Methods, architectures, apparatuses, and systems for transmitting reference signals to transmission points

Abstract

Processes, methods, architectures, apparatus, systems, devices, and computer program products for transmitting reference signals to transmission points are described. A wireless transmit / receive unit (WTRU) receives information indicating a configuration for joint reception from a plurality of transmission points including a reference transmission point and for reporting a measurement of a relative error related to reference signals received from at least one pair of transmission points of the plurality of transmission points; transmits information indicating a measurement of a relative error related to reference signals received from the at least one pair of transmission points; transmits information indicating that the measurement of the relative error exceeds a given value upon determining that the measurement of the relative error exceeds the given value; receives information indicating a request for transmission of a calibration signal to at least one transmission point of the plurality of transmission points; and transmits the calibration signal in accordance with the request.

Description

[0001] Cross-references to related applications This application claims the benefit of U.S. Provisional Application No. 63 / 609,950, filed December 14, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0002] This disclosure generally relates to the fields of communications, software, and coding, including, for example, methods, architectures, apparatus, and systems for calibrating transmit / receive points using assistance from wireless transmit / receive units. Summary of the Invention

[0003] In a first aspect, this principle relates to a method at a wireless transmit / receive unit (WTRU), comprising: receiving information indicating a configuration for joint reception from a plurality of transmission points including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmitting information indicating the measurement relative error associated with the reference signal received from the at least one pair of transmission points; transmitting information indicating an excess of the measurement relative error when it is determined that the measurement relative error exceeds a given value; receiving information indicating a request to transmit a calibration signal to at least one of the plurality of transmission points; and transmitting the calibration signal according to the request.

[0004] In a second aspect, this principle relates to a wireless transmit / receive unit (WTRU) comprising at least one processor configured to receive information indicating a configuration for joint reception from a plurality of transmission points including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least a pair of the plurality of transmission points; transmitting information indicating an excess of the relative error when it is determined that the relative error exceeds a given value; receiving information indicating a request to transmit a calibration signal to at least one of the plurality of transmission points; and transmitting the calibration signal according to the request. Attached Figure Description

[0005] A more detailed understanding can be obtained by referring to the following detailed description, which is given by way of example in conjunction with the accompanying drawings. Like the detailed description, the figures in these drawings are illustrative. Therefore, the drawings (FIG.) and the detailed description should not be considered limiting, and other equally valid examples are possible and feasible. Furthermore, the same reference numerals (ref.) in the drawings denote the same elements, wherein: Figure 1A This is a system diagram showing an example communication system; Figure 1B It shows that it can be done Figure 1A The system diagram shown is of an example wireless transmit / receive unit (WTRU) used in the communication system. Figure 1C It shows that it can be done Figure 1A The system diagram shows an example radio access network (RAN) and an example core network (CN) used in the communication system shown. Figure 1D It shows that it can be done Figure 1A The system diagram shows another example RAN and another example CN used in the communication system shown; Figure 2 Receive and jointly demodulate PDSCH data coherently transmitted from two TRPs that are assumed to be synchronized in time and frequency; Figure 3 A flowchart of a method according to a first embodiment of this principle is shown; Figure 4 A flowchart of a method according to a second embodiment of this principle is shown; and Figure 5 The principle of special calibration of SRS transmission based on this principle is shown. Detailed Implementation

[0006] In the following detailed description, numerous specific details are set forth to provide a full understanding of the embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, processes, components, and circuits have not been described in detail so as not to obscure the description below. Furthermore, embodiments and examples not specifically described herein may be practiced in place of or in combination with the embodiments and other examples expressly, implicitly, and / or inherently described, disclosed, or provided herein (collectively, the “Provided”). Although various embodiments are described and / or claimed herein, in which apparatuses, systems, devices, etc., and / or any elements thereof perform operations, processes, algorithms, functions, etc., and / or any part thereof, it should be understood that any embodiment described and / or claimed herein assumes that any apparatus, system, device, etc., and / or any element thereof is configured to perform any operation, process, algorithm, function, etc., and / or any part thereof.

[0007] Example communication system.

[0008] The methods, apparatus, and systems provided herein are well-suited for communications involving both wired and wireless networks. (See also...) Figure 1A-1D An overview of various types of wireless devices and infrastructures is provided, in which various elements of the network can be utilized, performed, arranged and / or adapted and / or configured to the methods, apparatuses and systems provided herein.

[0009] Figure 1AThis is a system diagram illustrating an example communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multiple access system providing content such as voice, data, video, messaging, and broadcasting to multiple wireless users. The communication system 100 enables multiple wireless users to access this content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Zero-Tail (ZT) Unique Word (UW) Discrete Fourier Transform (DFT) Spread Spectrum OFDM (ZT UW DTS-s OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, Filter Bank Multicarrier (FBMC), etc.

[0010] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, radio access networks (RANs) 104 / 113, core networks (CNs) 106 / 115, public switched telephone networks (PSTNs) 108, the Internet 110, and other networks 112. However, it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. For example, WTRUs 102a, 102b, 102c, and 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include / or be user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain environments), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0011] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, and 102d, for example, to facilitate access to one or more communication networks (such as CN 106 / 115, Internet 110, and / or other networks 112). For example, base stations 114a and 114b may be base transceiver stations (BTS), node Bs (NBs), eNode-Bs (eNBs), home node Bs (HNBs), home eNode-Bs (HeNBs), gNode-Bs (gNBs), NR Node-Bs (NR NBs), site controllers, access points (APs), wireless routers, etc. Although base stations 114a and 114b are each depicted as a single element, it should be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0012] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of a specific geographic area, which may be relatively fixed or may change over time. The cell may also be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver per sector of the cell. In one embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each or any sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

[0013] Base stations 114a and 114b can communicate with one or more of WTRUs 102a, 102b, 102c, and 102d via air interface 116. Air interface 116 can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). Any suitable radio access technology (RAT) can be used to establish air interface 116.

[0014] More specifically, as described above, the communication system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base stations 114a and WTRUs 102a, 102b, and 102c in RAN 104 / 113 can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can establish an air interface 116 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 Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

[0015] In one embodiment, base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can use Long Term Evolution (LTE) and / or LTE-A Advanced (LTE-A) and / or LTE-A Pro Advanced (LTE-A Pro) to establish air interface 116.

[0016] In one embodiment, base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can establish an air interface 116 using a new radio (NR).

[0017] In one embodiment, base station 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can jointly implement LTE radio access and NR radio access, for example, using the dual connectivity (DC) principle. Therefore, the air interface utilized by WTRUs 102a, 102b, and 102c can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0018] In one embodiment, base station 114a and WTRUs 102a, 102b, and 102c can implement radio technologies such as IEEE 802.11 (i.e., Wi-Fi), IEEE 802.16 (i.e., WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), GSMEDGE (GERAN), etc.

[0019] For example, Figure 1A Base station 114b can be a wireless router, home node B, home eNode B, or access point, and can utilize any suitable RAT to facilitate wireless connectivity in a local area, such as commercial locations, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for drone use), roads, etc. In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d can utilize cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish any of small cells, picocells, or femtocells. Figure 1A As shown, base station 114b can have a direct connection to Internet 110. Therefore, it is not required for base station 114b to access Internet 110 via CN 106 / 115.

[0020] RAN 104 / 113 can communicate with CN 106 / 115, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRUs 102a, 102b, 102c, and 102d. Data can have different Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN106 / 115 can provide call control, billing services, location-based services, prepaid calling, internet connectivity, video distribution, and / or perform advanced security functions such as user authentication. Although in Figure 1A Although not shown, it should be understood that RAN 104 / 113 and / or CN 106 / 115 can communicate directly or indirectly with other RANs that use the same RAT as RAN 104 / 113 or a different RAT. For example, in addition to being connected to RAN 104 / 113, which may utilize NR radio technology, CN 106 / 115 can also communicate with another RAN (not shown) that uses any of the following radio technologies: GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or Wi-Fi.

[0021] CN 106 / 115 can also serve as a gateway for WTRU 102a, 102b, 102c, 102d to access PSTN 108, the Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP Internet Protocol suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 / 114 or a different RAT.

[0022] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 may include multi-mode capabilities (e.g., WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example... Figure 1AThe WTRU 102c shown can be configured to communicate with base station 114a, which can use cellular-based radio technology, and to communicate with base station 114b, which can use IEEE 802 radio technology.

[0023] Figure 1B This shows a system diagram of an example WTRU 102. (See diagram below.) Figure 1B As shown, among other things, 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 supply 134, a Global Positioning System (GPS) chipset 136, and / or other components / peripherals 138. It should be understood that WTRU 102 may include any sub-combination of the foregoing components while remaining consistent with the embodiments.

[0024] Processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. Processor 118 may perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable WTRU 102 to operate in a wireless environment. Processor 118 may be coupled to transceiver 120, and transceiver 120 may be coupled to transmitting / receiving element 122. Although Figure 1B The processor 118 and transceiver 120 are depicted as separate components, but it should be understood that the processor 118 and transceiver 120 can be integrated together, for example, in an electronic package or chip.

[0025] Transmitting / receiving element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, transmitting / receiving element 122 can be an antenna configured to transmit and / or receive RF signals. In one embodiment, transmitting / receiving element 122 can be, for example, a transmitter / detector configured to transmit and / or receive IR, UV, or visible light signals. In one embodiment, transmitting / receiving element 122 can be configured to transmit and / or receive both RF and optical signals. It should be understood that transmitting / receiving element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0026] Although the transmitting / receiving element 122 is in Figure 1BWhile depicted as a single element, WTRU 102 may include any number of transmitting / receiving elements 122. For example, WTRU 102 may employ MIMO technology. Thus, in one embodiment, WTRU 102 may include two or more transmitting / receiving elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via air interface 116.

[0027] Transceiver 120 can be configured to modulate signals transmitted by transmitting / receiving element 122 and demodulate signals received by transmitting / receiving element 122. As described above, WTRU 102 can have multi-mode capability. Therefore, for example, transceiver 120 may include multiple transceivers to enable WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11).

[0028] The processor 118 of WTRU 102 can be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light-emitting diode (OLED) display unit) and can receive user input data therefrom. The processor 118 can also output user data to the speaker / microphone 124, keypad 126, and / or display / touchpad 128. Furthermore, the processor 118 can access information and store data therein from any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. 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. Removable memory 132 may include a subscriber identity module (SIM) card, memory stick, secure digital storage (SD) card, etc. In other embodiments, the processor 118 can access information and store data therein from memory that is not physically located on WTRU 102 (such as on a server or home computer (not shown)).

