Method for contention window size adjustment in unlicensed spectrum

Abstract

The invention provides a method for contention window size adjustment in an unlicensed spectrum, and particularly provides a method and apparatus for communicating on an unlicensed frequency band. A method may include transmitting transport blocks in each of a plurality of time slots, and determining a Hybrid Automatic Repeat reQuest (HARQ) state for each of the transmitted transport blocks. The method may further include determining a weighting coefficient for each of the determined HARQ states, and calculating a weighted average of the HARQ states of the transmitted transport block based on the determined HARQ states and the weighting coefficients. The method may also include adjusting a Listen Before Talk (LBT) contention window size based on the calculated weighted average of the HARQ state.

Description

This application is a divisional application of Chinese patent application No. 202080025590.7, filed on February 13, 2020, entitled “Method for Adjusting Contention Window Size in Unlicensed Spectrum”, and the contents of the parent application are incorporated herein by reference. CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 805,126, filed February 12, 2019, and U.S. Provisional Application No. 62 / 908,220, filed September 30, 2019, the contents of which are incorporated herein by reference. Background Art

[0002] Channel access in unlicensed bands typically uses a listen-before-talk (LBT) mechanism or procedure. In the LBT procedure, a network node or WTRU may first detect a transmission being performed on a given channel before starting its own transmission. In some cases, the LBT procedure is forced regardless of whether the channel is occupied. In other cases, the transmission may be performed immediately after a short switching gap.

[0003] For frame-based systems, the LBT mechanism or process can be characterized by a clear channel assessment (CCA) time period (e.g., ~20μs), a channel occupied time period (e.g., minimum 1ms, maximum 10ms), an idle period (e.g., a minimum of 5% of the channel occupied time), a fixed frame period (e.g., equal to the channel occupied time plus the idle period), a short control signaling transmission time (e.g., a maximum duty cycle of 5% within a 50ms observation period), and a CCA energy detection threshold.

[0004] For load-based systems, such as those in which the transmit / receive medium may not be fixed in time, the LBT process can be characterized by the number N corresponding to idle time slots in an extended CCA period rather than a fixed frame period. N can be randomly selected within a certain range. In the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard related to operation in unlicensed spectrum, there are two types of CCA periods for both uplink and downlink transmissions. In the first category, a node can sense the channel for a duration of N time slots, where N can be a random value selected from a range of allowed values ​​called a contention window (CW). The LBT contention window size (CWS) and adjustments can depend on the channel access priority. In the second category, a node can sense the channel in a preconfigured number of time slots.

[0005] For communications between a WTRU and a network node, interference may occur when other nodes (e.g., WiFi transmitters) also communicate with the network node using unlicensed spectrum and when the other nodes are not within the sensing range of the WTRU when the WTRU is close to the network node. This interference (commonly referred to as the "hidden node problem") can be resilient to the LBT process because one WTRU may not be able to sense the transmission of another WTRU. To mitigate the hidden node problem, the contention window may be adjusted before each transmission, taking into account the status of the last transmission. For example, the status of the last transmission may be indicated to the network via an acknowledgement (ACK) or negative acknowledgement (NACK) received for a downlink transmission, or a new data indicator (NDI) may be switched in the case of an uplink transmission. An ACK or NACK may be generally referred to as HARQ-ACK feedback. In an example implementation of the LBT process for downlink transmissions, the CWS may be increased if at least 80% of the HARQ-ACK values ​​for PDSCH transmissions in a reference subframe are NACKs; otherwise it remains unchanged. For uplink transmissions, the WTRU may increase the CWS based on whether the NDI is switched for a reference HARQ ID. The reference HARQ ID may correspond to a grant sent in a reference subframe. Summary of the invention

[0006] Methods and apparatus for communicating on an unlicensed band are provided herein. A method may include sending a transport block in each of a plurality of time slots, and determining a hybrid automatic repeat request (HARQ) state of each of the transmitted transport blocks. The method may also include determining a weighting coefficient for each of the determined HARQ states, and calculating a weighted average of the HARQ states of the transmitted transport blocks based on the determined HARQ states and the weighting coefficients. The method may also include adjusting a listen-before-talk (LBT) contention window size based on the calculated weighted average of the HARQ states. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention may be understood in more detail from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0008] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0009] Figure 1B is a diagram showing that according to one embodiment, Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within a communication system is shown;

[0010] Figure 1C is a diagram showing that according to one embodiment, Figure 1A A system diagram of an example radio access network (RAN) and an example core network (CN) used within the communication system shown;

[0011] Figure 1D is a diagram showing that according to one embodiment, Figure 1A A system diagram of another exemplary RAN and another exemplary CN used within the communication system shown;

[0012] Figure 2 depicts the timing of scheduled HARQ feedback associated with corresponding PDSCH transmissions;

[0013] Figure 3 shows scheduling of HARQ-ACK feedback with varying timing that can be implemented in NR;

[0014] Figure 4 An example of a grouping and adjustment procedure performed by a WTRU is shown;

[0015] Figure 5 An example scenario is described in which a WTRU is configured to group HARQ-ACK states corresponding to a series of PUSCH transmissions; and

[0016] Figure 6 is a flow chart describing an example process for a WTRU to adjust a CWS using a threshold. DETAILED DESCRIPTION

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0045] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, performing bearer activation / deactivation processes, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

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

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

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

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

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

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

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

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

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

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

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

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

[0058] Figure 1D 1 is a system diagram showing the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c using NR radio technology over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0059] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may use beamforming processing to transmit and / or receive signals to and / or from the gNBs 180a, 180b, 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit wireless signals to the WTRU 102a, and receive wireless signals from the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

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

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

[0062] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support network slicing, DC, implement interworking between NR and E-UTRA, route user plane data to user plane functions (UPFs) 184a, 184b, and route control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. Figure 1D As shown, gNB180a, 180b, and 180c can communicate with each other through the Xn interface.

[0063] Figure 1DThe CN 106 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and may include a data network (DN) 185a, 185b. Although the foregoing components are described as part of the CN 106, it should be understood that any of these components may be owned and / or operated by an entity other than the CN operator.

[0064] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, terminating non-access stratum (NAS) signaling, and mobility management, etc. The AMF 182a, 182b may use network slicing processing to customize the CN support provided to the WTRU 102a, 102b, 102c based on the type of service used by the WTRU 102a, 102b, 102c. As an example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, and services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that use other radio technologies (e.g., LTE, LTE-A, LTE-A Pro, and / or non-3rd Generation Partnership Project (3GPP) access technologies such as WiFi).

