WO2022043918A1

WO2022043918A1 - Configuration based on two tracking reference signals

Info

Publication number: WO2022043918A1
Application number: PCT/IB2021/057839
Authority: WO
Inventors: Vijay Nangia; Ahmed Monier Ibrahim Saleh HINDY
Original assignee: Lenovo Singapore Pte Ltd
Current assignee: Lenovo Singapore Pte Ltd
Priority date: 2020-08-28
Filing date: 2021-08-26
Publication date: 2022-03-03
Anticipated expiration: 2023-02-28

Abstract

Apparatuses, methods, and systems are disclosed for configuration based on two tracking reference signals. One method (1100) includes receiving (1102), at a user equipment, DCI that schedules a downlink transmission. The DCI includes a TCI codepoint that corresponds to two TCI states associated with at least two network nodes; the DCI includes information corresponding to at least one DMRS port; and the at least one DMRS port corresponds to at least one layer of a PDSCH transmission. The method (1100) includes receiving (1104) at least two TRS. A first TCI state of the two TCI states corresponds to a first TRS; the first TRS is a first source reference signal; a second TCI state of the two TCI states corresponds to a second TRS; and the second TRS is a second source reference signal.

Description

CONFIGURATION BASED ON TWO TRACKING REFERENCE SIGNALS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to United States Patent Application Serial Number 63/071,987 entitled “APPARATUSES, METHODS, AND SYSTEMS FOR FURTHER ENHANCEMENTS FOR HIGH SPEED SCENARIOS UNDER SIGNAL FREQENCY NETWORKS” and fried on August 28, 2020 for Vijay Nangia, which is incorporated herein by reference in its entirety.

FIELD

[0002] The subject matter disclosed herein relates generally to wireless communications and more particularly relates to configuration based on two tracking reference signals.

BACKGROUND

[0003] In certain wireless communications networks, high speed trains and/or high speed vehicles may be used. In such networks, certain transmissions may not be synchronized.

BRIEF SUMMARY

[0004] Methods for configuration based on two tracking reference signals are disclosed. Apparatuses and systems also perform the functions of the methods. One embodiment of a method includes receiving, at a user equipment, downlink control information that schedules a downlink transmission. The downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission. In some embodiments, the method includes receiving at least two tracking reference signals from the at least two network nodes. In certain embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port. [0005] One apparatus for configuration based on two tracking reference signals includes a user equipment. In some embodiments, the apparatus includes a receiver that: receives downlink control information that schedules a downlink transmission, wherein: the downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and receives at least two tracking reference signals from the at least two network nodes. In various embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0006] Another embodiment of a method for configuration based on two tracking reference signals includes transmitting, from a network unit, downlink control information that schedules a downlink transmission. The downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission. In some embodiments, the method includes transmitting at least two tracking reference signals from the at least two network nodes. In certain embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port. [0007] Another apparatus for configuration based on two tracking reference signals includes a network unit. In some embodiments, the apparatus includes a transmitter that: transmits downlink control information that schedules a downlink transmission, wherein: the downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and transmits at least two tracking reference signals from the at least two network nodes. In various embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0009] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for configuration based on two tracking reference signals;

[0010] Figure 2 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for configuration based on two tracking reference signals;

[0011] Figure 3 is a schematic block diagram illustrating one embodiment of an apparatus that may be used for configuration based on two tracking reference signals;

[0012] Figure 4 is a schematic block diagram illustrating one embodiment of a system having a high speed train;

[0013] Figure 5 is a schematic block diagram illustrating one embodiment of a system for configured with two TRSs for TRP1 and TRP2 synchronization; [0014] Figure 6 is a schematic block diagram illustrating one embodiment of a DMRS pattern for a front loaded DMRS with a single symbol and one additional symbol;

[0015] Figure 7 is a schematic block diagram illustrating one embodiment of a DMRS pattern for a front loaded DMRS with a single symbol and three additional symbols;

[0016] Figure 8 is a schematic block diagram illustrating one embodiment of DMRS REs from different DMRS symbols for channel estimation;

[0017] Figure 9 is a schematic block diagram illustrating one embodiment of a single DCI scheduling for two minislots;

[0018] Figure 10 is a schematic block diagram illustrating one embodiment of a single DCI scheduling for two PDSCHs;

[0019] Figure 11 is a flow chart diagram illustrating one embodiment of a method for configuration based on two tracking reference signals; and

[0020] Figure 12 is a flow chart diagram illustrating another embodiment of a method for configuration based on two tracking reference signals.

