaches a maximum value, the WTRU may trigger an RLF. When the sum of the OOS counter and the NS counter reaches a maximum value, the WTRU may start the timer (e.g., T310). When a NS indication is received, the WTRU may exclude the time interval from the timer. For example, when T310 is running, when a NS indication is received, the WTRU may exclude the time interval from T310. When a NS indication is received, the WTRU may pause the timer (e.g., T310). The WTRU may interpret the NS indication based on the state of the timer (e.g., T310). For example, when T310 is running, the WTRU may treat the NS indication as an IS indication. When T310 is not running, the WTRU may treat the NS indication as an OOS indication.

[0129] The WTRU may be configured to interpret the NS indication differently based on previous indications. In an example, the WTRU may be configured to interpret the NS indication based on previous indications, for example, from a lower layer. For example, if the number of OOS indications in "n" previous indications from the lower layer is greater than a number (e.g., a preconfigured number), the WTRU may interpret the NS indication as an OOS indication. If the number of IS indications in "n" previous indications from the lower layer is greater than a number (e.g., a preconfigured number), the WTRU may interpret the NS indication as an IS indication. If the number of NS indications in "n" previous indications from the lower layer is greater than a number (e.g., a preconfigured number), the WTRU may start a timer. If no IS / OOS indication is received before the timer expires, the WTRU may be configured to start a T310 timer or trigger an RLF (e.g., if T310 is already running).

[0130] A counter (e.g., an OOS counter) may be incremented by a fractional value. For example, the WTRU may be configured to increase the OOS counter by a fractional value (e.g., by less than 1) during ambiguous channel conditions. The WTRU may be configured (e.g., preconfigured) with a fractional value. The WTRU may receive a fractional value in an RRC signal or via a system information broadcast. The WTRU may determine the fractional value based on, for example, one or more of: RLM-RS measurement results, one or more channel measurements (e.g., interference level), the number of lost transmission opportunities, or interference sources (e.g., different values ​​for 3GPP interference and non-3GPP interference), etc. The WTRU may be configured to use a fractional increment (e.g., increase the OOS counter by a fractional value) when an NS indication is received. The WTRU may be configured to use a fractional increment (e.g., increase the OOS counter by a fractional value) when an OOS indication is received and the channel state is determined to be ambiguous (e.g., using one or more of the examples described herein).

[0131] The WTRU may be configured to use zero power resources for RLM (e.g., evaluation). For example, zero power resources may be time / frequency resources on which a network node does not transmit signals (e.g., blanked). CSI-IM (e.g., which may also be referred to as RLM-IM) may be an example of a zero power resource. For example, in addition to RLM-RS (one or more), the WTRU may be configured with RLM channel state information interference management (CSI-IM) resources in a DL BWP for RLM. The WTRU may be configured with RLM CSI-IM resources in (e.g., each) DL BWP. The WTRU may monitor the CSI-IM resources in the active DL BWP. The WTRU may evaluate the interference level experienced in the active DL BWP based on the monitoring of the CSI-IM resources. The CSI-IM resources may be configured on the same resources (e.g., RBs) as the RLM-RS (one or more). The WTRU may perform L1 measurements on ZP resources and / or non-ZP resources. The WTRU may maintain counters for resources of different types (e.g., each type). For example, the WTRU may maintain a counter for each of the ZP resource(s) and non-ZP resource(s).

[0132] In one example, the WTRU may generate and / or send (e.g., to a higher layer) an indication based on an assessment of the interference level on the CSI-IM resources. The WTRU may send an indication other than an IS indication(s) and an OOS indication(s). For example, the indication may be an unknown synchronization (US) indication. If the higher layer receives multiple US indications (e.g., upon receiving N US indications), the higher layer may restart the RLF timer. The WTRU may be configured with a threshold (e.g., a US-specific counter threshold) associated with the US indication. If the threshold is reached (e.g., upon reaching the US-specific counter threshold), the WTRU may declare an RLF.

[0133] In one example, the WTRU may indicate an IS and / or OOS indication to a higher layer. For example, the WTRU may send only a conventional IS-OOS (e.g., may not use a US indication). The OOS indication may be generated and / or sent based on (e.g., subject to) a measurement result on a CSI-IM resource. The WTRU may be configured to suppress sending an OOS indication if the measurement result (one or more) on the CSI-IM resource is above a threshold. In an example, the CSI-IM measurement above a threshold may indicate an LBT failure and / or may not indicate a bad channel condition. The WTRU may send the IS, skip the indication, and / or transmit an NS indication. As an example, the WTRU may send the IS, skip the indication, and / or transmit a no-sync indication without considering the CSI-IM measurement result. For example, if the measurement of the RLM-RS meets the criteria for IS, skip the indication, and / or transmit the NS indication, the WTRU may send the IS, skip the indication, and / or transmit the NS indication without considering the CSI-IM measurement result. In one example, the OOS indication may be conditional on the CSI-IM measurement. Whether to send IS, skip the indication and / or send NS indication may not be conditional on CSI-IM measurement.