[0065] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and may configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0066] The UPF 184a, 184b can be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which can provide the WTRUs 102a, 102b, 102c with access to packet-switched networks (e.g., the Internet 110) to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b can perform other functions such as routing and forwarding packets, implementing user plane policies, supporting multi-host PDU sessions, processing user plane QoS, buffering DL packets, and providing mobility anchor processing, etc.

[0067] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the local DNs 185a, 185b and through the UPFs 184a, 184b.

[0068] In view of Figures 1A-1D and about Figures 1A-1D , one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a-d, base station 114a-b, eNodeB 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or one or more other devices described herein. These simulation devices may be one or more devices configured to simulate one or more or all of the functions described herein. For example, these simulation devices may be used to test other devices and / or simulate network and / or WTRU functions.

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

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

[0071] 3GPP has released standards for New Radio (NR) technology. Unlike LTE, NR may support variable transmission duration / starting symbol and variable HARQ feedback timing. In a variable transmission duration, a physical downlink shared channel (PDSCH) or physical uplink shared channel (PUSCH) transmission may occupy a continuous set of symbols within a time slot. When variable feedback timing is implemented, the downlink control information (DCI) containing the DL assignment may include an indication of the HARQ feedback timing for the WTRU. For example, the indication may identify a semi-statically configured time period during which the HARQ feedback is sent. In addition, NR may support the use of a dynamic HARQ-ACK codebook, for which the size of the codebook depends on the number of scheduled transport blocks (TBs). The next generation Node B (gNB) may use a counter downlink assignment index (DAI) and / or a total DAI in the DCI to indicate the number of previously scheduled TBs. In one embodiment, the counter DAI and the total DAI indicator may each or together have a size of two bits, which may allow the WTRU to recover up to four missing TBs. In other embodiments, the counter DAI and the total DAI indicator may each or together have more or fewer bits and may allow the WTRU to recover more or fewer bits.

[0072] 3GPP has started a work item to support NR operation in unlicensed bands. One purpose of this work item may be to specify NR-based operations in unlicensed spectrum (including initial access, scheduling / HARQ, and mobility), as well as coexistence methods for operating with LTE-LAA and other incumbent radio access technologies (RATs). Deployment scenarios may include different independent NR-based operations. For example, variants of dual-connectivity operations may be implemented, such as E-UTRAN New Radio Dual Connectivity (EN-DC) with at least one carrier operating according to the LTE RAT or NR DC with at least two sets of one or more carriers operating according to the NR RAT. Variants of carrier aggregation (CA) may also be implemented, which may include different combinations of zero or more carriers for each of LTE and NRRAT.

[0073] At the study item stage, it was agreed to support four categories of channel access schemes, for example for NR-U operation. Category 1 channel access may involve transmission immediately after a short switching gap. Category 2 channel access may involve LBT operation without random backoff, while categories 3 and 4 may include LBT operation with random backoff and fixed contention window size (CWS) and listen-before-talk (LBT) operation with random backoff and variable contention window size, respectively.

[0074] NR-U may also support the possibility to temporarily disable the transmission of HARQ-ACK feedback for a given PDSCH transmission, and the possibility to later request HARQ-ACK feedback using DCI without scheduling a transport block (TB).

[0075] In LTE-based operation within unlicensed spectrum, an evolved Node B (eNB) may rely on the indicated state of one or more PDSCH transmissions in order to adjust the CW. Prior to transmission on the PDSCH, the eNB may maintain a CWS associated with a channel access priority level p. The CWS may be increased or decreased by determining a HARQ-ACK value corresponding to one or more PDSCH transmissions in a reference subframe. The reference subframe may be the starting subframe of the most recent transmission performed by the eNB on the carrier, and for which the HARQ-ACK is expected to be available. In LTE, the HARQ-ACK feedback is sent on the licensed spectrum and it is not subject to CCA success or failure. For uplink transmissions, the WTRU may adjust the CWS based on the new data indicator (NDI) of the most recent uplink transmission. One problem caused by the additional process in NR is that the HARQ-ACK feedback in NR-U may be sent on the unlicensed spectrum. Therefore, the availability of the HARQ-ACK state of the last transmission (one or more) at the gNB may not be guaranteed.

[0076] Figure 2 The timing of scheduled HARQ feedback associated with the corresponding PDSCH transmission is shown. As shown, the gNB may send a transport block via PDSCH 210 in time slot n-4 and schedule the WTRU's HARQ-ACK feedback transmission in time slot n. Due to the LBT failure, the HARQ-ACK state of the PDSCH may not be available as expected in time slot n-4. At the gNB, it may not be clear whether the WTRU did not receive the PDSCH transmission or whether the HARQ-ACK transmission failed due to the WTRU's LBT mechanism. For example, it may not be obvious whether a hidden node problem or collision occurred during the transmission on the PDSCH. In another example, the PUCCH resources indicated by the PDSCH-to-HARQ (PDSCH-to-HARQ) parameters may fall outside the channel occupied time (COT). In the latter case, similar to the LBT failure, the HARQ-ACK state of the corresponding PDSCH will not be available at least until a new COT is established.

[0077] Another issue may be that supporting flexible HARQ timing (e.g., dynamic indication of PDSCH-to-HARQ) may result in multiple PDSCH transmissions occurring in the same time slot, and may result in HARQ-ACK feedback being signaled in different time slots. Different HARQ-ACK feedback arriving in different time slots may experience different channel conditions.

[0078] Figure 3 The scheduling of HARQ-ACK feedback with varying timing that can be implemented in NR is shown. For example, for three separate PDSCH transmissions 310, 320, and 330 sent in time slot n-4, as shown, the HARQ-ACK feedback for each arrives in time slots n-3, n-2, and n-1, respectively. The transmissions for the three HARQ feedback may experience different channel conditions and may experience LBT failure or success. In addition, as Figure 3 As shown, the duration of a PDSCH transmission in time slot n-4 may vary. A short transmission may experience different channel conditions than a long transmission. Also as shown, the start time and / or end time of a PDSCH transmission in a given time slot may also vary.

[0079] Methods and apparatus for adjusting CWS are described herein. These solutions may take into account, for example, uncertainty in the HARQ-ACK state of previous transmissions at the transmitter side and variable duration and timing of transmissions. As used herein, the term "transmitting node" may refer to a WTRU, a gNB, or any transmitter for wireless communication. Such an apparatus may be configured to operate, for example, in the NR unlicensed spectrum.

