METHODS AND APPARATUS FOR TRANSMISSION OF FLEXIBLE APERIODIC SOUND REFERENCE SIGNALS (SRS)

Abstract

Methods, apparatus, and systems are provided for flexible aperiodic reference signal (RS) transmissions.For example, a method implemented in a wireless transmit / receive unit (WTRU) for wireless communications comprises receiving configuration information from one or more sound reference signal (SRS) resource sets, each SRS resource set from one or more SRS resource sets being associated with a slot offset and a set of slot offset deltas; receiving downlink control information (DCI) indicating an SRS request, the SRS request indicating an SRS resource set from one or more SRS resource sets; determining an SRS configuration from a set of SRS configurations for SRS transmissions; determining a slot to transmit an SRS based on the determined SRS configuration; and transmitting, in the determined slot, the SRS using resources from the indicated SRS resource set.

Description

METHODS AND APPARATUS FOR TRANSMISSION OF FLEXIBLE APERIODIC SOUND REFERENCE SIGNALS (SRS) FIELD OF INVENTION The modalities described herein generally relate to communication networks, both wireless and / or wired. For example, one or more of the modalities described herein relate to methods and apparatus for the transmission of flexible aperiodic sound reference signals (SRS). BACKGROUND OF THE INVENTION In one embodiment, a method implemented in a wireless transmit / receive unit (WTRU) for wireless communications comprises receiving configuration information from one or more sound reference signal (SRS) resource sets, and each SRS resource set from one or more SRS resource sets is associated with a slot offset and a set of slot offset deltas, receiving downlink control information (DCI) indicating an SRS request, and the SRS request indicating an SRS resource set from one or more SRS resource sets, determining an SRS configuration from a set of SRS configurations for SRS transmissions, and determining a slot to transmit an SRS based on the configuration. Ref. 341883 Determine the SRS, and transmit, in the determined slot, the SRS using resources from the specified SRS resource pool. BRIEF DESCRIPTION OF THE FIGURES A more detailed understanding can be obtained from the detailed description below, provided as an example along with the figures accompanying this document. The figures, like the detailed description, are examples. As such, the figures and the detailed description should not be considered limiting, and other equally effective examples are possible and probable. Furthermore, similar reference numbers in the figures indicate similar elements, and where: Figure 1A is a system diagram illustrating an illustrative communications system in which one or more of the described modalities can be implemented; Figure IB is a system diagram illustrating an illustrative wireless transmit / receive unit (WTRU) that can be used within the communications system illustrated in Figure 1A according to a modality; Figure IC is a system diagram illustrating an illustrative radio access network (RAN) and an illustrative core network (CN) that can be used within the communications system illustrated in Figure 1A according to a modality; Figure ID is a system diagram that illustrates another Illustrative RAN and another illustrative CN that can be used within the communications system illustrated in Figure 1A according to a modality; Figure 2 is a slot diagram illustrating the operation of an aperiodic SRS transmission, according to one or more modes; Figure 3 is a diagram illustrating an example of an SRS configuration structure, according to one or more modalities; Figure 4 is a slot diagram illustrating an example of delta displacement indication(s) by means of a Medium Access Control (MAC) control element (CE) or CE MAC, according to one or more modalities; Figure 5 is a diagram illustrating an example of a time pattern configured by SRS, according to one or more modalities; Figure 6 is a diagram illustrating an example of using indication(s) for SRS transmission(s) in a first uplink slot of a later channel occupancy time (COT), according to one or more modes; Figure 7 is a diagram illustrating an example of an SRS transmission in a COT acquired from the WTRU, according to one or more modalities; Figure 8 is a slot diagram illustrating an example of a two-stage DCI indicating mechanism(s) for SRS transmission(s), according to one or more modalities; Figure 9 is a slot diagram illustrating an example of a mode determination mechanism for aperiodic SRS transmission(s), according to one or more modes; and Figures 10A and 10B are slot diagrams illustrating an example of mechanisms using slot format indication(s) for aperiodic SRS transmission(s), according to one or more modes. DETAILED DESCRIPTION OF THE INVENTION In the following detailed description, numerous specific details are set forth to provide a complete understanding of the modalities and / or examples described herein. However, it is understood that such modalities and examples may be implemented without some or all of the specific details set forth herein. In other cases, known methods, procedures, components, and circuits have not been described in detail so as not to alter the following description. Furthermore, modalities and examples not specifically described herein may be implemented instead of, or in combination with, the modalities and other examples described or otherwise provided explicitly, implicitly, and / or inherently (collectively provided) herein. Although various modalities are described and / or claimed herein, in which an apparatus, system, device, etc.and / or any element thereof carries out an operation, process, algorithm, function, etc. and / or any portion thereof, it shall be understood that any modality described and / or claimed in the present description assumes that any apparatus, system, device, etc. and / or any element thereof is configured to carry out any operation, process, algorithm, function, etc. and / or any portion thereof, it shall be understood that any modality described and / or claimed in the present description assumes that any apparatus, system, device, etc. and / or any element thereof is configured to carry out any operation, process, algorithm, function, etc. and / or any portion thereof. Communications networks and devices The methods, devices, and systems described herein are well-suited for communications involving both wired and wireless networks. Wired networks are widely known. An overview of various types of wireless devices and infrastructure is provided with reference to Figures 1A–1D, where various network elements can be used, operated, arranged in accordance with, and / or adapted and / or configured for the methods, devices, and systems described herein. Figure 1A is a diagram illustrating an illustrative communication system 100 in which one or more of the described modes can be implemented. The communication system 100 can be a multi-access system that provides content, such as voice, data, video, messaging, broadcasting, etc., to multiple wireless network users. The communication system 100 can allow multiple wireless network users access to such content through the distribution of system resources, including wireless network bandwidth.For example, 100 communication systems may use one or more access methods per channel, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SCFDMA), zero-tail single-word DFT spread OFDM (ZT UW DTS-s OFDM), single-word OFDM (UW-OFDM), resource-lock filter OFDM, filter bank multi-carrier (FBMC), and the like. As shown in Figure 1A, the communications system 100 may include wireless transmit / receive units (the WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110 and other 112 networks, although it will be appreciated that the described modalities encompass any number of WTRUs, base stations, networks and / or network elements. Each WTRU 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment.For example, WTRU 102a, 102b, 102c, 102d, any of which may be referred to as a station and / or STA, may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a mobile or fixed subscriber unit, a subscription-based unit, an electronic locator, a cell phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a Mi-Fi or access point device, an Internet of Things (IoT) device, a watch or other wearable device, a virtual reality headset (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g.a robot and / or other wireless devices operating in industrial and / or automated processing chain contexts), a consumer electronic device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRU 102a, 102b, 102c and 102d may be referred to interchangeably as UE. Communication systems 100 may also include a 114a base station and / or a 114b base station. Each of the 114a, 114b base stations may be any type of device configured to wirelessly interconnect with at least one of the 102a, 102b, 102c, 102d WTRUs to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the other 112 networks. By way of example, the 114a, 114b base stations may be a Base Transceiver Station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, a New Radio (NR) Node B, a Site Controller, an Access Point (AP), a Wireless Router, and the like. Although base stations 114a, 114b are illustrated, each as a single element, it will be appreciated that base stations 114a, 114b can include any number of interconnected base stations and / or network elements.Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may have licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographic area, which may be relatively fixed or may change over time. Furthermore, the cell may be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors.Therefore, in one mode, base station 114a can include three transceivers, e.g., one for each cell sector. In one mode, base station 114a can use multiple-input multiple-output (MIMO) technology and can use multiple transceivers for each cell sector. For example, beamforming can be used to transmit and / or receive signals in desired spatial directions. Base stations 114a, 114b can communicate with one or more of WTRUs 102a, 102b, 102c, 102d via an air interface 116 which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, microwave, infrared (IR) light, ultraviolet (UV) light, visible light, etc.). The air interface 116 can be established using any suitable radio access technology (RAT). More specifically, as mentioned earlier, the 100 communications system can be a multiple access system and can use one or more access schemes per channel, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, base station 114a in RAN 104 / 113 and WRTUs 102a, 102b, and 102c can implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish air interface 115 / 116 / 117 using Wideband CDMA (WCDMA). WCDMA can include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or HSPA+.HSPA may include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​Uplink (HSUPA) Packet Access. In one mode, base station 114a and WTRUs 102a, 102b, 102c can implement a radio technology, such as UMTS Evolved Terrestrial Radio Access (E-UTRA), which can establish air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro). In one mode, base station 114a and WTRUs 102a, 102b, 102c can implement a radio technology, such as NR radio access, which can establish air interface 116 using New Radio (NR). In one configuration, base station 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can jointly implement LTE radio access and NR radio access, for example, using dual connectivity (DC) principles. Therefore, the air interface used by WTRUs 102a, 102b, and 102c can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB). In other modes, the 114a base station and the 102a, 102b, 102c WTRUs can implement radio technologies such as IEEE 802.11 (e.g., Wireless Fidelity (WiFi)), IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, 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), and the like. The base station 114b in Figure 1A can be a wireless router, a home Node B, a home eNode B, or an access point, for example, and can use any suitable RAT to facilitate wireless connectivity in a localized area, such as a workplace, home, vehicle, campus, industrial facility, air corridor (e.g., for use by drones), highway, and the like. In one mode, the base station 114b and the WTRU 102c and 102d can implement a radio technology, such as IEEE 802.11, to establish a wireless local area network (WLAN). In another mode, the base station 114b and the WTRU 102c and 102d can implement a radio technology, such as IEEE 802.15, to establish a wireless personal area network (WPAN). Even in another mode, the 114b base station and the 102c, 102d WTRUs can use a cell-based RAT (e.g.(WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. As shown in Figure 1A, base station 114b can have a direct connection to Internet 110. Therefore, base station 114b may not need to have Internet 110 access via CN 106 / 115. RAN 104 / 113 may be in communication with the 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 the WTRU 102a, 102b, 102c, and 102d. Data may have varying Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. CN 106 / 115 may 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 observed that RAN 104 / 113 and / or CN 106 / 115 can be in direct or indirect communication with other RANs that use the same RAT as RAN 104 / 113 or a different RAT. For example, in addition to being connected to RAN 104 / 113, which may use NR radio technology, CN 106 / 115 may also be in communication with another RAN (not shown) that uses GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology. CN 106 / 115 can also serve as a gateway for WTRU 102a, 102b, 102c, and 102d to access PSTN 108, the Internet 110, and / or other 112 networks. PSTN 108 may include circuit-switched telephone networks providing Ordinary Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) within the TCP / IP Internet protocol suite. 112 networks may include wired and / or wireless communication networks owned and / or operated by other service providers.For example, 112 networks may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 / 113 or a different RAT. Some or all of the WTRU 102a, 102b, 102c, and 102d units in the 100 communications system may include multimode capabilities (e.g., WTRU 102a, 102b, 102c, and 102d units may include multiple transceivers to communicate with different wireless networks over separate wireless links). For example, the WTRU 102c unit shown in Figure 1A may be configured to communicate with base station 114a, which may use cellular-based radio technology, and with base station 114b, which may use IEEE 802.12 radio technology. Figure IB is a system diagram that illustrates a Illustrative WTRU 102. As shown in Figure IB, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keyboard 126, a display / touch panel 128, non-removable memory 130, removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any subcombination of the above elements while maintaining consistency with a modality. The processor 118 can be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, application-specific integrated circuits (ASICs), field-programmable gate array circuits (FPGAs), any other type of integrated circuit (IC), a state machine, and the like. The processor 118 can perform signal encoding, 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 the transceiver 120, which can be coupled to the transmit / receive element 122.Although Figure IB illustrates the processor 118 and transceiver 120 as separate components, it will be appreciated that the processor 118 and transceiver 120 can be integrated together in one electronic package or chip. Transmit / receive element 122 can be configured to transmit signals to, or receive signals from, a base station (e.g., base station 114a) via air interface 116. For example, in one mode, transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In another mode, transmit / receive element 122 can be a transmitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another mode, transmit / receive element 122 can be configured to transmit and / or receive both RF and light signals. It will be appreciated that transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals. Although the transmit / receive element 122 is illustrated in Figure IB as a single element, the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can use MIMO technology. Therefore, in one mode, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) to transmit and receive wireless signals across the air interface 116. Transceiver 120 can be configured to modulate the signals transmitted by transmit / receive element 122 and demodulate the signals received by transmit / receive element 122. As mentioned earlier, the WTRU 102 can have multimode capabilities. Therefore, transceiver 120 can include multiple transceivers to allow the WTRU 102 to communicate using multiple RATs, such as NR and IEEE 802.11, for example. The WTRU 102 processor 118 can be coupled to, and can receive user input data from, the speaker / microphone 124, the keyboard 126, and / or the display / touch panel 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit). The processor 118 can also send user data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. In addition, the processor 118 can access information from, and store data in, any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. Non-removable memory 130 can include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device.Removable memory 132 may include a Subscriber Identity Module (SIM) card, a memory card, a Secure Digital Memory (SD) card, and the like. In other modes, the processor 118 may access information from, and store data in, memory that is not physically located in the WTRU 102, such as in a server or home computer (not shown). The processor 118 can receive power from the power supply 134, and can be configured to distribute and / or control power to the other components in the WTRU 102. The power supply 134 can be any device suitable for supplying power to the WTRU 102. For