Methods and procedures for bistatic and multistatic sensing

Abstract

A wireless transceiver / receiver unit configured to send a message to a network, such as a serving network, where the message indicates one or more channel state information (CSI) measurements supported by the WTRU, receive a plurality of reference signals (RSs), where each of the plurality of RSs is associated with a plurality of configured resource sets, determine, based on mutual information (MI) associated with the plurality of RSs, a respective sensing performance value for each of the configured resource sets associated with the plurality of RSs, determine a respective set of precoding matrix indicators (PMIs) for each of the configured resource sets based on the respective sensing performance value for each of the configured resource sets, and send a sensing report indicating the respective set of PMIs and the respective sensing performance value for each respective configured resource set of the configured resource sets.

Description

METHODS AND PROCEDURES FOR BISTATIC AND MULTISTATIC SENSINGCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of United States Provisional Application No. 63 / 518,908 filed on August 11 , 2023, the entire contents of which are incorporated herein by reference.BACKGROUND

[0002] Usually, sensing involves beam scanning procedures by the transmitter entity, where sweeping beams are generated to cover the targeted area in the environment (e.g., following a sequential order, and the receiver captures their reflections). In bistatic and multistatic sensing, a measurement entity (e.g., a wireless transceiver / receiver unit (WTRU)) must detect one or multiple signal copies reflected by the environment from one or multiple sensing beams and perform measurements (e.g., delay, power, angle of arrival (AoA), etc.) to identify the scatterers thereof. In monostatic sensing, the receiving entity is co-located with the transmitter. It performs detection simultaneously with transmission (e.g., in full duplex mode) or after the transmission is completed (e.g., in half duplex mode).

[0003] A bistatic or multistatic scenario may comprise one or more transmission reception points (TRPs) as transmitting entities for sensing in the downlink and one or multiple WTRUs as receivers to perform sensing measurements and report measurements back to the network. Similar bistatic or multistatic scenarios may involve two or more WTRUs, two or more base stations (BSs), and / or a transmitting WTRU and a receiving BS.SUMMARY

[0004] A wireless transceiver / receiver unit (WTRU) may comprise a processor. The processor may be configured to send a message to a network, such as a serving network. The message may indicate one or more channel state information (CSI) measurements supported by the WTRU. The processor may be configured to receive a plurality of reference signals (RSs), where each of the plurality of RSs is associated witha plurality of configured resource sets. The processor may be configured to determine, based on mutual information (Ml) associated with the plurality of RSs, a respective sensing performance value for each of the configured resource sets associated with the plurality of RSs. The sensing performance value may, for example, be a Minimum Mean Square Error (MMSE) or Mean Square Error (MSE) value that is below a threshold. For example, the sensing performance value of a configured resource set indicates a statistical error associated with a sensing metric being measured for the configured resource sets. In some examples, the Ml may be a metric characterizing an amount of information carried by a channel associated with each of the configured resources sets.

[0005] The processor may be configured to determine a respective set of precoding matrix indicators (PMIs) for each of the configured resource sets based on the respective sensing performance value for each of the configured resource sets. For example, the processor may be configured to determine the set of PMIs based on the sensing performance value for the configured resource set being within a predetermined range.

[0006] The processor may be configured to send a sensing report indicating the respective set of PMIs and the respective sensing performance value for each respective configured resource set of the configured resource sets. In some examples, the sensing report may be sensing codebook indexes per Channel State Information (CSI) RS Resource Indicator (CRI).

[0007] The processor may be configured to receive configuration information that includes spatial characteristics of the plurality of RSs.

[0008] The set of PMIs may be determined, for example, based on the sensing performance value for each respective configured resource set being within a predetermined range.

[0009] The message may be an indication of a supported performance metric for bistatic or multistatic sensing and / or a sensing codebook supported by the WTRU. The supported performance metric for bistatic or multistatic sensing may be any combination of (i) Minimum Mean Square Error (MMSE), (ii) Signal to Noise Ratio (SNR), (iii) Reference Signal Received Power (RSRP), (iv) Root Mean Square (RMS) error ofranging estimation, (v) RMS error of Angle of Arrival (AoA) estimation, (vi) RMS error of phase estimation, and / or (vii) RMS error of velocity estimation.

[0010] A WTRU may be configured to perform a method that includes one or more of the following steps. The method may include sending a message to a network, such as a serving network. The message may indicate one or more channel state information (CSI) measurements supported by the WTRU. The method may include receiving a plurality of reference signals (RSs), where each of the plurality of RSs is associated with a plurality of configured resource sets. The method may include determining, based on mutual information (Ml) associated with the plurality of RSs, a respective sensing performance value for each of the configured resource sets associated with the plurality of RSs. The sensing performance value may, for example, be a Minimum Mean Square Error (MMSE) or Mean Square Error (MSE) value that is below a threshold. For example, the sensing performance value of a configured resource set indicates a statistical error associated with a sensing metric being measured for the configured resource sets. In some examples, the Ml may be a metric characterizing an amount of information carried by a channel associated with each of the configured resources sets.

[0011] The method may include determining a respective set of precoding matrix indicators (PM Is) for each of the configured resource sets based on the respective sensing performance value for each of the configured resource sets. For example, the method may include determining the set of PMIs based on the sensing performance value for the configured resource set being within a predetermined range.

[0012] The method may include sending a sensing report indicating the respective set of PMIs and the respective sensing performance value for each respective configured resource set of the configured resource sets. In some examples, the sensing report may be sensing codebook indexes per Channel State Information (CSI) RS Resource Indicator (CRI).

[0013] The method may include receiving configuration information that includes spatial characteristics of the plurality of RSs.

[0014] The set of PMIs may be determined, for example, based on the sensing performance value for each respective configured resource set being within a predetermined range.

[0015] The message may be an indication of a supported performance metric for bistatic or multistatic sensing and / or a sensing codebook supported by the WTRU. The supported performance metric for bistatic or multistatic sensing may be any combination of: (i) Minimum Mean Square Error (MMSE), (ii) Signal to Noise Ratio (SNR), (iii) Reference Signal Received Power (RSRP), (iv) Root Mean Square (RMS) error of ranging estimation, (v) RMS error of Angle of Arrival (AoA) estimation, (vi) RMS error of phase estimation, and / or (vii) RMS error of velocity estimation.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A more detailed understanding may be had from the detailed description below, given by way of example in conjunction with drawings appended hereto. Figures in such drawings, like the detailed description, are examples. As such, the Figures (FIGs.) and the detailed description are not to be considered limiting, and other equally effective examples are possible and likely. Furthermore, like reference numerals ("ref.") in the FIGs. indicate like elements, and wherein:

[0017] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0018] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0019] FIG. 1 C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0020] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0021] FIG. 2 is a system diagram illustrating an example monostatic sensing scenario performed by a transmission reception point (TRP).

[0022] FIG. 3 is a system diagram illustrating an example bistatic sensing involving a TRP and multiple WTRUs.

[0023] FIG. 4 is a system diagram illustrating an example multistatic sensing involving a TRP and multiple WTRUs.

[0024] FIG. 5 is a system diagram illustrating an example of bistatic sensing involving sensing beams and sensing direction involving a TRP and a WTRU .

