Method and apparatus for PUSCH repetition

Abstract

A method and apparatus are disclosed for performing a channel access procedure and transmitting a set of repetitions. A Wireless Transmit / Receive Unit (WTRU) may be configured to receive information for transmitting uplink data. The information may indicate a first number of nominal repetitions and a first number of symbols for each of the first number of nominal repetitions. The WTRU may be configured to determine a set of symbols associated with the first nominal repetition and transmit a second number of real repetitions in the symbols associated with the first nominal repetition. The second number of real repetitions and the symbols used to transmit the second number of real repetitions may be based on an occurrence of an event in the set of symbols associated with the first nominal repetition. The set of symbols associated with the first nominal repetition may comprise one or more subsets of consecutive uplink symbols.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 167,953, filed March 30, 2021, and U.S. Provisional Patent Application No. 63 / 185,576, filed May 7, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Different types of Physical Uplink Shared Channel (PUSCH) repetition are defined. Repetition type A allows a single repetition per slot. Extended repetition type A for 5G New Radio for unlicensed spectrum (NR-U) allows multiple repetitions per slot, but with a fixed mapping across all slots. Repetition type B allows sub-slot repetition by using nominal repetition. Multi-TTI scheduling has advantages such as reducing the amount of scheduling signaling. Furthermore, multi-TTI scheduling may reduce the need for Listen-Before-Talk (LBT) before every transmission if all PUSCHs are mapped to full slots. A method and apparatus are needed to enable sub-slot repetition in unlicensed environments and to enable multi-TTI scheduling with repetition. Summary of the Invention

[0003] A Wireless Transmit / Receive Unit (WTRU) may be configured to receive information for transmitting uplink data. The uplink data may be transmitted via a PUSCH. The information may indicate a first number of nominal repetitions and a first number of symbols for each of the first number of nominal repetitions. The WTRU may be configured to determine a set of symbols associated with the first nominal repetition. The WTRU may be configured to transmit a second number of real repetitions in symbols associated with the first nominal repetition. The second number of real repetitions and the symbols used to transmit the second number of real repetitions may be based on an occurrence of an event in the set of symbols associated with the first nominal repetition. The event may be at least one of a Channel Occupancy Time (COT) end, a channel access resource, a channel access procedure result, a Fixed Frame Period (FFP) idle period start time, or an FFP idle period end time. The set of symbols associated with the first nominal repetition may comprise one or more subsets of consecutive uplink symbols. At least one of the one or more subsets of consecutive uplink symbols may comprise at least two symbols. One subset of the one or more subsets of consecutive uplink symbols may not overlap with another subset of the one or more subsets of consecutive uplink symbols. Provided that an event occurs during a set of symbols associated with a first nominal repetition, the WTRU may be configured to transmit a first real repetition in one or more uplink symbols of the one or more subsets of consecutive uplink symbols before the occurrence of the event, and, provided that the channel access procedure is successful, transmit a second real repetition after the first real repetition transmission in one or more uplink symbols of the one or more subsets of consecutive uplink symbols after the occurrence of the event. The first real repetition may not be transmitted in a symbol after the event.The channel access procedure may be a Listen-Before-Talk (LBT) procedure. The channel access procedure may be based on at least one of a Channel Occupancy Time (COT) timing, an initiator of the COT, a Fixed Frame Period (FFP) timing, a previous channel access procedure result, whether a gap precedes the repetition, a size of the gap between the repetitions, or a cause of the gap between the repetitions. The actual repetition of the second number of actual repetitions may comprise at least one of a Configured Grant-Uplink Control Information (CG-UCI), a Demodulation Reference Signal (DM-RS), a Scheduling Request (SR), a Channel State Information (CSI), a Hybrid Automatic Repeat request (HARQ) Acknowledgement (ACK), or a Transport Block (TB). The WTRU may be configured to receive configuration information regarding resources for performing the channel access procedure. The resource may comprise at least one of a set of time instances, a set of frequency domains, or a beam.

[0004] The WTRU may be configured to determine when to perform a channel access procedure. The determination of when to perform a channel access procedure may be based on at least one of the number of repetitions, the size of the gap between repetitions, the cause of the gap between repetitions, frequency hopping, beam changing, channel occupancy time (COT) timing, whether the COT is user-initiated or network-initiated, fixed frame period (FFP) timing, or a previous channel access procedure result. The WTRU may be configured to receive an indication of an invalid set of resources. The invalid set of resources may not be used to transmit the set of repetitions. The indication may comprise information on a channel access type to use to resume transmission. The WTRU may be configured to receive a semi-static configuration of a channel access type to use to resume transmission. The indication of the invalid set of resources may be received in Downlink Control Information (DCI). The WTRU may be configured to receive configuration information regarding resources for performing the LBT. The resources may comprise at least one of a set of time instances, a set of frequency domains, or a beam. The repetitions may be associated with a set of possible start times. The WTRU may be configured to determine that the channel is idle and transmit a repetition at a first start time. The WTRU may be configured to determine that the channel is busy and perform a second LBT procedure before a second start time. The WTRU may be configured to send an indication of which LBT procedures were successful in transmitting the repetition. The WTRU may be configured to receive configuration information indicating a set of nominal repetitions, determine a set of symbols on which the nominal repetitions may be performed, and determine whether the set of symbols on which the nominal repetitions may be performed is valid. The determination of whether the set of symbols on which the nominal repetitions may be performed is valid may be based on at least one of whether an LBT is required before the repetition, a COT boundary timing, an FFP idle period timing, or a previous LBT result.The WTRU may be configured to segment a nominal repetition on condition that the nominal repetition includes one or more invalid symbols within the nominal repetition. The WTRU may be configured to determine an LBT type to use before the repetition. The determination of the LBT type to use may be based on at least one of a COT timing, a COT indicator, a COT status, a gap size, a cause of the gap, or whether the transmission is for a different TB than the preceding repeat transmission. The repeat transmission may include at least one of a CG-UCI, a DM-RS, a UCI, or a TB. The WTRU may be configured to skip, cancel, or postpone a repetition on condition that an LBT failure occurs. The WTRU may be configured to receive configuration information indicating resources on which to transmit multiple transport blocks. The WTRU may be configured to transmit all repetitions of a TB before transmitting a repetition of another TB. The WTRU may be configured to transmit all first repetitions of all TBs before transmitting a second repetition of the TB. The WTRU may be configured to receive configuration information regarding LBT bandwidth frequency hopping pattern information. The WTRU may be configured to perform frequency hopping between repeat transmissions. [Brief description of the drawings]

[0005] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numbers indicate similar elements and in which: [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1A is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A, according to one embodiment. [Figure 1C]FIG. 1B is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1D] FIG. 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Diagram 2] An example of repeat type A is shown below. [Diagram 3] An example of repeat type B is shown below. [Figure 4] An example of modified repeat type A is shown below. [Diagram 5] 1 shows an example of multi-TTI scheduling. [Figure 6] Here is an example of a COT that ends midway through a repetition. [Figure 7] An example of mapping nominal repetitions to real repetitions is given below. [Figure 8] Here is an example of an orphan symbol: [Figure 9] 1 illustrates an exemplary mapping of repetitions using multi-TTI scheduling. [Figure 10] 1 illustrates an exemplary mapping of repetitions using multi-TTI scheduling. [Figure 11] 1 illustrates an exemplary repeating cycle with a single transport block per slot. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] 1A illustrates an example 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, broadcasts, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communications 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 discrete Fourier transform Spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0007] 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. 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, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a station (STA), may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, mobile phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain context), consumer electronic devices, devices operating in commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0008] 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 wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an eNode B (eNB), a Home Node B, a Home eNode B, a next generation NodeB such as a gNode B (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, etc. Although the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0009] The base station 114a may be part of the RAN 104, which may also include other base stations, such as a base station controller (BSC), a radio network controller (RNC), relay nodes, and / or network elements (not shown). 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, which may be referred to as cells (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the 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., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell, for example, using beamforming to transmit and / or receive signals in a desired spatial direction.

[0010] 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, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0011] More specifically, as noted above, the communications system 100 may be a multiple access system and may use one or more channel access schemes, such as, for example, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a of the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). 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 ​​Uplink (UL) Packet Access (HSUPA).

[0012] In one 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 LTE-Advanced (LTE-Advanced, LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0013] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using NR.

[0014] In one 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 implement LTE radio access and NR radio access together, e.g., using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0015] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity, WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access, WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-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), GSM EDGE (GERAN), or the like.

[0016] 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as a location of a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.11, to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.15, to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 through the CN 106.

[0017] The RAN 104 may communicate with the CN 106, which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as, for example, different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 and / or the CN 106 may communicate directly or indirectly with other RANs that use the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA or WiFi radio technologies.