example, the power supply 134 can include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like. In addition, the 118 processor can also be coupled to the 136 GPS chipset, which can be configured to provide location information (e.g., longitude and latitude) relative to the WTRU 102's current location. Besides, or instead of, the information from the 136 GPS chipset, the WTRU 102 can receive location information via the 116 air interface from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the periodicity of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 can acquire location information by any suitable location determination method as long as it maintains coherence with a mode. In addition, the processor 118 can be coupled with other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired and / or wireless connectivity. For example, peripherals 138 may include an accelerometer, a digital compass, a satellite transceiver, a digital camera (for stills and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, an 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 monitoring device, and the like.Peripherals 138 may include one or more sensors; the sensors may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor. The WTRU 102 may include a full-duplex radio for which the transmission and reception of some or all of the signals (e.g., those associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may occur at the same time and / or be simultaneous. The full-duplex radio may include an interference handling unit 139 to substantially reduce and / or eliminate self-interference through either hardware (e.g., a shutter) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In one mode, the WTRU 102 may include a half-duplex radio for the transmission and reception of some or all of the signals (e.g., those associated with particular subframes for both the UL (e.g., for transmission) or the downlink (e.g., for reception)). Figure 1C is a system diagram illustrating RAN 104 and CN 106 in one mode. As mentioned earlier, RAN 104 can use E-UTRA radio technology to communicate with WTRU 102a, 102b, and 102c over air interface 116. RAN 104 can also communicate with CN 106. RAN 104 can include eNodes-B 160a, 160b, and 160c, although it should be noted that RAN 104 can include any number of eNodes-B as long as it maintains coherence with one mode. eNodes-B 160a, 160b, and 160c can each include one or more transceivers for communicating with WTRU 102a, 102b, and 102c over air interface 116. In one mode, eNodes-B 160a, 160b, and 160c can implement MIMO technology. Therefore, eNode-B 160a, for example, can use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, WTRU 102a. Each of the eNodes B 160a, 160b, 160c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, and the like. As shown in Figure 1C, the eNodes-B 160a, 160b, 160c can communicate with each other via an X2 interface. The CN 106 shown in Figure 1C may include a Mobility Management Entity (MME) 162, a Service Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. Although each of the above elements is illustrated as part of CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator. The MME 162 can connect to each of the eNode B 160a, 160b, and 160c in RAN 104 via an SI interface and can serve as a control node. For example, the MME 162 can be responsible for authenticating users of WTRU 102a, 102b, and 102c, activating / deactivating carriers, selecting a particular service gateway during the initial mating of WTRU 102a, 102b, and 102c, and similar tasks. The MME 162 can also provide a control plane function for switching between RAN 104 and other RANs (not shown) that use other radio technologies, such as GSM and / or WCDMA. SGW 164 can connect to each of the eNode-Bs 160a, 160b, and 160c on RAN 104 via the SI interface. Generally, SGW 164 can direct and forward user data packets to / from WTRUs 102a, 102b, and 102c. SGW 164 can perform other functions, such as anchoring user planes during inter-eNode-B transfers, triggering searches when DL data is available for WTRUs 102a, 102b, and 102c, managing and storing contexts for WTRUs 102a, 102b, and 102c, and similar tasks. The SGW 164 can connect to the PGW 166, which can provide the WTRU 102a, 102b, 102c with access to packet-switched networks, such as Internet 110, to facilitate communication between the WTRU 102a, 102b, 102c and IP-enabled devices. CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRU 102a, 102b, and 102c with access to circuit-switched networks, such as PSTN 108, to facilitate communication between WTRU 102a, 102b, and 102c and traditional landline communication devices. For example, CN 106 can include, or communicate with, an IP gateway (e.g., an IP Media Subsystem (IMS) server) that serves as an interface between CN 106 and PSTN 108. Additionally, CN 106 can provide WTRU 102a, 102b, and 102c with access to other 112 networks, which may include other wired and / or wireless networks owned and / or operated by other service providers. Although the WTRU is described in Figures 1A-1D as a wireless terminal, it is envisaged that in certain representative modalities such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network. In representative modalities, the other 112 network can be a WLAN. A WLAN in Basic Service Set (BSS) infrastructure mode can have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access to, or an interface with, a distribution system (DS) or other type of wired / wireless network that carries traffic to and / or from the BSS. Traffic to the STAs originating from outside the BSS can arrive through the AP and be delivered to the STAs. Traffic originating from the STAs and destined for locations outside the BSS can be sent to the AP for delivery to the respective destinations. Traffic between STAs within the BSS can be sent through the AP; for example, the source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within a BSS can be considered and / or referred to as peer-to-peer traffic.Peer-to-peer traffic can be sent between (e.g., directly between) the source and destination STAs using a Direct Link System (DLS) configuration. In certain representative configurations, the DLS can use either 802.111 DLS or a tunneled 802.111 DLS (TDLS). A WLAN using an independent BSS mode (IBSS) may not have an access point (AP), and the STAs (e.g., all STAs) within or using the IBSS can communicate directly with each other. The IBSS communication mode may sometimes be referred to in this description as an ad hoc communication mode. When using 802.11ac infrastructure mode or a similar operating mode, the AP can transmit a beacon on a fixed channel, such as a primary channel. The primary channel can have a fixed width (e.g., 20 MHz bandwidth) or a width dynamically configured through signaling. The primary channel can be the operating channel of the BSS and can be used by the STAs to establish a connection with the AP. In certain representative modes, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example, in 802.11 systems. For CSMA / CA, the STAs (e.g., each STA), including the AP, can detect the primary channel. If the primary channel is detected and / or determined to be occupied by a particular STA, that STA can take over. An STA (e.g., a single station) can transmit at any given time on a given BSS. High-performance STAs (HTs) can use a 40 MHz wide channel for communications, for example, through a combination of the primary 20 MHz channel with an adjacent or non-adjacent 20 MHz channel to form a 40 MHz wide channel. Very high-throughput STAs (VHTs) can support channels 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide. 40 MHz and / or 80 MHz channels can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, can be passed through a segment analyzer that can split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can then be performed on each stream separately. The currents can be mapped over the two 80 MHz channels, and the data can be transmitted by a transmitting STA.At the receiving STA receiver, the operation described above for the 80+80 configuration can be reversed and the combined data can be sent to the media access control (MAC). Operating modes below 1 GHz are supported by 802.11af and 802.11ah. The channel bandwidths and carriers used in 802.11af and 802.11ah are reduced compared to those used in 802.11η and 802.11ac. 802.11af supports bandwidths of 5 MHz, 10 MHz, and 20 MHz in the TV white space (TVWS) spectrum, while 802.11ah supports bandwidths of 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz using a spectrum different from the TVWS. In one representative scenario, 802.11ah can support meter / machine control communications, such as MTC devices, in a macro-coverage area. MTC devices may have certain capabilities, for example, limited capabilities that include support for (e.g., support only for) certain bandwidths and / or limited bandwidths. MTC devices may include a battery with a battery life above a certain threshold (e.g.(to maintain a very long battery life). WLAN systems, which can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as the primary channel. The primary channel can have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The primary channel bandwidth can be configured and / or limited by the STA, of all the STAs operating in a BSS, that supports the smallest bandwidth operating mode. In the 802.11ah example, the primary channel can be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1 MHz mode, even if the AP and other STAs in the BSS support operating modes of 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidths. Carrier sensing and / or network allocation vector (NAV) settings may depend on the primary channel state.If the primary channel is occupied, for example, because an STA (which only supports a 1 MHz operating mode) is transmitting to the AP, all available frequency bands may be considered occupied even though a majority of the frequency bands remain free and may be available. In the United States, the available frequency bands that can be used by 802.11ah are between 902 MHz and 928 MHz. In Korea, the available frequency bands are between 917.5 MHz and 923.5 MHz. In Japan, the available frequency bands are between 916.5 MHz and 927.5 MHz. The total bandwidth available for 802.11ah is from 6 MHz to 26 MHz, depending on the country code. Figure ID is a system diagram illustrating RAN 113 and CN 115 in one mode. As mentioned previously, RAN 113 can use NR radio technology to communicate with WTRU 102a, 102b, and 102c over air interface 116. RAN 113 can also communicate with CN 115. RAN 113 can include gNB 180a, 180b, and 180c, although it should be noted that RAN 113 can include any number of gNBs while maintaining mode coherence. Each gNB 180a, 180b, and 180c can include one or more transceivers for communicating with WTRU 102a, 102b, and 102c over air interface 116. In one mode, gNB 180a, 180b, and 180c can implement MIMO technology. For example, gNB 180a and 180b can use beamforming to transmit signals to and / or receive signals from gNB 180a, 180b, and 180c. Therefore, the gNB 180a, for example, can use multiple antennas to transmit wireless signals to the WTRU 102a, and / or receive wireless signals from it. In one mode, the gNB 180a, 180b, and 180c can implement carrier aggregation technology. For example, the gNB 180a can transmit multiple component carriers to the WTRU 102a (not shown).A subset of these component carriers may be in the unlicensed spectrum, while the remaining component carriers may be in the licensed spectrum. In one mode, gNB 180a, 180b, and 180c can implement coordinated multipoint (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c). WTRU 102a, 102b, and 102c can communicate with gNB 180a, 180b, and 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or the OFDM subcarrier spacing can vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. WTRU 102a, 102b, and 102c can communicate with gNB 180a, 180b, and 180c using subframes or intervals of IVIA / I time transmission (TTI) of various lengths or scalable lengths (e.g., with a variable number of OFDM symbols and / or variable lengths of absolute time). The gNB 180a, 180b, and 180c can be configured to communicate with the WTRU 102a, 102b, and 102c in either a standalone or non-standalone configuration. In the standalone configuration, the WTRU 102a, 102b, and 102c can communicate with the gNB 180a, 180b, and 180c without having access to other RANs (e.g., such as the eNodes B 160a, 160b, and 160c). In the standalone configuration, the WTRU 102a, 102b, and 102c can use one or more of the gNB 180a, 180b, and 180c as a mobility anchor point. In standalone configuration, WTRU 102a, 102b, and 102c can communicate with gNB 180a, 180b, and 180c using signals in an unlicensed band. In non-standalone configuration, WTRU 102a, 102b, and 102c can communicate / connect with gNB 180a, 180b, and 180c and simultaneously communicate / connect with other RANs, such as eNodes B 160a, 160b, and 160c.For example, WTRU 102a, 102b, and 102c can implement DC principles to communicate with one or more gNB 180a, 180b, and 180c and one or more eNodes B 160a, 160b, and 160c substantially simultaneously. In the non-standalone configuration, the eNodes B 160a, 160b, and 160c can serve as a mobility anchor for the WTRU 102a, 102b, and 102c, and the gNB 180a, 180b, and 180c can provide [the necessary support]. ML / Ί additional coverage and / or performance for the maintenance of the WTRU 102a, 102b, 102c. Each of the gNB 180a, 180b, and 180c units can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in the UL and / or DL, support network splits, dual connectivity, interconnection between NR and E-UTRA, routing user plane data to the User Plane (UPE) function 184a and 184b, routing control plane information to the Access Control and Mobility (AME) function 182a and 182b, and the like. As shown in Figure ID, the gNB 180a, 180b, and 180c units can communicate with each other via an Xn interface. The CN 115 shown in Figure ID may include at least one AME 182a, 182b, at least one UPE 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the above elements is illustrated as part of CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator. The AME 182a, 182b can connect to one or more of the gNB 180a, 180b, 180c on RAN 113 via an N2 interface and can serve as a control node. For example, the AMF AMF 182a and 182b may be responsible for authenticating users of WTRU 102a, 102b, and 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a and 183b, managing the registration area, terminating NAS signaling, handling mobility, and similar tasks. Network slicing may be used by AMF 182a and 182b to customize CN compatibility with WTRU 102a, 102b, and 102c based on the types of services used by WTRU 102a, 102b, and 102c. For example, different network cutoffs can be established for different use cases, such as services based on ultra-reliable low-latency access (URLLC), services based on enhanced and massive mobile broadband access (eMBB), services for access to machine-type communication (MTC), and / or the like.The AMF 182 can provide a control plane function to switch between RAN 113 and other RANs (not shown) that use other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi. SMF 183a, 183b can connect to AMF 182a, 182b on CN 115 via an N11 interface. SMF 183a, 183b can also connect to UPF 184a, 184b on CN 115 via an N4 interface. SMF 183a, 183b can select and control UPF 184a, 184b and configure traffic routing through UPF 184a, 184b. SMF 183a, 183b can perform other functions, such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy and QoS enforcement, providing downlink data notifications, and the like. A PDU session type can be IP-based, non-IP-based, Ethernet-based, and so on. The UPF 184a, 184b can connect to one or more of the gNB 180a, 180b, 180c on RAN 113 via an N3 interface, which can provide the WTRU 102a, 102b, 102c with access to packet-switched networks, such as Internet 110, to facilitate communication between the WTRU 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b can perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multihoqar PDU sessions, managing user plane QoS, buffering downlink packets, providing mobility tethering, and the like. CN 115 can facilitate communication with other networks. For example, CN 115 can include, or communicate with, an IP gateway (e.g., an IP Media Subsystem (IMS) server) that serves as an interface between CN 115 and PSTN 108. Additionally, CN 115 can provide WTRU 102a, 102b, and 102c with access to other 112 networks, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one mode, WTRU 102a, 102b, 102c can connect to a local data network (DN) 185a, 185b through UPE 184a, 184b via interface N3 to UPE 184a, 184b and interface N6 between UPE 184a, 184b and DN 185a, 185b. In view of Figures 1A-1D, and the corresponding description of Figures 1A-1D, one or more, or all, of the functions described herein with respect to one or more of: WTRU 102a-d, base station 114a-b, eNode B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AME 182a-b, UPE 184a-b, SMF 183a-b, DN 185a-b, and / or any other device or devices described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, emulation devices can be used to test other devices and / or to simulate network and / or WTRU functions. Emulation devices can be designed to perform one or more tests on other devices in a laboratory and / or carrier network environment. For example, one or more emulation devices can perform one or more, or all, of the functions while being fully or partially deployed as part of a wired and / or wireless communications network to test other devices within that network. Alternatively, one or more emulation devices can perform one or more, or all, of the functions while being temporarily deployed as part of a wired and / or wireless communications network. The emulation device can be directly coupled to another device for testing purposes and / or can perform tests using wireless over-the-air communications. The emulation device(s) may perform one or more, or even all, of the functions while not being deployed as