Method and system for sidelink operation for beam-based model 2HARQ in shared spectrum

Abstract

Systems and methods for a sidelink (SL) hybrid automatic repeat request (HARQ) feedback scheme are described. A wireless transmit / receive unit (WTRU) may receive information indicating a plurality of SL transmission configuration indications (TCIs) and information indicating a plurality of hybrid automatic repeat request (HARQ) configurations, wherein the SL TCIs include at least an SL primary TCI (P-TCI) and an SL secondary TCI (S-TCI). The WTRU may determine a channel uncertainty and determine a combination of the set of SL TCIs and a HARQ configuration for communication via a sidelink feedback channel based on a comparison of the channel uncertainty to at least one threshold. The WTRU may transmit a transmission via a sidelink feedback channel using the determined set of SL TCIs and using the determined HARQ configuration.

Description

[0001] Related Applications

[0002] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 413,448, entitled "Methods and Systems of Sidelink Operations for Beam - Based Mode 2 HARQ in Shared Spectrum", filed on October 5, 2022, the entire content of which is incorporated herein by reference. Background Art

[0003] New Radio (NR) Vehicle - to - Everything (V2X) is designed with a broader set of more advanced V2X use cases in mind and is broadly arranged into four use - case groups: platooning, extended sensors, advanced driving, and remote driving.

[0004] Platooning enables vehicles to dynamically form a queue of vehicles traveling together. All vehicles in the queue obtain information from the leading vehicle to manage the queue. This information allows the vehicles to travel closer than normal in a coordinated manner, in the same direction, and together.

[0005] Extended sensors enable the exchange of raw or processed data or live video images collected by local sensors between vehicles, road - side unit, pedestrian devices, and V2X application servers. Vehicles can increase their perception of their environment beyond what their own sensors can detect and have a broader and more comprehensive view of the local situation. High data rate is one of the key features.

[0006] Advanced driving can enable semi - autonomous or fully - autonomous driving. Each vehicle and / or Road - Side Unit (RSU) shares its own perception data obtained from its local sensors with nearby vehicles, and this allows the vehicles to synchronize and coordinate their trajectories or maneuvers. Each vehicle also shares its driving intention with nearby vehicles.

[0007] Remote driving enables a remote driver or V2X application to operate a remote vehicle for passengers who cannot drive themselves or to operate a remote vehicle located in a hazardous environment. For situations with limited variation and predictable routes, such as public transportation, cloud - based driving can be used. High reliability and low latency are the main requirements.

[0008] These and other embodiments may utilize high frequencies (e.g., above 52.6 GHz in some instances). Compared to lower frequency bands, such embodiments face more difficult challenges such as higher phase noise, greater propagation losses due to high atmospheric absorption, lower power amplifier efficiency, and stringent power spectral density regulatory requirements in unlicensed frequency bands. Additionally, the frequency range above 52.6 GHz may contain larger spectral allocations and larger bandwidths that may not be available for frequency bands below 52.6 GHz.

[0009] In some communication systems that use beam-based side links (e.g., for communication between vehicles in V2X applications), due to channel uncertainty, signals may not be correctly transmitted due to listen-before-talk (LBT) failures in some spatial directions. Even if the signal can be transmitted, it may not be received due to interference (e.g., from hidden nodes in the same spatial direction). Some embodiments of hybrid automatic repeat request (HARQ) can help solve this problem, but may cause additional problems: for example, in some instances, HARQ techniques based on negative or negative acknowledgment (NACK) can be utilized, where if a signal is not received, a NACK is sent. However, if the NACK itself is not received, the signal transmitter may incorrectly assume successful transmission. This results in system errors and performance degradation. SUMMARY

[0010] To address the above and other problems, in some aspects, the present disclosure relates to systems and methods for mode 2 operation of side link (SL) beam-based HARQ. A hybrid acknowledgment / negative acknowledgment (ACK / NACK) scheme can be used, where when LBT fails or channel uncertainty (due to noise, interference, low signal level, etc.) is high, ACK is used in addition to (or instead of, depending on the embodiment) NACK, and when LBT fails or channel uncertainty is low, a NACK-only scheme is used for high throughput and low latency. In various embodiments, ACK and / or NACK can be grouped or identify multiple received or lost signals, or individual ACK or NACK can be utilized (i.e., one ACK or NACK per signal or sequence number). In various embodiments, this can similarly be based on channel uncertainty or LBT failure, or any other channel or device condition or characteristic. Thus, a device can dynamically switch between multiple HARQ configurations in response to changing channel conditions (e.g., ACK / NACK feedback scheme, NACK-only feedback scheme, shared ACK / NACK feedback scheme, etc.).

[0011] A method may include receiving configuration information regarding multiple sets of Spatial Relationship (SR) Transmission Configuration Indicator (TCI) and multiple Hybrid Automatic Repeat reQuest (HARQ) feedback schemes. The method may further include determining channel uncertainty based on at least one measurement and at least one threshold. The configuration information may further include multiple HARQ feedback resources. The method may further include receiving an indication of TCI for transmitting a Physical Sidelink Feedback Channel (PSFCH) transmission. The method may further include selecting a TCI type based on the determined channel uncertainty. The method may further include selecting a HARQ feedback scheme based on the determined channel uncertainty. The method may further include selecting a feedback resource based on the determined channel uncertainty. The method may further include transmitting HARQ feedback on the Physical Sidelink Feedback Channel (PSFCH) using the indicated TCI, the selected HARQ feedback scheme, and the selected feedback resource. The multiple sets of TCI may include a Primary TCI (P-TCI) and a Secondary TCI (S-TCI). The multiple HARQ feedback schemes may include an ACK / NACK scheme and a NACK-only scheme. The method may further include using a large TCI set under a condition that the channel uncertainty is greater than a first threshold. The method may further include switching to a separate ACK-NACK HARQ feedback scheme under a condition that the channel uncertainty is greater than a second threshold. The method may further include transmitting a separate ACK or NACK based on a decoding result. The method may further include switching to a NACK-only HARQ feedback scheme under a condition that the channel uncertainty is not greater than the second threshold. The method may further include transmitting a NACK only when decoding fails. The method may further include switching to a NACK-only HARQ feedback scheme under a condition that the channel uncertainty is not greater than the second threshold. The method may further include using a small TCI set under a condition that the channel uncertainty is greater than the first threshold. The method may further include switching to a NACK-only HARQ feedback scheme under a condition that the channel uncertainty is not greater than the first threshold. The method may further include switching to a separate ACK / NACK HARQ feedback scheme under a condition that the channel uncertainty is greater than a third threshold. The large TCI set may include a Primary TCI (P-TCI) and a Secondary TCI (S-TCI). The small TCI set may include a Primary TCI (P-TCI). Additionally, the large TCI set may include only a large set of Primary TCI (P-TCI) or only a large set of Secondary TCI (S-TCI). The small TCI set may include a small set of Secondary TCI (S-TCI). The channel uncertainty may be determined based on at least one of the following: the number of Listen-Before-Talk (LBT) failures, the ratio of LBT failures to total measurements, the ratio of LBT failures to successes, the ratio of NACKs to ACKs, the percentage of NACKs, the Channel Busy Ratio (CBR), and the interference level. Description of the Drawings

[0012] A more detailed understanding can be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals in the drawings indicate like elements, and in which:

[0013] Figure 1A is a system diagram showing an example communication system in which one or more disclosed embodiments can be implemented;

[0014] Figure 1B is a system diagram showing an example wireless transmit / receive unit (WTRU) that can be used within the communication system shown in Figure 1A and is a system diagram showing an example radio access network (RAN) and an example core network (CN) that can be used within the communication system shown in

[0015] Figure 1C is a system diagram showing an example RAN and an example CN that can be used within the communication system shown in Figure 1A and is a system diagram showing another example RAN and another example CN that can be used within the communication system shown in

[0016] Figure 1D is a system diagram showing another example RAN and another example CN that can be used within the communication system shown in Figure 1A and is a system diagram showing an example of 5G V2X and LTE V2V requirements;

[0017] Figure 2 shows an example of 5G V2X and LTE V2V requirements;

[0018] Figure 3 shows an example method of HARQ feedback based on sidelink TCI;

[0019] Figure 4 shows an example method of HARQ feedback based on sidelink TCI;

[0020] Figure 5 is an example method of HARQ feedback based on sidelink TCI with hybrid TCI and HARQ feedback;

[0021] Figure 6 is an example method of HARQ feedback based on sidelink TCI with hybrid TCI and HARQ feedback;

[0022] Figure 7 shows an example method of HARQ feedback based on sidelink TCI with a multi-threshold scheme;

[0023] Figure 8 shows an example method of HARQ feedback based on sidelink TCI with hybrid TCI and HARQ feedback;

[0024] Figure 9 shows an example method of HARQ feedback based on sidelink TCI with hybrid TCI and HARQ feedback;

[0025] Figure 10 Shows an example method of sidelink TCI-based HARQ feedback with a multi-threshold scheme;

[0026] Figure 11 Shows an example method of sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback;

[0027] Figure 12 Shows an example method of sidelink TCI-based HARQ feedback with a multi-threshold scheme;

[0028] Figure 13 Shows an example method using a hybrid scheme of TCI, HARQ feedback, and resource allocation;

[0029] Figure 14 Shows an example method of sidelink TCI-based HARQ feedback with a multi-threshold scheme;

[0030] Figure 15 Shows an example method of sidelink UE-assisted TCI and HARQ feedback;

[0031] Figure 16 Shows an example method of sidelink UE-controlled TCI and HARQ feedback;

[0032] Figure 17 Shows an example method of sidelink UE-controlled TCI and HARQ feedback;

[0033] Figure 18 Shows an example method of TCI indication and feedback scheme indication; and

[0034] Figure 19 Shows an example method of TCI indication and feedback scheme indication with an SL-configurable control container. Detailed implementation mode

[0035] Figure 1AFIG. is a diagram illustrating an exemplary communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multi-access system that provides content such as voice, data, video, messaging, broadcast, etc. to a plurality of wireless users. The communication system 100 may enable the plurality of 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.

[0036] As Figure 1A 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, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any one of which may be referred to as a station (STA)) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular telephones, personal digital assistants (PDA), smart phones, laptop computers, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMD), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automation processing chain), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. Any one of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0037] The communication system 100 may further include base station 114a and / or base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to facilitate its access to one or more communication networks (e.g., CN 106, Internet 110, and / or other networks 112). As an example, base stations 114a, 114b may be base transceiver stations (BTSs), NodeBs, eNodeBs (eNBs), home NodeBs, home eNode Bs, next generation NodeBs (e.g., gNodeBs (gNBs)), new radio (NR) NodeBs, site controllers, access points (APs), wireless routers, etc. Although each of base stations 114a, 114b is described as a single element, it should be understood that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0038] Base station 114a may be part of RAN 104, which may further include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services to a particular geographical area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver corresponding to each sector of the cell. In an embodiment, base station 114a may use multiple-input multiple-output (MIMO) technology and may use multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0039] Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d via 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.). Any suitable radio access technology (RAT) may be used to establish air interface 116.

[0040] More specifically, as described above, the communication system 100 can be a multi-access system and can use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed Uplink (UL) Packet Access (HSUPA).

[0041] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can use Long-Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTA Pro (LTE-A Pro) to establish the air interface 116.

[0042] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can use NR to establish the air interface 116.

[0043] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c can together implement LTE radio access and NR radio access, for example, using the Dual Connectivity (DC) principle. Thus, the air interface used by the WTRUs 102a, 102b, 102c can be characterized by multiple types of radio access technologies and / or transmissions to / from multiple types of base stations (e.g., eNB and gNB).

[0044] 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 (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), GSM Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0045] For example, Figure 1A the base station 114b in [example] may be a wireless router, a home Node B, a home eNode B, or an access point, and may use any suitable RAT to facilitate wireless connections in a local area, such as business premises, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for drones), and roads, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a Wireless Local Area Network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a Wireless Personal Area Network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell or a femto cell. As Figure 1A shown, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106.

[0046] The RAN 104 may communicate 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 varying 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, accounting services, location-based services for mobile devices, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although in Figure 1AThis is not shown in the figure, but it should be understood that the RAN 104 and / or the CN 106 can communicate directly or indirectly with other RANs that use the same RAT or different RATs as the RAN 104. For example, in addition to being connected to the RAN 104 that can use the NR radio technology, the CN 106 can also communicate with another RAN (not shown) that uses GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0047] The CN 106 can also be used 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 can include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 can include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol family. The network 112 can include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 can include another CN connected to one or more RANs, and the one or more RANs can use the same RAT or different RATs as the RAN 104.

[0048] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 can include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks via different wireless links). For example, Figure 1A the illustrated WTRU 102c can be configured to communicate with a base station 114a that can employ a cellular-based radio technology, and with a base station 114b that can employ IEEE 802 radio technology.

[0049] Figure 1B is a system diagram showing an exemplary WTRU 102. As Figure 1B shown, the WTRU 102 can include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It should be understood that the WTRU 102 can include any sub-combination of the foregoing elements while remaining consistent with the embodiments.