[0134] The WTRU may be configured to receive a configuration of a RLM-RS per subband (e.g., for a configured DL BWP). For example, a configuration of a RLM-RS per subband may be received for each configured DL BWP. The WTRU may determine which RLM-RS to monitor for RLM, for example, based on RSSI and / or channel occupancy (CO) measurements on corresponding subbands (e.g., subbands corresponding to the received configuration for RLM-RS(s)). For example, if the RSSI or CO measurement in a given subband of an active DL BWP is above a configured threshold, the WTRU may not consider the configured RLM-RS resources within the subband for RLM. The WTRU may perform RLM evaluation on a subband with low load. On a subband with low load, the RSSI or CO measurement may be below a configured threshold. The WTRU may be configured to refrain from performing RLM on a subband indicated as busy or loaded, for example, based on the RSSI or CO measurement.

[0135] In one example, if the contention metric in one or more subbands in an active DL BWP is above a threshold, the WTRU may activate pre-configured RLM-RS resources in other subbands of the active DL BWP. For example, the WTRU may activate the pre-configured RLM-RS resources when the contention metric in each subband currently being measured is above a threshold.

[0136] In one example, the WTRU may maintain multiple RLM loops. As used herein, a loop may refer to an RLM process (e.g., an independent RLM process) with one or more associated RLM resources, Qin-Qout thresholds, timers, and / or counters. For example, the WTRU may maintain one RLM loop for each subband. When one or more subbands of an active DL BWP reach the RLF criteria (e.g., N OOS indications in each subband), the WTRU may trigger RLF. For example, when all subbands of an active DL BWP reach the RLF criteria, the RLF may be triggered.

[0137] The WTRU may be configured to use aperiodic or semi-persistent CSI-RS resources for RLM. Aperiodic or semi-persistent CSI-RS transmission may be used for RLM to handle the uncertainty of periodic CSI-RS transmission due to LBT. Periodic CSI-RS transmission may be uncertain, for example, due to LBT. For example, aperiodic or semi-persistent CSI-RS transmission for RLM may be used to handle the uncertainty. The WTRU may be pre-configured with multiple CSI-RS resources, for example in different subbands. The WTRU may expect to receive a MAC CE or DCI. The WTRU may activate / deactivate a set of CSI-RS(s) based on the LBT results and / or received MAC CE or DCI in the corresponding subband of the active DL BWP. For example, when the channel load on the active DL BWP exceeds a certain level (e.g., indicating that the configured periodic RLM-RS(s) are uncertain), the WTRU may use one or more aperiodic or semi-persistent CSI-RS resources for RLM. If the WTRU does not receive a MAC CE or DCI within a time window (e.g., a preconfigured time window) (e.g., due to bad channel conditions), the WTRU may send an OS indication to higher layers for that time window. The preconfigured time window may be, for example, an RLM evaluation period.

[0138] A WTRU may receive a DCI for an aperiodic CSI-RS transmission(s) (e.g., when a channel is acquired by a gNB). A WTRU may receive an indication that the WTRU may perform RLM on the indicated RS (e.g., the aperiodic CSI-RS transmission(s)). The WTRU may receive the indication in a DCI. The DCI may be WTRU-specific or common to multiple WTRUs configured with a DL BWP containing the transmitted aperiodic CSI-RS resources. For example, the DL BWP may be an active DL BWP.

[0139] The WTRU may be configured to perform channel state aware RLM based on the state of a timer (e.g., T310). The WTRU may be configured to perform one or more examples described herein, for example as a function of the state of a timer (e.g., T310) associated with RLF. For example, the WTRU may be configured to perform conventional RLM when T310 is not running. When T310 is running, the WTRU may switch to channel state aware RLM. The WTRU may determine an increment value of an IS counter, for example, based on the state of timer T310. In one example, when T310 is running, a first increment value (e.g., less than 1) may be used, and when T310 is not running, a second increment value (e.g., 1) may be used.