[0018] The CN 106 may also serve 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 public switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP Internet protocol suite. The networks 112 may include wired and / 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 that may use the same RAT as the RAN 104 or a different RAT.

[0019] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications 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). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may use a cellular-based wireless technology, and a base station 114b, which may use an IEEE 802 wireless technology.

[0020] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0021] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple 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), any other type of integrated circuit (IC), a state machine, etc. 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 FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0022] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0023] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0024] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0025] The processor 118 of the WTRU 102 may be coupled to and may receive user-entered data from a speaker / microphone 124, a 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). 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 data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), 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, etc. 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 home computer (not shown).

[0026] The processor 118 may receive power from the power source 134, but may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0027] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding a current location of the WTRU 102. In addition to or in lieu of information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of signals being received from two or more nearby base stations. It will be understood that the WTRU 102 may obtain location information by way of any suitable location determination method while remaining consistent with an embodiment.

[0028] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors. The sensor may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, and the like.

[0029] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals (e.g., associated with a particular subframe of both the UL (e.g., for transmission) and DL (e.g., for reception)) may be simultaneous and / or together. The full-duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference either through hardware (e.g., a choke) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio where transmission and reception of some or all of the signals (e.g., associated with a particular subframe of either the UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be simultaneous and / or together.

[0030] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As mentioned above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using E-UTRA radio technology. The RAN 104 may also communicate with the CN 106.

[0031] The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it will be understood 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 an embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0032] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG 1C, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0033] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are shown as part of the CN 106, it will be understood that any of these elements may also be owned and / or operated by an entity other than the CN operator.

[0034] 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 function as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. 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.

[0035] 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 perform other functions, such as anchoring the user plane during inter-eNode B handover, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0036] The SGW 164 may be connected to a PGW 166, 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.

[0037] 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 (e.g., an IP multimedia subsystem (IMS) server) that serves 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.

[0038] Although the WTRU is depicted in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use a wired communications interface (e.g., temporarily or permanently) with the communications network.

[0039] In an exemplary embodiment, the other network 112 may be a WLAN.

[0040] A WLAN in infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic within the BSS and / or outside the BSS. Traffic originating from outside the BSS to the STAs may arrive through the AP and be delivered to the STAs. Traffic originating from the STAs to destinations outside the BSS may be sent to the AP and transmitted to the respective destination. Traffic between STAs in the BSS may be transmitted, for example, through the AP, where the source STA may transmit traffic to the AP, which may deliver the traffic to the destination STA. Traffic between STAs in the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be transmitted in a direct link setup (DLS) between the source STA and the destination STA (e.g., directly between them). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may be referred to herein as an "ad-hoc" communication mode.

[0041] When using an 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be an operating channel of a BSS and may be used by STAs to establish a connection with an AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0042] A High Throughput (HT) STA may use a 40 MHz wide channel for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0043] A Very High Throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz and / or 80 MHz wide channels may be formed by combining multiple contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser that may split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing may be performed separately on each stream. The streams may be mapped to two 80 MHz channels and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed and the combined data may be transmitted to the Medium Access Control (MAC).

[0044] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter-type control / machine-type communications (MTC), such as MTC devices in macro coverage areas. MTC devices may have specific capabilities, including, for example, support for (e.g., support only for) specific and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0045] WLAN systems that may support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be configured and / or limited by the STAs among all STAs operating in the BSS that support the smallest bandwidth operating mode. In an 802.11ah example, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the state of the primary channel. For example, if the primary channel is busy, a STA (that only supports a 1 MHz mode of operation) transmitting to the AP may cause all of the available frequency bands to be considered busy, even if most of the available frequency bands are idle.

[0046] In the United States, the available frequency bands that can be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz depending on the country code.

[0047] 1D is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As mentioned above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using NR radio technology. The RAN 104 may also communicate with the CN 106.

[0048] The RAN 104 may include gNBs 180a, 180b, 180c, although it will be understood that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 108b may utilize beamforming to transmit and / or receive signals to the gNBs 180a, 180b, 180c. Thus, the gNB 180a may transmit wireless signals to and / or receive wireless signals from the WTRU 102a, for example, using multiple antennas. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, and the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or gNB 180c).

[0049] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless 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., including varying numbers of OFDM symbols and / or varying lengths of absolute time duration and varying times).

[0050] 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 another RAN (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate with and connect to a gNB 180a, 180b, 180c while also communicating with and connecting to another RAN, such as an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, while the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0051] 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, scheduling of users in UL and / or DL, support for network slicing, DC, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0052] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although the foregoing elements are shown as part of the CN 106, it will be understood that any of these elements may also be owned and / or operated by an entity other than the CN operator.

[0053] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for user authentication of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling different protocol data unit (PDU) sessions having different requirements), selection of a particular SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The network slicing may be used by the AMF 182a, 182b to customize the CN support of the WTRUs 102a, 102b, 102c based on the type of service utilizing the WTRUs 102a, 102b, 102c. For 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, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0054] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 106 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 106 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0055] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N3 interface, 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. The UPFs 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0056] The CN 106 may facilitate communication with other networks. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves 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. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to the local DNs 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0057] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0058] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation devices may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communication.

[0059] The one or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, for example, one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0060] The WTRU may determine the mapping of nominal to actual repetitions depending on the channel access procedure (eg, listen-before-talk (LBT)) timing and the channel occupation time (COT) or fixed frame period (FFP) configuration / timing.

[0061] The WTRU may determine the content and transmission parameters of a PUSCH repetition depending on at least one of the timing of the repetition, the timing of the associated LBT, the duration of the PUSCH repetition, the position of an adjacent PUSCH repetition, the timing of the COT, the result of a preceding LBT, the timing of an FFP idle period, the identity of the COT initiator, a previous drop of a transport block (TB), or a cancellation indication.

[0062] The WTRU may trigger repeated PUSCH transmissions until receipt of a Hybrid Automatic Repeat Request (HARQ)-ACK, until a timer expires, or until a new TB may be transmitted.

[0063] The WTRU may transmit multiple repetitions of a TB in a set of non-contiguous slots to allow multi-TTI scheduling with repetition.

[0064] Repetition can be used to improve the reliability of transmission without requiring the overhead of HARQ-ACK feedback. For Ultra-Reliable Low-Latency Communication (URLLC), two types of repetition are defined: Repetition Type A and Repetition Type B.

[0065] Figure 2 shows an example of repetition type A. In Figure 2, there are multiple slots separated by slot boundaries. A transmission repetition (e.g., a PUSCH transport block (TB)) may be transmitted once in each slot. Each slot may contain only one repetition, and the time domain for the repetition is the same in those slots. The Start and Length Indicator Value (SLIV) is the same for all slots.

[0066] Repetition type A may be a simple way to achieve repetition. However, for shorter allocations (i.e., sub-slot allocations), such repetition may not achieve optimal latency. It may be beneficial to allow sub-slot repetition. Figure 3 shows an example of repetition type B. In Figure 3, there are six symbols in each slot (which may be for uplink or downlink, as indicated by "U" or "D", respectively), and each slot is separated by a slot boundary. PUSCH transmissions may be repeated within a slot.

[0067] The nominal repetition may be defined for a particular time domain resource allocation (TDRA) / transport block size (TBS) combination. The WTRU may receive information regarding the nominal repetition. The WTRU may receive information indicating the number of nominal repetitions and the number of symbols for which the PUSCH transmission may be repeated in the nominal repetition. The nominal repetition may be interrupted, for example, by a DL symbol or slot boundary. The nominal repetition may be divided into real repetitions such that each real repetition is not interrupted by a DL symbol or slot boundary. Thus, in a repetition scheme with K nominal repetitions, there may be more than K real repetitions. For example, in FIG. 3, K=4 and the nominal repetition is 4 symbols. In this case, there are 5 real repetitions.

[0068] Repetition type A may be modified to allow multiple repetitions within a slot. Figure 4 shows a modification of repetition type A with two repetitions within a slot. This may, for example, reduce the required number of LBTs required for a set of repetitions. However, each slot has the same number of repetitions and their positions are fixed within the slot.

[0069] Multi-TTI scheduling may reduce the signaling required for multiple uplink grants. In multi-TTI scheduling, a new TB is transmitted in a set of slots. Figure 5 shows an example of multi-TTI scheduling in which new (i.e., different) TBs (e.g., TB1-TB6) are transmitted in slots 1-6, respectively.