DETAILED DESCRIPTION

[0021] As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and/or program code, referred hereafter as code. The storage devices may be tangible, non-transitory, and/or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code.

[0022] Certain of the functional units described in this specification may be labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration (“VLSI”) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[0023] Modules may also be implemented in code and/or software for execution by various types of processors. An identified module of code may, for instance, include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may include disparate instructions stored in different locations which, when joined logically together, include the module and achieve the stated purpose for the module.

[0024] Indeed, a module of code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different computer readable storage devices. Where a module or portions of a module are implemented in software, the software portions are stored on one or more computer readable storage devices.

[0025] Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0026] More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (“RAM”), a read-only memory (“ROM”), an erasable programmable read-only memory (“EPROM” or Flash memory), a portable compact disc readonly memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0027] Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the "C" programming language, or the like, and/or machine languages such as assembly languages. The code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (“LAN”) or a wide area network (“WAN”), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0028] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.

[0029] Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment.

[0030] Aspects of the embodiments are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by code. The code may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the fiinctions/acts specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

[0031] The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.

[0032] The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

[0033] The schematic flowchart diagrams and/or schematic block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods and program products according to various embodiments. In this regard, each block in the schematic flowchart diagrams and/or schematic block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function(s).

[0034] It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures.

[0035] Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code.

[0036] The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements. [0037] Figure 1 depicts an embodiment of a wireless communication system 100 for configuration based on two tracking reference signals. In one embodiment, the wireless communication system 100 includes remote units 102 and network units 104. Even though a specific number of remote units 102 and network units 104 are depicted in Figure 1, one of skill in the art will recognize that any number of remote units 102 and network units 104 may be included in the wireless communication system 100.

[0038] In one embodiment, the remote units 102 may include computing devices, such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), aerial vehicles, drones, or the like. In some embodiments, the remote units 102 include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units 102 may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, UE, user terminals, a device, or by other terminology used in the art. The remote units 102 may communicate directly with one or more of the network units 104 via UL communication signals. In certain embodiments, the remote units 102 may communicate directly with other remote units 102 via sidelink communication.

[0039] The network units 104 may be distributed over a geographic region. In certain embodiments, a network unit 104 may also be referred to and/or may include one or more of an access point, an access terminal, a base, a base station, a location server, a core network (“CN”), a radio network entity, a Node-B, an evolved node-B (“eNB”), a 5G node-B (“gNB”), a Home Node-B, a relay node, a device, a core network, an aerial server, a radio access node, an access point (“AP”), new radio (“NR”), a network entity, an access and mobility management function (“AMF”), a unified data management (“UDM”), a unified data repository (“UDR”), a UDM/UDR, a policy control function (“PCF”), a radio access network (“RAN”), a network slice selection function (“NSSF”), an operations, administration, and management (“0AM”), a session management function (“SMF”), a user plane function (“UPF”), an application function, an authentication server function (“AUSF”), security anchor functionality (“SEAF”), trusted non- 3GPP gateway function (“TNGF”), or by any other terminology used in the art. The network units 104 are generally part of a radio access network that includes one or more controllers communicably coupled to one or more corresponding network units 104. The radio access network is generally communicably coupled to one or more core networks, which may be coupled to other networks, like the Internet and public switched telephone networks, among other networks. These and other elements of radio access and core networks are not illustrated but are well known generally by those having ordinary skill in the art.