[0080] Embodiments related to CW adjustment are disclosed herein. In one set of solutions, a transmitting node may be configured with a set of values ​​from which the CW may be changed. For example, a transmitting node may be configured with a set of values ​​S = {W 1 ,W 2 ,…,W N The contention window adjustment process may include increasing the window size by one or more steps (e.g., from W 1 To W 2 Or from W 1 To W k , such that k <= N), reduce the size by one or more steps (e.g., from W 2 To W 1 Or from W k To W 1 , such that k<=N) and / or reset the window size to a default value. In an example solution, the default value may be the minimum value of the set, or alternatively, the default value may be preconfigured or fixed in the specification or dynamically determined. The transmitting node may determine the adjustment step size and / or the initial value of the contention window based on one factor or a combination of factors as described below. For example, the transmitting node may determine the initial value and / or the adjustment step size based on the COT duration initiated by another transmitting node. The WTRU may determine the initial value of the CWS based on the COT duration initiated by the gNB.

[0081] In some embodiments, the adjustment step size and / or initial value of the CW may depend on the channel access priority. For example, the WTRU may determine the step size and initial value based on the channel access priority signaled from the network.

[0082] In some embodiments, the adjustment step size and / or initial value of the contention window may depend on the signal and / or channel to be transmitted. For example, if the WTRU is transmitting a scheduling request or HARQ-ACK feedback, the WTRU may select the minimum value from a set of allowed values.

[0083] In some embodiments, the adjustment step and / or initial value of the contention window may depend on the number of contention window adjustments previously performed by the transmitting node.

[0084] In some solutions, the transmitting node may be configured to adjust the contention window corresponding to a given channel access priority (CAP) based only on one or more previous transmissions with the channel access priority. For example, the transmitting node may be configured to perform multiple channel accesses with different priority levels. The transmitting node may adjust the CWS by determining the status of previous transmissions performed using the channel access priority level.

[0085] In other solutions, the transmitting node may be configured to adjust the CWS corresponding to a given channel access priority based on one or more previous transmissions having a channel access priority within a category subset for the same channel access category. For example, the transmitting node may be configured to use a channel access category with four different priority levels p1, p2, p3, and p4. The transmitting node may adjust the CWS of a CAP based on the mapping of channel access priorities shown in Table 1, which describes an example mapping between transmissions of a single CAP and other CAPs. CAP Mapped CAP subsets considered in CWS adjustment p1 p1 p2 p1,p2 p3 p1,p2,p3 p4 p1,p2,p3,p4 Table 1: Mapping between individual CAPs and CAP subsets

[0086] In this example, to adjust the CW size for a transmission with channel access priority p1, the node may only consider the state of the previous one or more transmissions with channel access priority p1. For priority p4, the node may consider all transmissions with different channel access priorities p1, p2, p3, and p4 in order to adjust the contention window. This mapping may be semi-statically configured using higher layer signaling or dynamically indicated by the receiving node using, for example, DCI (in the case where the transmitting node is a WTRU and the receiving node is a gNB) or sequence-based signaling.

[0087] In other solutions, the transmitting node can group the transmission status based on the service type of the transmission and adjust the CWS for each service type. For example, when performing CW adjustment to send URLLC packets, the transmitting node can only consider the HARQ-ACK status of URLLC-type services.

[0088] In some solutions, the transmitting node may be configured to adjust the CW for a given channel access category based only on one or more previous transmissions performed using the channel access category. For example, the transmitting node may be configured to use a single multi-channel access category. The transmitting node may adjust the CW by determining the state of previous transmissions performed using the channel access category. In another solution, the transmitting node may be configured to adjust the CW for a given channel access category based on one or more previous transmissions performed using a subset of channel access categories. The transmitting node may be configured with a mapping between a single channel access category and a set of channel access categories to be considered, wherein the mapping is semi-statically configured using, for example, RRC signaling, or dynamically configured using, for example, DCI or sequence-based signals.

[0089] In some solutions, the transmitting node may adjust the CWS based on one or a combination of parameters. For example, one parameter for adjusting the CWS may be the HARQ-ACK state of one or more PDSCH or PUSCH transmissions received in a reference subframe or a set of reference subframes. Another parameter may be the HARQ-ACK state of a PDSCH or PUSCH transmission performed in a reference subframe.

[0090] The transmitting node may adjust the CWS based on one or more measurement reports or measurement results. The measurement reports or results may include a channel quality indicator (CQI) range; channel state information (CSI); SRS transmission; SINR estimation over a set of time slots prior to one or more transmissions; energy sensed over a set of time slots prior to the one or more transmissions; radio link quality measurement (e.g., radio link monitoring (RLM)); received power measurement for layer 1 reference signal received power (L1-RSRP); received CSI reference signal power (CSI-RSRP); received CSI reference signal quality (CSI-RSRQ); beam correlation measurement; digital configuration (e.g., subcarrier spacing); received signal strength indicator (RSSI); or channel occupancy (CO). For example, the CO for each LBT subband may be determined based on the channel load.

[0091] The transmitting node may adjust the CW based on the number N of time slot durations sensed during a previous CW adjustment. The adjustment may be made based on the number of time slots in which the channel is determined to be idle, such as those time slots in which the detected energy is below a certain threshold. The adjustment may also be made based on the number of time slots in which the channel is determined to be busy, such as those time slots in which the detected energy is above a certain threshold. The adjustment may be based on the number of idle and idle time slots and / or the sum of the number of times the LBT process is postponed. The adjustment may also be based on the total time of one or more previous LBT processes, and / or based on the average amount of time for a set of previous LBT processes.

[0092] In some solutions, the transmitting node may be configured to perform a CW adjustment process on each subband within an active bandwidth part (BWP). For example, the transmitting node may operate on a wide bandwidth part (WBWP) having multiple subbands and perform an LBT process on a per-subband basis. The node may perform a channel access process at a frequency size equal to 20 MHz. For example, if the transmission fails in the first subband, the second subband CW may not be increased. In a first set of solutions, the transmitting node may adjust the CW process independently of other CW adjustment processes. In another set of solutions, the transmitting node may adjust the CW process considering one or more states of other CWS processes. For example, if the frequency offset between two subbands is less than a threshold, the transmitting node may consider the CW process state of an adjacent subband.