[0070] Repetition (e.g., PUSCH repetition) may be advantageous to improve robustness in unlicensed spectrum. Sub-slot repetition for unlicensed spectrum may have limitations such that each slot may have similar resource mapping. However, this scheme does not handle dynamic TDD slot formats well and is not flexible for different PUSCH allocation sizes. Repetition type B may have advantages, but was not specified with unlicensed spectrum in mind. Therefore, a method is needed to enable repetition type B in unlicensed spectrum to handle the effects of LBT, COT, and FFP time.

[0071] Multi-TTI scheduling can be beneficial since it reduces the need for signaling, however, methods are needed to enable multi-TTI scheduling with repetition that can allow reduced signaling overhead in combination with robust, low-latency transmission.

[0072] The WTRU may be configured to perform a set of repetitions (e.g., repetitions for TB). The WTRU may use a channel access procedure (e.g., LBT) before at least one repetition. The channel access procedure or LBT may be used interchangeably herein.

[0073] The WTRU may determine when to perform the LBT based on the number of iterations. In one example, the WTRU may perform the LBT before a particular iteration (e.g., the first iteration). In one example, the WTRU may perform the LBT before every iteration. In one example, the WTRU may perform the LBT before every n-th iteration, where n may be configurable.

[0074] The WTRU may determine when to perform the LBT based on the gap preceding the repetition. For example, if two consecutive repetitions are transmitted in adjacent symbols, the WTRU may not perform the LBT before the second repetition. If two repetitions have a gap between them, the WTRU may perform the LBT before the second repetition.

[0075] The WTRU may determine when to perform the LBT based on the size of the gap between the repetitions. For example, the WTRU may perform the LBT before the second repetition if the gap between two consecutive repetitions is larger than a value x. The value x may be configurable.

[0076] The WTRU may determine when to perform the LBT based on the cause or purpose of the gap between successive repetitions. For example, the WTRU may perform the LBT before the second repetition depending on the cause of the gap between the first and second successive repetitions. The cause of the gap may include, for example, at least one of a DL symbol, a flexible symbol dynamically or semi-statically switched to DL, an orphaned UL symbol, an idle period in a fixed frame period (FFP), a canceled transmission (e.g., by instruction via UL CI), a change in COT parameters, or a dropped transmission due to a failed LBT.

[0077] The WTRU may determine when to perform the LBT based on frequency hopping, for example, if frequency hopping is used between successive iterations, the WTRU may perform the LBT before the first iteration after the frequency hop.

[0078] The WTRU may determine when to perform the LBT based on the beam change, for example, if the transmission beam is changed between successive iterations, the WTRU may perform the LBT before the first iteration that occurs after the beam change.

[0079] The WTRU may determine when to perform the LBT based on the COT timing. For example, if successive repetitions are transmitted at different COTs, the WTRU may perform the LBT before the second repetition and start a new COT. In one example, if the resource of a repetition overlaps with the end of a COT, the WTRU may perform the LBT before the repetition transmission and start a new COT.

[0080] The WTRU may determine when to perform the LBT depending on who initiated the COT. For example, if the repetition is transmitted in a COT initiated by the WTRU, the WTRU may determine a first set of LBT opportunities. If the repetition is transmitted in a COT initiated by the gNB, the WTRU may determine a second set of LBT opportunities.

[0081] The WTRU may determine when to perform the LBT based on the FFP timing, for example, if successive repetitions are transmitted in different FFPs, the WTRU may perform the LBT before the second repetition.

[0082] The WTRU may determine when to perform an LBT based on previous LBT results. For example, the WTRU may perform an LBT before an iteration if the LBT failed before the previous iteration. In one example, the WTRU may perform an LBT before an iteration based on the quantitative performance of the LBT for the previous iteration. For example, the WTRU may have a first energy detection threshold for determining whether it may transmit. The WTRU may also maintain an energy detection measurement and may determine, based on the absolute value (or compared to a second energy detection threshold), whether an LBT is required before a subsequent iteration transmission.

[0083] A WTRU may receive an indication that a resource (e.g., a time or frequency unit or beam) may not be used for repeated transmissions. Such resources may be considered dynamically indicated invalid resources. The indication may inform the WTRU of the set of invalid resources as well as the type of channel access required to resume transmission after occurrence of such invalid resources. For example, a WTRU may receive an indication that a first resource may not be used for repeated transmissions. Not transmitting on such resources may lead to a gap (e.g., a new gap or an extension of an already existing gap). The WTRU may determine the type of channel access (e.g., whether to use LBT, the type of LBT, parameters associated with LBT) from the indication. In one embodiment, the WTRU may be configured (e.g., semi-statically configured) with or receive information regarding the behavior to use to access the channel after such dynamic invalid resources are configured.

[0084] The WTRU may receive an indication of disabled resources or associated channel access in a DCI (e.g., a DCI scheduling a set of repetitions). The indication may explicitly indicate the set of resources for which repetitive transmissions are disabled. In one embodiment, the indication may be a bit field that maps to a configurable set of disabled resources or channel access type patterns.

[0085] The WTRU may be configured with or receive information on a set of resources (e.g., time instances or frequency regions or beams) for when to perform the LBT. When the WTRU is transmitting a set of repetitions, the WTRU may determine that any one resource in the set of configured resources for when to perform the LBT should be considered as an invalid symbol for the repetition transmission. The WTRU may perform the LBT using one of the resources in the set of configured resources to obtain an unlicensed channel for one or more repetition transmissions. For example, the WTRU may select a resource from the set of configured resources to perform the LBT if such resource occurs before a real or nominal repetition (e.g., in the previous symbol). The WTRU may perform the LBT on one resource from the set of resources, for example, if there is no ongoing COT.

[0086] The WTRU may be configured with a set of nominal repetitions. The WTRU may determine the set of symbols in which each nominal repetition may occur.

[0087] The WTRU may determine whether a set of symbols of a nominal repetition is valid depending on whether an LBT is required before the repetition. For example, if an LBT is required before a repeat transmission, the first n symbols of the repetition may be reserved for the LBT. In one example, if an LBT is required before a repeat transmission, the last n symbols of the previous repetition may be reserved for the LBT.

[0088] The WTRU may determine whether a set of symbols of a nominal repetition is valid depending on the COT boundary timing. For example, if the COT ends on one of the symbols of the repetition, the WTRU may not transmit on the set of n subsequent symbols in the repetition. In another example, if the COT ends on a symbol preceding a repetition, based on the time of the COT end, the WTRU may determine a set of m symbols at the beginning of the subsequent repetition that may not be used for the repetition transmission.

[0089] The WTRU may determine whether a set of symbols for a nominal repetition is valid depending on the FFP idle period timing. For example, if an FFP idle period occurs during a repetition, the symbols that overlap with the idle period may not be used for that repetition transmission.

[0090] The WTRU may determine whether the set of symbols for the nominal repetition is valid depending on the previous LBT result. For example, based on the result of the LBT for the previous repetition, the WTRU may determine the set of symbols that may be used for the subsequent repetition transmission.

[0091] When a nominal repetition has one or more invalid symbols occurring during the nominal repetition, the WTRU may split or segment the repetition into multiple real repetitions. Each real repetition may be the entire transmission of a TB (e.g., using rate matching) or a segment of a TB. All segments of a TB may be transmitted in a set of real repetitions that comprise the nominal repetition.

[0092] FIG. 6 shows an example of a COT that ends during a repetition. After the COT ends, the WTRU may restart the COT and continue to transmit the repetition using n symbols (n=1 in FIG. 6) for the LBT. For the repetition where the COT ends (i.e., nominal repetition 3 in FIG. 6), the WTRU may use two real repetitions for the nominal repetition. In an embodiment, the WTRU may segment the repetition into two parts and transmit the first part in a first COT and the second part in a second COT.

[0093] The WTRU may split a nominal repetition into multiple real repetitions depending on the COT timing or the FFP idle period timing. The WTRU may segment a nominal repetition into multiple segments depending on the COT timing or the idle period timing. For example, if the COT ends during a nominal repetition or an FFP idle period occurs during a repetition, the WTRU may split the nominal repetition and transmit two real repetitions (e.g., a copy of a TB each) in two sets of adjacent uninterrupted resources. The two sets of adjacent resources may be separated by the COT boundary timing or the FFP idle period timing, and may be separated by resources used to perform an LBT before the second repetition.