[0040] In one implementation, the wireless communication system 100 is compliant with NR protocols standardized in third generation partnership project (“3GPP”), wherein the network unit 104 transmits using an OFDM modulation scheme on the downlink (“DL”) and the remote units 102 transmit on the uplink (“UL”) using a single-carrier frequency division multiple access (“SC-FDMA”) scheme or an orthogonal frequency division multiplexing (“OFDM”) scheme. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocol, for example, WiMAX, institute of electrical and electronics engineers (“IEEE”) 802.11 variants, global system for mobile communications (“GSM”), general packet radio service (“GPRS”), universal mobile telecommunications system (“UMTS”), long term evolution (“LTE”) variants, code division multiple access 2000 (“CDMA2000”), Bluetooth®, ZigBee, Sigfoxx, among other protocols. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0041] The network units 104 may serve a number of remote units 102 within a serving area, for example, a cell or a cell sector via a wireless communication link. The network units 104 transmit DL communication signals to serve the remote units 102 in the time, frequency, and/or spatial domain.

[0042] In various embodiments, a remote unit 102 may receive, at a user equipment, downlink control information that schedules a downlink transmission. The downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission. In some embodiments, the remote unit 102 may receive at least two tracking reference signals from the at least two network nodes. In certain embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port. Accordingly, the remote unit 102 may be used for configuration based on two tracking reference signals.

[0043] In certain embodiments, a network unit 104 may transmit downlink control information that schedules a downlink transmission. The downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission. In some embodiments, the network unit 104 may transmit at least two tracking reference signals from the at least two network nodes. In certain embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port. Accordingly, the network unit 104 may be used for configuration based on two tracking reference signals.

[0044] Figure 2 depicts one embodiment of an apparatus 200 that may be used for configuration based on two tracking reference signals. The apparatus 200 includes one embodiment of the remote unit 102. Furthermore, the remote unit 102 may include a processor 202, a memory 204, an input device 206, a display 208, a transmitter 210, and a receiver 212. In some embodiments, the input device 206 and the display 208 are combined into a single device, such as a touchscreen. In certain embodiments, the remote unit 102 may not include any input device 206 and/or display 208. In various embodiments, the remote unit 102 may include one or more of the processor 202, the memory 204, the transmitter 210, and the receiver 212, and may not include the input device 206 and/or the display 208.

[0045] The processor 202, in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor 202 may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor 202 executes instructions stored in the memory 204 to perform the methods and routines described herein. The processor 202 is communicatively coupled to the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212.

[0046] The memory 204, in one embodiment, is a computer readable storage medium. In some embodiments, the memory 204 includes volatile computer storage media. For example, the memory 204 may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory 204 includes non-volatile computer storage media. For example, the memory 204 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 204 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 204 also stores program code and related data, such as an operating system or other controller algorithms operating on the remote unit 102.

[0047] The input device 206, in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device 206 may be integrated with the display 208, for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device 206 includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device 206 includes two or more different devices, such as a keyboard and a touch panel.

[0048] The display 208, in one embodiment, may include any known electronically controllable display or display device. The display 208 may be designed to output visual, audible, and/or haptic signals. In some embodiments, the display 208 includes an electronic display capable of outputting visual data to a user. For example, the display 208 may include, but is not limited to, a liquid crystal display (“LCD”), a light emitting diode (“LED”) display, an organic light emitting diode (“OLED”) display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the display 208 may include a wearable display such as a smart watch, smart glasses, a heads-up display, or the like. Further, the display 208 may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

[0049] In certain embodiments, the display 208 includes one or more speakers for producing sound. For example, the display 208 may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the display 208 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the display 208 may be integrated with the input device 206. For example, the input device 206 and display 208 may form a touchscreen or similar touch-sensitive display. In other embodiments, the display 208 may be located near the input device 206.

[0050] In certain embodiments, the receiver 212: receives downlink control information that schedules a downlink transmission, wherein: the downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and receives at least two tracking reference signals from the at least two network nodes. In various embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0051] Although only one transmitter 210 and one receiver 212 are illustrated, the remote unit 102 may have any suitable number of transmitters 210 and receivers 212. The transmitter 210 and the receiver 212 may be any suitable type of transmitters and receivers. In one embodiment, the transmitter 210 and the receiver 212 may be part of a transceiver.

[0052] Figure 3 depicts one embodiment of an apparatus 300 that may be used for configuration based on two tracking reference signals. The apparatus 300 includes one embodiment of the network unit 104. Furthermore, the network unit 104 may include a processor 302, a memory 304, an input device 306, a display 308, a transmitter 310, and a receiver 312. As may be appreciated, the processor 302, the memory 304, the input device 306, the display 308, the transmitter 310, and the receiver 312 may be substantially similar to the processor 202, the memory 204, the input device 206, the display 208, the transmitter 210, and the receiver 212 of the remote unit 102, respectively.

