Method and apparatus for flexible aperiodic SRS transmission

Abstract

SUMMARY OF THE INVENTION [0005] A method, apparatus, and system for flexible aperiodic reference signal (RS) transmission is provided. For example, the method, implemented in a wireless transmit / receive unit (WTRU) for wireless communication, includes receiving configuration information of one or more sounding reference signal (SRS) resource sets, where each SRS resource set of the one or more SRS resource sets is associated with a set of slot offsets and slot offset deltas, receiving downlink control information (DCI) indicating an SRS request indicating an SRS resource set among the one or more SRS resource sets, determining an SRS configuration from a set of SRS configurations for SRS transmission, determining a slot for transmitting the SRS based on the determined SRS configuration, and transmitting the SRS in the determined slot using resources of the indicated SRS resource set.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 049,932, filed on July 9, 2020, U.S. Provisional Patent Application No. 63 / 091,597, filed on October 14, 2020, and U.S. Provisional Patent Application No. 63 / 169,974, filed on April 2, 2021, with the United States Patent and Trademark Office, the entire contents of each of which are hereby incorporated by reference herein as if fully set forth below in their entirety and for all applicable purposes.

Summary of the Invention

[0002] Embodiments disclosed herein generally relate to wireless and / or wired communication networks. For example, one or more embodiments disclosed herein relate to methods and apparatuses for flexible aperiodic sounding reference signal (SRS) transmission.

[0003] In one embodiment, a method implemented in a wireless transmit / receive unit (WTRU) for wireless communication includes receiving configuration information of one or more sounding reference signal (SRS) resource sets, wherein each SRS resource set of the one or more SRS resource sets is associated with a set of slot offset and slot offset delta; receiving downlink control information (DCI) indicating an SRS request indicating an SRS resource set among the one or more SRS resource sets; determining an SRS configuration from a set of SRS configurations for SRS transmission; determining a slot for transmitting the SRS based on the determined SRS configuration; and transmitting the SRS using the resources of the indicated SRS resource set in the determined slot.

Brief Description of the Drawings

[0004] A more detailed understanding can be obtained from the following detailed description given by way of example in conjunction with the drawings attached hereto. The diagrams of such drawings, like the detailed description, are examples. Therefore, the drawings and the detailed description should not be regarded as limiting, and other equally effective examples are possible and likely. Also, like reference numerals in the figures indicate like elements.

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[0005] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of these specific details. In other instances, well - known methods, procedures, components, and circuits have not been described in detail so as not to obscure the following description. Further, embodiments and examples not specifically described herein may be practiced in lieu of or in combination with the embodiments and other examples explicitly, implicitly, and / or inherently (collectively “provided”) described, disclosed, or otherwise provided herein. In this specification, various embodiments are described and / or claimed in which an apparatus, system, device, etc. and / or any of their elements perform various operations, processes, algorithms, functions, etc. and / or any part thereof, but it should be understood that any embodiment described and / or claimed herein assumes that any apparatus, system, device, etc. and / or any of their elements are configured to perform any operation, process, algorithm, function, etc. and / or any part thereof.

[0006] Communication Networks and Devices The methods, apparatuses, and systems provided herein are well-suited for communications involving both wired and wireless networks. Wired networks are well-known. An overview of various types of wireless devices and infrastructure is provided with respect to FIGS. 1A-1D, and the various elements of the network can be utilized, executed, arranged, and / or adapted and / or configured for the methods, apparatuses, and systems provided herein.

[0007] FIG. 1A 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 multiple 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 a plurality of wireless users to access the content as described above through sharing of system resources including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), etc.

[0008] As shown in Figure 1A, the communication system 100 can include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to interchangeably as a "station" and / or "STA", can be configured to transmit and / or receive wireless signals and can be a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscriber-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., telesurgery), an industrial device and application (e.g., a robot and / or other wireless device operating in an industrial and / or automated processing chain context), a home appliance device, a device operating in a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d can be referred to interchangeably as a UE.

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

[0010] Base station 114a can be part of RAN 104 / 113 and can also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. Base station 114a and / or base station 114b can be configured to transmit and / or receive radio signals at one or more carrier frequencies, which can be referred to as a cell (not shown). These frequencies can be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. The cell can provide wireless service coverage to a specific geographic area that can be relatively fixed or can change over time. The cell can be further divided into cell sectors. For example, the cell associated with base station 114a can be divided into three sectors. Thus, in one embodiment, base station 114a can include three transceivers, for example, one transceiver for each sector of the cell. In one embodiment, base station 114a can use multiple-input multiple-output (MIMO) technology and can utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

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

[0012] More specifically, as described above, the communication system 100 can be a multiple access system and can employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a within RAN 104 / 113, and the WTRUs 102a, 102b, 102c can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish the air interfaces 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed Downlink Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0013] In one 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 establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

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

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

[0016] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement wireless technologies such as IEEE 802.11 (e.g., Wireless Fidelity (WiFi)), IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0017] The base station 114b in FIG. 1A can be, for example, a wireless router, a home Node B, a home eNodeB, or an access point, and can utilize any suitable RAT to facilitate wireless connection in a local area, such as an office, a home, a vehicle, a campus, an industrial facility, an aerial corridor (for use by, for example, drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d can implement a wireless technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d can implement a wireless technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell or a femto cell. As shown in FIG. 1A, the base station 114b can have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

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

[0019] CN106 / 115 may also function as a gateway for WTRU102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a public switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices, where these networks and devices use a common communication protocol such as the transmission control protocol (TCP), the user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs that may employ the same or a different RAT as the RAN 104 / 113.

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

[0021] Figure 1B is a system diagram showing an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 can include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripheral devices 138. It will be understood that the WTRU 102 can include any partial combination of the foregoing elements while remaining consistent with one embodiment.

[0022] The processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120 that can be coupled to a transmit / receive element 122. Although Figure 1B shows the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

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

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

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

[0026] The processor 118 of the WTRU 102 may be coupled to the speaker / microphone 124, keypad 126, and / or display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit) and may receive user input data therefrom. The processor 118 may also output user data to the speaker / microphone 124, keypad 126, and / or display / touchpad 128. Further, the processor 118 may access information from and store data in any suitable type of memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

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

[0028] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the location of the WTRU 102. In addition to or instead of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via the air interface 116 and / or may determine its location based on the timing of signals received from two or more nearby base stations. It will be understood that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with one embodiment.

[0029] The processor 118 may also be further coupled to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connections. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral devices 138 may include one or more sensors, which 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, and / or a humidity sensor.

[0030] WTRU102 may include a full-duplex radio in which transmission and reception of some or all of the signals (e.g., associated with certain subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) can be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via either hardware (e.g., a choke) or signal processing (e.g., via a separate processor (not shown) or processor 118) via a processor. In one embodiment, WRTU102 may include a half-duplex radio for transmission and reception of some or any of all of the signals (e.g., associated with a particular subframe for either UL (e.g., for transmission) or downlink (e.g., for reception)).

[0031] FIG. 1C is a system diagram showing RAN104 and CN106 according to one embodiment. As described above, RAN104 can communicate with WTRU102a, 102b, 102c via air interface 116 using E-UTRA radio technology. RAN104 can also communicate with CN106.

[0032] RAN104 may include eNode-Bs 160a, 160b, 160c, but it will be understood that RAN104 may include any number of eNode-Bs while remaining consistent with one embodiment. Each of eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with WTRU102a, 102b, 102c via air interface 116. In one embodiment, eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, eNode-B 160a may transmit and / or receive radio signals from / to WTRU102a, for example, using multiple antennas.

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

[0034] CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is shown as part of CN 106, it will be understood that any of these elements may be owned and / or operated by entities other than the CN operator.

[0035] MME 162 can be connected to each of eNode-Bs 160a, 160b, and 160c in RAN 104 via the S1 interface and can function as a control node. For example, MME 162 can play roles such as authenticating users of WTRUs 102a, 102b, 102c, activating / deactivating bearers, and selecting a gateway in a specific service during the initial attach of WTRUs 102a, 102b, 102c. MME 162 can provide control plane functions for switching between RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and / or WCDMA.

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

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

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

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

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

[0041] A WLAN in infrastructure basic service set (BSS) mode can have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP can have access or an interface to another type of wired / wireless network that carries traffic entering and / or exiting the distribution system (DS) or BSS. Traffic originating from outside the BSS and destined for an STA can reach the STA through the AP and be delivered to the STA. Traffic originating from an STA and destined for a destination outside the BSS can be sent to the AP and then sent to their respective destinations. Traffic between STAs within the BSS can be transmitted, for example, via the AP. The source STA can send the traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be regarded as and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be transmitted in a direct link setup (DLS) between the source STA and the destination STA (e.g., directly between them). In certain representative embodiments, the DLS can use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all of the STAs) can communicate directly with each other. The IBSS mode of communication can be referred to herein as the "ad hoc" communication mode.

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

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

[0044] A Very High Throughput (VHT) STA may support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. The above-mentioned 40 MHz and / or 80 MHz wide channels may be formed by combining consecutive 20 MHz channels. A 160 MHz channel may be formed by combining eight consecutive 20 MHz channels, or by combining two non-consecutive 80 MHz channels, which may be referred to as an 80+80 configuration. In the case of the 80+80 configuration, after channel coding, the data may pass through a segment parser that may split the data into two streams. The Inverse Fast Fourier Transform (IFFT) process and time domain processing may be performed separately for each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed, and the combined data may be transmitted to the Medium Access Control (MAC).

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

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

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

[0048] FIG. 1D is a system diagram showing RAN 113 and CN 115 according to one embodiment. As described above, RAN 113 can communicate with WTRUs 102a, 102b, 102c via air interface 116 using NR radio technology. RAN 113 can also communicate with CN 115.

[0049] RAN 113 may include gNBs 180a, 180b, and 180c, but it should be understood that RAN 113 may include any number of gNBs while remaining consistent with one embodiment. Each of gNBs 180a, 180b, and 180c may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 108b may use beamforming to transmit and / or receive signals to / from gNBs 180a, 180b, and 180c. Thus, gNB 180a may transmit a wireless signal to WTRU 102a and / or receive a wireless signal from WTRU 102a, for example, using multiple antennas. In one embodiment, gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, and the remaining component carriers may be on licensed spectrum. In one embodiment, gNBs 180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may receive coordinated transmission from gNB 180a and gNB 180b (and / or gNB 180c).

[0050] WTRUs 102a, 102b, and 102c may communicate with gNBs 180a, 180b, and 180c using transmissions associated with scalable numerology. For example, the OFDM symbol interval and / or the OFDM subcarrier interval may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. WTRUs 102a, 102b, and 102c may communicate with gNBs 180a, 180b, and 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., including various numbers of OFDM symbols and / or having absolute times of various lengths).

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

[0052] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to user plane functions (UPFs) 184a, 184b, routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, gNBs 180a, 180b, and 180c can communicate with each other via the Xn interface.

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

[0054] AMF 182a and 182b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can function as control nodes. For example, AMF 182a and 182b can play roles such as user authentication of WTRUs 102a, 102b, and 102c, support for network slicing (e.g., handling different PDU sessions with different requirements), selection of specific SMFs 183a and 183b, management of registration areas, termination of NAS signaling, and mobility management. Network slices can be used by AMF 182a and 182b to customize the CN support for WTRUs 102a, 102b, and 102c based on the type of services being utilized by WTRUs 102a, 102b, and 102c. For example, different network slices can be established for different use cases such as services that rely on ultra-reliable low latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. AMF 182 can provide control plane functions for switching between RAN 113 and other RANs (not shown) that employ other radio technologies such as non-3GPP access technologies like LTE, LTE-A, LTE-A Pro, and / or WiFi.