[0094] FIG. 7 illustrates an example method (700) for mapping nominal repetitions to real repetitions. The WTRU may receive information regarding a configuration of nominal repetitions (710). The information may indicate a number of nominal repetitions. The information may indicate a number of symbols to use for each nominal repetition. The WTRU may determine a set of symbols associated with a nominal repetition (e.g., a first nominal repetition) (720). The WTRU may determine the set of symbols associated with a nominal repetition depending on at least one of the following: a starting symbol of one of the nominal repetitions (e.g., the first nominal repetition), a total number of repetitions, a number of symbols per repetition, a number of repetitions (e.g., whether the nominal repetition is the first or second or third, etc.), a SLIV received in the UL grant (e.g., in a DCI or RRC configuration), the SCS of the repetition, whether frequency hopping is used, a COT configuration, or a COT initiator (e.g., WTRU-initiated COT or gNB-initiated COT). The WTRU may transmit a number of real repetitions (730). The number of real repetitions may be greater than the number of nominal repetitions. The real repetitions may be transmitted in one or more symbols (e.g., consecutive symbols) associated with the nominal repetition. The real repetition transmission may be based on the occurrence of an event in a set of symbols associated with the nominal repetition. The event may be, for example, a COT end, a channel access resource, a channel access procedure result, an FFP idle period start time, or an FFP idle period end time. The set of symbols associated with the nominal repetition may comprise one or more subsets of consecutive uplink symbols. The subset of consecutive uplink symbols may comprise at least two symbols. One subset of consecutive uplink symbols may not overlap with another subset of consecutive uplink symbols. The WTRU may transmit a real repetition (e.g., a first real repetition) in an uplink symbol of the subset of consecutive uplink symbols prior to the occurrence of the event. The WTRU may perform a channel access procedure (e.g., an LBT).If the channel access procedure is successful, the WTRU may transmit another virtual repetition (e.g., a second virtual repetition) after the first virtual repetition transmission in uplink symbols of a subset of consecutive uplink symbols after the occurrence of the event. If the channel access procedure fails. The WTRU may perform the second channel access procedure in the next symbol. If the second channel access procedure is successful, the WTRU may transmit another virtual repetition after the first virtual repetition transmission in uplink symbols of a subset of consecutive uplink symbols after the occurrence of the event. If the second channel access procedure fails, the WTRU may continue to perform the channel access procedure until successful and then transmit a virtual repetition.

[0095] The WTRU may perform an LBT before at least one repeat transmission. In an embodiment, the WTRU may determine that the channel is busy and may not transmit at least one subsequent transmission (e.g., a repetition). Each nominal or real repetition may be associated with a set of possible start times. If the WTRU does not need to perform an LBT before the first start time of a repetition, the WTRU may transmit the repetition using the first start time. If the WTRU needs to perform an LBT before transmitting a repetition, the WTRU may perform a first LBT procedure before the first start time. If it is determined based on the first LBT procedure that the channel is idle and available for transmission, the WTRU may transmit a repetition starting at the first start time. If it is determined based on the first LBT procedure that the channel is busy, the WTRU may perform a second LBT procedure before the second start time. If it is determined based on the second LBT procedure that the channel is idle and available for transmission, the WTRU may transmit a repetition starting at the second start time. If the channel is determined to be busy based on the second LBT procedure, the WTRU may perform a third LBT procedure before the third start time. The WTRU may continue to perform additional LBTs if the channel is determined to be busy based on the current LBT.

[0096] The WTRU may indicate which LBT procedures were successful in the iteration transmission. An indication may be provided to the network (e.g., gNB). For example, the indication may be provided in the CG-UCI of the iteration or a subsequent iteration.

[0097] The WTRU may use frequency hopping between repetitions. Frequency hopping may ensure that the WTRU has repetitions scheduled for different LBT bandwidths (BWs) or channels, which may increase the channel access probability. The WTRU may be configured with or receive configuration information about an LBT BW hopping pattern. Such configuration may be semi-static or dynamic. For example, the WTRU may receive configuration information in a DCI that schedules a set of repetitions.

[0098] The WTRU may determine a set of invalid symbols associated with the frequency hop. For example, the invalid symbols may affect the mapping of the first iteration transmitted after (e.g., immediately after) the frequency hop. Such a set of invalid symbols may be used by the WTRU to perform the LBT in the new LBT BW.

[0099] The WTRU may perform LBT after a frequency hop if the hop moves transmission to a frequency region that is within the new LBT BW (i.e., compared to the frequency region of the previous hop).

[0100] The WTRU may perform an LBT before a set of repetitions, and such an LBT procedure may be applicable to transmissions of a subsequent set of repetitions.

[0101] A WTRU performing LBT on a previous repetition set may perform LBT on at least one of an LBT BW covering resources of a next repetition or an LBT BW covering resources of all repetitions in the repetition set.

[0102] In one embodiment, the WTRU may perform an LBT over the LBT BW of the set of repetitions before the transmission of the set of repetitions. The WTRU may not need to perform an LBT at each frequency hop. In one embodiment, the WTRU may perform a first LBT of a first LBT type (e.g., LBT Type 4 or full LBT) over the LBT BW of the set of repetitions before the transmission of the set of repetitions, and perform a second LBT of a second LBT type (e.g., LBT Type 2 or short LBT) only over the LBT BW of the transmission made at or after each frequency hop.

[0103] A WTRU may be configured with multiple LBT types, each of which may have different channel assessment parameters (e.g., energy detection threshold, contention window size, clear channel assessment slot duration, etc.).

[0104] The WTRU may determine an LBT type to use before a nominal or actual repeat transmission with COT timing. For example, the WTRU may perform a first type of LBT (e.g., LBT type 4) before a repeat if the COT ends before the repeat timing or during the repeat timing. In an embodiment, the WTRU may determine the type or configuration of the LBT based on the time the current COT started (type may include no LBT). For example, the WTRU may determine the type or configuration of the LBT based on whether the current COT started before the repeat set or during the transmission of the repeat set.

[0105] The WTRU may determine the LBT type to use prior to a nominal or real repeat transmission by a COT initiator. For example, the WTRU may determine the type of LBT depending on the node that originally initiated the COT where the repeat is transmitted.

[0106] The WTRU may determine an LBT type to use before a nominal or actual repeat transmission depending on the COT status. For example, the WTRU may perform an LBT of a first type or configuration if there is an ongoing COT (type may include no LBT) and may perform an LBT of a second type or configuration if there is no ongoing COT and a COT needs to be initiated.

[0107] The WTRU may determine the LBT type to use before transmitting a nominal or real repeat depending on the gap size. For example, the WTRU may determine the type of LBT to use before transmitting a repetition depending on the gap size between that repetition and the previous repetition.

[0108] The WTRU may determine the LBT type to use before transmitting a nominal or real repeat due to the cause of the gap. For example, the WTRU may determine the type of LBT to use before transmitting a repetition depending on the cause of the gap between that repetition and the previous repetition. The cause of the gap may include a DL symbol, a flexible symbol dynamically or semi-statically switched to DL, an orphan UL symbol, an idle period in a fixed frame period (FFP), a canceled transmission (e.g., by instruction via UL CI), a change in COT parameters, or a dropped transmission due to a failed LBT.

[0109] The WTRU may determine the LBT type to use before a nominal or real repeat transmission depending on whether the transmission is for a different TB than the preceding (e.g., immediately preceding) repeat transmission. For example, the WTRU may transmit multiple TBs. Each TB may have multiple repetitions. The WTRU may determine the LBT type if two consecutive repetitions are for the same or different TBs.

[0110] The WTRU may determine the content to include in the repetition (i.e., nominal repetition or real repetition). In a repetition transmission, the WTRU may include, for example, at least one of the following elements: CG-UCI, demodulation reference signal (DM-RS), UCI (e.g., Scheduling Request (SR), Channel State Information (CSI), HARQ-ACK, or TB.

[0111] The WTRU may determine which content to include in the repeated transmission based on the number of repetitions. For example, the WTRU may include CG-UCI in the first repetition (e.g., only in the first repetition). In one example, the WTRU may include CG-UCI or UCI in the nth repetition or every mth repetition.

[0112] The WTRU may determine which content to include in a repetition transmission based on the repetition size. For example, the WTRU may include CG-UCI if the repetition duration is greater than a value x. The value of x may be fixed or may depend on the nominal repetition size. For example, if the nominal repetition is of size n and due to invalid resources the actual repetition is of size m, the UE may include CG-UCI if m>nk, where k may be configurable or fixed.

[0113] The WTRU may determine which content to include in a repeat transmission based on whether the repetition is split or segmented. For example, the WTRU may include the CG-UCI or DM-RS or UCI once per nominal repetition. If the nominal repetition is split or segmented into multiple real repetitions, the WTRU may transmit the CG-UCI or DM-RS or UCI in a single real repetition. The WTRU may determine the real repetition that includes the CG-UCI or DM-RS or UCI to be the y-th (e.g., first or last) repetition. The WTRU may determine the real repetition that includes the CG-UCI or DM-RS or UCI to be the real repetition that has a duration greater than a value x.