[0093] In some solutions, assuming that multiple BWPs are configured within a carrier, the transmitting node can be configured to maintain a CW adjustment process for each BWP. In this case, the transmitting node can adjust one CW adjustment process independently of other CW adjustment processes corresponding to different BWPs.

[0094] In some solutions, a transmitting node may acquire a set of LBT subbands for transmission, which may be located within a BWP. The transmitting node may use broadband LBT covering all LBT subbands, and may use a CWS process applicable to all LBT subbands. In another approach, a broadband CWS value may be determined based on all CWS values ​​for each independent LBT subband. In another approach, a transmitting node may perform multiple LBT processes (e.g., one process for each LBT subband) and may use an independent CW adjustment process for each independent LBT subband. In yet another approach, a transmitting node may perform multiple LBT processes, and may use a single CWS value, which may be determined as a function of all CWS values ​​for each independent LBT subband.

[0095] When the WTRU uses a CWS value that is a function of a set of CWS values ​​determined based on a set of LBT subbands, the function may consist of at least one of several elements. For example, the CWS value used may be the maximum or minimum CWS value among all LBT subbands considered. The CWS value used may be an average CWS value determined based on the CWS values ​​of all LBT subbands considered. The CWS value used may be the CWS value of the LBT subband with the highest or lowest index. The CWS value used may be the CWS value of the LBT subband, which may be network configurable or indicated by the network. The CWS value used may be a CWS value that is configurable for the set of LBT subbands or indicated by the network. The CWS value used may be the most recently used CWS for any LBT subband within the BWP, or the CWS value used may be an adjustment (e.g., an incremental increase or decrease relative to a previously used value).

[0096] The CWS for a set of LBT subbands may be stored in one or all CWS processes corresponding to each LBT subband, or retained for use with one or all CWS processes corresponding to each LBT subband. Any such stored one or more CWSs may be used in subsequent LBT processes. In another approach, the CWS for a set of LBT subbands may be stored in a CWS process for any future use of that particular set of LBT subbands.

[0097] In some solutions, the transmitting node may adjust the CWS based on auxiliary information received from the receiving node. For example, the WTRU may adjust its CWS based on information received from the gNB. Such information may be explicitly signaled, for example, via a field in the DCI, or implicitly derived from other received signals such as RRC configured parameters. For example, in the case where the gNB sends a sequence-based signal to indicate the start of a shared COT, the sequence used by the gNB may indicate the CWS and / or the initial value to be used by the WTRU when adjusting the CWS. In another example, the sequence used may indicate whether a CWS adjustment is required.

[0098] In yet another embodiment, the WTRU may use information such as a PDCCH monitoring opportunity set, a control resource set (CORESET), or a search space attribute to determine information for the CWS adjustment.

[0099] In some solutions, the transmitting node and the receiving node may coordinate to maintain the same CW. Such coordination may be supported by exchanging CWS information explicitly or implicitly. For example, the WTRU may receive the CWS to be used for uplink transmission within the scheduling DCI. In another example, the WTRU may implicitly determine the CWS used by the receiving node.

[0100] In some solutions, the transmitting node may need to consider the digital configuration, such as subcarrier spacing, slot duration, CP length, etc., to adjust the CW. In one example, the WTRU may detect the DCI of a switched DL BWP. If the active DL BWP and the initial DL BWP have different subcarrier spacing (SCS) and different CP length, the WTRU may need to consider the digital configuration of the initial BWP for CW adjustment on the active BWP. In one example, if the previous CW size adjustment was based on sensing N slot durations with 15KHz subcarrier spacing in the initial BWP, assuming that the slot duration in the active BWP is half of the initial BWP, the WTRU may need to consider sensing 2N slot durations with 30KHz subcarrier spacing in the active BWP.

[0101] The solutions proposed in the above sections can be applied alone or in combination with the proposed contention window adjustment solution to subsequent uplink and downlink transmissions.

[0102] Embodiments of contention window adjustment for uplink transmissions are described herein. An uplink transmission may include any transmission generated by the WTRU. By way of example and not limitation, it may include transmissions using PUCCH, PUSCH, PRACH, or SRS. The solutions presented below may be applied alone or in combination. For uplink transmissions, the WTRU may be configured to determine the HARQ-ACK status of one or more previous transmissions based on explicit HARQ-ACK feedback from the gNB or based on NDI switching of those HARQ IDs used in uplink grants of subsequent transmissions.

[0103] In a first set of solutions, the WTRU may be configured to consider the HARQ-ACK status of PUSCH transmissions within a configured time window or within a set of time slots before the CW adjustment process. The time window size may be associated with a particular channel access category or channel access priority. The WTRU may be configured to group the HARQ-ACK states corresponding to multiple transmissions, average the HARQ-ACK values ​​within the group, and determine a weighted average over the group. The WTRU may apply a weighting factor to each HARQ-ACK value for each time slot or set of time slots. The WTRU may be configured to group the HARQ-ACK states of uplink transmissions, or may do so autonomously based on one or more of several factors as described herein.

[0104] Figure 4An example of a grouping and adjustment process performed by a WTRU is shown. As shown, the WTRU may determine to group the HARQ-ACK states based on the duration of one or more PUSCH transmissions and / or the position of the PUSCH transmissions within a window before the CW adjustment process. Figure 4 As shown, the WTRU may be configured to transmit a series of transmissions over the PUSCH in a set of reference time slots n to n+4. A first transmission 410 may be transmitted by the WTRU in time slot n, a second transmission 420 may be transmitted by the WTRU in time slot n+2, and a third transmission 430 may be transmitted by the WTRU in time slot n+4. The PUSCH transmissions 410, 420, and 430 may have different durations and / or different start times, as shown. HARQ-ACK states may be received at the WTRU from a network node, as shown at 440, 450, and 460. The WTRU may group this information and average the values ​​of the HARQ-ACK states corresponding to the HARQ-ACK feedback 440, 450, and 460 for the PUSCH transmissions 410, 420, and 430. In some embodiments, the WTRU may apply a weighting factor to any or all of the determined HARQ-ACK states, Figure 4 Shown as C1, C2 and C3.

[0105] Described herein are several factors based on which the WTRU may determine to group the HARQ-ACK states. In some embodiments, for example, the WTRU may determine to group the HARQ-ACK states based on whether a grant-based PUSCH transmission occurred or whether a configured grant was transmitted.

