Method and apparatus for multi-TRP SRS enhancement in TDD

Abstract

A method and a wireless transmit / receive unit (WTRU) for multiple transmit and receive point (mTRP) transmissions may include a WTRU configured to receive configuration information indicating a sounding reference signal (SRS) resource set including at least one or more SRS resources, one or more SRS parameters, and one or more time-based patterns. The WTRU may be configured to receive an indication to activate a time-based mode of the one or more time-based modes. The WTRU may be configured to transmit a first SRS in a first time instance using a first SRS resource of the one or more SRS resources and a first SRS parameter of the one or more SRS parameters. The WTRU may be configured to transmit a second SRS in a second time instance different from the first time instance using the first SRS resource and a second SRS parameter.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 334,994, filed on April 26, 2022, and U.S. Provisional Application No. 63 / 422,666, filed on November 4, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] 5G New Radio (NR) supports reciprocity-based channel estimation and precoding in time division duplex (TDD) scenarios where the sounding reference signal (SRS) resource usage is set to antennaSwitching. When the wireless transmit / receive unit (WTRU) transmits the SRS, the uplink (UL) channel can be estimated at the gNB and the same channel can be assumed for the downlink (DL) because the UL and DL can be transmitted on the same carrier frequency. The gNB can use the UL channel to determine the downlink precoder. Summary of the invention

[0004] A method and wireless transmit / receive unit (WTRU) for multi-transmit and receive point (mTRP) transmission may include a WTRU configured to receive configuration information indicating a set of sounding reference signal (SRS) resources, the set of sounding reference signal (SRS) resources including at least one or more SRS resources, one or more SRS parameters, and one or more time-based patterns. The WTRU may be configured to receive an indication of activating a time-based pattern of the one or more time-based patterns. The WTRU may be configured to transmit a first SRS in a first time instance using a first SRS resource of the one or more SRS resources and a first SRS parameter of the one or more SRS parameters. The first SRS resource and the first SRS parameter may be determined based on the activated time-based pattern. The WTRU may be configured to transmit a second SRS in a second time instance different from the first time instance using the first SRS resource and the second SRS parameter. The second SRS parameter may be determined based on the activated time-based pattern. The configuration information may further indicate a plurality of path loss reference signals (PL RSs). The configuration information may further indicate an association between each SRS resource and a corresponding subset of the plurality of PL RSs. The first SRS may be transmitted using a transmit power determined based on a PL RS in the plurality of PL RSs. The PL RS may be determined based on an activated time-based mode. The second SRS may be transmitted using a transmit power determined based on a PLRS in the plurality of PL RSs. The PL RS may be determined based on an activated time-based mode. The first SRS parameter and the second SRS parameter may be a respective first cyclic shift (CS) and a second cyclic shift (CS), and the first CS and the second CS may be different. The indication of activating the time-based mode may be received in a downlink control information (DCI) or a medium access control (MAC) control element (CE). The WTRU may be further configured to determine a time-based mode to be activated based on the indication of activating the time-based mode. The one or more SRS parameters may include a cyclic shift, a comb, a time offset, a sequence index, or a group index. The first SRS parameter may be based on the activated time-based mode and the first time instance, and the second SRS parameter may be based on the activated time-based mode and the second time instance. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more detailed understanding may be obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements, and in which:

[0006] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0007] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system;

[0008] Figure 1C is an example of an embodiment in which Figure 1A a system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0009] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0010] Figure 2 is an example of SRS transmission in mTRP;

[0011] Figure 3 is an example of a method for dynamically combining SRS configuration and offset triggering;

[0012] Figure 4 An example SRS offset code point indicator association is shown;

[0013] Figure 5 An example association of offset to SRS configuration is shown;

[0014] Figure 6 An example method of mTRP SRS transmission is shown;

[0015] Figure 7 An example method of mTRP SRS transmission is shown;

[0016] Figure 8 An example method of mTRP SRS transmission is shown;

[0017] Fig. 9 An example time-based schema is shown; and

[0018] Fig.10 Example mTRP SRS transmission based on the activated mode is shown. DETAILED DESCRIPTION

[0019] Figure 1A1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0020] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a station (STA)) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0021] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B such as a gNode B (gNB), a new radio (NR) Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0022] The base station 114a may be part of the RAN 104, 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), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0023] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0024] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), that may use Wideband CDMA (WCDMA) to establish the air interface 116. WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​Uplink (UL) Packet Access (HSUPA).

[0025] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0026] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology (such as NR radio access) that may establish the air interface 116 using NR.

[0027] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0028] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0029] Figure 1A The base station 114b in the example may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a micro-micro cell base station or a femto cell base station. As Figure 1A As shown, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b may not be required to access the Internet 110 via the CN 106.

[0030] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the specification, the CN 106 may be configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0031] The CN 106 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0032] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0033] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0034] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0035] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In one embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0036] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0037] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0038] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0039] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0040] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0041] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors. The sensor may be one or more of the following: a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geographic location sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor, etc.

[0042] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and DL (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., a choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or DL ​​(e.g., for reception)) may be concurrent and / or simultaneous.

[0043] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with one embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0044] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0045] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0046] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0047] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0048] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0049] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0050] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0051] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0052] In a representative embodiment, the other network 112 may be a WLAN.

[0053] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0054] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20MHz wide bandwidth) or a dynamically set width. The primary channel may be a working channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0055] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0056] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0057] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter type control / machine type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0058] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operation mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. In the case where the primary channel is busy, for example, because a STA (which only supports a 1MHz operation mode) is transmitting to the AP, all available bands may be considered busy even if most of the available bands remain idle.

[0059] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0060] Figure 1D1 is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As noted above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0061] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and gNB 180b (and / or gNB 180c).

[0062] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths over time).

[0063] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0064] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, interworking between DC, NR, and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0065] Figure 1D The illustrated CN 106 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although the aforementioned elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0066] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. The AMF 182a, 182b may use network slicing in order to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0067] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 106 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 106 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0068] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, etc.

[0069] The CN 106 may facilitate communications with other networks. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to the DNs 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the local DNs 185a, 185b.

[0070] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following items may be performed by one or more simulation devices (not shown): WTRU102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMF 182a-182b, UPF 184a-184b, SMF 183a-183b, DN 185a-185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0071] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0072] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0073] As discussed in 3GPP RP-213598, 3GPP Release 18 Multiple Input Multiple Output (MIMO) aims to improve channel state information (CSI) acquisition for TDD coherent joint transmission (C-JT) through enhancements to the sounding reference signal (SRS). Assuming ideal backhaul and synchronization and the same number of antenna ports between TRPs, enhancements to CSI acquisition for coherent-JT (targeting FR1 and up to 4 transmit / receive points (TRPs)) are studied (and if justified) specified as follows: SRS enhancements to manage cross-SRS interference between TRPs targeting TDD C-JT via SRS capacity enhancement and / or interference randomization, with the constraints that: 1) no additional resources for SRS are consumed; 2) the existing SRS comb structure is reused; and 3) there are no new SRS root sequences. Figure 2 An example of SRS transmission in multiple TRPs (mTRPs) is shown.

