Transmission suitability and grant-free access

Abstract

A system for transmission adaptation and grant-free access in unlicensed bands is disclosed. [Solution] A WTRU may receive a set of candidate resources that may be used for transmission and may periodically perform CCA on a channel (e.g., before transmitting on that channel). If the channel is determined to be free, the WTRU may determine a resource for transmission from the candidate resources. The resource may be determined based on the time remaining in a time period. For example, if there is less time remaining in a time period, the WTRU may determine to transmit on a resource that includes more frequency resources. The WTRU may determine a MIMO scheme based on the number of frequency resources. The WTRU may send a transmission on the resource, and the transmission may include a DM-RS. The DM-RS may indicate to a receiver of the transmission the resources used from the transmission.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority from U.S. Provisional Patent Application No. 62 / 500,533, filed on May 3, 2017, the entire disclosure of which is incorporated herein by reference.

Background Art

[0002] Mobile communications are continuously evolving. The fifth generation may be referred to as 5G. Previous (legacy) generations of mobile communications can be, for example, the fourth generation (4G) Long - Term Evolution (LTE). Mobile wireless communications implement various radio access technologies (RATs) such as New Radio (NR). Use cases for NR can include, for example, Extreme Mobile Broadband (eMBB), Ultra - Reliable Low - Latency Communications (URLLC), and Massive Machine - Type Communications (mMTC).

Summary of the Invention

[0003] Systems, methods, and means for transmission adaptation and grant - free access in, for example, unlicensed bands are disclosed. A flexible transmission boundary can be provided for transmission adaptation (e.g., time period and / or time unit). A grant - free access resource pool can be provided. Unlicensed operations can be provided in a beam - based system, for example, using a resource pool and / or Clear Channel Assessment (CCA).

[0004] A wireless transmit / receive unit (WTRU) can receive an indication and / or a set of candidate resources that can be used for transmission. The WTRU can perform a clear channel assessment (CCA) periodically on a channel (e.g., before transmitting on that channel) to determine whether that channel is free for transmission. If the channel is determined to be free, the WTRU can determine a resource for transmission from the candidate resources (e.g., in this case, the resource can refer to one or more time resources and / or frequency resources). The resource can be determined based on the time remaining within a time period. For example, if the time remaining within the time period is shorter, the WTRU can determine to transmit on a resource that includes more frequency resources. The WTRU can determine a multiple-input multiple-output (MIMO) scheme based on the number of frequency resources used for transmission. The WTRU can send a transmission using the determined resource, and the transmission can include a demodulation reference signal (DM-RS). The DM-RS can indicate to the receiver of the transmission the resource used for transmission.

Brief Description of the Drawings

[0005]

Figure 1A

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[0006] With reference to various figures, the description of exemplary embodiments will be detailed. It should be noted that this description provides detailed examples of possible embodiments, but those details are intended to be illustrative and in no way limit the scope of this application.

[0007] FIG. 1A is a diagram showing an exemplary communication system 100 in which one or more of the disclosed embodiments can be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcasting, etc., to a plurality of wireless users. The communication system 100 enables a plurality of wireless users to access such content through sharing of system resources including wireless bandwidth. For example, the communication system 100 can employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), etc.

[0008] As shown in FIG. 1A, the communication system 100 can include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104 / 113, a core network (CN) 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d (any of which can be referred to as a “station” and / or “STA”) can be configured to transmit and / or receive wireless signals and can be a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a wristwatch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., a robot and / or other wireless devices operating in the context of an industrial and / or automated processing chain), a home electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d can also be interchangeably referred to as a UE.

[0009] The communication system 100 may include base station 114a and / or base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as CN106 / 115, Internet 110, and / or other network 112. For example, base stations 114a, 114b may be a base transceiver station (BTS), Node-B, eNode B, home Node B, home eNode B, gNB, NR NodeB, site controller, access point (AP), wireless router, etc. Although base stations 114a, 114b are each depicted as a single element, it will be understood that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0010] Base station 114a can be part of RAN104 / 113, and RAN104 / 113 can also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. Base station 114a and / or base station 114b can be configured to transmit and / or receive radio signals on one or more carrier frequencies, which can be referred to as cells (not shown). These frequencies can be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell can provide coverage for wireless services to a specific geographic area that can be relatively fixed or can change over time. A cell can be further divided into cell sectors. For example, the cell associated with base station 114a can be divided into three sectors. Thus, in one embodiment, base station 114a can include three transceivers, for example, one transceiver for each sector of the cell. In an embodiment, base station 114a can employ MIMO technology and can utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

[0011] Base stations 114a, 114b can communicate with one or more of WTRUs 102a, 102b, 102c, 102d via air interface 116, and air interface 116 can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). Air interface 116 can be established using any suitable radio access technology (RAT).

[0012] More specifically, as described above, the communication system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in RAN104 / 113 and the WTRUs 102a, 102b, 102c can implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish air interfaces 115 / 116 / 117 using Wideband CDMA (WCDMA (registered trademark)). WCDMA can include communication protocols such as High Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High Speed Downlink (DL) Packet Access (HSDPA) and / or High Speed UL Packet Access (HSUPA).

[0013] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that can establish air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-A Pro.

[0014] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as NR radio access that can establish air interface 116 using New Radio (NR).

[0015] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can implement both LTE radio access and NR radio access using, for example, the dual connection (DC) principle. Accordingly, the air interface utilized by the WTRUs 102a, 102b, 102c can be characterized by transmissions to / from multiple types of radio access technologies and / or multiple types of base stations (e.g., eNBs and gNBs).

[0016] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as IEEE 802.11 (e.g., wireless fidelity (WiFi)), IEEE 802.16 (e.g., WiMAX (Worldwide Interoperability for Microwave Access)), 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 (registered trademark)), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0017] The base station 114b in FIG. 1A can be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point, and can utilize any suitable RAT to facilitate wireless connectivity in a local area, such as an office, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d can implement a wireless technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d can implement a wireless 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 can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell or a femto cell. As shown in FIG. 1A, the base station 114b can have a direct connection to the Internet 110. Thus, it is possible that the base station 114b is not required to access the Internet 110 via the CN 106 / 115.

[0018] RAN 104 / 113 can be in communication with CN 106 / 115, where CN 106 / 115 can be any type of network configured to provide voice, data, applications, and / or VoIP services to one or more of WTRUs 102a, 102b, 102c, 102d. The data can have various quality of service (QoS) requirements, such as separate throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 / 115 can provide call control, billing services, mobile location information services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in Figure 1A, it will be understood that RAN 104 / 113 and / or CN 106 / 115 can be in direct or indirect communication with other RANs that employ the same or a different radio access technology (RAT) as RAN 104 / 113. For example, in addition to being connected to RAN 104 / 113 that can utilize NR radio technology, CN 106 / 115 can also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0019] CN106 / 115 can also serve as a gateway for WTRU102a, 102b, 102c, 102d to access the PSTN108, the Internet 110, and / or other networks 112. The PSTN108 can include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 can include a global system of interconnected computer networks and devices that use common communication protocols, such as TCP, UDP, and / or IP in the TCP / IP Internet protocol suite. The network 112 can include a wired communication network and / or a wireless communication network that is owned and / or operated by another service provider. For example, the network 112 can include another CN that is connected to one or more RANs that can employ the same RAT or a different RAT as the RAN104 / 113.

[0020] Some or all of the WTRU102a, 102b, 102c, 102d in the communication system 100 can include a multimode function (e.g., the WTRU102a, 102b, 102c, 102d can include multiple transceivers to communicate with different wireless networks via separate wireless links). For example, the WTRU102c shown in Figure 1A can be configured to communicate with a base station 114a that can employ a cellular-based wireless technology and a base station 114b that can employ IEEE802 wireless technology.

[0021] Figure 1B is a system diagram showing an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 can 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, a non-removable memory 130, a removable memory 132, a power supply 134, a GPS chipset 136, and / or other peripheral devices 138. It will be understood that the WTRU 102 can include any sub-combination of the above elements while maintaining consistency with the embodiments.

[0022] The processor 118 can be a general-purpose processor, a dedicated 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), an FPGA circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, and the transceiver 120 can be coupled to the transmit / receive element 122. Although Figure 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0023] The transceiver element 122 can be configured to transmit signals to a base station (e.g., base station 114a) or receive signals from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transceiver element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transceiver element 122 can be an emitter / detector configured to transmit and / or receive, for example, IR signals, UV signals, or visible light signals. In yet another embodiment, the transceiver element 122 can be configured to transmit and / or receive both RF signals and optical signals. It will be understood that the transceiver element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0024] Although the transceiver element 122 is depicted as a single element in FIG. 1B, the WTRU 102 can include any number of transceiver elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transceiver elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0025] The transceiver 120 can be configured to modulate signals to be transmitted by the transceiver element 122 and demodulate signals received by the transceiver element 122. As described above, the WTRU 102 can have a multi-mode function. Thus, the transceiver 120 can include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs such as, for example, NR and IEEE 802.11.

[0026] The processor 118 of the WTRU 102 can be coupled to 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) and can receive user input data therefrom. The processor 118 can also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Additionally, the processor 118 can access information in and store data in any type of suitable memory, e.g., non-removable memory 130 and / or removable memory 132. The non-removable memory 130 can include RAM, ROM, a hard disk, or any other type of memory storage device. The removable memory 132 can include a SIM card, a memory stick, an SD memory card, etc. In other embodiments, the processor 118 can access information in and store data in a memory that is not physically located on the WTRU 102, e.g., on a server or a home computer (not shown).

[0027] The processor 118 can receive power from a power supply 134 and can be configured to distribute and / or control power to other components in the WTRU 102. The power supply 134 can be any suitable device for powering the WTRU 102. For example, the power supply 134 can include one or more dry cells (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), a solar cell, a fuel cell, etc.

[0028] Processor 118 can also be coupled to a GPS chipset 136, which can be configured to provide location information (e.g., longitude and latitude) regarding the current position of WTRU 102. WTRU 102 can receive location information from a base station (e.g., base stations 114a, 114b) via air interface 116 in addition to, or in place of, information from GPS chipset 136, and / or can determine its position based on the timing of signals received from two or more neighboring base stations. It will be understood that WTRU 102 can obtain location information through any suitable positioning method while maintaining consistency with the embodiments.

[0029] Processor 118 can also be further coupled to other peripheral devices 138, which can include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connections. For example, peripheral devices 138 can include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photos and / or video), a USB port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulation (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, etc. Peripheral devices 138 can include one or more sensors, which can 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, and / or a humidity sensor.

[0030] The WTRU 102 can include full-duplex radio in which some or all of the transmission and reception of signals (associated with a particular subframe, for example, for both UL (e.g., for transmission) and DL (e.g., for reception)) can be parallel and / or simultaneous. The full-duplex radio can include an interference management unit 139 for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In embodiments, the WTRU 102 may include half-duplex radio for some or all of the transmission and reception of signals (associated with a particular subframe, for example, for either uplink (e.g., for transmission) or downlink (e.g., for reception)).

[0031] Figure 1C is a system diagram showing the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 can employ E-UTRA radio technology to communicate with the WTRU 102a, 102b, 102c via the air interface 116. The RAN 104 can also be in communication with the CN 106.

[0032] The RAN 104 can include eNode-Bs 160a, 160b, 160c, although it will be understood that the RAN 104 can include any number of eNode-Bs while maintaining consistency with the embodiments. Each of the eNode-Bs 160a, 160b, 160c can include one or more transceivers for communicating with the WTRU 102a, 102b, 102c via the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c can implement MIMO technology. Thus, the eNode-B 160a can use multiple antennas, for example, to transmit a radio signal to the WTRU 102a and / or to receive a radio signal from the WTRU 102a.

[0033] Each of eNode-Bs 160a, 160b, and 160c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, etc. As shown in FIG. 1C, eNode-Bs 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0034] CN 106 shown in FIG. 1C can include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. Each of the above elements is depicted as part of CN 106, but it will be understood that any of these elements can be owned and / or operated by an entity other than the CN operator.

[0035] MME 162 can be connected to each of eNode-Bs 162a, 162b, and 162c in RAN 104 via the S1 interface and can act as a control node. For example, MME 162 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, activating / deactivating bearers, selecting a specific serving gateway during the first connection of WTRUs 102a, 102b, and 102c, etc. MME 162 can provide control plane functions for performing handovers between RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and / or WCDMA.

[0036] SGW164 can be connected to each of eNode Bs 160a, 160b, and 160c in RAN104 via the S1 interface. SGW164 can generally route and transfer user data packets to / from WTRUs 102a, 102b, and 102c. SGW164 can perform other functions, such as fixing the user plane during handover between eNode Bs, triggering paging when DL data is available for WTRUs 102a, 102b, and 102c, and managing and storing the contexts of WTRUs 102a, 102b, and 102c.

[0037] SGW164 can be connected to PGW166, and PGW166 can provide WTRUs 102a, 102b, and 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRUs 102a, 102b, and 102c and IP-enabled devices.