[0025] FIG. 6 is a system diagram illustrating an example scenario for bistatic sensing involving a TRP, a WTRU, and multiple scatterers.

[0026] FIG. 7 is a system diagram illustrating an example sensing CSI acquisition and reporting by a WTRU aided by RS for sensing CSI acquisition.

[0027] FIG. 8 is a flow diagram illustrating an example method for sensing CSI acquisition by a WTRU.

[0028] FIG. 9 illustrates a system diagram of an example bistatic sensing measurements performed by a WTRU aided by sensing RS over one or multiple active Transmission Configuration Indicator (TCI) states for sensing.

[0029] FIG. 10 is a flow chart diagram illustrating an example bistatic / multistatic sensing and reporting method by a WTRU.DETAILED DESCRIPTION

[0030] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components and circuits have not been described in detail, so as not to obscure the following description. Further, embodiments and examples not specifically described herein may be practiced in lieu of, or in combination with, the embodiments and other examples described, disclosed or otherwise provided explicitly, implicitly and / or inherently (collectively "provided") herein. Although various embodiments are described and / or claimed herein in which an apparatus, system, device, etc. and / or any element thereof carries out an operation, process, algorithm, function, etc. and / or any portion thereof, it is to be understood that any embodiments described and / or claimed herein assume that any apparatus, system, device, etc. and / or any element thereof isconfigured to carry out any operation, process, algorithm, function, etc. and / or any portion thereof.

[0031] The methods, apparatuses and systems provided herein are well-suited for communications involving both wired and wireless networks. An overview of various types of wireless devices and infrastructure is provided with respect to FIGs. 1A-1 D, where various elements of the network may utilize, perform, be arranged in accordance with and / or be adapted and / or configured for the methods, apparatuses and systems provided herein.

[0032] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0033] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated 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" and / or a "STA," may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription- based unit, a pager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head- mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU. Further, any description herein that is described with reference to a UE may be equally applicable to a WTRU (or vice versa). For example, a WTRU may be configured to perform any of the processes or procedures described herein as being performed by a UE (or vice versa).

[0034] The communications systems 100 may also include a base station 114a and / or a base station 11 b. 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 / 115, the Internet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, 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.

[0035] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in oneembodiment, the base station 114a may include three transceivers, i.e. , one for each sector of the cell. In an 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 transmit and / or receive signals in desired spatial directions.

[0036] 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).

[0037] More specifically, as noted above, the communications 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, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0038] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E- UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE -A Pro).

[0039] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access, which may establish the air interface 116 using New Radio (NR).

[0040] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interfaceutilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB).

[0041] 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), and the like.

[0042] The base station 114b in FIG. 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, 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 an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0043] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 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 shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing a NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E- UTRA, or WiFi radio technology.

[0044] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide 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), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications 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 / 113 or a different RAT.

[0045] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1 A 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.

[0046] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include 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 peripherals138, among others. It will be appreciated that the WTRU 102 may include any sub- combination of the foregoing elements while remaining consistent with an embodiment.

[0047] 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 in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0048] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0049] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, 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.

[0050] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that arereceived by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0051] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or 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 the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read- only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0052] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the 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, and the like.

[0053] 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 over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information byway of any suitable location-determination method while remaining consistent with an embodiment.

[0054] The processor 118 may further be coupled to other peripherals 138, which may include one or more software 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 e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0055] 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 particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half- duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0056] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an 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.

[0057] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0058] Each of the eNode-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, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0059] The CN 106 shown in FIG. 10 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0060] The MME 162 may be connected to each of the eNode-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, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0061] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the 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 user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0062] 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.

[0063] 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 communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves 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 the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0064] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0065] In representative embodiments, the other network 112 may be a WLAN.

[0066] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. The peer-to- peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11 e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using anIndependent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad-hoc" mode of communication.

[0067] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / 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.

[0068] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0069] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0070] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11 ah relative to those used in 802.11 n, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0071] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest 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, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0072] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0073] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0074] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 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, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an 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 unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0075] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or 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 gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0076] 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 the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a,160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0077] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0078] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0079] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 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 machine type communication (MTC) access, and / or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 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.

[0080] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0081] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an 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 downlink packets, providing mobility anchoring, and the like.

[0082] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network(DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0083] In view of Figures 1 A-1 D, and the corresponding description of Figures 1 A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0084] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may perform testing using over-the-air wireless communications.

[0085] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be testing equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0086] Methods and procedures for bistatic sensing and multi-static sensing using wireless signals in a cellular environment may be provided.

[0087] Sensing may refer to the estimation of one or more spatial characteristics (e g., the absolute or relative position, 3D orientation, speed, etc.) of one or multiple objects that are not wirelessly connected to the system under consideration. In some wireless systems, sensing may be considered part of the communication framework, for example, when considering integrated sensing and communications.

[0088] At least three sensing modes are commonly established depending on the relative positions of the transmitter and the receiver, or receivers, concerning the object to be sensed.

[0089] FIG. 2 is a system diagram 200 illustrating an example of monostatic sensing performed by a transmission reception point (TRP). Monostatic sensing refers to a scenario where the transmitter and receiver entities are co-located to estimate one or more of a position, a velocity, and / or an orientation of an object (e.g., an object). Monostatic sensing may be performed by a base station (BS) (e.g., a transmit-receive point (TRP)) or a WTRU. Sensing may be applied to detect one or multiple objects.

[0090] FIG. 3 is a system diagram 300 illustrating an example of bistatic sensing that includes a TRP and a WTRU. Bistatic sensing refers to a scenario where the transmitter and receiver entities are not co-located for sensing, with, for example, a TRP acting as a transmitter and a WTRU as a receiver (e.g., as shown), or vice versa.

[0091] FIG. 4 is a system diagram 400 illustrating an example of multistatic sensing including a TRP and multiple WTRUs. Multistatic sensing refers to a scenario where multiple receiving entities (e.g., the multiple WTRUs) sense one or multiple objects with the aid of a transmitting entity that is not co-located.

[0092] Monostatic sensing may require full duplex capabilities at the sensing entity (e.g., the WTRU or TRP), for example, the ability to simultaneously transmit a sensing signal and detect the reflections from the environment. Alternatively, monostatic sensing may be realized in half duplex mode by performing detection over a receive window that starts when the transmission is completed, for example, using detection techniques not based on Discrete Fourier Transforms (DFTs) that exploit only part of the reflected signals. Bistatic and multistatic sensing may be performed without using full duplex mode, as the transmitting and receiving entities are different.

[0093] Sensing schemes may also distinguish between active and passive sensing, depending on whether sensing involves transmitting an a-priori known signal and subsequent detection of reflected signals (e.g., in the active case), or whether it only involves detecting reflected signals (e.g., in the passive case). Methods and procedures described hereinafter generally refer to the active sensing case but can also be applied to passive sensing.

[0094] Channel State Information (CSI) may refer to a set of quantities that a communicating entity (e.g., a TRP or a WTRU) may obtain to characterize the channel state in any time, frequency, and / or spatial domain. CSI may be measured by the network and / or the WTRU to obtain the UL and DL channel states, respectively, and further optimize communications performance. CSI can be equal in UL and DL when channel reciprocity conditions hold, for example, in TDD systems using reciprocal transceiver architectures.