[0050] The processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120, and the transceiver 120 can be coupled to the transmit / receive element 122. Although Figure 1B the processor 118 and the transceiver 120 are depicted as separate components, it should be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0051] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (such as base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 can be a transmitter / detector configured to transmit and / or receive signals such as IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive both RF and optical signals. It should be understood that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0052] Although the transmit / receive element 122 is described as a single element in Figure 1B the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can utilize MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (such as multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0053] The transceiver 120 can be configured to modulate the signals to be transmitted by the transmit / receive element 122 and demodulate the signals received by the transmit / receive element 122. As described above, the WTRU 102 can have multi-mode capabilities. Thus, the transceiver 120 can include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11).

[0054] The processor 118 of the WTRU 102 can be coupled to a speaker / microphone 124, a keyboard 126, and / or a display / touchpad 128 (such as a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and can receive user input data therefrom. The processor 118 can also output user data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. In addition, the processor 118 can access information from any type of suitable memory (such as non-removable memory 130 and / or removable memory 132), and store data in these memories. The non-removable memory 130 can include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and so on. In other embodiments, the processor 118 can access information from memories that are not physically located on the WTRU 102 (such as located on a server or a home computer (not shown)), and store data therein.

[0055] The processor 118 can receive power from a power source 134, and can be configured to distribute and / or control power for other components in the WTRU 102. The power source 134 can be any suitable device for powering the WTRU 102. For example, the power source 134 can include one or more dry batteries (such as nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and so on.

[0056] The processor 118 can also be coupled to a GPS chipset 136, which can be configured to provide location information (such as longitude and latitude) about the current location of the WTRU 102. As a supplement or replacement to the information from the GPS chipset 136, the WTRU 102 can receive location information from a base station (such as base stations 114a, 114b) via an 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 understood that while remaining compliant with the embodiments, the WTRU 102 can obtain location information by means of any suitable location determination method.

[0057] The processor 118 can also be coupled to other peripheral devices 138, which can 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 can include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, Modules, FM radio units, digital music players, media players, video game console modules, Internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripheral device 138 may include one or more sensors. The sensors may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[0058] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate self-interference via hardware (e.g., a choke) or via signal processing by a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with a particular subframe for UL (e.g., for transmission) or DL (e.g., for reception)).

[0059] Figure 1C is a system diagram showing a RAN 104 and a CN 106 according to an embodiment. As described above, the RAN 104 may communicate with the WTRU 102a, 102b, 102c via the air interface 116 using E-UTRA radio technology. The RAN 104 may also communicate with the CN 106.

[0060] The RAN 104 may include eNode-Bs 160a, 160b, 160c, but it should be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiment. Each of the eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRU 102a, 102b, 102c via the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to the WTRU 102a and / or receive wireless signals from the WTRU 102a.

[0061] Each of eNode-Bs 160a, 160b, and 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 UL and / or DL, etc. As Figure 1C shown, eNode-Bs 160a, 160b, and 160c may communicate with each other via the X2 interface.

[0062] 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 elements are depicted as part of CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0063] MME 162 may be connected to each of eNode-Bs 162a, 162b, and 162c in RAN 104 via the S1 interface and may serve as a control node. For example, MME 162 may be responsible for authenticating users of WTRUs 102a, 102b, and 102c, bearer activation / deactivation, selecting a particular serving gateway during the initial attachment of WTRUs 102a, 102b, and 102c, etc. MME 162 may provide control plane functions for handover between RAN 104 and other RANs (not shown) utilizing other radio technologies such as GSM and / or WCDMA.

[0064] SGW 164 may be connected to each of eNode-Bs 160a, 160b, and 160c in RAN 104 via the S1 interface. SGW 164 may generally route and forward user data packets to / from WTRUs 102a, 102b, and 102c. SGW 164 may perform other functions such as anchoring the user plane during handover between eNode Bs, triggering paging when DL data is available for WTRUs 102a, 102b, and 102c, managing and storing the context of WTRUs 102a, 102b, and 102c, etc.

[0065] SGW 164 may be connected to PGW 166, and PGW 166 may provide access for WTRUs 102a, 102b, and 102c to a packet switched network such as the Internet 110 to facilitate communication between WTRUs 102a, 102b, and 102c and IP-enabled devices.

[0066] CN 106 can facilitate communication with other networks. For example, CN 106 can provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network such as the PSTN 108 to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, CN 106 can include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and the PSTN 108. Additionally, CN 106 can provide the WTRUs 102a, 102b, 102c with access to other networks 112, which can include other wired and / or wireless networks owned and / or operated by other service providers.

[0067] Although the WTRU is described in Figures 1A to 1D as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal can use (e.g., temporarily or permanently) a wired communication interface with a communication network.

[0068] In a representative embodiment, other network 112 can be a WLAN.

[0069] A WLAN employing an Infrastructure Basic Service Set (BSS) mode can have an Access Point (AP) for the BSS and one or more Stations (STAs) associated with the AP. The AP can have access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic going to an STA from outside the BSS can arrive via the AP and can be delivered to the STA. Traffic going from an STA to a destination outside the BSS can be sent to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS can be sent through the AP. For example, where the source STA can send traffic to the AP and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between a source STA and a destination STA (e.g., directly between the source STA and the destination STA) using Direct Link Setup (DLS). In certain representative embodiments, DLS can use 802.11e DLS or 802.11z Tunnel DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode can not have an AP, and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode can sometimes be referred to herein as an "ad-hoc" communication mode.

[0070] When operating in 802.11ac infrastructure mode or a similar operating mode, the AP can send beacons on a fixed channel (e.g., the primary channel). The primary channel can be of a fixed width (e.g., 20 MHz bandwidth) or dynamically set width. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, the STA (e.g., each STA) (including the AP) can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that particular STA can back off. Only one STA (e.g., only one station) can transmit at any given time in a given BSS.

[0071] High Throughput (HT) STAs can communicate using a 40 MHz wide channel, e.g., by combining a 20 MHz primary channel with an adjacent or non - adjacent 20 MHz channel to form a 40 MHz wide channel.

[0072] Very High Throughput (VHT) STAs can support channels that are 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide. The 40 MHz and / or 80 MHz channels can be formed by combining consecutive 20 MHz channels. The 160 MHz channel can be formed by combining eight consecutive 20 MHz channels or by combining two non - consecutive 80 MHz channels, which can be referred to as the 80 + 80 configuration. For the 80 + 80 configuration, the data after channel coding can be passed through a segment parser, which can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time - domain processing can be performed on each stream separately. The streams can be mapped to two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80 + 80 configuration can be reversed, and the combined data can be sent to the Medium Access Control (MAC).

[0073] Sub-1GHz operation modes are supported by 802.11af and 802.11ah. The channel operation bandwidth and carrier in 802.11af and 802.11ah are reduced compared to those used in 802.11n and 802.11ac. 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 a macro coverage area. MTC devices can have certain capabilities, such as including (e.g., only including) limited capabilities that support certain and / or limited bandwidths. MTC devices can include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0074] WLAN systems (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) that can support multiple channels and channel bandwidths include channels that can be designated as the primary channel. The primary channel can have a bandwidth equal to the maximum common operation bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or restricted by the STA that supports the minimum bandwidth operation mode among all STAs operating in the BSS. In the example of 802.11ah, for an STA that supports (e.g., only supports) the 1MHz mode (e.g., an MTC type device), the primary channel can be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) settings can depend on the state of the primary channel. If the primary channel is busy, for example, due to an STA (which only supports the 1MHz operation mode) sending to the AP, then all available bands can be considered busy even if most of the available bands remain idle.

[0075] In the United States, the available bands that 802.11ah can use are from 902MHz to 928MHz. In Korea, the available bands are from 917.5MHz to 923.5MHz. In Japan, the available bands are from 916.5MHz to 927.5MHz. Depending on the country code, the total bandwidth available for 802.11ah is from 6MHz to 26MHz.

[0076] Figure 1DFIG. 0 shows a system diagram of RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 may communicate with WTRUs 102a, 102b, 102c via air interface 116 using NR radio technology. RAN 104 may also communicate with CN 106.

[0077] RAN 104 may include gNBs 180a, 180b, 180c, but it should be understood that RAN 104 may include any number of gNBs while remaining consistent with the embodiment. Each of gNBs 180a, 180b, 180c may include one or more transceivers for communicating with WTRUs 102a, 102b, 102c via air interface 116. In one embodiment, gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, 180c. Thus, for example, gNB 180a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from WTRU 102a. In an embodiment, gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers (not shown) to WTRU 102a. A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive a coordinated transmission from gNB 180a and gNB 180b (and / or gNB 180c).

[0078] WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or the OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different parts of the radio transmission spectrum. WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing a varying number of OFDM symbols and / or having a continuously varying absolute time length).

[0079] gNBs 180a, 180b, 180c can be configured to communicate with WTRUs 102a, 102b, 102c in a stand-alone configuration and / or a non-stand-alone configuration. In the stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c without accessing another RAN (e.g., such as eNode-Bs 160a, 160b, 160c). In the stand-alone configuration, WTRUs 102a, 102b, 102c can utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor. In the stand-alone configuration, WTRUs 102a, 102b, 102c can communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In the non-stand-alone configuration, WTRUs 102a, 102b, 102c can communicate / connect with gNBs 180a, 180b, 180c while also communicating / connecting with another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c can implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-stand-alone configuration, eNode-Bs 160a, 160b, 160c can be used as a mobility anchor for WTRUs 102a, 102b, 102c, and gNBs 180a, 180b, 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, 102c.

[0080] Each of gNBs 180a, 180b, 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support network slicing, DC, interworking between NR and E-UTRA, routing of user plane data to user plane functions (UPFs) 184a, 184b, routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As Figure 1D shown, gNBs 180a, 180b, 180c can communicate with each other via the Xn interface.

[0081] Figure 1DThe illustrated CN 106 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 data networks (DN) 185a, 185b. Although the foregoing elements are depicted as part of CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0082] 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 WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, managing the registration area, terminating non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize the CN support for the WTRUs 102a, 102b, 102c based on the type of service the WTRUs 102a, 102b, 102c are using. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low-latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 182a, 182b may provide control plane functions for handovers between the RAN 104 and other RANs (not shown) that employ other radio technologies (e.g., LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi).

[0083] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via an N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic 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, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0084] UPF 184a and 184b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 104 via the N3 interface. The N3 interface can provide access to a packet-switched network such as the Internet 110 for WTRU 102a, 102b, and 102c to facilitate communication between WTRU 102a, 102b, and 102c and IP-enabled devices. UPF 184a and 184b can perform other functions such as routing and forwarding packets, implementing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0085] CN 106 can facilitate communication with other networks. For example, CN 106 can include or communicate with an IP gateway (such as an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and the PSTN 108. In addition, CN 106 can provide access to other networks such as other network 112 for WTRU 102a, 102b, and 102c. The other network 112 can include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU 102a, 102b, and 102c can be connected to local DNs 185a and 185b via the N3 interface to UPF 184a and 184b and the N6 interface between UPF 184a and 184b and DNs 185a and 185b.

[0086] In view of Figures 1A to 1D and with respect to Figures 1A to 1D the corresponding descriptions herein, one or more or all of the functions described herein for one or more of WTRU 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DNs 185a-b, and / or any other one or more of the devices described herein can be performed by one or more emulation devices (not shown). The emulation devices can be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices can be used to test other devices and / or simulate network and / or WTRU functions.

[0087] A simulation device can be designed to implement one or more tests on other devices in a laboratory environment and / or an operator network environment. For example, one or more simulation devices can perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more simulation devices can perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. A simulation device can be directly coupled to another device to perform tests and / or execute tests using over-the-air wireless communication.

[0088] One or more simulation devices can perform one or more functions including all functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, a simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., test) wired and / or wireless communication network to implement tests on one or more components. One or more simulation devices can be test devices. A simulation device can send and / or receive data using direct RF coupling and / or wireless communication via an RF circuit (e.g., which can include one or more antennas).

[0089] The following abbreviations and acronyms may be referred to:

[0090] ACK Acknowledgment

[0091] BWP Bandwidth Part

[0092] CC Component Carrier

[0093] CCG Component Carrier Group

[0094] CE Control Element

[0095] CRC Cyclic Redundancy Check

[0096] CSI Channel State Information

[0097] DCI Downlink Control Information

[0098] DMRS Demodulation Reference Signal

[0099] DL Downlink

[0100] HARQ Hybrid Automatic Repeat Request

[0101] IE Information Element

[0102] LTE Long Term Evolution

[0103] MAC Medium Access Control

[0104] MIB Master Information Block

[0105] NACK Negative Acknowledgment

[0106] NR New Radio

[0107] PIR Packet Internal Reception

[0108] PRB Physical Resource Block

[0109] PRR Packet Reception Ratio

[0110] PSBCH Physical Sidelink Broadcast Channel

[0111] PSCCH Physical Sidelink Control Channel

[0112] PSFCH Physical Sidelink Feedback Channel

[0113] PSSCH Physical Sidelink Shared Channel

[0114] QoS Quality of Service

[0115] RAN Radio Access Network

[0116] RB Resource Block

[0117] RBG Resource Block Group

[0118] RNTI Radio Network Temporary Identifier

[0119] RRC Radio Resource Control

[0120] RSRP Reference Signal Received Power

[0121] RSU Road Side Unit

[0122] S-SSB Sidelink Synchronization Signal Block

[0123] S-RSRP Sidelink Reference Signal Received Power

[0124] S-RSSI Sidelink Received Signal Strength Indicator

[0125] SCI Sidelink Control Information

[0126] SFI Slot Format Indicator

[0127] SI System Information

[0128] SINR Signal-to-Interference-plus-Noise Ratio

[0129] SL Sidelink

[0130] SNR Signal-to-Noise Ratio

[0131] TCI Transmission Configuration Indication

[0132] TB Transport Block

[0133] UE User Equipment

[0134] UL Uplink

[0135] V2V Vehicle-to-Vehicle

[0136] V2X Vehicle-to-Everything

[0137] Figure 2 Examples of 5G NR V2X requirements and LTE V2V requirements are shown. The most demanding set of requirements is a maximum sidelink range of 1000 m, a maximum throughput of 1 Gbps, a shortest latency of 3 ms, a maximum reliability of 99.999%, and a maximum transmission rate of 100 messages per second. Other challenging requirements can also include relative mobility speed and positioning accuracy. However, there is no use case that inherently requires all of these boundary requirements. There are also requirements related to security, integrity, authorization, and privacy.