[0053] In certain embodiments, the transmitter 310: transmits downlink control information that schedules a downlink transmission, wherein: the downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and transmits at least two tracking reference signals from the at least two network nodes. In various embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0054] In certain embodiments, high speed rail may be used. High speed rail is expanding in various parts of the world and the number of passengers on the high speed rails with smart devices like laptops and mobile phones is increasing. Certain technologies like may support data ranges from tens of kbps to tens of Mbps, but this may not be enough to handle a demand for high- data-rates and increased reliability and/or latency for on-board broadband services. In some embodiments, there may be enhancements to support high speed train (“HST”) configurations and/or single frequency network (“SFN”) configurations.

[0055] In various embodiments, such as on SFN configurations (e.g., all cells operate at the same frequency), multiple remote radio heads may be located along a railway and connected to a central unit (e.g., via fiber). The remote radio heads may share the same cell ID. If the transmission from transmit-receive points (“TRPs”) within a cell are synchronized, SFN deployment may enlarge a cell coverage, reduce a frequency of handovers, and achieve transmission diversity and/or power gain. One embodiment of a 4 GHz system is shown in Figure 4. In such an embodiment, based on a 6 dB pathloss difference between any two TRPs, a train may take advantage of two simultaneous TRP transmissions for sessions of at least 4 seconds long, assuming a train speed of 500 km/hr.

[0056] Figure 4 is a schematic block diagram illustrating one embodiment of a system 400 having a high speed train. The system includes a baseband unit (“BBU”) 402, a first remote radio head (“RRH”) 404 (RRH1), a second RRH 406 (RRH2), a third RRH 408 (RRH3), and a fourth RRH 410 (RRH4). Each of RRH1 404, RRH2 406, RRH3 408, and RRH4 410 may operate as a TRP for communicating with devices on a high speed vehicle 412 (e.g., HST).

[0057] In certain embodiments, for SFN transmission, a physical downlink shared channel (“PDSCH”) transmission is repeated from two TRPs using a single scheduling downlink control information (“DQ”) indicating a single demodulation reference signal (“DMRS”) port and a single transmission configuration indicator (“TCI”) state. As may be appreciated in relation to Figure 4, the doppler shift for the transmission a first TRP (TRP1) (e.g., RRH1 404) is different than the doppler shift from a second TRP (TRP2) (e.g., RRH2 406). If a receiver uses long-term channel statistics associated with an indicated TCI state to estimate an aggregate channel, this may lead to estimation errors and performance degradation.

[0058] In some embodiments, a single DCI multi -TRP transmission may be used. The DCI may indicate DMRS ports from different code division multiplexing (“CDM”) groups along with a TCI codepoint indicating two TCI states. Some layers of a transmitted transport block (“TB”) may be sent from TRP1 and some layers from TRP2. This may cause interlayer interference and may not achieve a power gain (e.g., hence no increase in cell coverage). In such embodiments, due to varying proximity of two TRPs to a user equipment (“UE”), a signal to noise ratio (“SNR”) gap between signals from the two TRPs may lead to constraining a modulation and coding scheme (“MCS”) level (e.g., indicated via a channel quality indicator (“CQI”)) to the worse of both transmissions.

[0059] Described herein are various embodiments that enable a UE to receive data from the same ports from multiple TRPs to achieve a power gain while estimating independently a channel from each TRP to improve performance.