part of a wired and / or wireless communications network. For example, the emulation devices may be used in a test scenario in a test lab and / or an undeployed wired and / or wireless communications network (e.g., for testing) to perform tests on one or more components. The emulation device(s) may be test equipment. The emulation devices may use direct RF coupling and / or wireless communications via RF circuits (e.g., which may include one or more antennas) to transmit and / or receive data. Sound Reference Signal (SRS) transmission The Sound Reference Signal (SRS) is primarily used for uplink channel measurement. SRS transmission can also be used to aid in estimating downlink Channel State Information (CSI) for partial or fully reciprocal channels. Furthermore, SRS can be used for beam management, where SRS transmission through different SRS resources supports beam selection by a network (e.g., a gNB). Therefore, enabling a dynamic and flexible sound procedure with adequate capacity and coverage is essential for a MIMO system (e.g., improving MIMO performance). In the new 5G (NR) radio (e.g., NR Version 16), a WTRU (e.g., UE) can 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 capacity of the WTRU (e.g., UE). An SRS resource set can be configured for different applications (e.g., usage) such as beam management, codebook, no codebook, or antenna switching. In some examples, the time-domain behavior of the SRS resource configuration is indicated by a top-layer resourceType parameter. The time-domain behavior can be configured as periodic, semi-persistent, and / or aperiodic. In NR (e.g., NR Version 16), a WTRU cannot have different time-domain behavior (e.g., periodic and semi-persistent), and in some cases, the WTRU cannot have different periodicities for SRS resources within the same set of SRS resources. In some examples, if a WTRU is activated to transmit SRS over the same symbol(s), an aperiodic SRS has higher transmission priority than a periodic SRS and / or a semi-persistent SRS. In some cases, an aperiodic SRS has priority over the physical uplink control channel (PUCCH) if the aperiodic SRS is activated to be transmitted on the same symbol that is also used for the PUCCH, except when the PUCCH carries a hybrid automatic repeat request (HARQ) (e.g., a HARQ-ACK or NACK), a link recovery request, and / or a scheduling request (SR). In semi-persistent SRS operation, a WTRU can be activated / deactivated by downlink control information (DCI) to start / stop SRS transmission(s). However, the impact of misdetecting the deactivation signal can be significant, as a WTRU may continue sending SRS, potentially resulting in unnecessary interference and battery drain for the WTRU. Figure 2 illustrates an illustrative operation of an aperiodic SRS transmission. For aperiodic SRS configuration, a WTRU (e.g., a UE) can receive a set of upper-layer parameters for SRS-ResourceSet, including, for example: slotOffset, SRS-ResourceSetld, AperiodicSRS-ResourceTrigger, and / or AperiodicSRSResourceTriggerList. An aperiodic SRS transmission can be triggered by a WTRU-specific DCI, a common group DCI, or an uplink DCI. An associated SRS request field (e.g., a two-bit SRS request field) in DCI format 0_1, 1_1, 0_2 (if the SRS request field is present), and 1_2 (if the SRS request field is present) can trigger the corresponding SRS transmission. Based on 3GPP standards (e.g., 3GPP TS 38.214, Version 16), if a WTRU receives an aperiodic SRS that activates a DCI in slot n, the WTRU transmits the aperiodic SRS on each of the activated SRS resource sets in the slot: slot,displacement,PDCCHlvranur a,displacement,SRS 2^displacement,PDCCH 2^^esP^azam^enio¿RS I 2μ5K5 I , / f (k) = n· —---- + k + where k is configured via an upper layer parameter slotOffset for each activated SRS resource set, and the configuration of k is based on the respective subcarrier spacing of the activated SRS transmission. In some current implementations, when a WTRU receives a DCI triggering an aperiodic SRS, the slot-level offset for sending the aperiodic SRS depends on `slotOffset`, a higher-layer parameter configured using Radio Resource Control (RRC) signaling. Relying on a configured RRC value to determine a transmission slot for the aperiodic SRS imposes some limitations on the performance of a wireless communication system. For example, if the specified slot offset occurs in a downlink (DL) slot, the intended SRS transmission will be ignored, and the scheduler must retry another opportunity.In another example, in a multi-user MIMO (MU-MIMO) system, multiple users can be activated to engage in a simultaneous aperiodic SRS transmission to provide the scheduler with an accurate estimate of channel and interference. However, activating all WTRUs at the same time (which involves the transmission of multiple simultaneous DCIs) can cause congestion for the downlink control channel or DL ​​transmissions. By allowing the slot-level offset of the aperiodic SRS to be configured by Layer 1 (L1), a potential collision between the SRS transmission and other transmissions can be avoided. As such, an aperiodic SRS could be transmitted more flexibly and reliably with less overhead and latency. Therefore, to further increase the flexibility of the aperiodic SRS, dynamic control of SRS transmissions is desired, for example, through enhanced SRS control that triggers offset(s). Two-stage displacement indication(s) In various configurations, a WTRU configured for aperiodic SRS transmission can determine a slot for aperiodic SRS transmission in two stages. For example, a WTRU can be configured or indicated with more than one set of information to determine the slot index for SRS transmission. - Delta displacement value configured by RRC In various modes, a WTRU can receive a first configuration (e.g., an SRS configuration) via RRC signaling that includes the slotOffset(k) value, and receive a second configuration (e.g., slotOffset_delta) via RRC signaling. The second configuration can contain one or more delta offset values ​​that can be used to correct the first set of configured RRC offset values ​​(e.g., slotOffset(k) received or determined from the first configuration). To enable aperiodic SRS transmission, a WTRU can receive a DCI or a Medium Access Control (MAC) control element (CE) that has a field (e.g., n bits) to indicate the slotOffset_delta, where each state of the DCI or MAC CE field can be used as an index to a specific configured delta offset value (Ak) in the configured slotOffset_delta.A WTRU can determine the slot index for aperiodic SRS transmission by combining the indicated slotOffset and slotOffset_delta values, e.g., k+Ak. Figure 3 illustrates an example of an SRS configuration structure in NR. As shown in Figure 3, the SRS configuration (e.g., the overall SRS configuration of RRC) can be divided into three different property levels, namely: SRS-Config, SRS-ResourceSet, and SRSResource, where high-level properties, behavior properties, and resource-level properties are defined, respectively. In one mode, a WTRU can be configured with slotOffset delta as part of SRS-Config. Therefore, the slotOffset_delta configuration can be applied to all SRS resource sets and / or SRS resources. In one mode, a WTRU can be configured with slotOffset_delta as part of slotOffset_delta. Therefore, the configured slotOffset delta can only be applied to SRS resources configured in that SRS resource set. Alternatively, a WTRU can be configured with slotOffset_delta as part of the SRS-Resource configuration. Therefore, the slotOffset_delta configuration can only be applied to a specific SRS resource within a set of SRS resources. In one mode, the delta offset value can be configured at one or more SRS configuration levels. For example, a WTRU might be configured with two delta offset values ​​set in SRS-ResourceSet and SRS-Resource. Therefore, the received DCI or CE MAC field can point to a specific combination of offset values ​​configured in SRS-ResourceSet and SRS-Resource. - Delta displacement value indicated by CE MAC In one mode, a WTRU can receive an initial configuration (e.g., an SRS configuration via RRC signaling) that includes the (k) slotOffset value, and receive a second configuration from a CE MAC (e.g., slotOffset delta) indicating one or more delta offset values. In some examples, the offset value indicated by a CE MAC may include or indicate one or more delta offset values. As shown in Figure 4, a WTRU can receive a CE MAC (containing slotOffset_delta) before or after (or in the same slot) the DCI activates an aperiodic SRS transmission. In one mode, one or more delta offset values, indicated by slotOffset_delta in a CE, The MAC address may be valid until it is updated (e.g., via the network, a programmer, or a gNB). In one mode, a WTRU can be configured with a time validity interval referencing the reception of a physical downlink control channel (PDCCH) (or DCI) that triggers an aperiodic SRS transmission. A WTRU can consider slotOffset_delta (indicated by a CE MAC), for example, only if the CE MAC is received within the time validity interval. In one example, a time validity interval can be defined by two integer values, where the first defines the start of the interval, and the second defines the end of the interval, with respect to slot n where the PDCCH triggering the aperiodic SRS is received. In one mode, a WTRU can receive an explicit indication (e.g., a DCI indicator) or an implicit indication (e.g., a mode of operation to consider), or it can alternatively ignore the slotOffset_delta indicated by a CE MAC. In various modes, when a WTRU receives slotOffset_delta via a CE MAC containing more than one delta offset value, the WTRU can receive a DCI with an m-bit field to enable aperiodic SRS transmission. Each state of the DCI field can be used as an index to a specific configured delta offset value (Δλ) in slotOffset_delta. The WTRU can determine the slot index for aperiodic SRS transmission by combining the specified slotOffset and slotOffset_delta values, e.g., k+fk. In various modes, when a WTRU receives slotOffset_delta via a CE MAC containing a unique delta offset value, the WTRU can receive a DCI to activate aperiodic SRS transmission. The WTRU can determine the slot index for aperiodic SRS transmission by directly combining the slotOffset and slotOffset_delta values, for example, k+Δλ. In one mode, a WTRU can receive a common group DCI to activate an aperiodic SRS transmission simultaneously for multiple users (e.g., multiple WTRUs), where each WTRU in the group can receive a respective CE MAC containing a different slotOffset_delta to indicate a corresponding delta offset value to adjust the configured slotOffset of the individual RRC. - Value of the delta displacement indicated implicitly In one mode, a WTRU can receive a first configuration (e.g., an SRS configuration via RRC signaling) that includes the slotOffset(k) value, and implicitly receive or determine a second configuration. The second configuration can include one or more slotOffset_delta parameters indicating the delta offset values ​​to correct the first configured offset value (e.g., a value such as slotOffset received from an SRS configuration via RRC signaling). In one example, a WTRU can receive a DCI encoded with a Radio Network Temporary Identifier (RNTI) that corresponds directly to a slotOffset_delta value, or via an index to a set of slotOffset_delta values ​​configured by the RRC as described herein (e.g., the previous section, RRC-Configured Delta Offset Value).In another example, a WTRU can be configured with more than one search space and / or CORESET and each can correspond directly to a slotOffset delta or via an index to a set of slotOffset_delta configured by RRC as described in this description (e.g., the previous section RRC-configured delta offset value). Unique INN indication In various forms, SRS resource sets may be referred to interchangeably as SRS resources. - Improved SRS configuration For aperiodic SRS configuration, a WTRU can receive a set of upper-layer parameters for RSResourceSet, including any of: slotOffset, srsResourceSetld, AperiodicSRS-ResourceTrigger, and AperiodicSRSResourceTriggerList. An aperiodic SRS transmission can be triggered by a WTRU-specific DCI, a common group DCI, or an uplink DCI. In various configurations, a WTRU with its codebook or noncodebook usage set can be configured with more than one SRS resource set (e.g., multiple SRS resource sets or SRS resources), and each SRS resource set can be configured with a different slot offset value. In one configuration, an SRS resource set indicator (e.g., indicated by a DCI or CE MAC) can specify which SRS resource set will be used for aperiodic SRS transmission. In various configurations, a WTRU with its codebook or noncodebook usage set can be configured with more than two SRS resource sets, and each SRS resource set can be configured with a different slotOffset_resource value. A respective configured slotOffset_resource can be used either as a replacement for the slotOffset configured in SRSResourceSet or as a correction to the configured slotOffset. - Reuse of existing PCI formats In various modes, a WTRU can determine one or more slot offsets for SRS resource sets based on one or more of the following. In one mode, a WTRU can determine one or more slot offsets for SRS resource sets based on one or more dedicated DCI formats: a) For example, the WTRU can dynamically determine slot offsets for SRS resources 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). The one or more dedicated DCI formats may comprise one or more of the following: i) A non-SUL / SUL indicator: (1) In one mode, if the WTRU is configured with a cell with multiple uplinks (ULs), the WTRU can determine one or more ULs from the multiple ULs based on an indicator. For example, if the WTRU receives a first indicator, it can determine a first uplink (e.g., a non-complementary uplink). If the WTRU receives a second indicator, it can determine a second uplink (e.g., a complementary uplink). ii) An SRS application: (1) In one mode, the WTRU can determine the transmission of SRS 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 mode, the WTRU can determine the transmission of SRS based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU may not transmit any SRS resource sets. If the WTRU receives a second indication based on the indicator, the WTRU may transmit a first set of SRS resource sets. If the WTRU receives a third indication based on the indicator, the WTRU may transmit a second set of SRS resource sets. iii)Transmission Power Control Command (TPC): (1) In one mode, the WTRU can determine the transmission power of SRS resource pools based on an indicator. For example, if the WTRU receives a first indication based on the indicator, the WTRU can determine a first transmission power of SRS resource pools. If the WTRU receives a second indication based on the indicator, the WTRU can determine a second transmission power of SRS resource pools. iv) Slot offset for SRS resource sets (e.g., one slot offset for all activated SRS resource sets): (1) In one mode, the WTRU can determine a slot offset for activated SRS resource sets (e.g., via 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 displacement may be based on one or more of the following: (a) predefined slot offsets for indicated values; (b) slot offsets preconfigured for indicated values; and (c) explicit indication of slot offsets. v) Slot offsets for SRS resource sets (e.g., a slot offset specific to an SRS resource set of activated SRS resource sets): (1) In one mode, the WTRU can determine one or more slot offsets for activated SRS resource sets (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 shifts may be equal to the number of SRS resource sets activated. (b) If the number of slot offsets is greater than the number of activated SRS resource sets, the WTRU may apply slot offsets to all activated SRS resource sets or activated SRS resource sets that are not associated with slot offsets based on one or more of the following: (i) do not apply a slot offset; (ii) apply a predetermined slot offset; (iii) apply an average value of indicated slot displacements; and (iv) apply a first / last slot displacement of indicated slot displacements. (c) If the number of slot offsets is less than the number of activated SRS resource sets, the WTRU may indicate specific values ​​(e.g., 0 or 1) for one or more indicators that are not associated with activated SRS resource sets. (2) The determination of slot displacements may be based on one or more of the following: (a) predefined slot offsets for indicated values; (b) slot offsets preconfigured for indicated values; and (c) explicit indication of slot offsets. (3) The WTRU can apply a given set of slot offsets based on a given slot offset (e.g., delta-offset). For example, if the WTRU receives a first slot offset for activated SRS resource sets (e.g., one slot offset for all activated SRS resource sets) and a second slot offset for a first SRS resource set of simultaneously activated SRS resource sets, the WTRU can apply the first slot offset to all activated SRS resource sets and the second slot offset to the first SRS resource set based on the first slot offset. In one mode, a WTRU can determine one or more slot offsets for SRS resource sets based on one or more existing DCI formats: a) For example, the WTRU can dynamically determine slot offsets for SRS resources 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 may determine one or more existing DCI formats as a slot offset indication DCI based on one or more of the following: i) RNTI. (1) In one mode, if a DCI is coded with a first RNTI (e.g., SRS-RNTI), the WTRU can determine the DCI as comprising one or more SRS slot shift indications. If the DCI is coded with a second RNTI (e.g., C-RNTI, CS-RNTI, etc.), the WTRU can determine the DCI as having another purpose (e.g., PDSCH / PUSCH programming, configured lease activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). ii) HARQ process number. (1) In one mode, if the HARQ process number is set to specific first bits (e.g., all 0s), the WTRU can determine the DCI as a DCI comprising one