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

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

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

[0058] In view of FIGS. 1A-1D and the corresponding descriptions thereof, one or more of the functions described herein with respect to one or more of WTRU102a-d, base stations 114a-b, eNode-Bs 160a-c, MME162, SGW164, PGW166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functionality.

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

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

[0061] Sounding reference signal (SRS) transmission The sounding reference signal (SRS) is mainly used for uplink channel measurements. SRS transmission can also be used to assist in downlink channel state information (CSI) estimation for partial or full inter-channel. Moreover, SRS can be used for beam management, where SRS transmission through different SRS resources supports beam selection by the network (e.g., gNB). Therefore, enabling dynamic and flexible sounding procedures with appropriate capacity and coverage is essential for MIMO systems (e.g., to improve MIMO performance).

[0062] In 5G New Radio (NR) (e.g., NR Release 16), a WTRU (e.g., UE) may be configured with one or more SRS resource sets (e.g., SRS-ResourceSet) containing up to K SRS resources, where K is based on the WTRU (e.g., UE) capabilities. The SRS resource set can be configured for different applications (e.g., usage), such as beamManagement, codebook, nonCodebook, or antennaSwitching. In some examples, the time-domain behavior of the SRS resource configuration is indicated by the higher-layer parameter resourceType. The time-domain behavior can be configured as periodic, semi-persistent, and / or aperiodic. In NR (e.g., NR Release 16), a WTRU cannot have different time-domain behaviors (e.g., periodic and semi-persistent), and in some cases, a WTRU cannot have different periodicities for SRS resources within the same SRS resource set.

[0063] In some examples, when the WTRU is triggered to transmit SRS on the same symbol, the aperiodic SRS has a higher transmission priority than the periodic SRS and / or the semi-persistent SRS. In some cases, the aperiodic SRS has a higher priority than the physical uplink control channel (PUCCH), except when the PUCCH is carrying a hybrid automatic repeat request (HARQ) (e.g., HARQ-ACK or NACK), a link recovery request, and / or a scheduling request (SR), and when the aperiodic SRS is triggered to be transmitted on the same symbol that is also used for the PUCCH.

[0064] In semi-persistent SRS operation, the WTRU may be activated / deactivated by downlink control information (DCI) to start / stop SRS transmission. However, the impact from misdetection of the deactivation signal can be significant because the WTRU may continue to transmit SRS, which can result in unnecessary interference and WTRU battery consumption.

[0065] Figure 2 shows an exemplary operation of aperiodic SRS transmission. In the case of an aperiodic SRS configuration, a WTRU (e.g., a UE) can receive a set of upper layer parameters for an SRS-ResourceSet, including, for example, slotOffset, srs-ResourceSetId, AperiodicSRS-ResourceTrigger, and / or AperiodicSRS-ResourceTriggerList. The aperiodic SRS transmission can be triggered by WTRU-specific DCI, group-common DCI, or uplink DCI. The associated SRS request field (e.g., a 2-bit SRS request field) in DCI format 0_1, format 1_1, format 0_2 (when an SRS request field is present), and format 1_2 (when an SRS request field is present) can trigger the corresponding SRS transmission.

[0066] When a WTRU receives DCI that triggers an aperiodic SRS in slot n based on the 3GPP specifications (e.g., 3GPP TS 38.214, Release 16), the WTRU transmits an aperiodic SRS in each of the SRS resource sets triggered in the following slots.

[0067]

Number

[0068] In some current implementations, when a WTRU receives DCI that triggers an aperiodic SRS, the slot level offset for sending the aperiodic SRS depends on slotOffset, which is an upper layer parameter configured by radio resource control (RRC) signaling. Depending on the RRC configuration value for the determination of the transmission slot for the aperiodic SRS imposes certain limitations on the performance of the wireless communication system. For example, if the indicated slot offset occurs within a downlink (DL) slot, the intended SRS transmission is ignored and the scheduler needs to retry for another opportunity. In another example, in a multi-user MIMO (MU-MIMO) system, some users can be triggered to ride on a simultaneous aperiodic SRS transmission to provide an accurate estimation of the channel and interference for the scheduler. However, triggering all WTRUs simultaneously (involving the transmission of several simultaneous DCIs) can cause congestion of the downlink control channel or DL transmissions.

[0069] By enabling the slot-level offset of the aperiodic SRS to be configured by layer 1 (L1), potential collisions between SRS transmissions and other transmissions can be avoided. Thus, the aperiodic SRS can be transmitted more flexibly and reliably with less overhead and latency. Therefore, in order to further increase the flexibility of the aperiodic SRS, it is desirable to dynamically control the SRS transmission, for example, an extended control of the SRS triggering offset.

[0070] Two-step offset indication In various embodiments, a WTRU configured for aperiodic SRS transmission can determine a slot for aperiodic SRS transmission in two steps. In an example, the WTRU can be composed of, or indicated by, two or more sets of information for determining a slot index for SRS transmission.

[0071] -RRC configuration delta offset value In various embodiments, the WTRU can receive a first configuration (e.g., SRS configuration) including a slotOffset value (k) via RRC signaling, and can receive a second configuration (e.g., slotOffset_delta) via RRC signaling. The second configuration can include one or more delta offset values that can be used to correct a first set of RRC configuration offset values (e.g., slotOffsetk received in, or determined from, the first configuration). To trigger an aperiodic SRS transmission, the WTRU can receive a media access control (MAC) control element (CE) having a downlink control information (DCI) or a field (e.g., n bits) for indicating slotOffset_delta, and each state of the DCI or MAC CE field can be used as an index for a specific configuration delta offset value (Δk) within the configured slotOffset_delta. The WTRU can determine a slot index for aperiodic SRS transmission by combining the indicated slotOffset and slotOffset_delta values, e.g., k + Δk.

[0072] Figure 3 shows an example of the SRS configuration structure in NR. As shown in Figure 3, the SRS configuration (e.g., the overall RRC SRS configuration) may be divided into three different levels of properties, namely, SRS-Config, SRS-ResourceSet, and SRS-Resource, where high-level properties, behavior properties, and resource-level properties are defined respectively.

[0073] In one embodiment, the WTRU may be configured with slotOffset_delta as part of SRS-Config. Thus, the configured slotOffset_delta may be applied to all SRS resource sets and / or SRS resources.

[0074] In one embodiment, the WTRU may be configured with slotOffset_delta as part of SRS-ResourceSet. Thus, the configured slotOffset_delta may be applied only to the SRS resources configured in that SRS resource set.

[0075] In another embodiment, the WTRU may be configured with slotOffset_delta as part of SRS-Resource configuration. Thus, the configured slotOffset_delta may be applied only to a specific SRS resource configured in the SRS resource set.

[0076] In one embodiment, the delta offset value may be configured at one or more levels of the SRS configuration. In the example, the WTRU may be configured with two delta offset values configured in SRS-ResourceSet and SRS-Resource. Thus, the received DCI or MAC CE field may indicate a specific combination of configured offset values in SRS-ResourceSet and SRS-Resource.

[0077] -MAC CE Indicated Delta Offset Value In one embodiment, the WTRU can receive a first configuration (e.g., an SRS configuration via RRC signaling) that includes a slotOffset value (k), and can receive a second configuration (e.g., slotOffset_delta) via a MAC CE that indicates one or more delta offset values. In some examples, the offset value indicated by the MAC CE can include or indicate one or more delta offset values.

[0078] As shown in FIG. 4, the WTRU can receive a MAC CE (including slotOffset_delta) before, after, or on the same slot as the DCI that triggers an aperiodic SRS transmission. In one embodiment, one or more delta offset values indicated by slotOffset_delta within the MAC CE can be valid until updated (e.g., by the network, scheduler, or gNB).

[0079] In one embodiment, the WTRU may be configured with a time validity window with reference to the reception of a physical downlink control channel (PDCCH) (or DCI) that triggers an aperiodic SRS transmission, whereby the WTRU can consider the slotOffset_delta (indicated by the MAC CE) only if, for example, the MAC CE is received within the time validity window. In an example, the time validity window may be defined by two integer values, where, with respect to "slot n" in which the PDCCH that triggers the aperiodic SRS is received, the first integer value may define the start of the window and the second integer value may define the end of the window.

[0080] In one embodiment, the WTRU can receive an explicit indication (e.g., a DCI flag) or an implicit indication (e.g., an operating mode to be considered), or alternatively, can ignore the slotOffset_delta indicated by the MAC CE.

[0081] In various embodiments, when a WTRU receives a slotOffset_delta that includes two or more delta offset values via a MAC CE, the WTRU can receive a DCI having an m-bit field to trigger an aperiodic SRS transmission. Each state of the DCI field can be used as an index for a particular configured delta offset value (Δk) within the slotOffset_delta. The WTRU can determine a slot index for the aperiodic SRS transmission by combining the indicated slotOffset and slotOffset_delta values, e.g., k+Δk.

[0082] In various embodiments, when a WTRU receives a slotOffset_delta that includes a single delta offset value via a MAC CE, the WTRU can receive a DCI to trigger an aperiodic SRS transmission. The WTRU can determine a slot index for the aperiodic SRS transmission by directly combining the indicated slotOffset and slotOffset_delta values, e.g., k+Δk.

[0083] In one embodiment, the WTRU can receive group-common DCI to trigger aperiodic SRS transmissions for several users (e.g., multiple WTRUs) simultaneously, and each WTRU within the group can receive a respective MAC CE that includes a different slotOffset_delta to indicate a corresponding delta offset value for adjusting an individual RRC-configured slotOffset.

[0084] - The delta offset value indicated implicitly In one embodiment, the WTRU can receive a first configuration (e.g., SRS configuration via RRC signaling) that includes a slotOffset value (k) and can implicitly receive or determine a second configuration. The second configuration can include one or more parameters (e.g., slotOffset_delta) that indicate a delta offset value for correcting a first configuration offset value (e.g., a value such as slotOffset received from an SRS configuration via RRC signaling). In an example, the WTRU can receive DCI scrambled with a radio network temporary identifier (RNTI) that directly corresponds to a specific slotOffset_delta value or corresponds via an index to an RRC configured slotOffset_delta set as described herein (e.g., in the previous section "RRC configured delta offset value"). In another example, the WTRU can be configured with two or more search spaces and / or CORESETs, each of which can directly correspond to a slotOffset_delta or can correspond via an index to an RRC configured slotOffset_delta set as described herein (e.g., in the previous section "RRC configured delta offset value").

[0085] Single DCI indication In various embodiments, the SRS resource set can be interchangeably referred to as an SRS resource.

[0086] - Extended SRS configuration For an aperiodic SRS configuration, the WTRU can receive a set of higher layer parameters for an SRS-ResourceSet that includes any of slotOffset, srs-ResourceSetId, AperiodicSRS-ResourceTrigger, and AperiodicSRS-ResourceTriggerList. Aperiodic SRS transmission can be triggered by WTRU-specific DCI, group common DCI, or uplink DCI.

[0087] In various embodiments, a WTRU configured for codebook or noncodebook usage may be composed of two or more SRS resource sets (e.g., multiple SRS resource sets or SRS resources), and each SRS resource set may be configured with a different slotOffset value. In one embodiment, an SRS resource set indicator (e.g., indicated by DCI or MAC CE) may indicate which SRS resource set should be used for an aperiodic SRS transmission.