[0114] The WTRU may determine which content to include in a repeat transmission based on whether the repetition was preceded by an LBT (e.g., immediately preceded). For example, the WTRU may include the CG-UCI if it performed an LBT procedure before the repetition (e.g., after the immediately preceding repetition).

[0115] The WTRU may determine which content to include in a repeat transmission based on the COT timing, for example, the WTRU may include CG-UCI in a repeat if a new COT was started before the repeat transmission or in the time between the repeat and a preceding repetition (e.g., the immediately preceding repetition).

[0116] The WTRU may determine which content to include in a repeated transmission based on the number of repetitions in a slot. For example, the WTRU may include CG-UCI or DM-RS or UCI in a single repetition in a slot. The WTRU may include CG-UCI or DM-RS or UCI in the first repetition of the slot.

[0117] The WTRU may determine which content to include in the repeat transmission based on the HARQ process ID. For example, the WTRU may include the CG-UCI if the HARQ process ID of the TB has changed from the previous repeat transmission.

[0118] The WTRU may determine which content to include in the repeated transmission based on the priority of the transmission. For example, the WTRU may determine whether to include CG-UCI or UCI depending on the priority of UCI or TB.

[0119] The WTRU may determine which content to include in a repeat transmission based on a previously dropped transmission. For example, if the CG-UCI was dropped from a previous repetition, it may be included in a subsequent repetition. In one example, if a previous transmission was dropped (e.g., due to a failed LBT of reception of the UL CI), the WTRU may include the CG-UCI in a subsequent repeat transmission.

[0120] The WTRU may determine which content to include in a repeated transmission based on whether rate matching is used on the TB.

[0121] The WTRU may determine what content to include in a repeat transmission based on whether the frequency or beam has changed. For example, the WTRU may include CG-UCI if the repeat is transmitted after frequency hopping or after a change in transmission beam.

[0122] The WTRU may determine which elements to include in a repetitive transmission depending on a number of transmission criteria described herein. As an example, if the priority of the TB is high (e.g., greater than a threshold or configured value), the WTRU may determine that the CG-UCI may be included in every repetition. In one example, if the priority of the UCI is high (e.g., greater than a threshold or configured value), the WTRU may include the UCI in a first set of repetitions, and if the priority of the UCI is low (e.g., less than a threshold or configured value), the WTRU may include the UCI in a second set of repetitions.

[0123] The WTRU may drop an element from a repetition and include another element. For example, the WTRU may drop the CG-UCI and transmit only the UCI with the TB if the UCI is of high priority (e.g., greater than a threshold or configured value). When an element is dropped to allow transmission of another (e.g., higher priority) element, the WTRU may include the dropped element in a subsequent repetition.

[0124] The CG-UCI may be transmitted in multiple repetitions of the set of repetitions. The content of the CG-UCI may remain the same for each repetition. In one example, if the CG-UCI is transmitted in more than one repetition, the CG-UCI content may change for each CG-UCI transmission. For example, the first CG-UCI in the set of repetitions may include the required information (e.g., all required information) and any subsequent CG-UCI in the set of repetitions may include only changes or updates to the CG-UCI. In one example, the first CG-UCI in the set of repetitions may include the required information (e.g., all required information) and subsequent CG-UCIs may include only information related to that repetition. For example, if the HARQ process ID may change for each repetition, the CG-UCI may include the HARQ process ID related to the associated repetition, but any other content that is fixed for all repetitions may be transmitted by the WTRU only once for each set of repetitions.

[0125] The content of the CG-UCI may be determined by rules similar to those described herein for determining whether to include CG-UCI. For example, the content of the CG-UCI may depend on the size of the real repeat and may be related to the size of the nominal repeat.

[0126] The content of a CG-UCI may depend on whether it is multiplexed with other UCIs. The content of a CG-UCI that is multiplexed with other UCIs may depend on the priority of the CG-UCI or the TB, or the priority of the other UCIs.

[0127] The content of the CG-UCI may include at least one of the following: HARQ process ID, repetition number, priority (e.g., priority of transmission or priority of LBT used before transmission), redundancy version (RV), Modulation and Coding Scheme (MCS), beam ID, nominal repetition duration, and DMRS mapping type.

[0128] An orphan symbol may occur when a nominal repetition is split or segmented into multiple possible real repetitions, where one such possible real repetition is a single symbol. The split or segmentation may be caused by at least one of a DL symbol, a slot boundary, a COT timing, or an FFP idle period timing.

[0129] The WTRU may transmit one or more elements of a repetition using an orphan symbol. This may be beneficial to reduce the need for LBT caused by unused orphan symbol gaps. In one example, the WTRU may transmit a CG-UCI or a DM-RS in an orphan symbol. In such a case, the WTRU may not need to transmit a CG-UCI or a DM-RS in one or more associated real repetitions.

[0130] The WTRU may determine whether to transmit on or what elements to transmit within an orphan symbol based on the transmission criteria described herein.

[0131] An orphan symbol may be associated with a real repeat based on whether both the orphan symbol and the real repeat are within the same nominal repeat.

[0132] An orphan symbol may be associated with a virtual repetition based on the timing of the orphan symbol. For example, an orphan symbol may be associated with a preceding virtual repetition. In another example, an orphan symbol may be associated with a subsequent virtual repetition.

[0133] An orphan symbol may be associated with a virtual repetition based on the duration of the virtual repetition. For example, an orphan symbol may be associated with a virtual repetition if it is of duration less than a value x or greater than a value y.

[0134] An orphan symbol may be associated with a real repetition based on slot timing, e.g., if the orphan symbol and the real transmission are in the same slot, the orphan symbol may be associated with the real transmission.

[0135] The orphan symbol may be associated with a virtual repetition based on the COT status. For example, the WTRU may decide to transmit on the orphan symbol if there is an ongoing COT or if there is no ongoing COT.

[0136] The orphan symbol may be associated with a substantial repetition based on the COT indicator. For example, the WTRU may decide to transmit on the orphan symbol depending on which node (e.g., the WTRU or the gNB) has initiated the ongoing COT. For example, if the gNB or another WTRU has initiated the COT, the WTRU may not transmit on the orphan symbol. If the WTRU has initiated the COT, the WTRU may transmit on the orphan symbol.

[0137] The WTRU may determine whether to use an orphan symbol to transmit an element depending on gaps that may be created if the orphan symbol is not used. For example, if not transmitting on an orphan symbol creates a gap between repetitions that is greater than a value x (e.g., a gap that requires an LBT before the next repetition transmission), the WTRU may transmit one or more elements on the orphan symbol. The WTRU may determine whether to use an orphan symbol for a transmission based on whether two orphan symbols are adjacent. For example, if two orphan symbols are adjacent, the WTRU may transmit on at least one of the orphan symbols.

[0138] FIG. 8 shows an example of two adjacent orphan symbols, both occurring in nominal repetition 2. In this case, the WTRU may determine that the gap created by one or more adjacent orphan symbols is larger than a threshold. The threshold may be configured or fixed, or the WTRU may receive an indication of the threshold. The indication may be received, for example, via a DCI, MAC, or RRC configuration. The WTRU may transmit a repetition element (e.g., CG-UCI, DM-RS, UCI, or TB) in at least one of the orphan symbols. This may be beneficial to maintain the COT and reduce the need for an LBT before transmitting the remainder of nominal repetition 2.

[0139] The WTRU may transmit UCI in the orphan symbol. The WTRU may transmit UCI on the PUSCH in the orphan symbol. In one embodiment, the WTRU may transmit UCI on a physical uplink control channel (PUCCH) if configured with PUCCH resources in the orphan symbol. In such a case, subsequent repetitions in the nominal repetition (e.g., the associated repetition) may include UCI on the PUSCH or may not include UCI at all.

[0140] The WTRU may transmit DM-RS on the orphan symbol if it is configured for cross-repetition or cross-slot DM-RS.

[0141] The WTRU may transmit a number of symbols greater than the number of symbols in the nominal repetition to keep the channel occupied. The WTRU may transmit more actual repetitions than the number required (e.g., a configured number) to maintain the COT. The WTRU may determine that another new TB is arriving within a certain time before the expiration of the current COT occupied by the WTRU. The WTRU may transmit additional repetitions and / or symbols of the current TB to keep the channel occupied until the next TB arrives in the WTRU buffer and / or can be transmitted. The WTRU may determine the TB arrival based on a configured traffic pattern. In one example, the WTRU may already have bits buffered for transmission on the new TB, but transmitting a nominal repetition for the new TB may require waiting for another UL slot or a different PUSCH opportunity (e.g., after a DL interruption), or the number of UL symbols and / or slots remaining before the DL interruption does not allow the WTRU to transmit the new TB. The WTRU may transmit additional symbols and / or repetitions of the current TB, even if it exceeds the configured number of required repetitions and / or symbols in the nominal repetitions, to keep the channel occupied until the DL interruption time, until the next FFP IDLE period, until the COT can be shared with the gNB, until a stop indication is received from the gNB, or until the WTRU can access an uplink slot that can possibly be used to transmit new data on the same HARQ process.