[0095] In some existing solutions, DL CSI may be measured by the WTRU with the aid of, for example, a set of CSI-RS signals or SS / PBCH blocks. As an example, an SS / PBCH block (SSB) may carry a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a Physical Broadcast Channel (PBCH), and / or a PBCH Demodulation Reference Signal (DMRS), all which can aid in determining the DL CSI. DL CSI information may include different measurement quantities, for example, RSRP, CQI, PMI, Rl, etc., as configured by the network in wideband or per sub-band mode.

[0096] UL CSI can be measured by the network with the aid of, for example, a Sounding Reference Signal (SRS), and / or US CSI can be obtained in the DL by the WTRU and reported back to the base station if channel reciprocity conditions hold. UL CSI may include similar measurement quantities as DL CSI. For example, UL CSI may include RSRP, CQI, PMI, Rl, and / or the like.

[0097] FIG. 5 is a system diagram 500 illustrating an example sensing scenario showing sensing beams and sensing direction for bistatic sensing. When scanning the medium for bistatic or multistatic sensing, some sensing beams may not successfully reach the intended targets (e.g., the object). For example, some sensing beams may not successfully reach the intended targets when beams are steered in directions that donot exhibit any meaningful object or are too far to be detected. The resources and / or energy spent by the sensing transmissions may be wasted in useless sensing attempts if no hint is provided about optimal beam configurations and / or directions to sense the medium.

[0098] A WTRU may help the network configure and / or refine beams for optimal directions for bistatic and multistatic sensing. The WTRU may report relevant data, for example, to help optimize the sensing procedure. One or more methods and procedures may be provided for bistatic and multistatic sensing using wireless signals in a cellular environment.

[0099] A “TRP” may be used interchangeably herein with “gNB”.

[0100] A “target”, a “scatterer” and an “object” may be used interchangeably herein to refer to any obstacle intended to be sensed that is not wirelessly connected to the system under consideration.

[0101] A “sensing beam” may be used herein to refer to the spatial domain filter used for the transmission or reception of a sensing reference signal.

[0102] A “sensing RS” may be used herein to refer to any reference signal for bistatic or multistatic sensing.

[0103] A “sensing CSI” may be used herein to refer to any channel measurements obtained by the receiving entity from the combined channel comprising the transmitter, the object and the receiver, that can be leveraged for sensing.

[0104] A “sensing PMI” may be used herein to refer to an indication of a precoding matrix for sensing, e.g., an index in a codebook of pre-defined precoding matrices that represent discretized directions for sensing. Sensing PMI can be part of a sensing CSI acquisition process performed by, e.g., the UE.

[0105] A “codebook of precoding matrices for sensing”, or “codebook for sensing”, may be used herein to refer to any set of precoding matrices for transmission of a sensing RS along a set of pre-defined directions.

[0106] A “RS for sensing CSI acquisition” may be used herein to refer to any RS used to acquire sensing CSI information. Without loss of generality, it will be assumed that it is an N-port signal, i.e. , it enables sensing CSI acquisition of up to N antenna ports.

[0107] “Sensing TCI states” and “TCI states for sensing” may be used interchangeably herein to refer to a set of Quasi-Colocation (QCL) relationships between a sensing RS and a RS for sensing CSI acquisition corresponding to the sensing beams.

[0108] A “MPC” may be used herein to refer to any of the multipath components that are received by, e.g., the UE, when detecting the scattered and reflected signals from the environment.

[0109] “Port”, and “antenna port”, may be used herein to refer to any signal whose channel characteristics can be unambiguously determined by a receiver with the aid of any suitable RS. Signals mapped to an antenna port may be transmitted by one or multiple physical antennas.

[0110] FIG. 6 is a system diagram 600 illustrating an example scenario for bistatic sensing using a TRP, a WTRU , and multiple scatterers. A cellular scenario is considered where one or multiple TRPs are aimed to sense the environment with the help of one or multiple WTRUs, that perform sensing measurements to derive spatial information about the surrounding objects, for example, their location, speed, orientation, etc., as determined by the system or the application.

[0111] A TRP may comprise any number of transmit-receive antennas, such as in a Massive Multiple Input - Multiple Output (M-MIMO) configuration. A number N of antenna ports may be signaled to the WTRUs as part of the sensing configuration, corresponding to the maximum number of antenna ports available for transmission of a sensing RS signal, a sensing RS for CSI acquisition signal, or both. WTRUs may be equipped with one or multiple receive antennas.

[0112] A suitable RS may already exist for sensing measurements, either in the form of an existing signal that is re-purposed for sensing, such as the DL Positioning Reference Signal (PRS) or the UL Sounding Reference Signal for Positioning (SRSp) in 5G NR, or a dedicated sensing signal. A suitable RS may already exist for sensing CSI acquisition, such as CSI-RS, SSB, or any other signal.

[0113] A signal waveform susceptible to frequency-domain analysis may be applicable. For example, an OFDM-like waveform, like CP-OFDM or DFT-s-OFDM, comprising discrete samples in the time or frequency domain may be applicable. Other waveforms may be similarly applicable.

[0114] Bistatic and multistatic sensing may be optimized by dynamically selecting one or more directions that yield the best possible sensing performance (e.g., the sensing accuracy expressed by its MMSE) and / or discarding one or more directions not best suited for sensing.

[0115] Measurement of sensing CSI information may be implemented.

[0116] Channel metrics for sensing that may help determine the spatial directions with the best possible sensing performance in bistatic or multistatic scenarios. These channel metrics may be denoted as sensing CSI or sensing CSI information.

[0117] Measurement of sensing CSI by the WTRU and selection of the spatial directions are performed to yield the least possible MMSE of the magnitude(s) to be sensed (e.g., the delays, AoAs, etc.). Other criteria may be equally valid for the measurement and reporting of sensing CSI information by the WTRU.

[0118] The spatial directions for sensing may be discretized and signalled as an index in a codebook for sensing (e.g., by means of a sensing PMI). The term "sensing PMI" will be used in this description, but any other naming convention may apply.

[0119] A relational link between the Mutual Information (Ml) attainable by a given channel and the MMSE of the parameter being estimated may be expressed by Equation (1 ) below:where the left-hand expression denotes the derivative with respect to the SNR; MMSE is the minimum MSE of the magnitude to be sensed; and Ml is the mutual information between the channel's input and output in the presence of additive white Gaussian noise (AWGN). Equation (1 ) holds regardless of the statistics of the input signal fed into the channel. Ml may also be a metric characterizing an amount of information carried by a channel associated with each of the configured resources sets.

[0120] In some solutions, Equation (1 ) may be used as a basis to identify the beams and spatial directions that exhibit an MMSE for sensing (e.g., which may be referred to as sensing MMSE) below a threshold, εmax, therefore representing the most suitable directions for sensing, as shown in Equation (2) below:MMSE < εmax. (2).

[0121] Different criteria other than the sensing MMSE may be used to select the most appropriate directions for sensing.

[0122] A pre-defined set of sensing beams may be assumed. These sensing beams may be identified by suitable indexes, including an identifier for a resource set in 5G NR, such as the CSI-RS Resource Indicator (CRI) or any other direct or indirect means. Moreover, a codebook of precoding matrices for sensing may be a-priori, whose entries are identified by codebook indexes denoted by a sensing PMI. The codebook may represent a set of precoding matrices for transmission of a sensing signal along any of a set of pre-defined directions for sensing.