[0138] 5G NR V2X has physical layer support for broadcast, unicast, and multicast sidelink operations. The addition of unicast and multicast is associated with the introduction of sidelink HARQ feedback, higher-order modulation, sidelink CSI, and PC5-RRC.

[0139] The 5G NR V2X sidelink uses the following physical channels and signals: Physical Sidelink Broadcast Channel (PSBCH) and its DMRS; Physical Sidelink Control Channel (PSCCH) and its DMRS; Physical Sidelink Shared Channel (PSSCH) and its DMRS; Physical Sidelink Feedback Channel (PSFCH); Sidelink Primary Synchronization Signal and Secondary Synchronization Signal (S-PSS and S-SSS), which are organized together with the PSBCH into a Sidelink Synchronization Signal Block (S-SSB), where S-PSS and S-SSS can be collectively referred to as Sidelink Synchronization Signal (SLSS); Phase Tracking Reference Signal (PT-RS) in FR2; and Channel State Information Reference Signal (CSI-RS).

[0140] The 5G NR-V2X sidelink supports subcarrier spacings of 15, 30, 60, and 120 kHz. Their association with the CP and frequency range is the same as that of NR UL / DL, but only the CP-OFDM waveform is used. The available modulation schemes are QPSK, 16-QAM, 64-QAM, and 256-QAM.

[0141] The PSBCH transmits the SL-BCH transport channel, which carries the sidelink V2X Master Information Block (MIB-V2X) from the RRC layer. When in use, the PSBCH transmits the MIB-V2X in 11 RBs of the SL bandwidth every 160 ms, with possible repetitions in this period. The DMRS associated with the PSBCH is transmitted in each symbol of the S-SSB time slot. The S-PSS and S-SSS are transmitted together with the PSBCH in the S-SSB. They jointly convey the SLSSID used by the UE.

[0142] The sidelink control information (SCI) in 5G NR V2X is transmitted in two phases. The first-phase SCI is carried on the PSCCH and includes information enabling the sensing operation and information on the resource allocation of the PSSCH.

[0143] The PSSCH transmits the second-phase SCI and the SL-SCH transport channel. The second-phase SCI carries the information required to identify and decode the associated SL-SCH, as well as the control for the HARQ process, and the trigger for CSI feedback, etc. The SL-SCH carries the TB for the data transmitted over the sidelink.

[0144] The resources in which the PSSCH is transmitted can be scheduled or configured by the gNB, or determined through a sensing process autonomously performed by the transmitting UE. A given TB can be transmitted multiple times. The DMRS associated with rank-1 or rank-2 PSSCH can be transmitted in 2, 3, or 4 sidelink symbols distributed over the sidelink time slot. The multiplexing between the PSCCH and the PSSCH can be in time and frequency within the time slot.

[0145] The PSFCH carries the HARQ feedback from the UE (referred to as the RxUE in this document) that is the intended receiver of the PSSCH transmission to the UE (referred to as the Tx UE in this document) that performs the transmission, over the sidelink. The sidelink HARQ feedback can be in the form of a regular ACK / NACK or only NACK, where nothing is transmitted in the case of successful decoding. The PSFCH transmits a Zadoff-Chu sequence repeated on two OFDM symbols in one PRB, where the first OFDM symbol can be used for AGC, near the end of the sidelink resources in the time slot. The time resources for the PSFCH are configured / pre-configured to occur once every 1, 2, or 4 time slots.

[0146] Resource Allocation Mode 1 can be used for the resource allocation by the gNB. Use cases intended for 5G NR V2X can generate different arrays of periodic and aperiodic message types. Therefore, Resource Allocation Mode 1 provides dynamic authorization of sidelink resources from the gNB, as well as authorization of periodic sidelink resources semi-statically configured by the RRC.

[0147] The dynamic sidelink grant DCI can provide resources for one or more transmissions of transport blocks to allow control of reliability. If the sidelink HARQ process is enabled, the (one or more) transmissions can be subject to the sidelink HARQ process.

[0148] The configured sidelink grant can be such that it is configured once and can be used immediately by the UE until it is released by RRC signaling (referred to as type 1). When a beam failure or a physical layer problem occurs in NR Uu, the UE is allowed to continue using this type of configured sidelink grant until the RLF detection timer expires and then fallback to the abnormal resource pool. Another type of configured sidelink grant (referred to as type 2) is configured once but cannot be used until the gNB sends a DCI indicating that it is now active, and only until another DCI indicates deactivation. The two types of resources are sets of sidelink resources that the gNB will expect to match the characteristics of V2X services with periodic recurrence. Multiple configured grants can be configured to allow provision of different services, traffic types, etc.

[0149] The MCS information for dynamic and configured grants can optionally be provided or constrained by RRC signaling instead of traditional DCI. The RRC can configure the exact MCS or the range of MCS that the Tx UE uses. It can also not be configured. For the case where the RRC does not provide the exact MCS, the Tx UE selects the appropriate MCS itself based on the knowledge of the TB it has to transmit and the potential sidelink radio conditions.

[0150] Resource allocation mode 2 can be used for UE autonomous resource selection. Its basic structure is that the UE senses within a (pre)-configured resource pool which resources are not being used by other UEs with higher priority traffic and selects an appropriate amount of such resources for its own transmission. After such resources are selected, the UE can send and retransmit a specific number of times within them, or until the reason for triggering resource reselection.

[0151] The mode 2 sensing process can select and subsequently reserve resources for various purposes, reflecting that NR V2X introduces sidelink HARQ to support unicast and multicast in the physical layer. It can reserve resources to be used for multiple blind (re)transmissions or HARQ feedback-based (re)transmissions of transport blocks, in which case the resources are indicated in the (one or more) SCI(s) scheduling the transport block. Alternatively, it can select resources to be used for the initial transmission of a later transport block, in which case the resources are indicated in the SCI scheduling the current transport block. Finally, the initial transmission of the transport block can be performed after sensing and resource selection, but without reservation.

[0152] The first-phase SCI sent by the UE on the PSCCH indicates the time-frequency resources in which the UE will send the PSSCH. The sensing UE uses these SCI transmissions to maintain a record of which resources have been recently reserved by other UEs.

[0153] Then, the sensing UE can select resources for its (re)transmission from within a resource selection window. The window can start shortly after the trigger for the (re)selection of resources and cannot be longer than the remaining delay budget for the packet being sent. Reserved resources in the selection window with an SL-RSRP higher than a threshold are excluded from candidates by the sensing UE, where the threshold is set according to the priorities of the services of the sensing UE and the transmitting UE. Thus, higher-priority transmissions from the sensing UE can occupy resources reserved by a Tx UE with a sufficiently low SL-RSRP and a sufficiently low-priority service.

[0154] The BWP is defined for the sidelink in a similar way to UL / DL to provide a convenient way to specify aspects related to the UE RF hardware chain implementation. When in the connected mode to the gNB, the UE can be configured with an active sidelink BWP, which is the same as a single sidelink BWP for idle mode or out-of-coverage operation.

[0155] The subcarrier spacing used on the sidelink is provided in the sidelink BWP (pre)configuration, which is from the same set of values as the Uu interface and the association with the frequency range (i.e., 15, 30, or 60 kHz for FR1, and 60 or 120 kHz for FR2). Thus, the sidelink transmission and reception of the UE are contained within the sidelink BWP, and the same sidelink BWP is used for both transmission and reception. This means that from the UE's perspective, the resource pool, S-SSB, etc. must also be contained within the appropriate sidelink BWP.

[0156] To support a wide range of services, the 5G NR system is designed to be flexible enough to meet the connectivity requirements of a series of existing and future (unknown) services that will be deployed in an efficient manner. Specifically, NR considers supporting the potential use of frequency ranges up to 100 GHz.

[0157] The 5G NR specifications developed in Rel-15 and Rel-16 define operations for frequencies up to 52.6 GHz, where all physical layer channels, signals, processes, and protocols are designed to be optimized for use below 52.6 GHz.

[0158] However, compared to lower frequency bands, frequencies above 52.6 GHz face more difficult challenges, such as higher phase noise, larger propagation losses due to high atmospheric absorption, lower power amplifier efficiency, and stringent power spectral density regulatory requirements in unlicensed bands. Additionally, the frequency range above 52.6 GHz may contain larger spectrum allocations and larger bandwidths that are not available for bands below 52.6 GHz.

[0159] As a preliminary effort to enable and optimize 3GPP 5G NR systems to operate above 52.6 GHz, 3GPP RAN has studied the requirements for NR above 52.6 GHz up to 114.25 GHz, including global spectrum availability and regulatory requirements (including channelization and licensing regimes), potential use cases and deployment scenarios, and considerations above NR system design requirements and regulatory requirements. The potential use cases identified in the study include high data rate eMBB, mobile data offloading, short-range high data rate D2D communication, broadband distribution networks, integrated access backhaul (IAB), factory automation, industrial IoT (IIoT), wireless display delivery, augmented reality (AR) / virtual reality (VR) wearables, intelligent transportation systems (ITS) and V2X, inter-rack connections in data centers, smart grid automation, private networks, and support for high positioning accuracy. The use cases span several deployment scenarios identified in the study. The deployment scenarios include, but are not limited to, indoor hotspots, dense urban, urban micro, urban macro, rural, factor hall, and indoor D2D scenarios. The study has also identified several system design requirements regarding waveforms, MIMO operation, device power consumption, channelization, bandwidth, range, availability, connectivity, spectrum condition considerations, etc.

[0160] Among the frequencies of interest, the frequencies between 52.6 GHz and 71 GHz are relatively particularly interesting in the short term because they are close to the sub-52.6 GHz for which current NR systems are optimized, as well as upcoming commercial opportunities for high data rate communication, e.g., unlicensed spectrum and licensed spectrum between 57 GHz and 71 GHz.

[0161] 5G NR rel-15 defines two frequency ranges for operation: FR1 that spans from 410 MHz to 7.125 GHz, and FR2 that spans from 24.25 GHz to 52.6 GHz.

[0162] The proximity of this frequency range (57 - 71 GHz) to FR2 and the upcoming commercial opportunities for high data rate communications make it attractive for 3GPP to address NR operation in this frequency range. To minimize the specification burden and maximize the utilization of FR2-based implementations, 3GPP has decided to extend FR2 operation up to 71 GHz by adopting one or more new parameter sets (i.e., larger subcarrier spacings). The one or those new parameter sets will be identified through the study of waveforms for NR > 52.6 GHz. The NR-U defined procedures for operation in unlicensed spectrum will also be utilized for operation in the unlicensed 60 GHz band. NR operation can support up to 71 GHz. Considering licensed and unlicensed operations, similar to the conventional NR and NR-U operations below 52.6 GHz, the NR / NR-U operations in the 52.6 GHz to 71 GHz range can be stand-alone or aggregated with an anchor carrier via CA or DC.

[0163] In Release 16 New Radio Unlicensed (NR-U), the supported parameter sets (i.e., subcarrier spacings (SCS)) are set to 15, 30, and 60 kHz respectively. In Release 16 NR-U, the Listen-Before-Talk (LBT) bandwidth is set to 20 MHz. Based on the minimum LBT bandwidth that must be supported, for rel-16 NR-U, the DL initial BWP is nominally 20 MHz. The maximum supported channel bandwidth is set to 100 MHz. The UE channel bandwidth (or the activated BWP) can be set to an integer multiple of the LBT bandwidth (i.e., 20 MHz). For example, for SCS = 30 kHz, the total allocated PRB counts for 20 MHz, 40 MHz, and 80 MHz bandwidths are equal to 48, 102, and 214 respectively.

[0164] Rel-18 will cover sidelink communications with FR1 unlicensed channel access for mode 2 (without beam management) and FR2 licensed operation with beam management. However, for FR1 only unlicensed channel access and physical channel design are considered, and for licensed spectrum only beam management is considered. FR2 unlicensed operation with beam management is not considered in Rel-18. Additionally, only unicast communications are considered. Other broadcast types are not considered. Different broadcast types including multicast are considered in this disclosure.

[0165] In beam-based SL in an unlicensed band, due to channel uncertainty, a signal / channel may not be transmitted due to LBT failure in a certain spatial direction. Even if a signal / channel can be transmitted in a certain spatial direction, the signal / channel may not be received due to interference (e.g., from a hidden node in a certain spatial direction). To address this issue, a process for increasing transmission and / or reception opportunities is needed in an unlicensed beam-based SL system. Due to the unique two-stage control design in SL, it is necessary to consider how to incorporate the TCI framework into SL to increase transmission and / or reception opportunities in the unlicensed spectrum.