or more SRS slot indications. If the HARQ process number is not set to specific first bits, the WTRU can determine the DCI as a DCI for another purpose (e.g., PDSCH / PUSCH programming, configured lease activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). iii) Redundancy version. (1) In one mode, if the redundancy version is set on specific first bits (e.g., all 0s), the WTRU can determine the DCI as a DCI comprising one or more SRS slot indications. If the redundancy version is not set on specific first bits, the WTRU can determine the DCI as a DCI for another purpose (e.g., PDSCH / PUSCH programming, configured lease activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.) iv) Modulation and encoding scheme. (1) In one mode, if the modulation and encoding scheme is set on specific first bits (e.g., all 0s), the WTRU can determine the DCI as a DCI comprising one or more SRS slot indications. If the modulation and encoding scheme is not set on specific first bits, the WTRU can determine the DCI as a DCI for another purpose (e.g., PDSCH / PUSCH programming, configured lease activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). v) Frequency domain resource allocation. (1) In one mode, if the frequency domain resource allocation is set to specific first bits (e.g., all 0s), the WTRU can determine the DCI as a DCI comprising one or more SRS slot indications. If the frequency domain resource allocation is not set to specific first bits, the WTRU can determine the DCI as a DCI for another purpose (e.g., PDSCH / PUSCH programming, configured lease activation / release, semi-persistent CSI activation / deactivation, TPC command, etc.). c) If the WTRU determines a DCI as comprising one or more slot offset indications, one or more of the following fields may be used for the one or more slot offset indications: (1) frequency domain resource allocation; (2) time domain resource allocation: (3) downlink assignment index (e.g., 1st and / or 2nd); and (4) precoding information and number of layers. d) The one or more slot displacement indications may comprise one or more of the following: (i) Slot offset for SRS resource sets (e.g., one slot offset for all activated SRS resource sets) (1) In one mode, the WTRU can determine a slot offset for activated SRS resource sets (e.g., via 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 displacement may be based on one or more of the following: (a) predefined slot offsets for indicated values; (b) slot offsets preconfigured for indicated values; and (c) explicit indication of slot offsets. (ii) Slot offsets for SRS resource sets (e.g., a specific slot offset for an SRS resource set from activated SRS resource sets) (1) In one mode, the WTRU can determine one or more slot offsets for activated SRS resource sets (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 can be equal to the number of SRS resource sets activated. (b) If the number of slot offsets is greater than the number of activated SRS resource sets, the WTRU may apply slot offsets to all activated SRS resource sets or activated SRS resource sets that are not associated with slot offsets based on one or more of the following: 1. Do not apply a slot offset; 2. Apply a predetermined slot offset; 3. Apply an average value of the indicated slot displacements; and 4. Apply a first / last slot offset of the indicated slot offsets. (c) If the number of slot offsets is less than the number of activated SRS resource sets, the WTRU may indicate specific values ​​(e.g., 0 or 1) for indicators that are not associated with activated SRS resource sets. (2) The determination of slot displacements may be based on one or more of the following: (a) predefined slot offsets for indicated values; (b) slot offsets preconfigured for indicated values; and (c) explicit indication of slot offsets. (3) The WTRU can apply a given set of slot offsets based on a given slot offset (e.g., delta-offset). For example, if the WTRU receives a first slot offset for activated SRS resource sets (e.g., one slot offset for all activated SRS resource sets) and a second slot offset for a first SRS resource set of simultaneously activated SRS resource sets, the WTRU can apply the first slot offset to all activated SRS resource sets and the second slot offset to the first SRS resource set based on the first slot offset. Advanced slot indication In various configurations, a WTRU can receive an indication to transmit SRS in a time slot belonging to a set of possible SRS time slots configured by higher layers. These solutions can allow the network to enable SRS transmission from many UEs in the same slot without excessive overhead on DCI constraint or time scheduling. - Time pattern configured in SRS The WTRU can be configured with at least one set of time-domain resources for the potential transmission of SRS. Each such set can be referred to as an SRS-configured time pattern. Each SRS-configured time pattern can be associated with an index. For example, an SRS-configured time pattern might consist of a set of time symbols or a set of time slots defined by a period and offset in terms of slots and / or symbols. In another example, an SRS-configured time pattern might be characterized by a bitmap of a certain length and a time reference, such as the start of a symbol, slot, subframe, and / or frame identified by a symbol number, slot number, subframe number, or frame number, respectively. The pattern can then be defined by the bitmap starting at the time reference and subsequently repeating.Figure 5 shows an example of a configured time pattern. The parameters that define an SRS-configured time pattern can be configured by RRC or be predefined. In one mode, a set of SRS-configured time patterns can be configured separately from SRS resources. Alternatively, at least one SRS-configured time pattern can be configured as part of the SRS resource configuration. For example, at least one SRS-configured time pattern can be configured as a new resource type. - SRS property variable per transmission event In various modes, a WTRU can be configured with an SRS-configured time pattern, and each SRS transmission opportunity in the SRS-configured time pattern can 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. In one mode, a WTRU can be configured with more than one type of SRS configuration. For example, a WTRU can be configured with two or more (different) types of SRS configuration(s); 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 timing pattern. In one mode, when each SRS transmission opportunity in the SRS-configured time pattern is associated with a different SRS resource set configuration, the resource type can be assumed to be aperiodic. For example, a WTRU might assume or be configured with different uses (e.g., beamManagement, codebook, nonCodebook, and / or antennaSwitching) for each SRS transmission opportunity. For instance, a WTRU might 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 a respective SRS resource set configuration), a WTRU might use a respective (or different) SRS resource set configuration according to the respective configured SRS resource set for the SRS transmission opportunity in the configured pattern (e.g.,, the timing pattern configured by SRS). In one mode, when each SRS transmission opportunity in the SRS-configured time pattern is configured with the same set of SRS resources, but is associated with a different SRS resource configuration, a WTRU can use a different SRS resource property for each respective SRS transmission opportunity. In one example, a WTRU can be configured with more than one type of SRS resource set configuration. For instance, a WTRU can be configured with two or more (different) types of SRS resource set configurations: one type can be used for normal SRS operation, and a second type can be used when the WTRU is configured with an SRS timing pattern. In another example, a WTRU (configured with an SRS timing pattern) can be configured with more than one SRS resource set configuration for each respective SRS resource set. In one mode, each SRS transmission opportunity can be configured to have a different SRS resource configuration to employ a different transmission property. For example, a WTRU might use a different number of SRS ports in each transmission opportunity. In another example, to support multiple TRPs or increase transmission diversity, a WTRU might use a different spatialRelationInfo (e.g., spatial filter, beam) in each transmission opportunity. Additionally or alternatively, a WTRU might use a different offset or cyclic sequence in each transmission event to randomize potential interference(s). - Activation of the time pattern configured by SRS In various configurations, a time pattern configured by SRS can be in an on or off state. The WTRU can determine that the resource pool for potential SRS transmission consists only of the set of SRS-configured time patterns that are currently on. These solutions can allow a network to modify SRS transmission opportunities more dynamically for each UE and, therefore, modify MU-MIMO pairing candidates more efficiently. The WTRU can determine the state upon receiving RRC, MAC, or DCI signaling. For example, the WTRU can receive a MAC control element indicating which of the at least one SRS-configured time pattern is active, e.g., using a bitmap or at least an index for an SRS-configured time pattern. In one mode, the WTRU can determine a single active SRS-configured time pattern based on an index received from an RRC, MAC, or DCI signal and determine that any other SRS-configured time pattern is inactive. After the RRC reconfigures a set of SRS-configured time patterns, the WTRU can determine the initial state of each pattern as either active or inactive, either explicitly from the RRC signaling or implicitly (e.g., all active, all inactive, or only the first one active).After the bandwidth portion change, the WTRU can implicitly determine that the state of each pattern is either on or off. - SRS time pattern set to activated In various modes, a WTRU can 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 apply to a specific set of SRS-configured time patterns, such as an activated set of SRS-configured time patterns or a set explicitly included in the indication. In this case, the WTRU can determine that the set of SRS-configured time patterns may be in an activated state. The WTRU may subsequently transmit SRS a number of times for an SRS-configured time pattern based on the condition that it is in an activated state. The transmission may occur after the reception of a second indication or another event (e.g., the start of a COT), as described below.After SRS transmission for a configured time pattern, the WTRU can determine that the pattern is in an inactive state. The WTRU can also determine that a pattern is in an inactive state by changing the bandwidth portion or by the expiration of a timer initiated when the pattern is set to an active state. After the reconfiguration of a set of SRS-configured time patterns by RRC, or the activation of a set of SRS-configured time patterns, the WTRU can determine whether the initial state of each pattern is active or inactive. - Activation of SRS transmissions The WTRU can transmit the SRS on at least one occasion defined by at least one time pattern configured by SRS based on the following. In one mode, the WTRU can transmit on all occasions defined by the union of time patterns configured by SRS, or alternatively by the union of time patterns configured by SRS activated. In one mode, the WTRU can transmit on a subset of occasions by a time pattern configured by SRS upon receiving a DCI, after the start of a COT, or after successful channel access. The following may be indicated in the DCI, signaled by a MAC (e.g., an EC MAC) or an RRC message, or may be predefined: 1) a set of time patterns configured by SRS for which the SRS is transmitted; 2) a number of times for which SRS is transmitted for each pattern or set of patterns; and / or 3) the first time for which SRS is transmitted for each pattern or set of patterns. For example, such a time may be the Nth time after a certain number of S symbols following the last symbol of the PDCCH for which the DCI is decoded, where N and S may be predefined or indicated in the DCI. In various modes, the set of time patterns configured by SRS can be restricted to the subset of activated patterns and / or activated patterns. Instruction to transmit within a channel occupancy time (COT) In various modes, a WTRU can receive an indication to transmit an SRS in a slot of a current or future COT. For example, as shown in Figure 6, the WTRU can receive an indication via the DCI or CE MAC to transmit an SRS in the next UL resources of a current COT. In another example, the WTRU can receive an indication to transmit an SRS in a specific UL resource (e.g., the first UL resource) of a later or future COT. In this example, the WTRU may not need to receive an additional indication to transmit an SRS and can do so after determining or being indicated that the later or future COT has started. The WTRU may receive an indication that it can transmit an SRS on a specific (e.g., first) UL resource of a COT acquired from the UE. In such a case, a WTRU can transmit an SRS on a UL resource upon successfully acquiring the channel and initiating a COT acquired from the UE. In some cases, as shown in Figure 7, the gNB may be aware of the specific time when the WTRU will attempt to acquire the channel and initiate a COT (e.g., if the gNB has granted specific resources on which the WTRU can attempt to acquire the channel). In other cases, the WTRU may autonomously determine when to acquire the channel based on whether it has any data to transmit (e.g., on configured grant resources). Therefore, the WTRU may indicate to the gNB when a transmission includes a previously activated SRS. For example, the WTRU may receive an instruction to transmit an SRS on a specific UL resource of a future COT acquired from the UE.The WTRU can only attempt to acquire a COT when it has data to transmit in a configured lease. The WTRU can indicate to the gNB whether the COT acquired from the WTRU includes an SRS transmission. The WTRU can indicate to the gNB the presence of the SRS in at least one of: a standalone transmission, the configured lease UCI (CG-UCI), a PUCCH transmission, or implicitly through an SRS parameter. In one mode, upon receiving a network indication (e.g., a gNB) to transmit an SRS, the WTRU may attempt to acquire the channel on the next appropriately synchronized CG resource, regardless of whether the WTRU has data to transmit. Therefore, the WTRU can only transmit the SRS on the CG resource if it successfully acquires the channel. In one mode, a WTRU can be configured with SRS transmission opportunities as defined above (e.g., a time pattern configured by SRS). Such opportunities can occur periodically and can be defined with specific time instances (and possibly specific frequency locations). Upon receiving an indication to transmit an SRS on a future UL resource, the WTRU can transmit the SRS on the next SRS transmission opportunity. The WTRU can determine the appropriate SRS transmission opportunity in which to transmit the SRS as one that satisfies the offset indicated by the gNB. For example, the WTRU can determine to transmit the SRS on the first SRS transmission opportunity that occurs after the time it received the indication plus the indicated offset time.In another example, the WTRU can determine the transmission of SRS on an SRS transmission opportunity that occurs within the period initiated by the time it received the indication and ends by the time indicated by the offset. - Intra-WTRU coordination for transmitting SRS In various modes, a WTRU can acquire a COT (Control of Technology) and determine that the WTRU has resources to transmit SRS (System Reduction Signal) and that the WTRU is required to transmit SRS. The WTRU can then transmit a WTRU-to-WTRU (or UE-to-UE) indication that an upcoming SRS transmission resource will be used for SRS transmission, for example, before transmitting SRS. Other UEs can listen for such a transmission from a neighboring UE. After receiving a UE-to-UE indication, other UEs can transmit SRS on the same resources. This can enable multi-UE SRS transmission, potentially to support MU-MIMO (Multi-Uniform Multi-Instance Transmission). - LBT for SRS transmission activated In various modes, a WTRU can only use one channel to transmit SRS. In such cases, the WTRU may not need to perform a channel access (e.g., listen before you speak (LBT)) before transmitting SRS. In other cases, if the WTRU has data to transmit over resources that are adjacent to the SRS resources, the WTRU may perform a channel access (e.g., LBT). The selection of the type of LBT to perform may depend on at least one of the following: the presence of data, the type of data, the timing of the UL transmission relative to the preceding DL transmission (e.g., interval), or an indication received by the WTRU. - SRS transmission indication In various modes, a WTRU can receive an indication to transmit an SRS on a current or subsequent COT. Such an indication can be received by the DCI or CE MAC. The indication can reuse other transmissions on the control channel. For example, the WTRU can receive the indication to transmit an SRS on a DCI used to indicate that a COT is active. For example, a GC-PDCCH indicating an active COT can also be used to instruct the WTRU to transmit an SRS (possibly with a time offset). The time offset can be determined as a function of the COT timing. - Multiple time shifts In various modes, an indication of SRS transmission may include or map multiple time offsets. The WTRU can determine which moment offset as a function of at least one of: If a channel is acquired for the intended SRS transmission time (e.g., if there is an active COT), in this example, the WTRU can transmit SRS using the first time offset for which the channel is available for transmission. A parameter of the active COT. For example, if the WTRU acquired a first set of unlicensed sub-bands for a COT, the WTRU can use a first time offset for SRS transmission. If the