[0088] In various embodiments, a WTRU configured for codebook or noncodebook usage may be composed of three or more SRS resources, and each SRS resource may be configured with a different slotOffset_resource value. Each configured slotOffset_resource may be used as a replacement for the configured slotOffset within the SRS-ResourceSet or as a correction to the configured slotOffset.

[0089] -Reuse of existing DCI formats In various embodiments, the WTRU can determine one or more slot offsets for an SRS resource set based on one or more of the following.

[0090] In one embodiment, the WTRU can determine one or more slot offsets for an SRS resource set based on one or more dedicated DCI formats. a) For example, the WTRU can dynamically determine a slot offset for an SRS resource based on one or more dedicated DCI formats (e.g., one or more of DCI format 0_3, DCI format 1_3, and DCI format 2_7). One or more dedicated DCI formats can include one or more of the following. i) Non-SUL / SUL indicator: (1) In one embodiment, when a WTRU is configured with a cell having a plurality of uplinks (ULs), the WTRU can determine one or more of the plurality of ULs based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU can determine a first uplink (e.g., a non-assisted uplink). If the WTRU receives a second indication based on the indicator, the WTRU can determine a second uplink (e.g., an assisted uplink). ii) SRS request: (1) In one embodiment, the WTRU can determine SRS transmission based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU can transmit a first set of SRS resource sets. If the WTRU receives a second indication based on the indicator, the WTRU can transmit a second set of SRS resource sets. (2) In one embodiment, the WTRU can determine SRS transmission based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU may not transmit an SRS resource set. If the WTRU receives a second indication based on the indicator, the WTRU can transmit a first set of SRS resource sets. If the WTRU receives a third indication based on the indicator, the WTRU can transmit a second set of SRS resource sets. iii) Transmit power control (TPC) command: (1) In one embodiment, the WTRU can determine the transmit power of an SRS resource set based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU can determine a first transmit power of the SRS resource set. If the WTRU receives a second indication based on the indicator, the WTRU can determine a second power of the SRS resource set. iv) Slot offset for the SRS resource set (e.g., slot offset for all triggered SRS resource sets): (1) In one embodiment, the WTRU can determine a slot offset for a triggered SRS resource set (e.g., via an SRS request) based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU can determine a first slot offset. If the WTRU receives a second indication based on the indicator, the WTRU can determine a second slot offset. (2) The determination of the slot offset can be based on one or more of the following. (a) A predefined slot offset for the indicated value (b) A preconfigured slot offset for the indicated value (c) An explicit indication of the slot offset. v) Slot offset for the SRS resource set (e.g., a specific slot offset for the SRS resource set among the triggered SRS resource sets): (1) In one embodiment, the WTRU can determine one or more slot offsets for a triggered SRS resource set (e.g., via an SRS request) based on a set of indicators. For example, if the WTRU receives a first set of indicators, the WTRU can determine a first set of slot offsets. If the WTRU receives a second set of indicators, the WTRU can determine a second set of slot offsets. (a) The number of slot offsets may be equal to the number of triggered SRS resource sets. (b) If the number of slot offsets is greater than the number of triggered SRS resource sets, the WTRU can apply the slot offset to all triggered SRS resource sets or to the triggered SRS resource sets not associated with the slot offset based on one or more of the following. (i) Do not apply a slot offset (ii) Apply the default slot offset (iii) Apply the average value of the indicated slot offsets (iv) Apply the first / last slot offset of the indicated slot offsets. (c) If the number of slot offsets is less than the number of triggered SRS resource sets, the WTRU may indicate a specific value (e.g., 0 or 1) for one or more indicators not associated with the triggered SRS resource sets. (2) The determination of the slot offset may be based on one or more of the following. (a) A predefined slot offset for the indicated value (b) A preconfigured slot offset for the indicated value (c) An explicit indication of the slot offset. (3) The WTRU may apply the determined set of slot offsets based on the determined slot offset (e.g., delta offset). For example, if the WTRU receives simultaneously a first slot offset for the triggered SRS resource set (e.g., the slot offset for all triggered SRS resource sets) and a second slot offset for the first SRS resource set of the triggered SRS resource set, the WTRU may apply the first slot offset for all triggered SRS resource sets and the second slot offset for the first SRS resource set based on the first slot offset.

[0091] In one embodiment, the WTRU may determine one or more slot offsets for an SRS resource set based on one or more existing DCI formats. a) For example, the WTRU can dynamically determine a slot offset for the SRS resource based on one or more existing DCI formats (e.g., one or more of DCI format 0_1, DCI format 0_2, DCI format 1_1, DCI format 1_2, and DCI format 2_3). b) The WTRU can determine one or more existing DCI formats as DCI for slot offset indication based on one or more of the following. i) RNTI. (1) In one embodiment, if the DCI is scrambled with a first RNTI (e.g., SRS-RNTI), the WTRU can determine the DCI as a DCI including one or more SRS slot offset indications. If the DCI is scrambled with a second RNTI (e.g., C-RNTI, CS-RNTI, etc.), the WTRU can determine the DCI as a DCI having other purposes (e.g., PDSCH / PUSCH scheduling, configured grant activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). ii) HARQ process number. (1) In one embodiment, if the HARQ process number is set to a first specific bit (e.g., all '0'), the WTRU can determine the DCI as a DCI including one or more SRS slot indications. If the HARQ process number is not set to the first specific bit, the WTRU can determine the DCI as a DCI having other purposes (e.g., PDSCH / PUSCH scheduling, configured grant activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). iii) Redundancy version. (1) In one embodiment, when the redundancy version is set to a first specific bit (e.g., all "0"), the WTRU can determine the DCI as a DCI including one or more SRS slot indications. When the redundancy version is not set to the first specific bit, the WTRU can determine the DCI as a DCI having other purposes (e.g., PDSCH / PUSCH scheduling, configured grant activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). iv) Modulation and coding scheme. (1) In one embodiment, when the modulation and coding scheme is set to a first specific bit (e.g., all "0"), the WTRU can determine the DCI as a DCI including one or more SRS slot indications. When the modulation and coding scheme is not set to the first specific bit, the WTRU can determine the DCI as a DCI having other purposes (e.g., PDSCH / PUSCH scheduling, configured grant activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). v) Frequency domain resource allocation. (1) In one embodiment, when the frequency domain resource allocation is set to a first specific bit (e.g., all "0"), the WTRU can determine the DCI as a DCI including one or more SRS slot indications. When the frequency domain resource allocation is not set to the first specific bit, the WTRU can determine the DCI as a DCI having other purposes (e.g., PDSCH / PUSCH scheduling, configured grant activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). c) If the WTRU determines the DCI as a DCI including one or more slot offset indications, one or more of the following fields can be used for the one or more slot offset indications. (1) Frequency domain resource allocation. (2) Time domain resource allocation. (3) Downlink allocation index (e.g., first and / or second). (4) Precoding information and the number of layers. d) One or more slot offsets may include one or more of the following. i) Slot offset for an SRS resource set (e.g., slot offset for all triggered SRS resource sets) (1) In one embodiment, the WTRU can determine a slot offset for a triggered SRS resource set (e.g., via an SRS request) based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU can determine a first slot offset. If the WTRU receives a second indication based on the indicator, the WTRU can determine a second slot offset. (2) The determination of the slot offset may be based on one or more of the following. (a) A predefined slot offset for a shown value (b) A preconfigured slot offset for a shown value (c) An explicit indication of the slot offset. ii) Slot offset for an SRS resource set (e.g., a specific slot offset for an SRS resource set among the triggered SRS resource sets) (1) In one embodiment, the WTRU can determine one or more slot offsets for a triggered SRS resource set (e.g., via an SRS request) based on a set of indicators. For example, if the WTRU receives a first set of indicators, the WTRU can determine a first set of slot offsets. If the WTRU receives a second set of indicators, the WTRU can determine a second set of slot offsets. (a) The number of slot offsets may be equal to the number of triggered SRS resource sets. (b) If the number of slot offsets is greater than the number of triggered SRS resource sets, the WTRU may apply the slot offset to all triggered SRS resource sets or the triggered SRS resource sets not associated with the slot offset based on one or more of the following. 1. Do not apply the slot offset. 2. Apply the default slot offset. 3. Apply the average value of the indicated slot offsets. 4. Apply the first / last slot offset of the indicated slot offsets. (c) If the number of slot offsets is less than the number of triggered SRS resource sets, the WTRU may indicate a specific value (e.g., 0 or 1) for the indicator not associated with the triggered SRS resource set. (2) The determination of the slot offset may be based on one or more of the following. (a) A predefined slot offset for the indicated value (b) A preconfigured slot offset for the indicated value (c) An explicit indication of the slot offset. (3) The WTRU may apply the determined set of slot offsets (e.g., delta offset) based on the determined slot offset. For example, if the WTRU receives a first slot offset (e.g., the slot offset for all triggered SRS resource sets) for a triggered SRS resource set and a second slot offset for the first SRS resource set of the triggered SRS resource set simultaneously, the WTRU may apply the first slot offset for all triggered SRS resource sets and the second slot offset for the first SRS resource set based on the first slot offset.

[0092] Pre-slot indication In various embodiments, the WTRU can receive an indication to transmit an SRS in a time resource belonging to a set of possible time opportunities for SRSs configured by a higher layer. These solutions may enable the network to trigger the transmission of SRSs from a number of UEs within the same slot without excessive overhead or time scheduling limitations in the DCI.

[0093] -SRS configuration time pattern The WTRU can be configured with at least one set of resources in a time domain for possible transmission of an SRS. Each such set may hereinafter be referred to as an "SRS configuration time pattern". Each SRS configuration time pattern may be associated with an index. For example, an SRS configuration time pattern may consist of a set of time symbols or a set of time slots defined by a period and an offset with respect to a slot and / or a symbol. In another example, an SRS configuration time pattern may be characterized by a bit map of a certain length, such as the start of a symbol, slot, subframe, and / or frame, each identified by a symbol number, slot number, subframe number, and frame number, respectively, and a time reference. The pattern may then be defined by a bit map that starts at the time reference and then repeats. FIG. 5 shows an example of a configuration time pattern.

[0094] The parameters defining the SRS configuration time pattern can be configured by the RRC or can be pre-defined. In one embodiment, the set of SRS configuration time patterns can be configured separately from the SRS resources. Alternatively, at least one SRS configuration time pattern can be configured as part of the SRS resource configuration. For example, at least one SRS configuration time pattern can be configured as a new "resource type".

[0095] -Variable SRS properties per transmission event In various embodiments, the WTRU may be configured with an SRS configuration time pattern, and each SRS transmission opportunity in the SRS configuration time pattern may be associated with a respective (or different) SRS configuration, a respective (or different) SRS resource set configuration, and / or a respective (or different) SRS resource configuration.

[0096] In one embodiment, the WTRU may be configured with two or more types of SRS configurations. For example, the WTRU may be configured with two or more (different) types of SRS configurations, where a first type may be used for normal SRS operation and a second type may be used when the WTRU is configured with an SRS time pattern.