[0166] In multicast, only NACK HARQ feedback is supported. In an unlicensed band, if a NACK is not received, the Tx UE may assume an ACK. In an unlicensed band, due to channel uncertainty, a NACK may not be transmitted, in which case the Tx UE may assume that the Rx UE has successfully received the PSSCH. This results in system errors and performance degradation. It is necessary to consider how to incorporate TCI to solve this problem in multicast. A process is needed to solve this problem and improve performance. In a beam-based unlicensed band, in addition to the frequency domain-time domain, it also has an additional dimension in the spatial domain, and resource selection may be affected by channel uncertainty and the spatial domain. In a beam-based unlicensed band, it is necessary to consider how to incorporate the spatial domain into resource selection.

[0167] To address the above and other issues, in some aspects, the present disclosure relates to systems and methods for mode 2 operation of sidelink (SL) beam-based hybrid automatic repeat request (HARQ). A hybrid acknowledgement / negative acknowledgement (ACK / NACK) scheme can be used, where an ACK is used in addition to (or instead of, depending on the implementation) the NACK when the listen-before-talk (LBT) fails or the channel uncertainty (due to noise, interference, low signal level, etc.) is high, and only the NACK scheme is used for high throughput and low latency when the LBT fails or the channel uncertainty is low. In various implementations, the ACK and / or NACK can be grouped or identify multiple received or lost signals, or individual ACKs or NACKs can be utilized (i.e., one ACK or NACK per signal or sequence number). In various implementations, this can similarly be based on channel uncertainty or LBT failure, or any other type and form of channel or device condition or characteristic. Thus, a device can dynamically switch between multiple HARQ configurations in response to changing channel conditions (e.g., ACK / NACK feedback scheme, NACK-only feedback scheme, shared ACK / NACK feedback scheme, etc.). Other HARQ configurations for feedback schemes can also include shared NACK and individual ACK, shared ACK and individual NACK, or any other such combination of shared and / or individual ACK and / or NACK. A HARQ feedback scheme with shared NACK and individual ACK can include a feedback scheme having a NACK resource shared by multiple SL WTRUs and non-shared ACK resources; conversely, in such an implementation, the ACK resources are separate and the ACK resources are used individually by multiple SL WTRUs, where each ACK resource is dedicated to one SL WTRU. In other implementations, a HARQ feedback scheme with shared ACK and individual NACK can include a feedback scheme having an ACK resource shared by multiple SL WTRUs and non-shared NACK resources; conversely, the NACK resources are separate and the NACK resources are used individually by multiple SL WTRUs, where each NACK resource is dedicated to one SL WTRU. Various other implementations can include partially shared NACK and individual ACK; partially shared ACK and individual NACK; or partially shared NACK and ACK. In an implementation of a feedback scheme using partially shared NACK and individual ACK, more than one NACK resource can be used for multiple SL WTRUs, and some SL WTRUs can share a single NACK resource. For example, a first subset of SL WTRUs can use a first NACK resource, and a second subset of SL WTRUs can use a different second NACK resource.Similarly, in implementations of feedback schemes using partially shared ACKs and separate NACKs, more than one ACK resource can be used for multiple SL WTRUs, and some SL WTRUs can share a single ACK resource. For example, a first subset of SL WTRUs can use a first ACK resource, and a second subset of SL WTRUs can use a different second ACK resource. In implementations of feedback schemes using partially shared NACKs and ACKs, more than one NACK resource and more than one ACK resource can be used for multiple SL WTRUs, where some SL WTRUs share a single NACK resource and some SL WTRUs (the same or different WTRUs) share a single ACK resource. For example, a first subset of SL WTRUs can use a first NACK resource, and a second subset of SL WTRUs can use a different second NACK resource, and a third subset of SL WTRUs can use a first ACK resource, and a fourth subset of SL WTRUs can use a different second ACK resource. The first and third subsets of SL WTRUs can be the same or different (including overlapping subsets or completely disjoint subsets), and the second and fourth subsets of SL WTRUs can be the same or different (including overlapping subsets or completely disjoint subsets). For example, a first SL WTRU can be in a first subset using a first shared NACK resource with a second SL WTRU, but can also be in a second subset (excluding the second SL WTRU) using a first shared ACK resource with a third SL WTRU. Thus, in various implementations, any combination of SL WTRUs can use shared resources.

[0168] The UE can perform sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback.

[0169] The UE can be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). The UE can be configured or pre-configured with multiple HARQ feedback schemes (e.g., ACK / NACK, NACK-only, etc.).

[0170] The UE can be indicated or provided with (one or more) TCIs to transmit PSFCH transmissions using the (one or more) beams associated with the (one or more) TCIs. If the channel uncertainty is greater than a first threshold, the UE can be indicated to use a large TCI set (e.g., (one or more) P-TCIs and / or (one or more) S-TCIs). If the channel uncertainty is greater than a second threshold, the UE can switch to a HARQ feedback scheme based on separate ACK / NACKs.

[0171] The UE may be instructed to send a separate ACK or NACK based on the decoding result. If the channel uncertainty is not greater than a second threshold, the UE may switch to a NACK-only HARQ feedback scheme. The UE may be instructed to send a NACK only when decoding fails. If the channel uncertainty is greater than a first threshold, the UE may be instructed to use a small TCI set (e.g., only (one or more) P-TCIs). If the channel uncertainty is greater than a third threshold, the UE may switch to a HARQ feedback scheme based on separate ACK / NACKs. The UE may be instructed to send a separate ACK or NACK based on the decoding result.

[0172] If the channel uncertainty is not greater than a first threshold, the UE may switch to a NACK-only HARQ feedback scheme. The UE may be instructed to send a NACK only when decoding fails.

[0173] In an embodiment, a method for beam-based mode 2 operation for HARQ and multicast in unlicensed shared spectrum is disclosed. In multicast, NACK-only HARQ feedback is supported. In an unlicensed band, if a NACK is not received, the Tx UE may assume an ACK. In an unlicensed band, due to channel uncertainty, a NACK may not be sent. The Tx UE may assume that the Rx UE has successfully received the data. However, the Rx UE may not have successfully received the data. This may lead to performance degradation.

[0174] In some embodiments, when the LBT failure is high, HARQ can switch to an ACK / NACK-based process and switch back to a NACK-only process when the LBT failure is low. In some embodiments, more than one PSFCH resource can be used to increase the transmission opportunity of NACK-only feedback. Currently, only one NACK-only resource is used. Such embodiments can use more than one PSFCH resource (in time, frequency, or combination) for NACK-only transmission. An adaptive reconfiguration or dynamic indication for the RP (e.g., resource period or repetition period) can be used with a method of using a small number instead of a large number. In some embodiments, more than one beam can be used to send PSFCH NACK-only. In addition to the primary PSFCH beam, a secondary PSFCH beam can also be used. This can be used in combination with other methods described herein. In some embodiments, an SL-SCI with multiple received TCIs (PSCCH / PSSCH) having primary / secondary TCIs in the code points of the SL MAC CE can be utilized. The primary / secondary TCIs can be associated with the member ID of the group. The primary / secondary TCIs can be associated with different beams, beam widths, beam parameters, beam characteristics, etc. For example, the primary TCI can be associated with a wide beam, while the secondary TCI can be associated with a narrow beam or a sub-beam, and vice versa. In another example, the primary TCI can be associated with a beam having high quality (e.g., beam or link quality) or quality of service (QoS), and the secondary TCI can be associated with a beam having medium or low quality (e.g., beam or link quality) or quality of service (QoS), or vice versa. More than one PSFCH resource can be used for ACK and / or NACK. In addition, the ACK and / or NACK resources can be shared by multiple UEs, and more than one PSFCH resource can be used for shared ACK and / or NACK.

[0175] For shared ACK and NACK, if the Rx UE does not send a NACK or the Tx UE does not receive a NACK, an ACK may not be assumed. This is different from the NACK-only method where an ACK can be assumed. The UE also expects a shared ACK. If only the shared ACK is received, an ACK is assumed. If neither the shared ACK nor the NACK is received, a NACK can be assumed. If both the shared ACK and the NACK are received, a NACK can be assumed.

[0176] Another alternative can be to use a common or shared NACK but individual ACKs or a common or shared ACK but individual NACKs. Some partitioning or sub-packeting of ACK and / or NACK is also possible.

[0177] A hybrid process using TCI and shared ACK / NACK can be used. If the channel uncertainty is high, a large set of TCI and ACK / NACK-based can be used. If the channel uncertainty is moderately high, a large set of TCI and shared ACK / NACK can be used. If the channel uncertainty is moderately low, a small set of TCI and shared ACK / NACK can be used. If the channel uncertainty is low, a small set of TCI and NACK only can be used.

[0178] Figure 3 An example method of HARQ feedback based on sidelink TCI is shown. At 302, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). Additionally, at 304, the UE may be configured or pre-configured with multiple HARQ feedback schemes or processes (e.g., ACK / NACK, NACK only, shared ACK / NACK, etc.). At 306, the UE may be configured or pre-configured with multiple HARQ feedback resources.

[0179] At 308, the channel uncertainty can be determined based on (one or more) measurements and (one or more) thresholds. At 310, the TCI type and TCI set can be selected based on the channel uncertainty. At 310, the HARQ feedback scheme can also be determined based on the channel uncertainty in combination with the TCI type and TCI set. The HARQ feedback resource can be determined based on the channel uncertainty in combination with the determined TCI type and TCI set and the selected HARQ feedback scheme. At 312, the UE can send HARQ feedback via the PSFCH using the indicated (one or more) TCI, the selected HARQ feedback scheme, and the feedback resource.

[0180] Figure 4An example method for sidelink TCI-based HARQ feedback is shown. At 402, the UE may be configured or pre-configured with multiple types of TCI and multiple TCI sets (e.g., one or more primary TCIs (P-TCIs) and / or one or more secondary TCIs (S-TCIs)). At 404, the UE may be indicated the type of TCI, the TCI set, and the (one or more) TCIs to be sent on the PSFCH. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction of the Tx UE to the RX beam.

[0181] At 406, the UE may perform measurements and determine the channel uncertainty. If the channel uncertainty is high, the UE may be indicated at 414 to use two types of TCI (e.g., P-TCI and S-TCI). The UE may be indicated to use a large TCI set for the (one or more) P-TCIs and / or the (one or more) S-TCIs. At 416, the UE may switch to an ACK / NACK-based HARQ scheme and perform an ACK / NACK-based HARQ process. At 418, the UE may be indicated to send an ACK or NACK based on the decoding result. If the decoding is successful, the UE may send an ACK, or if the decoding is unsuccessful or fails, the UE may send a NACK.

[0182] If the channel uncertainty is low, at 408, the UE may be indicated to use a single type of TCI (e.g., only P-TCI). The UE may be indicated to use a small TCI set for the P-TCI. At 410, the UE may switch to a NACK-only HARQ scheme and perform a NACK-only HARQ process. At 412, the UE may send a NACK only if the decoding is unsuccessful or fails. If the decoding is successful, the UE may not send anything.

[0183] Some conditions and / or criteria can be used to determine whether different types or additional (one or more) TCIs can be indicated and used, and whether different HARQ feedback schemes can be selected and switched. One or more thresholds can be used. Thresholds can be used to determine channel uncertainty. For example, if the number of LBT failures is higher than a threshold, it can be determined that the channel uncertainty is high; otherwise, it can be determined that the channel uncertainty is low. For another example, if the measured interference level is higher than a threshold, it can be determined that the channel uncertainty is high; otherwise, it can be determined that the channel uncertainty is low. For another example, if the channel busy ratio (CBR) is higher than a threshold, it can be determined that the channel uncertainty is high; otherwise, it can be determined that the channel uncertainty is low.

[0184] Different thresholds associated with different channel uncertainty measurements and / or metrics can be used. Multiple thresholds can also be considered and utilized. Different conditions and / or criteria can be used alone or jointly to determine channel uncertainty. One channel uncertainty measurement and / or metric can be used in combination with another channel uncertainty measurement and / or metric to determine channel uncertainty. Channel uncertainty measurements and / or metrics can be one of the following: the number of LBT failures, the ratio of LBT failures to total measurements, the ratio of LBT failures to successes, the ratio of NACKs to ACKs, the percentage of NACKs, CBR, interference level, and so on.

[0185] (One or more) thresholds can be configured, pre-configured, predefined, or indicated.

[0186] Figure 5 Is an example method of sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback. At 502, the UE can be configured or pre-configured with multiple types of TCIs and multiple TCI sets (e.g., one or more P-TCIs and / or one or more S-TCIs). At 504, the type of TCI, the TCI set, and the (one or more) TCIs to be sent on the PSFCH can be indicated to the UE. Alternatively, the UE can derive one or more TCIs of the PSFCH based on the configuration of the corresponding PSSCH. Examples of such a configuration can be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE can derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration can be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration can be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam.

[0187] At 506, the UE can perform measurements and determine channel uncertainty. Channel uncertainty can be measured based on the number of LBT failures, the percentage of LBT failures, the number of NACKs, the percentage of NACKs, the NACK to ACK ratio, the interference level, etc.