[0123] FIG. 7 is a system diagram 700 illustrating an example of sensing CSI acquisition and reporting by a WTRU aided by RS for sensing CSI acquisition. In FIG. 7, several sensing beams, including suitable RS for sensing CSI acquisition, are used by a WTRU to derive the sensing MMSE with the help of Equation (1 ). The receiver (e.g., the WTRU) may select a set of suitable sensing beams and codebook indexes for sensing that satisfy Equation (2). The beams may be identified by means of their CRI, as in 5G NR, but any other identifier would be equally valid.

[0124] Sensing Precoding Matrix Indicator (PMI) values may be measured from one or several sensing beams transmitted by a TRP or other device. One or multiple sensing PMI values may be obtained per each sensing beam. For example, an association between sensing beams and sensing PMI values may be reported as a set of sensing PMI values within a given CRI that exhibit an MMSE below the threshold. For example, no sensing PMI value may be associated with a given CRI if their MMSE is above the threshold or if MMSE could not be obtained because of a low SNR or insufficient variation of the SNR necessary to compute the derivative of Ml reliably.

[0125] The obtained sensing PMI values corresponding to one or several sensing beams may be reported by the WTRU as part of a sensing report including channel measurements for sensing.

[0126] A sensing MMSE value may be calculated from the derivative of the mutual information with respect to snr according to Equation (1 ), irrespective of whether the channel is of AWGN or Rayleigh type.

[0127] Assuming a received constellation symbol y subject to AWGN with variance2, located in the complex plane at distanceswith respect to a set M constellation symbols xtin M-QAM modulation, the Ml may be obtained using Equation (3) below:

[0128] where denotes the expectation operator with respect to the symbol y conditioned to the known coordinates of xiand LLRxidenotes the log-likelihood ratios of transmission of xiversus transmission of any other symbol, which may be given by Equation (4) below:

[0129] LLR values may be computed by the WTRU through the application of Equation (4) or via lookup tables that approximate Equation (4) for each modulation order M, based on the parameter di / 2.

[0130] Symbols may experience a frequency-flat channel response, and Equations (3) and (4) may be straightforwardly applied. Alternatively or additionally, symbols may experience the effects of a Rayleigh fading channel whereby the frequency characteristics of the transmitted signal do not hold, and the received signal may exhibit a frequency-selective response. LLR calculation may be performed after channel equalization to restore the frequency characteristics of the signal. The detected signals after equalization may be considered subject to AWGN, whose noise power may be given by the sum of the thermal noise and the impairments resulting from the equalization process, including transceiver imperfections, such as phase noise, non- linearities, l / Q imbalances, and / or others, that add up to the combined noise power. In such cases, the values of SNR and a2after equalization (e.g., sometimes called the post-detection values) may be considered for Equation (4).

[0131] LLR calculations are reciprocal in UL and DL, for example, in time-division duplex (TDD) systems where the same frequency is used in the UL and the DL. Suppose system transceivers are designed to have reciprocal responses (e.g., their behaviour can be considered the same in UL and DL). In that case, the channel state may be identical in UL and DL, and so may be the LLR values. In other cases, such as infrequency-division duplex (FDD) systems, frequencies may differ for UL and DL, and the channel states may be different for UL and DL, making their LLR calculations non- reciprocal.

[0132] Ml may be obtained after multiplying the equalized received signal vector R, where N is the number of antenna ports for transmission of RS for sensing CSI acquisition, by one of the precoding matrices for sensingthus yielding a received signalThe distances between the received signal and the M ideally transmitted constellation symbols, {dk, 1 ≤ k ≤ M, k i}, may be further calculated and inserted into Equation (4) to obtain the LLRX. values that are inputted into Equation (3).

[0133] The snr after equalization may not be considered constant across frequency, such as when the channel frequency response is not constant across the RS resources for sensing CSI acquisition. The derivative of Ml with respect to snr may be approximated from a set of P different SNR values of the form {snr + (Δsnr)j,j = 1, ... , P}, where (Δsnr)jrepresents a small deviation around a given snr, by using Equation (5) below:where ( MI)jdenotes the j-th variation in Ml that result after a given snr variation (Δsnr)j.

[0134] The derivative of Ml with respect to snr may be obtained from the expression in Equation (6) below:where snreffrepresents the SNR of an equivalent Gaussian channel that yields the same Ml as the actual instantaneous channel. The value of snreffmay be obtained through link-to-system methods, such as Mutual Information Effective SINR Mapping (MIESM) and other methods. MIESM may provide the SNR of an ideal Gaussian channel with the same Ml as the actual instantaneous channel. Given that snreffmay beobtained as a function of snr, its derivative may also be obtained from Equation (6) as a function of snr.

[0135] Link-to-system methods may derive an expression for snreffbased on Equation (7) below:where I(x) is a function used to predict BLER (e.g., the Ml or a different one), and a2are implementation-specific model parameters that are adjusted to minimize the error between the BLER predicted by the model and the actual BLER at the modulation orders and coding rates of relevance for the system.

[0136] The derivative of Ml with respect to snr for channels with a varying response across frequency may be obtained by computing Ml over a vector Gaussian channel. The mutual information, in this case, may be more complex to obtain than in Equation (3).

[0137] The receiver (e.g., a WTRU) may be configured to measure the sub-band sensing PMI values based on the MMSE criterion in Equation (2) that correspond to a set of sub-bands, each comprising a subset of the user allocated bandwidth or a subset of the system bandwidth. The receiver may be configured to measure a wideband sensing PMI value based on wideband MMSE that corresponds to a pre-defined frequency region, including the user allocated bandwidth and / or the system bandwidth.

[0138] A sub-band sensing MMSE value may be derived from Equation (1 ) for a given sub-band size, including a frequency region spanning a subset of the frequency resources allocated for sensing CSI acquisition. As an example, the frequency resources of the RS for sensing CSI acquisition may be sub-divided into J non- overlapping sub-bands (with J > 2) in such a way that the frequency response of the channel at each sub-band may be considered constant, and suitable sensing MMSE values may be obtained per sub-band according to Equation (1 ). A fine granularity of sub-band sensing MMSE values may be leveraged for better allocation of sensing RS resources to meet a given maximum MMSE, emax.

[0139] In contrast, a wideband sensing MMSE value may be derived for a wider range of frequencies allocated to the RS for sensing CSI acquisition, including the userallocated bandwidth and / or the system bandwidth. The receiver (e.g., a WTRU ) may be configured to report a wideband sensing MMSE. In some solutions, the wideband sensing MMSE value may be obtained based on an effective SNR that yields the same Ml as the actual channel for the current device, for example, as in Equation (6). In some examples, the wideband sensing MMSE value may be obtained by means of the derivative of the mutual information of the vector channel that results from considering the channels at the J sub-bands.

[0140] The receiver may be configured to report a single wideband sensing MMSE that is computed as the maximum of the J individual sub-band sensing MMSE values, as shown in Equation (8) below:MMSEwb= max(MMSEn, l ≤ n ≤J} (8).