WTRU acquires a second set of unlicensed sub-bands for a COT, the WTRU can use a second time offset for SRS transmission. The type of data that the WTRU needs to transmit (e.g. e.g., as a function of the content of its regulator). For example, higher priority data can be associated with a first time offset and lower priority data can be associated with a second time offset. If the WTRU has any data to transmit; and the priority of the SRS transmission. For example, different SRS transmissions can be assigned to different priorities. Two-stage PCI indication In various configurations, a WTRU can transmit SRS based on the reception of an SRS configuration trigger and (e.g., combined with) an SRS transmission trigger. In some examples, a two-stage DCI indication mechanism may involve using an SRS configuration trigger and an SRS transmission trigger on different downlink control channels (e.g., multiple DCIs or PDCCHs) for dynamic aperiodic SRS control and SRS transmissions. In some cases, the two-stage DCI indication mechanism can reduce PDCCH traffic overhead. Figure 8 shows an example of a two-stage DCI indication mechanism. In this example, a WTRU can receive an SRS configuration trigger on a first DCI (e.g., a WTRU-specific DCI). The WTRU can then receive an SRS transmission trigger on a second DCI (e.g., a common group DCI). Each DCI can be received on a corresponding PDCCH. A PDCCH can be received in a UE-specific search space or a common search space (SS). In one example, the SRS configuration trigger can be received on a WTRU-specific SS, and the SRS transmission trigger can be received on a common SS. The WTRU can be configured with an RNTI (e.g., a UE-specific or group RNTI) that can be used for (e.g., specifically for) the SRS transmission trigger. The WTRU can be configured with an RNTI (e.g., a UE-specific or group RNTI) that can be used for (e.g., specifically for) the SRS configuration trigger. The cyclic redundancy check (CRC) of a DCI can be encoded with an RNTI described herein. The WTRU can use the RNTI to receive the DCI (e.g., using the RNTI to successfully decode the DCI). In another example, a WTRU can receive one trigger on a CE MAC and another trigger on a DCI. For example, the WTRU might receive an SRS configuration trigger on a CE MAC. The WTRU might also receive an SRS transmission trigger on a DCI. Alternatively, the WTRU might receive each trigger on a corresponding CE MAC (e.g., different CE MACs). A WTRU can be configured with one or more resource sets that can be used for SRS transmission. A resource set can include one or more frequency and / or time resources (e.g., a frequency and / or time resource pattern). A frequency resource can be, or include, one or more resource elements (REs), resource blocks (RBs), or physical resource blocks (PRBs). The configuration of a resource set can identify frequency resources (e.g., frequency locations) for SRS transmission and / or time locations for SRS transmission. A time location can include, for example, a starting symbol, a number of symbols, which symbols within a time duration (such as a slot), a number of slots, a pattern of symbols and / or slots, and the like. In various modalities, a resource set (e.g., SRS resource set) and a resource set (e.g., SRS resources) may be used interchangeably in this description. In various modes, an SRS configuration trigger can identify one or more of the configured sets of SRS resources that can be used for SRS transmission. By identifying an SRS resource set, the trigger can (e.g., through the resource set configuration) identify time and / or frequency resources for SRS transmission. The identified resources can be in one or more slots. In one example, a resource set might have an associated slot offset (e.g., a resource set might be configured with a slot offset). An SRS configuration trigger might either instruct the user to use the associated slot offset (e.g., configured) or ignore the slot offset and, for example, wait for an SRS transmit trigger to transmit. If the SRS configuration trigger instructs the user to use the slot offset, the WTRU might transmit SRS on the specified resources in the slot indicated by the slot offset. The slot offset might indicate an offset of slots from the slot in which the PDCCH (or CE MAC) carrying the SRS configuration trigger is received. If the SRS configuration trigger instructs the user not to use the slot offset, the WTRU might not transmit SRS in response to receiving the SRS configuration trigger.The WTRU can transmit SRS in response to receiving an SRS transmit trigger, which can be received after the SRS setup trigger. In another example, a WTRU might not transmit SRS in response to receiving an SRS configuration trigger. The WTRU might understand that the trigger is for configuration and not transmission, for example, regardless of whether the SRS resource pool is configured or associated with a slot offset. In one example, an SRS resource set (e.g., an SRS resource set for use with a configuration trigger and a transmit trigger) may not be configured with a slot offset or may not have a slot offset associated with it. The WTRU may not transmit SRS in response to receiving the SRS configuration trigger. The WTRU may transmit SRS in response to receiving an SRS transmit trigger that may be received after the SRS configuration trigger. An SRS transmission trigger can specify one or more of the following: slot offset, number of slots, slot pattern, first slot, etc. An SRS transmission trigger can specify one or more SRS timing parameters. A timing parameter can be a slot, a slot offset, a starting slot, a number of slots, a slot pattern, a starting symbol, a number of symbols, a symbol pattern, etc. In one example, a WTRU can use an SRS configuration trigger to determine one or more (e.g., all) of the frequency-related parameters of an SRS transmission. The WTRU can use the SRS configuration trigger to determine at least some of the time-related parameters for the SRS transmission. The WTRU can use the SRS transmission trigger to determine at least some (e.g., some other) of the time-related SRS parameters. The value of a time-related parameter indicated by a transmit trigger can override the value of the time-related parameter indicated by a configuration trigger. For example, a WTRU might receive a first indication of a value for a time-related parameter via a configuration trigger. The WTRU might then receive a second indication of a value for the same time-related parameter via a transmit trigger. The WTRU might use the second value for the time-related parameter, for example, when determining when to transmit SRS. A WTRU can receive an SRS configuration trigger on or with a UL grant DCI or a DL grant DCI. A WTRU can receive an SRS transmission trigger on or with a UL grant DCI or a DL grant DCI. A WTRU may receive an SRS transmit trigger in a DCI that does not include or is not used for a UL grant or a DL grant. A WTRU may receive an SRS transmit trigger in a DCI that can be used to provide one or more of the following: an indicator of ML / Ί slot format (SFI), a channel occupancy time (COT) indication, and / or an SS switching indication. A COT indication can show the time remaining in a COT, for example, a COT acquired by a gNB. When the WTRU receives an SRS transmit trigger on a DCI that can be used to indicate SFI, COT, and / or SS switching, one or more of the indications for SFI, COT, and / or SS switching may or may not be present on the DCI. A WTRU can transmit SRS based on, or in response to, receiving an SRS transmit trigger. The WTRU can transmit SRS in relation to receiving the SRS transmit trigger. When a UE transmits SRS based on, or in response to, receiving an SRS transmit trigger, the WTRU can transmit SRS on resources in a slot indicated by a slot offset. The offset can be a number of slots away from the slot in which the PDCCH (or CE MAC) carrying the SRS transmit trigger is received. For example, the slot offset used by the WTRU can be indicated by the SRS transmit trigger. The slot offset can be indicated directly by the transmit trigger. For example, the slot offset can be included in the DCI or CE MAC provided by the transmit trigger.The slot offset can be indicated by an index or other indicator provided by the transmission actuator (e.g., by the DCI or CE MAC). The index or other indicator can point to a configured value from a set of configured values ​​for the slot offset. In one example, the slot offset that the WTRU uses might be a configured slot offset. For instance, the slot offset might be included in the SRS resource set configuration. The configuration trigger might specify the resource set. The transmission trigger might specify using the slot offset configured for the resource set (e.g., using it in relation to the transmission trigger). In another example, an SRS resource set might have a set of slot offsets configured for it. The transmission trigger might indicate which of the slot offsets to use. If only one slot offset is configured for a resource set, it might not need, use, or provide any indication of which one to use (e.g., when that resource set is specified). The WTRU can transmit SRS based on or using time-related resources, time-related parameters, and / or frequency resources specified by the combination of the configuration trigger and the transmission trigger. For example, the WTRU can transmit on the specified frequency resources. The WTRU can transmit on the symbols and slots based on the specified time-related parameters. The WTRU can transmit on one or more symbols, one or more slots, and / or according to a set or pattern of symbols and / or slots, for example, based on the specified time-related parameters. One or more WTRUs can receive individual SRS configuration triggers. One or more WTRUs can receive an SRS transmission trigger that can indicate a slot offset. The one or more void units can use the received slot offset and transmit SRS in the same slot. The one or more WTRUs can transmit SRS according to the resources and transmission parameters indicated by their respective configuration triggers. The SRS transmission parameters (e.g., whether or not they include other time and / or frequency resources) can be provided by the configuration trigger and / or the transmission trigger. The WTRU can transmit SRS according to the received transmission parameters. The transmission parameters specified by the transmission trigger can override the transmission parameters specified by the configuration trigger. An SRS resource set may include (e.g., can be configured with) a trigger mode indication. The trigger mode indication may specify when, or based on which trigger, to use one or more parameters, e.g., time-related parameters, to transmit SRS. The trigger mode may be indicated by the SRS resource set, which may be indicated by the SRS configuration trigger and / or the SRS transmission trigger received by the WTRU. For example, the trigger mode indication can specify whether to use the configured slot offset and / or one or more other parameters (e.g., time-related parameters) when a configuration trigger or a request indicating the resource set is received. A WTRU can use the trigger mode indication configured for the resource set to determine when (e.g., for or in response to which trigger or SRS request) to transmit SRS, e.g., according to the SRS resource set. For example, in the first trigger mode, the WTRU may transmit SRS in response to an SRS configuration trigger or an SRS request or trigger received on a UL or DL ​​grant. In the second trigger mode, the WTRU may not transmit SRS in response to an SRS configuration trigger or an SRS request or trigger received on a UL or DL ​​grant. In the second trigger mode, the WTRU may transmit SRS in response to an SRS transmission trigger, which may follow an SRS configuration trigger. In the second trigger mode, the WTRU may transmit SRS in response to an SRS transmission trigger or an SRS request or trigger not received on a UL or DL ​​grant. An SRS transmission may be considered a pending SRS transmission after receiving an SRS configuration trigger. An SRS configuration trigger or a pending SRS transmission may be canceled or may expire after an expiration time. For example, if a WTRU can receive an SRS configuration trigger in a first slot and does not receive a transmit trigger for more than a certain threshold number of slots, the WTRU can cancel the SRS transmit associated with the SRS configuration trigger. If the WTRU receives an SRS transmit trigger and does not have a pending SRS transmit (e.g., based on an unexpired SRS configuration trigger), the WTRU can ignore the SRS transmit trigger. A number of slots is one example. Another unit of time can be used for the expiration and / or threshold time, such as symbols, milliseconds, etc. A threshold can be configured in various ways. The configuration of a threshold can be included within the configuration of an SRS resource set. An SRS transmit trigger can be used when an SRS configuration trigger is received within a configured number of slots or a configured amount of time before the SRS transmit trigger is received. If a WTRU can receive an SRS transmit trigger (e.g., in a slot) and the WTRU has not received an SRS configuration trigger within a specified number of slots or within a specified amount or time interval before the SRS transmit trigger, the WTRU can ignore the SRS transmit trigger. For example, the WTRU can choose not to transmit SRS based on or in response to the transmit trigger. The number of slots or the amount of time can be a configured threshold number of slots or a configured threshold time interval. The number of slots or the amount of time can be a configured slot interval or a configured time interval. In various modes, a threshold (e.g., a slot or time threshold), slot interval, or time (e.g., in milliseconds) can be configured through at least one of the following: an SRS configuration trigger, an SRS transmission trigger, an SRS resource pool, and / or a separate setting. Time and amount of time can be used interchangeably. Selection mode for SU / MU-MIMO - Operating mode In various configurations, one or more operating modes can be used, defined, or configured for the aperiodic SRS trigger based on the determination of the aperiodic SRS trigger offset, where an aperiodic SRS trigger offset can be the 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 the triggered SRS resource and / or resource set. The aperiodic SRS trigger offset may hereafter be referred to interchangeably as SRS offset, slot offset, and / or trigger offset. In one operating mode, the SRS offset can be determined, used, or selected in a semi-static manner. For example, an SRS offset can be configured for each SRS resource set or SRS resource, and the associated SRS offset can be used, or it can be determined when an SRS resource set or an SRS resource is activated. In various modes, a set of SRS offset values ​​can be predefined or configured, and an SRS offset value within the set can be selected, used, or configured for an SRS resource set or an SRS resource. In one example, one or more SRS resources can be associated with an SRS resource set.An SRS offset can be configured or determined for an SRS resource set, and one or more SRS resources associated with the SRS resource set can use the SRS offset value configured for the associated SRS resource set. In one operating mode, the SRS offset can be determined, used, selected, or indicated dynamically. For example, the SRS offset for an activated SRS resource (or set of SRS resources) can be determined dynamically based on an indication. One or more of the following may apply: (1) The SRS offset indication can be signaled in associated control information (e.g., downlink control information or sidelink control information); and / or (2) the SRS offset indication can be a delta offset from the SRS offset configured for the SRS resource (or set of SRS resources). In one operating mode, the SRS offset can be implicitly determined based on one or more UE-specific system and / or parameters, where the UE-specific system and / or parameters can include at least one identity (e.g., cell-id, Ue-id, BWP-id), system configuration (e.g., subcarrier spacing, UL / DL TDD configuration, number of carriers, etc.), programming parameters (e.g., MCS, programmed bandwidth, configured or indicated DM-RS pattern, etc.) - Operating mode In one mode, an operating mode for an SRS trigger (e.g., SRS trigger mode) can be determined based on a used, selected, or determined uplink transmission mode. In several modes, an SRS trigger mode can be used to distinguish different uplink transmission modes, for example, between a single-user (SU) mode and a multi-user (MU) mode of uplink transmissions. In one example, an operating mode for an SRS trigger can be implemented using a scheme described herein, depending on an SU / MU operating mode. For example, an uplink transmission mode (e.g., the SU / MU uplink transmission mode) or an SRS trigger mode can be determined based on one or more of the following: • DCI format used for an SRS trigger. For example, a first SRS trigger mode can be used when an SRS transmission is triggered in a first DCI format (e.g., DCI format 0_1) and a second SRS trigger mode can be used when an SRS transmission is triggered in a second DCI format (e.g., DCI format 1 1). • Number of DM-RS CDM groups without data indicated. For example, if an SRS transmission is triggered in an IDC (e.g., IDC format 0_l) in which the number of DMRS CDM groups without data is greater than a threshold. The threshold may be different based on the type of DMRS, number of layers and / or number of code words. • DMRS type configured. For example, a first SRS trigger mode can be used when a first DMRS type (e.g., DMRS type 1) is configured for a UL transmission on the BWP; and a second SRS trigger mode can be used when a second DMRS type (e.g., DMRS type 2) is configured for a UE transmission on the BWP. • Configured DMRS density. For example, a first SRS trigger mode can be used when the DMRS density (e.g., time density) is less than a threshold; and a second