[0038] CN106 can facilitate communication with other networks. For example, CN106 can provide WTRUs 102a, 102b, and 102c with access to a circuit-switched network such as PSTN 108 to facilitate communication between WTRUs 102a, 102b, and 102c and conventional landline communication devices. For example, CN106 can include, or be capable of communicating with, an IP gateway (such as an IP multimedia subsystem (IMS) server) that serves as an interface between CN106 and PSTN 108. In addition, CN106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers.

[0039] Although the WTRU is described as a wireless terminal in FIGS. 1A - 1D, in certain representative embodiments, it is contemplated that such a terminal may (e.g., temporarily or permanently) use a wired communication interface to a communication network.

[0040] In a representative embodiment, the other network 112 may be a WLAN.

[0041] A WLAN in infrastructure basic service set (BSS) mode can have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP can have an access or interface to a distribution system (DS) that carries traffic in and out of the BSS or another type of wired / wireless network. Traffic from outside the BSS to an STA can arrive through the AP and be delivered to the STA. Traffic originating from an STA to a destination outside the BSS can be sent to the AP and delivered to their respective destinations. Traffic between STAs within the BSS can be sent through the AP, for example, if the source STA can send the traffic to the AP and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or called peer-to-peer traffic. Peer-to-peer traffic can be sent (e.g., directly) between the source STA and the destination STA using direct link setup (DLS). In certain representative embodiments, the DLS can use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using independent BSS (IBSS) mode can be without an AP, and STAs within the IBSS or using the IBSS (e.g., all of the STAs) can communicate directly with each other. The IBSS mode of communication can sometimes be called the "ad hoc" mode of communication in this specification.

[0042] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, the AP can transmit beacons on a fixed channel such as the primary channel. The primary channel can be of a fixed width (e.g., a bandwidth of 20 MHz width) or a width dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In certain representative embodiments, for example in an 802.11 system, the Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) scheme can be implemented. Regarding CSMA / CA, STAs including the AP (e.g., any STA) can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that particular STA can back off. Only one STA (e.g., only one station) can transmit at any given time in a given BSS.

[0043] A High Throughput (HT) STA can use a channel of 40 MHz width for communication, for example, via a combination of the primary 20 MHz channel and a 20 MHz channel that is adjacent or non - adjacent to form a channel of 40 MHz width.

[0044] Very High Throughput (VHT) STAs are capable of supporting channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. A 40 MHz channel and / or an 80 MHz channel can be formed by combining adjacent 20 MHz channels. A 160 MHz channel can be formed by combining eight adjacent 20 MHz channels or by combining two non - adjacent 80 MHz channels (which can be referred to as an 80 + 80 configuration). For the 80 + 80 configuration, data can be passed through a segment parser after channel encoding, and the segment parser can split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time - domain processing can be performed separately on each stream. Those streams can be mapped onto two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above - described operations for the 80 + 80 configuration can be reversed, and the combined data can be sent to the Media Access Control (MAC).

[0045] The sub-1GHz mode of operation is supported by 802.11af and 802.11ah. The channel operating bandwidth and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports bandwidths of 5 MHz, 10 MHz, and 20 MHz in the TV white space (TVWS) spectrum, and 802.11ah supports bandwidths of 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz that use non-TVWS spectrum. According to an exemplary embodiment, 802.11ah is capable of supporting meter type control / machine type communication, such as MTC devices in a macro coverage area. The MTC devices can have limited capabilities that include specific capabilities, e.g., support for specific and / or limited bandwidths (e.g., only support for those). The MTC devices can include a battery having a battery life that exceeds a threshold (e.g., to maintain a very long battery life).

[0046] A WLAN system that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, includes channels that can be designated as primary channels. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STA that supports the minimum bandwidth operating mode among all the STAs operating in the BSS. In the example of 802.11ah, for an STA (e.g., an MTC type device) that supports (e.g., only supports) the 1MHz mode, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes, the primary channel can be 1MHz wide. Carrier sensing and / or network allocation vector (NAV) setting may depend on the status of the primary channel. For example, if the primary channel is busy due to an STA (supporting only the 1MHz operating mode) transmitting to the AP, the entire available frequency band may be considered busy even if most of those frequency bands remain idle and may be available.

[0047] In the United States, the available frequency band that can be used by 802.11ah is from 902 MHz to 928 MHz. In Korea, the available frequency band is from 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is from 916.5 MHz to 927.5 MHz. The total available bandwidth for 802.11ah is from 6 MHz to 26 MHz depending on the country code.

[0048] Figure 1D is a system diagram showing RAN 113 and CN 115 according to an embodiment. As described above, RAN 113 can employ NR radio technology to communicate with WTRU 102a, 102b, 102c via air interface 116. RAN 113 can also be in communication with CN 115.

[0049] RAN 113 can include gNBs 180a, 180b, 180c, although it will be understood that RAN 113 can include any number of gNBs while maintaining consistency with the embodiment. Each of gNBs 180a, 180b, 180c can include one or more transceivers to communicate with WTRU 102a, 102b, 102c via air interface 116. In one embodiment, gNBs 180a, 180b, 180c can implement MIMO technology. For example, gNBs 180a, 180b can utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, 180c. Thus, gNB 180a can use multiple antennas, for example, to transmit a radio signal to WTRU 102a and / or to receive a radio signal from WTRU 102a. In an embodiment, gNBs 180a, 180b, 180c can implement carrier aggregation technology. For example, gNB 180a can transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers can be on unlicensed spectrum while the remaining component carriers can be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c can implement coordinated multipoint (CoMP) technology. For example, WTRU 102a can receive coordinated transmission from gNB 180a and gNB 180b (and / or gNB 180c).

[0050] WTRU102a, 102b, and 102c are capable of communicating with gNBs 180a, 180b, and 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or the OFDM sub-carrier spacing can be different for each separate transmission, each separate cell, and / or each separate portion of the radio transmission spectrum. WTRU102a, 102b, and 102c are capable of communicating with gNBs 180a, 180b, and 180c using sub-frames or transmission time intervals (TTIs) of various or scalable lengths (e.g., including various numbers of OFDM symbols and / or absolute times of various durations).

[0051] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in a stand-alone configuration and / or a non-stand-alone configuration. In a stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNode-Bs 160a, 160b, and 160c). In a stand-alone configuration, WTRUs 102a, 102b, and 102c can utilize one or more of gNBs 180a, 180b, and 180c as a mobility anchor point. In a stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in an unlicensed band. In a non-stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with / connect to gNBs 180a, 180b, and 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, and 160c. For example, WTRUs 102a, 102b, and 102c can implement the DC principle to communicate with one or more gNBs 180a, 180b, and 180c and one or more eNode-Bs 160a, 160b, and 160c substantially simultaneously. In a non-stand-alone configuration, eNode-Bs 160a, 160b, and 160c can serve as a mobility anchor for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, and 102c.

[0052] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle decisions for radio resource management, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, 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 Figure 1D, gNBs 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0053] CN 115 shown in Figure 1D can include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and optionally data networks (DNs) 185a, 185b. Each of the above-mentioned elements is shown as part of CN 115, but it will be understood that any of these elements can be owned and / or operated by an entity other than the CN operator.

[0054] AMF 182a and 182b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can serve as control nodes. For example, AMF 182a and 182b can authenticate users of WTRUs 102a, 102b, and 102c, support network slicing (e.g., handle separate PDU sessions with different requirements), select specific SMFs 183a and 183b, manage the registration area, terminate NAS signaling, perform mobility management, etc. Network slicing can be used by AMF 182a and 182b to customize CN support for WTRUs 102a, 102b, and 102c based on the type of service utilized by WTRUs 102a, 102b, and 102c. For example, separate network slices can be established for different use cases such as services that rely on ultra-reliable low-latency (URLLC) access, services that rely on enhanced mobile broadband (eMBB) access, services related to machine type communication (MTC) access, etc. AMF 162 can provide control plane functions for performing handovers between RAN 113 and other RANs (not shown) that employ other radio technologies such as LTE, LTE-A, LTE-A Pro, etc., and / or non-3GPP access technologies such as WiFi.

[0055] SMF183a and 183b can be connected to AMF182a and 182b in CN115 via the N11 interface. SMF183a and 183b can also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b can select and control UPF184a and 184b, and configure the routing of traffic passing through UPF184a and 184b. SMF183a and 183b can perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, enforcing policies and controlling QoS, and providing downlink data notifications. The PDU session type can be IP-based, non-IP-based, Ethernet-based, etc.

[0056] UPF184a and 184b can be connected to one or more of gNB180a, 180b, and 180c in RAN113 via the N3 interface, and the N3 interface can provide access to a packet-switched network such as the Internet 110 to WTRU102a, 102b, and 102c to facilitate communication between WTRU102a, 102b, and 102c and IP-compatible devices. UPF184 and 184b can perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-home PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0057] CN115 can facilitate communication with other networks. For example, CN115 can include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN115 and the PSTN108, or can communicate with such an IP gateway. Additionally, CN115 can provide access to other networks 112 to the WTRU102a, 102b, 102c, and the other networks 112 can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRU102a, 102b, 102c can be connected to the DN185a, 185b through the UPF184a, 184b via an N3 interface to the UPF184a, 184b and an N6 interface between the UPF184a, 184b and the local data network (DN) 185a, 185b.

[0058] Considering FIGS. 1A - 1D and the corresponding descriptions of FIGS. 1A - 1D, one or more or all of the functions described herein in relation to one or more of the WTRU102a - d, base stations 114a - b, eNode - B160a - c, MME162, SGW164, PGW166, gNB180a - c, AMF182a - b, UPF184a - b, SMF183a - b, DN185a - b, and / or any other devices described herein can be performed by one or more emulation devices (not shown). An emulation device can be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device can be used to test other devices and / or to simulate network and / or WTRU functions.

[0059] An emulation device can be designed to perform one or more tests on other devices in a laboratory environment and / or in an operator network environment. For example, one or more emulation devices can execute one or more or all functions while being implemented and / or deployed, in whole or in part, as part of a communication network to test other devices within a wired and / or wireless communication network. One or more emulation devices can execute one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. An emulation device can be directly coupled to another device for testing purposes and / or can perform testing using over-the-air wireless communication.

[0060] One or more emulation devices can execute one or more functions including all functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device can be utilized in a testing laboratory and / or in a testing scenario in a wired and / or wireless communication network that is not deployed (e.g., for testing) to perform testing of one or more components. One or more emulation devices can be test equipment. Direct RF coupling and / or wireless communication via an RF circuit (which can include one or more antennas, for example) can be used by an emulation device to transmit and / or receive data.

[0061] Wireless communication is capable of supporting applications with various requirements. For example, some applications may have low latency, while others may have delay tolerance. Some applications may have high reliability, while others may be less critical. Applications can include, for example, enhanced mobile broadband (eMBB), machine type communication (MTC), massive MTC (mMTC), and ultra-reliable low-latency communication (URLLC). Applications may be useful in a wide range of industries such as the automotive industry, health industry, agricultural industry, utility industry, and logistics industry.

[0062] Wireless communication can be deployed using licensed spectrum and / or unlicensed spectrum. Unlicensed spectrum can be used, for example, for non-cellular services and applications such as Wi-Fi, and / or for cellular services (e.g., broadband data services). Unlicensed spectrum can be shared by multiple users who may interfere with each other, which may impose constraints on the use of unlicensed spectrum.

[0063] The operation or use of a cell, transmit-receive point (TRP), or carrier in an unlicensed band can be, for example, stand-alone or assisted by the operation or use of a cell, TRP, or carrier in a licensed band. The assisted deployment scenario can be called licensed-assisted access (LAA). The licensed cell, TRP, or carrier can be a primary or anchor cell, TRP, or carrier.

[0064] For example, to minimize interference and provide fairness among spectrum users, it is possible to consider the coexistence of cellular system operations with unlicensed technologies (e.g., Wi-Fi) and cellular operators in unlicensed spectrum. Mechanisms such as Listen Before Talk (LBT) or Clear Channel Assessment (CCA) can be used (e.g., for fair coexistence). In an example, system nodes such as access points (APs), eNodeBs (eNBs), gNodeBs (gNBs), TRPs, user equipment (WTRUs), etc., can listen to a channel (e.g., a frequency band having a specific center frequency and bandwidth) to determine, for example, whether another user may be using that channel before transmitting on that channel or a portion thereof. Listening for and / or determining usage by another user can include or be based on, for example, measurements (e.g., energy detection).

[0065] LBT, CCA, and LBT / CCA can be used interchangeably herein. A channel can be determined to be busy, occupied, or in use if, for example, a measurement value (e.g., of energy) may be above a threshold. A channel can be determined to be idle, free, clear, or unused if, for example, a measurement value (e.g., of energy) may be below a threshold.

[0066] "Clear", "free", "idle", "unoccupied", and "not busy" can be used interchangeably. "Not clear", "not free", "not idle", "occupied", and "busy" can be used interchangeably. Channel and operating channel can be used interchangeably. CCA failure can mean, for example, that the channel may be busy (e.g., is busy). CCA success can mean, for example, that the channel may be clear.

[0067] Potential transmitters on a channel (e.g., a WTRU having a potential UL transmission and / or an eNB having a potential DL transmission) can evaluate and / or monitor (e.g., receive) the channel before transmission (e.g., to measure and / or determine the presence or interference of signals on the channel) to determine, for example, whether the channel is in use (e.g., is busy and / or is occupied) by another system, user, or signal, etc.