[0140] The WTRU may be configured to perform autonomous UL triggering of RLM-related signals and / or RLM-RS reception in a portion of the UL grant abandoned by the WTRU. The WTRU may be configured to abandon all or part of the UL grant based on, for example, the status of past RLM-RS transmissions. The UL grant may be dynamically or semi-statically configured for the WTRU. The WTRU may autonomously acquire a channel, for example, after a complete LBT. For example, the WTRU may have failed to receive one or more RLM-RS in a previous period. The WTRU RLM counter (e.g., N310 or NS counter) may reach a condition (e.g., a critical condition, which includes a preconfigured critical condition). The WTRU RLM timer (e.g., T310) may reach a condition (e.g., a critical condition, which includes a preconfigured critical condition). Upon one or more triggers (e.g., as described herein), the WTRU may transmit an indication in the UL indicating that the RLM-RS was not reliably received in the previous time period, and / or may abandon the UL grant. The trigger may include a failure of the WTRU to receive one or more RLM-RS in a previous time period, or a WTRU RLM counter or RLM timer reaching a condition (e.g., a critical condition). The network may use the channel to send RLM-RS(s) and / or signals similar to RLM-RS(s). The WTRU may be configured to monitor the RLM-RS signals in the remaining portion of the UL grant. The WTRU may indicate to the network the portion of the transmission opportunity in which the RLM-RS may be transmitted. For example, the WTRU may transmit an autonomous uplink (AUL)-UCI to indicate to the network the portion of the transmission opportunity. The WTRU may transmit a bitmap regarding the most recently received RLM-RS (e.g., in the AUL).

[0141] The WTRU may be configured to adapt one or more counters and / or timers, for example, based on channel occupancy. The counters and / or timers may be used as part of an RLM procedure. A WTRU (e.g., a WTRU that is performing RLM) may apply a set of counters and timers based on current, past and / or observed channel occupancy. The timers (e.g., N310, N311 and / or T310) may depend on current, past and / or observed channel occupancy. For example, RLM parameters may be set such that T310 has a longer duration for higher channel occupancy and a lower duration for lower channel occupancy. Using different sets of RLM parameters and / or different RLM procedures may be used to avoid premature declaration of RLF (e.g., due to failure of the network to provide RLM-RS under high channel load).

[0142] A higher layer (e.g., RRC) may configure one or more RLM parameters with more than one value. The RLM parameters may include at least one of the N310 and N311 counters and the T310 timer. For example, T310 may be configured to have two possible values. The WTRU may determine appropriate values ​​for the one or more RLM parameters based on a metric or indication (e.g., as described herein). The WTRU may multiply the value of the RLM parameter by a factor (e.g., based on the indication). For example, the WTRU may double the length of the T310 timer by applying a factor of 2 to the T310 timer. The factor may be predefined and / or configured. For example, a multiplication factor may be applied when it is determined that a channel is considered busy or occupied. .

[0143] A metric may be determined (e.g., defined). The metric may correspond to an estimate and / or measurement of the channel occupancy. For example, a channel occupancy metric may be used that includes a percentage of samples with an RSSI above a threshold. The WTRU may be configured with at least one threshold for the metric. The WTRU may apply the value of the one or more RLM parameters as a function of the metric value compared to the at least one threshold. For example, a single channel occupancy threshold and two values ​​of T310 may be configured. If the channel occupancy is below the threshold, the WTRU may apply a first value, and if the channel occupancy is above the threshold, the WTRU may apply a second value. The at least one threshold may be predefined or configured by a higher layer. The at least one threshold may be the same as the threshold used to trigger a measurement report on the channel occupancy.

[0144] The WTRU may determine appropriate values ​​for the one or more RLM parameters based on a dynamic indication from the network. The indication may be received via a MAC CE. The indication may be received via a PDCCH received from a common search space or a WTRU-specific search space. For example, the indication may be provided in a common DCI (e.g., the same DCI containing the SFI). The indication may be provided in a DCI containing an existence indication (e.g., the same DCI). The indication may be provided in a separate DCI. The information may include an index to (e.g., consisting of) the appropriate value. The information may include a channel occupancy measurement (e.g., performed by the network). The WTRU may determine the appropriate value based on one or more of the indicated channel occupancy (from the PDCCH), the measured channel occupancy, or at least one threshold. As an example, the WTRU may determine the appropriate value based on the indicated channel occupancy (e.g., from the PDCCH) and at least one threshold. The WTRU may determine the appropriate value based on the measured channel occupancy and at least one threshold. For example, the WTRU may determine the appropriate value based on whether a maximum of two channel occupancies (eg, the indicated channel occupancy and the measured channel occupancy) is above a threshold.

[0145] The WTRU may determine appropriate values ​​of the one or more RLM parameters based on attributes of the RLM-RS. For example, the attributes of the RLM-RS may include a scrambling ID. The WTRU may attempt to detect the RLM-RS using at least one attribute. The WTRU may determine a value for the at least one attribute based on a highest likelihood (e.g., highest correlation). For example, if the RLM-RS is detected using a first scrambling ID, the WTRU may apply a first value of T310. If the RLM-RS is detected using a second scrambling ID, the WTRU may apply a second value of T310. For example, the value of the at least one attribute may be configured by a higher layer.