[0060] In various embodiments, a UE is configured with two tracking reference signals (“TRSs”) (e.g., two TRS resource sets or two NZP-CSI-RS-ResourceSet configured with higher layer parameter trs-Info) thereby establishing fine time and/or frequency synchronization with respect to TRP1 and TRP2 respectively (e.g., see Figure 5). The two TRSs (first TRS and second TRS) may be sent in a TRS-specific manner (e.g., one TRS sent from each TRP), or the first TRP sends both TRSs whereas the second TRP sends the first TRS only. The UE receives a downlink scheduling DCI indicating a physical downlink shared channel (“PDSCH”) and associated DMRS ports (e.g., one set of DMRS ports, the number of DMRS ports may be equal to the number of PDSCH layers of the transmission, double the number of PDSCH layers of the transmission), and a TCI codepoint referring to two TCI states, a first TCI state and a second TCI state. In one example, the PDSCH transmission occasion is associated with the first TCI state and the second TCI state. The first TCI state may include the first TRS as a source reference signal (“RS”) to provide a reference for determining quasi-co-location (“QCL”) for a target transmission (e.g., PDSCH transmission occasion, first set of DMRS ports, DMRS ports on a first set of time and/or frequency resource elements). The QCL properties may be derived from the first TRS. The second TCI state may include the second TRS as a source RS to provide a reference for determining QCL for a target transmission (e.g., PDSCH transmission occasion, second set of DMRS ports, DMRS ports on a second set of time and/or frequency resource elements). The QCL properties may be derived from the first TRS.

[0061] In certain embodiments, DMRS ports are from one CDM group.

[0062] In some embodiments, DMRS ports are transmitted from two TRPs in a time division multiplexing (“TDM”) fashion (e.g., the DMRS symbols are transmitted in the same fashion as that if a UE is configured by a higher layer parameter RepSchemeEnabler set to ‘TDMSchemeA’). In one example, the DMRS ports on a set of time and/or frequency resource elements of a first set of symbols are transmitted from a first TRP (e.g., DMRS transmission on the DMRS ports is associated and/or corresponds to the first TCI state), and the same DMRS ports on a set of time and/or frequency resource elements of a second set of symbols are transmitted from a second TRP (e.g., DMRS transmission on the DMRS ports is associated and/or corresponds to the second TCI state).

[0063] In various embodiments, DMRS ports are sent from two TRPs in a frequency division multiplexing (“FDM”) fashion (e.g., the DMRS symbols are transmitted in the same fashion as that if a UE is configured by a higher layer parameter RepSchemeEnabler set to ‘FDMSchemeA’). In one example, the DMRS ports on a first set of time and/or frequency resource elements of a first set of symbols are transmitted from a first TRP (e.g., DMRS transmission corresponding to the DMRS ports is associated to the first TCI state), and the same DMRS ports on a second set of time and/or frequency resource elements of the first set of symbols are transmitted from a second TRP (e.g., DMRS transmission corresponding to the DMRS ports is associated to the second TCI state).

[0064] In certain embodiments, two TCI states may indicate two TRSs as their source RSs (e.g., a first TRS as source RS for a first TCI state, and a second TRS as source RS for a second TCI state). In one example, a TCI state may indicate QCL information with a source reference signal (e.g., channel state information RS (“CSI-RS”)) which may in turn be QCL with a TRS. For the reception of PDSCH DMRS, QCL typeA properties (e.g., Doppler shift, Doppler spread, average delay, delay spread) may be inferred from a periodic TRS. In some examples, other QCL relationships between PDSCH DMRS and periodic TRS (e.g., QCL typeB, QCL typeC, a new QCL type such as TypeE or TypeF) are not precluded. [0065] Figure 5 is a schematic block diagram illustrating one embodiment of a system 500 for configured with two TRSs for TRP1 and TRP2 synchronization. Specifically, the system 500 includes a first RRH 502 (RRH1 or TRP1), a second RRH 504 (RRH2 or TRP2), and a HST 506. The first RRH 502 transmits a first TRS 508 (Hi with codeword x) to the HST 506 (e.g., UEs on the HST 506), and the second RRH 504 transmits a second TRS 510 (H2 with codeword x) to the HST 506 (e.g., UEs on the HST 506). In some embodiments, the first RRH 502 may also transmit the second TRS 510.