[0141] The receiver may be configured to report a single wideband sensing MMSE value that is equal to an average of the sub-band sensing MMSE values, including arithmetic mean as shown in Equation (9):

[0142] This approach may be generalized by considering a geometric mean, a harmonic mean, or any other analogous average function, to the expression in Equation (7) after replacing / ( ) with MMSE.

[0143] Other similar approaches may also be considered for obtaining wideband or sub- band PM I values based on the value of MMSE or any other suitable metric according to the implementation.

[0144] Sub-band or wideband precoding matrices for sensing may be obtained for a multiplicity of sensing directions that may be pre-defined, representing suitable spatial directions for sensing.

[0145] A codebook of precoding matrices for sensing may be a-priori defined that represents a set of spatial directions for sensing in one or multiple sensing beams.

[0146] A codebook may include a set of N precoding matrices (e.g., of the type defined for one-layer sensing transmissions. Each precodingmatrix may include the complex coefficients to be applied to the antenna ports to yield an / V-port sensing transmit signal effectively steered towards a desired spatial direction.The elements of the sensing codebook may be referred to as an index (e.g., a sensing PM I) whose selected values may be associated with one or several beams by means of a suitable indicator (e.g., a CRI value).

[0147] Codebooks for sensing may be based on a codebook defined for communication purposes (e.g., a codebook including precoding matrices for MIMO transmission) or based on a new codebook for sensing.

[0148] The receiver (e.g., the WTRU ) may receive one or multiple sensing beams. The equalized received signal vector for any of the received beams in the k-th subcarrier may be denoted as {Rk}, withand the index k running over the set of subcarriers allocated for sensing. The equalized received signal vector at each of the received beams may be multiplied by one or more (e.g., all) entries in the codebook thus yielding a received signal at the k-th subcarrierFrom these signals, the receiver may derive one or multipleprecoding vectors for sensing per each of the sensing beams in wideband or sub-band form based on the sensing MMSE criterion or any other.

[0149] The actual precoding matrix used by the transmitter for sensing may or may not be based on the sensing CSI feedback, which can be used by the transmitter just as non-limiting feedback information. Moreover, the precoding matrices used for transmission may be non-specified and transparent to the receiver and may or may not be based on the reported PM I values.

[0150] Methods and procedures for the acquisition and reporting of sensing CSI information that may be used by a transmitter entity to optimize sensing performance in bistatic or multistatic scenarios may be implemented.

[0151] The receiver (e.g., WTRU) may send a message, such as a capabilities information message, to the TRP upon initial access to the system. The message may include information about the WTRU's support of sensing CSI measurements and reports. For example, the message may indicate one or more CSI measurements supported by the WTRU. This message may be sent upon initial registration and can be sent via an uplink control or shared channel.

[0152] The information included in the capabilities message may include at least one of (i) the supported performance metrics for bistatic / multistatic sensing, (ii) sensingcodebook(s) supported by the WTRU (e.g., indicated via an index in a pre-defined table), and / or (iii) reported sensing CSI measurements. The supported performance metrics for bistatic / multistatic sensing may include at least one of (a) sensing MMSE, (b) SNR, (c) RSRP, (d) RMS error of ranging (or delay) estimation, (e) RMS error of AoA estimation, and / or (f) RMS error of velocity estimation.

[0153] The reported sensing CSI measurements may include at least one of (a) sensing codebook entries per each resource set (e.g., in the form of sensing PMI value(s)), (b) RSRP, post-detection SNR, or both values per each sensing codebook entry, (c) sensing MMSE values per each sensing codebook entry, (d) whether sub-band, wideband, or both reporting modes are supported for any of the above quantities, and / or (e) criteria for reporting wideband measurements (e.g., if requested) from the obtained sub-band measurements.

[0154] The criteria for reporting wideband measurements from the obtained sub-band measurements may include at least one of (A) maximum, minimum, or average (e.g., arithmetic mean, geometric mean, etc.) of the sub-band values, (B) a wideband value obtained from an equivalent AWGN channel that yields the same error performance (e.g., same hypothetical BLER) as the actual channel, and / or (C) a wideband value obtained for the vector Gaussian channel that results from considering the actual channel responses at the J sub-bands.

[0155] The WTRU may be configured, indicated, or determined to measure and report sensing CSI. For example, a WTRU may be configured with information about the spatial characteristics of the sensing beams (e.g., through RRC IE, DCI signalling, MAC CE, etc.). A first set of RS for sensing CSI acquisition may be used to denote the RS aimed to enable sensing CSI measurements by the WTRU, and a second set of sensing RS will be used to denote the RS aimed to enable bistatic or multistatic sensing measurements by the WTRU.

[0156] For example, the WTRU may obtain configuration information about the sensing beams by means of spatial relationships between a first set of RS for sensing CSI acquisition and a second set of sensing RS (e.g., as QCL characteristics). Spatial characteristics may specify which channel quantities may be common in the sensing RS and the RS for sensing CSI acquisition (e g., their delay spread, average delay, Dopplerspread, Doppler shift, Rx spatial filter, etc.). These can be, for example, explicitly defined or a reference to a set of pre-defined associations (e.g., in the form of TCI states for sensing). Different subsets of TCI states may be defined corresponding to beams with different beamwidths, including some having wide beamwidths while others having narrow beamwidths. Narrow beams may be more suitable for bistatic and multistatic sensing in view of their better angular resolution. In contrast, wide beams may be better suited for sensing CSI acquisition by the WTRU over a wider area with potentially multiple scatterers.

[0157] In some examples, the WTRU may obtain configuration information about the physical characteristics of the sensing beams, including any of the angular orientations, such as azimuth and elevation, Euler rotation angles, and / or any other angular metrics referred to an absolute or relative coordinate system, and / or beamwidths (e.g., in H, or both planes).

[0158] In some examples, the WTRU may be configured to measure and report sensing CSI information by means of any of an RRC IE, DCI signalling, and / or MAC CE.Sensing CSI information may be reported in the form of a wideband value or a collection of sub-band values. In the wideband case, the network may configure criteria for obtaining a wideband value (e.g., based on the maxima, minima, average, etc.).

[0159] Sensing CSI configuration information may comprise at least one of the (i) a first set of RS for sensing CSI acquisition, transmitted in a periodic, aperiodic, or semi- persistent form, (ii) sensing performance metric(s) and their allowed ranges to select the best precoding matrix indexes in a sensing codebook (e.g., sensing MMSE below a threshold), indicated as absolute or relative values, an index to a pre-defined table, etc., and / or (iii) information about the sensing CSI report.

[0160] The first set of RS for sensing CSI acquisition may be defined by (a) signals for sensing CSI measurements (e.g., SSB, CSI-RS, etc.), (b) number of ports N per sensing beam, (c) sensing resource sets used for sensing CSI acquisition, specified (e.g., as a list of resource set identifiers, an index to a table of resource set combinations, etc.), and / or (d) start RE, number of RBs, symbol and slot number, comb size and comb offset specified per each resource set, and / or globally if no resource setsare defined, and in case of a periodic or semi-periodic RS for sensing CSI acquisition, the periodicity of REs in number of slots, frames, time duration, etc.