[0097] In one embodiment, when each SRS transmission opportunity in the SRS configuration time pattern is associated with a different SRS resource set configuration, it may be assumed that the resource type is aperiodic. In an example, the WTRU may be configured to assume or be configured with a different usage (e.g., beamManagement, codebook, nonCodebook, and / or antennaSwitching) for each SRS transmission opportunity. For example, the WTRU may be configured to use a first transmission opportunity for beamManagement and a second transmission opportunity for antennaSwitching. In another example, for each configured SRS resource set (or respective SRS resource set configuration), the WTRU may use a respective (or different) SRS resource configuration according to the respective configured SRS resource set for the SRS transmission opportunity in the configuration pattern (e.g., the SRS configuration time pattern).

[0098] In one embodiment, when each SRS transmission opportunity in the SRS configuration time pattern is configured with the same SRS resource set but associated with different SRS resource configurations, the WTRU may use different SRS resource properties for each SRS transmission opportunity.

[0099] In an example, the WTRU can be configured with two or more types of SRS resource set configurations. For example, the WTRU can be configured with two or more (different) types of SRS resource set configurations, where a first type can be used for normal SRS operation and a second type can be used when the WTRU is configured with an SRS time pattern. In another example, the WTRU (configured with an SRS time pattern) can be configured with two or more SRS resource configurations for each SRS resource set.

[0100] In one embodiment, each SRS transmission opportunity can be configured to have a different SRS resource configuration to employ different transmission properties. In an example, the WTRU can use a different number of SRS ports for each transmission opportunity. In another example, the WTRU can use different spatialRelationInfo (e.g., spatial filters, beams) for each transmission opportunity to support multiple TRPs or to increase transmission diversity. Additionally or alternatively, the WTRU can use different cyclic shifts or sequences for each transmission event to randomize potential interference.

[0101] -Activation of SRS Configuration Time Pattern In various embodiments, the SRS configuration time pattern can be in an activated state or a deactivated state. The WTRU can determine that the set of resources for possible SRS transmissions consists only of the set of activated SRS configuration time patterns. These solutions can enable the network to modify SRS transmission opportunities more dynamically for each UE and thus modify MU-MIMO pairing candidates more efficiently.

[0102] The WTRU can determine its state by receiving RRC, MAC, or DCI signaling. For example, the WTRU can receive a MAC control element indicating which of at least one SRS configuration timing pattern is activated, using, for example, a bitmap or at least one index for the SRS configuration timing pattern. In one embodiment, the WTRU can determine a unique activated SRS configuration timing pattern based on an index received from RRC, MAC, or DCI signaling and determine that any other SRS configuration timing pattern is deactivated. When reconfiguring a set of SRS configuration timing patterns by RRC, the WTRU can determine that the initial state of each pattern is either explicitly or implicitly activated or deactivated by the RRC signaling (e.g., all are activated, all are deactivated, or only the first one is activated). When changing the bandwidth part, the WTRU can implicitly determine that the state of each pattern is either activated or deactivated.

[0103] - Triggered SRS configuration timing pattern In various embodiments, the WTRU may receive an indication (e.g., a first indication) to transmit SRS at a future time not included in the first indication. Such an indication may be applicable to a particular set of SRS configuration time patterns, such as a set of activated SRS configuration time patterns or a set explicitly included in the indication. In this case, the WTRU may determine that such a set of SRS configuration time patterns may be in a "triggered" state. The WTRU may then transmit SRS during some opportunities for the SRS configuration time pattern, provided that it is in the triggered state. Such transmissions may occur subsequent to the receipt of a second indication or another event (e.g., the start of a COT), as described below. After transmitting SRS for a configuration time pattern, the WTRU may determine that such a pattern is in a "not triggered" state. The WTRU may also determine that the pattern is in a "not triggered" state when the bandwidth part changes or when a timer started when the pattern was set to the "triggered" state expires. When reconfiguring a set of SRS configuration time patterns by RRC or when activating a set of SRS configuration time patterns, the WTRU may determine whether the initial state of each pattern is triggered or not triggered.

[0104] -Triggering of SRS transmission The WTRU may transmit SRS during at least one opportunity defined by at least one SRS configuration time pattern, based on the following.

[0105] In one embodiment, the WTRU may transmit during all opportunities defined by the union of SRS configuration time patterns, or alternatively, by the union of activated SRS configuration time patterns.

[0106] In one embodiment, the WTRU may transmit in a subset of opportunities for the SRS configuration time pattern upon receipt of DCI, subsequent to the start of a COT, or after successful access to a channel.

[0107] The following may be signaled by the MAC (e.g., MAC EC) or RRC message as indicated in the DCI, or may be pre-defined: 1) a set of SRS configuration time patterns in which SRS is transmitted; 2) the number of opportunities for SRS to be transmitted for each pattern or set of patterns; and / or 3) the first opportunity for SRS to be transmitted for each pattern or set of patterns. For example, such an opportunity may be the Nth opportunity following several symbols S following the last symbol of the PDCCH in which the DCI is decoded, where N and S may be pre-defined or indicated in the DCI.

[0108] In various embodiments, the set of SRS configuration time patterns may be limited to a subset of the activated patterns and / or triggered patterns.

[0109] - An indication to transmit within the Channel Occupancy Time (COT) In various embodiments, the WTRU can receive an indication to transmit SRS in the current or next slot of the COT. For example, as shown in Figure 6, the WTRU can receive an indication via DCI or MAC CE to transmit SRS in the next UL resource of the current COT. In another example, the WTRU can receive an indication to transmit SRS in a specific (e.g., the first UL resource) UL resource of a subsequent or future COT. In this example, the WTRU may not need to receive a further indication to transmit SRS and can do so when it determines or is indicated that a subsequent or future COT has started.

[0110] The WTRU can receive an indication that it can transmit the SRS on a particular (e.g., first) UL resource of the COT acquired by the UE. In such a case, the WTRU can transmit the SRS on the UL resource when it has successfully acquired the channel and the COT acquired by the UE starts. In some cases, as shown in FIG. 7, the gNB can recognize the specific timing at which the WTRU attempts to acquire the channel and start the COT (e.g., when the gNB has permitted a specific resource on which the WTRU can attempt to acquire the channel). In other cases, the WTRU can autonomously determine when to acquire the channel depending on whether it has data to transmit (e.g., on a configured grant resource). Thus, the WTRU can indicate to the gNB when the transmission includes an SRS that has been previously triggered. For example, the WTRU can receive a command to transmit the SRS on a particular UL resource of the next UE-acquired COT. The WTRU can attempt to acquire the COT only when it has data to transmit on the configured grant. The WTRU can indicate to the gNB whether the WTRU-acquired COT includes SRS transmission. The WTRU can implicitly indicate the presence of the SRS in at least one of the stand-alone transmission, configured grant UCI (CG-UCI), and PUCCH transmission to the gNB via the SRS parameters.

[0111] In one embodiment, upon receiving an indication to transmit the SRS from the network (e.g., gNB), the WTRU can attempt to acquire the channel on the CG resource at the next appropriate timing regardless of whether the WTRU has data to transmit. Thus, if the WTRU successfully acquires the channel, it can transmit only the SRS on the CG resource.

[0112] In one embodiment, the WTRU may be configured with SRS transmission opportunities (e.g., SRS configuration time patterns) as defined previously. Such opportunities may occur periodically or may be defined at specific timing instances (and optionally at specific frequency positions). Upon receiving an indication to transmit SRS on future UL resources, the WTRU may transmit the SRS on the next upcoming SRS transmission opportunity. The WTRU may determine the appropriate SRS transmission opportunity for transmitting the SRS as one that satisfies an offset indicated by the gNB. For example, the WTRU may determine to transmit the SRS on the first SRS transmission opportunity that occurs after the time of receiving the indication + the indicated offset timing. In another example, the WTRU may determine to transmit the SRS on an SRS transmission opportunity that starts before the time of receiving the indication and ends by the time indicated by the offset.

[0113] -WTRU - to - WTRU coordination for SRS transmission In various embodiments, the WTRU may obtain the COT, have resources for the WTRU to transmit SRS, and determine that the WTRU needs to transmit SRS. The WTRU may, for example, transmit a WTRU - to - WTRU (or UE - to - UE) indication indicating that the next SRS transmission resource will be used for SRS transmission before transmitting the SRS. Other UEs may listen for such transmissions from neighboring UEs. Upon receiving a UE - to - UE indication, other UEs may transmit SRS on the same resources. This may enable multi - UE transmission of SRS, optionally to support MU - MIMO.

[0114] -LBT for triggered SRS transmission In various embodiments, the WTRU may use the channel only for transmitting SRS. In such cases, the WTRU may not need to perform channel access (e.g., Listen Before Talk (LBT)) before transmitting the SRS. In other cases, if the WTRU has data to transmit on a resource adjacent to the SRS resource, the WTRU may perform channel access (e.g., LBT). The choice of LBT type to perform may depend on at least one of the presence of data, the type of data, the timing of the UL transmission relative to the previous DL transmission (e.g., a gap), or an indication received by the WTRU.

[0115] - SRS transmission indication In various embodiments, the WTRU may receive an indication for transmitting SRS in the current or a subsequent COT. Such an indication may be received by DCI or MAC CE. The indication may reuse other control channel transmissions. For example, the WTRU may receive an indication for transmitting SRS in the DCI used to indicate that the COT is active. For example, the GC-PDCCH indicating an active COT may also be used to indicate to the WTRU to transmit the SRS (optionally with a timing offset). The timing offset may be determined according to the COT timing.

[0116] - Multiple timing offsets In various embodiments, the indication for SRS transmission may include or map to multiple timing offsets. The WTRU may determine a timing offset according to at least one of the following. - Whether the channel is acquired for the intended SRS transmission time (e.g., whether there is an active COT). In this example, the WTRU may transmit the SRS using the first timing offset at which the channel is available for transmission. - Parameters of the active COT. For example, if the WTRU obtains a first set of unlicensed subbands for COT, the WTRU can use a first timing offset for SRS transmission. If the WTRU obtains a second set of unlicensed subbands for COT, the WTRU can use a second timing offset for SRS transmission. - The type of data that the WTRU needs to transmit (e.g., depending on the content of its buffer). For example, higher priority data may be associated with a first timing offset, and lower priority data may be associated with a second timing offset. - Whether the WTRU has data to transmit. - The priority of SRS transmission. For example, different SRS transmissions can be assigned different priorities.

[0117] Two-stage DCI indication In various embodiments, the WTRU can transmit SRS based on the reception of an SRS configuration trigger and (e.g., in combination) an SRS transmission trigger. In some examples, the mechanism of two-stage DCI indication can include using the SRS configuration trigger and the SRS transmission trigger in different downlink control channels (e.g., multiple DCIs or PDCCHs) for dynamic aperiodic SRS control and SRS transmission. In some cases, the mechanism of two-stage DCI indication can reduce the overload of PDCCH traffic.

[0118] FIG. 8 shows an example of a two-stage DCI indication mechanism. In the example, the WTRU can receive an SRS configuration trigger in a first DCI (e.g., WTRU-specific DCI). The WTRU can receive an SRS transmission trigger in a second DCI (e.g., group common DCI). Each DCI can be received in a corresponding PDCCH. The PDCCH can be received in a UE-specific search space or a common search space (SS). In the example, the SRS configuration trigger may be received in a WTRU-specific SS, and the SRS transmission trigger may be received in a common SS. The WTRU can be configured with an RNTI (e.g., UE-specific RNTI or group RNTI) that can be used (e.g., specifically used) for the SRS transmission trigger. The WTRU can be configured with an RNTI (e.g., UE-specific RNTI or group RNTI) that can be used (e.g., specifically used) for the SRS configuration trigger. The cyclic redundancy check (CRC) of the DCI can be scrambled with the RNTI described herein. The WTRU can receive the DCI using the RNTI (e.g., correctly decode the DCI using the RNTI).