[0146] The WTRU may be configured with two or more RLM-RS resources. The resource (e.g., each resource) may be associated with a corresponding value of an RLM parameter. The WTRU may perform RLM independently on the RLM-RS resource (one or more) (e.g., each RLM-RS resource). The WTRU may declare RLF when the T310 timer has expired for the RLM-RS resource and the channel quality has not recovered since the last time T310 expired for the resource. For example, the WTRU may declare RLF only when the T310 timer has expired for all RLM-RS resources and the channel quality has not recovered since the last time T310 expired for the resource (e.g., each resource). The WTRU may determine that the channel quality has not recovered based on receiving at least one N311 synchronization indication (one or more). The network may select the RLM-RS resource, for example, based on channel occupancy. For example, the network may select the RLM-RS resource based on the RLM-RS transmission frequency caused by the failure to access the channel.

[0147] For example, when T310 is running for the first RLM-RS resource, the WTRU may start monitoring the second RLM-RS resource. For example, the WTRU may start monitoring the second RLM-RS resource only when T310 is running for the first RLM-RS resource. The first RLM-RS and the second RLM-RS may be configured with different periods. If the first RLM-RS and the second RLM-RS are configured with different periods, the WTRU may monitor the RLM-RS configured with a low period when (e.g., only when) a problem occurs with the RLM-RS configured with a high period. For example, if the WTRU fails to detect the RLM-RS configured with a high period above the quality threshold, the WTRU may monitor the RLM-RS configured with a low period. This approach may be more battery efficient. For example, the WTRU may monitor the RLM-RS configured with a low period only when the channel becomes busy. When the channel becomes busy (e.g., due to LBT failure), one or more high period RLM-RS resources may be discarded.

[0148] The WTRU may be configured to declare an RLF if a channel that the WTRU is using is busy, for example, for an extended period. As an example, if the WTRU fails to acquire a channel for an uplink after a given amount of time, the WTRU may declare an RLF. If the WTRU fails to acquire a channel for an uplink after multiple failed attempts to acquire the channel (e.g., multiple LBT failures), the WTRU may declare an RLF. The WTRU may transmit in an unlicensed channel. The WTRU may be configured to verify that the channel is idle (e.g., at least within a sensing interval) before the WTRU transmits. LBT failures may include situations where the channel is assessed to be non-idle (e.g., based on energy detection). For example, an LBT failure may correspond to a situation where the channel is assessed to be non-idle for at least a determined time interval prior to transmission.

[0149] The WTRU may be configured to declare RLF based on LBT failures (e.g., too many LBT failures). The WTRU may be configured to monitor channel availability for UL transmissions in a connected state. The WTRU may be configured to declare RLF based on a trigger (e.g., a trigger associated with channel availability). For example, the WTRU may be configured to declare RLF if a channel cannot be acquired for UL transmission within a predefined time. The WTRU may be configured to declare RLF if a channel cannot be acquired for UL transmission in multiple attempts (e.g., due to LBT failures). The WTRU may avoid being stuck in a good but busy channel (e.g., using the methods herein).

[0150] The WTRU may be configured to, for example, postpone transmission to a future time when the channel is idle when LBT fails. The WTRU may be configured to maintain a count of LBT failures that caused the postponed transmission. As used herein, the terms LBT failure counter, skip transmission counter, postpone transmission counter, and transmission attempt counter may be used interchangeably. In one example, the WTRU may be configured to maintain a common LBT failure counter across one or more UL channels. For example, the common LBT failure counter may be maintained on all UL channels. The UL channels may include, for example, a physical random access channel (PRACH), a PUCCH, and / or a PUSCH. In one example, the WTRU may be configured to maintain a failed LBT counter, such as a failed LBT counter specific to the UL channel associated with the transmission. For example, the WTRU may maintain separate counters for one or more of the PRACH, PUCCH, and PUSCH channels. The WTRU may be configured to declare RLF when a maximum value of at least one of the LBT failure counters (e.g., which is pre-configured / pre-defined) is reached. The WTRU may be configured to declare RLF, for example, based on the sum of two or more counters reaching a maximum value.

[0151] A trigger related to RLF may be generated based on a postponed preamble transmission. The WTRU may trigger an RLF based on a postponed preamble transmission (e.g., too many postponed preamble transmissions). The WTRU may be configured to determine (e.g., ensure) the success of LBT, for example, before the WTRU performs a preamble transmission. For example, the WTRU may use a counter to keep a count of the number of preamble transmissions that are postponed or skipped due to failed LBT (one or more). The counter may be different from the preamble transmission counter or the power ramp counter (e.g., skip preamble transmission counter). The counter may be a skip preamble transmission counter. The WTRU may be configured to increment the skip preamble transmission counter if the preamble transmission is cancelled when the LBT fails. The WTRU may be configured to trigger an RLF if the skip preamble transmission counter reaches a value (e.g., a preconfigured value). The WTRU may reset the skip preamble transmission counter if a random access response (RAR) is received (e.g., successfully received). The WTRU may be configured to trigger RLF if the sum of the skipped preamble transmission counter and the preamble transmission counter is above a value (e.g., a preconfigured value). The WTRU may be configured to increase the preamble transmission counter by a fractional value if the preamble transmission is skipped due to LBT failure. The fractional value may be less than one. For example, the fractional value may be configured via RRC signaling or in a system information broadcast.