[0161] The signals for sensing CSI measurements, for example, may be SSB signals used despite their limited spatial granularity and periodicity. In some examples, sparse signals for CSI measurements might be adapted for sensing (e.g., CSI-RS.). In some examples, a dedicated RS might be used for measurements.

[0162] The number of ports N per sensing beam, for example, may be equal to the number of entries in the sensing codebook.

[0163] The information about the sensing CSI report may include at least one of (A) an indication of whether sensing CSI reports are aperiodic, periodic, or semi-persistent, and the periodicity (e.g., in the number of slots, time duration, etc.) in the two latter cases and / or (B) an indication of whether wideband or sub-band reporting CSI is expected. The indication of whether wideband or sub-band reporting CSI is expected may include at least one of (1 ) the number of sub-bands J, as a value or an index to a table of pre-defined values, (2) the sub-band size, specified (e.g., as number of RBs, number of subcarriers, frequency range, an index to a table of pre-defined sub-band sizes, etc.), and / or (3) criteria for obtaining a wideband performance metric from a set of sub-band values.

[0164] The criteria for obtaining a wideband performance metric from a set of sub-band values may include at least one of (1) maximum, minimum, or average (e.g., arithmetic mean, geometric mean, harmonic mean, etc.) of the J sub-band values, (2) a wideband metric of an equivalent AWGN channel that yields the same error performance (e.g., hypothetical BLER) as the actual channel, and / or (3) a wideband metric of the vector Gaussian channel that results from considering the actual channel responses at the J sub-bands.

[0165] Some wideband performance values (e.g., the sensing MMSE) may be related to Ml (e.g., through Equation (1 )). An equivalent AWGN channel may be defined to yield the same hypothetical BLER as the actual channel, thus the same Ml, in order to derive a wideband MMSE. A wideband value may be established as (e.g., the arithmetic mean, geometric mean, or harmonic mean) of the individual sub-band values. Other similar criteria may be followed to obtain a wideband performance.

[0166] The WTRU may receive a plurality of RSs (e g., where each of the plurality of RS is associated with a configured resource set). For example, the WTRU may receive a first set of RS for sensing CSI acquisition per the sensing configuration, in the form of, for example, an SSB, CSI-RS, PRS, a dedicated RS for sensing, etc. Having received a first set of RS, the WTRU may perform at least one of multiple actions.

[0167] The WTRU may obtain the channel responses at the one or more configured resource sets by, for example, removing the known values of the RS complex symbols.

[0168] The WTRU may remove the effect of the channel responses by, for example, applying an equalizer to restore the frequency contents of the signals, thus obtaining the equalized RS symbols and the frequency-dependent post-detection SNR values at the one or more configured resource sets.

[0169] The WTRU may multiply the equalized RS symbols by each of the N precoding matrices in a sensing codebook to yield N frequency-dependent precoded signal vectors.

[0170] The WTRU may determine, based on mutual information (Ml) associated with the plurality of RSs, a sensing performance value for each of the configured resource sets associated with the plurality of RSs. For example, in the case of sub-band reporting by the WTRU, the WTRU may obtain the configured sensing performance value, such as sensing MMSE, for each precoded signal vector at the configured sub-bands and resource sets. The sensing MMSE may be obtained, for example, as two times the derivative of Ml with respect to the post-detection SNR. The derivative of Ml may be approximated, for example, as the ratio of a Ml variation that results from a measured variation in post-detection SNR. This approximation may be accurate if, for example, the SNR variation exceeds a pre-configured or fixed threshold, which, when not exceeded, may be reported to the TRP as a failure to obtain sensing MMSE.

[0171] In the case of wideband reporting, the WTRU may obtain a single wideband sensing performance metric for the intended frequency allocation per each precoded signal vector and configured resource set. The performance set and configured resource set may be based on the average value (e.g., arithmetic mean, geometric mean, harmonic mean, etc.) of the J sub-band performance values. The performance set and configured resource set may be based on the maximum or minimum of the Jsub-band performance values. The performance set and configured resource set may be based on the performance metric of an effective AWGN channel that would yield the same error performance as the actual channel (e.g., the same hypothetical BLER). The performance set and configured resource set may be based on the performance metric of the vector Gaussian channel that results from considering the actual channel responses at the J sub-bands.

[0172] The WTRU may compare the obtained performance values with a configured range (e.g., one or more thresholds to compare their values) per the configuration and may determine a set of codebook entries (e.g., sensing PMIs) per sensing resource set that fulfill a condition. These conditions may include PMIs whose sensing performance values are within a specified range (e.g., sensing MMSE below a threshold) and / or PMIs whose RSRP or post-detection SNR values are above a threshold. As such, the WTRU may determine a set of PMIs for each of the configured resource sets based on the sensing performance value for the configured resource sets.

[0173] The WTRU may send a sensing CSI report (e.g., over an uplink data or control channel). The sensing CSI report may indicate the determined set of PMIs and the sensing performance value for each of the configured resource sets. For example, the sensing CSI report may include the set of sensing codebook entries per resource set whose sensing performance fulfils the conditions set in the previous step, in wideband or per sub-band form. The sensing CSI report may include their corresponding post- detection SNRs and sensing MMSE values. The sensing CSI report may include an indication for those resource sets whose sensing codebook entries could not be obtained because, for example, of low SNR and / or insufficient SNR variation to reliably compute sensing MMSE.

[0174] FIG. 8 is a flow diagram for an example method 800 for sensing CSI acquisition by a WTRU . The method 800 may be performed by any combination of a processor, memory, and transceiver of the WTRU. It should be appreciated that the example sensing CSI acquisition method 800 may include one or more of the following. At 802, a WTRU may send a capabilities information message on the supporting sensing CSI measurements. For example, the WTRU may send a message to a network thatindicates one or more CS) measurements supported by the WTRU (e.g., as described herein).

[0175] At 804, the WTRU may receive configuration information about the spatial characteristics of the sensing beams and the measurement and reporting of sensing CSI. For example, the WTRU may be configured to measure and report sensing CSI over a set of sensing TCI states including a first set of RS for sensing CSI acquisition, defined by the signal type, number of ports, resource sets, periodicity, etc., sensing performance metric to select sensing PMIs, e.g., sensing MMSE, post-detection SNR, RSRP, etc., and / or information about the sensing CSI report, e.g., contents, periodicity, wideband / sub-band reporting mode, etc.

[0176] At 806, the WTRU may receive a first set of RSs for sensing CSI acquisition and may obtain channel responses at the resource sets. For example, the WTRU may receive a plurality of RSs (e.g., where each of the plurality of RS may be associated with a configured resource set). The WTRU may receive a first set of RS for sensing CSI acquisition over one or more resource sets and obtains sensing CSI information via at least one of the following steps. The WTRU may estimate the channel responses and obtain equalized RS symbols and their post-detection SNRs. The WTRU may multiply the equalized RS symbols with the set of precoding matrices included in a sensing codebook.

[0177] At 808, the WTRU may obtain equalized RS symbols, for example, by removing the effect of the channel and multiplying them by N precoding matrices (e.g., included in a sensing codebook).