[0029] The processor 118 may receive power from the power supply 134 and may be configured to distribute and / or control power to other components in the WTRU 102. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0030] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. In addition to, or instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via air interface 116, and / or determine its location based on the timing of signals received from two or more nearby base stations. It should be understood that the WTRU 102 may acquire location information using any suitable location determination method while remaining consistent with the embodiments.

[0031] Processor 118 may be further coupled to other components / peripherals 138, which may include one or more software and / or hardware modules / units providing additional features, functions, and / or wired or wireless connectivity. For example, component / peripheral 138 may include an accelerometer, electronic compass, satellite transceiver, digital camera (for photos and / or video), Universal Serial Bus (USB) port, vibration device, television transceiver, hands-free headset, Bluetooth® module, FM radio unit, digital music player, media player, video game player module, internet browser, virtual reality and / or augmented reality (VR / AR) device, activity tracker, etc. Component / peripheral 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, attitude sensor, biometric sensor, and / or humidity sensor.

[0032] WTRU 102 may include a full-duplex radio for which the transmission and reception of some or all signals (e.g., signals associated with specific subframes of both the uplink (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 to reduce and / or substantially eliminate self-interference through hardware (e.g., chokes) or through signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In one embodiment, WTRU 102 may include a half-duplex radio for which the transmission and reception of some or all signals (e.g., signals associated with specific subframes of either the uplink (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0033] Figure 1CThis is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 can communicate with WTRUs 102a, 102b, and 102c via air interface 116 using E-UTRA radio technology. RAN 104 can also communicate with CN 106.

[0034] RAN 104 may include eNode-B 160a, 160b, and 160c; however, it should be understood that RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiments. eNode-B 160a, 160b, and 160c may each include one or more transceivers for communicating with WTRU 102a, 102b, and 102c via air interface 116. In one embodiment, eNode-B 160a, 160b, and 160c may implement MIMO technology. Therefore, for example, eNode-B 160a may use multiple antennas to transmit and / or receive radio signals from WTRU 102a.

[0035] Each of the eNode-B 160a, 160b, and 160c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in the uplink (UL) and / or downlink (DL), etc. Figure 1C As shown, eNode-B 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0036] Figure 1C The CN 106 shown 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 is described as part of CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0037] The MME 162 can connect to each of the eNode-B 160a, 160b, and 160c in RAN104 via the S1 interface and can act as a control node. For example, the MME 162 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, bearer activation / deactivation, selecting a specific serving gateway during the initial attachment of WTRUs 102a, 102b, and 102c, etc. The MME 162 can provide control plane functions for handover between RAN104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0038] The SGW 164 can connect to each of the eNode Bs 160a, 160b, and 160c in RAN104 via the S1 interface. The SGW 164 can typically route and forward user data packets to / from WTRUs 102a, 102b, and 102c. The SGW 164 can perform other functions, such as anchoring the user plane during inter-eNode B handover, triggering paging when DL data is available for WTRUs 102a, 102b, and 102c, and managing and storing the context of WTRUs 102a, 102b, and 102c.

[0039] SGW 164 can connect to PGW 166, which can provide WTRU 102a, 102b, 102c with access to packet-switched networks such as Internet 110 to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices.

[0040] CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRU 102a, 102b, 102c with access to a circuit-switched network such as PSTN 108 to facilitate communication between WTRU 102a, 102b, 102c and traditional landline communication equipment. For example, CN 106 may include, or be able to communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN 106 and PSTN 108. Furthermore, CN 106 can provide WTRU 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0041] Despite WTRU in Figure 1A-1D While described as a wireless terminal, it is conceivable that in some representative embodiments, such a terminal may use (e.g., temporarily or permanently) a wired communication interface with a communication network.

[0042] In a representative embodiment, another network 112 may be a WLAN.

[0043] In Infrastructure Basic Services Set (BSS) mode, a WLAN may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distributed system (DS) or another type of wired / wireless network that transmits traffic to and / or out of the BSS. Traffic originating outside the BSS destined for a STA can be delivered to the AP. Traffic originating from a STA destined for a destination outside the BSS can be sent to the AP for delivery to the appropriate destination. For example, traffic between STAs within the BSS can be transmitted via the AP, where the source STA can send traffic to the AP, and the AP can deliver traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be transmitted between source and destination STAs (e.g., directly between them) using Direct Link Establishment (DLS). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using Standalone BSS (IBSS) mode may not have an access point (AP), and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode is sometimes referred to here as an "ad-hoc" communication mode.

[0044] When operating in 802.11ac infrastructure mode or a similar mode, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of a fixed width (e.g., a 20 MHz wide bandwidth) or dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example in an 802.11 system. For CSMA / CA, STAs including the AP (e.g., each STA) can sense the primary channel. If a particular STA senses / detects the primary channel and / or determines that the primary channel is busy, that particular STA can back off. A single STA (e.g., only one station) can transmit in a given BSS at any given time.

[0045] High-throughput (HT) STAs can communicate using a 40 MHz wide channel, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0046] Very High Throughput (VHT) STAs can support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. 40 MHz and / or 80 MHz channels can be formed by combining consecutive 20 MHz channels. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels, or by combining two non-consecutive 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, after channel coding, the data passes through a segment parser, which splits the data into two streams. Each stream can be processed separately using Inverse Fast Fourier Transform (IFFT) and time-domain processing. The streams can be mapped onto two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the operation of the 80+80 configuration can be reversed, and the combined data can be sent to the Media Access Control (MAC) layer, entities, etc.

[0047] 802.11af and 802.11ah support operating modes below 1 GHz. Compared to those used in 802.11n and 802.11ac, 802.11af and 802.11ah reduce channel operating bandwidth and carrier. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV Blank (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support metering-type control / machine-type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including supporting (e.g., only supporting) certain and / or limited bandwidths. MTC devices may include batteries with a battery life exceeding a threshold (e.g., to maintain a very long battery life).

[0048] WLAN systems that can support multiple channels and channel bandwidths (e.g., 802.11n, 802.11ac, 802.11af, and 802.11ah) include a channel that can be designated as the primary channel. The bandwidth of the primary channel can be equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STAs operating in the BSS, supporting minimum bandwidth operating modes. In the 802.11ah example, for STAs that support (e.g., only support) the 1 MHz mode (e.g., MTC type devices), the primary channel can be 1 MHz wide, 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 Sense 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 (supporting only the 1 MHz operating mode) transmitting to the AP, the entire available band can be considered busy, even if most of the band remains idle and may be available.

[0049] In the United States, the available frequency band for 802.11ah is from 902 MHz to 928 MHz. In South Korea, the available frequency band is from 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is from 916.5 MHz to 927.5 MHz. The total available bandwidth for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0050] Figure 1D This is a system diagram illustrating RAN 113 and CN 115 according to an embodiment. As described above, RAN 113 can communicate with WTRUs 102a, 102b, and 102c via air interface 116 using NR radio technology. RAN 113 can also communicate with CN 115.

[0051] RAN 113 may include gNBs 180a, 180b, and 180c; however, it should be understood that RAN 113 may include any number of gNBs while remaining consistent with the embodiments. gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from WTRUs 102a, 102b, and 102c. Therefore, for example, gNB 180a may use multiple antennas to transmit and / or receive radio signals from WTRU 102a. In one embodiment, gNBs 180a, 180b, and 180c can implement carrier aggregation technology. For example, gNB 180a can transmit multiple component carriers (not shown) to WTRU 102a. A subset of these component carriers can be on unlicensed spectrum, while the remaining component carriers can be on licensed spectrum. In one embodiment, gNBs 180a, 180b, and 180c can implement Coordinated Multipoint (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from gNBs 180a and 180b (and / or gNB 180c).

[0052] WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using transmissions associated with scalable digitization. For example, OFDM symbol spacing and / or OFDM subcarrier spacing can differ for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., including varying numbers of OFDM symbols and / or continuously varying absolute times).

[0053] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in standalone and / or non-standalone configurations. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNode-Bs 160a, 160b, and 160c). In standalone configuration, WTRUs 102a, 102b, and 102c can utilize one or more gNBs 180a, 180b, and 180c as mobility anchors. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in unlicensed frequency bands. In a non-standalone configuration, WTRUs 102a, 102b, and 102c can communicate / connect with gNBs 180a, 180b, and 180c, while also communicating / connecting with another RAN such as eNode-Bs 160a, 160b, and 160c. For example, WTRUs 102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNBs 180a, 180b, and 180c, as well as one or more eNode-Bs 160a, 160b, and 160c. In a non-standalone configuration, eNode-Bs 160a, 160b, and 160c can act as mobile anchors for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, and 102c.

[0054] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, network slicing support, dual connectivity, interoperability between NR and E-UTRA, routing user plane data to User Plane Functions (UPF) 184a and 184b, and routing control plane information to Access and Mobility Management Functions (AMF) 182a and 182b, etc. Figure 1D As shown, gNB 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0055] Figure 1DThe CN 115 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the foregoing elements is described as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0056] AMF 182a and 182b can connect to one or more gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can act as control nodes. For example, AMF 182a and 182b can be responsible for authenticating users of WTRU 102a, 102b, and 102c, supporting network slicing (e.g., handling different Protocol Data Unit (PDU) sessions with different requirements), selecting specific SMF 183a and 183b, managing registration areas, terminating NAS signaling, mobility management, and so on. AMF 182a and 182b can use network slicing, for example, to customize CN support for WTRU 102a, 102b, and 102c based on the type of service utilized by WTRU 102a, 102b, and 102c. For example, different network slices can 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, and services for MTC access. AMF 162 can provide control plane functions for handover between RAN 113 and other RANs (not shown) employing other radio technologies such as LTE, LTE-A, LTE-A Pro and / or non-3GPP access technologies such as Wi-Fi.

[0057] SMFs 183a and 183b can connect to AMFs 182a and 182b in CN 115 via the N11 interface. SMFs 183a and 183b can also connect to UPFs 184a and 184b in CN 115 via the N4 interface. SMFs 183a and 183b can select and control UPFs 184a and 184b, and configure the routing of services through UPFs 184a and 184b. SMFs 183a and 183b can perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0058] UPF 184a and 184b can be connected to one or more gNBs 180a, 180b, and 180c in RAN 113 via the N3 interface. This interface can provide WTRU 102a, 102b, and 102c with access to a packet-switched network (e.g., Internet 110), for example, to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices. UPF 184 and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-destination PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0059] CN 115 can facilitate communication with other networks. For example, CN 115 may include, or be able to communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN 115 and PSTN 108. Furthermore, CN 115 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRUs 102a, 102b, and 102c can be connected to local data networks (DNs) 185a and 185b via UPFs 184a and 184b through their N3 interfaces and the N6 interface between UPFs 184a and 184b and DNs 185a and 185b.