[0188] It can be determined with better resolution and granularity than in the Figure 4 method. There can be multiple levels of channel uncertainty. There can be more than two levels of channel uncertainty. For example, the channel uncertainty can be high, medium, or low. For another example, the channel uncertainty can be high, medium-high, medium-low, or low.

[0189] If the channel uncertainty is high, then at 518, the UE can be instructed to use two types of TCI (e.g., P-TCI and S-TCI). The UE can be instructed to use a large TCI set for P-TCI and / or S-TCI. At 520, the UE can switch to an ACK / NACK-based HARQ scheme and perform an ACK / NACK-based HARQ process. At 522, the UE can be instructed to send an ACK or NACK based on the decoding result. If the decoding is successful, the UE can send an ACK, or if the decoding is unsuccessful or fails, the UE can send a NACK.

[0190] If the channel uncertainty is low, then at 508, the UE can be instructed to use a single type of TCI (e.g., P-TCI). The UE can be instructed to use a small TCI set for (one or more) P-TCI. At 510, the UE can switch to a NACK-only HARQ scheme and perform a NACK-only HARQ process. At 512, the UE can send a NACK only when the decoding is unsuccessful or fails.

[0191] If the channel uncertainty is medium, then the TCI type can be further determined. Either only P-TCI or both P-TCI and S-TCI can be used.

[0192] If only P-TCI of the TCI type is used, then at 516, the UE can be instructed to use a small TCI set (e.g., (one or more) P-TCI-only sets). The UE can switch to an ACK / NACK-based HARQ process. The UE can be instructed to send an ACK or NACK based on the decoding result.

[0193] If P-TCI and S-TCI of the TCI type are used, then at 514, the UE can be instructed to use a large TCI set (e.g., (one or more) P-TCI and (one or more) S-TCI). The UE can switch to a NACK-only HARQ process. The UE can be instructed to send a NACK only when the decoding fails or is unsuccessful.

[0194] Figure 6 An example method of sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback is shown.

[0195] At 602, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 604, the UE may also be configured or pre-configured with multiple HARQ feedback schemes (e.g., ACK / NACK feedback scheme, NACK-only feedback scheme, shared ACK / NACK feedback scheme, etc.).

[0196] At 606, available TCI(s) may be used to indicate the UE to transmit on the PSFCH. Alternatively, the UE may derive one or more TCI for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCI for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such configuration may be one or more TCI received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam.

[0197] At 608, the channel uncertainty may be measured and compared with a first threshold. If the channel uncertainty is greater than the first threshold, then at 622, the UE may be instructed to use a large TCI set (e.g., P-TCI(s) and / or S-TCI(s)).

[0198] If at 624 the channel uncertainty is also greater than a second threshold, the UE may switch to a HARQ feedback scheme based on individual ACK / NACK at 626. At 628, the UE may be instructed to send an individual ACK or NACK based on the decoding result.

[0199] If the channel uncertainty is not greater than the second threshold, then at 618, the UE may switch to a HARQ feedback scheme based on shared ACK / NACK. At 620, the UE may be instructed to use a shared resource to send a shared ACK or NACK based on the decoding result.

[0200] If the channel uncertainty is not greater than the first threshold, then at 610, the UE may be instructed to use a small TCI set (e.g., only P-TCI(s)).

[0201] If the channel uncertainty at 612 is not greater than the first threshold but greater than the third threshold, then at 614, the UE may switch to a shared ACK / NACK-based HARQ feedback scheme. At 616, the UE may be instructed to use shared resources to send a shared ACK or NACK based on the decoding result.

[0202] If the channel uncertainty is not greater than the first threshold and the third threshold, then at 618, the UE may switch to a NACK-only HARQ feedback scheme. At 620, the UE may be instructed to send a NACK only when decoding fails.

[0203] The second threshold may be greater than the first threshold. The first threshold may be greater than the third threshold. Different combinations of TCI sets and HARQ feedback schemes may be used accordingly, such as Figure 7 shown, Figure 7 illustrating thresholds 702 - 706. Figure 7 Not necessarily drawn to scale, and in various embodiments, the thresholds may be spaced evenly or unevenly.

[0204] Figure 8 An example method of sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback is shown. At 802, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 804, the UE may be configured or pre-configured with multiple HARQ feedback schemes (e.g., ACK / NACK feedback scheme, NACK-only feedback scheme, etc.).

[0205] At 806, the available TCI(s) may be used to instruct the UE to transmit on the PSFCH. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such a configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam.

[0206] At 808, the channel uncertainty may be measured and compared with the first threshold. If the channel uncertainty is greater than the first threshold, then at 822, the UE may be instructed to use a large TCI set (e.g., P-TCI(s) and / or S-TCI(s)).

[0207] If the channel uncertainty is greater than a first threshold and a second threshold at 824, the UE may switch to a HARQ feedback scheme based on a separate ACK / NACK at 828. At 820, the UE may be instructed to send a separate ACK or NACK based on the decoding result. If the channel uncertainty is not greater than the second threshold, at 826, the UE may switch to a NACK-only HARQ feedback scheme. At 816, the UE may be instructed to send a NACK only when decoding fails.

[0208] If the channel uncertainty is not greater than the first threshold, at 810, the UE may be instructed to use a small TCI set (e.g., only (one or more) P-TCIs).

[0209] If the channel uncertainty is greater than the first threshold and a third threshold 812, at 818, the UE may switch to a HARQ feedback scheme based on a separate ACK / NACK. At 820, the UE may be instructed to send a separate ACK or NACK based on the decoding result. If the channel uncertainty is not greater than the third threshold, at 814, the UE may switch to a NACK-only HARQ feedback scheme. At 816, the UE may be instructed to send a NACK only when decoding fails.

[0210] Figure 9 An example method of sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback is shown. At 902, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 904, the UE may be configured to be pre-configured with multiple HARQ feedback schemes (e.g., ACK / NACK, NACK-only feedback scheme, etc.). At 906, an available (one or more) TCI may be used to instruct the UE to transmit on the PSFCH. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. An example of such a configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam.

[0211] At 908, the channel uncertainty can be measured and compared with a first threshold. If the channel uncertainty is greater than the first threshold, then at 924, the UE can be instructed to use a large TCI set (e.g., (one or more) P-TCIs and / or (one or more) S-TCIs). At 926, the UE can switch to an ACK / NACK-based HARQ feedback scheme. At 928, the UE can be instructed to send an ACK or NACK based on the decoding result. The UE can use the large TCI set and the ACK / NACK-based feedback scheme to enhance the performance in the shared spectrum.

[0212] If the channel uncertainty is not greater than the first threshold, then at 910, a second threshold can be checked. If the channel uncertainty is greater than the second threshold, then at 922, the UE can be instructed to use a small TCI set (e.g., only (one or more) P-TCIs) to reduce overhead. At 926, the UE can switch to an ACK / NACK-based HARQ feedback scheme. At 928, the UE can be instructed to send an ACK or NACK based on the decoding result.

[0213] If the channel uncertainty is not greater than the second threshold, then at 912, a third threshold can be checked. If the channel uncertainty is greater than the third threshold, then at 920, the UE can be instructed to use a large TCI set (e.g., (one or more) P-TCIs and / or (one or more) S-TCIs). At 916, the UE can switch to a NACK-only HARQ feedback scheme. At 918, the UE can be instructed to use a large number of beams to send only NACK when decoding fails.

[0214] If the channel uncertainty is not greater than the third threshold, then at 914, the UE can be instructed to use a small TCI set (e.g., only (one or more) P-TCIs). At 916, the UE can switch to a NACK-only HARQ feedback scheme. At 918, the UE can be instructed to use a small number of beams to send only NACK when decoding fails.

[0215] In this case, the first threshold 1002 can be greater than the second threshold 1004, and the second threshold can be greater than the third threshold 1006, as Figure 10 shown. Figure 10 Not necessarily drawn to scale, and in various embodiments, the thresholds can be spaced evenly or unevenly.

[0216] Figure 11An example method of sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback is shown. At 1102, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 1104, the UE may be configured or pre-configured with multiple HARQ feedback schemes (e.g., individual ACK / NACK, NACK only, shared ACK / NACK, etc.). At 1106, the available (one or more) TCIs may be used to indicate to the UE to transmit on the PSFCH. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam.

[0217] The UE may measure the channel uncertainty as discussed above. At 1108, if the channel uncertainty is not greater than a first threshold, then at 1128, the UE may be instructed to use a small TCI set (e.g., only (one or more) P-TCI). At 1130, the UE may switch to the NACK-only HARQ feedback scheme. At 1132, the UE may be instructed to send a NACK only when decoding fails.

[0218] If the channel uncertainty is greater than the first threshold, then a second threshold may be checked at 1110. If the channel uncertainty is not greater than the second threshold, then at 1126, the UE may be instructed to use a large TCI set (e.g., (one or more) P-TCI and / or (one or more) S-TCI). At 1130, the UE may switch to the NACK-only HARQ feedback scheme. At 1132, the UE may be instructed to send a NACK only when decoding fails.

[0219] If the channel uncertainty is greater than the second threshold, then at 1112, a third threshold may be checked.

[0220] If the channel uncertainty is not greater than the third threshold, then at 1120, the UE may be instructed to use a large TCI set (e.g., (one or more) P-TCI and / or (one or more) S-TCI). At 1122, the UE may switch to the HARQ feedback scheme based on shared ACK / NACK. At 1124, the UE may be instructed to send a shared ACK or NACK based on the decoding result.

[0221] If the channel uncertainty is greater than a third threshold, at 1114, the UE may be instructed to use a large TCI set (e.g., (one or more) P-TCIs and / or (one or more) S-TCIs). At 1116, the UE may switch to a HARQ feedback scheme based on a separate ACK / NACK. At 1118, the UE may be instructed to send a separate ACK or NACK based on the decoding result.

[0222] In this case, the first threshold 1202 may be less than the second threshold 1204, and the second threshold may be less than the third threshold 1206, as Figure 12 shown. Figure 12 Not necessarily drawn to scale, and in various embodiments, the thresholds may be spaced evenly or unevenly.

[0223] A large TCI set or a small set may be predefined. Alternatively, a large TCI set or a small set may be configured or preconfigured.

[0224] The UE may determine the channel uncertainty based on an indication, measurement, or combination.

[0225] Thresholds such as the first threshold, the second threshold, and / or the third threshold may be configured, preconfigured, predefined, or indicated.

[0226] A hybrid scheme using TCI, HARQ feedback, and resource allocation may be used to address channel uncertainty in shared spectrum in the sidelink.

[0227] Figure 13An example method of a hybrid scheme using TCI, HARQ feedback, and resource allocation is shown. At 1302, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 1304, the UE may be configured or pre-configured with multiple HARQ feedback schemes (e.g., ACK / NACK, NACK only, etc.) and multiple sets of HARQ feedback resources. At 1306, the available TCI(s) may be used to indicate to the UE to transmit on the PSFCH. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. An example of such a configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction of the Tx UE to the RX beam.

[0228] At 1308, the channel uncertainty may be measured as discussed above. If the channel uncertainty is greater than a first threshold, then at 1322, the UE may be instructed to use a large TCI set (e.g., P-TCI(s) and / or S-TCI(s)). At 1324, the UE may switch to a HARQ feedback scheme based on individual ACK / NACK.

[0229] At 1326, the channel uncertainty may be checked against a second threshold. If the channel uncertainty is greater than the second threshold, then at 1330, a large set of ACK / NACK resources may be used. If the channel uncertainty is not greater than the second threshold, then at 1328, a small set of ACK / NACK resources may be used. At 1332, the UE may be instructed to send an individual ACK or NACK using the determined ACK / NACK feedback resources based on the decoding result.

[0230] If the channel uncertainty is not greater than the first threshold, then at 1310, the UE may be instructed to use a small TCI set (e.g., P-TCI(s) only). At 1312, the UE may switch to a HARQ feedback scheme based on NACK only.

[0231] At 1324, the channel uncertainty may be checked against a third threshold. If the channel uncertainty is greater than the third threshold, then at 1320, a large set of NACK-only resources may be used.

[0232] If the channel uncertainty is not greater than a third threshold, at 1316, a small set of NACK-only resources can be used. At 1318, if decoding fails, the UE can be instructed to use the determined NACK-only feedback resources to send NACK-only.

[0233] In this case, the second threshold 1404 can be greater than the first threshold 1402. The first threshold can be greater than the third threshold 1406, as Figure 14 shown. Figure 14 Not necessarily drawn to scale, and in various embodiments the thresholds can be spaced evenly or unevenly.

[0234] UE-assisted SL TCI and HARQ feedback can be used. UE-controlled SL TCI and HARQ feedback can also be considered.

[0235] Figure 15 An example method of side-link UE-assisted TCI and HARQ feedback is shown. At 1502, the UE can be configured or pre-configured with multiple sets of TCIs (e.g., P-TCI and / or S-TCI). At 1504, the Tx UE can indicate to the Rx UE one or more TCIs for transmission on the PSFCH. Alternatively, the UE can derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such a configuration can be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE can derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration can be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration can be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction of the Tx UE to the RX beam. At 1506, the Rx UE can perform measurements and report the channel uncertainty to the Tx UE.

[0236] At 1508, the Tx UE can perform measurements and determine the channel uncertainty based on its own measurements and the channel uncertainty report from the Rx UE.