[0119] In another example, the WTRU can receive one trigger in a MAC-CE and another trigger in a DCI. For example, the WTRU can receive an SRS configuration trigger in a MAC-CE. The WTRU can receive an SRS transmission trigger in a DCI. In another example, the WTRU can receive each of the triggers in a corresponding MAC-CE (e.g., a different MAC-CE).

[0120] A WTRU may be composed of one or more sets of resources that can be used for SRS transmission. A set of resources may include one or more resources in frequency and / or time (e.g., a pattern of resources in frequency and / or time). The frequency resources may be, or may include, one or more resource elements (REs), resource blocks (RBs), or physical RBs (PRBs). The configuration of a set of resources may identify the frequency resources (e.g., frequency location) for SRS transmission and / or the time location for SRS transmission. The time location may include, for example, which symbol during a duration such as a start symbol, number of symbols, slot, number of slots, a pattern of symbols and / or slots, etc.

[0121] In various embodiments, a resource set (e.g., an SRS resource set) and a set of resources (e.g., an SRS resource) may be used interchangeably herein.

[0122] In various embodiments, an SRS configuration trigger may identify one or more of a configured set of SRS resources that can be used for SRS transmission. By identifying a set of SRS resources, the trigger may identify the resources in time and / or frequency for SRS transmission (e.g., via the configuration of the resource set). The identified resources may be within one or more slots.

[0123] In an example, a resource set may have a slot offset associated therewith (e.g., a resource set may be composed of slot offsets). An SRS configuration trigger may indicate whether to use the associated (e.g., configured) slot offset or to ignore the slot offset, e.g., whether to wait for an SRS transmission trigger to be sent. If the SRS configuration trigger indicates to use the slot offset, the WTRU may transmit the SRS on the indicated resource within the slot indicated by the slot offset. The slot offset may indicate an offset within the slot from the slot in which the PDCCH (or MAC-CE) carrying the SRS configuration trigger is received. If the SRS configuration trigger indicates not to use the slot offset, the WTRU may not transmit the SRS in response to receiving the SRS configuration trigger. The WTRU may transmit the SRS in response to receiving an SRS transmission trigger that may be received after the SRS configuration trigger.

[0124] In another example, the WTRU may not transmit the SRS in response to receiving the SRS configuration trigger. The WTRU may understand, for example, that the trigger is for configuration and not for transmission, regardless of whether the SRS resource set is configured or associated with a slot offset.

[0125] In an example, an SRS resource set (e.g., an SRS resource set for use with a configuration trigger and a transmission trigger) may not be configured using a slot offset or may not have a slot offset associated therewith. The WTRU may not transmit the SRS in response to receiving the SRS configuration trigger. The WTRU may transmit the SRS in response to receiving an SRS transmission trigger that may be received after the SRS configuration trigger.

[0126] The SRS transmission trigger may indicate one or more of a slot offset, number of slots, pattern of slots, first slot, etc. The SRS transmission trigger may indicate one or more SRS time-related parameters. The time-related parameters may be a slot, slot offset, start slot, number of slots, pattern of slots, start symbol, number of symbols, pattern of symbols, etc.

[0127] In an example, the WTRU may use the SRS configuration trigger to determine one or more (e.g., all) of the frequency-related parameters of SRS transmission. The WTRU may use the SRS configuration trigger to determine at least some of the time-related parameters for SRS transmission. The WTRU may use the SRS transmission trigger to determine at least some (e.g., some others) of the time-related SRS parameters.

[0128] The value of the time-related parameter indicated by the transmission trigger may override the value of the time-related parameter indicated by the configuration trigger. For example, the WTRU may receive an indication of a first value of a time-related parameter via the configuration trigger. The WTRU may receive an indication of a second value of the time-related parameter via the transmission trigger. The WTRU may use the second value of the time-related parameter, for example, when determining when to transmit the SRS.

[0129] The WTRU may receive the SRS configuration trigger in or with the UL grant DCI or DL grant DCI. The WTRU may receive the SRS transmission trigger in or with the UL grant DCI or DL grant DCI.

[0130] The WTRU can receive an SRS transmission trigger in DCI that does not include or is not used for a UL grant or a DL grant. The WTRU can receive an SRS transmission trigger in DCI that can be used to provide one or more of a slot format indicator (SFI), a channel occupancy time (COT) indication, and / or an SS switching indication. The COT indication can indicate the remaining time in the COT, e.g., the COT obtained by the gNB. When the WTRU receives an SRS transmission trigger in DCI that can be used to indicate an SFI, a COT indication, and / or an SS switch, one or more of the indications for the SFI, the COT indication, and / or the SS switch may or may not be present in the DCI.

[0131] The WTRU can transmit the SRS based on receiving the SRS transmission trigger or in response to the SRS transmission trigger. The WTRU can transmit the SRS in response to receiving the SRS transmission trigger. When the UE transmits the SRS based on receiving the SRS transmission trigger or in response to the SRS transmission trigger, the WTRU can transmit the SRS on a resource within the slot indicated by the slot offset. The offset can be the offset within the slot from the slot in which the PDCCH (or MAC-CE) carrying the SRS transmission trigger is received. In an example, the slot offset used by the WTRU can be indicated by the SRS transmission trigger. The slot offset can be directly indicated by the transmission trigger. For example, the slot offset can be included in the DCI or MAC-CE that provides the transmission trigger. The slot offset can be indicated by an index or other indicator provided by the transmission trigger (e.g., by the DCI or MAC-CE). The index or other indicator can indicate a configured value from a set of configured values for the slot offset.

[0132] In an example, the slot offset used by the WTRU can be a configured slot offset. For example, the slot offset may be included in the configuration of the SRS resource set. The configuration trigger may indicate the resource set. The transmission trigger may indicate to use the slot offset configured for the resource set (e.g., use it for the transmission trigger).

[0133] In another example, the SRS resource set can have a set of slot offsets configured for the SRS resource set. The transmission trigger can indicate which slot offset to use. If only one slot offset is configured for the resource set, an indication of which to use (e.g., when that resource set is indicated) may not be required, used, and / or provided.

[0134] The WTRU can transmit SRS based on, or using, the time resources, time-related parameters, and / or frequency resources indicated by a combination of the configuration trigger and the transmission trigger. For example, the WTRU can transmit on the indicated frequency resources. The WTRU can transmit in symbols and slots based on the indicated time-related parameters. The WTRU can transmit, for example, according to one or more symbols, one or more slots, and / or a set or pattern of symbols and / or slots based on the indicated time-related parameters.

[0135] One or more WTRUs can receive individual SRS configuration triggers. An SRS transmission trigger that can indicate a slot offset can be received by one or more WTRUs. One or more WTRUs can use the received slot offset and transmit SRS in the same slot. One or more WTRUs can transmit SRS according to the resources and transmission parameters indicated by their respective configuration triggers.

[0136] SRS transmission parameters (e.g., including time and / or frequency resources, or otherwise) may be provided by a configuration trigger and / or a transmission trigger. The WTRU can transmit SRS according to the received transmission parameters. The transmission parameters indicated by the transmission trigger can override the transmission parameters indicated by the configuration trigger.

[0137] The SRS resource set may include a trigger mode indication (e.g., may be configured with a trigger mode indication). The trigger mode indication may indicate when, or based on which trigger, to use one or more parameters, e.g., time-related parameters for transmitting SRS. The trigger mode may be indicated by the SRS resource set indicated by the SRS configuration trigger and / or the SRS transmission trigger received by the WTRU.

[0138] For example, the trigger mode indication may indicate whether to use the configured slot offset and / or one or more other parameters (e.g., time-related parameters) when a request indicating a configuration trigger or a resource set is received. The WTRU can use the trigger mode indication configured for the resource set to determine when (e.g., for which SRS trigger or request, or in response thereto) to transmit SRS, e.g., according to the SRS resource set.

[0139] For example, in the case of the first trigger mode, the WTRU can transmit SRS in response to an SRS configuration trigger or an SRS request or a trigger received in a UL or DL grant. In the case of the second trigger mode, the WTRU may not be required to transmit SRS in response to an SRS configuration trigger or an SRS request or a trigger received in a UL or DL grant. In the case of the second trigger mode, the WTRU can transmit SRS in response to an SRS transmission trigger that may be after the SRS configuration trigger. In the case of the second trigger mode, the WTRU can transmit SRS in response to an SRS transmission trigger or an SRS request or a trigger that is not received together with a UL or DL grant.

[0140] The SRS transmission can be considered as a pending SRS transmission after receiving the SRS configuration trigger. The SRS configuration trigger or the pending SRS transmission can be cancelled or can expire after the expiration time.

[0141] For example, if a WTRU can receive an SRS configuration trigger in a first slot and does not receive a transmission trigger for a number of slots exceeding a threshold number, the WTRU can cancel the SRS transmission associated with the SRS configuration trigger. If the WTRU receives an SRS transmission trigger and does not have a pending SRS transmission (e.g., based on an unexpired SRS configuration trigger), the WTRU can ignore the SRS transmission trigger. The number of slots is an example. For the expiration time and / or threshold, another time unit, such as a symbol, or milliseconds, etc. can be used.

[0142] In various embodiments, a threshold can be configured. The configuration of the threshold can be included in the configuration of the SRS resource set.

[0143] The SRS transmission trigger can be used when the SRS configuration trigger is received within a configured number of slots or configured amount of time before the reception of the SRS transmission trigger. If a WTRU can receive an SRS transmission trigger (e.g., in a slot) and the WTRU does not receive an SRS configuration trigger within a number of slots or within the amount of time or window before the SRS transmission trigger, the WTRU can ignore the SRS transmission trigger. For example, the WTRU may not transmit the SRS based on the transmission trigger or in response to the transmission trigger. The number of slots or amount of time can be the configured threshold number of slots or configured threshold amount of time. The number of slots or amount of time can be the configured window of slots or configured time window.

[0144] In various embodiments, a threshold (e.g., a slot or time threshold), or a window of slots, or a time (e.g., in milliseconds) may be configured via at least one of an SRS configuration trigger, an SRS transmission trigger, an SRS resource set, and / or a separate configuration. Time and amounts of time may be used interchangeably.

[0145] Mode Selection for SU / MU-MIMO - Operation Mode In various embodiments, one or more operation modes may be used, defined, or configured for an aperiodic SRS trigger based on an aperiodic SRS trigger offset determination, where the aperiodic SRS trigger offset may be an offset between a first slot in which a WTRU can receive an SRS trigger indication and a second slot in which the WTRU can send or transmit a triggered SRS resource and / or resource set. Hereinafter, the aperiodic SRS trigger offset may be interchangeably referred to as an SRS offset, a slot offset (or slotOffset), and / or a trigger offset.

[0146] In an operation mode, the SRS offset may be determined, used, or selected in a semi-static manner. For example, the SRS offset may be configured for each SRS resource set or SRS resource, and the associated SRS offset may be used or determined when the SRS resource set or SRS resource is triggered. In various embodiments, a set of SRS offset values may be predefined or configured, and one SRS offset value in the set may be selected, used, or configured for an SRS resource set or SRS resource. In an example, one or more SRS resources may be associated with an SRS resource set. The SRS offset may be configured or determined for the SRS resource set, and one or more SRS resources associated with the SRS resource set may use the SRS offset value configured for the associated SRS resource set.