[0074] For SRS configuration in 3GPP Release 17: only one spatial filter is associated with each SRS resource; only one power control parameter set is active at a time for an SRS resource; and for aperiodic SRS (A-SRS), the downlink control information (DCI) may indicate a 2-bit codepoint: do not trigger an SRS resource set, or trigger a resource set with codepoints 1, 2, or 3. The codepoint is configured as part of an SRS resource set with aperiodicSRS-resourceTrigger value and aperiodicSRS-resourceTriggerList value.

[0075] 3GPP Release 17 SRS resource configuration can flexibly allocate resources orthogonally or with low cross-correlation by moving the time / frequency position of the transmission and using different sequences / orthogonal cover codes (OCC). However, the resource set is configured for each TRP without considering the configuration of other TRPs. In mTRP, the WTRU may send SRS to more than one TRP to estimate multiple channels which may cause more congestion. This may result in higher interference between SRS resources sent from different WTRUs.

[0076] The following issues need to be considered: how does the WTRU determine the multi-TRP SRS resource configuration to reduce inter-TRP interference; and how does the WTRU determine which SRS resource combination to send for C-JT multi-TRP pre-decoder measurement.

[0077] Hereinafter, "a", "an" and similar phrases may be interpreted as "one or more" and "at least one". Similarly, any term ending with the suffix "(s)" may be interpreted as "one or more" and "at least one". For example, the term "may" may be interpreted as "may, for example".

[0078] The WTRU may send or receive information via a physical channel or send or receive a reference signal (RS) according to at least one spatial domain filter.The term "beam" may be used to refer to a spatial domain filter.

[0079] The WTRU may send information via a physical channel or send or receive a signal using the same spatial domain filter as used to receive an RS (e.g., CSI-RS) or synchronization signal (SS) block. The WTRU sending may be referred to as the "target" and the received RS or SS block may be referred to as the "reference" or "source". In this case, the WTRU may be said to send information via the target physical channel or send a signal based on a spatial relationship with reference to such RS or SS block.

[0080] The WTRU may send information via a first physical channel or send a signal according to the same spatial domain filter as used to send a signal or send information via a second physical channel. The first transmission and the second transmission may be referred to as "target" and "reference" (or "source"), respectively. In this case, the WTRU may be said to send information via a first (target) physical channel or send a signal according to a spatial relationship with reference to a second (reference) physical channel to send the signal.

[0081] The spatial relationship may be implicit, such as configured through RRC signaling, or signaled, such as through a medium access control (MAC) control element (CE) or DCI. For example, the WTRU may implicitly transmit through the PUSCH and the demodulation reference signal (DM-RS) for the PUSCH according to the same spatial domain filter as the SRS, which is indicated by the SRS resource indicator (SRI) indicated in the DCI or configured through RRC signaling. In one example, the spatial relationship may be configured through RRC for SRI or signaled through MAC CE for PUCCH. Such a spatial relationship may also be referred to as "beam indication".

[0082] The WTRU may receive a first (target) downlink channel transmission or signal based on the same spatial domain filter or spatial reception parameters as a second (reference) downlink channel transmission or signal. For example, such an association may exist between a physical channel such as a PDCCH or PDSCH and its corresponding DM-RS. Such an association may exist at least when the first signal and the second signal are reference signals and when the WTRU is configured with a quasi-colocation (QCL) assumption type D between the corresponding antenna ports. Such an association may be configured as a transmission configuration indicator (TCI) state. The WTRU may receive an indication of the association between a CSI-RS or SS block and a DM-RS by indexing a TCI state set configured by RRC signaling and / or signaled by a MAC CE. Such an indication may also be referred to as a "beam indication."

[0083] Hereinafter, RS may be used interchangeably with one or more of RS resource, RS resource set, RS port, and RS port group and still be consistent with the present disclosure.

[0084] Hereinafter, RS may be used interchangeably with one or more of SSB, CSI-RS, SRS, and DM-RS and still be consistent with the present disclosure.

[0085] Hereinafter, TRP (e.g., transmit and receive point) may be used interchangeably with one or more of TP (transmit point), RP (receive point), RRH (radio remote head), DA (distributed antenna), BS (base station), sector (of BS), and cell (e.g., geographic cell area served by BS), and still be consistent with the present disclosure. Hereinafter, multi-TRP may be used interchangeably with one or more of mTRP, m-TRP, and multiple TRPs, and still be consistent with the present disclosure.

[0086] The WTRU may be configured with or may receive configuration of one or more TRPs to which the WTRU may send and / or from which the WTRU may receive. The WTRU may be configured with one or more TRPs for one or more cells. A cell may be a serving cell or a secondary cell.

[0087] The WTRU may be configured with at least one RS for channel measurement. The RS may be represented as a channel measurement resource (CMR) and may include a CSI-RS, SSB, or other downlink RS sent from a TRP to the WTRU. The CMR may be configured with or associated with a TCI state. The WTRU may be configured with a CMR group that may include CMR indexes sent from the same TRP. Each group may be identified by a CMR group index (e.g., group 1). The WTRU may be configured to have one CMR group per TRP, and the WTRU may receive a link between a CMR group index and another CMR group index, or a link between an RS index from one CMR group and another RS ​​index from another group. The WTRU may determine that the linked resources may be configured for C-JT.

[0088] The WTRU may be configured with or receive configuration of one or more path loss (PL) reference groups (eg, sets) and / or one or more SRS groups, SRS resource indicators (SRIs), or SRS resource sets.

[0089] A PL reference group may correspond to or may be associated with a TRP. A PL reference group may include, identify, correspond to or be associated with one or more TCI states, SRIs, reference signal sets (e.g., CSI-RS sets, SRI sets), CORESET indices, and / or reference signals (e.g., CSI-RS, SSBs).

[0090] The WTRU may receive a configuration (e.g., any configuration described herein). The configuration may be received from the gNB or the TRP. For example, the WTRU may receive a configuration of one or more TRPs, one or more PL reference groups, and / or one or more SRI sets. The WTRU may implicitly determine the association between the RS set / group and the TRP. For example, if the WTRU is configured with two SRS resource sets, the WTRU may determine to transmit to TRP1 using the SRS in the first resource set and to transmit to TRP2 using the SRS in the second resource set. The configuration may be via RRC signaling, MAC CE, or DCI.

[0091] The WTRU may receive an indication of a primary TRP and a secondary TRP. When the WTRU is configured with multiple TRPs, it may determine that one of the TRPs is the primary TRP or the anchor TRP. This designation may be based on network configuration or WTRU determination (e.g., the received signal quality of one TRP is higher than the received signal quality of all other TRPs, or is higher than a threshold).