[0060] Given Figure 1A-1D as well as Figure 1A-1D The corresponding descriptions herein regarding any one or more of the functions described for WTRU 102a-d, base station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF183a-b, DN 185a-b, and / or any other element / device described herein may be performed by one or more emulated elements / devices (not shown). An emulation device may be one or more devices configured to emulate the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0061] Simulation devices can be designed to perform one or more tests on other devices in laboratory and / or carrier network environments. For example, one or more simulation devices can perform one or more or all of their functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more simulation devices can perform one or more or all of their functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. For testing purposes, simulation devices can be directly coupled to another device and / or can use over-the-air wireless communication to perform tests.

[0062] One or more simulation devices can perform one or more functions, including all functions, without being implemented / deployed as part of a wired and / or wireless communication network. For example, simulation devices can be used to test test scenarios in laboratory and / or non-deployed (e.g., testing) wired and / or wireless communication networks to implement testing of one or more components. One or more simulation devices can be test devices. Simulation devices can transmit and / or receive data using direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas).

[0063] introduce.

[0064] Currently, the UE supports multi-transmit / receive point (TRP) reception in either single downlink control information (sDCI) or multi-DCI (mDCI) modes. In sDCI mode, simultaneous reception from two non-collocated TRPs is supported in coherent joint transmission (CJT) scenarios. Both configurations completely overlap in the frequency domain, using the same channel and channel bandwidth. In the 3GPP 5G Rel-18 discussion, the maximum number of TRPs configured in CJT is four. The UE can report channel state information (CSI) feedback using a bitmap model, based on the gNB configuration mode, or based on UE-selective CSI reporting. The UE receives data from both TRPs on the physical data shared channel (PDSCH) and performs joint reception and demodulation, assuming the TRPs are synchronized in frequency and time within the cyclic prefix (CP). These multi-TRP coherent transmissions are expected to increase the signal-to-noise ratio (SNR), thereby improving the block error rate (BLER) of the received PDSCH data. Synchronization with the network always relies on the anchor TRP (anchor serving cell), while other TRP reference signals (RS) (TRS - tracking RS) are monitored and measured for CSI feedback and beamforming purposes.

[0065] Figure 2The illustration shows a UE receiving and jointly demodulating PDSCH data coherently transmitted from two TRPs that are assumed to be synchronized in time and frequency. UE 210 receives a first DL beam 220 from TRP 1 and a second DL beam 230 from TRP 2.

[0066] The base station's current frequency accuracy is + / - 0.05 ppm, while the UE should be within + / - 0.1 ppm. Furthermore, timing accuracy is within CP, as the UE will always measure the primary synchronization signal (PSS) and secondary synchronization signal (SSS) and obtain the first significant path as a reference. While this is good enough for single TRP / cell reception, assuming all channels are synchronized with the PSS / SSS at the TRP level, when CJT is configured, two TRPs transmit, and significant degradation in data reception has been observed for joint demodulation when frequency and timing synchronization discrepancies occur (up to 25% BLER when combined frequency and time are involved).

[0067] In this context, it has been observed that the maximum tractable delay spread decreases as the precoding matrix indicator (PMI) subband increases. Furthermore, a slight frequency drift within 0.05 ppm at the base station over 5 ms can cause phase shift, potentially creating cancellation points / regions within the equalized received signal, leading to demodulation errors.

[0068] Because CJT scenarios have more stringent time and frequency accuracy requirements than other deployment types, UE assistance is needed to help the TRP calibrate its transmission in time and frequency to achieve its goals. UE assistance can be implemented as feedback measurements or triggered measurements for TRP calibration.

[0069] As mentioned above, CJT-related CSI feedback supports up to four configured TRP candidate CSI reports. There are two supported CSI reporting modes: one configured by the gNB, and the other where the UE uses a bitmap model to report the CSI configured for CJT.

[0070] However, there is no information related to the relative frequency or timing drift value, which would have been helpful in the TRP calibration process to support CJT configuration.

[0071] In the CJT configuration, there is no UE reporting / feedback information for time and frequency drift. This information is necessary for TRP calibration to support CJT performance. The methods described herein cover UE-assisted reporting, TRP calibration, and UE behavior during the process.

[0072] Relative timing and frequency error measurement reports and TRP calibration process.

[0073] During mTRP CJT operation, the UE performs CSI measurement / reporting for the configured TRPs. As supplementary information, the UE measures and reports the relative time / frequency errors between the configured TRPs to support the calibration process. After the gNB receives the supplementary information, a time gap is required to calibrate the TRPs with errors; during this period, mTRP CJT operation cannot be supported for the TRPs under calibration.

[0074] However, calibration time slots are not currently supported. When the UE is operating under mTRP CJT, there is no defined UE behavior after error reporting and / or during time slots configured or indicated by the gNB (e.g., for calibration).

[0075] In a first embodiment, the UE receives configuration information for CJT operation (up to 4 TRPs) and has a new triggered CSI measurement report based on the configured TRS resources for the relative time and frequency errors between the first and second TRPs, the first and third TRPs, etc., or between any indicated TRP pairs. Measurements can be periodic or triggered, aperiodic / semi-persistent. One of the TRPs can be configured / indicated as a reference / anchor / default / master TRP for measurements of a reference signal (e.g., CSI-RS).

[0076] When non-periodic / semi-persistent, the UE is triggered, for example via MAC-CE or DCI command (order), via semi-static CSI-RS configuration, and for measurements used for timing and frequency error reporting.

[0077] When periodic, UE behavior (e.g., reporting) can be triggered by a combination of the following conditions: relative timing error exceeds a configured value, frequency error exceeds a configured value, and PDSCH BLER error exceeds a configured value.

[0078] The UE reports the relative error between TRPs (e.g., between each TRP and the default / anchor / master TRP or between TRP pairs).

[0079] The UE receives scheduled DL gaps, which can be a single scheduling gap or a series of gaps, to initiate TRP calibration (frequency and / or timing) (e.g., involving changes to gNB phase-locked loop (PLL) tracking or DL ​​timing adjustments), which may render the CJT inoperable.

[0080] After reporting the relative error and during the DL scheduling interval, the UE can perform different actions.

[0081] During multiple scheduling gaps of (multiple) specific TRPs, the UE can fall back from CJT (received based on two TRPs) operation to the default operation mode. The default operation mode can be a single TRP operation with a default / master / anchor configured TRP between error reporting and the end of the calibration gap, or an mTRP CJT operation with a subset of configured TRPs that meet one or more conditions (e.g., time / frequency error within a certain range, meeting BLER performance, e.g., 10%).

[0082] During the default operating mode, the UE can perform various measurement or monitoring actions.

[0083] The UE can perform CSI measurements / reports on the default TRP or a subset of configured TRPs that meet the conditions. After reporting the relative error, the UE can receive a MAC-CE indicating the Channel Measurement Resource (CMR) limitations of the CSI feedback, which are limited to a subset of the CMR index (by activating / deactivating CMRs from the CSI report, discarding deactivated CMR indexes, or using a bitmap that excludes limited CMRs).

[0084] The UE can monitor a subset of the PDCCH search space associated with the default TRP or a subset of the configured TRPs that meet the conditions.

[0085] The UE can measure a subset of reference signals associated with a subset of the default / master / anchor TRP or a subset of the configured TRPs that meet the conditions (e.g., for radio link monitoring / radio resource management (RLM / RRM)).

[0086] After the time interval of gNB configuration or indication, the UE may perform at least one of the following: CSI measurement / reporting for all configured TRPs, monitoring of all PDCCH search spaces associated with all configured TRPs, and measurement of reference signals for RLM / RRM associated with all configured TRPs.

[0087] TRP calibration process based on trigger probe reference signal (SRS).

[0088] During mTRP CJT operation, the UE can measure and report the relative time / frequency error between the configured TRPs to support the calibration process.

[0089] However, a relative time / frequency error has not yet been defined for the mTRP report format. Explicit reporting of relative time / frequency error values ​​requires excessive feedback overhead.

[0090] The UE is configured for CJT operation and is configured to perform TRP frequency / timing relative measurements using the RS configured per TRP. The TRP is indicated / configured as a reference / anchor TRP. The UE is configured with a set of Sound Reference Signal (SRS) resources, where each SRS resource is associated with an SRS Resource Indicator (SRI), and each SRI is associated with a TRP index.

[0091] The UE performs frequency / timing error measurement on each TRP pair, which includes a first TRP and a second TRP, wherein (e.g., for each pair) the first TRP can be an anchor / reference TRP.

[0092] When the difference exceeds a configured threshold, the UE can flag / indicate the excessive relative frequency / timing error between the first and second measured TRPs. The UE can also indicate the TRP index of the second TRP.

[0093] Following the transmit frequency / timing error indication, the UE may receive a "Special Calibration SRS" transmission request. The SRS request DCI may include an "SRS calibration indication flag," an SRI corresponding to the second TRP, an SRI corresponding to the SRS resource associated with the second TRP, a Transmission Configuration Indicator (TCI) state associated with the first TRP (e.g., reference / anchor TRP), and at least one of a set of N SRIs corresponding to the respective N SRS resources associated with the corresponding TRP. The TCI state informs the UE how to associate RS and SSB according to the quasi-configuration (QCL) of the transmit signal, and how the UE (beam, etc.) will use or apply spatial filters.

[0094] In response to receiving a special SRS request, the UE may transmit a first SRS in the resources associated with the first TRP (e.g., the reference TRP) using the frequency and timing associated with the first TRP (e.g., the reference TRP).

[0095] In response to receiving a special SRS request, the UE may use the indicated SRS resources to transmit a second SRS and adjust the transmission time and / or frequency based on the measurement time and / or frequency error determined for the second TRP relative to the first TRP.

[0096] If a set of N SRIs is indicated to the UE in the SRS calibration request, the UE may transmit SRS in each of the SRS resources corresponding to the N SRIs, wherein the time and / or frequency of each SRS transmission is adjusted based on the measurement time and / or frequency error of the corresponding TRP relative to the reference / first TRP.

[0097] SRS transmissions or N SRS transmissions can be based on the indicated TCI state (e.g., a spatial filter based on the indicated TCI state can be used).

[0098] TRS-based measurement reports and calibration gap UE behavior Figure 3 A method according to a first embodiment of this principle is shown.