[0152] For example, once a timer (e.g., skip preamble timer) expires, the WTRU may trigger RLF. The WTRU may be configured to start a timer when the preamble transmission is postponed (e.g., due to LBT failure). The WTRU may stop the timer if the lower layers indicate that the preamble was transmitted.

[0153] Indications about LBT results and / or transmission status may be defined and / or sent from a lower layer to a MAC (e.g., a MAC layer). As an example, upon receiving an indication notifying a transmission failure due to LBT, the MAC layer may be configured to increment the skip preamble counter and / or may start a skip preamble timer.

[0154] A trigger related to RLF may be generated based on deferred UL transmissions (e.g., too many deferred UL transmissions). The WTRU may be configured to determine (e.g., ensure) a successful LBT, for example, before the WTRU performs PUSCH and / or PUCCH transmission(s). The WTRU may perform LBT in a cell (e.g., which operates in an unlicensed spectrum). The WTRU may determine to defer and / or skip UL transmissions, for example, based on a determination of a failed LBT. The WTRU may determine that the number of deferred UL transmissions exceeds a threshold. The WTRU may send an indication of RLF based on a determination that the number of deferred UL transmissions exceeds the threshold. The WTRU may determine that the UL access delay exceeds a threshold. The WTRU may send an indication of RLF based on a determination that the UL access delay exceeds a threshold. The uplink transmission may include a MSG3 transmission or any other UL-SCH transmission. The example of skipped preamble transmission(s) (e.g., as described herein) may be applied to skipped PUSCH and / or deferred PUCCH transmission(s). The counters and / or timers may be separate for PUCCH and PUSCH. The threshold may be associated with a UL channel (eg, specific to the UL channel).The WTRU may be configured to maintain a counter for deferred UL transmissions.

[0155] The WTRU may be configured to determine the fractional increment of the OOS counter based on the number of transmissions. The WTRU may be configured to determine the fractional increment of the OOS counter based on the number of skipped preamble transmissions. The WTRU may be configured to determine the fractional increment of the OOS counter based on the number of skipped PUSCH transmissions. The WTRU may be configured to determine the fractional increment of the OOS counter based on the number of skipped PUCCH transmissions. If the number of skipped transmissions is above a threshold, the WTRU may interpret the NS indication as an OOS indication. If the number of skipped preamble transmissions is above a threshold, the WTRU may interpret the NS indication as an OOS indication. If the number of skipped PUSCH transmissions is above a threshold, the WTRU may interpret the NS indication as an OOS indication. If the number of skipped PUCCH transmissions is above a threshold, the WTRU may interpret the NS indication as an OOS indication.

[0156] The WTRU may be configured to maintain a deferred UL transmission counter (e.g., LBT failure counter). In an example, the WTRU transmission opportunities may be frequent or may occur close to each other. For example, if a common counter is configured for multiple UL channels, incrementing the LBT failure counter at each LBT failure may result in an early declaration of RLF. The WTRU may increment the LBT failure counter fractionally upon LBT failure, and / or n LBT failures may result in an increment of the counter. For example, the WTRU may increment the LBT failure counter fractionally upon each LBT failure. In an example, the WTRU may increment the LBT failure counter (e.g., once) upon n consecutive LBT failures. The n consecutive LBT failures may not have an LBT success in between. The WTRU may be configured to refrain from incrementing the LBT failure counter if n consecutive LBT failures do not occur. The increment of the counter may correspond to (e.g., be specific to) an UL channel.

[0157] The WTRU may be configured to increment the LBT failure counter based on a given UL channel. The WTRU may be configured to maintain a common counter for LBT failures during UL transmissions. For example, the common counter may be used for LBT failures during any UL transmission and / or for transmissions on any UL channel. The increments to the counter may be a function of a specific UL channel (e.g., a specific attribute or characteristic of the UL channel). As an example, the WTRU may be configured to increment the counter based on a periodicity of transmission opportunities associated with the UL channel. For example, a smaller increment may be added when an LBT failure occurs during a frequently occurring UL channel. A larger increment may be added when an LBT failure occurs during a less frequently occurring UL channel. The increment may be pre-configured (e.g., in a system information broadcast or RRC configuration). The WTRU may determine the increment, for example, based on a periodicity of transmission opportunities associated with the UL channel.

[0158] The WTRU may be configured to implement a variety of rules to control when the LBT failure counter is incremented. For example, one or more timers may be used to determine whether the LBT failure counter is to be incremented based on observed or detected criteria (criteria). The use of the one or more timers may avoid frequent increments of the LBT failure counter. In one example, the WTRU may be configured to increment the LBT failure counter at most once within a time interval. When the LBT failure counter is incremented, the WTRU may start a timer. If the timer is running, the WTRU may not increment the LBT failure counter during subsequent LBT failures. If the timer is not running or expires and an LBT failure occurs, the WTRU may increment the LBT failure counter and / or start the timer again.