[0068] A potential transmitter can compare the received signal and / or interference from the channel to a criterion (e.g., one or more threshold levels) (e.g., as part of LBT / CCA) to determine, for example, whether the channel may be free (e.g., based on the comparison). A potential transmitter can transmit on that channel, for example, if the potential transmitter determines that the channel may be free. A potential transmitter can refrain from transmitting on the channel, delay a potential transmission, and / or abort a potential transmission, for example, if the potential transmitter determines that the channel may not be free.

[0069] A frame-based device (FBE) can refer to a device whose transmission / reception timing can be fixed and / or structured. A load-based device (LBE) can, for example, not perform LBT / CCA according to a specific frame structure, i.e., at a fixed or defined time. The LBE can perform LBT / CCA, for example, when the LBE has data to transmit.

[0070] A device can refer to a node or device (e.g., a WTRU, eNB, gNB, TRP, STA, or AP) that can transmit and / or receive on licensed and / or unlicensed channels.

[0071] The eNB can be used to refer to or represent one or more of a gNB, TRP, STA, cell, and / or AP, in which case the eNB, gNB, TRP, STA, cell, and AP can be used interchangeably.

[0072] In an example, a device can perform an LBT / CCA check (e.g., to sense energy on a channel) before transmitting on an operating channel or before a burst of transmissions.

[0073] The LBT / CCA time period for channel assessment can be a fixed time and / or can have a minimum time.

[0074] Channel occupancy time (COT) can be the total time that a device can have a transmission on a given channel, for example, without re-evaluating the availability of that channel.

[0075] Maximum COT (MCOT) can be the total time that a device can utilize an operating channel for a given transmission or burst of transmissions.

[0076] The value of MCOT can be configured or permitted (e.g., by regulation). MCOT can be, for example, 4 ms or 10 ms.

[0077] The MCOT for a device can be less than the maximum allowable value, which can be set, for example, by the device manufacturer.

[0078] The idle period can be the time during which the device is able not to transmit on the channel (e.g., a consecutive period of time).

[0079] The idle period can have a minimum value (e.g., 5% of COT for COT) that can be used by the device, for example, during the current fixed frame period.

[0080] For example, if the device knows that one or more operating channels are clear (e.g., during or as a result of LBT / CCA), the device can transmit on one or more clear channels (e.g., immediately).

[0081] For example, if the device knows that an operating channel is occupied (e.g., during or as a result of LBT / CCA), the device can refrain from transmitting on the channel. The device can perform a subsequent LBT / CCA, and the subsequent LBT / CCA can find that the channel is clear.

[0082] For example, if the device knows that an operating channel is occupied (e.g., during or as a result of LBT / CCA), the device can refrain from transmitting on the channel (e.g., during the next fixed frame period).

[0083] The LBT / CCA executed after the LBT / CCA determines that the channel is not clear can include, for example, a waiting time or a backoff time, for example, before checking whether the channel is clear.

[0084] The LBT / CCA that can be executed after the LBT / CCA which may have determined that the channel is not clear can include, for example, a longer period for determining whether the channel may be clear and for subsequent transmission.

[0085] The WTRU can perform CCA to determine, for example, whether the channel may be free. The WTRU can add additional backoff time or waiting time, such as an amount of time for an additional contention window, if the WTRU determines that the channel is not free, for example. The WTRU can re-check before actual transmission if, for example, actual transmission cannot start immediately after it is determined that the channel is free (when it is determined that the channel is free, for example).

[0086] In an example, the WTRU can perform CCA (for example, for at least the amount of time of the check window) if, for example, the WTRU may not be within the check window (for example, 25 μs) before actual transmission. The WTRU can transmit (for example, only transmit) if, for example, it is determined that the channel is free (for example, for at least part of the amount of time of the check window).

[0087] CCA can be, for example, a full CCA or a short CCA. A full CCA can include, for example, adding one or more backoff times when it is possible to determine that the channel is busy. A short CCA can be, for example, a quick check (e.g., an energy detection check) in a check window before the start of a transmission or an intended or planned transmission.

[0088] The WTRU can perform a full CCA (e.g., to determine whether the channel might be free) when, for example, the WTRU can perform CCA for a first subframe (SF) or symbol. The WTRU can perform a short CCA, for example, before transmission (e.g., to re-check that the channel is still free) when there might be a gap between the end of the full CCA and the start of the transmission.

[0089] Access to a cell, on a channel, to a cell, or to a TRP or another node, resource use, or transmission on a resource can be, for example, grant-based, allocation-based, or scheduler-based.

[0090] In an example, the WTRU can perform a transmission (e.g., only perform a transmission) on a set of resources in response to or according to a received grant or allocation of resources. The resources can be, for example, time resources and / or frequency resources.

[0091] The grant or allocation can be provided (e.g., explicitly) in, for example, downlink control information (DCI). The grant or allocation can be configured (e.g., by higher layer signaling) and can be used by the WTRU when, for example, the WTRU can have data to transmit.

[0092] Access to a cell, to the TRP or other nodes, use of resources, or transmission on a channel in a cell can be grantless or grant-free. Grantless and grant-free can be used interchangeably. The resources can be, for example, time resources and / or frequency resources.

[0093] The WTRU can transmit on a set of resources, for example, if the WTRU has transmissions to make. The WTRU can determine or select the resources on which it can transmit, for example, from one or more configured sets of resources. The set of resources can be configured by the eNB.

[0094] Resources can be shared and / or used by multiple WTRUs. The resources can be referred to as contention-based resources. For example, if multiple WTRUs can simultaneously select and / or transmit on the same resource, the transmissions of multiple WTRUs can collide.

[0095] A mechanism for reducing the likelihood of collisions can be included. In an example, resource selection can be determined (e.g., wholly or in part) randomly. Resource selection can be a function of the WTRU-ID. Separate groups of WTRUs can be configured with separate sets of resources.

[0096] The mechanism enables the receiver of a grant-free transmission to identify the transmitter. In an example, the transmission can include an identifier or a partial identifier.

[0097] The WTRU can perform CCA (e.g., in an LTE LAA UL scenario) for transmissions that start, for example, at the boundary of the start of a time period or at the boundary of a time unit that can be within a time period.

[0098] Examples of time periods can include, for example, subframes (SFs), frames, slots, minislots, sets of slots or minislots, TTIs, short TTIs, multi-symbol TTIs, symbols, sets of TTIs, sets of symbols, synchronization bursts, synchronization blocks, sets of synchronization bursts or synchronization blocks, etc. A time period can include one or more time units. Examples of time units can include, for example, symbols, slots, minislots, TTIs, short TTIs, multi-symbol TTIs, sets of symbols, synchronization bursts, synchronization blocks, etc. For example, the WTRU can perform CCA (e.g., perform CCA periodically) on a channel for one or more of the time units included within a time period on that channel until it is determined that the channel is free.

[0099] In an example, the WTRU can perform CCA for transmissions that start, for example, on a subframe (SF) boundary or on the indicated symbol boundaries within an SF. The WTRU can receive a grant, for example, for an SF (e.g., a complete SF or a partial SF) or a set of consecutive subframes. The WTRU can perform CCA, for example, before transmitting on an authorized SF. The WTRU can perform CCA for the next (or subsequent) authorized SF if, for example, the WTRU determines that CCA fails (e.g., the channel may be busy or not idle) (e.g., for a set of SFs that can be authorized). The WTRU can transmit on the SFs within the authorized set of SFs and the remaining SFs if, for example, the WTRU determines that the channel is free for the SFs within the authorized set. For example, if transmission can be continuous, transmission can be performed for subsequent SFs without performing CCA. The WTRU can perform CCA for transmission on the SFs within the set after an interruption if, for example, an interruption can occur in the transmission.

[0100] A WTRU that performs CCA for transmissions on a specific time period boundary, such as an SF or a specific symbol boundary, may be at a disadvantage in accessing the channel compared to another device (e.g., a WiFi device) that is not restricted to a specific boundary for CCA or transmission.

[0101] A WTRU that can transmit based on receiving a resource grant, schedule, or allocation may be at a disadvantage in accessing the channel compared to another device (e.g., a WiFi device) that is not restricted to waiting for a grant, schedule, or allocation.

[0102] For example, systems, methods, and means for transmission adaptation and / or grant-free access in an unlicensed band are disclosed. A flexible transmission boundary can be provided for transmission adaptation. A grant-free access resource pool can be provided. Unlicensed operations can be provided in a beam-based system, for example, using a resource pool and / or CCA.

[0103] A flexible transmission boundary can be provided, for example, for transmission adaptation. CCA and transmission can be unrestricted to a time period (e.g., subframe) or time unit. For example, if CCA may be failed for a time unit (e.g., symbol) within a time period (e.g., subframe), CCA can be repeated (e.g., in the next or other time units).

[0104] Frequency resource adaptation can be provided.

[0105] Frequency resources can be adapted, for example, based on the time remaining within a time period for transmission. A set of frequency resources can be selected from a configured set of candidates. For example, if the time remaining within a time period (e.g., one or more time units) is short, the WTRU can select resources for transmission that include more frequency resources.

[0106] A MIMO scheme can be adapted, for example, based on a set of frequency resources used. The MIMO described herein can refer to MIMO or massive MIMO.

[0107] The DM-RS can be used to indicate the frequency resource set being used. The use of slots and mini-slots can be based on available time for transmitting and adapting the position of the DM-RS, for example, based on slots, mini-slots, and / or start time. The DM-RS can be placed at the end time of transmission (e.g., in one or two of the last symbols). A sequence can identify the resource set being used. For example, a sequence that can be used to identify the resource set can be signaled to the WTRU (e.g., signaled by the eNB).

[0108] The new numerology (subcarrier spacing) can be adapted, for example, based on the time remaining within the time period for transmission.

[0109] In cases where the maximum power is exceeded, for example, where the frequency can be limited or adjusted, there can be a shift to the next or some other subsequent time period where the entire amount of time may be available for transmission. For example, to avoid exceeding the maximum power, the TBS can be adjusted and / or the modulation order can be selected (e.g., from a set of candidates). The DM-RS can indicate which TBS and / or modulation order is being used.

[0110] The beam sweeping operation (e.g., the number of beams for sweeping) can be adapted, for example, based on the subcarrier spacing / symbol duration and / or time remaining within the time period for transmission.

[0111] It is possible to provide adaptation of the data size. The amount of data to be transmitted can be adapted, for example, based on the available time for transmission. In an example, for instance, the TBS can be adapted based on the available time for transmission, code block segmentation can be used, and / or the number of code blocks to be transmitted can be changed. For example, multiple mini-slots can be used to enable the transmission of segmented transport blocks.

[0112] For example, adaptation of the control channel can be provided for a delayed control channel and / or a short PUCCH. In an example (for a delayed control channel), the content can be modified, for example, to include A / N for more DL transmissions. In an example (for a short PUCCH), the coverage can be improved by repetition in time or frequency, and / or the CQI can be dropped (if it would not fit, for example). The PUCCH type (e.g., DM-RS based or sequence based) can be determined, for example, based on the available time for transmission.

[0113] It is possible to provide adaptation of the transmission time.

[0114] In an example of the start configuration, the WTRU can be configured with a set of start times or start points. The WTRU can perform CCA with respect to a first start point. The WTRU can try the next or subsequent start points, for example, if the first start point fails the CCA.

[0115] In an example of a short transmission time, the available time for transmission can be a function of when the transmission starts, for example, when the end is fixed or configured.

[0116] In the example of a fixed or configured transmission time, the transmission time can be based on when the WTRU starts transmitting. The WTRU can transmit B complete TBs, where B can be, for example, the number of complete TBs that can fit within the allotted or permitted time period with respect to when the WTRU starts transmitting. In (e.g., an alternative) example, the first or last TB can be short, for example, based on when the WTRU starts, while the other TBs can be of full size.

[0117] It can be possible to provide an indication of the start time and end time. In an example, the WTRU can transmit a reference signal (RS) or a control channel, for example, to indicate the start and / or end of transmission. The RS or control channel can use the same frequency resources, for example, regardless of the subset of frequency resources that can be used. In an example (e.g., an alternative example), the RS location can depend on the subset of frequency resources that can be used.

[0118] It can be possible to provide CCA frequency compliance. In an example, CCA can be performed with respect to a band (e.g., a maximum band) or a set of frequencies that can include all candidate sets of frequencies that can be used by the WTRU. CCA can be performed on multiple sub-bands, for example, to enable the selection of a set of compliant sub-bands. The WTRU can puncture out one or more sub-bands (e.g., not use / measure them), for example, when performing CCA (e.g., to enable the use of sub-bands by other WTRUs).

[0119] The CCA capability of the WTRU can be provided. The WTRU can have or report a capability regarding the time granularity at which the WTRU can perform consecutive CCAs, which can be a function of the subcarrier spacing used, for example.

[0120] A grant-free access resource pool can be provided.