[0099] In step S310, the UE receives configuration information for CJT operation (up to 4 TRPs) and has a new triggered CSI measurement report based on the configured TRS resources for the relative time and frequency errors between the first and second TRPs, the first and third TRPs, etc., or between any indicated TRP pairs. The measurement can be periodic or triggered aperiodic / semi-persistent. One of the TRPs can be configured / indicated as the anchor / default / master TRP for the measurement reference signal (e.g., CSI-RS).

[0100] When non-periodic / semi-persistent, the UE is triggered, for example, by MAC-CE or DCI commands, by semi-static CSI-RS configuration, and by measurements for timing and frequency error reporting.

[0101] When periodic, UE behavior (e.g., reporting) can be triggered by a combination of the following conditions: relative timing error exceeds a configured value, frequency error exceeds a configured value, and PDSCH BLER error exceeds a configured value.

[0102] In step S320, the UE reports the relative error between TRPs (e.g., between each TRP and the default / anchor / master TRP or between TRP pairs).

[0103] In step S330, the UE receives information indicating a scheduled DL gap, which can be a single scheduled gap or a series of gaps to initiate TRP calibration (frequency and / or timing) (e.g., involving changes in gNB PLL tracking or DL ​​timing adjustment), which may render CJT operation inoperable.

[0104] In step S340, after reporting the relative error and upon receiving information indicating the DL scheduling gap, the UE can perform different actions.

[0105] During multiple scheduling gaps of (multiple) specific TRPs, the UE can fall back from CJT (received based on two TRPs) operation to the default operation mode. The default operation mode can be a single TRP operation with a default / master / anchor configured TRP between error reporting and the end of the calibration gap, or an mTRP CJT operation with a subset of configured TRPs that meet one or more conditions (e.g., time / frequency error within a certain range, meeting BLER performance, e.g., 10%).

[0106] During the default operating mode, the UE can perform various measurement or monitoring actions.

[0107] The UE can perform CSI measurements / reports on a subset of the default TRP or configured TRP that meets the conditions. After reporting the relative error, the UE can receive a MAC-CE indicating the CMR limitation for the CSI feedback limited to a subset of the CMR index (by activating / deactivating the CMR from the CSI report, discarding the deactivated CMR index, or using a bitmap that excludes the limited CMR).

[0108] The UE can monitor a subset of the PDCCH search space associated with the default TRP or a subset of the configured TRPs that meet the conditions.

[0109] The UE can measure a subset of reference signals associated with the default / master / anchor TRP or a subset of configuration TRPs that meet the conditions (e.g., for RLM / RRM).

[0110] In step S350, after the time interval of gNB configuration or indication, the UE may perform at least one of the following: CSI measurement / reporting for all configured TRPs, monitoring the PDCCH search space associated with all configured TRPs, and measuring the reference signal of RLM / RRM associated with all configured TRPs.

[0111] In CJT mode operation, the UE is configured to jointly receive PDSCH from N TRPs, which are comprised of... Instructions. In the UE configuration, the number of TRPs can be limited, for example, N <= 4. From this group of configured TRPs, one TRP can be configured as the UE's default / primary / anchor TRP. A TRS can be configured for each TRP for the UE. This TRS can be configured to work with the set. x Each TRP or subset of TRPs (e.g., first and second TRPs, where the first TRP is the anchor TRP, first and third TRPs, etc.) is associated with a non-periodic / semi-persistent or periodicity.

[0112] The TRS configured for each TRP can be dedicated to synchronization measurements, or the UE can use the configured CSI-RS or SSB to derive CJT-related synchronization measurements. Alternatively, the UE can use the demodulation reference signal (DM-RS) embedded in the PDSCH.

[0113] When TRS is configured for CJT synchronization, CSI-RS configurations can be assigned to the same symbols with a granularity that each appears at least once in the time domain for each measurement / reporting time interval (e.g., for each 5 ms reporting interval). In the frequency domain, CSI-RS may or may not overlap.

[0114] When TRS is configured for non-periodic / semi-persistent measurements in semi-static mode, the network can use the DCI or MAC-CE activation command. In this case, TRS activation can be activated for a specific pair or more TRPs (a pair of TRPs can be, for example, a first default / master / anchor TRP and a second TRP). Alternatively, all TRSs for all TRPs can be activated for a complete set of CJT measurement reports.

[0115] First, the UE calculates the time and frequency errors based on the default / primary / anchor TRP. Then, the UE calculates based on... x The remaining TRP in the set is used to calculate the relative frequency and time error relative to the default / master / anchor TRP. For proper operation in CJT mode, the UE requires fine synchronization, which means that in the set... x At least two TRPs in the range are below a defined threshold.

[0116] Multiple frequency and / or timing error thresholds can be specified and / or configured by the network. Additionally or alternatively, the UE can be configured with CJT-related BLER thresholds / triggers for measurement reporting.

[0117] In one embodiment, synchronization is relative to the default / master / anchor TRP. The TRS for each TRP, along with the defined triggers, can be configured by the network in accordance with CJT configuration or as part of CJT configuration.

[0118] In this embodiment, the UE can periodically measure / evaluate CJT synchronization and report a subset of the configured TRP out-of-sync thresholds based on one or more triggers.

[0119] UE can be configured with time. and frequency The synchronization error threshold is set above, and can be used for relative time and frequency errors relative to the default / master / anchor TRP that exceed any or and The TRP or TRP pair of both triggers a report.

[0120] Alternatively, the UE can trigger a synchronization error report when a specified / configured BLER threshold is exceeded. The BLER threshold can be a separate trigger for CJT synchronization error reporting. The BLER threshold can only be activated when the last two TRPs or all TRPs in set x exceed time and / or frequency CJT-related thresholds.

[0121] The UE can be configured with an RSRP threshold. and or and Both, and the error in identifying their time and frequency is less than or and Both and their RSRP is higher than The TRP triggers a synchronization error report.

[0122] The UE can identify when its RSRP is higher than When a TRP is detected, a synchronization error report is triggered, and the identified TRP and its corresponding time / frequency error or both time and frequency error are reported.

[0123] UE can omit the set x It identifies the TRPs or TRP pairs that are in sync and reports the remaining TRPs or TRP pairs that are in error.

[0124] In one embodiment, the UE can be based on a configured (or indicated) set x (e.g., The first TRP is determined as the anchor (e.g., primary, main, default) TRP, while the second TRP is determined by, for example, an aperiodic / semi-persistent trigger emitted from the gNB (e.g., via DCI).

[0125] In one example, the UE may determine the first TRP as the TRP of the serving cell, for example, where the UE monitors the PDCCH received from the TRP via CORESET. The UE may determine the first TRP as the TRP associated with a CORESETpoolID value. The CORESETpoolID value may be fixed to the lowest ID (e.g., CORESETpoolID = 0). The CORESETpoolID value may be configured or indicated for determining the first TRP; for example, CORESETpoolID may be 0 or 1, or another value, which may provide operational flexibility to the UE depending on the network implementation, allowing the TRP to be set to any TRP within set x.

[0126] Based on determining the first TRP (e.g., a TRP within set x), the UE can determine a set y that includes N-1 (or fewer than N-1) TRPs within set x, excluding the first TRP. For example, if the first TRP is determined to be trp1, then the UE can determine set y as... If the first TRP is determined to be trpN, then the UE can determine the set y as... .

[0127] The UE may receive (e.g., from a gNB) an indication that triggers a non-periodic / semi-persistent measurement (and / or reporting) of time and frequency errors of a pair of TRPs. This indication may be received via a DCI (and / or via MAC-CE). The DCI may be a UL-granted or group-public DCI. The UE may be (configured to) determine at least one field in the indication (e.g., the DCI) indicating one or more TRPs within the set y.

[0128] The UE can identify the first pair of TRPs as the first TRP and the second TRP included in the set y. Based on receiving this indication (e.g., DCI), the UE can identify the second TRP from the set y. Based on identifying the second TRP, the UE can perform a first aperiodic / semi-persistent measurement (and / or report) on the time and frequency error of the first pair of TRPs (between the first and second TRPs).

[0129] The UE can identify the second pair of TRPs as the first and third TRPs included in the set y. Based on receiving this indication (e.g., DCI), the UE can determine the third TRP from the set y. Based on determining the third TRP, the UE can perform a second aperiodic / semi-persistent measurement (and / or report) on the time and frequency error of the second pair of TRPs (between the first and third TRPs).

[0130] In one example, the UE may be configured to report first and second aperiodic / semi-persistent measurements based on this indication (e.g., DCI). In another example, the UE may be configured to report selective aperiodic / semi-persistent measurements (among multiple aperiodic / semi-persistent measurements, e.g., first and second aperiodic / semi-persistent measurements). The UE may determine selective aperiodic / semi-persistent measurements based on a configured or pre-configured (or defined) function. This configuration or function may instruct the determination of selective aperiodic / semi-persistent measurements based on a pair of TRPs, representing the maximum (or greater than a threshold) time and frequency error between TRPs associated with that pair of TRPs. In another example, the configuration or function may instruct the determination of selective aperiodic / semi-persistent measurements based on a pair of TRPs, representing the minimum (or less than a threshold) time and frequency error between TRPs associated with that pair of TRPs.

[0131] When the BLER related to UE PDSCH CJT operation is detected to exceed a certain threshold, the network can trigger aperiodic / semi-persistent TRP synchronization measurement and reporting.

[0132] Alternatively, the UE can transmit a CJT synchronization error indication. This indication format can be configured as a single-bit indication, or it can be a complete bitmap of N TRPs, configured TRP pairs, or a bitmap relative to the default / master / anchor configured TRPs. The synchronization error indication can be transmitted, for example, using PUCCH, PUSCH UCI, or MAC CE. Alternatively, it can be a Radio Resource Control (RRC) triggered error indication.

[0133] Since synchronization error measurement is performed at the physical layer, the triggering of this indication can be based on a defined number of consecutive errors detected. The asynchronous state can have a network-configured / defined counter, Nout. This counter can be reset by detecting a synchronization instance of a pair of TRPs. The counter can be configurable, or the UE can follow a simple specified value to trigger the synchronization error indication.

[0134] When a synchronization error indication is triggered, the UE may receive an aperiodic / semi-persistent synchronization measurement command via MAC-CE or DCI. This command may include at least one of the following: a target pair or TRP for measurement, a TRP relative to the default / master / anchor TRP, a subset of TRP pairs, slot offset activation of the TRS configured by RRC, a single measurement, a specific measurement duration (e.g., in terms of the number of slots), and the start of a measurement with a stop command from the network (e.g., MAC CE semi-static measurement deactivation).