[0159] The WTRU may be configured to increment the LBT failure counter if n or more LBT failures occur within a time interval. For example, if n or more consecutive LBT failures are observed within a time interval, the WTRU may increment the LBT failure counter.

[0160] The duration of the timer and / or the value of n may be configured by system information broadcast or RRC configuration.In an example, the WTRU may be configured to determine the value of n and / or the timer based on the logical channel and / or quality of service that triggered the UL transmission.

[0161] The WTRU may be configured to reset the LBT failure counter based on a specific criterion (criteria). The WTRU may be configured to reset the LBT failure counter if the WTRU determines that the channel is available for transmission. For example, if the CCA is successful, the WTRU may reset the LBT failure counter. If an UL transmission is performed, the WTRU may reset the LBT failure counter. The UL transmission may be, for example, a preamble, a PUCCH, or a PUSCH transmission. The WTRU may reset the counter if N CCA successes are detected and / or N UL transmissions are performed. For example, the WTRU may be configured to suppress resetting the counter when N CCA successes are not detected and / or N UL transmissions are not performed. If the counter is reset, the WTRU may stop the timer associated with the LBT failure count.

[0162] The WTRU may be configured to reset the LBT failure counter if a response (eg, RAR) is received to the preamble transmission.

[0163] The WTRU may be configured to have RLM behavior as a function of LBT failures. In an example, functionality related to counting LBT failures and / or affecting WTRU behavior based on LBT failures may be modeled as RLM (eg, RLM procedures).

[0164] When the LBT counter value reaches a threshold (e.g., a preconfigured maximum value), the WTRU may trigger an RLF. The WTRU may trigger an RLF based on a combination of the LBT failure counter and the status of the RLM procedure (e.g., based on an IS / OOS indication). For example, when a timer associated with RLM is running, the WTRU may trigger an RLF based on a maximum number of LBT failures. The timer may be, for example, T310. For example, the WTRU may be configured to refrain from triggering an RLF based on the maximum number of LBT failures when the timer associated with RLM is not running.

[0165] In one example, the WTRU may start a timer when the LBT failure counter reaches a preconfigured value. When a successful transmission (e.g., preamble transmission and / or any other UL transmission) cannot be performed within the expiration of the timer, the WTRU may trigger an RLF. One or more states regarding RLM behavior may be configured for the WTRU. For example, the WTRU may be configured with two states regarding RLM behavior. In the first state, the WTRU may monitor the state of the channel. If the LBT counter indicates that the channel is busy, the WTRU may enter a second state. In the second state (e.g., modeled as a recovery phase), the WTRU may attempt a successful transmission within a time period. If no UL transmission is performed within the expiration of the timer, the WTRU may declare an RLF.

[0166] The WTRU may be configured to perform BWP failure detection and / or recovery using autonomous BWP switching. The WTRU may be configured to perform LBT at the granularity of BWP(s). Different BWPs associated with a serving cell may have varying channel conditions, load(s), or interference. The WTRU may be configured to perform RLM based on RLM-RS(s) restricted to an active BWP. The WTRU may be configured to declare a BWP failure when RLF is detected in the active BWP, for example based on one or more RLF triggers described herein. For example, a BWP failure may be declared when more than n RLM-RS resources are not transmitted (e.g., within more than x indication periods). The WTRU may be configured to autonomously switch to a different BWP belonging to the same serving cell, for example, when RLF is detected in an active BWP. The WTRU may switch to a BWP selected from a plurality of BWPs (e.g., pre-configured BWPs) for the WTRU. The WTRU may select the BWP based on the quality of the BWP(s) (e.g., based on SSB and / or CSI-RS measurements). The WTRU may select the BWP with the earliest channel availability. The WTRU may select a BWP with low channel load and / or channel occupancy (e.g., based on RSSI and / or ZP-RS measurements). The WTRU may select a default BWP or a fallback BWP (e.g., which is specifically preconfigured for the WTRU). The WTRU may indicate an autonomous BWP switch to the network using a RA procedure that includes the selection of a preamble belonging to the BWP to which the WTRU is switching. The WTRU may indicate the reason for the autonomous BWP switch (e.g., channel busy for a predefined time or RSSI results).

[0167] The WTRU may be configured to take corrective action when the WTRU receives an indication that the channel load is above a threshold. The corrective action may include, for example, at least one of declaring an RLF or applying a stored handover configuration (e.g., conditional handover). The indication may include, for example, detecting that a configured RS is above a threshold or decoding a DCI indicating a high load condition. The WTRU may apply the corrective action if the WTRU fails to detect an RS (e.g., RLM-RS) above a threshold, or if T310 is running or has expired.