[0106] In some embodiments, the WTRU may determine to group the HARQ-ACK states based on a channel access category or priority, or the WTRU may determine to group the HARQ-ACK states based on a priority or LBT category used by the gNB to schedule the grant. The WTRU may determine to group the HARQ-ACK states based on the CORESET or search space on which the DCI scheduling the one or more transmissions is received. The WTRU may determine to group the HARQ-ACK states based on the monitoring periodicity of the search space on which the DCI scheduling the transmission is received. In some embodiments, the WTRU may determine to group the HARQ-ACK states based on the transmission configuration indicator (TCI) state on which the DCI scheduling the transmission is received. The WTRU may determine to group the HARQ-ACK states based on the bandwidth part on which the DCI scheduling the transmission is received.

[0107] The WTRU may determine to group the HARQ-ACK states transmitted by the gNB based on some a priori knowledge, such as knowledge about discontinuous transmission (DTX) at the gNB due to failure of the LBT process at the WTRU, DTX at the gNB due to misdetection of PUSCH, PUSCH transmission attributes such as MCS, redundancy version (RV) or repetition number, or HARQ process information such as HARQ ID.

[0108] In some solutions, the WTRU may receive configuration information from the network with weighted average coefficients for each group. For example, the WTRU may receive an RRC configuration that associates coefficients with each group. In another solution, the DCI that schedules the transmission may indicate the coefficients for the group transmission. In another solution, the WTRU may autonomously determine the coefficients for the weighted average, for example based on the type of traffic scheduled in the group. The WTRU may apply the weighted coefficients on a set of HARQ-ACK values, or, as described above, the WTRU may apply the weighted coefficients to each HARQ-ACK value for each time slot or set of time slots.

[0109] Figure 5 An example scenario is described in which a WTRU is configured to group HARQ-ACK states corresponding to a series of PUSCH transmissions. As shown, the WTRU may transmit a series of transmissions on the PUSCH in a set of reference time slots n to n+6. A first transmission 510 may be transmitted by the WTRU in time slot n, a second transmission 520 may be transmitted by the WTRU in time slot n+2, a third transmission 530 may be transmitted by the WTRU in time slot n+4, and a fourth transmission 540 may be transmitted by the WTRU in time slot n+6. The PUSCH transmissions 510, 520, 530, and 540 may have different durations and / or different start times. In subsequent time slots, the WTRU may receive HARQ feedback or determine the HARQ-ACK states 551, 552, 561, and 562 corresponding to each of the PUSCH transmissions 510, 520, 530, and 540. The HARQ-ACK states 551, 552, 561, and 562 may include a single bit value of 0 or 1 and may be received by the WTRU from a network node. Alternatively, the HARQ-ACK state may be implicitly determined based on a toggle of the NDI field in the DCI. For example, the WTRU may group the HARQ-ACK feedback into groups 550 and 560 based on one or more factors described in the above paragraphs, and the WTRU may average the values ​​of the HARQ-ACK states for each group. In the illustrated embodiment, the WTRU may also apply a weighting factor to each of the HARQ-ACK state groups shown by C1 and C2.

[0110] In some solutions, the WTRU may be configured to adjust the CWS considering the per-CBG HARQ-ACK state. In the first set of solutions, the WTRU may be configured to consider the per-TB HARQ-ACK state and the per-CBG HARQ-ACK state differently. For example, the WTRU may perform a weighted average between all HARQ-ACK states, with a lower weight assigned to the per-CBG HARQ-ACK state. In other solutions, the WTRU may be configured to assign the same weight to the per-TB and per-CBG HARQ-ACK states, for example if the gNB maps the CBG to the entire subband. Upon receiving an uplink grant and determining that the CBG is mapped to the entire subband, the per-CBG HARQ-ACK state may give the WTRU the channel conditions for the entire subband. The WTRU may be configured to determine the HARQ-ACK state of the CBG using the CBG transmission indication and / or CBG flush indication received in the DCI scheduling the UL grant.

[0111] In some solutions, the WTRU may adjust the contention window size based on a channel quality indicator (CQI) determination in a reference time slot, in a set of time slots, or in a configured time window before performing the CW adjustment procedure. For example, the WTRU may be configured to calculate an average of the CQIs determined over K time slots before the CW adjustment. In some embodiments, the WTRU may be configured to calculate a weighted average of the CQIs. For example, the WTRU may be configured to apply a higher coefficient to the most recently determined CQI compared to an earlier CQI. In addition, the WTRU may be configured with a set of CQI average thresholds, and each threshold may correspond to one or more step sizes of the contention window adjustment procedure. For example, the WTRU may be configured with {T 1 ,T 2 ,…,T N} threshold. If the calculated average value is within T i and T i+1 If the calculated average value is between T i+1 and T i+2 If the value is between , CWS can increase by two steps.

[0112] In one solution, the WTRU may be configured with a CWS based on a measurement received in a configured reference signal or another signal. The measurement may be in the form of path loss, estimated SINR, or another metric related to signal quality or signal strength.

[0113] The WTRU may be configured with one or more thresholds and one or more CWS values ​​by which the applicable CWS is determined. This determination may be made based on WTRU measurements or may be directed by the gNB.

[0114] Figure 6 is a flow chart depicting an exemplary process for a WTRU to adjust the CWS using a threshold. As shown, at 610, the WTRU may be configured with an initial CW size and one or more thresholds. The initial CW size and / or threshold may be configured by semi-static signaling or dynamically determined. At 620, the WTRU may calculate an average or weighted average of multiple HARQ states, for example according to the above method. In the event that the average or weighted average of the HARQ states is less than the threshold, the WTRU may determine to maintain the CW at the initial CWS. In the event that the calculated average is equal to or exceeds the threshold, the WTRU may determine to increase the CWS by applying a CWS adjustment step size, as shown in 630. For example, as generally described in the above paragraphs regarding CW adjustment, the WTRU may be configured to have a set of adjustment step sizes S = {W 1 ,W 2 ,…,W N In some embodiments, for example, the WTRU may apply successive adjustment steps W based on the number of previously performed adjustments. 1 or W 2 In another embodiment, the WTRU may apply successive adjustment steps depending on whether the calculated average or weighted average exceeds a further threshold in addition to the first threshold.

[0115] In one solution, the WTRU may be configured to determine the CWS based on downlink measurements such as path loss calculations, RSSI, radio resource management (RRM) parameters, or CO values, any of which may be used to estimate the uplink SINR. In some embodiments, the WTRU may be configured with two thresholds T 1 and T 2 , and three CWS values. Thus, based on the CQI estimation, the WTRU may select one of the three pre-configured CWS values ​​by comparing the estimated CQI with the configured threshold.