[0237] If the channel uncertainty is high at 1510, at 1518 the Rx UE can be instructed to use a large TCI set (e.g., one or more P-TCIs and / or one or more S-TCIs). At 1520, the Rx UE can be instructed to switch to an ACK / NACK-based HARQ process. At 1522, the Rx UE can be instructed to send an ACK or NACK based on the decoding result.

[0238] If the channel uncertainty is low at 1510, then at 1512, it may be indicated that the Rx UE uses a small TCI set (e.g., only (one or more) P-TCIs). At 1514, it may be indicated that the Rx UE switches to a HARQ process based on only NACK. At 1516, it may be indicated that the Rx UE sends NACK only when decoding fails.

[0239] Figure 16 An example method of sidelink UE-controlled TCI and HARQ feedback is shown. At 1602, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 1604, more than one TCI set may be utilized to activate the Rx UE for PSFCH transmission. The Tx UE may indicate the TCI set to the Rx UE for transmission on the PSFCH. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such a configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam. At 1606, the Tx UE may perform measurements and determine the channel uncertainty.

[0240] If the channel uncertainty is high at 1608, then at 1618, the Tx UE may determine to use a large TCI set (e.g., (one or more) P-TCIs and / or (one or more) S-TCIs). At 1620, the Tx UE may determine to switch to a HARQ process based on ACK / NACK. At 1622, it may be indicated that the Rx UE uses the large set TCI and ACK / NACK-based feedback. At 1624, the Rx UE may send an ACK or NACK based on the decoding result.

[0241] If the channel uncertainty is low at 1608, then at 1610, the Tx UE may determine to use a small TCI set (e.g., only (one or more) P-TCIs). At 1612, the Tx UE may determine to switch to a HARQ process based on only NACK. At 1614, it may be indicated that the Rx UE uses the small set TCI and only NACK feedback. At 1616, the Rx UE may send NACK only when decoding fails.

[0242] Figure 17 An example method of side link UE-controlled TCI and HARQ feedback is shown. At 1702, the UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 1704, the Rx UE is activated to transmit on the PSFCH for more than one TCI set. Alternatively, the UE may derive one or more TCIs for the PSFCH based on the configuration of the corresponding PSSCH. Examples of such a configuration may be the TCI of the corresponding PSSCH, the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. For example, in an embodiment, the Rx UE may derive one or more TCIs for PSFCH transmission based on the configuration received for the corresponding PSSCH. In an embodiment, such a configuration may be the frequency, code, time domain, and / or antenna / antenna port configuration of the corresponding PSSCH. In an embodiment, such a configuration may be one or more TCIs received for the corresponding PSSCH, and / or the associated RX beam of the Tx beam in the direction from the Tx UE to the RX beam. At 1706, the Rx UE may determine the channel uncertainty.

[0243] If it is determined at 1708 that the channel uncertainty is high, then at 1718, the Rx UE may determine to use a large TCI set (e.g., (one or more) P-TCI and / or (one or more) S-TCI). At 1720, the Rx UE may determine to switch to an ACK / NACK-based HARQ feedback scheme. At 1722, the Rx UE may notify the Tx UE that it has decided to use a large TCI set and ACK / NACK-based feedback.

[0244] If it is determined at 1708 that the channel uncertainty is low, then at 1710, the Rx UE may determine to use a small TCI set (e.g., only (one or more) P-TCI). At 1712, the Rx UE may determine to switch to a NACK-only-based HARQ feedback scheme. At 1714, the Rx UE may notify the Tx UE that it has decided to use a small TCI set and NACK-only-based feedback.

[0245] At 1716, the Tx UE may send an ACK to confirm the command from the Rx UE.

[0246] If the channel uncertainty is determined to be high, then at 1726, the Rx UE may send an ACK or NACK using the large TCI set based on the decoding result.

[0247] If the channel uncertainty is determined to be low, then at 1724, the Rx UE may send a NACK using the small TCI set only when decoding fails.

[0248] For PSFCH transmission, the Rx UE can be instructed which TCI to use for transmission on the PSFCH. The Tx UE can indicate the TCI availability status before PSFCH transmission. If the TCI availability status is "available", the PSFCH transmission can be sent on the TCI at the Rx UE. If the TCI availability status is "unavailable", the PSFCH transmission cannot be sent on the TCI at the Rx UE.

[0249] The beamwidth and BWP can be part of a process or scheme from which to select based on channel conditions and channel uncertainty. For example, if the channel uncertainty is high, a narrower beamwidth can be selected and used. Otherwise, if the channel uncertainty is low, a wider beamwidth can be selected and used. If the channel uncertainty is high, a BWP with fewer LBT failures can be selected, switched, and used. Otherwise, if the channel uncertainty is low, a new BWP can be selected and used. The same BWP can still be used.

[0250] Measurements for channel uncertainty can be performed at the Rx UE, Tx UE, or both. The channel uncertainty can be determined individually at the Rx UE, Tx UE, or jointly at both the Tx and Rx UEs. The Rx UE can assist the TCI and SL HARQ processes. Alternatively, the Tx UE or Rx UE can control the TCI and HARQ processes.

[0251] The SL HARQ feedback resource can be a frequency / time resource and can include a BWP. The BWP can also be dynamically selected and determined based on channel uncertainty in the shared spectrum to optimize performance.

[0252] The channel uncertainty can be determined based on the following: the number of LBT failures, the ratio of LBT failures to total measurements, the ratio of LBT failures to successes, the ratio of NACKs to ACKs, the percentage of NACKs, the channel busy ratio (CBR), the interference level, etc. or a combination.

[0253] The channel uncertainty measurement can be one of the following: the number of LBT failures, the ratio of LBT failures to total measurements, the ratio of LBT failures to successes, the ratio of NACKs to ACKs, the percentage of NACKs, the CBR, the interference level, etc.

[0254] Figure 18 An example method of TCI indication and feedback scheme indication is shown. At 1802, the UE can be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). At 1804, the UE can decode the SCI (e.g., the first and second stage SCI). At 1806, the UE can decode the PSSCH and obtain the SL MAC CE.

[0255] At 1808, the UE can determine whether the destination ID matches the decoded information. If the destination ID matches, then at 1810, the UE can further check the member ID.

[0256] If the member ID matches, then at 1814, the UE can determine the TCI set to be used (e.g., one or more P-TCIs and / or one or more S-TCIs) based on the TCI information. At 1816, the UE can determine the HARQ feedback scheme to be used based on the HARQ feedback indicator. At 1818, the UE can use the large TCI set to send ACK / NACK based on the decoding result, or use the small TCI set to send NACK in case of decoding failure.

[0257] If the member ID does not match, then at 1812, the UE can discard the information. Similarly, if the destination ID does not match, then at 1812, the UE can discard the information.

[0258] The destination ID can be the destination L1 ID or the destination L2 ID.

[0259] Figure 19 An example method of TCI indication and feedback scheme indication with an SL configurable control container is shown. At 1902, the UE can be configured or pre-configured with multiple TCI sets (e.g., P-TCIs and / or S-TCIs). At 1904, the UE can be configured or pre-configured with multiple HARQ feedback schemes. Such schemes can include ACK / NACK, NACK only, shared ACK / NACK, or a combination of these or other schemes. At 1906, the UE can decode the SCI (e.g., the first and second stage SCI). At 1908, the UE can decode the PSSCH and obtain the SL MAC CE.

[0260] If the destination ID matches at 1910, then at 1914, the UE can check the configuration of the SL control container.

[0261] If the SL MAC CE is configured as an SL control container and is used to carry the SL control information for TCI and the HARQ feedback scheme indicator at 1914, then at 1918, the UE can check the member ID in the SL MAC CE.

[0262] If the SCI is configured as an SL control container and is used to carry the SL control information for TCI and the HARQ feedback scheme indicator, then at 1916, the UE can check the member ID in the SCI.

[0263] If the member ID matches at 1920, at 1922, the UE may determine the set of TCIs to be used (e.g., one or more P-TCIs and / or one or more S-TCIs) based on the TCI information. At 1924, the UE may determine the HARQ feedback scheme to be used based on the HARQ feedback indicator.

[0264] If the member ID does not match, at 1912, the UE may discard the information. If the destination ID does not match, at 1912, the UE may discard the information.

[0265] The destination ID may be a destination L1 ID or a destination L2 ID.

[0266] In an embodiment, depending on the channel uncertainty, some UEs may use an ACK / NACK-based HARQ feedback scheme, and other UEs may use a NACK-only HARQ feedback scheme. The Tx UE may indicate the feedback scheme to the Rx UE via an SCI, an SL MAC CE, or a combination. For example, the Tx UE may use an SCI (e.g., a first-phase SCI and / or a second-phase SCI) to indicate the feedback scheme. The member ID may be used to identify the UE within the group. In the SCI-based method, one embodiment may be that in addition to the destination ID, the member ID may be included in the second-phase SCI. The Rx UE may receive the SCI and check the destination ID. If the destination ID matches, the UE may check the member ID. If the member ID matches, the HARQ feedback scheme may be selected or indicated in the second-phase SCI.

[0267] The association between the member ID and the HARQ feedback scheme may be in the following format: member ID 1, feedback scheme 1, member ID 2, feedback scheme 2, and so on. Such SL control information for the TCI and the HARQ feedback scheme may be included in the SCI and / or the SL MAC CE.

[0268] The association between the member ID and the SL TCI information may be in the following format: member ID 1, SL TCI information 1, member ID 2, SL TCI information 2, …. The association between the member ID and the SL TCI information may be in the following format: member ID 1, SL TCI set 1, member ID 2, SL TCI set 2, ….

[0269] The feedback scheme indicator may be included in the SCI, and the SL TCI information or set indication may be included in the SL MAC CE.

[0270] Alternatively, both the TCI information indication and the HARQ feedback scheme indication can be included or carried in the SCI. Both the SL TCI information indication and the HARQ feedback scheme indication can be included or carried in the SL MAC CE.

[0271] Table 1 shows an example of the SL HARQ feedback scheme indication. The SL HARQ feedback scheme indication can be carried in the SCI and / or the SL MAC CE.

[0272] Table 1

[0273] Member ID SL HARQ Feedback Scheme 1 Feedback Scheme x1 2 Feedback Scheme x2 3 Feedback Scheme x3 … …

[0274] Table 2 shows an example of the SL TCI information indication. The SL TCI information indication can be carried in the SCI and / or the SL MAC CE.

[0275] Table 2

[0276] Member ID SL TCI 1 TCI y1 2 TCI y2 3 TCI y3 … …

[0277] The SL HARQ feedback scheme indication can be carried in the SCI, and the SL TCI information indication can be carried in the SL MAC CE. The SL HARQ feedback scheme indication can be carried in the SL MAC CE, and the SL TCI information indication can be carried in the SCI.

[0278] Table 3 shows an example of the combined SL HARQ feedback scheme and the SL TCI information indication. The SL TCI information indication and the SL HARQ feedback scheme indication can be carried in the SCI or the SL MAC CE. Alternatively, both the SL TCI information indication and the SL HARQ feedback scheme indication can be jointly included or carried in the SL MAC CE, or both. The SL TCI information indication and the SL HARQ feedback scheme indication can be jointly included or carried in the SCI.

[0279] Table 3

[0280] Member ID SL HARQ Feedback Scheme SL TCI 1 Feedback Scheme x1 TCIy1 2 Feedback Scheme x2 TCIy2 3 Feedback Scheme x3 TCIy3 … … …

[0281] Table 4 shows an example of the SL HARQ feedback scheme indication. This embodiment can reduce the signaling overhead by associating member IDs under a single feedback scheme. Different from other solutions where each member ID can be associated with each feedback scheme, this requires more bits to indicate the HARQ feedback scheme. If multiple UEs use the same feedback scheme, the feedback scheme indication can be repeated. This embodiment removes the repeated indication of the HARQ feedback scheme, thus reducing the overhead.

[0282] Table 4

[0283]

[0284] Table 5 shows an example of SL TCI information indication. This embodiment can reduce signaling overhead by associating member IDs under the same (one or more) TCI. Different from other solutions where each member ID can be associated with each TCI, this requires more bits to indicate the (one or more) TCI. If multiple UEs use and share the same (one or more) TCI, the (one or more) TCI can be indicated repeatedly. This embodiment removes the repeated indication of TCI information, thus reducing the overhead.

[0285] Table 5

[0286]

[0287] The Rx UE and / or the Tx UE can receive the SL TCI information indication.

[0288] Although the use of multiple TCIs is described here with respect to a primary TCI and a secondary TCI as a means of characterizing multiple options for describing the relationship between different signals and / or channels (i.e., the relationship between a source signal / channel and a target signal / channel), the multiple TCIs for describing the relationship between a source signal / channel and a target signal / channel can be characterized in many ways, such as a primary TCI, a secondary TCI, a tertiary TCI,..., a k-th TCI, etc.

[0289] Hierarchical TCIs, where the TCIs are organized in a hierarchy, where a hierarchy is a superset of a subset of another hierarchy within the multiple TCIs. For example, in the case of a spatial domain relationship, multiple TCIs can be defined based on the granularity of the beam associated with the target signal / channel (e.g., beam width) and the granularity of the beam associated with the source signal / channel (e.g., beam width). For example, for the first level in the hierarchy, the beam associated with the target signal can be a first-width beam, and the beam associated with the source signal / channel can also be a first-width beam. For the second level in the hierarchy, the beam associated with the target signal can be a second-width beam, and the beam associated with the source signal / channel can also be a second-width beam, and so on. The first-width beam can mean a beam of the first width, the second-width beam can mean a beam of the second width, and so on.