[0092] In the examples and embodiments described herein, TRP, PL reference set, SRI set, and SRI collection are used interchangeably. The terms "collection" and "group" are used interchangeably herein.

[0093] In the following, for simplicity of discussion, a coherent joint transmission system with two TRPs is considered, however the proposed solution and process can be equally applied to the case with more than two TRPs. In an exemplary embodiment, one of the TRPs can be considered as the primary TRP.

[0094] The attributes of the grant or assignment may include at least one of the following: frequency allocation; aspects of the time allocation, such as duration; priority; modulation and coding scheme; transport block size; number of spatial layers; number of transport blocks; TCI status, CRI, or SRI, where if multiple panels are used for UL transmission, the TCI status, CRI, or SRI may be used for each WTRU's panel; number of repetitions; type of repetition scheme (e.g., Type A or Type B); whether the grant is a configured grant type 1, type 2, or dynamic grant; whether the assignment is a dynamic assignment or semi-persistent scheduling (configured the configured grant index or semi-persistent assignment index; the configured periodicity of the grant or assignment; the channel access priority class (CAPC); any parameters provided in the DCI through the MAC or through the RRC for scheduling the grant or assignment; whether the grant is for a single TRP transmission or multiple TRP transmissions; whether the grant is for UL transmissions from a single WTRU panel (TxSP) or simultaneous UL transmissions from multiple WTRU panels (STxMP); or whether the grant is for C-JT or non-coherent joint transmission (NC-JT) transmissions.

[0095] The WTRU may report a subset of channel state information (CSI) components. The CSI components may correspond to at least a CSI-RS resource indicator (CRI), an SSB resource indicator (SSBRI), an indication of a panel for reception at the WTRU (such as a panel identity or a group identity), measurements such as L1 reference signal received power (RSRP) derived from SSB or CSI-RS, L1-SINR (e.g., cri-RSRP, cri-SINR, ssb-Index-RSRP, ssb-Index-SINR), and other channel state information (such as at least a rank indicator (RI), a channel quality indicator (CQI), a precoding matrix indicator (PMI), a layer index (LI), etc.).

[0096] The WTRU may receive an SRS configuration that may indicate an SRS resource set including one or more SRS resources. The SRS resources may be configured with a time domain location and a frequency domain location that may span one or more symbols and one or more RBs.

[0097] Frequency hopping may be used so that SRS resources may be sent in a preconfigured RB pattern over time, and repetition may be used to repeat the SRS over multiple symbols.

[0098] A comb structure may be used to change the granularity in the frequency domain to orthogonally multiplex multiple SRS resources in the frequency domain. For example, a comb of 2 may mean that SRS is transmitted every 2nd RE (e.g., only odd numbers or only even numbers), and the starting offset may be configured with respect to the PRB boundary so that the WTRU may determine which set of REs to use. For example, with a comb of 4, the WTRU may transmit on every 4th RE, and 4 possible offsets (e.g., 0, 1, 2, 3) may be configured as the starting point of the comb.

[0099] RB fraction frequency sounding (RPFS) may be configured so that the WTRU may send SRS in a portion of the bandwidth. The portion may be given by the RPFS (e.g., 1 / 2, 1 / 4). For example, an RPFS of 1 / 2 may mean that the WTRU may send SRS in even RBs or odd RBs. The RB offset may be configured to determine the starting point of the RPFS.

[0100] The WTRU may generate an SRS using a base sequence that may be mapped to OFDM symbols of an SRS resource based on a configured time / frequency mapping. The WTRU may receive a cyclic shift (CS) that determines the phase rotation applied to the base sequence. Different cyclic shifts of the same base sequence may generate SRS that are orthogonal to each other. For example, for a WTRU with more than one antenna port, one base sequence may be used and each port may use a different cyclic shift.

[0101] The base sequences may be grouped into 30 groups according to the sequence length, each group having a group index, and each group may be configured with up to two sequences, with a sequence index of 0 or 1. The WTRU may be configured with group hopping or sequence hopping, where the group index or sequence index is pseudo-randomly selected for each OFDM symbol and slot of the SRS resource.

[0102] A C-JT deployment may include multiple transmission points and their corresponding channels. In this case, the acquired CSI should reflect accurate information about the state of each link with minimal skew between the measurements of the participating links. Reference signal transmission associated with CSI measurements should occur with minimal interference. More than one WTRU may be served by a set of TRPs. Each WTRU may receive an SRS configuration that may be sent periodically or activated semi-statically. The network may receive SRS for UL channel estimation from more than one WTRU at the same time. This may result in high interference between SRSs sent to different TRPs. For example, a first WTRU (e.g., WTRU1) may send a first SRS (e.g., SRS1) to a first TRP (e.g., TRP1), and a second WTRU (e.g., WTRU2) may send a second SRS (e.g., SRS2) to a second TRP (e.g., TRP2). If two SRSs are sent simultaneously, the SRS1 transmission may interfere with the SRS2 transmission at the receiver of TRP2. Furthermore, the signaling associated with the configuration and triggering of SRS transmissions should not exceed significantly that of a single TRP transmission.

[0103] The WTRU may determine the SRS transmission parameters based on the TRP set and the activated TRP.

[0104] In one embodiment, the WTRU may receive configuration parameters M and N indicating the total number of potential transmission points and the number of transmission points activated for scheduled joint transmission, respectively.

[0105] In one embodiment, the WTRU may receive an information set that may include TRP common information and TRP specific information. The TRP common information may include some basic transmit parameters that may be shared between all TRPs (e.g., gNB antenna configuration, number of transmit ports, etc.). The WTRU may receive the TRP common information through semi-static or dynamic configuration (e.g., RRC signaling or MAC CE).

[0106] In one embodiment, the WTRU may receive a TRP-specific configuration for N1≥N TRPs via RRC signaling or a dynamic indication (e.g., MAC CE). The WTRU may receive another dynamic indication (e.g., DCI) to initiate a send or receive process associated with N TRPs out of the N1 TRPs.

[0107] The WTRU may receive multiple SRS resource set configurations. Each configuration may be TRP specific.

[0108] In one embodiment, the WTRU may receive a set of SRS configurations corresponding to SRS transmissions to multiple TRPs. In one embodiment, the WTRU may receive a configuration of SRS resource groups, where each resource group is configured for each TRP. For example, SRS resource group 1 may be configured with one or more SRS resource sets, and SRS resource group 2 may be configured with one or more SRS resource sets. Each resource group may be associated with a TRP. The WTRU may receive a pair of SRS resource sets for C-JT between SRS resource sets via RRC configuration or MAC-CE.