[0116] In an alternative solution, the WTRU may be configured to determine the CWS based on another configured parameter, such as the MCS used for a scheduled uplink transmission. In one case, the WTRU may be configured to have, for example, two thresholds T 1 and T 2, and three CWS values. Based on the MCS configured for the most recent or immediately scheduled uplink transmission, the WTRU may select one of the three pre-configured CWS values, for example, by comparing the configured MCS with a configured threshold.

[0117] In some solutions, the WTRU may adjust the contention window size based on the COT characteristics of the gNB. For example, based on the COT duration of the gNB, the WTRU may adjust the CWS accordingly. If the COT duration of the gNB is relatively long (e.g., 10ms), in order to ensure fairness between nodes using other RATs such as wireless local area network (WLAN), the WTRU may be configured to increase the CWS during the access channel procedure.

[0118] Embodiments of CW adjustment for downlink transmissions are described herein. One or more downlink transmissions may include any transmission generated by the gNB. By way of example and not limitation, downlink transmissions may include transmissions using PDCCH, PDSCH, PBCH, PSS / SSS, DMRS, or CSI-RS. The solutions proposed below may be applied individually or in combination.

[0119] In some solutions, the gNB may adjust the contention window size for one or more transmissions based on the HARQ-ACK status of one or more previous transmissions performed in one or more reference time slots. In one set of solutions, the gNB may group the HARQ-ACK feedbacks based on the arrival time of each ACK / NACK feedback. For example, each HARQ-ACK that arrives at the same time or arrives in the same sub-time slot or arrives in the same time slot may be associated with the same group. Such feedback may be considered to share the same HARQ-ACK timing.

[0120] In one example solution, a group of NACKs with the same HARQ-ACK timing may be averaged. A weighted average may then be calculated based on the averages obtained for each HARQ-ACK timing. The weight applied to each HARQ timing group may be semi-statically configured or dynamically adapted based on the WTRU's measurement reports. In one scenario, the gNB may adjust the CWS if the weighted average is above a configured threshold.

[0121] Alternatively, the gNB may be configured with a set of weighted average thresholds, each corresponding to a CW adjustment step size. In the corresponding scenario, the gNB may attempt to access the channel in slot n, and the reference slot may have relative timing n-3. The gNB may have performed M in slot n-3. 1PDSCH transmission for which the gNB expects feedback in slot n-2. The gNB may also have performed M in slot n-3. 2 PDSCH transmission for which the gNB expects feedback in slot n-1. Finally, the gNB may have performed M 3 PDSCH transmissions for which the gNB expects feedback in slot n. In this example, the weighted average may be calculated as follows: For each group M i , And the weighted average can be equal to Where 0≤c i ≤1.

[0122] In another solution, the gNB may group the HARQ-ACK feedback based on the duration of one or more PDSCH transmissions and / or based on the position of the PDSCH transmission within a slot. The values ​​of each HARQ-ACK associated with a certain starting position and / or duration may be averaged. A weighted average may then be calculated over the averages obtained for each HARQ-ACK group. The weights for each HARQ group may be semi-statically configured or dynamically adapted based on any of the above downlink measurements reported by the WTRU.

[0123] In a set of solutions, to adjust the CW, the gNB may consider the status of HARQ-ACK feedback transmitted by WTRUs using a specific channel access category and / or priority. In one example, the gNB may consider the HARQ-ACK status from a WTRU using a channel access category that specifies transmission immediately after a short switching gap. In another example, the gNB may consider the HARQ-ACK status from a WTRU using a channel access category without random backoff. In another example, the gNB may group the HARQ-ACK status based on the channel access category used by the WTRU. A weighted average may be calculated between the groups, with each group having a different weight. For example, a HARQ-ACK status group from a WTRU using a channel access category that transmits immediately after a short switching gap may have a higher weight than HARQ-ACK feedback from a WTRU that performs channel access without random backoff.

[0124] In other solutions, the gNB may consider HARQ-ACK feedback triggered by DCI instead of scheduling. These solutions may be applied, for example, if the gNB schedules transport blocks without providing HARQ-ACK timing and triggers the transmission of, for example, HARQ-ACK feedback corresponding to the scheduled transport blocks in a subsequent time slot. Such HARQ-ACK feedback may have a higher priority or weighting factor when used to calculate the weighted average.

[0125] In some solutions, the gNB may determine that a NACK has been indicated for a given transmission based on one or more conditions. In one example case, the gNB may simply receive a NACK from the WTRU. In another example condition, no HARQ-ACK feedback is received, or DTX is detected in K slots and / or symbols. In another case, no HARQ-ACK feedback is received within the scheduled HARQ-ACK time frame, but one or more uplink transmissions may be received from the WTRU in one or more subsequent slots or symbols. The uplink transmission may include a scheduling request, a PRACH transmission, a configured granted PUSCH transmission, and / or a granted-based PUSCH transmission. In another condition, the number of NACKs received per CBG for a transport block may exceed a threshold.

[0126] In some solutions, the gNB may consider the per-CBG HARQ-ACK state to adjust the contention window size. In the first set of solutions, the gNB may consider the per-TB HARQ-ACK and per-CBG HARQ-ACK states differently. For example, the gNB may perform a weighted average of all ACK / NACK values, with a lower weight assigned to the per-CBG HARQ-ACK feedback. In other sets of solutions, the gNB may assign the same weight to the per-TB and per-CBG HARQ-ACK states. For example, the gNB may map the CBG to the entire subband. In this case, the per-CBG HARQ-ACK state may indicate the channel condition for the entire subband.

[0127] In one solution, the WTRU may be configured with a CWS based on measurements of a configured reference signal or another signal. The measurements may be in the form of SNR, SINR, CO, RSSI, or another metric. In some solutions, before the CWS is adjusted, the gNB may adjust the CWS based on CQI reports received from the WTRU in the reference timeslot or measurements made by the WTRU in the reference timeslot or a set of timeslots. For example, the gNB may calculate the average CQI reported by different WTRUs in the reference timeslot or a set of timeslots.

[0128] The WTRU may be configured with one or more thresholds and one or more CWS values ​​to determine the applicable CWS. This determination may be based on WTRU measurements or may be directed by the gNB.

[0129] In some solutions, the WTRU may be configured to determine the CWS based on downlink measurements (e.g., CSI-RS or DMRS), and estimate the downlink CQI or SINR. In one case, the WTRU may be configured with two thresholds T 1 and T 2 , and three CWS values. Thus, based on its CQI estimate, the WTRU may select one of the three pre-configured CWS values ​​by comparing the estimated CQI with the configured threshold.