[0135] After executing the CJT-related aperiodic / semi-persistent measurement command, the UE can send a measurement report. The measurement report can be customized and may include the required information (e.g., a measurement instance for each TRP pair, which may include incremental (delta) frequency error and / or timing error), with a defined granularity of time and / or frequency as requested / configured by the network. Quantized measurement reports can be sent via PUCCH, PUSCH UCI, or MAC-CE. Alternatively, a Layer 3 RRC measurement report can be sent along with all the aforementioned information.

[0136] Upon receiving timing and / or frequency error reports (auxiliary information) related to the UE, the gNB can decide to perform calibrations, such as frequency and timing adjustments. Since changes in frequency and timing require a phase-locked loop (PLL) for frequency fine-tuning and timing adjustments, i.e., a pause in the RF front end, the gNB can schedule DL calibration intervals.

[0137] The gNB determines the scheduling of DL calibration gaps based on the required level of time / frequency calibration. The gNB also needs to consider priorities and potential conflicts with other activities, such as Hybrid Automatic Repeat Request (HARQ) processes or scheduled UL transmissions.

[0138] DL calibration gaps can be single gaps or gap bursts. Gap bursts can be scheduled to accommodate larger timing changes. In one embodiment, the gNB schedules a series of gaps, where smaller timing changes are performed sequentially to accommodate the autonomous timing adjustment steps and rates of UEs connected to a TRP involving CJT.

[0139] The UE can receive DL calibration gaps via DCI, which provides the gNB with the opportunity to adapt the DL calibration gap settings based on real-time network conditions and UE feedback. DCI indications may include a single gap or gap burst, start and duration, or multiple start slots and durations, as well as one or more of the expected UE behavior, which will now be described in more detail.

[0140] Single gap or gap burst: In one embodiment, semi-persistent scheduling can be indicated for DL ​​calibration gaps that recur at regular intervals, which can reduce signaling overhead and eliminate the need for the UE to continuously monitor the control channel.

[0141] The start and duration (in timeslots) of the DL calibration gap, based on the DL time slot or only the DL portion of the time slot. In one embodiment, an indication of the DL calibration gap can be received in time slot "n" for TRP calibration at time slot offset "n+G".

[0142] In the case of gap bursts, multiple start slots and durations can be indicated to outline each gap in the burst sequence. In one embodiment, the periodicity of the gaps within the gap burst is indicated.

[0143] Expected UE behavior during DL calibration gap: In one embodiment, DCI includes information such as resource blocks that will not be used by the UE for UL transmission during the DL calibration gap.

[0144] Alternatively, the UE can receive the DL calibration gap setting via higher-layer signaling such as RRC or MAC-CE. This is less flexible than dynamic scheduling, but can be used when calibration requirements are predictable and consistent.

[0145] In another embodiment, the gNB can use a predefined pattern (known to both the gNB and the UE) for the DL calibration gap, which is aligned with other periodic events in the network (e.g., SSB transmissions).

[0146] During the DL calibration gap time window, the TRP undergoing calibration does not support the mTRP CJT operating mode. The UE can interpret its behavior during the DL calibration gap as one or more actions in the following ways.

[0147] The UE can choose not to monitor the PDCCH (e.g., the UE does not seek scheduling decisions or HARQs during the time window).

[0148] The UE may opt out of performing any UL transmissions (e.g., PUCCH, PUSCH, PRACH, SRS, etc.).

[0149] The UE can use the calibration gap to adjust its TA value.

[0150] The UE can block PDSCHs expected to come from a specific TRP or TRP group that is determined to be uncalibrated (e.g., outside the mTRP CJT functional range).

[0151] The UE can reset frequency and timing-related measurements as well as (multiple) related timers.

[0152] The UE can de-prioritize, not accumulate, or measure any RS from a specific TRP or TRP group determined to be uncalibrated. In one embodiment, the CJT's configured CSI reporting priority can be set to a minimum value. For example, if the CJT is part of a CC that is part of a CA configuration, the CJT's frequency / time measurement priority becomes zero during the DL calibration time window. In one embodiment, CJT CSI reporting can be completely suspended until the UE receives the correct synchronization RS. This CSI reporting suspension can be determined by the report trigger time and the end of the configured calibration gap, plus at least the duration until the first calibration RS is received.

[0153] Furthermore, the gNB can activate / deactivate CSI feedback restrictions on a subset of the CMR index sent from the CSI report. This CSI feedback configuration, which will be received by the UE to restrict its CSI measurement to a subset of the CMR index, can be signaled via MAC-CE. In this case, UE behavior may include at least one of the following actions.

[0154] The UE discards the CSI of the deactivated CMR index. In one embodiment, the number of CSI-RS resources selected is .

[0155] The UE considers a restricted bitmap where it does not measure the CSI of the deactivated CMR index. In one embodiment, the UE is expected to select a CSI-RS resource, where... .use Bitmap To report UE selection, where CSI-RS resources are selected based on their order in the resource set. arrive The mapping is performed, and the first CSI-RS resource among the N selected CSI-RS resources corresponds to the non-zero bit with the lowest index.

[0156] As the DL calibration gap nears its end, the UE prepares to resume normal operation, such as re-enabling UL transmission and monitoring PDCCH.

[0157] After the relative frequency / time error and calibration gap have been reported, the UE may behave in different ways, as will be described now.

[0158] The UE can determine that the network performs calibration of one or more TRPs during the DL scheduling gap. The UE can determine, based on the correlation between the DL scheduling gap and the TRPs, that the DL scheduling gap applies to one or more TRPs from a set of TRPs configured for CJT. During the DL scheduling gap, one or more TRPs may be unable to participate in CJT operating mode.

[0159] In one embodiment, after reporting a relative error and upon receiving a DL scheduling gap, the UE can fall back from CJT mode to a default operating mode. The default operating mode may include one or more TRPs from a set of TRPs configured for CJT. Alternatively, the default TRP may be outside the CJT set. The UE can operate in fallback mode for a duration given by the length of the DL scheduling gap or by a timer configured with the DL scheduling gap. The UE determines the default / primary / anchor TRP and one or more TRPs based on constraints on CSI-RS measurement resources (CMR). The UE may restrict the CMR index to a subset of the index based on one or more of the following methods.

[0160] UEs can be pre-configured using indices that form a default set of restricted TRPs (e.g., minimum CMR, UTCI state, coresetPoolIndex, RS).

[0161] The UE can receive a MAC-CE after reporting a relative synchronization error. The MAC-CE may include an index of a potentially restricted CMR or CMR pair. The MAC-CE may include a bitmap to indicate active / inactive / discarded CMR indices.

[0162] The UE can be configured to count the number of times a measurement condition is met, and can initiate a limit after the count exceeds the configured number. One or more of the following can be considered as measurement conditions for at least one resource in the CMR: the signal quality (e.g., Reference Signal Received Power (RSRP), Signal-to-Interference Plus Noise (SINR), Signal-to-Noise Ratio (SNR)) is higher than the configured threshold for at least one resource in the CMR, and the time / frequency synchronization error of each TRP or the relative error between TRPs is higher than the configured threshold.

[0163] The default operating mode can be a UE fallback to a single TRP operating mode, where the single TRP is the default / primary / anchor TRP. The UE can report CSI based solely on the assumptions of a single TRP. For example, the UE can be configured with CSI reporting for multiple TRPs (CJT or NCJT), where it can be expected that the UE reports CSI for both single and multiple TRPs. The UE can prioritize reporting CSI for a single TRP and can discard content based on assumptions for multiple TRPs. The UE can consider received QCL assumptions or spatial filters configured for a single TRP. For example, the UE can receive a PDSCH with a ULTCI configured with two states. During the DL scheduling gap, the UE can determine that the first TCI state is active and the second TCI state is deactivated. The UE can restore the activation of both TCI states at the end of the DL scheduling gap.

[0164] The UE can also (alternatively or additionally) fall back to an operating mode that considers a subset of TRPs. The UE can receive the association between DL scheduling gaps and TRP indices. The UE can determine that TRPs not associated with DL scheduling gaps are active, and TRPs associated with DL scheduling gaps are inactive. The UE can prioritize CSI reports for a subset of TRPs in the restricted set.

[0165] In order to initiate restrictions, the UE can determine that only restricted CMR indices remain active, and can expect to perform RS measurements or monitoring only on active CMR indices.

[0166] For example, a UE can be configured with CMR1 and CMR2. The UE determines the limitation that CMR1 remains active while CMR2 is deactivated. The UE can consider the CSI reporting configuration based on measurements from CMR1, and can only consider measurements based on CMR2 after determining that CMR2 will be reactivated (e.g., determined by the UE, activated either by a network command or based on a timer configured for the duration of the DL scheduling interval).

[0167] As another example, it can be expected that the UE performs monitoring / measurement of RS only on the active CMR index, and that the UE resumes monitoring / measurement of RS on the inactive CMR index at the end of the DL scheduling gap. DL RS can be configured for purposes such as RRM / RLM, beam management, CSI reporting, etc. It can also be expected that the UE transmits UL RS only to the active TRP and resumes transmission to the inactive TRP at the end of the DL scheduling gap.

[0168] In one embodiment, it may be expected that the UE monitors a subset of the PDDCH search space based on the active CMR / TRP during the DL measurement gap, and resumes monitoring of all CMR / TRPs at the end of the DL scheduling gap.

[0169] After the UE reports a relative error and / or during a DL scheduling gap, the UE can fall back to the default mode from a receive mode based on joint transmission (e.g., from CJT or NCJT). The default operating mode can be receive from a single TRP or from a pair of TRPs. During the default operating mode, the UE can perform one or more of the following: One or more CMR or TRP indices in the default operating mode used for CSI measurements can be dynamically configured / indicated (e.g., via DCI and / or MAC-CE). Alternatively, the UE can dynamically determine one or more TRP indices for operation in the default mode and report them to the gNB in ​​the CSI report.

[0170] When a UE is configured with a codebook-based CJT operating mode, for example, txconfig ='type-II-CJT-r18' or txconfig ='type II-CJT-PortSelection-r18', the UE in the default operating mode can perform one or more of the following: codebook subset restriction (CBSR) and management of uplink resources for UCI reporting.

[0171] Codebook Subset Restriction (CBSR): In Rel-18 CJT, up to four TRPs can be configured for a CJT operation. A CBSR in Rel-18 CJT is configured for at least one TRP, while the CBSR configuration for the remaining TRPs is optional. When a CBSR is configured for a TRP and the index of that TRP is not included in the set of TRPs(multiple) operating in the default operating mode, one or more of the following embodiments can be applied to configure a CBSR for one or more TRPs included in the default operating mode: In one embodiment, for the default operating mode, the UE can dynamically (e.g., via DCI) receive a new CBSR configuration for at least one TRP index in the TRP set. The UE can receive indices of one or more DFT beams and / or code points in the Beam Grid (GoB) and one or more thresholds for limiting one or more beams in the GoB. The received new CBSR configuration can be associated with an anchor / primary TRP index in the default operating mode, where the anchor / primary TRP index is the first or last TRP index in the TRP set included in the default operating mode.