[0142] The WTRU may repeat the TB until a time (e.g., a CG timer) expires, or until it is determined that x time has elapsed for the HARQ process, or until receiving a HARQ-ACK equals an ACK on the Downlink Feedback Information (DFI). In one example, the WTRU may continue to occupy the channel with a transmission from a different HARQ process y until it determines that the CG retransmission time has elapsed (e.g., the CG retransmission timer expires) for the pending HARQ process x. This may allow the WTRU to immediately retransmit the TB and / or a repetition of HARQ process x after determining that the CG retransmission time has elapsed (e.g., upon expiration of the CG retransmission timer).

[0143] The WTRU may repeat the transmission up to a configured number of repetitions (e.g., rep K) or until the next downlink slot or downlink symbol. The WTRU may receive an indication from the Downlink Control Information (DCI) or Radio Resource Control (RRC) indicating a configured grant that the WTRU may transmit repetitions until it encounters the next downlink. This may be useful to maintain a burst of repeat transmissions until the next downlink slot, or until an idle period, or until the COT can be released or shared with the gNB.

[0144] The WTRU may multiplex UCI on an uplink channel (e.g., CG-UCI on a PUSCH) that is transmitting additional symbols and / or additional repetitions (e.g., to maintain the COT or until the end of the COT). The UCI may comprise the number of additional symbols or additional repetitions in the current COT or relative to the bundle size.

[0145] In one embodiment, the gNB may inform the WTRU of a dynamic number of repetitions and / or symbols to be used for transmitting real repetitions during a UL transmission opportunity following a DL, possibly in a shared COT. For example, in a scenario where TDD split in slots or frames is configured as DUUUU-DUUUU, even if the nominal repetition is three symbols (or slots), the WTRU may transmit a real repetition of four symbols to ensure that the COT is maintained until the next DL symbol or slot, the next FFP or idle period, or until the indicated amount of uplink symbols or slots has elapsed. The WTRU may transmit additional symbols of real repetitions upon receiving an indication from the gNB, where the number of symbols may be greater than the nominal repetitions. The WTRU may transmit additional repetitions upon receiving an indication from the gNB, where the number of repetitions may be greater than the configured number of repetitions. The indication from the gNB may indicate the number of symbols applicable for the remaining repetition(s), the number of symbols applicable for the remaining repetition(s) in the current / shared COT, the number of additional repetitions, or the number of additional repetitions in the current / shared COT.

[0146] The WTRU may transmit a smaller number of UL symbols in the actual repetition than the number of symbols in the nominal repetition. For example, the WTRU may transmit on some symbols or orphan symbols to maintain the COT. The WTRU may be configured with a minimum number of symbols. Configuration may be by higher layers. If the number of symbols in the actual repetition is less than the minimum number of symbols, the WTRU may transmit the repetition but not count it towards the configured target number of repetitions, or the WTRU may not transmit the repetition at all.

[0147] The WTRU may postpone, skip, or cancel a repetition if it encounters a UL LBT failure. The WTRU may increment a repetition count if a repetition is transmitted.

[0148] When a WTRU experiences an UL LBT failure for a repetition, receives a cancel indication, or drops a repetition due to, for example, inter-WTRU / intra-WTRU prioritization, the WTRU may continue the remaining repetitions when it encounters the next transmission opportunity, or terminate the remaining repetition transmission. The WTRU may drop, skip, delay, or cancel a repetition. The WTRU may continue transmitting a repetition if the repetition count falls below a predefined threshold, if the channel is acquired again, and / or if the number of UL symbols per previously transmitted repetition(s) was equal to the nominal repetition. The WTRU may be configured with a predefined threshold, for example, by the RRC, the MAC control element (MAC-CE), or DCI.

[0149] The WTRU may receive DCI MAC CE or RRC signaling indicating resumption of remaining repetition transmission and / or a configured grant under which the WTRU may continue the remaining repetitions. The WTRU may receive DCI or RRC indicating a HARQ ID that the WTRU may use to transmit the remaining repetitions. The WTRU may receive an explicit instruction from the gNB to suspend or cancel the remaining repetitions while waiting for the next uplink slot to complete the specified number of repetitions. The WTRU may cancel or pause repetitions, possibly before the repetition count reaches a configured number of repetitions (e.g., rep K) for a given HARQ process. For example, the WTRU may receive a dynamic notification in the DCI or MAC-CE, possibly in a different COT than that used to transmit the initial set of repetitions, to terminate or pause repetitions in a downlink slot from the network. The WTRU may cancel the remaining repetitions if they were dropped due to network signaling (e.g., due to receiving a cancellation indication from the gNB), but cannot cancel them if they were dropped due to an LBT failure or intra-WTRU prioritization, and the gNB may not know that they were dropped / not transmitted.

[0150] The WTRU may transmit unsuccessful LBT repetitions (e.g., based on the number of failed LBTs or the number of LBT failures counted, such as at the MAC layer) using a different LBT configuration (e.g., Channel Access Priority Class (CAPC), LBT category, or modified LBT parameters).

[0151] The WTRU may change the number of UL symbols and / or slots used to transmit the actual repetitions after acquiring another COT for transmitting the remaining repetitions. The change may be based, for example, on the available number of UL slots and / or symbols in the new COT and the available UL resource allocation (e.g., the configuration of the CG in the new COT and / or the allocation of dynamic grants provided in the new COT). The WTRU may include in the UCI (e.g., CG-UCI) multiplexed on the PUSCH indicating the HARQ process, TB index, and / or RV of the applicable repetitions. The WTRU may skip incrementing the RV number upon failure of the LBT for a repetition in the sequence. The WTRU may indicate in the UCI that a subset of past repetitions was dropped due to LBT failure or intra-WTRU priority decrement (e.g., to aid soft combining). For example, the WTRU may indicate that a previous set of repetitions was dropped in the CG-UCI transmitted in the first subsequent repetition after the dropped set of repetitions. The indication may include the identity or number of the previous repetitions that were dropped. The indication may be included in multiple subsequent CG-UCIs (e.g., for robustness). A bitmap may be included in the CG-UCI to flag the set of repetitions that were dropped.

[0152] A UL LBT failure counter or indicator may be maintained for each iteration, or for each set of iterations, or for each LBT attempt. For example, the UL LBT failure may be incremented by one each time an LBT fails, or by the number of iterations (e.g., real or nominal) that were dropped due to LBT failure. If a iteration has multiple start times, the UL LBT failure counter may be incremented if none of the iteration start times were considered valid due to all LBTs failing. If a nominal iteration is segmented into multiple real iterations, the UL LBT failure counter may be incremented for each failure to transmit a real iteration, or if all real iterations have failed.

[0153] The WTRU may be restricted to transmit repetitions (e.g., Type A or Type B) based on which device initiated the COT. For example, the WTRU may be restricted to transmit repetitions only in gNB-initiated COT, only in WTRU-initiated COT, or both. Whether repetitions are allowed in gNB-initiated COT, WTRU-initiated COT, or both may be semi-statically configured by RRC or indicated via DCI. The WTRU may be configured to allow Type A only, Type B only, or Type A and B repetitions based on which device initiated the COT.

[0154] The WTRU may select which COT to transmit a repetition on depending on the length of the FFP or the remaining FFP duration. For example, if the length of the repetition transmission exceeds the remaining time of the gNB FFP and the WTRU is configured with a next FFP that has a duration long enough to accommodate the repetition duration, the WTRU may transmit the repetition on the WTRU-initiated COT. If the WTRU-configured FFP start time occurs too far in the future or if the configured WTRU-initiated COT FFP duration is insufficient to transmit a complete repetition, the WTRU may rate-match the repetition to accommodate the remaining gNB FFP duration.

[0155] The WTRU may be configured with dedicated WTRU-initiated COT FFP parameters, e.g., FFP periodicity, starting offset, and FFP duration, if WTRU-initiated COT is used for repetitive transmissions. This configuration may be semi-statically configured via dedicated signaling (e.g., via RRC signaling, via MAC CE, or via DCI). The FFP parameters may be mapped to a repetition type (e.g., type A or B) and / or a repetition parameter (e.g., repetition duration and number of repetitions).