[0147] In the operation mode, the SRS offset can be determined, used, selected, or indicated in a dynamic manner. For example, the SRS offset for a triggered SRS resource (or SRS resource set) can be determined dynamically based on an indication. One or more of the following may apply: (1) The SRS offset indication can be signaled with associated control information (e.g., downlink control information or sidelink control information). And / or (2) The SRS offset indication may be a delta offset from a configured SRS offset for the SRS resource (or SRS resource set).

[0148] In the operation mode, the SRS offset may be implicitly determined based on one or more system and / or UE-specific parameters, which may include at least one of identification information (e.g., cell id, UE-id, BWP-id), system configuration (e.g., subcarrier spacing, TDD UL / DL configuration, number of carriers, etc.), and scheduling parameters (e.g., MCS, scheduled bandwidth, configured or indicated DM-RS pattern, etc.).

[0149] -Determination of the operation mode In one embodiment, the operation mode for SRS triggering (e.g., SRS trigger mode) can be determined based on the used, selected, or determined uplink transmission mode. In various embodiments, the SRS trigger mode can be used to distinguish different modes of uplink transmission, e.g., single-user (SU) mode and multi-user (MU) mode of uplink transmission. In an example, the operation mode for SRS triggering can be applied in the scheme described herein according to the SU / MU operation mode. For example, the uplink transmission mode (e.g., SU / MU mode of uplink transmission) or the SRS trigger mode can be determined based on one or more of the following. ● The DCI format used for SRS triggering. For example, when SRS transmission is triggered by a first DCI format (e.g., DCI format 0_1), a first SRS trigger mode may be used, and when SRS transmission is triggered by a second DCI format (e.g., DCI format 1_1), a second SRS trigger mode may be used. ● The number of DM-RS CDM groups for which no data is indicated. For example, this is the case when SRS transmission is triggered by a DCI (e.g., DCI format 0_1) in which the number of DMRS CDM groups without data is greater than a threshold. ○ The threshold may vary based on the DMRS type, the number of layers, and / or the number of codewords. ● The configured DMRS type. For example, the first SRS trigger mode may be used when a first DMRS type is configured for UL transmission in the BWP (e.g., DMRS type-1), and the second SRS trigger mode may be used when a second DMRS type is configured for UE transmission in the BWP (e.g., DMRS type-2). ● The configured DMRS density. For example, the first SRS trigger mode may be used when the DMRS density (e.g., time density) is less than a threshold, and the second SRS trigger mode may be used when the DM-RS density is greater than or equal to the threshold. ○ The DMRS density in this specification may be the number of DMRS symbols within a slot. ● The maximum number of configured MIMO layers. For example, the first SRS trigger mode may be used when the maximum number of MIMO layers configured for the BWP is less than a threshold, and the second SRS trigger mode may be used when the maximum number of MIMO layers configured for the BWP is greater than or equal to the threshold.

[0150] In one embodiment, the SRS trigger mode may be determined based on the configuration of a bandwidth part (BWP). For example, a first SRS trigger mode may be configured, used, or determined for a first BWP, and a second SRS trigger mode may be configured, used, or determined for a second BWP. In some examples, the SRS trigger mode may be determined based on any of the associated BWP-id, the number of configured SRS resources and / or SRS resource sets, the number of SRS antenna ports (e.g., maximum), and the SRS configuration for the BWP.

[0151] In one embodiment, the SRS trigger mode may be determined based on the identification information of the associated search space and / or CORESET. For example, the SRS trigger mode may be determined based on in which search space and / or CORESET the WTRU received the SRS trigger. If the UE receives an SRS trigger (e.g., first search space identification information or CORESET identification information) in a first search space and / or CORESET, the WTRU may use or determine a first SRS trigger mode, and if the WTRU receives an SRS trigger (e.g., second search space identification information or CORESET identification information) in a second search space and / or CORESET, the WTRU may use or determine a second SRS trigger mode. In some cases, the SRS trigger mode may be configured for the search space and / or CORESET.

[0152] In one embodiment, the SRS trigger mode may be determined based on the number of bits configured for the SRS request field in the DCI. For example, if the number of bits for the SRS request field in the DCI is 2 bits or less, a first SRS trigger mode may be used or determined, and otherwise, a second SRS trigger mode may be used. In some examples, when the SRS request bit field has more than 2 bits, the first 2 bits may be used to indicate a set of triggered SRS resources, and the remaining bits may be used to indicate an SRS trigger offset value.

[0153] Extended Aperiodic SRS Transmission In various embodiments, the WTRU may be indicated (or instructed) or configured to operate in one or more modes of aperiodic SRS transmission, such as a legacy mode (e.g., the first mode of FIG. 9) and / or an extended mode (e.g., the second mode of FIG. 9). In some examples, the WTRU may be configured semi-statically or dynamically to operate in one of one or more modes of aperiodic SRS transmission. For example, in the case of dynamic operation, the WTRU may be explicitly indicated (e.g., by DCI) to the WTRU by L1 signaling to operate in the extended mode. Additionally or alternatively, the WTRU may be able to implicitly determine its mode of aperiodic SRS transmission.

[0154] In an example, referring to FIG. 9, a mechanism / procedure for mode determination for aperiodic SRS transmission is provided. In this example, the WTRU may determine or select an operating mode (or mechanism / procedure) for aperiodic SRS transmission based on (or using) explicit or implicit information.

[0155] In one embodiment, for SRS transmission (e.g., aperiodic SRS transmission), the WTRU may receive an SRS configuration of one or more SRS resource sets, where each SRS resource set is associated with a set of slot offsets and / or slot offset deltas. The WTRU may receive an SRS request / indication in DCI, and the SRS request may indicate an SRS resource set from one or more SRS resource sets. The WTRU may determine a mode (or scheme) for SRS transmission based on, for example, any combination of 1) the search space or CORESET in which the DCI is received, 2) the DCI format, 3) an indication within the DCI, and / or 4) the RNTI used to scramble the DCI CRC.

[0156] In an example, if the WTRU determines to use a first SRS mode (e.g., a legacy mode, or the first mode of FIG. 9), the WTRU can determine (or select) one or more slots for SRS transmission based on (or using) the slot offsets associated with each SRS resource set. In another example, if the WTRU determines to use a second SRS mode (e.g., an extended mode, or the second mode of FIG. 9), the WTRU can determine (or select) at least one slot offset delta from a set of slot offset deltas associated with each SRS resource set. In some cases, the WTRU can determine (or select) at least one slot offset delta based on a received indication (e.g., in the DCI described above, another DCI, or a MAC CE), or determined information (e.g., from an RNTI such as the RNTI used to scramble the DCI CRC). The WTRU can determine the slot for SRS transmission based on (or using) the slot offset (associated with the SRS resource set) and the determined slot offset delta. The WTRU can transmit SRS on one or more resources of the SRS resource set in the determined slot.

[0157] In various embodiments, methods, apparatuses, and / or systems for flexible aperiodic RS (e.g., SRS) transmission in wireless communication are disclosed. In one embodiment, a method for wireless communication (e.g., implemented in a WTRU 102) includes receiving configuration information of one or more SRS resource sets, wherein each SRS resource set of the one or more SRS resource sets is associated with a set of slot offset and slot offset delta; receiving a DCI indicating an SRS request indicating an SRS resource set among the one or more SRS resource sets; determining an SRS configuration from a set of SRS configurations for SRS transmission; determining a slot for transmitting the SRS based on the determined SRS configuration; and transmitting the SRS using the resources of the indicated SRS resource set in the determined slot.

[0158] In one embodiment, the SRS configuration is determined from a set of SRS configurations for SRS transmission based on any one of 1) a search space or CORESET in which the DCI is received, 2) a DCI format, 3) an indication in the DCI, and / or 4) a radio network temporary identifier (RNTI) used to scramble a cyclic redundancy check (CRC) for the DCI. In an example, the slot for transmitting the SRS is determined based on a slot offset associated with the indicated SRS resource set.

[0159] In one embodiment, the method may also include determining a slot offset delta from a set of slot offset deltas associated with the indicated SRS resource set, wherein the slot for transmitting the SRS is determined based on 1) a slot offset associated with the indicated SRS resource set and 2) the determined slot offset delta. In an example, the slot offset delta is determined from the set of slot offset deltas based on any of 1) received configuration information, 2) received DCI, 3) determined SRS configuration, 4) the search space or CORESET in which the DCI is received, 5) the DCI format, 6) an indication in the DCI, 7) the RNTI used to scramble the cyclic redundancy check (CRC) for the DCI, or 8) a MAC CE. In one embodiment, the slot for transmitting the SRS is determined based on a slot offset associated with the SRS resource set and the determined slot offset delta. In one embodiment, configuration information for one or more SRS resource sets is received via radio resource control (RRC) signaling.

[0160] In one embodiment, a method for wireless communication (e.g., implemented in a WTRU 102) includes receiving a first SRS configuration including first slot information, receiving a second SRS configuration including second slot information, and determining a slot index for SRS transmission based on the first slot information and the second slot information. The method may also include transmitting an aperiodic SRS using the determined slot index. In an example, the first slot information includes a slot offset value. In an example, the second slot information includes one or more delta offset values, and the one or more delta offset values are used to correct the slot offset value. In an example, the method may include combining the slot offset value and the one or more delta offset values. In an example, the second SRS configuration is received via DCI or MAC CE. In an example, at least one of the first SRS configuration and the second SRS configuration is an RRC configuration.

[0161] In one embodiment, a method for wireless communication (e.g., implemented in a WTRU 102) includes receiving a set of parameters for an SRS resource set, determining that an aperiodic SRS transmission is triggered based on DCI, and transmitting an aperiodic SRS based on the set of parameters. In an example, the aperiodic SRS transmission is triggered by WTRU-specific DCI, group-common DCI, or uplink DCI. In one embodiment, the method may include determining one or more slot offsets for the SRS resource set. In an example, the one or more slot offsets are determined based on one or more DCI formats.

[0162] In one embodiment, a method for wireless communication (e.g., implemented in a WTRU 102) includes receiving an indication to trigger an aperiodic RS transmission, determining, based on the indication, a slot and a new slot format for the aperiodic RS transmission, where the new slot format indicates a different slot format used for the slot, and transmitting the aperiodic RS in the slot using the new slot format.

[0163] Slot Format Indication for Aperiodic SRS Transmission In NR, in the case of TDD operation, a WTRU may be configured (e.g., by a higher layer) to operate in a specific pattern of uplink (UL), downlink (DL), and / or flexible (F) slots, and / or a specific pattern of UL, DL, and flexible (F) symbols per slot. For example, the RRC parameter tdd-UL-DL-ConfigurationCommon provides a general pattern of slots within a pre-configured period.

[0164] In various embodiments, the WTRU may further be provided with the parameter tdd-UL-DL-ConfigurationDedicated to override flexible (F) symbols on a slot-by-slot basis over the number of slots indicated by tdd-UL-DL-ConfigurationCommon. For a set of symbols of a slot indicated as flexible by tdd-UL-DL-ConfigurationCommon or tdd-UL-DL-ConfigurationDedicated, the WTRU may receive DCI format 2_0 having an SFI index field value indicating a new slot format [2].

[0165] In various embodiments, the WTRU may be configured to operate in SFI-Aperiodic mode. When the SFI-Aperiodic mode is configured, for example, when the WTRU receives an L1 or L2 command that triggers an aperiodic RS signal transmission, the received information element (IE) may also serve as a slot format indicator. In the example, the slot format indicator may be used to indicate / determine a change in format. For example, the WTRU may change the format of the slot indicated for the aperiodic RS transmission to another slot format required for the RS transmission based on the information provided by the slot format indicator.