[0172] In another embodiment, for the default operating mode, the UE can dynamically receive the indexes of TRPs in the TRP set. The UE can assume that the received TRP indexes are associated with the CBSR configuration received in the CJT operating mode, for example, the CBSR configuration received in the CJT operating mode prior to the default operating mode. In one example, the DFT beam index and threshold configured in the CBSR configuration may be equally valid for the received TRP indexes and / or the indexes of the primary / anchor TRPs.

[0173] In one embodiment, the UE may receive the CBSR configuration of the primary / anchor TRP in the CJT operation mode. The primary / anchor TRP is also included in the default mode. In the default operation mode, the UE may then assume that the CBSR configuration in the CJT mode is valid in the default mode. Alternatively, a separate CBSR may be configured for each TRP in the CJT operation mode, e.g., a separate CBSR configuration is configured for each TRP in the set [TRP1, TRP2, TRP3, TRP4]. In one example, the set of TRPs in the default operation may include TRP2 and TRP4. The UE may assume that the CBSR configured for the TRP (e.g., for TRP2 and TRP4) in the CJT operation mode is valid for the same TRP(s) (e.g., for TRP2 and TRP4) in the default operation mode.

[0174] Management of uplink resources for UCI reporting: In Rel-18 CJT, the UE may select a spatial domain basis across configured TRPs. The UE may also select a frequency domain basis for frequency domain compression. In addition, the UE may also report the indices of the frequency and spatial domain bases of non-zero coefficients. The amount of time and / or frequency domain resources required to report the indices of the frequency and spatial domain bases or the indices of non-zero coefficients is a function of the number of selected spatial domain bases and frequency domain bases. The resources required to report part 2 of the CJT CSI report (see below) are determined by the beta_CSI_Part2 value configured by RRC or DCI. In the case of semi-static configuration in one or more of the following ways, the UE may have excess resources for the second part of the CSI report.

[0175] The UE may be semi-statically configured (e.g., via RRC) to determine and report different numbers of spatial domain bases in the CJT mode and the fallback mode. For example, the UE may be configured to determine the number M1 of spatial domain bases and / or DFT beams in the CJT mode, and the number M2 < M1 of spatial domain bases and / or DFT beams in the fallback mode.

[0176] The UE may be semi-statically configured (e.g., via RRC) to determine and report the same number of spatial domain bases in the CJT mode and the fallback mode.

[0177] For the CJT mode and the fallback mode, the UE may be semi-statically configured (e.g., via RRC) to have a single value of beta_CSI_part2. For example, the UE may be configured with a beta_CSI_part2 value that is valid for both the CJT and fallback modes.

[0178] The UE can be semi-statically (e.g., via RRC) configured to have a first beta_CSI_part2 value for CJT mode and a second beta_CSI_part2 value for fallback mode. In one example, during a burst of DL scheduling intervals, the UE is configured with a first beta_CSI_part2 value for CJT mode and a second beta_CSI_part2 value for all fallback modes.

[0179] When the UE is configured to use the beta_CSI_Part1 value configured for CJT mode in fallback mode, Part 2 of the CSI report may have more resources than required because the bitmap size used to report non-zero coefficients is reduced due to the reduced number of spatial domain bases.

[0180] In one embodiment, the UE can perform one or more of the following operations in fallback mode.

[0181] The UE can determine to report Group 1 Part 2 of the CSI report completely, and if some resources are remaining, the UE can determine to report one or more elements in Group 1 Part 2 repeatedly (e.g., report the broadband coefficient, subband coefficient, phase coefficient, etc. repeatedly in the same CSI report).

[0182] The UE can determine that the report of Group 0 Part 2 is complete, and then repeat the report of Group 0 Part 2 for the purpose of enhancing reliability.

[0183] The UE can use excess resources to report determined time and frequency synchronization measurements at a higher granularity. In one example, the UE can utilize excess resources to repeat the reporting of time and frequency synchronization measurements.

[0184] The UE can report groups 0, 1, and 2 in their entirety, and if resources are still available, the UE can rereport group 0 in its entirety and / or rereport all or part of group 2 in its entirety.

[0185] Description of Parts 1 and 2 of the CSI report: The CSI report has two parts, namely Part 1 and Part 2. Part 2 of the CSI report is further divided into three groups, namely Group 0, 1, and 2. In the current system (i.e., Rel-17 / 18), the UE reports Group 0 with a higher priority than Group 1 and 2, and reports Group 1 with a higher priority than Group 2.

[0186] TRP calibration process based on triggered SRS Figure 4 A method according to a first embodiment of this principle is shown, which has implicit relative time / frequency error reporting using special SRS transmission.

[0187] In step S410, the UE is configured for CJT operation and is configured to perform TRP frequency / timing-related measurements using the RS configured per TRP. The TRP is indicated / configured as a reference / anchor TRP. The UE is configured with a set of SRS resources, where each SRS resource is associated with an SRI, and each SRI is associated with a TRP index.

[0188] In step S420, the UE performs a frequency / timing error measurement on each TRP pair including a first TRP and a second TRP, wherein (e.g., for each pair) the first TRP may be an anchor / reference TRP.

[0189] In step S430, when the difference exceeds a configured threshold, the UE can tag / indicate to the network the excessive relative frequency / timing error between the first and second measured TRPs. The UE can also indicate the TRP index of the second TRP.

[0190] Following the transmission frequency / timing error indication, in step S440, the UE may receive a "Special Calibration SRS" transmission request. The SRS request DCI may include at least one of the following: an "SRS calibration indication flag" and an SRI corresponding to the second TRP, an SRI corresponding to the SRS resource associated with the second TRP, a TCI state associated with the first TRP (e.g., a reference / anchor TRP), and a set of N SRIs corresponding to the respective N SRS resources associated with the corresponding TRP for each SRS resource.

[0191] In response to receiving a special SRS request, in step S450, the UE may use the frequency and timing associated with the first TRP (e.g., reference TRP) to transmit the first SRS in the resources associated with the first TRP (e.g., reference TRP).

[0192] In response to receiving a special SRS request, in step S460, the UE may also transmit a second SRS using the indicated SRS resources and adjusting the transmission time and / or frequency based on the measurement time and / or frequency error determined for the second TRP relative to the first TRP. If a set of N SRIs is indicated to the UE in the SRS calibration request, the UE may transmit SRS in each of the SRS resources corresponding to the N SRIs, wherein the time and / or frequency of each SRS transmission is adjusted based on the measurement time and / or frequency error for the corresponding TRP relative to the reference / first TRP. The SRS transmission or the N SRS transmissions may be based on the indicated TCI state (e.g., a spatial filter based on the indicated TCI state may be used).

[0193] In one embodiment, the UE receives configuration information for operation in CJT mode, wherein the configuration may include at least one or more of the following: This configuration may include the number of TRP candidates considered for CJT operations, from which a subset of TRPs can be selected for transmission.

[0194] Based on this configuration, there may be at least one TCI state or downlink reference signal associated with each TRP.

[0195] Furthermore, the configuration may include at least one SRS resource set, wherein each SRS resource identified by the SRI may be associated with one of the configured TRPs in the CJT set. The SRS configuration may also include information about some pre-configured transmission opportunities, such as periodicity patterns, configuration modes, etc.

[0196] This configuration may include configuration performance metric thresholds that can be used to trigger frequency and / or measure, which may be based on one or more of the following.

[0197] This configuration may include configuration thresholds for checking relative frequency timing errors (multiple).

[0198] This configuration may include configuration thresholds for checking relative frequency errors (multiple).

[0199] This configuration may include configuration thresholds for checking error vector magnitude (EVM) errors.

[0200] This configuration may include configuration thresholds for system performance, such as representative indicators of RSRP, capacity, throughput, BLER, etc.

[0201] This configuration may include time-related information for determining frequency and / or timing error measurement opportunities, such as period, timer, etc.

[0202] This configuration may include one or more uplink resources for reporting information related to frequency and / or timing errors, wherein each uplink resource may be associated with one or more TRPs. Uplink resources can be used to indicate TRPs with excessive errors, or to indicate partial information related to frequency / time errors, such as time-only or frequency-only errors.

[0203] In one embodiment, using at least one of the downlink reference signals configured for each TRP, the UE can perform frequency and / or timing measurements to determine the relative frequency and / or timing error of each TRP relative to a reference TRP (e.g., anchor / serving TRP). The UE can perform the measurements based on one or more of the following.

[0204] This measurement can be based on non-periodic / semi-continuous triggering, such as performance metrics, load balancing, etc., and gNB can indicate the execution frequency and / or timing error measurement.

[0205] The measurement can be based on a deterministic pattern, for example, the UE can be configured with periodic, timer or predefined measurement opportunities (e.g. time pattern) to perform frequency and / or timing error measurements.

[0206] This measurement can be based on system reconfiguration, such as reconfiguration of the TRP candidate set in CJT configuration, carrier, bandwidth portion (BWP), etc.

[0207] This measurement can be based on performance metrics, such as when the UE observes that downlink performance has deteriorated and downlink performance metrics (e.g., the number of NACKs, measured RSRP, etc.) have met the configured thresholds.

[0208] In one embodiment, once the UE has performed a frequency / timing error measurement, if the measured error exceeds a configured threshold, the UE can indicate a TRP index associated with the excessive error. The indication of a TRP with excessive frequency / timing error can be done by indicating an index associated with a downlink or uplink reference signal. In one solution, the UE can also indicate the measured frequency or time error associated with the TRP.

[0209] Figure 5 The principle of a special calibration SRS transmission based on this principle is illustrated. In one embodiment, after determining the excessive frequency / time error exhibited by the second TRP relative to the first TRP (i.e., the reference TRP), the UE may receive a dynamic indication as a "special calibration SRS" transmission request. The dynamic indication (e.g., DCI) may include one or more of the following.

[0210] The indication flag corresponding to the second TRP exhibiting excessive relative time / frequency error can be the TCI status or SRI associated with the second TRP.

[0211] The SRI corresponding to the SRS resource associated with the second TRP. In one embodiment, when the second TRP is detected to exhibit excessive relative time / frequency error, the UE may receive a set of N SRIs corresponding to the corresponding N SRS resources, where each SRS resource is associated with a corresponding TRP.