[0121] The resource pool can be configured, for example, with a schedule or pattern in time and / or frequency, and with repetition (e.g., periodicity). The pool can include a candidate set of frequencies. The time resources can be relative to a reference point (e.g., a synchronization burst or block) that can be beam-specific.

[0122] Allocation of the pool and identification of the WTRU can be provided. The WTRU and the resource pool can be allocated to a group. The WTRU can receive, for example, a grant-free mask or RNTI to scramble the CRC of its transmission.

[0123] A resource pool layer can be provided. The WTRU can be configured with a resource pool layer with different resource availabilities (e.g., different repetitions). For example, if the WTRU cannot perform a transmission using the resources of the first layer (e.g., due to the channel being busy N times), the WTRU can perform the transmission using the resources of the second layer (with more frequent resources). The resource pool can have different types of, or different priorities for, transmissions (e.g., URLLC vs. eMBB, transmission vs. retransmission), and / or can be used for those transmissions.

[0124] It is possible to switch to grant-based transmission. The request for the switch can be made, for example, by SR or PRACH on a licensed channel or an unlicensed channel. The request can be made, for example, after a threshold number of times (e.g., for one or more layers) it has been impossible to obtain a channel.

[0125] Unlicensed operations can be provided in a beam-based system, for example, using a resource pool and / or by performing CCA.

[0126] A resource pool can be provided in a beam-based system. In an example, the resource pool can be associated with a beam or BPL. The resource pool can be configured, for example, based on a DL signal (e.g., a beam discovery signal or RS) for measuring quality. The resource pool can be within the same time resource as the synchronization burst or synchronization block of the associated beam. For example, if there is a possibility that a threshold number of times (e.g., N times) of grant-free access may fail (e.g., CCA may fail or an ACK may not be received), another pool associated with another beam can be tried.

[0127] CCA can be performed in a beam-based system. In an example, a received beam for CCA regarding a resource pool associated with a beam can be, for example, a received beam that can be used for beam determination, a beam with the highest RSRP, or a received beam that can be associated with a transmitted beam. The WTRU can perform CCA for one or more (e.g., all) received beams. The WTRU can use the detected highest energy or the detected average energy. The WTRU can perform CCA again (e.g., before transmitting) for a received beam that can correspond to a transmitted beam.

[0128] A flexible transmission boundary can be provided and / or used.

[0129] The WTRU can perform CCA for transmission at the start of a time unit that can be within a time period (e.g., CCA can be performed periodically). In an example, the WTRU can try again at a subsequent time, e.g., a subsequent time unit that can be within the time period (e.g., if CCA fails). The WTRU can continue to perform CCA on time units included within the time period until it is determined that the channel is free (e.g., when CCA passes). The WTRU can start transmitting at a subsequent time unit (e.g., if CCA passes).

[0130] WTRU transmission can end, for example, before or at the end of a time period. WTRU transmission can continue to the next time period.

[0131] In an example, the time period can be an SF and the time unit can be a symbol. The WTRU can determine whether the channel is likely to be free for transmission, for example, at the start of the first symbol within the first SF. The WTRU can determine whether the channel is likely to be free for transmission at the start of the second symbol (e.g., the next symbol) within the first SF (e.g., if the channel is not free). The WTRU can start transmission, for example, starting with the second symbol within the first SF (e.g., if the channel is free). The WTRU can start transmitting a transport block (TB) in the second symbol of the first SF. The last symbol for the transmission of the TB can be a symbol within the first SF, such as the last symbol or the second last symbol within the first SF. The last symbol for the transmission of the TB can be a symbol within the second SF, such as the subsequent SF, the next SF, the next adjacent SF, etc., among a number of examples.

[0132] In an example, the time unit can be an sTTI. The sTTI can be composed of a set of symbols.

[0133] The WTRU can determine the duration for transmission, for example, based on the start point or time of transmission and / or the end point or time. The start point or time can be determined by the WTRU, for example, based on the result of the CCA. The start point or time can be selected by the WTRU from a set of start points or times that can be configured and / or permitted. The end point or time can be fixed, configured, or known. The end point or time can be selected by the WTRU from a set of end points or times that can be configured and / or permitted. The WTRU can determine the duration of transmission from a set of durations that can be configured and / or permitted.

[0134] The WTRU can determine, for example, (i) the amount of data to be transmitted, such as the transport block size (TBS), (ii) one or more frequency resources to be used for transmission, and / or (iii) a set or pattern of frequency resources, such as RE, RB, or PB, to be used for transmission, based on, for example, the start point or time of transmission, the end point or time of transmission, or the duration (e.g., the determined duration).

[0135] Frequency resource adaptation can be provided. The WTRU and / or the eNB or gNB can determine the frequency resources for transmission, for example, based on the start point or time of transmission and / or the end point or time of transmission.

[0136] In an example, the WTRU can transmit on a larger set of frequency resources if, for example, there is a possibility that less time is available for transmission. The WTRU can determine, for example, a start time, an end time, and / or a duration with respect to the transmission. The WTRU can determine the number of resources and / or sets of resources, for example, based on the start time, end time, and / or duration of the transmission.

[0137] The WTRU can use a fixed number of time resources and / or frequency resources to transmit a transport block. The WTRU can select a numerology, for example, based on the amount of time remaining in the transmission occasion from the moment the WTRU may have acquired a channel. In an example, the WTRU can select a first subcarrier spacing and / or a first symbol duration if, for example, the WTRU can acquire the channel at a first time instance where there may be T1 time remaining to transmit the TB. The WTRU may fail to acquire the channel at the first time instance, for example, and (instead) may select a second subcarrier spacing and / or a second symbol duration when acquiring it at a second time instance where, for example, there may be T2 time remaining to transmit the TB. The WTRU can select a larger subcarrier spacing and / or a smaller symbol duration (e.g., for the remaining T2 time) for its transmission if, for example, T2 may be less than T1. The WTRU can be configured with a set of applicable and / or valid subcarrier spacing values and / or symbol duration values that can be used for an unlicensed channel or within that channel. The configuration can be provided, for example, via a broadcast transmission (e.g., in system information transmission) or via a configuration that can be used for grant-free transmission. The configuration can be, for example, group-specific or WTRU-specific and can be provided and / or received via group-specific or WTRU-specific signaling.

[0138] The number of symbols used can be the same regardless of, for example, start time and / or duration. The subcarrier spacing can be determined based on start time and / or duration. In an example, for different start times and / or durations, one (e.g., the same) physical channel structure (e.g., reference signal structure and data RE location) can be used.

[0139] The CP length can be the same for all (e.g., all) subcarrier spacing candidates. The (e.g., maximum) CP length can be determined based on, for example, subcarrier spacing (e.g., alternatively). A WTRU, eNB, or gNB can drop the transmission if, for example, the CP length due to channel conditions may be longer than the maximum CP length.

[0140] Resources can be time resources and / or frequency resources. Resources can be resource blocks (RBs) or physical resource blocks (PRBs). Resources can be continuous in frequency (e.g., consecutive subcarriers). Resources can be dispersed in frequency over, for example, a frequency band or sub-band.

[0141] A set of RBs, PRBs, and / or frequencies (e.g., candidate set) can be configured (e.g., from which a WTRU can determine a subset for transmission). In an example, a WTRU can receive one or more sets of resources (e.g., candidate sets) (e.g., resource patterns) from which the WTRU can select a set or subset (e.g., candidate) for transmission. A WTRU can determine a candidate from a set of candidates for use in transmission based on, for example, the time available for transmission.

[0142] A WTRU can map the modulated symbols of a transport block (TB) to time / frequency resources (e.g., resource elements (REs)) corresponding to a determined candidate from a set of candidates. The WTRU can apply a repetition of a number of modulated symbols (e.g., a small number of symbols), for example, if there is a possibility that the number of REs in the selected candidate is larger than the number of modulated symbols of the TB.

[0143] In an example, a license-exempt transmission in a band (e.g., 5 GHz) can include an interleaved transmission over all transmission sub-bands (e.g., 5 MHz or 20 MHz sub-bands) within that band. The set of resource candidates can be an interleaving pattern from which the WTRU can make a selection. An expansion in frequency resources (e.g., a set with more frequency resources) can correspond to a more dense interleaving pattern.

[0144] The use of a more dense interleaving can result in the WTRU having more (e.g., even more) REs available for transmission than may be necessary for the current TB. The WTRU can transmit additional TBs (e.g., with smaller TBSs) in the remaining available REs.

[0145] A MIMO transmission scheme that can be used for transmission can be determined, for example, based on (e.g., determined) frequency resource candidates and / or start time and duration. For example, when a first frequency resource candidate can be determined, a first MIMO transmission scheme (e.g., space-frequency block coding (SFBC)) can be used. For example, when a second frequency resource candidate can be determined, a second MIMO transmission scheme (e.g., precoder cycling) can be used. The first frequency resource candidate can have a smaller number of frequency resources than the second frequency resource candidate.

[0146] The MIMO transmission scheme can be determined, for example, based on the number of RBs or PRBs in the frequency resource candidate. The first MIMO transmission scheme can be used, for example, when the number of RBs or PRBs in the frequency resource candidate may be greater than a threshold, while the second MIMO transmission scheme can be used, for example, otherwise.

[0147] The transmission rank (e.g., the number of layers) can be determined, for example, based on (e.g., determined) frequency resource candidates and / or start time and duration. For example, when a first frequency resource candidate can be determined, a first transmission rank can be used, while, for example, when a second frequency resource candidate can be determined, a second transmission rank can be used.

[0148] The receiver is capable of determining the frequency resources used in transmission. The WTRU is capable of transmitting a reference signal (RS) such as a demodulation reference signal (DM-RS) in its transmission. The WTRU is capable of transmitting the RS in the PRBs of the transmission (e.g., in a subset of the REs of the transmission), which enables the eNB to determine the set of resources (e.g., candidate set) used for the transmission. The eNB can use the RS transmission, for example, to determine the candidates or set of frequencies used by the WTRU for transmission.

[0149] A mini-slot may be a time unit that can contain fewer symbols than a slot. In an example, a slot can contain 7 symbols, while a mini-slot can contain 2, 3, or 4 symbols.

[0150] The WTRU can transmit the RS at a position within a time unit (e.g., subframe, slot or mini-slot), where, for example, the position can be fixed, known, or configurable. The WTRU can transmit the RS at a position within a time unit that can be determined by the WTRU. The RS can have a position that can be, for example, a nominal, default, or regular position, or can be transmitted at that position. The WTRU can transmit the RS at a position that can be, for example, not a nominal, default, or regular position. The RS transmission can be considered flexible RS transmission, for example, when it can be transmitted or not transmitted at a nominal, default, or regular position, based on, for example, one or more criteria. The criteria can be, for example, a function of when the WTRU can obtain access to the channel.

[0151] A WTRU can use a mini-slot (e.g., be configured to use) if it is possible for it to obtain access to a channel (e.g., for the first time). A WTRU can use flexible RS (e.g., DM-RS) transmission if it is possible for it to use a mini-slot for (e.g., the first) transmission.

[0152] RS (e.g., DM-RS) that can be associated with a mini-slot can be used by the eNB to determine a set of candidate resources (e.g., frequency resources) on which the WTRU can be transmitted. The RS can be used by the eNB (e.g., can also be used) to determine the start time of transmission.

[0153] A WTRU can use a slot (e.g., a regular slot) or a mini-slot based on, for example, the time when the WTRU can obtain access to a channel. In an example, the WTRU can determine to use a slot (e.g., a regular slot) for transmission if it can obtain access to a channel within a certain number of symbols, e.g., two symbols (e.g., OFDM or DFT-spread-OFDM (DFT-s-OFDM) symbols) from the start of a subframe. The subframe can include, for example, two slots. The WTRU can use at least one (e.g., the first) slot and can transmit, for example, in the symbols of the slot that occur after the WTRU has obtained access to the channel. The WTRU can transmit RS at its nominal, regular, or default location if that location can be (e.g., is) included within the transmission symbol (e.g., the fourth symbol of the slot).

[0154] In another example, the WTRU may use a mini-slot for its first transmission if, for example, the WTRU can obtain access to the channel after a certain number of symbols (e.g., 4 symbols) from the start of the subframe, or if the WTRU can obtain access to the channel after the nominal, regular, or default position of the RS. The WTRU may transmit the RS in one or more symbols of the mini-slot according to a mini-slot configuration that can be received, determined, and / or indicated.

[0155] The eNB can determine a set of candidate sets that can be used, for example, based on the start and / or end point or time of the transmission. The eNB can blindly detect the start and / or end point. The eNB can receive an indication from the WTRU to assist it in determining the start and / or end point of the transmission, for example.

[0156] The DM-RS can be transmitted at the end time of the transmission (e.g., in one or two last symbols). The frequency resources for DM-RS transmission can be the same regardless of the frequency resource candidates that can be determined for the transmission. In an example, the nominal bandwidth for the transmission can be used for DM-RS transmission. The nominal bandwidth can be, for example, a frequency resource candidate that can be used with respect to a reference start time and / or duration (e.g., time period).

[0157] One or more sequences can be used for the DM-RS. The number of sequences used can be determined, for example, based on the number of frequency resource candidates. One (e.g., each) sequence can correspond to one frequency resource candidate.