[0178] At 810, the WTRU may obtain a wideband / sub-band sensing performance value for each precoded signal vector and resource set. The WTRU may obtain wideband or sub-band sensing performance values for each precoding vector and resource set wherein wideband values may be obtained according to any of an average, maximum, minimum, etc. of the sub-band individual values, an effective AWGN channel with the same hypothetical BLER performance as the actual channel, and / or a wideband value corresponding to the vector Gaussian channel that results from considering the actual channel responses at the sub-bands. In some examples, the WTRU may determine,based on Ml associated with the RSs, the sensing performance value for the configured resource sets (e.g., each of the configured resource sets) associated with the RSs.

[0179] At 812, the WTRU may determine the set of codebook entries with sensing performance within a specified range and / or with a sensing MMSE below a threshold. The WTRU may compare the sensing performance values with a specified range (e.g., MMSE below a threshold) and determines the subset of sensing PMI values that meet the performance criteria per each resource set. As such, the WTRU may determine a set of PMIs for the configured resource sets based on the sensing performance value for the configured resource sets.

[0180] At 814, the WTRU may send a sensing CSI report including, for example, sensing codebook entries, post-detection SNRs, sensing MMSDE, etc., per resource set. The WTRU may send a sensing CSI report including, for example, the subset of sensing PMIs per resource set (in wideband or per sub-band form), the post-detection SNRs, sensing MMSE values, etc.

[0181] At 816, the WTRU may determine if a stop condition is met. If the WTRU determines, at 816, that the stop condition has been met, the method 800 ends at 818.

[0182] Alternatively, if the WTRU determines, at 816, that the stop condition has not been met, the method 800 returns to 806, in which the WTRU may receive another set of RSs for sensing CSI acquisition and obtains channel responses at the resource sets. The WTRU may repeat the steps of the method 800 until a stopping condition is fulfilled, such as after aperiodic CSI reporting or when periodic or semi-periodic sensing CSI reporting is de-activated via (e.g., MAC CE or DCI).

[0183] Bistatic and multistatic sensing may be implemented. For example, methods and procedures to perform measurements by the WTRU on a second set of sensing RS received from a TRP, or a second WTRU, for bistatic and multistatic sensing.

[0184] The WTRU may be configured, indicated, or determined to measure and report one or more bistatic or multistatic sensing measurements.

[0185] The WTRU may obtain configuration information on bistatic or multistatic sensing comprising at least one of (i) a second set of sensing RS resources to perform bistatic or multistatic measurements transmitted in a periodic, aperiodic, or semi-persistent form, (ii) information about the sensing reports, (iii) ToA of the LOS component betweenthe TRP and the WTRII, and / or (iv) time interval to perform sensing measurements, specified as, for example, a start and end time or time duration (e.g., in a number of slots, absolute time units, etc.), or a pre-defined time interval.

[0186] The second set of sensing RS resources may be defined as one or more of (a) signals used to perform sensing measurements, including a positioning signal (e.g., DL PRS, UL SRS for positioning, etc.) and / or a dedicated sensing signal, (b) a start RE, a number of RBs, symbol and slot number, comb size and comb offset, if any, and / or (c) in the cases of periodic and semi-periodic RS for sensing, their periodicity in number of slots, frames, time duration, etc.

[0187] The information about the sensing reports may include an indication of whether sensing reports are aperiodic, periodic, or semi-persistent and the periodicity (e.g., in no. slots, time duration, etc.) in the two latter cases.

[0188] The information about the sensing reports may include sensing measurements per MPC up to an indicated or pre-configured maximum number of MPC. For example, the sensing reports may include AoA, ToA, RSRP, SNR, RTT, sensing MMSE, sensing MSE, etc.

[0189] The information about the sensing reports may include one or multiple thresholds for successful detection of the scatterers, including at least one of minimum RSRP, minimum SNR, maximum sensing MMSE, maximum sensing MSE, etc.

[0190] The information about the sensing reports may include an indication of whether the scatterer's location, its speed, or both should be reported for the scatterers detected by the WTRU.

[0191] The WTRU may receive a subset of active states for sensing that represent active beams aimed for bistatic / multistatic sensing by the WTRU (e.g., in the form of active TCI states for sensing). Active TCI states for sensing may comprise a subset of the available states for sensing configured for the WTRU (e.g., via an RRC IE, DCI signaling, MAC CE, etc.). The subset of active TCI states may be indicated to the WTRU through dynamic signaling (e.g., DCI, MAC CE, etc.).

[0192] FIG. 9 illustrates a system diagram 900 of an example of bistatic sensing measurements performed by a WTRU aided by sensing RS over one or multiple active TCI states for sensing. The WTRU may be a first WTRU that receives signals from aTRP or a second WTRU aimed for performing bistatic or multi-static sensing measurements. The WTRU may receive a second set of sensing RS corresponding to one or more active sensing states. The WTRU may perform one or more sensing measurements aided by the second set of sensing RS over the one or more active sensing states, including AoA, ToA, RSRP, RTT, sensing MMSE, sensing MSE, etc., per MPC, or for a subset of MPCs, up to a maximum number of MPCs. The WTRU may determine the location, speed, or both, of the identified scatterers based on the sensing measurements per configuration.

[0193] The WTRU may transmit a bistatic / multistatic sensing report over, for example, an uplink data or control channel (e.g., PUCCH, PUSCH, etc.). Sensing reports may include measurements and estimated values of the sensing quantities configured per each MPC, up to a maximum number of MPCs. The measurements and estimated values may include at least one of the measured sensing quantities per active state for sensing (e.g., active TCI state for sensing), including ToA, RTT, AoA, RSRP, SNR, etc. The measurements and estimated values may include sensing MSE, sensing MMSE, or both, per active state for sensing. The measurements and estimated values may include at least one of the locations, speed, or both, of the identified scatterers.

[0194] The measurements and estimated quantities may be reported per each MPC, or for a subset of MPCs, up to a maximum number of MPCs given by configuration or pre- defined by the implementation.

[0195] The WTRU may avoid reporting a sensing measurement performed on any multipath component with a high likelihood of being in LOS conditions (e.g., if its ToA matches the ToA of a LOS component received from the network as part of the configuration).

[0196] Based on a configuration, the WTRU may report the identified scatterers’ locations, the identified scatterers' speeds, and / or both, based on sensing measurements. The WTRU may report (e.g., only report) sensing measurements (e.g., AoA, ToA, sensing MMSE, etc.).

[0197] If the sensing accuracy does not meet a minimum pre-configured or implementation-defined threshold, then the WTRU may discard the correspondingmeasurement and include an indication in the report about, e.g., insufficient sensing accuracy.

[0198] The WTRU may repeat the above steps until a stopping condition is fulfilled, such as after aperiodic reporting and when periodic or semi-periodic sensing reports are de- activated via (e.g., MAC CE or DCI).

[0199] FIG. 10 is a flow chart diagram illustrating an example bistatic / multistatic sensing and reporting method 1000 by a WTRU. The method 1000 may be performed by any combination of a processor, memory, and transceiver of the WTRU. It should be appreciated that the example bistatic / multistatic sensing and reporting method 1000 may include one or more of the following.