[0290] A primary TCI, a secondary TCI, a tertiary TCI,..., a k-th TCI, etc. can be used. Alternatively, a first TCI, a second TCI, a third TCI,..., a k-th TCI, etc. can be used.

[0291] The terms primary TCI and secondary TCI, hierarchical TCI, or multiple TCIs including first TCI, second TCI, third TCI, k-th TCI, etc. may be used interchangeably with reference to the numbers of multiple TCIs corresponding to multiple options that can be configured or signaled to describe the relationship between a source signal / channel and a target signal / channel.

[0292] The primary TCI and secondary TCI signaling can also be based on two-stage PC5 RRC and SL MAC CE or three-stage PC5 RRC, SL MAC CE, and SCI. For example, in an embodiment, in two-stage PC5 RRC and SL MAC CE, the Rx UE can receive one or more TCIs via PC5 RRC signaling, and then the Rx UE can subsequently receive one or more TCIs via MAC CE, where the one or more TCIs received via MAC CE are a subset of the one or more TCIs received by the Rx UE via PC5 RRC signaling. In an embodiment and in combination with the three-stage PC5 RRC, SL MAC CE, and SCI method of TCI signaling, the Rx UE can receive one or more TCIs via PC5 RRC signaling, and then the Rx UE can receive one or more TCIs via MAC CE, where the one or more TCIs received via MAC CE are a subset of the one or more TCIs received by the Rx UE via PC5 RRC signaling. Additionally, the Rx UE can receive one or more TCIs via SCI, where the one or more TCIs received via SCI are a subset of the one or more TCIs received by the Rx UE via MAC CE or PC5 RRC signaling. In an embodiment, in two-stage PC5 RRC and SL MAC CE, the Tx UE can send one or more TCIs via PC5 RRC signaling, and then the Tx UE can send one or more TCIs via MAC CE, where the one or more TCIs sent via MAC CE are a subset of the one or more TCIs sent by the Tx UE via PC5 RRC signaling. In an embodiment of the three-stage PC5 RRC, SL MAC CE, and SCI method in combination with TCI signaling, the Tx UE can send one or more TCIs via PC5 RRC signaling, and then the Tx UE can send one or more TCIs via MAC CE, where the one or more TCIs sent via MAC CE are a subset of the one or more TCIs sent by the Tx UE via PC5 RRC signaling. Additionally, the Tx UE can send one or more TCIs via SCI, where the one or more TCIs sent via SCI are a subset of the one or more TCIs sent by the Tx UE via MAC CE or PC5 RRC signaling. The number of configured, activated, and / or indicated TCIs can be different between the primary TCI and the secondary TCI.

[0293] Sidelink TCI configuration in shared spectrum is disclosed.

[0294] The UE can learn one or more SL TCIs for first-stage SCI reception and second-stage SCI reception through one or more of the following methods.

[0295] One or more SL TCIs for the first - stage SCI and the second - stage SCI can be (pre -)configured in the UE.

[0296] The TCIs for the first - stage SCI and the second - stage SCI can be (pre -)configured separately in the UE. For example, in an embodiment, a first SL TCI is (pre -)configured in the UE for the first - stage SCI, and a second TCI is (pre -)configured in the UE for the second - stage SCI. The UE uses the first TCI to derive a suitable beam for receiving the first - stage SCI. Similarly, the UE uses the second TCI to derive a suitable beam for receiving the second - stage SCI.

[0297] One or more TCIs for the first - stage SCI and the second - stage SCI can be jointly (pre -)configured in the UE. For example, in an embodiment, a joint TCI is (pre -)configured in the UE, and the UE uses the joint TCI to derive a suitable beam for receiving the first - stage SCI and a suitable beam for receiving the second - stage SCI.

[0298] One or more SL TCIs for the first - stage SCI can be (pre -)configured in the UE, denoted herein as one or more first TCIs.

[0299] The UE can use the first TCI for the first - stage SCI to derive the second TCI for the second - stage SCI.

[0300] In an embodiment, the first TCI and the second TCI are separate TCIs. The UE uses the first TCI to derive a suitable beam for receiving the first - stage SCI. Similarly, the UE uses the second TCI to derive a suitable beam for receiving the second - stage SCI.

[0301] In an embodiment, the first TCI and the second TCI are joint TCIs. The UE uses the joint TCI to derive a suitable beam for receiving the first - stage SCI, as well as a suitable beam for receiving the second - stage SCI.

[0302] Similarly, with respect to the activation of one or more TCIs, one or more of the following methods can be considered.

[0303] One or more SL TCIs for the first - stage SCI and the second - stage SCI can be activated in the UE.

[0304] (One or more) TCIs for the first-stage SCI and the second-stage SCI can be activated separately in the UE. For example, in an embodiment, a first SL TCI is activated in the UE for the first-stage SCI, and a second TCI is activated in the UE for the second-stage SCI. The UE uses the first TCI to derive a suitable beam for reception for the first-stage SCI. Similarly, the UE uses the second TCI to derive a suitable beam for reception for the second-stage SCI.

[0305] (One or more) TCIs for the first-stage SCI and the second-stage SCI can be jointly activated in the UE. For example, in an embodiment, a joint TCI is activated in the UE, and the UE uses the joint TCI to derive a suitable beam for reception for the first-stage SCI and a suitable beam for reception for the second-stage SCI.

[0306] (One or more) SL TCIs for the first-stage SCI can be activated in the UE, denoted herein as (one or more) first TCIs.

[0307] The UE can use the first TCI for the first-stage SCI to derive the second TCI for the second-stage SCI.

[0308] In an embodiment, the first TCI and the second TCI are separate TCIs. The UE uses the first TCI to derive a suitable beam for reception for the first-stage SCI. Similarly, the UE uses the second TCI to derive a suitable beam for reception for the second-stage SCI.

[0309] In an embodiment, the first TCI and the second TCI are joint TCIs. The UE uses the joint TCI to derive a suitable beam for reception for the first-stage SCI, and a suitable beam for reception for the second-stage SCI.

[0310] The two-stage PC5RRC and SL MACCE or the three-stage PC5 RRC, SL MAC CE, and SCI, as signaling methods for the configuration and activation of TCIs in the UE described herein, are also applicable to the TCIs for the first-stage SCI and the second-stage SCI described herein.

[0311] In two-stage SL TCI indication, PC5 RRC can be used to configure a set of SL TCI states, and SL MAC CE can be used to indicate the exact (one or more) SL TCI states for the UE in the configured set of SL TCI states. In three-stage SL TCI indication, PC5 RRC can be used to configure SL TCI states, SL MAC CE can be used to activate a subset of SL TCI states in the configured set of SL TCI states, and SCI (e.g., stage-1 SCI, stage-2 SCI) can be used to indicate the exact (one or more) SL TCI states for the UE in the activated subset of SL TCI states. Two-stage and / or three-stage SL TCI indication can be used to indicate the (one or more) SL TCI states of an SL data channel (e.g., PSSCH), and such two-stage and / or three-stage SL TCI indication can also be used to indicate the (one or more) SL TCI states of an SL control channel (e.g., PSCCH). In addition, such two-stage and / or three-stage SL TCI indication can also be used for same-carrier scheduling or cross-carrier scheduling. In addition, such two-stage and / or three-stage SL TCI indication can also be used for same-slot scheduling or cross-slot scheduling.

[0312] Other design embodiments for sidelink TCI are disclosed.

[0313] Hereinafter, the term SL TCI state or simply TCI state can be used as a configuration element or information element (e.g., SL TCI-State or SL TCI-State-r18, SL TCI-State-r19 or SL TCI-State-r20, etc.), including one or more RSs, corresponding (one or more) QCL types, etc. One or more TCIs can be determined or derived from the TCI state. For example, a TCI in the transmission direction from UE1 to UE2 or in the transmission direction from UE2 to UE1 can be determined from the TCI state.

[0314] The term SL TCI code point can be used herein as an allowed value of the SL TCI field in DCI or SCI. The SL TCI code point can be mapped to one or more SL TCI states (e.g., multiple SL TCI states for the TCI in the transmission direction from UE1 to UE2 or for the TCI in the transmission direction from UE2 to UE, or one SL TCI state for the TCI in the transmission direction from UE1 to UE2 and one TCI state for the TCI in the transmission direction from UE2 to UE1). The SL TCI code point can be mapped to one or more TCIs (e.g., one TCI for the transmission direction from UE1 to UE2 and one TCI for the transmission direction from UE2 to UE1). The TCI state can correspond to one or more TCIs.

[0315] The TCI for the UE2-to-UE1 transmission direction and the TCI for the UE1-to-UE2 transmission direction can both be derived from the same TCI state. For example, UE2 can use the same SL RS to determine the UE2 Rx beam or the UE1 Tx beam for the UE1-to-UE2 transmission direction, and to determine the UE2 Tx beam for the UE2-to-UE1 transmission direction. In this case, a joint pool (set) of TCI states can be configured for both the UE1-to-UE2 transmission direction and the UE2-to-UE1 transmission direction.

[0316] Similarly, separate pools (sets) of TCI states can be configured (i.e., one pool of TCI states for the UE1-to-UE2 transmission direction and another pool of TCI states for the UE2-to-UE1 transmission direction). For example, a first SL RS can be used to determine the UE2 Rx beam or the UE1 Tx beam for the UE1-to-UE2 transmission direction, while a second SL RS can be used to determine the U2 Tx beam for the UE2-to-UE1 transmission direction.

[0317] The SL TCI configuration granularity is disclosed.

[0318] The TCI can be configured in the Rx UE or the Tx UE at the following granularity levels: per component carrier (CC); per bandwidth part (BWP); per control resource set (CORESET); per reference signal (RS) type; per Rx UE (e.g., from the perspective of the Tx UE); per Tx UE (e.g., from the perspective of the Rx UE); per pair of Tx and Rx UEs; per sidelink link ID; per service or per destination L2 ID; per pair of source L2 ID and destination L2 ID; per source L2 ID; per RS type; per channel (e.g., PSBCH, PSCCH, PSSCH, PSFCH); per resource pool; source and target RS types and physical channels.

[0319] The source or target RS type can be one or more of the following: SLSS (S-SSB); SL CSI-RS; SL PT-RS; DMRS for PSCCH or DMRS for PSSCH;

[0320] The source channel or target channel can be one or more of the following: physical sidelink broadcast channel (PSBCH); physical sidelink control channel (PSCCH); physical sidelink shared channel (PSSCH); physical sidelink feedback channel (PSFCH).

[0321] The following QCL types can be considered on the sidelink: 'QCL-TypeA': {Doppler shift, Doppler spread, average delay, delay spread}; 'QCL-TypeB': {Doppler shift, Doppler spread}; 'QCL-TypeC': {Doppler shift, average delay}; 'QCL-TypeD': {spatial Rx parameter}. (One or more) QCL types other than "QCL-TypeA", "QCL-TypeB", "QCL-TypeC", and "QCL-TypeD" can also be considered, and this is not restricted.

[0322] One or more of the following nodes can send a source RS: The Tx UE (or an assistant or secondary node of the Tx UE) can send a source RS to the Rx UE with or without assistance from the Rx UE (or an assistant or secondary node of the Tx UE); The Rx UE (or an assistant or secondary node of the Rx UE) can send a source RS to the Tx UE with or without assistance from the TX UE (or an assistant or secondary node of the Rx UE) (e.g., to support HARQ feedback on the PSFCH).

[0323] One or more of the following nodes may configure, activate, or perform both the configuration and activation of TCI configuration: The serving cell of the Tx UE or the control node may configure TCI information in the Tx UE with or without assistance information from the Rx UE or the serving cell of the Rx UE; The serving cell of the Tx UE or the control node may activate the (pre)-configured TCI information in the Tx UE with or without assistance information from the Rx UE or the serving cell of the Rx UE; The serving cell of the Rx UE or the control node may configure TCI information in the Rx UE with or without assistance information from the Tx UE or the serving cell of the Tx UE; The serving cell of the Rx UE or the control node may activate the (pre)-configured TCI information in the Rx UE with or without assistance information from the Tx UE or the serving cell of the Tx UE; The Tx UE (or an assistant or auxiliary node of the Tx UE) may configure TCI information into the Rx UE with or without assistance information from the RX UE or the serving cell of the RX UE; The Tx UE (or an assistant or auxiliary node of the Tx UE) may activate the (pre)-configured TCI information in the Rx UE with or without assistance information from the RX UE or the serving cell of the RX UE; The Rx UE (or an assistant or auxiliary node of the Rx UE) may configure TCI information in the Tx UE with or without assistance information from the Rx UE or the serving cell of the Rx UE; The Rx UE (or an assistant or auxiliary node of the Rx UE) may configure the (pre)-configured TCI information in the Tx UE with or without assistance information from the Rx UE or the serving cell of the Rx UE.

[0324] The methods and solutions described herein may be applied to the reception of sidelink data channels, sidelink control channels, sidelink reference signals, other signals or channels, etc. The methods and solutions described herein may be applied to the transmission of sidelink data channels, sidelink control channels, sidelink feedback channels, sidelink reference signals, other signals or channels, etc. The methods and solutions described herein may be applied to different broadcast types, such as unicast, multicast, broadcast, etc. The methods and solutions described herein may be applied to unlicensed spectrum, shared spectrum, licensed spectrum, etc. The methods and solutions described herein may be applied to the reception and / or transmission of single-stage, two-stage or multi-stage communication, e.g., the reception and / or transmission of a two-stage sidelink control channel (e.g., a first-stage SCI and a second-stage SCI).