[0158] A sequence corresponding to a frequency resource candidate can be used for transmission, for example, when an eNB, gNB, or WTRU can determine a frequency resource candidate, for example, based on the start and duration of transmission.

[0159] The receiver can detect (e.g., indiscriminately) the sequence of DM-RS transmitted at the end of transmission to determine, for example, the frequency resource candidate used.

[0160] For example, if the determined frequency resource may be wider than the nominal frequency resource, one or more (e.g., additional) DM-RS in frequency can be used.

[0161] For example, if the duration may be longer than the reference duration (e.g., time period), one or more (e.g., additional) DM-RS in time can be used.

[0162] The DM-RS can be transmitted (e.g., alternatively) at the end time of transmission, and it can be aligned regardless of the frequency resource candidate. The frequency resources for the DM-RS can be different, for example, based on the frequency resource candidate. In an example, the DM-RS can be transmitted in the frequency resource. The DM-RS sequence and / or sequence length can be determined, for example, based on the determined number of frequency resources. The receiver can detect the DM-RS sequence (e.g., indiscriminately) to determine the frequency resource candidate used for transmission.

[0163] It is possible to provide a maximum power constraint. The WTRU may exceed the maximum power (e.g., the maximum output power configured) when using additional frequency resources, for example. The WTRU can take one or more actions to avoid violating the power constraint, such as by exceeding the maximum power or the maximum EIRP, for example.

[0164] The WTRU can limit candidates, for example, (when determining a set of frequency resources for use) to avoid exceeding the maximum power or EIRP, for example. The WTRU can adjust the power of one or more channels to be transmitted (alternatively, for example) to avoid exceeding the maximum power or EIRP, for example.

[0165] The eNB can use the latest power headroom report to determine the set most likely to be used in transmission, for example, (for the purpose of blind decoding frequency resources).

[0166] The WTRU can determine a set of frequency resources for use in transmission. For example, if the WTRU may use a set of frequency resources that may result in exceeding the maximum power (e.g., for a short transmission), the WTRU can act as if the channel has been determined to be busy and check the availability of the channel at the start of a subsequent (e.g., next) time period.

[0167] In an example, the WTRU can perform CCA for a first time unit whose transmission time can be Tbase (e.g., within a time period). For example, if the WTRU can determine that the channel is free, the WTRU can use a first set of frequency resources for transmission. For example, if the WTRU can determine that the channel is busy, the WTRU can try again in a second time unit (e.g., within the time period) whose transmission time can be Tshort (in this case, Tshort < Tbase). For example, if the WTRU can determine that the channel is free, the WTRU can use a second set of frequency resources for transmission (e.g., the second set of resources can include more resources than the first set of resources).

[0168] For example, if the WTRU determines that transmission on the second set of frequency resources may violate (e.g., will violate) a power constraint (e.g., maximum power or EIRP), the WTRU can skip the transmission for the second time unit (e.g., starting at the second time unit). The WTRU can try again (e.g., perform CCA and transmission if the channel is free) for a subsequent (e.g., next) time unit within the time period, or try again for a subsequent (e.g., next) time period. The WTRU can result in (e.g., by proceeding to a subsequent time period) the WTRU having more time for transmission and using fewer frequency resources that do not exceed the maximum power.

[0169] The WTRU can determine that transmissions on a second set of frequency resources may violate transmission power constraints. The WTRU can search for (e.g., alternatively) a smaller TBS and / or a lower modulation order that can enable the WTRU to meet the transmission power constraints (e.g., among one or more candidates) and / or determine such. The WTRU can perform transmissions using the TBS and modulation order. The TBS can be, for example, the initial TBS or the determined smaller TBS. The modulation order can be, for example, the initial modulation order or a lower modulation order. One or more candidate TBSs and modulation orders can be pre-defined or configurable. DM-RS that can be transmitted in the frequency resource can be used, for example, to indicate which TBS and / or modulation order can be used.

[0170] The time unit can be, for example, a scheduled, configured, or allocated time unit. The time period can be, for example, a scheduled, configured, or allocated time period.

[0171] The WTRU can request a channel, for example, for a duration of Tshort, until the start of a subsequent (e.g., next) time period and / or until it can perform transmissions and / or use fewer frequency resources during a longer period of time. The WTRU can transmit a reference signal or other signal, for example, within the first or second set of frequency resources, to request a channel. The WTRU can perform transmissions in the next time period (e.g., at the start of the next time period).

[0172] Beam sweeping adaptation can be provided. The WTRU can perform UL Tx beam sweeping operations and / or retransmissions, for example, to enable UL Rx beam sweeping operations (e.g., when transmitting in an unlicensed channel or band). Retransmissions can include, for example, repetitions (e.g., of the same data). Retransmissions can include, for example, multiple transmissions on the same Tx beam or in the same direction. The multiple transmissions can be the same (e.g., the same data) or not. The WTRU and / or gNB can have a limit on the number of beams that can be used simultaneously. The WTRU can repeat transmissions over multiple symbols. In an example, the WTRU can transmit a TB over a symbol and repeat the transmission over multiple symbols (e.g., of a slot). The repetition can enable, for example, Tx and / or Rx beam sweeping or be used for them. The number of symbols of a transmission that can be part of a set of repeated transmissions can be constant. In an example, the number of symbols can be the same for one or more (e.g., all) of the transmissions in the set of repeated transmissions.

[0173] The WTRU can select a subcarrier spacing, for example, based on the amount of time remaining in the transmission opportunity or based on the time when the WTRU may have acquired the channel. The WTRU can be configured with a set of subcarrier spacing values that can be applicable for transmissions in the channel.

[0174] The overall transmission bandwidth can have limitations (e.g., due to maximum power constraints). The WTRU can reduce the symbol time (e.g., by increasing the subcarrier spacing) until the maximum bandwidth is achieved. The WTRU can modify the rate at which it can repeat transmissions. In an example, the WTRU can map a complete TB to a symbol (e.g., for a first subcarrier spacing) and repeat the transmission over adjacent symbols (e.g., while changing its UL transmission beam). The WTRU can map a complete TB to a set of one or more symbols (e.g., two symbols) (e.g., for a second subcarrier spacing) and repeat that set of symbols over adjacent symbol sets. This can reduce the number of beams over which the WTRU can sweep transmissions. The WTRU can adapt the beamwidth of each individual beam over which it can repeat the transmission of data (e.g., each) to enable the WTRU to sweep over an appropriate total beamwidth. The adaptation can be based on the total number of repetitions available in the transmission opportunity.

[0175] Adaptation of the data size can be provided. In an example, the transport block size (TBS) can be adapted. The TBS can be the same for one or more (e.g., all) candidate sets of resources. One (e.g., each) candidate set of resources can be associated (e.g., alternatively) with a TBS. The WTRU can, for example, use the associated TBS to perform transmissions on a set of resources (e.g., a set determined from the candidates).

[0176] The WTRU and / or eNB can determine the amount of data to be transmitted (e.g., TBS) based on, for example, the start point or start time of transmission, the end point or end time of transmission, and / or the duration of transmission. The amount of data (e.g., TBS) can be determined using, for example, the number of PRBs in the resource set used for transmission, based on a candidate set of resources (e.g., frequency resources) used for transmission.

[0177] The WTRU may not have sufficient time to construct or reconstruct the TB before transmission if, for example, the size of the WTRU may change depending on when the WTRU can start transmission.

[0178] The WTRU can prepare a set of transport blocks having sizes corresponding to one or more possible start times, durations, and / or frequency resource sets. The WTRU can use the prepared TBs that can be aligned with the (e.g., autonomously) determined start time, duration, and / or frequency resource set.

[0179] For example, code block segmentation can be used if it may not be the optimal solution to prepare multiple TBs in advance. The number of code blocks for transmission can be determined based on, for example, the time available for transmission.

[0180] In an example, the WTRU can determine the number of code blocks for transmission based on, for example, the start point or start time of transmission, the end point or end time of transmission, and / or the duration of transmission. The number of code blocks can be determined and / or selected by the WTRU from, for example, a candidate set or a configured set.

[0181] The receiver (e.g., eNB) can determine the number of code blocks to be transmitted based on, for example, the start point or time of transmission, the end point or end time of transmission, and / or the duration of transmission.

[0182] The WTRU may not be able to transmit all the code blocks (CBs) of a transport block (TB) in a transmission opportunity (e.g., a slot). The WTRU can hold (e.g., all) the CBs of the TB (e.g., transmitted and non-transmitted), for example, if retransmission of the CB or CB group (CBG) may be possible, and wait for the gNB to provide HARQ feedback (e.g., CBG-level HARQ feedback) or a CBG-level UL grant to transmit the remaining CBs.

[0183] In an example (e.g., an alternative example), the WTRU can adapt the TB transmission to fit into a plurality of (e.g., two) adjacent minislots (e.g., TB segmentation through a plurality of slots or minislots). The first minislot size can be adapted to include, for example, a first set of CBs that can be transmitted from the time the WTRU can acquire the channel to the transmission boundary. The second minislot size can be adapted to enable the transmission of the remaining set of CBs (e.g., through a pre-determined bandwidth). The second minislot can be transmitted, for example, immediately after the transmission of the first minislot (e.g., if the MCOT may not be exceeded). The WTRU can then transmit a subsequent TB (e.g., upon completion of the transmission of the second minislot for the first TB), which can be transmitted over a default, pre-configured, or pre-determined slot size (e.g., if the MCOT may not be exceeded). In an example (e.g., an alternative example), the slot size used by the WTRU for the remainder of its channel occupancy can be a function of the slot sizes that can be used in the first and / or second minislot transmissions.

[0184] In an example (e.g., an alternative example), the WTRU can be configured to use minislots, for example, when it first accesses a channel, and can then return to using slots (e.g., regular slots) for subsequent back-to-back transmissions. The WTRU can determine whether to use a minislot or a slot, for example, based on the transmission start point (e.g., if the channel can be determined to be available). The WTRU can determine the size of the minislot (e.g., two, three, four symbols), for example, based on the transmission start point.

[0185] In an example (e.g., an alternative), the WTRU can divide the TB to be transmitted into a plurality of (e.g., two) codewords. The WTRU can determine to transmit a plurality of codewords, shorter codewords, or longer codewords, for example, based on the transmission start point and / or the transmission duration.

[0186] The WTRU can be permitted UL resources to transmit another TB in a second slot (e.g., in grant-based transmission). The WTRU can prevent, for example, in this case, using a mini-slot, for example, from transmitting a second TB to complete the transmission of a first TB. The prevention can lead to, for example, the second TB transmission including segmentation into a plurality of (e.g., two) mini-slots and / or preventing a third TB transmission.

[0187] The WTRU can include DM-RS and / or another reference signal in one (e.g., each) slot, for example, regardless of the slot size, if one or more TBs can be segmented over a plurality of mini-slots. In an example (e.g., an alternative), the WTRU can include one or more (e.g., all) reference signals in one or more slots (e.g., only those slots) for a transmission with one or more segmented TBs. Including the reference signal can be configured statically or quasi-statically (e.g., together with grant-free transmission configuration), can be determined by the WTRU, and / or can be indicated to the gNB.

[0188] It is possible to provide adaptation of the control channel. The type or size of the UL control channel (e.g., PUCCH) can depend on, for example, the amount of time available for transmission, such as PUCCH alone or in combination with PUSCH transmission. The PUCCH can be repeated in time and / or frequency, for example, to improve the coverage of the PUCCH.

[0189] Resources for PUCCH transmission and / or repetition can be selected and / or determined from a set of candidate resources that can be configured. The resource set can be selected and / or determined, for example, based on the time available for transmission.

[0190] The PUCCH type can (e.g., alternatively) depend on, for example, the amount of time available for transmission. In an example, a first PUCCH type (e.g., DM-RS-based PUCCH) can be used for a first set of candidate resources, and a second PUCCH type (e.g., sequence-based PUCCH) can be used for a second set of candidate resources. The first set of candidate resources can have a longer duration than the second set of candidate resources. One or more of the following can apply. The first PUCCH type (e.g., DM-RS-based PUCCH) can provide a higher multiplexing capacity, while its performance may be worse than that of the second PUCCH type (e.g., sequence-based). The second PUCCH type can provide better performance, while providing a lower multiplexing capacity. The sets of candidate resources for the first and second PUCCH types can be non-overlapping in frequency.

[0191] The content of PUCCH transmission can change, for example, due to the determination that the channel is busy, based on, for example, a delayed start of PUCCH transmission. In an example, for example, if the transmission can start in a first time unit or time period, the first content can be transmitted. For example, if the transmission may be delayed to a second time unit or time period due to the determination that the channel is busy with respect to the first time unit or time period, the second content can be used.

[0192] In an example, the second content can include ACK / NACK (A / N) information regarding more DL transmissions than the first content. The second content can include A / N information regarding more DL transmissions, for example, if the time window covered by the delayed PUCCH can cover A / N for more DL transmissions.

[0193] In an example, the first content can include A / N regarding the first, second, and third DL transmissions. The second content can include A / N regarding the first, second, third, and fourth DL transmissions. The fourth A / N information can be included, for example, if the delay from the first time unit or period to the second time unit or period with respect to the HARQ timing for DL transmission can ensure adding A / N information regarding another possible DL transmission.