[0109] In one embodiment, the WTRU may use some of the configuration parameters commonly for all TRPs, such as configuration parameters configured as TRP common information. For example, the WTRU may receive a fixed comb value and / or number of SRS ports for SRS transmission associated with all TRPs. The configuration of TRP common SRS parameters may be performed via RRC configuration and / or MACCE.

[0110] In one embodiment, the WTRU may receive an SRS configuration corresponding to each of the N1 TRPs, e.g., TRP-specific. In one embodiment, the WTRU may receive a set of N1 TRP-specific configurations via RRC configuration or MAC CE indication. Such information may include, for example, reference signal indication for spatial beams, reference signal indication for path loss calculation or cyclic shift, frequency hopping information.

[0111] In one embodiment, the WTRU may receive an implicit or explicit indication to initiate SRS transmission. The received indication may also indicate N TRPs selected from a set of N1 TRPs for SRS transmission.

[0112] In one embodiment, the WTRU may receive a configuration to define valid time resources (e.g., time slots, symbols, etc.) for transmission of each SRS resource. The WTRU may receive at least one set of time resource definitions for each TRP link. In one embodiment, if the WTRU is configured with more than one set of time resources for a TRP, the WTRU may receive an indication (e.g., in a DCI field) for selecting a time resource in a received command triggering SRS transmission.

[0113] In one embodiment, the WTRU may receive a configuration that may include more than one TRP-specific configuration set per TRP. The WTRU may receive an indication of a usage pattern of the configured TRP-specific configurations (e.g., a table associating TRP-specific configurations with different time resources). The WTRU may receive an indication to randomly select one of the configuration sets for SRS transmission to the TRP. In one embodiment, the WTRU may select SRS transmission parameters to each TRP using a pseudo-random procedure (which may also be known to the gNB). The pseudo-random selection procedure may be defined based on one or more parameters (e.g., a cell index, a cell radio network temporary identifier (C-RNTI), etc.).

[0114] The WTRU may receive an SRS resource set configuration, which may include more than one TRP-specific SRS resources.

[0115] In one embodiment, the WTRU may receive a configuration for transmitting a set of SRS resources to multiple TRPs. One or more of the following may be used for the configuration and transmission of SRS to multiple TRPs.

[0116] A WTRU may be configured with more than one SRS resource. Each SRS resource may be associated with an SRS transmission to at least one TRP. In one embodiment, some parameters of an SRS resource may be common among all configured SRS resources, while some other parameters may vary depending on the associated TRP link. For example, all configured SRS resources may have the same bandwidth, but they may be configured with different cyclic shifts or other parameters.

[0117] The WTRU may transmit an SRS to each TRP using at least one spatial filter configuration. In one embodiment, the WTRU may use the same beam to transmit to all TRPs. In one embodiment, a WTRU with two transmit links may be configured to have K SRS transmit events for each link (e.g., a TRP link). The K transmit events to the TRP links may be configured to be sequential or interleaved.

[0118] In one embodiment, the link corresponding to the first SRS transmission may be dynamically or semi-statically indicated to the WTRU. For example, the WTRU may receive an implicit or explicit indication in a dynamic indication (e.g., DCI) that triggers the SRS transmission. The WTRU may start the SRS transmission from a predetermined link (e.g., the indicated link configured by the gNB associated with the primary TRP, etc.).

[0119] The WTRU may send an SRS to each TRP by using at least one of the following modes for setting the transmit power.

[0120] The WTRU may transmit SRS to all configured transmission points with equal power. In this mode, the WTRU may be configured with a single reference signal as a reference for path loss estimation. In one embodiment, the WTRU may or may not use the same beam for each SRS transmission event. For example, in one embodiment, the WTRU may receive a single reference signal as an uplink beam indication for transmission to all TRPs. In one embodiment, the WTRU may receive more than one reference signal as an uplink beam indication for multiple transmissions, where each transmission may be based on a different reference signal.

[0121] The WTRU may transmit the SRS with different powers to each configured transmission point. In this mode, the WTRU may be configured with multiple reference signals, each of which may be used as a reference for path loss estimation for different TRP links. In one embodiment, the WTRU may or may not use the same beam for each SRS transmission event. For example, the WTRU may receive a single reference signal as an uplink beam indication for transmission to all TRPs.

[0122] In one embodiment, the WTRU may receive more than one reference signal as an uplink beam indicator for multiple transmissions, where each transmission may be based on a different reference signal.

[0123] The WTRU may determine the transmission opportunities of SRS resources based on the pattern of active symbols or slots.

[0124] In one embodiment, the WTRU may receive a time-indexed skip pattern (in which SRS transmissions may be omitted) and an index of a target TRP for each time slot. Hereinafter, the use of time slots may be used interchangeably with "per symbol" or "per RB". This pattern may reduce interference at the target TRP because the WTRU may skip transmissions that may occur in the indicated time slots. For example, the WTRU may receive a pattern indicating ({time slot 1, TRP1}, {time slot 2, TRP2}). The WTRU may determine to transmit SRS resources in time slot 1 for any TRP other than TRP1, and similarly to transmit SRS resources in time slot 2 for any TRP other than TRP2. This may result in the WTRU having less interference at TRP1 in time slot 1 and less interference at TRP2 in time slot 2.

[0125] The pattern may be configured to avoid interference from all WTRUs served by one TRP. A group of WTRUs may receive an indication via a group-common DCI with, for example, a group-specific RNTI. For example, the pattern may be configured such that the WTRUs in group 1 served by TRP1 may send SRS only in timeslot 2 and not in timeslot 1. In the absence of interference from the WTRUs served by TRP1, the WTRUs in group 2 served by TRP2 may send SRS in timeslot 1 to TRP1 and TRP2 for the measurement assumption. The network may receive the SRS and determine the C-JT predecoder for the WTRUs in group 2 using TRP1 and TRP2.

[0126] More than one TRP can be configured in this mode so that timeslot 1 is TRP1, timeslot 2 is TRP2, and so on.

[0127] A pair of TRPs (eg, TRP1 and TRP2) may be indicated in one skipped slot so that the WTRU may omit any SRS transmission to TRP1 or TRP2.

[0128] This pattern may be specifically indicated by the WTRU to limit interference from the WTRU. For example, WTRU1 and WTRU2 may be served by TRP1, and WTRU1 may receive a skip indication. WTRU1 may transmit only in time slots except for the indicated skip pattern. WTRU2 may transmit SRS without interference from WTRU1.

[0129] The WTRU may determine the next valid uplink subframe for SRS transmission based on the pattern. For example, the WTRU may receive a pattern indicating to skip the next X time slots. The WTRU may transmit the SRS X time slots after receiving the indication. During the X time slots, the WTRU may omit transmission.