[0200] At 1002, a WTRU may receive configuration information associated with sensing measurement and / or reporting, including a second set of RS, sensing report, ToA of LOS components, and / or time interval. The WTRU may be configured to measure and report bistatic or multistatic sensing measurements, including a second set of sensing RS resources for bistatic or multistatic measurements, defined by one of the type of signal, number of ports, resource sets, periodicity, etc., information about the sensing reports, e.g., its contents, periodicity, wideband / sub-band reporting mode, thresholds for scatterers’ detection, etc., ToA of the LOS component, and / or time interval to perform sensing measurements.

[0201] At 1004, the WTRU may receive a subset of active states for sensing (e.g., active TCI states for sensing) indicated via, for example, MAC CE or DCI.

[0202] At 1006, the WTRU may receive a second set of sensing RSs over one or more active sensing states and performs sensing measurements.

[0203] At 1008, the WTRU may send a bistatic or multistatic sensing report, including sensing quantities, and sensing MMSE per active sensing state. For example, the WTRU may send a bistatic / multistatic sensing report that includes any of the measured quantities, location and / or speed, per MPC or for a subset of MPCs, up to a maximum number of MPCs, sensing MSE, sensing MMSE, or both, and / or an indication of whether the sensing accuracy does, or does not, meet a pre-configured threshold

[0204] At 1010, the WTRU may determine if a stop condition is met. If the WTRU determines at 1010 that the stop condition has been met, the method 1000 ends in step1012. Alternatively, or additionally, if the WTRU determines at 1010 that the stop condition has not been met, then the method 1000 returns to step 1004, where the WTRU receives a subset of active states for sensing (e.g., active TCI states for sensing) indicated via, for example, MAC CE or DCI.

[0205] A WTRU may evaluate suitable metrics for sensing CSI information. The WTRU may propose criteria to determine optimal spatial directions for the best possible sensing accuracy. The WRU may implement procedures for the measurement and reporting of sensing CSI. The WTRU may implement bistatic and multistatic sensing procedures based on the sensing CSI information.

[0206] Spatial directions for sensing may be discretized in a codebook of precoding matrices for sensing. During a sensing CSI acquisition and reporting phase, codebook entries representing directions with the best possible sensing accuracy may be selected and reported by the WTRU, as part of the sensing PMI feedback, with the aid of a first RS for sensing CSI acquisition that may be transmitted in periodic, aperiodic, or semi- periodic mode. The reported sensing PMI values may refer to one or multiple sensing beams among a set of available TCI states configured for sensing. Sensing performance may be assessed by the WTRU for the different codebook entries based on certain performance criteria, e.g., a sensing MMSE, from which sensing PMI is reported in periodic, aperiodic, or semi-periodic mode until a stopping criterion is met.

[0207] During a sensing phase, the WTRU may be configured with a subset of active TCI states for sensing that may be dynamically activated via, for example, MAC CE or DCI. A second RS for sensing may be received by the WTRU for bistatic / multistatic measurements on the configured subset of active TCI states. Sensing reports may be transmitted by the WTRU in periodic, aperiodic, or semi-persistent mode, including sensing measurements, or location / speed information of the scatterers, until a stopping criterion is met.

Claims

CLAIMS:1 . A wireless transceiver / receiver unit (WTRU), comprising: a processor configured to: send a message to a network, the message indicating one or more channel state information (CSI) measurements supported by the WTRU; receive a plurality of reference signals (RSs), wherein the plurality of RSs is associated with a plurality of configured resource sets; determine, based on mutual information (Ml) associated with the plurality of RSs, a respective sensing performance value for each of the configured resource sets associated with the plurality of RSs; determine a respective set of precoding matrix indicators (PMIs) for each of the configured resource sets based on the respective sensing performance value for each of the configured resource sets; and send a sensing report indicating the respective set of PMIs and the respective sensing performance value for each respective configured resource set of the configured resource sets.

2. The WTRU of claim 1 , wherein the processor is further configured to: receive configuration information comprising spatial characteristics of the plurality of RSs.

3. The WTRU of claim 1 , wherein the set of PMIs are determined based on the sensing performance value for each respective configured resource set being within a predetermined range.

4. The WTRU of claim 1 , wherein the message comprises an indication of: 1 ) a supported performance metric for bistatic or multistatic sensing or 2) a sensing codebook supported by the WTRU.

5. The WTRU of claim 4, wherein the supported performance metric for bistatic or multistatic sensing comprises any of: Minimum Mean Square Error (MMSE), Signal toNoise Ratio (SNR), Reference Signal Received Power (RSRP), Root Mean Square (RMS) error of ranging estimation, RMS error of Angle of Arrival (AoA) estimation, RMS error of phase estimation, or RMS error of velocity estimation.

6. The WTRU of claim 1 , wherein the sensing performance value comprises a Minimum Mean Square Error (MMSE) value that is below a threshold.

7. The WTRU of claim 1 , wherein the sensing performance value comprises a Mean Square Error (MSE) value that is below a threshold.

8. The WTRU of claim 1 , wherein the Ml is a metric characterizing an amount of information carried by a channel associated with each of the configured resources sets.

9. The WTRU of claim 1 , wherein the sensing report comprises sensing codebook indexes per Channel State Information (CSI) RS Resource Indicator (CRI).

10. The WTRU of claim 1 , wherein the sensing performance value of a configured resource set indicates a statistical error associated with a sensing metric being measured for the configured resource sets.

11. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: sending a message to a network, the message indicating one or more channel state information (CSI) measurements supported by the WTRU; receiving a plurality of reference signals (RSs), wherein the plurality of RSs is associated with a plurality of configured resource sets; determining, based on mutual information (Ml) associated with the plurality of RSs, a respective sensing performance value for each of the configured resource sets associated with the plurality of RSs;determining a respective set of precoding matrix indicators (PMIs) for each of the configured resource sets based on the respective sensing performance value for each of the configured resource sets; and sending a sensing report indicating the respective set of PMIs and the respective sensing performance value for each respective configured resource set of the configured resource sets.

12. The method of claim 11 , further comprising: receiving configuration information comprising spatial characteristics of the plurality of RSs.

13. The method of claim 11 , wherein the set of PMIs are determined based on the sensing performance value for each respective configured resource set being within a predetermined range.

14. The method of claim 11 , wherein the message comprises an indication of: 1 ) a supported performance metric for bistatic or multistatic sensing or 2) a sensing codebook supported by the WTRU .

15. The method of claim 14, wherein the supported performance metric for bistatic or multistatic sensing comprises any of: Minimum Mean Square Error (MMSE), Signal to Noise Ratio (SNR), Reference Signal Received Power (RSRP), Root Mean Square (RMS) error of ranging estimation, RMS error of Angle of Arrival (AoA) estimation, RMS error of phase estimation, or RMS error of velocity estimation.

16. The method of claim 11 , wherein the sensing performance value comprises a Minimum Mean Square Error (MMSE) value that is below a threshold.

17. The method of claim 11 , wherein the sensing performance value comprises a Mean Square Error (MSE) value that is below a threshold.

18. The method of claim 11 , wherein the Ml is a metric characterizing an amount of information carried by a channel associated with each of the configured resources sets.

19. The method of claim 11 , wherein the sensing report comprises sensing codebook indexes per Channel State Information (CSI) RS Resource Indicator (CRI).

20. The method of claim 11 , wherein the sensing performance value of a configured resource set indicates a statistical error associated with a sensing metric being measured for the configured resource sets.

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