[0130] In an alternative solution, the WTRU may be configured to determine the CWS based on another configuration parameter, such as the MCS used for the scheduled transmission. In an exemplary case, the WTRU may be configured with two thresholds T 1 and T 2 , and three CWS values. Based on its configured MCS for the most recent or immediately scheduled transmission, the WTRU may select one of the three pre-configured CWS values ​​by comparing the configured MCS to the configured thresholds. In other cases, a greater or lesser number of thresholds and / or a greater or lesser number of CWS values ​​may be implemented.

[0131] The WTRU may be configured to report the presence of hidden nodes. The WTRU may determine the presence of hidden nodes based on interference measurements. In another approach, the WTRU may determine the presence of hidden nodes based on past attempts by the WTRU to perform an LBT procedure. For example, the WTRU may perform an LBT procedure at a configurable time instance and determine whether the channel is idle from its perspective. The WTRU may then report these results, possibly in a future transmission.

[0132] Although the features and elements are described above in specific combinations, one of ordinary skill in the art will recognize that each feature or element can be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware that is incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, buffer memory, semiconductor storage devices, magnetic media (e.g., internal hard disks and removable disks), magneto-optical media, and optical media (e.g., CD-ROM discs and digital versatile discs (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC, or any computer host.

Claims

1. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: sending one or more physical uplink shared channel (PUSCH) transmissions comprising a plurality of transport blocks (TBs); receiving a first hybrid automatic repeat request (HARQ) feedback for a plurality of code block groups (CBGs) included in a first TB of the plurality of TBs, wherein the first HARQ feedback corresponds to a CBG-based HARQ feedback, and for each of the plurality of CBGs included in the first TB, a corresponding HARQ acknowledgement / negative acknowledgement (ACK / NACK) is received; adjusting a contention window size (CWS) based on the first HARQ feedback corresponding to the plurality of CBGs, wherein the CWS is adjusted according to a first rule based on the first received HARQ feedback corresponding to the CBG-based HARQ feedback; receiving a second HARQ feedback for a second TB of the plurality of TBs, wherein the second HARQ feedback corresponds to the TB-based HARQ feedback and a single HARQ ACK / NACK is received for the second TB; adjusting the CWS based on the second HARQ feedback corresponding to the TB, wherein the CWS is adjusted according to a second rule based on the second HARQ feedback corresponding to the HARQ feedback based on the TB, wherein the WTRU applies a greater weight to the single HARQ ACK / NACK received for the second TB when applying the second rule than to each corresponding HARQ ACK / NACK for each of the plurality of CBGs when applying the first rule; determining, based on the adjusted CWS, that a channel for sending at least a second PUSCH transmission is idle; and Based on determining that the channel is idle, sending the second PUSCH transmission.

2. The method according to claim 1, wherein: At least one of the received first HARQ feedback or the received second HARQ feedback is received within a time window.

3. The method according to claim 2, wherein: The time window is defined by a set of time slots.

4. The method according to claim 1, wherein: The CWS is adjusted according to the first rule based on: applying a first weighting coefficient to the first received HARQ feedback corresponding to the CBG-based HARQ feedback and comparing the weighted HARQ to a first threshold; as well as The CWS is adjusted according to the second rule based on: applying a second weighting coefficient to the second received HARQ feedback corresponding to the TB-based HARQ feedback, and comparing the weighted second received HARQ feedback with a second threshold. The method of claim 4 , wherein the first weighting coefficient and the second weighting coefficient are different.

6. A wireless transmit / receive unit (WTRU), the WTRU comprising: a transceiver configured to transmit one or more physical uplink shared channel (PUSCH) transmissions comprising a plurality of transport blocks (TBs); The transceiver is further configured to receive a first hybrid automatic repeat request (HARQ) feedback for a plurality of code block groups (CBGs) included in a first TB of the plurality of TBs, wherein the first HARQ feedback corresponds to a CBG-based HARQ feedback, and for each of the plurality of CBGs included in the first TB, a corresponding HARQ acknowledgement / negative acknowledgement (ACK / NACK) is received; a processor configured to adjust a contention window size (CWS) based on the first HARQ feedback corresponding to the plurality of CBGs, wherein the CWS is adjusted according to a first rule based on the first received HARQ feedback corresponding to the CBG-based HARQ feedback; The transceiver is further configured to receive a second HARQ feedback for a second TB of the plurality of TBs, wherein the second HARQ feedback corresponds to TB-based HARQ feedback and a single HARQ ACK / NACK is received for the second TB; The processor is further configured to adjust the CWS based on the second HARQ feedback corresponding to the TB, wherein the CWS is adjusted according to a second rule based on the second HARQ feedback corresponding to the HARQ feedback based on the TB, wherein the WTRU is configured to, when applying the second rule, apply a greater weight to the single HARQ ACK / NACK received for the second TB than a weight applied to each corresponding HARQ ACK / NACK for each of the plurality of CBGs when applying the first rule; The processor is further configured to determine, based on the adjusted CWS, that a channel for sending at least a second PUSCH transmission is idle; and The transceiver is further configured to send the second PUSCH transmission based on determining that the channel is idle.

7. The WTRU of claim 6, wherein at least one of the received first HARQ feedback or the received second HARQ feedback is received within a time window.

8. The WTRU of claim 7, wherein the time window is defined by a set of time slots.

9. The WTRU of claim 6, wherein the processor is further configured to: adjusting the CWS according to the first rule based on applying a first weighting coefficient to the first received HARQ feedback corresponding to the CBG-based HARQ feedback and comparing the weighted first received HARQ feedback to a first threshold; and The CWS is adjusted according to the second rule based on applying a second weighting coefficient to the second received HARQ feedback corresponding to the TB-based HARQ feedback and comparing the weighted second received HARQ feedback to a second threshold.