[0130] The WTRU may receive skip patterns dynamically. For example, a field in a grant (e.g., DCI, configured grant (CG)) may indicate a pre-configured pattern in a set of pre-configured patterns. The pattern may be indicated similarly to a slot format indicator (SFI) as having one or more skipped slots and one or more TRPs for each skipped slot. A skip pattern may be linked to one or more SFI patterns in an SFI pattern so that the skipped slots are mapped to DL, UL, or flexible (F) subframes that may be used as DL or UL. For example, SFI pattern 1 may all be uplink slots. The first two UL opportunities may be linked to TRP1, and the next two UL opportunities may be linked to TRP2. The WTRU may send SRS to TRP1 only in the first two UL opportunities (i.e., omitting SRS to TRP2), and may send SRS to TRP2 only in the next two UL opportunities (i.e., omitting SRS to TRP1).

[0131] More than one pattern set may be configured as part of the SRS resource set configuration, and one of the patterns in the set may be dynamically activated by a command or grant (e.g., DCI or MAC-CE). The mode may also be configured separately from the SRS configuration, and the WTRU may apply the mode to any UL transmission (e.g., PUCCH, PUSCH, CG). The WTRU may apply the pattern periodically according to the configured period. For example, a pattern may be repeated for X time slots every Y time slots. The WTRU may apply the pattern semi-persistently (SP). For example, the mode may be activated after a configurable threshold on the DCI and remain active for the next Z time slots. After the active period, the WTRU may resume the transmission of the SRS as configured without skipping time slots. The WTRU may receive a command (e.g., MAC-CE) to activate / deactivate the SP mode.

[0132] The WTRU may implicitly determine the skip rule based on the target TRP for each SRS. For example, a rule may be defined where TRP1 may have a higher priority than TRP2. If both SRS are configured / triggered to be transmitted on the same timeslot, the WTRU may determine to send SRS for TRP1 and omit SRS for TRP2.

[0133] The WTRU may select SRS parameters per TRP based on the activated TRP.

[0134] In one embodiment, the WTRU may determine that an SRS resource set or an SRS resource may include an index to a CMR group (e.g., a set of CSI-RS for downlink channel measurement). The WTRU may determine that an SRS resource set or an SRS resource is associated with a TRP through a CMR group association. For example, CMR group 1 may be associated with TRP1 and CMR group 2 may be associated with TRP2. The WTRU may be configured with more than one parameter set, and based on the association with the CMR group, the WTRU may select parameters for SRS transmission to a target TRP. The WTRU may receive an activation command through, for example, a grant or a MAC-CE. The WTRU may determine which CMR group (i.e., TRP) is activated for the SRS resource.

[0135] For example, the SRS resource set may be configured with one parameter set for CMR group 1 and another parameter set for CMR group 2. If CMR group 1 is active, the WTRU may select parameters for the SRS associated with CMR group 1. If CMR group 2 is active, the WTRU may select parameters for the SRS associated with CMR group 2. These parameters may include one or more of the following: cyclic shift (CS); comb; time offset; RPFS; frequency offset; base sequence index; sequence group index; or frequency hopping.

[0136] In one example, the WTRU may transmit SRS sequences with group hopping turned on, where group 1 may be associated with CMR group 1 and group 2 may be associated with CMR group 2. Similarly, with sequence hopping, the WTRU may select one sequence when transmitting to TRP1 and a second sequence when transmitting to TRP2.

[0137] The WTRU may receive a pair of active CMR groups that may correspond to TRPs coordinating C-JT. The WTRU may select parameters based on the pair of CMRs. For example, a WTRU served by TRP1 and TRP2 may determine to use the same base sequence for both TRPs, and the WTRU may use a different CS for each TRP. If different CMR groups are paired, the WTRU may select different base sequences.

[0138] In one example, the WTRU may select different parameters depending on the TRP pair configured for C-JT. For example, two CMR groups may be configured with SRS resources for TRP1 and TRP2 and a comb of 2. There may be two possible offsets for the comb: starting from RE1 or starting from RE2. The third TRP may be paired with TRP1 or TRP2, so that the WTRU may be in C-JT with TRP1 and TRP3 or TRP2 and TRP3. Depending on which TRP is paired with TRP3, the WTRU may select different offsets for the SRS resources. If the SRS resources are sent to TRP1, the WTRU may select an offset of 1 starting from RE1, and if the SRS is sent to TRP2, the WTRU may select an offset of 2 starting from RE2.

[0139] Similarly, in case of RPFS, the WTRU may select offset 1 from RB1 for TRP1 and offset 2 from RB2 for TRP2. Similarly, the time offset may be selected per TRP (e.g., OFDM symbol offset 1 for TRP1 and OFDM symbol offset 2 for TRP2).

[0140] In one embodiment, the WTRU may receive a time bundling configuration between multiple time slots, and each time slot may be associated with a CMR group (i.e., TRP). For example, the WTRU may receive a time bundling of two time slots and CMR group 1 associated with time slot 1 and CMR group 2 associated with time slot 2. The WTRU may determine to use one of the parameters (e.g., sequence index 1) in time slot 1 and a second parameter (e.g., sequence index 2) in time slot 2. The WTRU may transmit an SRS to a target TRP on each time slot in the bundle, using the parameters selected by the WTRU for each time slot.

[0141] In one embodiment, the WTRU may receive one or more configuration parameters including a configuration of a first SRS resource (targeted to a first TRP) and a configuration of a second SRS resource (targeted to a second TRP), wherein the WTRU may receive (e.g., based on the configuration of the second SRS resource or based on one or more configuration parameters) an indication that the second SRS resource is associated with the first SRS resource, for example with respect to mTRP operation (e.g., for mTRP channel acquisition / estimation, etc.) and / or with respect to a non-periodic SRS triggering mechanism.

[0142] In one example, the WTRU may receive, for example, via RRC signaling, a configuration of multiple aperiodic SRS triggering states (e.g., aperiodicSRS-resourceTriggerList or aperiodicSRS-resourceTrigger), wherein one or more of the multiple aperiodic SRS triggering states may be indicated / selected (e.g., activated via MAC-CE) to map to one or more code points of a field (e.g., SRS request field) of a DCI. The WTRU may receive an indication (e.g., configuration) that a first SRS triggering state of the multiple aperiodic SRS triggering states includes a first SRS resource (targeting a first TRP) but does not (explicitly) include a second SRS resource.

[0143] Based on determining that the first SRS resource is included in the first SRS triggering state and the first SRS resource has an association with the second SRS resource (for example, in terms of mTRP operation and / or non-periodic SRS triggering procedure), the WTRU may determine that a codepoint among one or more codepoints indicating the first SRS resource may indicate both the first SRS resource and the (associated) second SRS resource to be sent by the WTRU.