[0194] In another example, the first content may include A / N and CQI. The second content may include A / N without CQI, for example. CQI may be dropped based on, for example, the time available for transmission. CQI may be dropped, for example, when there may be no room to transmit CQI on the PUCCH, such as when the PUCCH may be shortened. The PUCCH may be shortened based on, for example, the time available for transmission, which may be a function of when the channel is determined to be free for transmission.

[0195] A transmission time start point may be configured. The WTRU may be configured with a set of transmission start points that may correspond to, for example, time units or time periods. The time unit may be within one or more time periods. In an example, the WTRU may be configured with a set of symbols that may be within the subframe in which the WTRU may perform or start transmission.

[0196] A set of time units (e.g., symbols) within a time period (e.g., subframe) in which the WTRU may start transmission may be configured. The configuration may be provided by higher layer (e.g., RRC) signaling. The configuration may be provided in DCI. The DCI may include a UL grant for transmission. The DCI may be common DCI, for example, it may be intended for one or more WTRUs or may be used by one or more WTRUs. The DCI may include a trigger, for example, to enable UL transmission, after, for example, grant parameters are provided (e.g., individually).

[0197] The WTRU may determine that the channel may not be clear before the first starting point (e.g., for grant-based or grant-less access). The WTRU may try again for one or more (e.g., each) of the next starting points in the set of starting points, for example, until the WTRU can determine that the channel is free for transmission. The WTRU may transmit (e.g., starting at the starting point), for example, if the WTRU can determine that the channel is free for the starting point.

[0198] The transmission time can be shortened. The end of the transmission in a time period can be fixed or configurable. In an example, the transmission can end at the last time unit of the time period or at another configured time unit within the time period.

[0199] The amount of time available for transmission can be, for example, a function of the starting point of the transmission in a time period.

[0200] In an example, a transmission starting at a first time unit in a time period may result in a T1 time for transmission, and a transmission starting at a second time unit in the time period may result in a T2 time for transmission. For example, if the second time unit may be after the first time unit, T2 may be less than T1. For example, if CCA may fail for the first time unit and pass for the second time unit, such that the WTRU begins transmitting for the second time unit, the WTRU may have even less time to transmit (e.g., T2 time instead of T1 time).

[0201] The transmission time (e.g., maximum transmission time) can be fixed or configured. The transmission time can be, for example, the length of a time period, a TTI, which can be configured or the time or TTI that is scheduled, permitted, or allocated for transmission.

[0202] The transmission time can start in a time unit, and the transmission time can be relative to the start time unit if, for example, the WTRU can start transmission in a time unit that may not be at the start of a time period. Transmission can continue in the next time period if, for example, the transmission time can be longer than the time from the time unit to the end of the time period.

[0203] The WTRU and / or eNB can determine the number of transport blocks that can be transmitted. The number of transport blocks that can be transmitted can be, for example, a function of the start point or time and / or end point or time of transmission.

[0204] The WTRU can be allocated or permitted n or up to n time periods, TP1, TP2,..., TPn. The WTRU can perform CCA. CCA can start before TP1. The WTRU can determine that the channel is free for transmission starting in time unit x, TUx, within time period k, TPk.

[0205] The WTRU can transmit a first transport block (TB) starting at TUx. The WTRU can determine the number, B, of transport blocks that it can transmit. For example, the WTRU can transmit up to B transport blocks (B≦N). In an example, B can be the number of transport blocks (e.g., complete transport blocks) that can be transmitted in a time period starting at TUx and ending at the end of TPn. The WTRU can, for example, release the channel after transmitting B transport blocks. The WTRU can, for example, release the channel before transmitting B transport blocks if there is a possibility that the WTRU has completed transmitting data or a TB.

[0206] For example, if there is a possibility that the transmission of the first TB does not start (e.g., does not start) at the beginning of the time period, the first TB can have its size reduced (e.g., such that the transmission of the first TB can fit within the first time period). The remaining TBs that can be transmitted can be of full size. The first TB and one or more subsequent TBs can (e.g., alternatively) be of full size, and the last TB can have its size reduced, for example, to fit within the last part of the last time period that can include the transmission.

[0207] The amount of data that the WTRU can transmit, such as the transport block size (TBS), can be a function of the start point and / or end point of the transmission.

[0208] In an example, the WTRU can perform CCA for transmissions at the start of symbols within an SF. The WTRU can try again in subsequent symbols within the SF (e.g., if there is a possibility that the CCA may fail). The WTRU can start and perform a transmission in subsequent symbols, for example, if the WTRU can determine that the CCA is successful.

[0209] For example, if the WTRU can try again in a subsequent time unit (e.g., symbol), a full CCA can be used. The full CCA can be not a new CCA. The full CCA can be a continuation of a full CCA that may have been performed prior to the previous time unit (e.g., symbol). In an example, the WTRU can perform a (e.g., full) CCA and, following a determination that the channel may be free, can start a transmission in the first symbol within the permitted or allocated time resources.

[0210] It can be possible to provide an indication of a start time and / or an end time, which can be detected, for example, by blind decoding. The eNB can use blind decoding or assistance from the WTRU's transmission, for example, to receive and / or decode a transmission that can have one or more flexible boundaries or patterns in time and / or frequency.

[0211] In an example, the eNB can determine (e.g., based on blind detection) the start and / or end of a transmission that it can receive. Blind detection can include, for example, attempting to receive and / or decode one or more candidate transmission sizes. A transmission can be considered successfully received and / or decoded, for example, if it is determined that the CRC is correct. The transmission size can include, for example, the number of time units and / or time periods. A candidate can include, for example, a time component and a frequency component for a transmission where the number of frequency resources and / or pattern can be adapted, for example, based on the length of the transmission in time.

[0212] The WTRU can provide indication and / or assistance. In an example, a reference signal can be transmitted and / or used to indicate the start and / or end of a transmission.

[0213] In an example, the WTRU can transmit a first reference signal, for example, to indicate the start of a transmission. The WTRU can transmit a reference signal in at least one time unit of the transmission. In an example, the reference signal can be transmitted in the (e.g., at least) first time unit of the transmission.

[0214] The WTRU can transmit a second reference signal, for example, to indicate the end of a transmission. The WTRU can transmit a reference signal in one (e.g., at least one) time unit of the transmission. In an example, the reference signal can be transmitted in the (e.g., at least) last time unit of the transmission.

[0215] The WTRU can transmit a first and / or second reference signal regarding a transmission. The first reference signal and the second reference signal can be the same or different.

[0216] The start, such as the start time of transmission (e.g., start time unit or time period), can be one of a set of starts that can be configured. The start time can be a start time unit within a time period.

[0217] The end, such as the end time of transmission (e.g., end time unit or time period), can be one of a set of ends that can be configured. The end time can be an end time unit within a time period.

[0218] For example, if the frequency resources that can be used for transmission may be a determined subset from a set of frequency resources, the reference signal can be transmitted in a bandwidth or pattern that can exist independently of the subset selected or used.

[0219] The reference signal can be transmitted, for example, repeatedly, over the bandwidth or pattern of a subset of the frequency resources that can be used for transmission (e.g., as an alternative).

[0220] In an example, the first subset can include a set or pattern of F1 frequency resources, and the second subset can include a set or pattern of F2 frequency resources. The F1 resources can be a subset of the F2 resources. When the WTRU performs transmission using, for example, the F1 resources, it can transmit a reference signal within the F1 resources. When the WTRU performs transmission using, for example, the F2 resources, it can transmit a reference signal within the F1 resources. (For example, an alternative) In an example, when the WTRU performs transmission using, for example, the F2 resources, it can refrain from transmitting a reference signal within a resource that can be within F2 but not within F1. In a (for example, alternative) example, when the WTRU performs transmission using, for example, the F2 resources, it can transmit a reference signal within a resource that can be within F2 but not within F1. The transmission can be a repetition or extension of the transmission within the F1 resources.

[0221] Transmission of a reference signal within a set or pattern of resources (e.g., F1 or F2) can be within a subset of the resources, for example, within a set of REs within the resource or RB.

[0222] A reference signal that can be used to indicate a time reference can be called a time reference signal (TRS).

[0223] The WTRU can include, for example, a control channel at the start of the transmission. The control channel can include, for example, an indication of the length or duration of the transmission (e.g., in time).

[0224] The location of the control channel in frequency can be based on, for example, the smallest set of frequency resources that can be used for transmission.

[0225] In an example, for instance, if the frequency resources that can be used for transmission may be a determined subset from a set of frequency resources, the control channel can be transmitted in a bandwidth or pattern that can exist independently of the subset that is selected or used.

[0226] The control channel can (e.g., also) indicate a set of frequency resources that can be used (e.g., a candidate set selected from a configured set of candidates).

[0227] The WTRU can perform or execute measurements that can be energy detection measurements, for example, when performing a channel assessment, for example, to determine whether the channel may be clear. The energy detection or measurement can be performed over a frequency band or set that can include one or more (e.g., all) candidate frequency sets. The WTRU can compare the measured value or detected energy to a threshold to determine whether the channel may be free or busy.

[0228] A candidate frequency set can be a subset of another candidate frequency set. A frequency set can include, for example, one or more (e.g., all) other candidate frequency sets. The maximum frequency set can include, for example, one or more (e.g., all) other candidate frequency sets.

[0229] The WTRU can perform a channel assessment with respect to a frequency band or set of frequency resources that can be the maximum frequency set or can include it.

[0230] The band or set of frequencies or frequency resources on which the WTRU is capable of performing CCA can be larger than the band or set of frequencies or frequency resources on which the WTRU is capable of transmitting.

[0231] The WTRU may not know (e.g., at the time it is capable of performing CCA) on which frequencies it is capable of transmitting (e.g., will transmit). In an example, the WTRU is capable of performing CCA for a first time unit in which there can be a time T1 for transmission. The WTRU can transmit on resource set R1 (e.g., during time T1). For example, if CCA is unsuccessful in the first time unit (e.g., if the WTRU determines that the channel is busy), the WTRU can determine whether the channel is free for transmission in the second time unit. For example, for a transmission that can start in the second time unit, there can be a time T2 for transmission (e.g., in this case, T2 can be less than T1). The WTRU can transmit on resource set R2 (e.g., during time T2). R2 can include more frequency resources than R1. R2 can span more frequencies than R1. R1 plus R2 can span more frequencies than R1.

[0232] The WTRU can perform CCA, for example, with respect to a band or set of frequencies that can include at least the frequency resources in set R1 and set R2, to ensure that, for example, the CCA backoff / standby time can be observed (e.g., is observed).

[0233] In an example (e.g., an alternative), the WTRU is capable of performing multiple energy detection measurements over a frequency band or set of frequencies that can include one or more candidate frequency sets. The multiple energy detection measurements (e.g., each of them) can be related to a subset of the band. In an example, the subsets can overlap and can be non - orthogonal. In another example (e.g., another alternative), one subset (e.g., each subset) can be disjoint and / or the set of all subsets can include the entire band. The WTRU can determine a channel access assessment value for each transmission bandwidth (e.g., at any given time) for transmission based on measurements over a subset of the band and (e.g., as required) the transmission bandwidth. In an example, the band can be segmented into n sub - bands on which the WTRU can obtain n energy detection measurement values. The WTRU can perform CCA by obtaining n energy detection measurement values on n sub - bands for a first time instance for which there can be a time T1 available for transmission. The WTRU may require a resource set R1 (e.g., for such a transmission). The WTRU can search over one or more (e.g., all) combinations of the n sub - bands that can form the R1 resource to determine whether any combination of sub - bands satisfies the clear channel assessment. The WTRU can limit the search, for example, to adjacent sets of sub - bands forming R1. The WTRU can limit the search to non - adjacent sets of sub - bands forming R1 (e.g., as an alternative).The WTRU is capable of obtaining n energy detection measurements on n sub - bands for a second time instance in which (e.g., if CCA may fail) there is a T2 time available for transmission and the transmission can use resource set R2, and thereby attempting CCA. The WTRU is capable of performing a search over one or more (e.g., all) combinations of the n sub - bands that can include the R2 resources to determine whether any combination of sub - bands can satisfy the clear channel assessment.

[0234] The WTRU can be configured to puncture out (e.g., not use or not measure) one or more sub - bands, for example, when the WTRU is capable of performing CCA. The sub - bands can be allocated or used for other WTRUs or other types of WTRUs. In an example, for unlicensed spectrum, N DL physical resource blocks (PRBs) can be used, determined, or configured. A subset of the N DL PRBs can be excluded from the energy detection. Sub - bands or PRBs for exclusion can be configured.

[0235] The subset of PRBs that can be punctured out of the CCA can be configured (e.g., via higher - layer signaling) or determined (e.g., based on a time period number, a time unit number, a cell ID, and / or a number of PRBs).

[0236] A subset of PRBs that can be punctured out from the CCA can be not used for transmission. In an example, the WTRU can be scheduled for uplink transmission, for example, and if one or more scheduled PRBs can overlap with a subset of PRBs that can be punctured out from the CCA, the WTRU can not send a signal in the subset of PRBs.