[0168] The channel status may be reported. The network may configure RLM-RS resources for the WTRU. The WTRU may be configured to report BWP-specific RSSI measurements for the active BWP and one or more configured BWPs. The WTRU may be configured to report BWP-specific ZP-RS measurements for the active BWP and one or more configured BWPs. The WTRU may be configured to trigger the reporting based on, for example, the expiration of a periodic timer and / or based on a request from the network. The reporting may be configured as an event triggered reporting. These events may include, for example, the active BWP RSSI is above or below a threshold, the active BWP RSSI is above or below the RSSI of a configured BWP, the number of NS indications in the active BWP is above a threshold, or the number of skipped RLM-RS transmissions is above a threshold.

[0169] The WTRU may be configured with multiple RSs contained in different subbands of a given BWP. The WTRU may select RSs from the subbands (e.g., the subband with the least interference) to perform RLM. For example, if competing nodes use unequal BWPs, different parts of the BWP may experience different interference.

[0170] The WTRU may be configured with a large set of RLM-RS. The WTRU may be configured to select a subset of the RLM-RS, for example based on some predefined rules.

[0171] The WTRU may select a subset of resources to monitor from a large set of configured resources. period_interval (For example, each T period_interval )A subset of resources is randomly selected to monitor. For example, if it is assumed that the spectrum occupancy from neighboring nodes and / or the CCA from the gNB follows a uniform distribution, the impact of interference can be randomized.

[0172] The configured RLM resources (e.g., each configured RLM resource or a configured set of RLM resources) may be associated with a specific monitoring period. The WTRU may be configured to monitor the resources (e.g., each resource) within a predefined time period. Diversity in link monitoring may be introduced. Not sending RS for a long time may not affect the reliability of the IS and / or OOS indication.

[0173] The presence of hidden nodes may be determined. The WTRU may be configured to perform CCA (e.g., measuring an RSSI threshold) in one or more predefined time windows (e.g., occurring at a preconfigured period). The WTRU may receive the results of a CCA performed by the network during the same predefined time window and / or period. The WTRU may receive the results in a broadcast message (e.g., SIB) or in dedicated RRC signaling. The WTRU may compare the results of local channel sensing (e.g., CCA at the WTRU) and remote channel sensing (e.g., CCA at the network). The WTRU may determine whether there are one or more hidden nodes based on the comparison. If the local CCA results and the remote CCA results do not match, the WTRU may determine that there are one or more hidden nodes. The WTRU may also be configured to trigger a report that indicates the presence of a hidden node to the network (e.g., when a mismatch occurs in the CCA results). The report may be sent via an RRC message or a measurement report. The WTRU may consider determining whether there are hidden nodes to perform channel state awareness RLM (e.g., as described herein).

Claims

1. A wireless transmit / receive unit (WTRU), the WTRU comprising: A processor configured to: Determine the maximum number of listen-before-talk (LBT) failures; performing a plurality of LBT procedures associated with a first bandwidth part (BWP) of a serving cell; determining that the first BWP for the serving cell has detected a number of LBT failures corresponding to the maximum number of LBT failures value; selecting a second BWP for the serving cell based on determining that the number of LBT failures corresponding to the maximum number of LBT failures value has been detected for the first BWP for the serving cell; performing an LBT procedure associated with the second BWP of the serving cell; Determining that the LBT procedure associated with the second BWP of the serving cell is successful; as well as A random access procedure associated with the second BWP of the serving cell is performed.

2. The WTRU of claim 1 , wherein the processor is further configured to send information to a base station indicating that a number of LBT failures corresponding to the determined maximum number of LBT failures value has been detected for the first BWP of the serving cell.

3. The WTRU of claim 1 , wherein the first BWP of the serving cell is active at a first time, a number of LBT failures associated with the first BWP of the serving cell is equal to or greater than a preconfigured value, and the second BWP of the serving cell is active at a second time, wherein the processor is further configured to determine that the number of LBT failures associated with the second BWP of the serving cell is less than the preconfigured value.

4. The WTRU of claim 3, wherein the serving cell comprises a plurality of BWPs, and the first BWP is an initial BWP among the plurality of BWPs and is inactive at the second time.

5. The WTRU of claim 1 , wherein the processor is configured to determine, based on a counter that counts the number of LBT failures associated with the first BWP of the serving cell, that the first BWP of the serving cell has detected the number of LBT failures corresponding to the maximum number of LBT failures value.

6. The WTRU of claim 5, wherein the processor is further configured to increment the counter based on an LBT failure in a number of LBT failures associated with the first BWP of the serving cell.

7. The WTRU of claim 1 , wherein the processor is configured to select the second BWP of the serving cell based on one or more characteristics of the second BWP.

8. The WTRU of claim 7, wherein the one or more characteristics of the second BWP include one or more of: quality of the second BWP, a channel state information reference signal (CSI-RS) measurement associated with the second BWP, channel availability of the second BWP, channel load of the second BWP, channel occupancy of the second BWP, a received signal strength indicator (RSSI) associated with the second BWP, a zero power reference signal (ZP-RS) measurement associated with the second BWP, and a predefined configuration.

9. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: Determine the maximum number of listen-before-talk (LBT) failures; performing a plurality of LBT procedures associated with a first bandwidth part (BWP) of a serving cell; determining that a number of LBT failures corresponding to the maximum number of LBT failures value has been detected for the first BWP of the serving cell; selecting a second BWP for the serving cell based on determining that the number of LBT failures corresponding to the maximum number of LBT failures value has been detected for the first BWP for the serving cell; performing an LBT procedure associated with the second BWP of the serving cell; Determining that the LBT procedure associated with the second BWP of the serving cell is successful; as well as A random access procedure associated with the second BWP of the serving cell is performed.

10. The method according to claim 9, further comprising: Information is sent to a base station, the information indicating that the number of LBT failures corresponding to the determined maximum number of LBT failures value has been detected for the first BWP of the serving cell.

11. The method according to claim 9, wherein: The first BWP of the service cell is active at a first time, the number of LBT failures associated with the first BWP of the service cell is equal to or greater than a preconfigured value, and the second BWP of the service cell is active at a second time, the method further comprising: determining that the number of LBT failures associated with the second BWP is less than the preconfigured value.

12. The method according to claim 11, wherein: The serving cell includes a plurality of BWPs, and the first BWP is an initial BWP among the plurality of BWPs and is inactive at the second time.

13. The method according to claim 9, wherein: Determining that the number of LBT failures corresponding to the maximum number of LBT failure values ​​has been detected for the first BWP of the serving cell is based on a counter that counts the number of LBT failures associated with the first BWP of the serving cell.

14. The method according to claim 13, further comprising: The counter is incremented based on an LBT failure in the number of LBT failures associated with the first BWP of the serving cell.

15. The method according to claim 9, wherein: The second BWP of the serving cell is selected based on one or more characteristics of the second BWP.

16. The method according to claim 15, wherein: The one or more characteristics of the second BWP include one or more of: quality of the second BWP, a channel state information reference signal (CSI-RS) measurement associated with the second BWP, channel availability of the second BWP, channel load of the second BWP, channel occupancy of the second BWP, a received signal strength indicator (RSSI) associated with the second BWP, a zero power reference signal (ZP-RS) measurement associated with the second BWP, and a predefined configuration.

17. A wireless transmit / receive unit (WTRU), the WTRU comprising: A processor configured to: Determine the maximum number of listen-before-talk (LBT) failures; performing a plurality of LBT procedures associated with a first bandwidth part (BWP) of a serving cell; determining a number of LBT failures that have occurred associated with the first BWP of the serving cell; determining that the number of LBT failures associated with the first BWP of the serving cell has reached the determined maximum number of LBT failures value; as well as Based on determining that the number of LBT failures associated with the first BWP of the serving cell has reached a determined maximum number of LBT failures value, a radio link failure (RLF) is declared.

18. The WTRU of claim 17 wherein the processor is configured to declare the RLF comprises: The processor is configured to send an indication to a higher layer that a RLF has occurred.

19. The WTRU of claim 17 wherein the processor is further configured to: selecting a second BWP for the serving cell based on the determined number of LBT failures associated with the first BWP for the serving cell reaching a determined maximum number of LBT failures; performing a plurality of LBT procedures associated with the second BWP of the serving cell; determining a number of LBT failures that have occurred associated with the second BWP of the serving cell; determining that the number of LBT failures associated with the second BWP of the serving cell has reached the determined maximum number of LBT failures value; as well as A radio link failure (RLF) is declared based on determining that the number of LBT failures associated with the second BWP of the serving cell has reached a determined maximum LBT failure number value and determining that the number of LBT failures associated with the first BWP of the serving cell has reached a determined maximum LBT failure number value.

20. The WTRU of claim 1, wherein the number of LBT failures associated with the first BWP of the serving cell is determined based on a timer.

21. A wireless transmit / receive unit (WTRU), the WTRU comprising a processor configured to: receiving one or more zero power reference signal (ZP-RS) configurations from a network; receiving a ZP-RS in one or more resource elements (REs) according to the received one or more ZP-RS configurations; measuring a power level in the RE; and Based on the measured power level being above a threshold, it is determined that a transmission instance of a radio link management reference signal (RLM-RS) is skipped.

22. A wireless transmit / receive unit (WTRU), the WTRU comprising a processor configured to: Receive instructions from the network as soon as possible; Based on the indication, determining that a transmission instance of a radio link management reference signal (RLM-RS) is skipped, wherein: The transmission instance of the RLM-RS occurs at a second time, and wherein the first time is after the second time; and Based on determining that the transmission instance of the RLM-RS is skipped, updating one or more of: an RLM criterion, an RLM procedure, or an RLM parameter set.

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