[0144] In one example, the indication by the code point that triggers the transmission of both the first SRS resource and the second SRS resource may be based on an (explicit) parameter value in the DCI (e.g., a one-bit parameter for switching mTRP parameters or a pre-configured mode / parameter) (e.g., indicating an mTRP mode, multiple SRS transmissions for mTRP operation, etc.), or based on an implicit indication associated with the value of an existing field in the DCI. In one example, based on determining the (explicit) parameter value or indicating otherwise by an implicit indication, the WTRU may only transmit the first SRS resource in response to receiving the DCI. This may reduce the signaling overhead in the non-periodic SRS triggering procedure and increase the flexibility and effectiveness of managing multiple non-periodic SRS resources triggered for mTRP channel acquisition / estimation.

[0145] At least one of the following may be applied (e.g., based on an indication / configuration from the gNB and / or based on a predefined / predetermined rule), wherein at least one of the following may be based on or involve the sending of both a first SRS resource and a (associated) second SRS resource (for mTRP channel acquisition).

[0146] The WTRU may receive a plurality of (SRS-related) parameters associated with an SRS resource set including one or more SRS resources (e.g., at least a first SRS resource and a second SRS resource), wherein the plurality of parameters may include N time domain offsets (e.g., one offset per TRP). The one offset per TRP may be applied relative to an SRS triggering DCI (e.g., a time instance at which the SRS triggering DCI is received).

[0147] The WTRU may receive a DCI including an SRS request field, wherein a code point of the SRS request field may indicate a first SRS triggering state including at least a first SRS resource (included in a set of SRS resources). In response to receiving the DCI, the WTRU may send the first SRS resource based on a first offset associated with a first TRP among the N time domain offsets, and send a second SRS resource (e.g., associated with the first SRS resource) based on a second offset associated with a second TRP among the N time domain offsets.

[0148] The WTRU may receive, for example, via RRC signaling, a plurality of combinations of SRS-related parameters (e.g., cyclic shift, comb value, sequence-related parameters such as sequence ID or group ID, port configuration, SRS power control parameters including path loss RS, etc.) for the first SRS resource and / or the second SRS resource. The WTRU may receive, for example, via MAC-CE, a subset of the plurality of combinations of the first SRS resource and / or the second SRS resource. The WTRU may receive, for example, via DCI, a dynamic trigger (e.g., based on a code point indicated by the DCI) of one or more of the plurality of combinations of SRS-related parameters for the first SRS resource and / or the second SRS resource or a subset of the plurality of combinations.

[0149] In one example, the DCI that triggers the transmission of at least one SRS resource may update SRS-related parameters of the SRS resource triggered by the DCI (e.g., cyclic shift, comb value, sequence-related parameters such as sequence ID or group ID, port configuration, SRS power control parameters, etc.), which may reduce control signaling overhead and latency because the DCI may update / change the SRS-related parameters of the SRS resource (e.g., instead of reconfiguring the update parameters via RRC).

[0150] In one example, the WTRU may expect (e.g., the gNB should ensure) that the DCI triggering the transmission of at least one SRS resource does not include a data scheduling assignment / grant (e.g., as an SRS triggering DCI with no data scheduling). This may provide benefits in terms of reducing control signaling overhead and latency based on more bit fields available in the DCI (without data), for example, to indicate the combination.

[0151] In one example, a different RNTI value (eg, an RNTI associated with an SRS configuration) may be used to receive the DCI.

[0152] In one example, the MAC-CE command may update SRS-related parameters of the SRS resources (e.g., cyclic shift, comb value, sequence-related parameters such as sequence ID or group ID, port configuration, SRS power control parameters, etc.), which may reduce control signaling overhead and latency because the MAC-CE may update / change the SRS-related parameters of the SRS resources (e.g., instead of reconfiguring the update parameters via RRC).

[0153] The WTRU may only expect that for an SRS resource (e.g., a first SRS resource or a second SRS resource), the same comb value is indicated by a dynamic trigger, which may reduce uplink interference based on avoiding / reducing frequency domain resource (e.g., RE) conflicts. In one example, the WTRU may expect (e.g., the gNB should ensure) that the parameters of the comb may not be included in multiple combinations of SRS-related parameters.

[0154] In one embodiment, the WTRU may send an SRS based on a non-periodic (A-SRS) trigger point (i.e., the SRS request field) using a parameter set associated with a TRP or a TRP group (e.g., TRP1 and TRP2). For example, the WTRU may receive a configuration of an SRS resource set with one SRS resource, and the SRS resource may be configured with multiple parameter sets. For example, the parameter set may include a parameter set, such as a power control parameter (e.g., path loss reference signal (PL-RS), α, P0), a spatial filter (e.g., SRI), a CS index, a comb offset, a frequency hopping pattern, a frequency offset / time offset, or a sequence index / group index. When the WTRU sends the SRS, one parameter set may be active. In order to determine which parameter set is active, the WTRU may receive an A-SRS configuration of code points, where each code point may be mapped to one of the parameter sets. For example, code point 1 may be mapped to CS index 1, and code point 2 may be mapped to CS index 2. The WTRU may receive a scheduling grant (eg, DCI) that may include an SRS request field codepoint, and the WTRU may activate a parameter set associated with the codepoint to send SRS resources.

[0155] The WTRU may determine the TRP-specific parameter set to be activated for A-SRS transmission based on the SRS resource set indicator field and the SRS request field. For dynamic switching between single TRP (STRP) and multiple TRP (mTRP) repetitive scheduling, the grant may include a 2-bit field, where, for example, 00 may indicate sTRP1, 01 may indicate sTRP2, and 10 and 11 may indicate mTRPs with repetitive ordering of TRP1-TRP2 or TRP2-TRP1, respectively. If the A-SRS resource is triggered and the SRS resource set indicator indicates sTRP1, the WTRU may send SRS using the first parameter set that is activated (e.g., associated with the PL-RS of TRP1). If the SRS resource set indicator indicates sTRP2, the WTRU may send SRS using the second parameter set that is activated (e.g., associated with the PL-RS of TRP2). If the SRS resource set indicator indicates TRP1-TRP2 or TRP2-TRP1, the WTRU may send the SRS using a parameter set configured for mTRP operation (e.g., C-JT). For example, the WTRU may be triggered to send the SRS using multiple parameter sets, where the first time slot may use the parameter set for TRP1 and the second time slot may use the parameter set for TRP2. The SRS resource set indicator may be extended with additional bits to enable triggering of multiple combinations of TRPs (e.g., TRP1-TRP2-TRP3, TRP1-TRP3, etc.). The TRP index associated with the SRS resource set indicator may be reconfigured, for example, via RRC signaling or MAC-CE. For example, the indicator may be associated with TRP1 / TRP2 / TRP1-TRP2 / TRP2-TRP1, or may be reconfigured to be associated with TRP1 / TRP3 / TRP2 / TRP1-TRP3.

[0156] The WTRU may determine the time slot for the A-SRS based on an RRC configured value of the number of time slots (n) after receiving the triggering DCI. The WTRU receives n as part of the SRS resource set configuration. The WTRU may receive an SRS offset indicator bit field in the grant, which may dynamically indicate an additional offset (e.g., k time slots) from the triggering DCI to the SRS transmission. A list of up to four offsets (e.g., k1, k2, k3, k4) may be RRC configured, and the DCI may dynamically indicate one of the values ​​from the list (e.g., k=k1). The WTRU may send the SRS in the (n+k)th time slot after the DCI.