[0237] The energy threshold for determining whether a channel can be occupied can be based on, for example, the number of PRBs that can be punctured out from the CCA. In an example, an offset can be used for the energy threshold. The offset can be determined based on, for example, the number of PRBs that can be punctured out from the CCA.

[0238] The maximum allowed transmission power can be determined based on, for example, the number of PRBs that can be punctured out from the CCA.

[0239] The WTRU can perform CCA for one or more sets of frequencies. One (e.g., each) set of frequencies can be configured with a numerology, waveform, and / or transmission scheme.

[0240] One (e.g., each) set of frequencies can be configured with an energy threshold for CCA. The energy threshold can depend on the waveform that can be used in the set of frequencies.

[0241] The CCA capabilities of a WTRU can provide a flexible transmission boundary. WTRUs may have separate capabilities for performing CCA. A WTRU can, for example, have and / or report capabilities regarding the time granularity at which the WTRU can perform one or more (e.g., consecutive) CCAs.

[0242] A WTRU can have, provide, and / or report (e.g., to an eNB) its capabilities for performing CCA. The capabilities can indicate, for example, how often and / or on which time boundaries a WTRU may or may be able to perform CCA, e.g., in terms of time units or time periods.

[0243] In an example, a WTRU may or may be able to perform CCA with respect to a time unit boundary or a time period boundary (e.g., on which to start transmission).

[0244] A WTRU may or may be able to perform CCA with respect to adjacent or consecutive time unit boundaries. A WTRU may or may not be able to perform CCA with respect to adjacent or consecutive time unit boundaries.

[0245] A WTRU that may not be able to perform CCA with respect to adjacent or consecutive time unit boundaries can, for example, perform CCA once per time period. In an example, if a WTRU determines that the channel may not be clear during a time period (e.g., between time units of the time period), the WTRU can refrain from trying again until another or the next time period (e.g., between time units of another or the next time period).

[0246] A WTRU that is capable of supporting CCA for a time period (e.g., only supporting) can, for example, with respect to grant-based transmission, perform CCA for a time period (e.g., SF) and not perform CCA for a time unit (e.g., slot or symbol), or be scheduled to do so (e.g., only be scheduled).

[0247] A WTRU that is capable of supporting CCA for a time period (e.g., only supporting) can, for example, with respect to grant-free transmission, perform CCA for a time period (e.g., for one time unit per time period, such as for one symbol position per time period or SF) (e.g., only perform).

[0248] Performing CCA for a time period instead of a time unit may delay transmission but may allow the WTRU to sleep longer.

[0249] The time granularity at which a WTRU can perform CCA can, for example, depend on the numerology of the expected transmission. In an example, a WTRU that may be transmitting with a large subcarrier spacing performing CCA on adjacent or consecutive symbols may be unduly costly. The WTRU can be configured with a time granularity that can depend on the subcarrier spacing of the intended transmission or the default subcarrier spacing for the channel. The configuration can be provided, for example, via a broadcast transmission (e.g., in a system information block) or via a group-specific or WTRU-specific configuration.

[0250] It is possible to determine whether a channel may be clear for transmission at a time boundary. The WTRU can perform CCA, for example, to meet CCA requirements, starting before the time boundary and / or during a plurality of time units and / or time periods before the time boundary.

[0251] The configuration can be provided, for example, by network nodes or elements such as eNB, gNB, TRP, and / or cells, among others. The WTRU can receive the configuration from a network node. The WTRU can receive the configuration, for example, via higher layer (e.g., RRC) signaling or broadcast signaling. The WTRU can receive the configuration, for example, via physical layer signaling such as in DCI. The configuration can be specific to, among others, the WTRU, cell, TRP, beam, and / or group of beams.

[0252] It is possible to provide a grant-free access resource pool. The resource pool can be used, for example, for grant-free transmission. The resource pool can be a set of resources (e.g., time resources and / or frequency resources) that can be used by one or more WTRUs for transmission. The WTRU can determine or select a subset of resources from the resource pool for use in transmission.

[0253] One or more resource pools can be configured and / or used by one or more WTRUs for grant-free transmission. The WTRU can receive the configuration of the resource pool that the WTRU can use for grant-free transmission.

[0254] For example, if a WTRU is capable of using a subset of resources, the WTRU can perform CCA on the subset of resources from a resource pool. For example, if a WTRU can be configured with one or more resource pools, the WTRU can perform CCA (e.g., alternatively) for each resource pool.

[0255] A resource pool can be configured, for example, with a time schedule or pattern. The schedule or pattern can be periodic. The schedule or pattern can be composed of a set of time units and / or time periods, such as consecutive time units, consecutive time periods, and / or a pattern of time units and / or time periods that can be repeated. The set of time units can be within a time period. The time unit, set of time units, or time period can be relative to a reference point that can be beam-specific. In an example, the reference point can be the start or end of a synchronization burst (e.g., an SS burst) or a synchronization block (e.g., an SS block) that can be within the synchronization burst.

[0256] The repetition can be periodic. The repetition can have a duration after the repetition can end. The repetition can continue, for example, until further configuration indicates that the repetition can end (e.g., will end) or is no longer used.

[0257] A resource pool that can be configured with a time schedule or pattern can be referred to as a semi-persistent scheduling (SPS) configuration.

[0258] A resource pool can be configured with one or more sets of resources that can include time resources and / or frequency resources. The resources can be resource blocks (RBs) or physical resource blocks (PRBs). The resources can be continuous in frequency (e.g., contiguous subcarriers). The resources can be dispersed in frequency, e.g., across a frequency band or sub-band.

[0259] The use of SPS can mean that some resources can be UL-exclusive and not used for DL. This implication may not hold, for example, in scenarios using CCA. An eNB capable of performing DL transmissions can perform CCA, for example, before the start of a time unit or time period (e.g., SF) in which there may be configured SPS resources. The eNB can select or use a channel for DL transmission, for example, if the CCA is successful. For example, if the WTRU's CCA occurs after sufficient time has elapsed after the eNB has been able to start transmission, the WTRU can consider the channel busy and not transmit in UL.

[0260] The WTRU can adjust its UL timing, for example, based on the received DL timing. The WTRU can transmit a timing advance (TA) value before the corresponding received time unit or time period (e.g., for UL time unit or time period transmissions).

[0261] The eNB can consider the cell size and / or TA, for example, when determining when to perform CCA and when to start transmission.

[0262] In an example, a cell size of 10 km can correspond to a timing advance of about 67 μs. A symbol can correspond to, for example, about 67 μs. The eNB can perform CCA, for example, to start transmitting at least a symbol before the start of a resource pool, for the purpose of enabling a WTRU (e.g., including a WTRU at the cell edge) within the cell to consider the channel busy before the start of the resource pool.

[0263] A resource pool can be configured with frequency resources (e.g., a set of RBs or PRBs) in a time unit or time period. One or more frequency resources can be used for one or more resource pools. The frequency resources for a resource pool can be orthogonal to the frequency resources for another resource pool. The frequency resources for a resource pool can partially or fully overlap with the frequency resources for another resource pool.

[0264] A set of frequency resources can be configured for grant-free access. The frequency resources from the configured set of frequency resources for a resource pool can be determined, for example, based on a resource pool ID, a cell ID, a time unit number, and / or a time period number.

[0265] The frequency resources for a resource pool can be changed from a first time resource to a second time resource (e.g., a time unit, a time period, or a slot).

[0266] A WTRU can perform CCA on the frequency resources associated with a resource pool. The frequency resources can be changed, for example, based on a time unit number, a time period number, and / or a slot number.

[0267] Allocation of resource pools and identification of WTRUs can be provided. In an example, one or more resource pools can be configured and / or used.

[0268] A resource pool can be configured for a group of WTRUs. A WTRU can be configured with or allocated to a group and / or a resource pool. The eNB can perform the grouping. The eNB can inform the WTRU of the group it can be in. In an example, a WTRU can be configured with the group it can be in. The configuration can include a group ID. The WTRU can determine the resource pool for use, for example, based on its group or group ID.

[0269] A WTRU can be configured (e.g., allocated means) to indicate its identity in its transmission. The indication of the identity can be used within a group. In an example, a first indication that can be used by a WTRU to identify itself in a first group can be used by a second WTRU to identify itself in a second group. A WTRU can be distinguished by the eNB, for example, based on the resource pool used by the WTRU for transmission.

[0270] A WTRU can use a CRC mask, for example, to identify itself when it performs a transmission. The mask can be configured by the eNB. The WTRU can mask (e.g., scramble) the CRC of its transmission using the mask. The mask can be, for example, an RNTI. The mask can be the C-RNTI of the WTRU, or a part or function of the C-RNTI of the WTRU. The mask can be received or configured, for example, individually from the C-RNTI of the WTRU.

[0271] In an example, the WTRU can receive a first RNTI for permitted access (e.g., its C-RNTI), and a second RNTI for grant-free access. The mask or RNTI for grant-free access can be a different number of bits than the RNTI or CRC mask for permitted transmission. In an example, the RNTI for permitted transmission can be used to mask the CRC of DCI, which can be intended for the WTRU, for example, for the purpose of providing a grant.

[0272] The WTRU can use a CRC mask to identify whether (e.g., alternatively) the WTRU buffer may be empty or may not be empty. In an example, a first CRC mask can be used (e.g., if the transmission may be the last transmission), and a second CRC mask can be used (e.g., if there may be subsequent transmissions).

[0273] The WTRU can use, for example, a WTRU-specific scrambling ID for the DM-RS sequence. In an example, the DM-RS sequence can be scrambled, for example, based on the WTRU-ID. The eNB (or gNB) can detect the DM-RS sequence (e.g., indiscriminately) to identify the WTRU, for example.

[0274] A resource pool layer can be provided. There can be a set of resource pools, for example, resource pools configured by SPS. The set of resource pools can have separate frequencies of occurrence or repetition. The resource pool of the first layer, for example, layer 1, can occur at a lower frequency than the resource pool of the second layer, for example, layer 2.

[0275] In an example, the resource pool of layer 1 can have a first occurrence or repetition frequency (e.g., every N1 time periods). The resource pool of layer 2 can have a second occurrence or repetition frequency (e.g., every N2 time periods). In an example, the resources of layer 1 can occur or repeat at a lower frequency than the resources of layer 2. In an example, N2 can be less than N1 (e.g., the second layer of resources can repeat at a higher frequency than the first layer of resources).

[0276] The selection or use of the resource pool of the first layer or the resources of the second layer for transmission can be based on, for example, the availability of the channel. In an example, the WTRU can try (e.g., first) to use one or more resources in the resource pool of the first layer. For example, if the WTRU determines that the channel may be busy (e.g., for more than a threshold number of times while trying to use the first resource pool), the WTRU can use or try to use one or more resources of the resource pool of the second layer.

[0277] In an example, the WTRU can start with a resource pool of a first layer, for example, layer 1. The WTRU can determine the occurrence or allocation of future layer 1 resources on which the WTRU can perform transmissions. The occurrence or allocation of the future resources can include a set of time units and / or time periods (e.g., n time periods). The WTRU can perform CCA, for example, prior to a first time period. The WTRU can determine whether the channel might be free for transmission in the first time period. The WTRU can perform a transmission, for example, in (at least) the resources in the first time period if the channel might be free. The WTRU can determine whether the channel might be free during one or more of the subsequent n - 1 time periods in the occurrence or allocation of resources (e.g., if the channel might not be free). The WTRU can perform a transmission starting from the first time period in which it can be determined that the channel is free.

[0278] The WTRU can try again in a subsequent (e.g., next) occurrence of the resource pool (e.g., if the channel might be busy for all time periods).

[0279] The WTRU might not be able to perform a transmission using the resource pool of the first layer for a threshold number N of attempts, for example, based on a determination that the channel might be busy. The WTRU can try to perform a transmission using resources in a resource pool of a second layer, for example, a more frequent resource pool. N can be the number of occurrences of the resource pool of the first layer. N can be the number of time units or time periods. The value of N can be configurable.

[0280] One or more resource pools or a set of resource pools can be configured and / or used. The resource pool or set of resource pools can be configured with priorities. Separate resource pools or sets of resource pools can have separate priorities or be configured with separate priorities. In an example, a first layer of resource pools, e.g., layer 1, can have a higher priority or be configured with a higher priority than a second layer of resource pools, e.g., layer 2. A WTRU can use (e.g., determine to use) a resource pool for transmission, e.g., based on the priority or type of the transmission.

[0281] In an example, the first layer of resource pools can be used for higher priority data or signal types (e.g., UCI, URLLC), while the second layer of resource pools can be used for lower priority data or signal types (e.g., data, eMBB, mMTC).

[0282] In an example, the first layer of resource pools can be used for retransmission of data channels, while the second layer of resource pools can be used for initial transmission, e.g., and vice versa.

[0283] For example, if a WTRU can be configured, determined, or indicated to transmit signals in a first layer of resource pools and a second layer of resource pools, the WTRU can transmit signals in multiple resource pools (e.g., if the uplink transmission power is not limited). The WTRU can drop or scale down signals for a second layer (e.g., lower priority) resource pool, e.g., if the uplink transmission power can be limited (e.g., is limited).