SRS trigger mode can be used when the DMRS density is greater than or equal to the threshold. The DMRS density in this description may be the number of DMRS symbols in a slot. • Maximum number of MIMO layers configured. For example, a first SRS trigger mode can be used when the maximum number of MIMO layers configured for a BWP is less than a threshold; and a second SRS trigger mode can be used when the maximum number of MIMO layers configured for a BWP is equal to or greater than the threshold. In one mode, an SRS trigger mode can be determined based on a bandwidth portion (BWP) configuration. For example, a first SRS trigger mode can be configured, used, or determined for a first BWP, and a second SRS trigger mode can be configured, used, or determined for a second BWP. In some examples, an SRS trigger mode can be determined based on any of: an associated BWP-id, the number of SRS resources and / or SRS resource sets configured, the number of SRS antenna ports (e.g., maximum), and an SRS configuration for the BWP. In one mode, an SRS trigger mode can be determined based on the identity of the associated search space and / or CORESET. For example, the SRS trigger mode can be determined based on which search space and / or CORESET the WTRU received the SRS trigger from. If a UE received an SRS trigger in a first search space and / or CORESET (e.g., first search space identity or CORESET identity), the WTRU can use or determine a first SRS trigger mode; if the WTRU received an SRS trigger in a second search space and / or CORESET (e.g., second search space identity or CORESET identity), the WTRU can use or determine a second SRS trigger mode. In some cases, an SRS trigger mode can be configured for a search space and / or CORESET. In one scenario, an SRS trigger mode can be determined based on the number of bits configured for the SRS request field in a DCI. For example, if the number of bits for the SRS request field in a DCI is 2 or less, a first SRS trigger mode can be used or determined; otherwise, a second SRS trigger mode can be used. In some instances, when the SRS request bit field has more than 2 bits, the first two bits can be used to indicate the activated SRS resource set, and the remaining bits can be used to indicate the SRS activation offset value. Enhanced aperiodic SRS transmission(s) In various configurations, a WTRU can be instructed to operate in one or more aperiodic SRS transmission modes, for example, a legacy mode (e.g., the first mode in Figure 9) and / or an enhanced mode (e.g., the second mode in Figure 9). In some instances, a WTRU can be configured semi-statically or dynamically to operate in one of one or more aperiodic SRS transmission modes. For example, for dynamic operation, a WTRU can be explicitly instructed by L1 signaling (e.g., by DCI) to operate in an enhanced mode. Alternatively, a WTRU can implicitly determine its aperiodic SRS transmission mode. In one example, with reference to Figure 9, a mode determination mechanism / procedure for the aperiodic SRS transmission(s) is provided. In this example, a WTRU can determine or select an operating mode (or mechanism / procedure) for the aperiodic transmission(s) based on (or using) explicit or implicit information. In one mode, for SRS transmission (e.g., aperiodic SRS transmission), a WTRU can receive an SRS configuration from one or more SRS resource sets, and each SRS resource set is associated with a slot offset and / or a set of slot offset deltas. The WTRU can receive an SRS request / indication in a DCI, and the SRS request can indicate one SRS resource set from one or more SRS resource sets. The WTRU can determine a mode (or scheme) for SRS transmission, for example, based on any combination 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) an RNTI used to encode the DCI CRC. In one example, when the WTRU determines to use a first SRS mode (e.g., a legacy mode, or the first mode in Figure 9), the WTRU can determine (or select) one or more slots for the SRS transmission(s) based on (or using) a slot offset associated with a respective SRS resource set. In another example, when the WTRU determines to use a second SRS mode (e.g., an enhanced mode, or the second mode in Figure 9), the WTRU can determine (or select) at least one slot offset delta from the set of slot offset deltas associated with a respective SRS resource set. In some cases, the WTRU can determine (or select) at least one slot displacement delta based on a received indication (e.g., in the DCI described above, another DCI, or a CE MAC) or determined information (e.g., from an RNTI, such as the RNTI used to encode the DCI CRC).The WTRU can determine a slot for an SRS transmission based on (or using) the slot offset (associated with the SRS resource pool) plus the determined slot offset delta. The WTRU can, in the determined slot, transmit an SRS on one or more resources from the SRS resource pool. Various methods, devices, and / or systems for flexible aperiodic RS (e.g., SRS) transmissions in wireless communications are described. In one modality, a method (e.g., implemented in WTRU 102) for wireless communications includes receiving configuration information from one or more SRS resource sets, each SRS resource set from one or more SRS resource sets being associated with a slot offset and a set of slot offset deltas; receiving DCI indicating an SRS request, the SRS request indicating an SRS resource set from one or more SRS resource sets; determining an SRS configuration from a set of SRS configurations for SRS transmissions; determining a slot for transmitting an SRS based on the determined SRS configuration; and transmitting, in the determined slot, the SRS using resources from the indicated SRS resource set. In one mode, the SRS configuration is determined from the set of SRS configurations for SRS transmissions based on any 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 encode a cyclic redundancy check (CRC) for the DCI. In one example, the slot for transmitting SRS is determined based on the slot offset associated with the specified SRS resource set. In one modality, the method may also include determining a slot offset delta from the set of slot offset deltas associated with the specified SRS resource set, and the slot for transmitting SRS is determined based on 1) the slot offset associated with the specified SRS resource set, and 2) the determined slot offset delta. In one example, the slot offset delta is determined from the set of slot offset deltas based on any of: 1) the received configuration information, 2) the received DCI, 3) the determined SRS configuration, 4) a search space or CORESET in which the DCI is received, 5) a DCI format, 6) an indication in the DCI, 7) the RNTI used to encode a cyclic redundancy check (CRC) for the DCI, or 8) a CE MAC.In one mode, the slot for transmitting SRS is determined based on the slot offset associated with the SRS resource pool plus the specified slot offset delta. In another mode, configuration information for one or more SRS resource pools is received via a Radio Resource Control (RRC) signal. In one embodiment, a method (e.g., implemented in WTRU 102) for wireless communications includes receiving a first SRS configuration that includes first slot information, receiving a second SRS configuration that includes second slot information, and determining a slot index for an SRS transmission based on the first and second slot information. The method may also include transmitting an aperiodic SRS using the determined slot index. In one example, the first slot information comprises a slot offset value. In another example, the second slot information comprises one or more delta offset values, and these values ​​are used to correct the slot offset value. In yet another example, the method may include combining the slot offset value and the one or more delta offset values.In one example, the second SRS configuration is received via the DCI or a CE MAC. In one example, at least one of the first SRS configurations and the second SRS configuration is a Radio Resource Control (RRC) configuration. In one mode, a method (e.g., implemented in WTRU 102) for wireless communications includes receiving a set of parameters for a set of SRS resources, determining that an aperiodic SRS transmission is triggered based on the DCI, and transmitting an aperiodic SRS based on the parameter set. In one example, the aperiodic SRS transmission is triggered by a WTRU-specific DCI, a common group DCI, or an uplink DCI. In one mode, the method may include determining one or more slot offsets for the SRS resource set. In one example, the one or more slot offsets are determined based on one or more DCI formats. In one embodiment, a method (e.g., implemented in WTRU 102) for wireless communications includes receiving an indication that triggers an aperiodic RS transmission; determining, based on the indication, a slot and a new slot format for the aperiodic RS transmission, characterized in that the new slot format indicates that a different slot format is used for the slot; and transmitting the aperiodic RS in the slot using the new slot format. Indication(s) of slot formats for aperiodic SRS transmission(s) In NR, for TDD operation, a WTRU can be configured (e.g., by upper layers) to operate with 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, an RRC parameter tdd-UL-DL-ConfigurationCommon provides a general pattern of slots within a preconfigured periodicity. In various configurations, a WTRU can be additionally provided with a tdd-UL-DLConfigurationDedicated parameter to override flexible (F) symbols per slot over the number of slots specified by tdd-UL-DLConfigurationCommon. For a set of symbols in a slot that are specified as flexible by tdd-UL-DLConfigurationCommon or tdd-UL-DL-ConfigurationDedicated, a WTRU can receive a DCI 2_0 format with an SFI index field value that can indicate a new slot format [2]. In various configurations, a WTRU can be set to operate in aperiodic SFI mode. If aperiodic SFI mode is set, for example, when the WTRU receives an L1 or L2 command that triggers an aperiodic RS signal transmission, the received information element (IE) can also serve as a slot format indicator. In one example, the slot format indicator can be used to indicate / determine a format change. For instance, based on the information provided by the slot format indicator, the WTRU can change the format of the slot designated for aperiodic RS transmission to another slot format required for RS transmission. In one mode, if the slot indicated for an aperiodic RS transmission of UL (or DL) is already a UL (or DL) slot, the slot format indicated by the IE can only be a type F, and the indicated slot format (e.g., a type F) has a composition of UL, DL and / or F symbols. In one instance, if the slot specified for aperiodic RS transmission is a UL slot, the specified slot type may be DL or F, and the new specified DL or F slot format may cancel and replace the previous slot type with a new combination of UL, DL, and / or F symbols. In another example, if the slot specified for aperiodic RS transmission is a DL slot, the specified slot type may be UL or F, and the new specified UL or F slot format may cancel and replace the previous slot type with a new combination of UL, DL, and / or F symbols. In one mode, if the slot specified for aperiodic SRS transmission is an F slot, the specified slot type may be DL, UL, or an F type (e.g., a new F type), where the new specified DL, UL, or F slot format may override and replace the previous slot type with a new composition of UL, DL, and / or F symbols. For example, the WTRU may determine that the slot specified for aperiodic SRS transmission is an F slot having a first F slot type, and the WTRU may determine that the specified slot format is a DL slot type, a UL slot type, or a new F slot type (e.g., a second F slot type that is different from the first F slot type), where the newly specified DL, UL, or F slot format / type (e.g., a new composition of UL, DL, and / or F symbols) may be used for the slot specified for aperiodic SRS transmission. In various configurations, a WTRU can be set to operate in an SFI_aperiodic mode. For example, if SFI_aperiodic mode is configured, when the WTRU receives a DCI that activates an aperiodic SRS transmission, the received DCI can also serve as a slot format indicator. This slot format indicator can be used to signal a format change. For instance, based on the information provided by the slot format indicator, the WTRU can change the format of the slot designated for aperiodic SRS transmission to another slot format suitable for SRS transmission. Therefore, the WTRU may not need to receive a separate DCI format (e.g., DCI format 2_0) to adapt the slot designated for SRS transmission to a slot with a UL transmission opportunity. In one mode, if the slot specified for an aperiodic SRS transmission is already a UL slot, the slot format specified by the IE can only be a type F, and the specified slot format (e.g., a type F) has a composition of UL, DL and / or F symbols. In one instance, if the slot specified for aperiodic RS transmission is a UL slot, the specified slot type may be DL or F, and the new specified DL or F slot format may cancel and replace the previous slot type with a new combination of UL, DL, and / or F symbols. In another example, if the slot specified for aperiodic RS transmission is a DL slot, the specified slot type may be UL or F, and the new specified UL or F slot format may cancel and replace the previous slot type with a new combination of UL, DL, and / or F symbols. In one mode, if the slot specified for aperiodic SRS transmission is an F slot, the specified slot type may be DL, UL, or an F type (e.g., a new F type), where the new specified DL, UL, or F slot format may override and replace the previous slot type with a new composition of UL, DL, and / or F symbols. For example, the WTRU may determine that the slot specified for aperiodic SRS transmission is an F slot having a first F slot type, and the WTRU may determine that the specified slot format is a DL slot type, a UL slot type, or a new F slot type (e.g., a second F slot type that is different from the first F slot type), where the newly specified DL, UL, or F slot format / type (e.g., a new composition of UL, DL, and / or F symbols) may be used for the slot specified for aperiodic SRS transmission. In various modes, an IE that triggers an aperiodic RS transmission can carry a field (e.g., an SFI index) that indicates a specific slot format. In one mode, to reduce the overhead associated with the IE, instead of the SFI index, a WTRU can receive a new index (e.g., SFI_index_aperiodic) that can be smaller than an SFI_ index. In one example, the new index (e.g., SFI—index_aperiodic) can select only a subset of slot format options from an original SFI table (e.g., shown in Ref. [2]). In another mode, a WTRU can be configured (e.g., by upper layers) with one or more slot formats specific to an aperiodic RS transmission, and each configured slot format can correspond to a preferred slot format for the transmission, e.g., UL, DL, or F. As such, when a WTRU receives an IE that triggers an aperiodic RS transmission, the WTRU can use a specific slot format configured by upper layers. Figures 10A and 10B illustrate examples of configuring a slot format indication using an activating DCI for aperiodic SRS transmission(s). In some cases, even if a slot designated for SRS transmission is a flexible (F) slot with some symbols to allocate for a UL transmission, the designated slot may still not have a sufficient number of symbols to accommodate SRS transmissions. To accommodate SRS transmissions, the WTRU can receive, determine, or configure itself with a slot format indication using an activating DCI for the aperiodic SRS transmission(s). With reference to Figures 10A and 10B, in an example as shown in Figure 10A, the activating DCI can change the slot type (e.g., from a type F with fewer UL symbols) to a full UL slot (e.g., which has only UL symbols).In another example, as shown in Figure 10B, the activator DCI can change the slot format (e.g., from a flexible format that has fewer UL symbols) to another flexible format with more UL symbols. Although the features and elements were described above in particular combinations, a person skilled in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. Furthermore, the methods described herein can be implemented in a computer program, software, or firmware embedded on a computer-readable medium for execution by a computer or processor. Examples of non-transient computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard drives and removable disks, magneto-optical media, and optical media such as CD-ROMs and digital versatile discs (DVDs).A processor in association with software can be used to implement a radio frequency transceiver for use in a WTRU 102, UE, terminal, base station, RNC or any host computer. Furthermore, in the modalities described above, processing platforms, computer systems, controllers, and other devices containing processors are observed. These devices may contain at least a central processing unit (CPU) and memory. According to the practices of experts in computer programming techniques, reference to actions and symbolic representations of operations or instructions can be made through the various CPUs and memories. Such actions, operations, or instructions can be referred to as being executed, executed by the computer, or executed by the CPU. A person skilled in the art will appreciate that the symbolically represented actions, functions, or instructions involve the manipulation of electrical signals by the CPU. An electrical system represents data bits that can cause a transformation or reduction of electrical signals and the storage of data bits in memory locations within a memory system to reconfigure or otherwise modify the operation of the CPU, as well as other signal processing. The memory locations where the data bits are stored are physical locations with particular electrical, magnetic, optical, or organic properties that correspond to or are representative of the data bits. It should be understood that the representative modalities are not limited to the platforms or CPUs mentioned above and that other platforms and CPUs may support the methods described. Data bits can also be stored on a computer-readable medium that includes magnetic disks, hard drives, and other disks. 