[0157] For mTRP, it may be desirable for the network to trigger more than one SRS resource with different parameter configurations to target different TRPs. The WTRU may transmit multiple SRS to enable multiple TRPs to estimate different WTRU-TRP channels. Triggering multiple SRS with different dynamic offsets and configurations requires multiple DCIs indicating different dynamic offsets. This may result in higher PDCCH resource overhead since multiple DCIs are used for one WTRU to trigger multiple SRS.

[0158] In one embodiment, the WTRU may receive an SRS offset indicator code point bit field, where each code point may be mapped to or associated with one or more SRS offset values, and each offset code point or value may be associated with an SRS parameter set. The WTRU may be triggered to send the same SRS resource at multiple time offsets, with one parameter set activated for each time offset. A single trigger command may be sufficient.

[0159] Figure 3 An example method 300 of dynamic joint SRS configuration and offset triggering is shown. A WTRU may receive multiple SRS configurations 310. Each SRS configuration may be associated with parameters, and these parameters may be different. These parameters may include, for example, a cyclic shift (CS) and a path loss reference signal (PL_RS). For example, a first SRS configuration (config1) may include at least CS1; a second SRS configuration (config2) may include at least CS2; a third SRS configuration (config3) may include at least CS1; a fourth SRS configuration (config4) may include at least PL_RS1; and a fifth SRS configuration (config5) may include at least PL_RS2. The WTRU may receive a configuration of an SRS offset indicator code point bit field, where a code point may be associated with one or more SRS time offsets 320. For example, as Figure 4 As shown, code point bit field 00 is associated with a pair of offsets (k1, k2), and other code points 01, 10, and 11 are associated with single offset values ​​k3, k4, and k5, respectively. The WTRU may receive information 330 indicating an association between an SRS offset and an SRS configuration. For example, Figure 5As shown, offset k1 is associated with an SRS configuration with CS1 (config1), k2 is associated with an SRS configuration with CS2 (config2), k3 is associated with an SRS configuration with CS1 (config3), k4 is associated with an SRS configuration with PL_RS1 (config4), and k5 is associated with an SRS configuration with PL_RS2 (config5). Other parameter sets may be configured, such as PL_RS index, sequence index, comb index, frequency domain index, or other SRS parameters. Similar to config1, config3 uses CS1 and triggers only one SRS. config4 and config5 use different PL_RS to target different TRPs with different spatial filters. The WTRU may receive downlink control information (DCI) that may include an SRS request field 340 for triggering an SRS resource. The WTRU may determine an SRS offset indicator code point for the triggered SRS resource based on the SRS request field. The WTRU may determine parameters of the SRS resource based on the SRS offset. For example, the WTRU may receive code point 00 in a DCI indicating offset k1 and offset k2, such as Figure 4 The WTRU may send SRS resources 350 in the determined time slot or slots and using the determined SRS configuration or SRS configurations. For example, if the WTRU receives code point 00 in the DCI, the WTRU may send SRS resources in the (n+k1)th time slot using CS1 and may send SRS resources in the (n+k2)th time slot using CS2.

[0160] The configuration of the k value may be RRC configured or the WTRU may receive a MAC-CE to update or modify the k value associated with the SRS offset indicator code point. The RRC configuration or MAC-CE may also update or modify the parameter set configuration associated with each k value.

[0161] In one embodiment, the WTRU may receive two separate configurations of SRS offset indicator codepoint tables, where one table (i.e., Table 1) may have one offset per codepoint and a second enhanced (new) table (i.e., Table 2) may be configured with multiple offsets per codepoint. In Table 1, codepoint 00 may be associated with k1 using config1, while in Table 2, codepoint 00 may be associated with (k1, k2), such as Figure 3As shown. The WTRU may receive an indication (e.g., a new bit in the DCI) to switch between the two tables. For example, if the WTRU receives bit 0, the WTRU may use table 1 and the WTRU may send one SRS using config1. If the WTRU receives bit 1, the WTRU may use table 2 and send two SRS using (k1, k2) offsets and config1 and config2, respectively.

[0162] The WTRU may be triggered to send mTRP aperiodic SRS (AP-SRS) with dynamic parameter updates. Figure 6 An example method 600 for mTRP SRS transmission is shown. A WTRU may receive SRS resource configuration information 610. The SRS resource configuration information may include a configuration of one or more AP-SRS resources. The SRS resource configuration information may include a set of parameters for each AP-SRS resource. The set of parameters may include, for example, a cyclic shift (CS), a comb value, a sequence-related parameter such as a sequence ID or a group ID, a port configuration, a path loss reference signal (PL RS), and / or an SRS power control parameter. The WTRU may receive a command or indication 620 to trigger an AP-SRS. For example, the command or indication may be received in a DCI or a MAC-CE. The command or indication may indicate, for example, an AP-SRS resource, a first parameter for a first TRP (TRP1), and a second parameter for a second TRP (TRP2). The WTRU may send an AP-SRS to the TRP 630. The WTRU may send an AP-SRS to each TRP (e.g., TRP1 and TRP2) using the indicated AP-SRS resource and the indicated parameters for each respective TRP.

[0163] The WTRU may utilize dynamic multi-offset triggering associated with multiple parameters to send mTRP AP-SRS. Figure 7 An example method 700 of mTRP SRS transmission is shown. The WTRU may receive SRS configuration information 710. The SRS configuration information may indicate a configuration of multiple AP-SRS resources. Each AP-SRS resource may be associated with a TRP. The WTRU may receive information indicating an offset codepoint configuration 720. The codepoint may be associated with multiple time offsets. Each time offset may be associated with an AP-SRS resource. The WTRU may receive information (e.g., DCI) including the codepoint 730. The WTRU may send multiple SRS 740. Each SRS transmission may go to a different TRP and may be based on the time offset and the associated TRP.