[0166] In one embodiment, if the slot indicated for UL (or DL) aperiodic RS transmission is already a UL (or DL) slot, the slot format indicated by the IE may be of only the F type, and the indicated slot format (e.g., the F type) has a configuration of UL, DL, and / or F symbols.

[0167] In one embodiment, if the slot indicated for aperiodic RS transmission is a UL slot, the indicated slot type may be DL or F, and the newly indicated DL or F slot format may override the previous slot type and replace it with a new configuration of UL, DL, and / or F symbols. In another example, if the slot indicated for aperiodic RS transmission is a DL slot, the indicated slot type may be UL or F, and the newly indicated UL or F slot format may override the previous slot type and replace it with a new configuration of UL, DL, and / or F symbols.

[0168] In one embodiment, if the slot indicated for aperiodic SRS transmission is an F slot, the indicated slot type may be DL, UL, or F type (e.g., a new F type), and the newly indicated DL, UL, or F slot format may override the previous slot type and replace it with a new configuration of UL, DL, and / or F symbols. For example, a WTRU may determine that the slot indicated for aperiodic SRS transmission is an F slot having a first F slot type, and the WTRU may determine that the indicated slot format is a DL slot type, a UL slot type, or a new F slot type (e.g., a second F slot type different from the first F slot type), and the newly indicated DL, UL, or F slot format / type (e.g., a new configuration of UL, DL, and / or F symbols) may be used for the slot indicated for aperiodic SRS transmission.

[0169] In various embodiments, the WTRU may be configured to operate in SFI_aperiodic mode. In an example, when the SFI_aperiodic mode is configured, when the WTRU receives DCI that triggers an aperiodic SRS transmission, the received DCI may also serve as a slot format indicator. In an example, the slot format indicator may be used to indicate / determine a format change. For example, the WTRU may change the format of the slot indicated for the aperiodic SRS transmission to another slot format suitable for SRS transmission based on the information provided by the slot format indicator. Thus, the WTRU may not need to receive a separate DCI format (e.g., DCI format 2_0) to adapt the slot indicated for SRS transmission to a slot having a UL transmission opportunity.

[0170] In one embodiment, if the slot indicated for the aperiodic SRS transmission is already a UL slot, the slot format indicated by the IE may be only of the F type, and the indicated slot format (e.g., the F type) has a configuration of UL, DL, and / or F symbols.

[0171] In one embodiment, if the slot indicated for the aperiodic RS transmission is a UL slot, the indicated slot type may be DL or F, and the newly indicated DL or F slot format may override the previous slot type and replace it with a new configuration of UL, DL, and / or F symbols. In another example, if the slot indicated for the aperiodic RS transmission is a DL slot, the indicated slot type may be UL or F, and the newly indicated UL or F slot format may override the previous slot type and replace it with a new configuration of UL, DL, and / or F symbols.

[0172] In one embodiment, if the slot indicated for aperiodic SRS transmission is an F slot, the indicated slot type may be a DL, UL, or F type (e.g., a new F type), and the newly indicated DL, UL, or F slot format may override the previous slot type and replace it with a new configuration of UL, DL, and / or F symbols. For example, a WTRU may determine that the slot indicated for aperiodic SRS transmission is an F slot having a first F slot type, and the WTRU may determine that the indicated slot format is a DL slot type, a UL slot type, or a new F slot type (e.g., a second F slot type different from the first F slot type), and the newly indicated DL, UL, or F slot format / type (e.g., a new configuration of UL, DL, and / or F symbols) may be used for the slot indicated for aperiodic SRS transmission.

[0173] In various embodiments, the IE that triggers aperiodic RS transmission may carry a field (e.g., an SFI index) indicating a specific slot format. In one embodiment, to reduce the overhead associated with the IE, instead of the SFI index, the WTRU may receive a new index (e.g., SFI_index_aperiodic) that can have a size smaller than the SFI index. In an example, the new index (e.g., SFI_index_aperiodic) may select only a subset of the slot format options from the original SFI table (e.g., as shown in reference [2]).

[0174] In another embodiment, the WTRU may be configured (e.g., by a higher layer) with one or more specific slot formats for aperiodic RS transmission, and each configured slot format may correspond to a preferred slot format for transmission, e.g., UL, DL, or F. Thus, when the WTRU receives an IE that triggers an aperiodic RS transmission, the WTRU may use a specific slot format configured by the higher layer.

[0175] Figure 10 shows an example of configuring a slot format indication by triggering DCI for aperiodic SRS transmission. In some cases, even if the slot indicated for SRS transmission may be a flexible (F) slot having some symbols allocated for UL transmission, the indicated slot may still not have a sufficient number of symbols to correspond to the SRS transmission. To correspond to the SRS transmission, the WTRU may receive, determine, or configure a slot format indication by triggering DCI for aperiodic SRS transmission. Referring to Figure 10, in the example as shown in Figure 10(a), triggering the DCI may change the slot type (e.g., from an F type having fewer UL symbols) (e.g., to a full UL slot having only UL symbols). In another example, as shown in Figure 10(b), triggering the DCI may change the slot format (e.g., a flexible format having fewer UL symbols) to another flexible format having more UL symbols.

[0176] The features and elements are described above in a particular combination, but it will be understood by those skilled in the art that each feature or element can be used alone or in any combination with other features and elements. Further, 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 processor. Examples of non-transitory computer-readable storage media include, but are not limited to, magnetic media such as read only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, internal hard disks, and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A radio frequency transceiver for use in a WTRU102, UE, terminal, base station, RNC, or any host computer can be implemented using a processor associated with software.

[0177] Furthermore, in the above embodiments, other devices including a processing platform, computing system, controller, and processor are described. These devices can include at least one central processing unit (“CPU”) and memory. According to the convention of those skilled in the art in the technical field of computer programming, references to operations, and symbolic representations of operations or instructions can be implemented by various CPUs and memories. Such operations and operations or instructions may be referred to as “executed,” “executed by a computer,” or “executed by a CPU.”

[0178] Those skilled in the art will understand that operations and symbolically represented operations or instructions involve the manipulation of electrical signals by a CPU. An electrical system represents data bits that can cause a resulting conversion or reduction of electrical signals, maintains the data bits at memory locations of a memory system, thereby reconfiguring or otherwise changing the operation of the CPU and the processing of other signals. The memory locations where the data bits are maintained are physical locations having specific electrical, magnetic, optical, or organic characteristics corresponding to or representing the data bits. Representative embodiments are not limited to the above-described platforms or CPUs, and it should be understood that other platforms and CPUs may support the provided methods.

[0179] Data bits may also be maintained on a computer-readable medium, including magnetic disks, optical disks, and any other volatile (e.g., random access memory (“RAM”)) or non-volatile (e.g., read-only memory (“ROM”)) mass storage systems readable by a CPU. The computer-readable medium may include cooperative or interconnected computer-readable media that exist exclusively on a processing system or are distributed among a plurality of interconnected processing systems that may be local or remote to the processing system. Representative embodiments are not limited to the above-described memories, and it should be understood that other platforms and memories may support the described methods.

[0180] In an exemplary embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile body, network element, and / or any other computing device.

[0181] There is little distinction between the hardware implementation and the software implementation of the system aspects. The use of hardware or software is generally (e.g., although not always, in certain contexts the choice between hardware and software can be important) a design choice representing a cost - efficiency trade - off. There can be various vehicles (e.g., hardware, software, and / or firmware) that can potentially affect the processes and / or systems and / or other technologies described herein, and the preferred vehicle can vary depending on the situation in which the process and / or system and / or other technology is deployed. For example, if the implementer determines that speed and accuracy are of utmost importance, the implementer can choose primarily a hardware and / or firmware vehicle. If flexibility is of utmost importance, the implementer can choose primarily a software implementation. Alternatively, the implementer may choose some combination of hardware, software, and / or firmware.

[0182] In the foregoing detailed description, various embodiments of devices and / or processes have been shown through the use of block diagrams, flowcharts, and / or examples. As long as such block diagrams, flowcharts, and / or examples include one or more functions and / or operations, it will be understood by those skilled in the art that each function and / or each operation in such block diagrams, flowcharts, or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware, or substantially any combination thereof. Suitable processors include, by way of example, general - purpose processors, dedicated processors, conventional processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, application - specific integrated circuits (ASICs), application - specific standard products (ASSPs), field - programmable gate array (FPGA) circuits, any other type of integrated circuit (IC), and / or state machines.

[0183] While the features and elements have been provided in a particular combination above, those skilled in the art will understand that each feature or each element can be used alone or in any combination with other features and elements. This disclosure is not limited in terms of the specific embodiments described in this application, and these embodiments are intended as examples of various aspects. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the spirit and scope of the present invention. Any element, operation, or instruction used in the description of this application should not be construed as important or essential to the present invention unless explicitly presented as such. In addition to those listed in this specification, functionally equivalent methods and devices within the scope of this disclosure will be apparent to those skilled in the art from the above description. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the terms of the appended claims, and is limited together with the full scope of equivalents to which such claims are entitled. It should be understood that this disclosure is not limited to a particular method or system.

[0184] It should also be understood that the terms used in this specification are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in this specification and when referred to herein, "station" and its abbreviation "STA", "user equipment" and its abbreviation "UE" may mean, or include, (i) a wireless transmit and / or receive unit (WTRU) such as the described infrastructure, (ii) any of some embodiments of a WTRU such as the described infrastructure, (iii) a wireless-capable and / or wire-capable (e.g., tetherable) device configured to have some or all of the structure and functionality of a WTRU as illustrated (e.g., such as the described infrastructure), (iii) a wireless-capable and / or wire-capable device configured to have less structure and functionality than all of a WTRU such as the described (e.g., such as the described infrastructure), or (iv) otherwise. Details of exemplary WTRUs that may represent any of the UEs listed herein are provided below with respect to FIGS. 1A-1D.

[0185] In certain representative embodiments, some portions of the subject matter described herein may be implemented via application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integrated formats. However, some aspects of the embodiments disclosed herein may be equivalently implemented in an integrated circuit as one or more computer programs operating on one or more computers (e.g., as one or more programs operating on one or more computer systems), as one or more programs operating on one or more processors (e.g., as one or more programs operating on one or more microprocessors), as firmware, or in substantially any combination thereof, and it will be recognized by those of skill in the art that designing the circuitry and / or writing code for the software and / or firmware is within the scope of the skill of those of skill in the art in light of this disclosure. Further, it will be understood by those of skill in the art that the mechanisms of the subject matter described herein may be distributed as various forms of program products, and that the exemplary embodiments of the subject matter described herein apply regardless of the particular type of signal carrying medium used to actually carry out the distribution. Examples of signal carrying media include recordable media such as floppy disks, hard disk drives, CDs, DVDs, digital tapes, computer memories, and transmission media such as digital and / or analog communication media (e.g., optical fiber cables, waveguides, wired communication links, wireless communication links, etc.), but are not limited thereto.