[0156] The WTRU may start a WTRU-initiated COT if a repeat transmission is scheduled to start immediately after a successful Clear Channel Assessment (CCA) (i.e., at the start of a WTRU-initiated FFP). If the WTRU is configured with multiple FFP configurations, the WTRU may select an FFP configuration that has an FFP start aligned with the start of a scheduled repeat transmission. If the start of a scheduled repeat does not align with the start of a WTRU-initiated FFP start time, the WTRU may transmit (e.g., padding bits) to start the channel until the scheduled repeat.

[0157] If an IDLE period interrupts a WTRU repeat transmission, the WTRU may cancel the remaining repeat transmissions. The WTRU may suspend transmission until completion of the IDLE period and resume repeats at the start of a new FFP. The WTRU may distinguish how the IDLE period affects the repeat transmission process depending on whether the IDLE period is initiated by the gNB or the WTRU. For example, if the IDLE period occurs at the end of an FFP initiated by the WTRU, the WTRU may cancel the remaining repeat transmissions. If the WTRU shares a COT initiated by the gNB, the WTRU may suspend transmission until completion of the IDLE period and resume repeat transmissions.

[0158] The WTRU may determine an overlap between a PUSCH repetition of a first priority (e.g., priority index 0) and a PUCCH or PUSCH transmission of a second priority (e.g., priority index 1). It may be beneficial to avoid a transmission gap that would require an LBT before a subsequent repetition.

[0159] In one embodiment, the WTRU may cancel a PUSCH repeat transmission of a first priority (e.g., priority index 0) for a time symbol where there is an overlap with a transmission of another priority (e.g., priority index 1). In the remaining time symbols, the WTRU may transmit the same modulation symbols and reference signals as if cancellation had not occurred in the overlapped symbols.

[0160] In one embodiment, the WTRU may consider time symbols where there is overlap to be "invalid symbols" for purposes of determining a set of actual repetitions from nominal repetitions according to the procedure defined for PUSCH repetition type B. Non-overlapping symbols may be considered "potentially valid" symbols, and the WTRU may define an actual repetition as a contiguous set of potentially valid symbols. The WTRU may transmit an actual repetition of a single symbol in this scenario even if it would not be the case based on rules applicable to PUSCH repetition type B.

[0161] In one embodiment, the WTRU may determine the net repetition for a set of consecutive symbols where there is overlap. The WTRU may multiplex the overlapping transmissions and the net repetitions of priority index 1 into a single transmission. Such an embodiment may be applicable when the transmissions of priority index 1 are PUCCH transmissions and multiplexing of UCI of priority index 1 on PUSCH of priority index 0 is supported.

[0162] The WTRU may be configured or granted resources for transmitting multiple TBs. Each TB may have multiple repetitions. The time resources for each repetition of each TB may be determined based on a mapping rule. The mapping rule may cycle through all repetitions of a TB first before cycling through all repetitions of a subsequent TB. The mapping rule may cycle through every first repetition of every TB before cycling through every second repetition of every TB.

[0163] Figure 9 shows an example of repetition mapping when multi-TTI scheduling is used and transmission cycles are performed first per TB and then per repetition. In Figure 9, there are three TBs, each TB has two repetitions, and each nominal transmission contains five symbols. As shown in Figure 9, a repetition of TB (repetition 1 of TB1, repetition 1 of TB2, repetition 1 of TB3) is transmitted, then a second repetition of TB (repetition 2 of TB1, repetition 2 of TB2, repetition 2 of TB3) is transmitted.

[0164] Figure 10 shows an example of repetition mapping when multi-TTI scheduling is used and transmission cycles are performed first per repetition and then per TB. In Figure 10, there are three TBs, each TB has two repetitions, and each nominal transmission contains five symbols. As shown in Figure 10, all repetitions of the first TB are transmitted (TB1 repetition 1, TB1 repetition 2), then all repetitions of the second TB are transmitted (TB2 repetition 1, TB2 repetition 2), then all repetitions of the third TB are transmitted (TB3 repetition 1, TB3 repetition 2).

[0165] Each of the repeats shown in Figures 9 and 10 may be a nominal repeat, which may be divided or segmented into multiple real repeats. In Figure 9, nominal repeat TB2,rep 1 is divided into two real repeats, nominal repeat TB3,rep 1 is divided into two real repeats, nominal repeat TB2,rep 2 is divided into two real repeats, and nominal repeat TB3,rep 2 is divided into two real repeats. In Figure 10, nominal repeat TB1,rep 2 is divided into two real repeats, nominal repeat TB2,rep 1 is divided into two real repeats, and nominal repeat TB3,rep 2 is divided into two real repeats.

[0166] If the WTRU is scheduled with a single TB using repetition, then both embodiments (cycling every TB then repetition in FIG. 9 and cycling first every repetition then every TB in FIG. 10) will yield the same result. Similarly, if the WTRU is scheduled with a single repetition per TB, then both embodiments (cycling every TB then repetition in FIG. 9 and cycling first every repetition then every TB in FIG. 10) will yield the same result. In this case, the WTRU may transmit a set of TBs using sub-slot multi-TTI scheduling. This may allow for the transmission of n TBs in m slots, where m <nである。

[0167] In one embodiment, the WTRU may transmit a single TB per slot. In such a case, nominal repetitions of a TB may be mapped to non-adjacent slots. For example, each TB may be configured with or associated with a slot offset and periodicity. The slot periodicity may be fixed for some or all TBs. For example, a first TB may be mapped to a slot with offset 0 and periodicity 3, a second TB may be mapped to a slot with offset 1 and periodicity 3, and a third TB may be mapped to a slot with offset 2 and periodicity 3. In such an example, if each TB has three repetitions, the first TB may have its repetitions mapped to slots 1, 4, 7, the second TB may have its repetitions mapped to slots 2, 5, 8, and the third TB may have its repetitions mapped to slots 3, 6, 9. In each slot, a TB may have multiple nominal or real repetitions.

[0168] The WTRU may be configured with a table having elements indicating the number of repetitions, slot offset, slot periodicity, and number of TBs. The scheduling DCI may provide an index that points to a set of parameters found in the table.

[0169] FIG. 11 shows an example of rotation with a single TB per slot. In this example, TB1 has three repetitions of three symbols each, TB2 has three repetitions of four symbols each, and TB3 has five repetitions of two symbols each. In some examples, all TBs scheduled in multi-TTI scheduling may have the same number of repetitions and the same number of symbols per repetition. In FIG. 11, TB1 is transmitted in slots 1 and 4, TB2 is transmitted in slots 2 and 5, and TB3 is transmitted in slots 3 and 6. The nominal repetitions of a TB may be split or segmented and may span multiple non-adjacent slots. For example, the second nominal repetition of TB2 in this example is split, with the first real repetition transmitted in the second slot and the second real repetition transmitted in the fifth slot.

[0170] The WTRU may determine the repetition factor depending on the number of repetitions or the number of different TBs in a slot. For example, the WTRU may transmit a single DM-RS in a slot if all repetitions in the slot are for the same TB.

[0171] The WTRU may be granted or configured to transmit multiple TBs, where each TB may have multiple repetitions. The WTRU may receive an indication of a first HARQ process ID and may determine subsequent HARQ process IDs for subsequent TBs depending on the rotation / mapping type. For example, the HARQ process ID may increment every slot, or every repetition, or every set of repetitions. The increment method and step size may be configurable, fixed, or dynamically indicated.

[0172] For configured grant transmissions, the WTRU may indicate the HARQ process ID in the CG-UCI. The HARQ process ID indication may be provided in all CG-UCIs or in a subset of CG-UCI transmissions. The increment method may be fixed or may be indicated by the WTRU in at least one CG-UCI.

[0173] In one embodiment, a WTRU may be granted or configured with resources to transmit repetitions of a TB over multiple slots. For example, the WTRU may have a nominal repetition that has a duration longer than the duration of a slot. In such a case, the WTRU may segment the repetition and transmit different portions of the TB in different virtual repetitions. For example, the nominal repetition may be segmented into multiple virtual repetitions, and the TB may be segmented such that a portion of the TB is transmitted in each virtual repetition associated with the nominal repetition.

[0174] In one embodiment, the WTRU may map each real repetition to a single slot. The TDRA for each real repetition within a nominal repetition may be fixed such that the same time resource is used in all slots of the nominal repetition.

[0175] The WTRU may receive a HARQ-ACK for at least one TB of the set of TBs scheduled via multi-TTI scheduling. Upon receiving an ACK for a TB, the WTRU may not need to continue transmitting repetitions for that TB. In some embodiments, not transmitting repetitions for a single TB may lead to a transmission gap that may lead to the need to perform an LBT before other repetitions.

[0176] The WTRU may reuse resources originally allocated to the first TB (e.g., for which it received an ACK) for the repetitive transmission of the second TB. The second TB may be a TB for which the WTRU has already transmitted some repetitions. The second TB may be a new TB for which the WTRU has not yet transmitted any repetitions.