[0164] Figure 8An example method 800 for mTRP SRS transmission is shown. A WTRU may receive an mTRP SRS resource configuration 810. The WTRU may receive the mTRP SRS resource configuration via RRC signaling. The mTRP resource configuration may include a set of SRS resources. The set of SRS resources may include one or more SRS resources (e.g., SRS1, SRS2). The set of SRS resources may include multiple path loss reference signals (PL RSs) (e.g., PLRS1, PLRS2, PLRS3). The mTRP resource configuration may include information indicating the association of at least two PL RSs with each SRS resource (e.g., SRS1 may be associated with PLRS1 and PLRS2; SRS2 may be associated with PLRS1 and PLRS3). The mTRP resource configuration may include a set of time-based mTRP patterns associated with the resource set (e.g., pattern 1, pattern 2, etc.). Each time instance (e.g., time slot) of each pattern may be associated with a TRP. Fig. 9Examples of two time-based modes are shown. Mode 1 indicates the use of SRS1 resources. Mode 1 indicates the use of the first time slot (time slot n) for sending SRS to TRP1 using SRS1 resources, the use of power control based on PLRS1, and the use of CS1. Mode 1 indicates the use of the second time slot (time slot n+1) for sending SRS to TRP2 using SRS1, the use of power control based on PLRS2, and the use of CS2. Mode 2 indicates the use of SRS2. Mode 2 indicates the use of the first time slot (time slot n) for sending SRS to TRP1 using SRS2 resources, the use of power control based on PLRS1, and the use of CS1. Mode 2 indicates the use of the second time slot (time slot n+1) for sending SRS to TRP3 using SRS2 resources, the use of power control based on PLRS3, and the use of CS3. The mTRP resource configuration may include one or more SRS parameters associated with each TRP or time instance. These parameters may be, for example, cyclic shift (CS), comb teeth, time offset, sequence index, and / or group index. The WTRU may receive a command or indication to activate a mode in a set of modes 820. The command may be received in a DCI or a MAC-CE. The WTRU may determine a mode to be activated from the set of modes. For example, the DCI may include a field indicating a mode in the set of modes. For example, the MAC-CE may include a command to activate a mode in the set of modes. The WTRU may send an SRS to a TRP based on the activated mode 830. The WTRU may send a first SRS in a first time instance using a first SRS resource from one or more SRS resources and a first SRS parameter from one or more SRS parameters. The first SRS resource and the first SRS parameter may be determined based on the activated time-based mode. The first SRS may be sent to a first TRP. The WTRU may send a second SRS in a second time instance different from the first time instance using the first SRS resource and the second SRS parameter. The second SRS parameter may be determined based on the activated time-based mode. The second SRS may be sent to a second TRP. For example, Fig.10 As shown, based on Fig. 9 In the modes, if Mode 1 is activated, the WTRU sends SRS to TRP1 using SRS1 resources in time slot n using power control based on PLRS1 and using cyclic shift CS1, and sends SRS to TRP2 using SRS1 resources in time slot n+1 using power control based on PLRS2 and using cyclic shift CS2. If Mode 2 is activated, the WTRU sends SRS to TRP1 using SRS2 resources in time slot n using power control based on PLRS1 and using cyclic shift CS1, and sends SRS to TRP3 using SRS2 resources in time slot n+1 using power control based on PLRS3 and using cyclic shift CS3.

[0165] Although the features and elements are described above in particular combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method for multiple transmit and receive point (mTRP) transmission implemented by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information indicating a sounding reference signal (SRS) resource set, the sounding reference signal (SRS) resource set comprising one or more SRS resources, one or more SRS parameters, and one or more time-based patterns; receiving an indication to activate a time-based mode of the one or more time-based modes; transmitting a first SRS in a first time instance using a first SRS resource of the one or more SRS resources and a first SRS parameter of the one or more SRS parameters, wherein the first SRS resource and the first SRS parameter are determined based on the activated time-based mode; as well as A second SRS is sent in a second time instance different from the first time instance using the first SRS resource and second SRS parameters, wherein the second SRS parameters are determined based on the activated time-based mode.

2. The method according to claim 1, wherein the configuration information further indicates a plurality of path loss reference signals (PL RS). 3 . The method of claim 2 , wherein the configuration information further indicates an association between each SRS resource and a corresponding subset of the plurality of PL RSs. 4 . The method of claim 2 , wherein the first SRS is transmitted using a transmission power determined based on a PL RS among the plurality of PL RSs, wherein the PL RS is determined based on the activated time-based mode. 5 . The method of claim 2 , wherein the second SRS is transmitted using a transmission power determined based on a PL RS among the plurality of PL RSs, wherein the PL RS is determined based on the activated time-based mode.

6. The method of claim 1, wherein the first SRS parameter and the second SRS parameter are a respective first cyclic shift (CS) and a second cyclic shift (CS), and the first CS and the second CS are different.

7. The method of claim 1, wherein the indication to activate the time-based mode is received in a downlink control information (DCI) or a medium access control (MAC) control element (CE).

8. The method according to claim 1, further comprising: A time-based mode to be activated is determined based on the indication to activate the time-based mode.

9. The method of claim 1, wherein the one or more SRS parameters include a cyclic shift, a comb, a time offset, a sequence index, or a group index.

10. The method of claim 1, wherein the first SRS parameter is based on the activated time-based mode and the first time instance, and the second SRS parameter is based on the activated time-based mode and the second time instance.

11. A wireless transmit / receive unit (WTRU), the wireless transmit / receive unit (WTRU) comprising: a receiver configured to receive configuration information indicating a sounding reference signal (SRS) resource set, the sounding reference signal (SRS) resource set comprising one or more SRS resources, one or more SRS parameters, and one or more time-based patterns; The receiver is further configured to receive an indication to activate a time-based mode of the one or more time-based modes; a transmitter configured to transmit a first SRS in a first time instance using a first SRS resource of the one or more SRS resources and a first SRS parameter of the one or more SRS parameters, wherein the first SRS resource and the first SRS parameter are determined based on the activated time-based mode; and The transmitter is further configured to transmit a second SRS in a second time instance different from the first time instance using the first SRS resource and second SRS parameters, wherein the second SRS parameters are determined based on the activated time-based mode.

12. The WTRU of claim 11, wherein the configuration information further indicates a plurality of path loss reference signals (PL RS).

13. The WTRU of claim 12, wherein the configuration information further indicates an association between each SRS resource and a corresponding subset of the plurality of PL RSs.

14. The WTRU of claim 12, wherein the first SRS is transmitted using a transmit power determined based on a PLRS among the plurality of PL RSs, wherein the PL RS is determined based on the activated time-based pattern.

15. The WTRU of claim 12, wherein the second SRS is transmitted using a transmit power determined based on a PLRS among the plurality of PL RSs, wherein the PL RS is determined based on the activated time-based pattern.

16. The WTRU of claim 11, wherein the first SRS parameter and the second SRS parameter are respective first and second cyclic shifts (CSs), and the first and second CSs are different.

17. The WTRU of claim 11, wherein the indication to activate the time-based mode is received in a downlink control information (DCI) or a medium access control (MAC) control element (CE).

18. The WTRU of claim 11 further comprising: A time-based mode to be activated is determined based on the indication to activate the time-based mode.

19. The WTRU of claim 11, wherein the one or more SRS parameters include a cyclic shift, a comb, a time offset, a sequence index, or a group index.

20. The WTRU of claim 11, wherein the first SRS parameter is based on the activated time-based mode and the first time instance, and the second SRS parameter is based on the activated time-based mode and the second time instance.

Images