[0325] In an embodiment, the UE may perform sidelink TCI-based HARQ feedback with hybrid TCI and HARQ feedback.

[0326] The UE may be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). The UE may be configured or pre-configured with multiple HARQ feedback schemes (e.g., ACK / NACK, NACK only, etc.).

[0327] The UE may be instructed to send a PSFCH transmission with (one or more) TCI(s).

[0328] If the channel uncertainty is greater than a first threshold, the UE may be instructed to use a large TCI set (e.g., (one or more) P-TCI and / or (one or more) S-TCI).

[0329] If the channel uncertainty is greater than a second threshold, the UE may switch to a HARQ feedback scheme based on individual ACK / NACK.

[0330] The UE may be instructed to send an individual ACK or NACK based on the decoding result.

[0331] If the channel uncertainty is not greater than the second threshold, the UE may switch to a NACK-only HARQ feedback scheme.

[0332] The UE may be instructed to send a NACK only when decoding fails.

[0333] If the channel uncertainty is greater than the first threshold, the UE may be instructed to use a small TCI set (e.g., only (one or more) P-TCI).

[0334] If the channel uncertainty is greater than a third threshold, the UE may switch to a HARQ feedback scheme based on individual ACK / NACK.

[0335] The UE may be instructed to send an individual ACK or NACK based on the decoding result.

[0336] If the channel uncertainty is not greater than the first threshold, the UE may switch to a NACK-only based HARQ feedback scheme.

[0337] The UE may be instructed to send a NACK only when decoding fails.

[0338] The channel uncertainty may be determined based on one or more of the following: the number of LBT failures, the ratio of LBT failures to total measurements, the ratio of LBT failures to successes, the ratio of NACKs to ACKs, the percentage of NACKs, the channel busy ratio (CBR), the interference level, etc. or a combination thereof.

[0339] In an embodiment, the UE may perform sidelink TCI-based HARQ feedback with configurable SL control.

[0340] The UE can be configured or pre-configured with multiple TCI sets (e.g., P-TCI and / or S-TCI). The UE can decode the SCI (e.g., the first and second stage SCI). The UE can decode the PSSCH and obtain the SL MAC CE.

[0341] If the destination ID matches, the UE can check the configuration of the SL control container.

[0342] If the SL MAC CE is configured as an SL control container and is used to carry SL control information for TCI and a HARQ feedback scheme indicator, the UE can check the member ID in the SL MAC CE.

[0343] If the SCI is configured as an SL control container and is used to carry SL control information for TCI and a HARQ feedback scheme indicator, the UE can check the member ID in the SCI.

[0344] If the member IDs match, then the UE can determine the TCI set to be used (e.g., one or more P-TCIs and / or one or more S-TCIs) based on the TCI information. The UE can determine the HARQ feedback scheme to be used based on the HARQ feedback indicator.

[0345] If the member IDs do not match, the UE can discard the information. If the destination ID does not match, the UE can discard the information.

[0346] The destination ID can be a destination L1 ID or a destination L2 ID.

[0347] In some aspects, the present disclosure relates to a method implemented by a wireless transmit / receive unit (WTRU). The method includes receiving information indicating multiple side link (SL) transmission configuration indicators (TCI), where the SL TCI includes at least an SL primary TCI (P-TCI) and an SL secondary TCI (S-TCI). The method also includes receiving information indicating multiple hybrid automatic repeat request (HARQ) configurations. The method also includes determining channel uncertainty. The method also includes determining a combination of an SL TCI set and a HARQ configuration for communication via a side link feedback channel based on a comparison of the channel uncertainty with at least one threshold, where the determined SL TCI set is a first SL TCI set or a second SL TCI set, and where the first SL TCI set is less than the second SL TCI set. The method also includes transmitting a transmission via the side link feedback channel using the determined SL TCI set and using the determined HARQ configuration.

[0348] In some embodiments, the first SL TCI set includes only the SL P-TCI. In some embodiments, the second SL TCI includes at least the SL P-TCI and the SL S-TCI.

[0349] In some embodiments, the HARQ configuration includes a separate ACK / NACK, a shared ACK / NACK, or only NACK.

[0350] In some embodiments, the channel uncertainty is based on the number of listen-before-talk (LBT) failures, the LBT failure rate, the ratio of NACK to ACK, the ratio of ACK to NACK, the percentage of NACK, the percentage of ACK, the channel busy ratio (CBR), or the interference level, or a combination of any of these.

[0351] In some embodiments, under the condition that the channel uncertainty is less than a first threshold, it is determined to use the first SL TCI set and the only NACK HARQ configuration. In some embodiments, under the condition that the channel uncertainty is greater than the first threshold and less than a second threshold, it is determined to use the second SL TCI set and the only NACK HARQ configuration. In some embodiments, under the condition that the channel uncertainty is greater than the first threshold and greater than the second threshold and less than a third threshold, it is determined to use the second SL TCI set and the shared ACK / NACK HARQ configuration. In some embodiments, under the condition that the channel uncertainty is greater than the first threshold and greater than the second threshold and greater than the third threshold, it is determined to use the second SL TCI set and the separate ACK / NACK HARQ configuration.

[0352] In some embodiments, the first threshold is less than the second threshold, and the second threshold is less than the third threshold, where the first threshold indicates low channel uncertainty and the third threshold indicates high channel uncertainty.

[0353] In some embodiments, the sidelink feedback channel is a physical sidelink feedback channel (PSFCH).

[0354] In some embodiments, the method includes transmitting an identifier of the determined channel uncertainty via the sidelink feedback channel. In some embodiments, the method includes transmitting an identifier of the determined HARQ configuration via the sidelink feedback channel.

[0355] In another aspect, the present disclosure relates to a wireless transmit / receive unit (WTRU) comprising: one or more transceivers; one or more memory devices; and one or more processors. The one or more memory devices may be configured to store information indicating a plurality of sidelink (SL) transmission configuration indications and information indicating a plurality of hybrid automatic repeat request (HARQ) configurations, wherein the SL TCI includes at least an SL primary TCI (P-TCI) and an SL secondary TCI (S-TCI). The one or more processors may be configured to: determine channel uncertainty; based on a comparison of the channel uncertainty with at least one threshold, determine a combination of an SL TCI set and an HARQ configuration for communication via a sidelink feedback channel, wherein the determined SL TCI set is a first SL TCI set or a second SL TCI set, wherein the first SL TCI set is smaller than the second SL TCI set; and use the one or more transceivers to transmit a transmission via the sidelink feedback channel using the determined SL TCI set and the determined HARQ configuration.

[0356] In some embodiments, the channel uncertainty is based on the number of listen-before-talk (LBT) failures, the LBT failure rate, the NACK to ACK ratio, the ACK to NACK ratio, the percentage of NACKs, the percentage of ACKs, the channel busy ratio (CBR), or the interference level, or a combination of any of these.

[0357] In some embodiments, under the condition that the channel uncertainty is less than a first threshold, it is determined to use the first SL TCI set and only the NACK HARQ configuration. In some embodiments, under the condition that the channel uncertainty is greater than the first threshold and less than a second threshold, it is determined to use the second SL TCI set and only the NACK HARQ configuration. In some embodiments, under the condition that the channel uncertainty is greater than the first threshold and greater than the second threshold and less than a third threshold, it is determined to use the second SL TCI set and a shared ACK / NACK HARQ configuration. In some embodiments, under the condition that the channel uncertainty is greater than the first threshold and greater than the second threshold and greater than the third threshold, it is determined to use the second SL TCI set and a separate ACK / NACK HARQ configuration.

[0358] In some embodiments, the one or more processors are further configured to: use the one or more transceivers to transmit an indication of the determined channel uncertainty or an indication of the determined HARQ configuration.

[0359] Although the features and elements have been described above in particular combinations, one of ordinary skill in the art will understand that each feature or element can be used separately or in any combination with other features and elements. In addition, the methods described herein can be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or a processor. Examples of computer-readable media include electronic signals (sent via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, buffer memories, semiconductor storage devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks. A processor associated with the software can be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: Receiving information indicating a plurality of sidelink (SL) transmission configuration indicators (TCIs), wherein the SL TCI includes at least an SL primary TCI (P-TCI) and an SL secondary TCI (S-TCI); Receiving information indicating a plurality of hybrid automatic repeat request (HARQ) configurations; Determining channel uncertainty; Based on a comparison of the channel uncertainty with at least one threshold, determining a combination of an SL TCI set and an HARQ configuration for communication via a sidelink feedback channel, wherein the determined SL TCI set is a first SL TCI set or a second SL TCI set, wherein the first SL TCI set is smaller than the second SL TCI set; and Transmitting a transmission via the sidelink feedback channel using the determined SL TCI set and using the determined HARQ configuration.

2. The method according to claim 1, wherein, The first SL TCI set includes only the SL P-TCI.

3. The method according to claim 1 or 2, wherein The second SL TCI includes at least the SL P-TCI and the SL S-TCI.

4. The method according to any one of claims 1 to 3, wherein The HARQ configuration includes individual ACK / NACK, shared ACK / NACK, or NACK only.

5. The method according to any one of claims 1 to 4, wherein The channel uncertainty is at least partially based on the number of listen-before-talk (LBT) failures, the LBT failure rate, the ratio of NACK to ACK, the ratio of ACK to NACK, the percentage of NACK, the percentage of ACK, the channel busy ratio (CBR), or the interference level.

6. The method according to any one of claims 1 to 5, wherein Under the condition that the channel uncertainty is less than a first threshold, the determination is to use the first SL TCI set and the NACK-only HARQ configuration.

7. The method according to any one of claims 1 to 6, wherein Under the condition that the channel uncertainty is greater than the first threshold and less than a second threshold, the determination is to use the second SL TCI set and the NACK-only HARQ configuration.

8. The method according to any one of claims 1 to 7, wherein Under the condition that the channel uncertainty is greater than the first threshold, greater than the second threshold, and less than a third threshold, the determination is to use the second SL TCI set and the shared ACK / NACK HARQ configuration.

9. The method according to any one of claims 1 to 8, wherein Under the condition that the channel uncertainty is greater than the first threshold, greater than the second threshold, and greater than the third threshold, the determination is to use the second SL TCI set and the individual ACK / NACK HARQ configuration.

10. The method according to any one of claims 1 to 9, wherein, The first threshold is less than the second threshold, and the second threshold is less than the third threshold, wherein the first threshold indicates low channel uncertainty, and the third threshold indicates high channel uncertainty.

11. The method according to any one of claims 1 to 10, wherein, The sidelink feedback channel is a physical sidelink feedback channel (PSFCH).

12. The method according to any one of claims 1 to 11, further comprising: Transmitting an identification of the determined channel uncertainty via the sidelink feedback channel.

13. The method according to any one of claims 1 to 12, further comprising: Transmitting an identification of the determined HARQ configuration via the sidelink feedback channel.

14. A wireless transmit / receive unit (WTRU) comprising: One or more transceivers; One or more memory devices that store: Information indicating multiple sidelink (SL) transmission configuration indicators (TCIs), wherein the SL TCIs include at least an SL primary TCI (P-TCI) and an SL secondary TCI (S-TCI); and Information indicating multiple hybrid automatic repeat request (HARQ) configurations; And One or more processors configured to: Determine channel uncertainty, Based on a comparison of the channel uncertainty with at least one threshold, determine a combination of an SL TCI set and an HARQ configuration for communication via a sidelink feedback channel, wherein the determined SL TCI set is a first SL TCI set or a second SL TCI set, and wherein the first SL TCI set is less than the second SL TCI set; Use the determined SL TCI set and use the determined HARQ configuration to transmit a transmission via the sidelink feedback channel using the one or more transceivers.

15. The WTRU according to claim 14, wherein the channel uncertainty is at least partially based on a listen-before-talk (LBT) failure count, an LBT failure rate, a ratio of NACK to ACK, a ratio of ACK to NACK, a percentage of NACK, a percentage of ACK, a channel busy ratio (CBR), or an interference level.

16. The WTRU according to claim 14 or 15, wherein under the condition that the channel uncertainty is less than a first threshold, the determination is to use the first SL TCI set and only a NACK HARQ configuration.

17. The WTRU according to any one of claims 14 to 16, wherein under the condition that the channel uncertainty is greater than the first threshold and less than a second threshold, the determination is to use the second SL TCI set and only a NACK HARQ configuration.

18. The WTRU according to any one of claims 14 to 17, wherein under the condition that the channel uncertainty is greater than the first threshold and greater than the second threshold and less than a third threshold, the determination is to use the second SL TCI set and a shared ACK / NACK HARQ configuration.

19. The WTRU according to any one of claims 14 to 18, wherein under the condition that the channel uncertainty is greater than the first threshold and greater than the second threshold and greater than the third threshold, the determination is to use the second SL TCI set and a separate ACK / NACK HARQ configuration.

20. The WTRU according to any one of claims 14 to 19, wherein the one or more processors are further configured to use the one or more transceivers to transmit an identification of the determined channel uncertainty or an identification of the determined HARQ configuration.

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