[0212] The TCI state associated with the first TRP (e.g., reference / anchor TRP).

[0213] When the UE receives a "Special Calibration SRS" request, the UE may perform one or more of the following operations.

[0214] The UE may use the SRS resources associated with the first TRP (e.g., reference TRP) to transmit the first SRS. The transmission may be based on the frequency and timing associated with the first (e.g., reference TRP) TRP.

[0215] If a Special Calibration SRS request indicates a single SRI, the UE can use the indicated SRS resource to send a second SRS to, for example, a first TRP. The transmission of the second SRS can be based on the frequency and timing associated with the second TRP.

[0216] If the "Special Calibration SRS" request indicates more than one SRI, such as N SRIs, the UE can use N SRS resources corresponding to the N SRIs to transmit N SRSs, where the transmission of each SRS resource can be based on the frequency and timing associated with each corresponding TRP.

[0217] In an alternative embodiment, the UE may use a pre-configured transmission opportunity to begin transmitting a “Special Calibration SRS” without receiving a “Special Calibration SRS” request, as explained above.

[0218] Solution Summary In one embodiment, a method at a wireless transmit / receive unit (WTRU) includes: receiving information indicating a configuration for joint reception from a plurality of transmission points, including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmitting information indicating the relative error of the measurement associated with the reference signal received from the at least one pair of transmission points; receiving information indicating at least one scheduled downlink gap; measuring received signals from the reference transmission point or a subset of the plurality of transmission points during the at least one scheduled downlink gap; and measuring received signals from the plurality of transmission points after the at least one scheduled downlink gap.

[0219] Relative error can be related to at least one of time error and frequency error.

[0220] The measurement of relative error can be periodic.

[0221] The measurement of relative error can be non-periodic.

[0222] The at least one pair of transmission points may include a reference transmission point.

[0223] The downlink gaps that are scheduled can be a single gap or a series of gaps.

[0224] The subset can satisfy at least one configuration condition, including time error within the indicated range, frequency error within the indicated range, and error rate below the indicated value.

[0225] Measuring received signals from at least one of a reference transmission point and a subset of the plurality of transmission points may include measuring channel state information of the plurality of transmission points and measuring at least one of a reference signal associated with the plurality of transmission points.

[0226] Measuring received signals from the plurality of transmission points may include measuring channel state information of the plurality of transmission points and measuring at least one of a reference signal associated with the plurality of transmission points.

[0227] The method may also include measuring relative error.

[0228] In one embodiment, a wireless transmit / receive unit (WTRU) includes: at least one processor configured to receive information indicating a configuration for joint reception from a plurality of transmission points, including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmit information indicating the relative error of the measurement associated with the reference signal received from the at least one pair of transmission points; receive information indicating at least one scheduled downlink gap; measure received signals from the reference transmission point or a subset of the plurality of transmission points during the at least one scheduled downlink gap; and measure received signals from the plurality of transmission points after the at least one scheduled downlink gap.

[0229] Relative error can be related to at least one of time error and frequency error.

[0230] The measurement of relative error can be periodic.

[0231] The measurement of relative error can be non-periodic.

[0232] The at least one pair of transmission points may include a reference transmission point.

[0233] The downlink gaps that are scheduled can be a single gap or a series of gaps.

[0234] The subset can satisfy at least one configuration condition, including time error within the indicated range, frequency error within the indicated range, and error rate below the indicated value.

[0235] Measuring received signals from at least one of a reference transmission point and a subset of the plurality of transmission points may include measuring channel state information of the plurality of transmission points and measuring at least one of a reference signal associated with the plurality of transmission points.

[0236] Measuring received signals from the plurality of transmission points may include measuring channel state information of the plurality of transmission points and measuring at least one of a reference signal associated with the plurality of transmission points.

[0237] The at least one processor can also be configured to measure relative error.

[0238] In one embodiment, a method at a wireless transmit / receive unit (WTRU) includes: receiving information indicating a configuration for joint reception from a plurality of transmission points, including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmitting information indicating the relative error of the measurement associated with the reference signal received from the at least one pair of transmission points; receiving information indicating at least one scheduled downlink gap; measuring received signals from the reference transmission point or a subset of the plurality of transmission points during the at least one scheduled downlink gap; and monitoring a channel search space associated with the plurality of transmission points after the at least one scheduled downlink gap.

[0239] Relative error can be related to at least one of time error and frequency error.

[0240] The measurement of relative error can be periodic.

[0241] The measurement of relative error can be non-periodic.

[0242] The at least one pair of transmission points may include a reference transmission point.

[0243] The downlink gaps that are scheduled can be a single gap or a series of gaps.

[0244] The subset can satisfy at least one configuration condition, including time error within the indicated range, frequency error within the indicated range, and error rate below the indicated value.

[0245] The method may also include measuring relative error.

[0246] In one embodiment, a wireless transmit / receive unit (WTRU) includes: at least one processor configured to receive information indicating a configuration for joint reception from a plurality of transmission points including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmit information indicating the relative error of the measurement associated with the reference signal received from the at least one pair of transmission points; receive information indicating at least one scheduled downlink gap; measure received signals from the reference transmission point or a subset of the plurality of transmission points during the at least one scheduled downlink gap; and monitor a channel search space associated with the plurality of transmission points after the at least one scheduled downlink gap.

[0247] Relative error can be related to at least one of time error and frequency error.

[0248] The measurement of relative error can be periodic.

[0249] The measurement of relative error can be non-periodic.

[0250] The at least one pair of transmission points may include a reference transmission point.

[0251] The downlink gaps that are scheduled can be a single gap or a series of gaps.

[0252] The subset can satisfy at least one configuration condition, including time error within the indicated range, frequency error within the indicated range, and error rate below the indicated value.

[0253] The at least one processor can also be configured to measure relative error.

[0254] In one embodiment, a method at a wireless transmit / receive unit (WTRU) includes: receiving information indicating a configuration for joint reception from a plurality of transmission points including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmitting information indicating the measured relative error associated with the reference signal received from the at least one pair of transmission points; transmitting information indicating an excess of a relative error when it is determined that the relative error exceeds a given value; receiving information indicating a request to transmit a calibration signal to at least one of the plurality of transmission points; and transmitting the calibration signal according to the request.

[0255] Information indicating an excess relative error may include the identifier of at least one transmission point in the corresponding transmission point pair.

[0256] The request may include at least one of an indicator of a reference signal corresponding to one of a pair of transmission points whose relative error exceeds a given value and a TCI state associated with the reference transmission point.

[0257] The calibration signal can be transmitted to the reference transmission point.

[0258] The calibration signal can be transmitted to a transmission point that is not a reference transmission point, wherein at least one of the time or frequency of the calibration signal is based on a relative error.

[0259] In one embodiment, a wireless transmit / receive unit (WTRU) includes: at least one processor configured to receive information indicating configuration for joint reception from a plurality of transmission points including a reference transmission point, and for reporting a measurement of a relative error associated with a reference signal received from at least one pair of the plurality of transmission points; transmit information indicating the measured relative error associated with the reference signal received from the at least one pair of transmission points; transmit information indicating an excess of a relative error when it is determined that the relative error exceeds a given value; receive information indicating a request to transmit a calibration signal to at least one of the plurality of transmission points; and transmit the calibration signal according to the request.

[0260] Information indicating an excess relative error may include the identifier of at least one transmission point in the corresponding transmission point pair.

[0261] The request may include at least one of an indicator of a reference signal corresponding to one of a pair of transmission points whose relative error exceeds a given value and a TCI state associated with the reference transmission point.

[0262] The calibration signal can be transmitted to the reference transmission point.

[0263] The calibration signal can be transmitted to a transmission point that is not a reference transmission point, wherein at least one of the time or frequency of the calibration signal is based on a relative error.

[0264] in conclusion.

[0265] Although features and elements have been provided above in specific combinations, those skilled in the art will appreciate that each feature or element can be used alone or in any combination with other features and elements. This disclosure is not limited to the specific embodiments described herein, which are intended to illustrate various aspects. Many modifications and variations can be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. No element, action, or instruction used in the description of this application should be construed as critical or essential to the invention unless explicitly provided so. Based on the foregoing description, functionally equivalent methods and apparatuses within the scope of this disclosure will be apparent to those skilled in the art, in addition to those methods and apparatuses listed herein. Such modifications and variations are intended to fall within the scope of the appended claims. This disclosure is limited only by the terms of the appended claims together with the full scope of the equivalents granted by such claims. It will be understood that this disclosure is not limited to specific methods or systems.

[0266] For simplicity, the foregoing embodiments are discussed in terms of the terminology and structure of devices with wireless communication capabilities (i.e., radio wave transmitters and receivers). However, the embodiments discussed are not limited to these systems, but can be applied to other systems that use other forms of electromagnetic waves or non-electromagnetic waves (such as sound waves).

[0267] It will also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the term “video” or the term “image” may mean any of a snapshot, a single image, and / or multiple images displayed on a time basis. As another example, when referred to herein, the term “user equipment” and its abbreviation “UE,” the term “remote,” and / or the term “head-mounted display” and its abbreviation “HMD” may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of several embodiments of a WTRU; (iii) a device with wireless and / or wired capabilities (e.g., tetherable), particularly configured with some or all of the constructs and functionalities of a WTRU; (iii) a device with wireless and / or wired capabilities configured with fewer than all the constructs and functionalities of a WTRU; or (iv) something like that. Figure 1A-1D Details of an example WTRU, which may represent any WTRU described herein, are provided. As another example, the various embodiments disclosed above and below are described as utilizing a head-mounted display. Those skilled in the art will recognize that devices other than head-mounted displays can be utilized, and some or all of this disclosure and the various disclosed embodiments can be modified accordingly without excessive experimentation. Examples of such other devices may include drones or other devices configured to stream information to provide an adaptive, realistic experience.

[0268] Furthermore, the methods provided herein can be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROMs and digital multifunction discs (DVDs). The processor associated with the software can be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC, or any host.

[0269] Variations of the methods, apparatus, and systems provided above are possible without departing from the scope of the invention. Given the wide variety of applicable embodiments, it should be understood that the illustrated embodiments are merely examples and should not be construed as limiting the scope of the appended claims. For example, embodiments provided herein include handheld devices that may include or be used with any suitable voltage source, such as a battery, that provides any suitable voltage.

[0270] Furthermore, in the embodiments provided above, processing platforms, computing systems, controllers, and other devices including processors are indicated. These devices may include at least one central processing unit (“CPU”) and memory. According to the practice of those skilled in the art of computer programming, references to actions and symbolic representations of operations or instructions can be executed by various CPUs and memories. Such actions and operations or instructions may be referred to as “executed,” “computer-executed,” or “CPU-executed.”