100 optical media, and any other volatile (e.g., random access memory (RAM)) or non-volatile (e.g., read-only memory (ROM)) mass storage system readable by the CPU. Computer-readable media may include cooperating or interconnected computer-readable media that exist exclusively within the processing system or are distributed among multiple interconnected processing systems, which may be local or remote to the processing system. It should be understood that representative modalities are not limited to the memories mentioned above and that other platforms and memories may support the methods described. In an illustrative manner, any of the operations, processes, etc., described herein can be implemented as computer-readable instructions stored on a computer-readable medium. These computer-readable instructions can be executed by a processor in a mobile unit, a network element, and / or any other computing device. There is little distinction between hardware and software implementations of aspects of systems. The use of hardware or software is generally (but not always, as in certain contexts the choice between hardware and software can become significant) a design choice that represents cost trade-offs compared to 101. Effectiveness. There may be various vehicles through which the processes and / or systems and / or other technologies described herein can be implemented (e.g., hardware, software, and / or firmware), and the preferred vehicle may vary depending on the context in which the processes and / or systems and / or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may choose a primarily hardware and / or firmware vehicle. If flexibility is paramount, the implementer may choose a primarily software implementation. Alternatively, the implementer may choose some combination of hardware, software, and / or firmware. The preceding detailed description has illustrated various embodiments of devices and / or processes using block diagrams, flowcharts, and / or examples. To the extent that such block diagrams, flowcharts, and / or examples contain one or more functions and / or operations, those within the art shall understand that each function and / or operation within such block diagrams, flowcharts, or examples may be implemented, individually and / or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. Suitable processors include, by way of example, a general-purpose processor, a special-purpose processor 102 special, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, application-specific integrated circuits (ASICs), application-specific specialty products (ASSPs); field-programmable gate array circuits (FPGAs), any other type of integrated circuit (IC) and / or a state machine. Although the features and elements were described above in particular combinations, a person skilled in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. The present description should not be limited to the particular embodiments described herein, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be evident to those skilled in the art. No element, action, or instruction used in the description herein should be construed as critical or essential to the invention unless explicitly stated as such.Functionally equivalent methods and apparatus within the scope of the description, in addition to those listed in the present description, will be evident to those skilled in the art from the descriptions. 103 above. It is anticipated that such modifications and variations will fall within the scope of the appended claims. The present description shall be limited only by the terms of the appended claims, together with the full scope of the equivalents to which such claims are entitled. It is understood that this description is not limited to any particular methods or systems. Furthermore, it should be understood that the terminology used in this description is intended to describe only particular modalities and is not intended to be limiting. As used in this description, when mentioned herein, the terms station and its abbreviation STA, user equipment and its abbreviation UE may mean (i) a wireless transmitting and / or receiving unit (WTRU), as described below; (ii) any of a number of modalities of a WTRU, as described below; (iii) a wireless and / or wired capable (e.g., installable) device configured with, among other things, some or all of the structures and functionalities of a WTRU, as described below; (iv) a wireless and / or wired capable device configured with less than all of the structures and functionalities of a WTRU, as described below; or (v) the like.Details of an illustrative WTRU, which may be representative of any EU. 104 mentioned in the present description, are provided later with respect to Figures 1A-1D. In certain representative embodiments, various portions of the subject matter described herein may be implemented through application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments described herein, in whole or in part, may be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), or as one or more programs running on one or more processors (e.g.,(as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and who design the circuit system and / or write the code for the software and / or firmware would fall well within the expertise of a person skilled in the art in light of this description. Furthermore, those skilled in the art will appreciate that the mechanisms of the subject matter described herein can be distributed as a program product in a variety of forms, and that an illustrative modality of 105 The subject matter described herein applies regardless of the particular type of signal-carrying medium used to actually carry out the distribution. Examples of a signal-carrying medium include, but are not limited to, the following: a recordable medium, such as a floppy disk, a hard disk drive, a CD, a DVD, a digital tape, a computer memory, etc., and a transmission medium, such as a digital and / or analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communication link, a wireless communication link, etc.). The subject matter described herein sometimes illustrates different components contained within, or connected to, other different components. It should be understood that such depicted architectures are merely examples, and that many other architectures can in fact be implemented to achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively associated in such a way that the desired functionality can be achieved. Therefore, any two components in this description combined to achieve a particular functionality can be viewed as associated with each other in such a way that the desired functionality is achieved, regardless of intermediate architectures or components. Similarly, any two 106 components associated in this way can also be seen as functionally connecting or coupling with each other to achieve the desired functionality, and any two components capable of being associated in this way can also be seen as being able to functionally couple with each other to achieve the desired functionality. Specific examples of components that can be functionally coupled include, but are not limited to, components that can be physically coupled and / or that physically interact and / or components that can interact wirelessly and / or that interact wirelessly and / or components that interact logically and / or that can interact logically. With regard to the use of any plural and / or singular term in this description, those skilled in the art may translate from plural to singular and / or from singular to plural as appropriate to the context and / or application. Various singular / plural permutations may be expressly stated in this description for clarity. Those skilled in the art will understand that, generally, the terms used in the present description and, especially, in the appended claims (e.g., the bodies of the appended claims) are generally intended as open terms (e.g., the term that 107. The term "includes" should be interpreted as including, but not limited to; the term "has" should be interpreted as having at least; the term "includes" should be interpreted as including, but not limited to, etc.) Those within the art will further understand that if a specific number of a reference is provided for in accordance with the introduced claim, this intention shall be explicitly stated in the claim, and in the absence of such a statement, no such intention is present. For example, where only one article is provided for, the term "single" or similar language may be used. As an aid to understanding, the following appended claims and / or the descriptions in the present description may contain the use of the introductory phrases "at least one" and "one or more" to introduce the references in accordance with the claim.However, the use of such phrases should not be interpreted as implying that the introduction of a reference in accordance with the claim by the indefinite articles a or an limits any particular claim containing such a reference in accordance with the introduced claim to the modalities containing only one of such a reference, even when the same claim includes the introductory phrases one or more or at least one and indefinite articles such as a or an (e.g., a and / or an should be interpreted to mean at least one or one or more). 108 The same applies to the use of definite articles used to introduce the references according to the claim. Furthermore, even if a specific number of a reference according to the introduced claim is explicitly mentioned, those skilled in the art will recognize that such a reference must be interpreted as meaning at least the number mentioned (e.g., the simple mention of two references, without any other modifiers, means at least two references, or two or more references). Furthermore, in those cases where a convention analogous to at least one of A, B, and C, etc., is used, this structure is generally intended to be understood by a person experienced in the technique (e.g., a system having at least one of A, B, and C would include, but not be limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). Those within the technical field will understand, 109 Furthermore, virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or figures, should be understood to include the possibilities of one of the terms, any of the terms, or both terms. For example, the phrase A or B should be understood to include the possibilities of A or B or A and B. In addition, the term "any of" followed by a list of a plurality of articles and / or a plurality of categories of articles, as used herein, is intended to include any of, any combination of, any multiple of, and / or any combination of multiples of the articles and / or categories of articles, individually or together with other articles and / or categories of articles. Furthermore, as used herein, the term "assembly" or "group" is intended to include any number of articles, including zero.Furthermore, as used in this description, the term number is intended to include any number, including zero. Furthermore, when the characteristics or aspects of the description are described in terms of Markush groups, experts in the technique will recognize that the description is also described in this way in terms of any individual member or subgroup of members of the Markush group. As any expert in the field will understand, for anyone 110 and the entirety of the purposes, such as in terms of providing a written description, all intervals described herein also encompass any and all possible subintervals and combinations thereof. Any interval stated may be readily recognized as sufficiently describing and permitting that same interval to be divided into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each interval described herein may be readily divided into a lower third, a middle third, and an upper third, etc. Furthermore, as one skilled in the art will understand, all phrases such as up to, at least, greater than, less than, and the like include the aforementioned number and refer to intervals that may be further divided into subintervals as described above.Finally, as someone proficient in the technique will understand, an interval includes each individual member. Therefore, for example, a group that has 1-3 cells refers to groups that have 1, 2, or 3 cells. Similarly, a group that has 1-5 cells refers to groups that have 1, 2, 3, 4, or 5 cells, and so on. Furthermore, the claims should not be construed as being limited to the order or the items provided unless expressly stated otherwise. Additionally, the use of the term "means to" in any claim is intended to invoke 35 U.S.C. 111 §112, 1 6 or the format of a means plus function claim and no claim is provided for without the term means for. A software-associated processor can be used to implement a radio frequency transceiver for use in a wireless transmit / receive unit (WTRU), user equipment (UE), terminal, base station, mobility management entity (MME), evolved packet kernel (EPC), or any host equipment.The WTRU can be used in conjunction with modules, implemented in hardware and / or software including software-defined radio (SDR), and other components, such as a camera, video camera module, videophone, loudspeaker, vibration device, speaker, microphone, transceiver television, hands-free headset, keyboard, Bluetooth® module, frequency modulated (FM) radio unit, near field communication (NEC) module, liquid crystal display (LCD) unit, organic light-emitting diode (OLED) display unit, digital music player, media player, video game player module, internet browser, and / or any wireless local area network (WLAN) or ultra-wideband (UWB) module. 112 Although the invention has been described in terms of communication systems, it is envisaged that the systems can be implemented in software on general-purpose microprocessors / computers (not shown). In certain embodiments, one or more of the functions of the various components can be implemented in software that controls a general-purpose computer. Furthermore, although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications to the details may be made within the scope and range of equivalents of the claims and without departing from the invention. Throughout the description, an expert in the technique will understand that certain representative modalities can be used in the alternative or in combination with other representative modalities. Although the features and elements were described above in particular combinations, a person skilled in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. Furthermore, the methods described herein can be implemented in a computer program, software, or firmware embedded in a computer-readable medium for execution by a 113. Computer or processor. Examples of non-transient, computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard drives and removable disks, magneto-optical media, and optical media such as CD-ROMs and digital versatile discs (DVDs). A processor in conjunction with software can be used to implement a radio frequency transceiver for use in a WRTU, UE, terminal, base station, RNC, or any host computer. Furthermore, in the modalities described above, processing platforms, computer systems, controllers, and other devices containing processors are observed. These devices may contain at least a central processing unit (CPU) and memory. According to the practices of experts in computer programming techniques, reference to actions and symbolic representations of operations or instructions can be made through the various CPUs and memories. Such actions, operations, or instructions can be referred to as being executed, executed by the computer, or executed by the CPU. An expert in the technique will appreciate that the actions and the 114 Operation or symbolically represented instructions include the manipulation of electrical signals by the CPU. An electrical system represents data bits that can cause a transformation or reduction resulting from electrical signals and the holding of data bits in memory locations in a memory system to, in this way, reconfigure or otherwise modify the operation of the CPU, as well as other signal processing. The memory locations where data bits are held are physical locations that have particular electrical, magnetic, optical, or organic properties that correspond to or are representative of the data bits. Data bits can also be stored 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 system readable by the CPU. Computer-readable media may include cooperating or interconnected computer-readable media that exist exclusively within the processing system or are distributed among multiple interconnected processing systems, which may be local or remote to the processing system. It should be understood that the representative modalities are not limited to the memories mentioned. 115 above and that other platforms and memories can support the methods described. Suitable processors include, by way of example, a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, application-specific integrated circuits (ASICs), application-specific specialty products (ASSPs); field-programmable gate array (FPGA) circuits, any other type of integrated circuit (IC) and / or a state machine. Although the invention has been described in terms of communication systems, it is envisaged that the systems can be implemented in software on general-purpose microprocessors / computers (not shown). In certain embodiments, one or more of the functions of the various components can be implemented in software that controls a general-purpose computer. Furthermore, although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications to the details may be made. 116 within the scope and range of equivalents of the claims and without departing from the invention. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