10. A wireless transmit / receive unit (WTRU), the WTRU comprising a processor and a memory, the processor and the memory configured to: sending at least a first physical uplink shared channel (PUSCH) transmission comprising a transport block (TB); receiving hybrid automatic repeat request (HARQ) feedback for at least a portion of the TB, wherein: The received HARQ feedback corresponds to one of code block group (CBG) based HARQ feedback or TB based HARQ feedback, wherein the CBG based HARQ feedback includes multiple HARQ acknowledgements / negative acknowledgements (ACK / NACK) for multiple CBGs included in the TB, and the TB based HARQ feedback includes a single HARQ ACK / NACK for the TB; resetting a contention window size (CWS) based on the received HARQ feedback, wherein the WTRU is configured to reset the CWS according to a first rule if the received HARQ feedback corresponds to the CBG-based HARQ feedback, and to reset the CWS according to a second rule if the received HARQ feedback corresponds to the TB-based HARQ feedback, wherein the WTRU is configured to, when determining whether to reset the CWS, apply a greater weight to the single HARQ ACK / NACK if the HARQ feedback corresponds to the TB-based HARQ feedback than a weight applied to at least one of the plurality of HARQ ACK / NACKs corresponding to at least one of the plurality of CBGs if the HARQ feedback corresponds to the CBG-based HARQ feedback; Based on the reset CWS, determining that a channel for sending at least a second PUSCH transmission is idle; and Based on determining that the channel is idle, sending the second PUSCH transmission according to the reset CWS.

11. The WTRU of claim 10, wherein the single HARQ ACK / NACK corresponds to an ACK for the TB.

12. The WTRU of claim 10, wherein each corresponding HARQ ACK / NACK for each of the plurality of CBGs corresponds to a corresponding ACK or a corresponding NACK for each of the plurality of CBGs.

13. A wireless transmit / receive unit (WTRU), the WTRU comprising a processor and a memory, the processor and the memory configured to: sending a first physical uplink shared channel (PUSCH) transmission comprising a first transport block (TB); receiving a first hybrid automatic repeat request (HARQ) feedback for the TB, the first HARQ feedback corresponding to the HARQ feedback based on the TB; Determining, based on the first HARQ feedback, to reset a contention window size (CWS) using a first CWS adjustment rule, wherein the first CWS adjustment rule is applied to the HARQ feedback based on the TB; sending a second PUSCH transmission comprising a second transport block, the second TB comprising a plurality of code block groups (CBGs); receiving second HARQ feedback for the plurality of CBGs, the second HARQ feedback corresponding to the CBG-based HARQ feedback; determining, using a second CWS adjustment rule, to reset the CWS based on the second HARQ feedback, wherein the second CWS adjustment rule is applied to CBG-based HARQ feedback, wherein the first CWS adjustment rule applied to TB-based HARQ feedback applies a different criterion than a criterion applied when using the second CWS adjustment rule to determine whether to reset the CWS in response to TB-based HARQ feedback; Based on the reset CWS, determining that a channel for sending at least a third PUSCH transmission is idle; and Based on determining that the channel is idle, sending the third PUSCH transmission according to the reset CWS.

14. The WTRU of claim 13, wherein the first HARQ ACK / NACK corresponds to an ACK for the TB.

15. The WTRU of claim 13, wherein the second HARQ corresponds to a corresponding ACK or a corresponding NACK for each of the plurality of CBGs.

16. A wireless transmit / receive unit (WTRU), the WTRU comprising a processor and a memory, the processor and the memory configured to: receiving hybrid automatic repeat request (HARQ) feedback corresponding to one of transport block (TB) based HARQ feedback or code block group (CBG) based HARQ feedback; and Based on the HARQ feedback, adjusting the contention window size (CWS), wherein: Under the condition that the HARQ feedback corresponds to the TB-based HARQ feedback, the CWS is adjusted according to the first CWS adjustment rule, and under the condition that the HARQ feedback corresponds to the CBG-based HARQ feedback, the CWS is adjusted according to the second CWS adjustment rule.

17. The WTRU of claim 16, wherein the first CWS adjustment rule associated with TB-based HARQ feedback applies different criteria to determine whether to adjust the CWS in response to TB-based HARQ feedback than the criteria applied when using the second CWS adjustment rule associated with CBG-based HARQ feedback.

18. The WTRU of claim 16, wherein the processor and memory are configured to: According to the adjusted CWS, a physical uplink shared channel (PUSCH) transmission is sent.

19. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: receiving hybrid automatic repeat request (HARQ) feedback corresponding to one of transport block (TB) based HARQ feedback or code block group (CBG) based HARQ feedback; and Based on the HARQ feedback, adjust the contention window size (CWS), wherein, under the condition that the HARQ feedback corresponds to the TB-based HARQ feedback, the CWS is adjusted according to a first CWS adjustment rule, and under the condition that the HARQ feedback corresponds to the CBG-based HARQ feedback, the CWS is adjusted according to a second CWS adjustment rule.

20. The method according to claim 19, wherein: The first CWS adjustment rule associated with TB-based HARQ feedback applies different criteria for determining whether to adjust the CWS in response to TB-based HARQ feedback than the criteria applied when using the second CWS adjustment rule associated with CBG-based HARQ feedback.

21. The method of claim 19, wherein the processor and memory are configured to: According to the adjusted CWS, a physical uplink shared channel (PUSCH) transmission is sent.

22. A wireless transmit receive unit (WTRU), the WTRU comprising a processor and a memory, the processor and the memory configured to: determining a set of time slots associated with a time window; determining a weighted average of a channel quality indicator (CQI) over the time window; comparing the weighted average of the CQIs with a threshold to determine an associated contention window size (CWS) adjustment step size; and The CWS is adjusted according to the CWS adjustment determined based on the weighted average of the CQIs.

23. The WTRU of claim 22, wherein the WTRU is configured with a plurality of thresholds, each threshold of the plurality of thresholds being associated with a corresponding CWS adjustment step size.

24. The WTRU of claim 22, wherein the processor and memory are configured to: Based on the path loss measurement, the CWS is adjusted.

25. The WTRU of claim 22, wherein the processor and memory are configured to: The CWS is adjusted based on a modulation and coding scheme associated with the scheduled transmission.

26. A method implemented by a wireless transmit receive unit (WTRU), the method comprising: determining a set of time slots associated with a time window; determining a weighted average of a channel quality indicator (CQI) over the time window; comparing the weighted average of the CQIs with a threshold to determine an associated contention window size (CWS) adjustment step size; and The CWS is adjusted according to the CWS adjustment determined based on the weighted average of the CQIs.

27. The method of claim 26, wherein the WTRU uses a plurality of thresholds, each threshold of the plurality of thresholds being associated with a corresponding CWS adjustment step size.

28. The method of claim 26, further comprising: Based on the path loss measurement, the CWS is adjusted.

29. The method of claim 26, further comprising: The CWS is adjusted based on a modulation and coding scheme associated with the scheduled transmission.

Images