[0186] The subject matter described in this specification may, in some cases, depict different components that are included within or connected to different other components. It should be understood that such illustrated architectures are merely examples, and that many other architectures that achieve the same functionality may actually be implemented. Conceptually, any arrangement of components for achieving the same functionality is effectively "associated" so that the desired functionality can be achieved. Thus, any two components combined in this specification to achieve a particular function can be viewed as "associated" with each other such that the desired function is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated can also be considered to be "operably connected" or "operably coupled" to each other to achieve the desired function, and any two components that can be so associated can also be considered to be "operably couplable" to each other to achieve the desired function. Specific examples of operably couplable include, but are not limited to, components that are physically fittable and / or physically interact, and / or wirelessly interact and / or wirelessly interact, and / or logically interact and / or logically interactable components.

[0187] With respect to the use of substantially any plural and / or singular terms in this specification, those skilled in the art can convert from plural to singular and / or from singular to plural as appropriate to the context and / or application. In this specification, various singular / plural permutations may be explicitly recited for clarity purposes.

[0188] Generally, the terms used in this specification, and especially in the appended claims (e.g., the body of the appended claims), will be understood by those of ordinary skill in the art to generally be intended as "open" terms (e.g., the term "comprising" should be interpreted to mean "including but not limited to", the term "having" should be interpreted to mean "having at least", and the term "including" should be interpreted to mean "including but not limited to"). Further, where a specific number of introductions of a claim is intended, such intent will be expressly recited in the claim, and where no such recitation is present, it will be understood by those of ordinary skill in the art that no such intent exists. For example, if only one item is intended, the term "single" or similar words may be used. To assist understanding, the following appended claims and / or the description in this specification may include the use of introductory phrases such as "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be interpreted as meaning that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim that includes such introduced claim recitation to embodiments including only one such recitation, even if the same claim includes both an introductory phrase such as "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be interpreted to mean "at least one" or "one or more"). The same holds for the use of definite articles used to introduce claim recitations. Further, even where a specific number of introductions of a claim is expressly recited, it will be recognized by those of ordinary skill in the art that such recitation should be interpreted to mean at least the recited number (e.g., a simple recitation of "two recitations" without other modifiers means at least two recitations, or two or more recitations).

[0189] Furthermore, when notations similar to “at least one of A, B, and C” are used, generally, such a structure is intended to mean what a person skilled in the art would understand from such notations (e.g., “a system having at least one of A, B, and C” includes a system having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, and C together, but is not limited thereto). When notations similar to “at least one of A, B, or C” are used, generally, such a structure is intended to mean what a person skilled in the art would understand from such notations (e.g., “a system having at least one of A, B, or C” includes a system having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, and C together, but is not limited thereto). It will be further understood by those skilled in the art that substantially any discrete word and / or phrase presenting two or more alternative terms in any of the description, claims, or drawings is to be understood as contemplating the possibility of including one of the terms, any of the terms, or both terms. For example, the phrase “A or B” is to be understood as including the possibility of “A” or “B” or “A and B”. Further, as used herein, the term “any of” following a list of items and / or a list of categories of items is intended to include “any of”, “any combination of”, “any plurality of”, and / or “any combination of a plurality of” the items and / or categories of items, individually or in combination with other items and / or other categories of items. Further, as used herein, the terms “set / group” or “group” are intended to include any number of items including zero. Further, as used herein, the term “number” is intended to include any number including zero.

[0190] In addition, when a feature or aspect of the present disclosure is described from the perspective of a Markush group, those skilled in the art will recognize that the present disclosure is thereby also described from the perspective of any individual member or subgroup of members of the Markush group.

[0191] As will be understood by those skilled in the art, for all purposes, such as from the perspective of providing a written description, all ranges disclosed in this specification also include any possible sub-ranges and combinations of those sub-ranges. Any recited range can be readily recognized as enabling, by way of illustration, the same range to be decomposed into at least equal halves, thirds, quarters, fifths, tenths, and so on. As a non-limiting example, each range described in this specification can be readily decomposed into a lower third, a middle third, and an upper third, and so on. Also, as will be understood by those skilled in the art, all words such as "up to", "at least", "greater than", "less than", etc. mean a range that includes the recited number and can further be decomposed into sub-ranges as described above. Finally, as will be understood by those skilled in the art, a range includes individual elements. Thus, for example, a group having 1 to 3 cells refers to a group having 1, 2, or 3 cells. Similarly, a group having 1 to 5 cells refers to a group having 1, 2, 3, 4, or 5 cells, and so on.

[0192] Furthermore, the claims should not be read as being limited to the order provided or the elements provided, unless specifically so recited. Additionally, in any claim, the use of the term "means for" is not intended to invoke 35 U.S.C. § 112, paragraph 6, or the means-plus-function claim format, and no claim without the term "means for" is so intended.

[0193] A radio frequency transceiver can be implemented for use in a wireless transmit-receive unit (WTRU), user equipment (UE), terminal, base station, mobility management entity (MME) or Evolved Packet Core (EPC), or any host computer, using a processor associated with software. The WTRU may be used in conjunction with hardware and / or software implemented modules such as, for example, Software Defined Radio (SDR), and may also be implemented in other components such as a camera, a video camera module, a videophone, a speakerphone, a vibrating device, a speaker, a microphone, a television transceiver, a hands-free headset, a keyboard, a Bluetooth® module, a frequency modulation (FM) radio unit, a Near Field Communication (NFC) module, an LCD display unit, an organic light emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and / or a wireless local area network (WLAN) or Ultra Wide Band (UWB) module.

[0194] Although the invention has been described in the context of a communication system, it is contemplated that the system may be implemented in software on a microprocessor / general purpose computer (not shown). In certain embodiments, one or more of the functions of the various components may be implemented in software that controls a general purpose computer.

[0195] In addition, although the invention has been illustrated and described herein with reference to particular embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made within the scope of the claims and their equivalents and without departing from the spirit of the invention.

[0196] Throughout this disclosure, one of ordinary skill in the art will understand that certain representative embodiments can be used alternatively or in combination with other representative embodiments.

[0197] Features and elements are described above in certain combinations, but one of ordinary skill in the art will understand that each feature or element can be used alone or in any combination with other features and elements. Further, 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 processor. Examples of non-transitory computer-readable storage media include, but are not limited to, magnetic media such as read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, internal hard disks, and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A radio frequency transceiver for use in a WRTU, UE, terminal, base station, RNC, or any host computer can be implemented using a processor associated with software.

[0198] Furthermore, in the above embodiments, other devices including a processing platform, computing system, controller, and processor are described. These devices can include at least one central processing unit ("CPU") and memory. According to the convention of those of ordinary skill in the art in the technical field of computer programming, references to operations, and symbolic representations of operations or instructions can be implemented by various CPUs and memories. Such operations and operations or instructions are sometimes referred to as "executed," "executed by a computer," or "executed by a CPU."

[0199] Those skilled in the art will understand that operations and symbolically represented operations or instructions involve the manipulation of electrical signals by a CPU. An electrical system represents data bits that can cause a resultant conversion or reduction of electrical signals, maintains the data bits in memory locations of a memory system, thereby restructuring or otherwise changing the operation of the CPU and the processing of other signals. The memory locations where the data bits are maintained are physical locations having specific electrical, magnetic, optical, or organic characteristics corresponding to or representing the data bits.

[0200] Data bits can also be maintained on a computer-readable medium, including magnetic disks, optical disks, and any other volatile (e.g., random access memory ("RAM")) or non-volatile (e.g., read-only memory ("ROM")) mass storage systems readable by a CPU. The computer-readable medium can include cooperative or interconnected computer-readable media that exist exclusively on a processing system or are distributed among multiple interconnected processing systems that can be local or remote to the processing system. Representative embodiments are not limited to the memory described above, and it is understood that other platforms and memories can support the described methods.

[0201] Suitable processors include, by way of example, general-purpose processors, dedicated processors, conventional processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), field-programmable gate array (FPGA) circuits, any other type of integrated circuit (IC), and / or state machines.

[0202] Although the present invention has been described with respect to a communication system, it is contemplated that the system may be implemented in software on a microprocessor / general purpose computer (not shown). In certain embodiments, one or more of the functions of the various components may be implemented in software that controls a general purpose computer.

[0203] In addition, although the present invention has been illustrated and described herein with reference to specific embodiments, the present invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope of the claims and their equivalents and without departing from the spirit of the invention.

Claims

1. A method implemented in a wireless transmit / receive unit (WTRU) for wireless communication, comprising: receiving configuration information of one or more reference signal (RS) resource sets, wherein at least one of the one or more RS resource sets is associated with a set of slot offsets and slot offset deltas; receiving downlink control information (DCI) indicating an RS request indicating the at least one of the one or more RS resource sets; determining a slot offset delta from the set of slot offset deltas associated with the at least one RS resource set; determining a slot for transmitting the RS based on the slot offset delta and the slot offset associated with the at least one RS resource set; determining an RS configuration from a set of RS configurations for RS transmission; transmitting the RS in the determined slot.

2. The method of claim 1, wherein the RS configuration is determined from the set of RS configurations for RS transmission based on any one of: 1) a search space or CORESET in which the DCI is received; 2) a DCI format; 3) an indication in the DCI; or 4) a radio network temporary identifier (RNTI) used to scramble a cyclic redundancy check (CRC) for the DCI.

3. A method implemented in a wireless transmit / receive unit (WTRU) for wireless communication, comprising: receiving configuration information of one or more reference signal (RS) resource sets, wherein at least one of the one or more RS resource sets is associated with a set of slot offsets and slot offset deltas, and the one or more RS resource sets include one or more sounding reference signal (SRS) resource sets; receiving downlink control information (DCI) indicating an RS request indicating the at least one of the one or more RS resource sets; determining a slot offset delta from the set of slot offset deltas associated with the at least one RS resource set; Determining a slot for transmitting the RS based on the slot offset delta and the slot offset associated with the at least one RS resource set; Transmitting the RS in the determined slot, a method. **Claim 4** A wireless transmit / receive unit (WTRU) for wireless communication, comprising a circuit including a processor, a transmitter, a receiver, and a memory, Receiving configuration information of one or more reference signal (RS) resource sets, wherein at least one RS resource set of the one or more RS resource sets is associated with a set of a slot offset and a slot offset delta, Receiving downlink control information (DCI) indicating an RS request indicating the at least one RS resource set among the one or more RS resource sets, Determining a slot offset delta from the set of slot offset deltas associated with the at least one RS resource set, Determining a slot for transmitting the RS based on the slot offset delta and the slot offset associated with the at least one RS resource set, Determining an RS configuration from a set of RS configurations for RS transmission, A WTRU configured to transmit the RS in the determined slot. **Claim 5** The RS configuration is determined from the set of RS configurations for the RS transmission based on any one of 1) a search space or CORESET in which the DCI is received, 2) a DCI format, 3) an indication in the DCI, or 4) a radio network temporary identifier (RNTI) used to scramble a cyclic redundancy check (CRC) for the DCI, according to the WTRU of claim 4. **Claim 6** A wireless transmit / receive unit (WTRU) for wireless communication, comprising a circuit including a processor, a transmitter, a receiver, and a memory, Receiving configuration information of one or more reference signal (RS) resource sets, wherein at least one RS resource set of the one or more RS resource sets is associated with a set of a slot offset and a slot offset delta, and the one or more RS resource sets include one or more sounding reference signal (SRS) resource sets, Receive downlink control information (DCI) indicating an RS request indicating the at least one RS resource set among the one or more RS resource sets, Determine a slot offset delta from the set of slot offset deltas associated with the at least one RS resource set, Determine a slot for transmitting the RS based on the slot offset delta and the slot offset associated with the at least one RS resource set, A WTRU configured to transmit the RS in the determined slot.

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