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

2. The method according to claim 1, characterized in that it further comprises determining an RS configuration from a set of RS configurations for RS transmissions.

3. The method according to claim 2, 118 characterized in that the RS configuration is determined from the set of RS configurations for RS transmissions based on any 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 encode a cyclic redundancy check (CRC) for the DCI.

4. The method according to claim 1, characterized in that the one or more sets of RS resources comprise one or more sets of sound reference signal (SRS) resources.

5. The method according to claim 1, characterized in that the slot for transmitting the RS is further determined based on the slot offset associated with at least one set of RS resources.

6. The method according to claim 1, characterized in that it further comprises: determining a slot displacement delta from the set of slot displacement deltas associated with the at least one set of RS resources, and wherein the slot for transmitting the RS is further determined based on 1) the slot displacement associated with the at least one set of RS resources and 2) the determined slot displacement delta.

7. The method according to claim 6, 119 characterized in that the slot displacement delta of the set of slot displacement deltas is determined based on any of: 1) the received configuration information, 2) the received DCI, 3) an RS configuration from a set of RS configurations for RS transmissions, 4) a search space or CORESET in which the DCI is received, 5) a DCI format, 6) an indication in the DCI, 7) a radio network temporary identifier (RNTI) used to encode a cyclic redundancy check (CRC) for the DCI, or 8) a medium access control (MAC) control element (CE).

8. The method according to claim 6, characterized in that the slot for transmitting the RS is further determined based on the slot displacement associated with the at least one set of RS resources plus the determined slot displacement delta.

9. The method according to claim 1, characterized in that the configuration information of one or more RS resource sets is received via a radio resource control (RRC) signaling.

10. The method according to claim 1, characterized in that each RS resource set of one or more RS resource sets is associated with a respective slot offset and a respective slot offset delta set. 120 11. A wireless transmit / receive unit (WTRU) for wireless communications, characterized in that it comprises: a receiver configured to: receive configuration information from one or more sets of reference signal (RS) resource sets, wherein at least one RS resource set from the one or more RS resource sets is associated with a slot offset and a set of slot offset deltas, and receive downlink control information (DCI) indicating an RS request, wherein the RS request indicates at least one RS resource set from the one or more RS resource sets; a processor configured to determine a slot for transmitting an RS based on at least one RS resource set; and a transmitter configured to transmit the RS in the determined slot.

12. The WTRU according to claim 11, characterized in that the processor is further configured to determine an RS configuration from a set of RS configurations for RS transmissions.

13. The WTRU according to claim 12, characterized in that the RS configuration is determined from the set of RS configurations for the 121 RS transmissions based on any of: 1) a search space or CORESET in which the DCI is received, 2) a DCI format, 3) an indication in the DCI, and 4) a radio network time identifier (RNTI) used to encode a cyclic redundancy check (CRC) for the DCI.

14. The WTRU according to claim 11, characterized in that the one or more sets of RS resources comprise one or more sets of sound reference signal (SRS) resources.

15. The WTRU according to claim 11, characterized in that the slot for transmitting RS is further determined based on the slot offset associated with at least one set of RS resources.

16. The WTRU according to claim 11, characterized in that the processor is further configured to determine a slot displacement delta from the set of slot displacement deltas associated with at least one set of RS resources, and wherein the slot for transmitting the RS is further determined based on 1) the slot displacement associated with the at least one set of RS resources and 2) the determined slot displacement delta.

17. The WTRU according to claim 16, characterized in that the slot displacement delta of the slot displacement delta set is determined based on any of: 1) the received configuration information, 2) the received DCI, 3) an RS configuration from a set of RS configurations for RS transmissions, 4) a search space or CORESET in which the DCI is received, 5) a DCI format, 6) an indication in the DCI, 7) a radio network temporary identifier (RNTI) used to encode a cyclic redundancy check (CRC) for the DCI, or 8) a medium access control (MAC) control element (CE).

18. The WTRU according to claim 16, characterized in that the slot for transmitting RS is further determined based on the slot offset associated with the at least one set of RS resources plus the determined slot offset delta.

19. The WTRU according to claim 11, characterized in that the configuration information of one or more RS resource sets is received through a radio resource control (RRC) signaling.

20. The WTRU according to claim 11, characterized in that each RS resource set of one or more RS resource sets is associated with a respective slot offset and a respective slot offset delta set.

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