[0284] The resource pool of the first layer can be configured with an energy detection threshold lower than the energy detection threshold for the resource pool of the second layer, and vice versa. In an example, for example, an offset for the energy detection threshold for the resource pool of the second layer can be provided in relation to the energy detection threshold for the resource pool of the first layer.

[0285] Figure 2 is an example of a resource pool layer. The resource pool of layer 1 can include, for example, a set of n1 opportunities (e.g., every N1 time periods). The resource pool of layer 2 can include, for example, a set of n2 opportunities (e.g., every N2 time periods). The value of N2 can be smaller than the value of N1. The value of N1 and the value of N2 can be the same or can be different. An opportunity can be a transmission opportunity. An opportunity can include, for example, a set of time resources and / or frequency resources (e.g., RB or PRB). A transmission opportunity can include a set of transmission opportunities. The transmission opportunities of the resource pool can occur periodically or cyclically. In an example, the transmission opportunities of the resource pool of layer 1 can occur every N1 time periods. The transmission opportunities of the resource pool of layer 2 can occur every N2 time periods.

[0286] Opportunities within a transmission opportunity or opportunities within an opportunity set may be adjacent or contiguous in time, or may not be. An opportunity may correspond to one or more time units and / or time periods. Opportunities within a transmission opportunity or within an opportunity set may correspond to the same duration or amount of time, or may not. A WTRU may perform CCA at the start of an opportunity, at one or more subsequent times during the opportunity, at the start of a transmission opportunity, and / or at one or more subsequent times during the transmission opportunity. An occasion may include, for example, an opportunity and / or an opportunity. An opportunity and an occasion may be the same.

[0287] Figure 3 is an example of the selection and use of resource pool layers. In this example, for instance, if the WTRU determines that there may be a possibility that it could not determine that the channel was clear for a number of opportunities in the first resource pool layer, the WTRU can attempt to use the second resource pool layer (e.g., decide to do so).

[0288] Figure 4 is an example of the selection and use of resource pool layers. For example, if the WTRU determines that there may be a possibility that it could not determine that the channel was clear for a number of opportunities in the first resource pool layer, the WTRU can attempt to use the second resource pool layer (e.g., decide to do so).

[0289] It is possible to provide a switch to grant - based access. For example, if the WTRU may not be able to transmit grant - free resources (e.g., of layer 1 and / or layer 2) (e.g., due to a decision that the channel may be busy), the WTRU can request grant - based resources and / or licensed resources. For example, if the WTRU cannot perform a transmission using grant - free resources during a threshold number of attempts, the WTRU can make a request. A number of attempts can include, for example, a number of layer 1 attempts and / or a number of layer 2 attempts.

[0290] The WTRU can request grant - based resources and / or licensed resources, for example, by transmitting a scheduling request (SR) (i) on a licensed channel (e.g., on the PCell), (ii) on an unlicensed channel, and / or (iii) a PRACH on a licensed or unlicensed channel.

[0291] The SR can be transmitted on the allocated resources (e.g., the resources allocated to the PUCCH channel).

[0292] For example, for some types of communication (e.g., MTC), resource pooling may not occur frequently. In an example, resource pooling can occur several times a day. In an example, resource pooling can occur during a pattern of time periods that can occur once or multiple times a day.

[0293] For example, if the WTRU may not be able to use grant - free resources after a number of attempts, the WTRU can use PRACH resources that can occur more (e.g., even more) frequently.

[0294] FIG. 5 is an example of the selection and use of a resource pool layer. For example, if the WTRU determines that there may be a possibility that it cannot know that the channel is clear for a number of opportunities in the first resource pool layer, the WTRU can attempt to use the second resource pool layer (e.g., decide to do so). For example, if the WTRU determines that there may be a possibility that it cannot know that the channel is clear for a number of opportunities in the second resource pool layer, the WTRU can request a permitted or licensed resource (e.g., decide to do so).

[0295] FIG. 6 is an example of the selection and use of a resource pool layer. For example, if the WTRU determines that there may be a possibility that it cannot know that the channel is clear for a number of opportunities in the first resource pool layer, the WTRU can attempt to use the second resource pool layer (e.g., decide to do so). For example, if the WTRU determines that there may be a possibility that it cannot know that the channel is clear for a number of opportunities in the second resource pool layer, the WTRU can request a permitted or licensed resource (e.g., decide to do so).

[0296] Unlicensed operations can be provided in a beam-based system. A resource pool can be provided in a beam-based system. In an example, one or more resource pools can be used to support multiple beams. One (e.g., each) resource pool can be associated with a beam or a beam pair link (BPL).

[0297] One (e.g., each) resource pool can be configured with associated downlink signals that can be used, for example, to measure the quality of a beam. The measurement can be, for example, an RSRP measurement. The downlink signals that can be used for beam quality measurement can include, for example, beam discovery signals, beam reference signals, CSI-RS, SS bursts (e.g., SS in an SS burst), and / or SS blocks (e.g., SS in an SS block).

[0298] The resource pool for a beam or BPL can be configured in a periodic manner. In an example, the resource pool for a beam or BPL can be present, available, used, configured, or determined, for example, every T1 cycle or periodically with a time period of T1.

[0299] A WTRU can be configured with one or more beams or BPLs for grant-free access. One or more resource pools for the one or more beams or BPLs can be arranged, for example, in orthogonal time resources.

[0300] One or more SS blocks can be used in an SS burst. (E.g., each) SS block can be associated with one beam. The resource pool that can be associated with one beam (e.g., each) can be arranged in the (e.g., same) time resource with the SS block associated with that beam.

[0301] The WTRU can determine a resource pool that can be associated with a beam or beam pair link determined by the WTRU. In an example, the WTRU can measure the beam quality of SS blocks in an SS burst. The WTRU can determine the best or preferred beam (e.g., SS block), for example, based on the measurement of the beam quality. Signaling (e.g., broadcast signaling) can provide the associated resource pool for one (e.g., each) beam. The WTRU can use the determined resource pool associated with the beam or BPL for grant-free access.

[0302] The WTRU can indicate or otherwise inform the gNB of the beam (e.g., SS block) determined for grant-free access. The gNB can verify or configure the resource pool for use by the WTRU.

[0303] The gNB can provide the WTRU-ID (e.g., C-RNTI), for example, to the WTRU, for use in grant-free access in a beam-specific resource pool.

[0304] The WTRU can attempt grant-free access in the resource pool. For example, if the WTRU may not be able to access the channel for the resource pool (e.g., over a pre-defined or configured number of times (e.g., N times)) or may not be able to successfully transmit using the resource pool, the WTRU can switch to another resource pool that can be associated with a different beam. Not being able to successfully transmit can include, for example, not being able to receive a confirmation (e.g., HARQ-ACK) from the gNB, for example, in response to the transmission.

[0305] CCA can be performed in a beam-based system. In an example, the WTRU can perform CCA with respect to one or more resource pools associated with one or more beams or BPLs (e.g., determined beams or BPLs). The WTRU can determine, for example, an Rx beam for use in performing CCA, based on, e.g., an Rx beam that the WTRU might have used for beam determination (if the WTRU is capable of performing CCA).

[0306] The WTRU can perform CCA with respect to a resource pool based on, for example, an Rx beam that might have been used when the WTRU determined a beam or BPL.

[0307] The WTRU can perform CCA with respect to a resource pool based on, for example, one (e.g., the best) Rx beam capable of providing the highest RSRP. The best Rx beam can correspond to a Tx beam that the WTRU can use to perform transmission using the resource pool.

[0308] The WTRU can perform CCA with respect to one or more (e.g., all) Rx beams. The energy level that the WTRU can use to determine channel occupancy can be based on, for example, the highest energy measured or sensed with respect to one (e.g., any) Rx beam.

[0309] The WTRU can perform CCA for one or more (e.g., all) Rx beams. The energy level that the WTRU can use to determine channel occupancy can be based on, for example, the average of the energy levels of one or more (e.g., all) Rx beams. Rx beam sweeping can be performed within a CCA duration (e.g., 4 μs, 9 μs, or 25 μs). Rx beam sweeping can be performed over multiple CCA durations.

[0310] The WTRU can determine, for example, that the channel is clear after beam sweeping. The WTRU can perform CCA (e.g., a short CCA such as a 25 μs duration) using, for example, an Rx beam corresponding to a Tx beam on which the WTRU can transmit (e.g., will transmit) immediately before transmission to ensure that the channel is likely (e.g., is) clear in that direction before transmission. The WTRU can transmit if, for example, the WTRU determines that the channel is clear. The WTRU cannot transmit if, for example, the WTRU determines that the channel is not clear.

[0311] Systems, methods, and means for transmission compliance and license - free access in an unlicensed band have been disclosed. A flexible transmission boundary can be provided for transmission compliance. A license - free access resource pool can be provided. License - free operations can be provided in a beam - based system, for example, using a resource pool and / or CCA.

[0312] Features, elements, and actions (e.g., processes and means) are described by way of non-limiting examples. The examples may be directed to LTE, LTE-A, New Radio (NR), or 5G protocols, but the subject matter herein is applicable to other wireless communications, systems, services, and protocols. Each feature, element, action, or other aspect of the described subject matter, whether presented in a figure or in the description, can be implemented alone or in any combination with other subject matter, in any order, etc., regardless of whether known or unknown, and regardless of the examples presented herein.

[0313] The WTRU can refer to a physical device identity or a subscription-related identity, e.g., a user identity such as an MSISDN, SIP URI, etc. The WTRU can refer to an application-based identity, e.g., a username that can be used for each application.

[0314] The processes described above can be implemented by a computer program, software, and / or firmware incorporated into a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted via a wired connection and / or a wireless connection), and / or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, magnetic media such as ROM, RAM, registers, cache memory, semiconductor memory devices, internal hard disks, and removable disks, magneto-optical media, and / or optical media such as CD-ROM disks and / or DVDs. A processor associated with software can be used to implement a radio frequency transceiver for use in a WTRU, a terminal, a base station, an RNC, and / or any host computer.

Claims

1. A wireless transmit / receive unit (WTRU) comprising a processor, wherein the processor is configured to receive downlink control information (DCI) indicating a set of frequency resources, the DCI indicating a first start time associated with a first transmission opportunity and a second start time associated with a second transmission opportunity; determine that an attempt to access a channel for the first transmission opportunity associated with the first start time indicated by the DCI has failed; determine that an attempt to access a channel for the second transmission opportunity associated with the second start time indicated by the DCI has succeeded; transmit an uplink transmission at the second transmission opportunity associated with the second start time using the set of frequency resources indicated by the DCI based on the fact that the attempt to access the channel for the second transmission opportunity associated with the second start time has succeeded; a WTRU configured to perform the above.

2. The WTRU of claim 1, wherein the first transmission opportunity is associated with a first transmission time period and the second transmission opportunity is associated with a second transmission time period.

3. The WTRU of claim 1, wherein a demodulation reference signal (DM-RS) is included in the last orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission.

4. The WTRU of claim 1, wherein a demodulation reference signal (DM-RS) is included in the first orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission.

5. The WTRU of claim 1, wherein the processor is configured to determine the number of transport blocks to transmit based on the fact that an attempt to access a channel for the second transmission opportunity associated with the second start time has succeeded.

6. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving downlink control information (DCI) indicating a set of frequency resources, the DCI indicating a first start time associated with a first transmission opportunity and a second start time associated with a second transmission opportunity; determining that an attempt to access a channel for the first transmission opportunity associated with the first start time indicated by the DCI has failed; Determining that an attempt to access a channel for the second transmission opportunity associated with the second start time indicated in the DCI has been successful; Transmitting an uplink transmission at the second transmission opportunity associated with the second start time using the set of frequency resources indicated in the DCI based on the fact that the attempt to access the channel for the second transmission opportunity associated with the second start time has been successful; A method comprising. **Claim 7** The method of claim 6, wherein the first transmission opportunity is associated with a first transmission time period and the second transmission opportunity is associated with a second transmission time period. **Claim 8** The method of claim 6, wherein a demodulation reference signal (DM-RS) is included in the last orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission. **Claim 9** The method of claim 6, wherein a demodulation reference signal (DM-RS) is included in the first orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission. **Claim 10** The method of claim 6, further comprising determining the number of transport blocks to transmit based on the fact that an attempt to access a channel for the second transmission opportunity associated with the second start time has been successful. **Claim 11** A wireless transmit / receive unit (WTRU) comprising a processor, wherein the processor receives downlink control information (DCI) indicating a set of frequency resources, the DCI indicating a first start time associated with a first transmission opportunity and a second start time associated with a second transmission opportunity; determining that an attempt to access a channel for the first transmission opportunity associated with the first start time indicated in the DCI has been successful; transmitting an uplink transmission at the first transmission opportunity associated with the first start time using the set of frequency resources indicated in the DCI based on the fact that the attempt to access the channel for the first transmission opportunity associated with the first start time has been successful; transmitting a second uplink transmission at the second transmission opportunity associated with the second start time using the set of frequency resources indicated in the DCI based on the fact that the attempt to access the channel for the first transmission opportunity associated with the first start time has been successful; A WTRU configured to perform

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