[0271] Those skilled in the art will appreciate that the actions and symbolic representations of operations or instructions include the CPU's manipulation of electrical signals. Electrical systems represent data bits that can cause a final conversion or reduction of electrical signals and are maintained at memory locations in a memory system, thereby reconfiguring or otherwise altering the operation of the CPU and other signal processing. The memory location maintaining the data bits is a physical location having specific electrical, magnetic, optical, or organic properties corresponding to or representing the data bits. It should be understood that the embodiments are not limited to the platforms or CPUs mentioned above, and other platforms and CPUs may support the provided methods.

[0272] Data bits can also be maintained on a computer-readable medium, including disks, optical disks, and any other CPU-readable volatile (e.g., random access memory (RAM)) or non-volatile (e.g., read-only memory (ROM)) mass storage system. The computer-readable medium can include cooperative or interconnected computer-readable media that reside exclusively on a processing system or are distributed across multiple interconnected processing systems, which can be located locally or remotely. It should be understood that the embodiments are not limited to the memories mentioned above, and other platforms and memories can support the provided methods.

[0273] In the illustrative embodiments, any operations, processes, etc., described herein may be implemented as computer-readable instructions stored on a computer-readable medium. These computer-readable instructions may be executed by a processor of a mobile unit, network element, and / or any other computing device.

[0274] There is little difference between the hardware and software implementations of various aspects of the system. The use of hardware or software is often (but not always; in some contexts, the choice between hardware and software may become important) a design choice representing a cost-efficiency trade-off. Various means can be available to implement the processes and / or systems and / or other technologies (e.g., hardware, software, and / or firmware) described herein, and the preferred means can vary depending on the context in which the processes and / or systems and / or other technologies are deployed. For example, if the implementer determines that speed and accuracy are paramount, the implementer may choose a primarily hardware and / or firmware-based approach. If flexibility is paramount, the implementer may choose a primarily software-based approach. Alternatively, the implementer may choose some combination of hardware, software, and / or firmware.

[0275] The foregoing detailed description has illustrated various embodiments of the apparatus and / or processes using block diagrams, flowcharts, and / or examples. As such block diagrams, flowcharts, and / or examples encompass one or more functions and / or operations, those skilled in the art will understand that each function and / or operation within such block diagrams, flowcharts, or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, several portions of the subject matter described herein can be implemented via application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integration formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein can be implemented, in whole or in part, equivalently in an integrated circuit, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or virtually any combination thereof, and that designing the circuit system and / or writing code for the software and / or firmware according to this disclosure will be entirely within the skill of those skilled in the art. Furthermore, those skilled in the art will appreciate that the mechanisms of the subject matter described herein can be distributed as a variety of program products, and that the illustrative embodiments of the subject matter described herein are applicable regardless of the specific type of signal-bearing medium used for the actual implementation of the distribution. Examples of signal-bearing media include, but are not limited to, recordable media such as floppy disks, hard disk drives, CDs, DVDs, digital magnetic tapes, computer memory, etc., and transmission media such as digital and / or analog communication media (e.g., optical fibers, waveguides, wired communication links, wireless communication links, etc.).

[0276] Those skilled in the art will recognize that it is common practice in the art to describe devices and / or processes in the manner set forth herein, and then to integrate such described devices and / or processes into data processing systems using engineering practice. That is, at least a portion of the devices and / or processes described herein can be integrated into a data processing system through a reasonable amount of experimentation. Those skilled in the art will recognize that a typical data processing system typically includes one or more system unit housings, video display devices, memories such as volatile and non-volatile memories, processors such as microprocessors and digital signal processors, computing entities such as operating systems, drivers, graphical user interfaces, and applications, one or more interactive devices such as touchpads or screens, and / or control systems including feedback loops and control motors (e.g., feedback for listening to position and / or speed, control motors for moving and / or adjusting components and / or quantities). Typical data processing systems can be implemented using any suitable commercially available components, such as those commonly found in data computing / communication and / or network computing / communication systems.

[0277] The topics described herein sometimes illustrate different components included within or connected to different other components. It will be understood that the architectures depicted are merely examples, and many other architectures can indeed be implemented to achieve the same functionality. Conceptually, any arrangement of components that achieve the same functionality is effectively “associated” to achieve the desired functionality. Therefore, any two components combined in this document to achieve a particular functionality can be considered “associated” with each other to achieve the desired functionality, regardless of the architecture or intermediate components. Similarly, any two components so associating can also be considered “operably connected” or “operably coupled” to each other to achieve the desired functionality, and any two components that can be so associating can also be considered “operably coupled” to each other to achieve the desired functionality. Specific examples of operational coupling include, but are not limited to, physically matable and / or physically interactive components and / or wirelessly interactive and / or logically interactive components.

[0278] Regarding the use of virtually any plural and / or singular terms in this document, those skilled in the art may appropriately translate from plural to singular and / or from singular to plural depending on the context and / or application. For clarity, various singular / multiple permutations may be clearly illustrated herein.

[0279] Those skilled in the art will understand that, generally, the terminology used herein, and especially in the appended claims (e.g., the body of the appended claims), is intended to be “open” terms (e.g., the term “comprising” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “at least having,” the term “comprising” should be interpreted as “including but not limited to,” etc.). Those skilled in the art will further understand that if there is an intent to introduce a particular number of claims, such intent will be explicitly stated in the claims, and if there is no such statement, such intent does not exist. For example, in cases where only one item is intended, the term “single” or similar language may be used. To aid understanding, the appended claims and / or the description herein may include the use of introductory phrases “at least one” and “one or more” to introduce claims. However, the use of such phrases should not be construed as implying that a claim introduced by the indefinite article “a” or “an” will limit any particular claim to include only one such embodiment, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should be interpreted as meaning “at least one” or “one or more”). The same applies to the use of definite articles used to introduce the claims. Furthermore, even if a specific number of claims is explicitly stated, those skilled in the art will recognize that such a statement should be interpreted as meaning at least the number stated (e.g., a simple statement of “two statements” without other modifiers means at least two statements, or two or more statements). Furthermore, in cases similar to the use of the convention "at least one of A, B, and C," generally, such a structure is intended to mean that a person skilled in the art will understand the convention (e.g., "a system having at least one of A, B, and C" will include, but is not limited to, systems having a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In cases similar to the use of the convention "at least one of A, B, or C," generally, such a structure is intended to mean that a person skilled in the art will understand the convention (e.g., "a system having at least one of A, B, or C" will include, but is not limited to, systems having a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). Those skilled in the art will further understand that any separating words and / or phrases that actually represent two or more optional terms, whether in the specification, claims, or drawings, should be understood to envision the possibility of including one term, one term, or two terms. For example, the phrase “A or B” would be understood to include the possibility of “A” or “B” or “A and B”.Furthermore, as used herein, the term "any" followed by a list of multiple items and / or multiple item categories is intended to include, individually or in combination with other items and / or other item categories, "any one," "any combination," "any multiple," and / or "any combination of multiples." Additionally, as used herein, the term "set" is intended to include any number of items, including zero. Furthermore, as used herein, the term "quantity" is intended to include any quantity, including zero. And as used herein, the term "multiple" is intended to be synonymous with "multiple."

[0280] Furthermore, when features or aspects of this disclosure are described in accordance with the Markush Group, those skilled in the art will recognize that this disclosure is also described in accordance with any individual member or subgroup of the Markush Group.

[0281] As those skilled in the art will understand, for any and all purposes, such as for providing a written description, all scopes disclosed herein also include any and all possible subscopes and combinations thereof. Any listed scope can be readily considered sufficiently descriptive and enables the decomposition of the same scope into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each scope discussed herein can be readily decomposed into a lower third, a middle third, and an upper third, etc. As those skilled in the art will also understand, all language such as “up to,” “at least,” “greater than,” “less than,” etc., includes the listed numbers and refers to a scope that can subsequently be decomposed into subscopes as discussed above. Finally, as those skilled in the art will understand, a scope includes members of each individual. Thus, for example, a group having 1-3 units means a group having 1, 2, or 3 units. Similarly, a group having 1-5 units means a group having 1, 2, 3, 4, or 5 units, and so on.

[0282] Furthermore, the claims should not be construed as limited to the order or elements provided, unless otherwise stated. Additionally, the use of the term "means for..." in any claim is intended to refer to... The claim format is either device plus function, and any claim without the term "device for..." is not intended to be so.

Claims

1. A method at a wireless transmit / receive unit (WTRU), the method comprising: Receive information indicating a configuration for joint reception from multiple transmission points including a reference transmission point, and for reporting a measurement of the relative error associated with a reference signal received from at least one pair of the multiple transmission points; The transmission indicates information about the relative measurement error associated with the reference signal received from the at least one pair of transmission points; When it is determined that the relative measurement error exceeds a given value, the transmission indicates that the relative measurement error exceeds the information. Receive information indicating a request to transmit a calibration signal to at least one of the plurality of transmission points; as well as A calibration signal is transmitted in accordance with the request.

2. The method of claim 1, wherein the relative error is related to at least one of time error and frequency error.

3. The method according to claim 1 or 2, wherein the measurement of the relative error is periodic.

4. The method according to claim 1 or 2, wherein the measurement of the relative error is non-periodic.

5. The method according to any one of claims 1-4, wherein the at least one pair of transmission points includes a reference transmission point.

6. The method according to any one of claims 1-5 further includes measuring relative error.

7. A wireless transmit / receive unit (WTRU) comprising at least one processor configured to: Receive information indicating a configuration for joint reception from multiple transmission points including a reference transmission point, and for reporting a measurement of the relative error associated with a reference signal received from at least one pair of the multiple transmission points; When it is determined that the relative measurement error exceeds a given value, the transmission indicates that the relative measurement error exceeds the information. Receive information indicating a request to transmit a calibration signal to at least one of the plurality of transmission points; as well as A calibration signal is transmitted in accordance with the request.

8. The WTRU of claim 7, wherein the relative error is related to at least one of time error and frequency error.

9. The WTRU according to claim 7 or 8, wherein, The at least one processor is configured to perform periodic measurements of relative error.

10. The WTRU according to claim 7 or 8, wherein, The at least one processor is configured to perform non-periodic measurements of relative error.

11. The WTRU according to any one of claims 7-10, wherein, The at least one pair of transmission points includes a reference transmission point.

12. The WTRU according to any one of claims 7-11, wherein, The at least one processor is also configured to measure relative error.

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