[0177] In one embodiment, the WTRU may shift the remaining repetitions and TBs to use resources originally allocated to the ACK'ed TBs.

[0178] In one embodiment, the WTRU may be assigned resources for repetition of a HARQ process (e.g., not for a specific TB). The WTRU may receive an indication to transmit a new TB using the HARQ process for which it received an ACK. The indication may be received by the WTRU in the same message in which it receives the ACK (e.g., CG-DFI). The indication may be received in a new DCI. The indication may be received via RRC signaling. The new TB may be transmitted using the repetition resources associated with the HARQ process. Different HARQ processes may have different repetition numbers. The WTRU may include an indication of the repetition number in a repetition element (e.g., CG-UCI).

[0179] In one embodiment, the WTRU may remap the remaining repetitions to take into account the newly freed UL resources that were originally mapped to the ACKed TB. Such remapping may be indicated to the WTRU or may be autonomously decided by the WTRU. Before remapping the remaining TBs, the WTRU may acknowledge the remapping to the gNB. In one embodiment, the WTRU may be triggered to transmit at least one element (e.g., CG-UCI or UCI) in the remapped repetitions.

[0180] The WTRU may cycle through different TBs in a multi-TTI grant. Each TB may be mapped to a different slot, and each slot may be associated with a different HARQ process. In a slot, the WTRU may include one or more repetitions for the associated HARQ process. The WTRU may or may not complete the required number of repetitions in that slot. If the WTRU does not complete the required number of repetitions, the WTRU may complete the remaining repetition transmissions on a subsequent scheduled multi-TTI grant (or other grant).

[0181] For a given multi-TTI grant, the WTRU may perform transmissions on all TTIs after following a single LBT for any of the TTIs. If the LBT fails in a given TTI, the WTRU may attempt another LBT procedure for the next TTI. For a TB transmission attempt that fails on a given TTI due to LBT, the WTRU may cycle to the next TB / HARQ process. The WTRU may skip or postpone repeat transmissions that fail due to LBT and behave as if they were transmitted.

[0182] The WTRU may map the LBT-failed TB transmission to the next TTI or a different TTI in the grant if the HARQ process for the next TTI does not contain a pending TB (e.g., no other / previous pending TBs were transmitted on the HARQ process associated with the slot) and / or if the LBT-failed TB was not previously transmitted on a different HARQ process. The different TTI may be the first TTI available in the grant after the WTRU finishes cycling through the TBs. For example, the WTRU may add the TB repetition to the end (e.g., to the end of the grant) after cycling through the other HARQ processes. The WTRU may multiplex the HARQ processes associated with the dropped TB / repetition parts of the UCI to be multiplexed on the PUSCH transmission. This may depend on or be based on whether the selected TTI on which the TB / repetition is transmitted is associated with a different HARQ process than the HARQ process used to originally transmit the TB.

[0183] If multiple repetitions of a TB are transmitted before cycling to another TB, the WTRU may skip the repetition where the LBT failed. If all TBs are cycled initially, the WTRU may delay the TB transmission until the next PUSCH opportunity where the LBT is successful. The WTRU may shift the transmission sequence by an offset upon LBT failure to transmit a given repetition on a multi-TTI grant. The offset may be configured (e.g., by higher layers, RRC, or DCI) or may be predetermined as the number of repetitions per TB. In an example transmission (xy), x may be the number of TBs and y may be the number of repetitions. The WTRU may transmit TB repetitions of "1.1 1.2 2.1 2.2 3.1 3.2 4.1 4.2" using the first cycling method, assuming there are four TBs, each repeated twice. In the second rotating method, the WTRU may transmit TB repetitions of "1.1 2.1 3.1 4.1 1.2 2.2 3.2 4.2." If the WTRU uses the second rotating method and the LBT fails for 1.1, the WTRU may skip transmitting 2.1 since the WTRU may not transmit anything for the first TB until the fourth opportunity. The WTRU may shift the entire TB transmission sequence by an offset if the LBT fails to transmit a repetition.

[0184] The WTRU may be configured with a common SLIV / K for all TBs in a multi-slot transmission. Alternatively, the SLIV / K may be set for each TB individually. Whether a common or TB-specific repetition configuration is used may depend, for example, on the number of TBs scheduled by the grant, the traffic characteristics of the TB (e.g., URLLC or eMBB), the signaling method (or associated overhead) used to indicate the repetition parameter (e.g., via an RRC table or DCI), or the channel characteristics (e.g., Reference Signal Received Power (RSRP)).

[0185] The repetition parameters for each TB may depend, for example, on one or more of the following: characteristics of the TB (e.g., TB length or QoS requirements), resources scheduled for TB transmission (e.g., TB start / end location within a slot), relative positions of consecutive TBs (e.g., in a TDD scenario, if two TBs are scheduled close in time, the first TB may be limited in the number of possible repetitions), the slot format of the slot in which the particular TB is transmitted, or channel characteristics (e.g., RSRP, channel occupancy).

[0186] The WTRU may select a SLIV / K common to all TBs or specific to each TB in a multi-slot grant via an explicit indication in the scheduling DCI. The repetition property may be indicated via an existing DCI format with one or more reused spare bits, via an extended DCI field, or via a new DCI. If only one configuration is present or if the field used to indicate a TB-specific repetition parameter is not present, the WTRU may interpret the repetition parameter as common to all TBs scheduled via the DCI.

[0187] The repetition parameters may be semi-statically configured (e.g., via RRC signaling) and stored via a table. The table may be configured separately and the multi-slot scheduling DCI may indicate the repetition parameters to be used for the TBs in the grant via a pointer to a specific SLIV / K. A table (e.g., an RRC table) may be used to indicate resources for multi-TB transmission and may indicate the repetition format / parameters for each TB.

[0188] Although the features and elements are described above in certain combinations, one skilled in the art will understand that each feature or element may be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. 1. A wireless transmit / receive unit (WTRU), comprising: A transceiver; a processor; the transceiver and the processor are configured to receive information for transmitting uplink data, the information indicating a first number of nominal repetitions and a first number of symbols for transmission in each of the first number of nominal repetitions; The processor is further configured to determine a set of symbols associated with a first nominal repetition of the first number of nominal repetitions; The transceiver and the processor are further configured to transmit a second number of actual repetitions in symbols associated with the first nominal repetition based on the set of symbols associated with the first nominal repetition, the second number of actual repetitions and the symbols used to transmit the second number of actual repetitions being based on an occurrence of an event in the set of symbols associated with the first nominal repetition, and the second number of actual repetitions being further determined based on whether the event is a channel occupancy time (COT), the COT being initiated by a WTRU; the set of symbols associated with the first nominal repetition includes one or more subsets of consecutive uplink symbols, each of the one or more subsets of consecutive uplink symbols including at least two symbols, one subset of the one or more subsets of consecutive uplink symbols not overlapping with another subset of the one or more subsets of consecutive uplink symbols; The transceiver and the processor, upon a condition that the event occurs during the set of symbols associated with the first nominal repetition, transmitting a first actual repetition in one or more uplink symbols of the one or more subsets of consecutive uplink symbols prior to the occurrence of the event; and transmitting, on a condition that a channel access procedure is successful, a second actual repeat after the first actual repeat transmission in one or more uplink symbols of the one or more subsets of consecutive uplink symbols after the occurrence of the event. W.T.R.U.

2. The WTRU of claim 1 , wherein the event is at least one of a channel occupation time (COT) end, a channel access resource, a channel access procedure result, a fixed frame period (FFP) idle period start time, or an FFP idle period end time.

3. 2. The WTRU of claim 1, wherein, based on the event, one or more of the symbols of the second number of actual repetitions create a channel occupation time (COT) gap for transmitting uplink control information (UCI) on a physical uplink control channel (PUCCH).

4. 2. The WTRU of claim 1, wherein the channel access procedure is based on at least one of a channel occupation time (COT) timing, an initiator of the COT, a fixed frame period (FFP) timing, a previous channel access procedure result, whether a gap precedes a repetition, a size of the gap between repetitions, or a cause of the gap between repetitions.

5. 2. The WTRU of claim 1, wherein an actual repetition of the second number of actual repetitions includes at least one of a configured grant uplink control information (CG-UCI), a demodulation reference signal (DM-RS), a scheduling request (SR), a channel state information (CSI), a hybrid automatic repeat request (HARQ) acknowledgement (ACK), or a transport block (TB).

6. 10. The WTRU of claim 1, wherein the transceiver and the processor are further configured to receive configuration information regarding resources for performing the channel access procedure, the resources including at least one of a set of time instances, a set of frequency domains, or a beam.

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