[0066] If a number of PDSCH DMRS ports is equal to a number of PDSCH layers, the PDSCH DMRS is configured with a single symbol and with one additional symbol (e.g., type 1 or type 2, Mapping type A or B). For example, there may be two DMRS symbols in total within a slot (e.g., see Figure 6 as an example). With two periodic TRSs configured, a UE (e.g., on the HST 506) uses the first (e.g., first pair) DMRS symbols to estimate the channel from TRP1, denoted byHl, assuming it is QCL’ed with the first TRS 508. The UE uses the second (e.g., second pair) DMRS symbols to estimate the channel from TRP2, denoted as H2, assuming it is QCLed with the second TRS. In certain embodiments, a network transmits the codeword x over the channel Hl + H2 (e.g., the UE receives (Hl + H2)*x while estimating Hl and H2 independently).

[0067] Figure 6 is a schematic block diagram illustrating one embodiment of a DMRS pattern 600 for a front loaded DMRS with a single symbol and one additional symbol. DMRS symbols 602 are used to estimate Hi, and DMRS symbols 604 are used to estimate H2.

[0068] In certain embodiments, a PDSCH DMRS is configured with a single symbol and with three additional symbols (e.g., type 1 or type 2) (e.g., four DMRS symbols in total within a slot (e.g., see Figure 7 as an example)). With two periodic TRSs configured, the UE uses the first and third DMRS symbols to estimate the channel from TRP1, denoted by Hl, assuming it is QCL’ed with the first TRS. The UE uses the second and fourth DMRS symbols to estimate the channel from TRP2, denoted as H2, assuming it is QCLed with the second TRS. In this scenario, the network transmits the codeword x over the channel Hl + H2 (e.g., the UE receives (Hl + H2)*x while estimating Hl and H2 independently).

[0069] Figure 7 is a schematic block diagram illustrating one embodiment of a DMRS pattern 700 for a front loaded DMRS with a single symbol and three additional symbols. DMRS symbols 702 are used to estimate Hi, and DMRS symbols 704 are used to estimate H2.

[0070] In some embodiments, a PDSCH DMRS is configured with a single symbol and with one additional symbol (e.g., type 1 or type 2) (e.g., two DMRS symbols in total within a slot (e.g., see Figure 8 as an example)). The UE receives a downlink scheduling DCI, indicating DMRS ports from one CDM group, and a TCI state codepoint. The two TCI states have the two TRSs as their source RSs. With two periodic TRSs configured, the UE uses half of the REs of the first DMRS symbols and half of the REs of the second DMRS symbols (e.g., see Figure 8) to estimate the channel from TRP1, denoted by Hl, assuming it is QCL’ed with the first TRS. This may improve performance for high doppler spreads with small coherence time especially for low subcarrier spacing. The UE uses the second half of the REs of the first DMRS symbols and the second half of the REs of the second DMRSs to estimate the channel from TRP2, denoted by H2, assuming it is QCL’ed with the second TRS. In this scenario, the network transmits the codeword x over the channel Hl + H2 (e.g., the UE receives (Hl + H2)*x while estimating Hl and H2 independently).

[0071] Figure 8 is a schematic block diagram 800 illustrating one embodiment of DMRS REs from different DMRS symbols for channel estimation (e.g., to combat Doppler spread). DMRS symbols 802 are used to estimate Hi, and DMRS symbols 804 are used to estimate H2.

[0072] In various embodiments, the UE is configured with a higher layer parameter (e.g., RepSchemeEnabler = “TDMSchemeA”) where the UE is enabled, semi-statically, to support single DCI two PDSCH repetition or two physical random shared channel (“PRSCH”) transmission occasions (e.g., which have non-overlapping time domain resource allocation such as two mini-slot based repetitions of the PDSCH within a slot). The UE is configured with two TRSs, establishing fine time and/or frequency synchronization with respect to TRP1 and TRP2. The UE receives a downlink scheduling DCI, and a two TCI state codepoint with each TCI state associated to a PDSCH transmission occasion, with one redundancy version. The two TCI states have the two TRSs as their source RSs. The UE uses the DMRS symbol in PDSCH 1 and/or PDSCH transmission occasion 1 (e.g., see Figure 9) to estimate the channel from TRP1, denoted by Hl, assuming it is QCL’ed with the first TRS (e.g., associated with first TCI state). The UE the DMRS symbol in PDSCH 2 and/or PDSCH transmission occasion 2 to estimate the channel from TRP2, denoted by H2, assuming it is QCL’ed with the second TRS (e.g., associated with second TCI state). In this scenario, the network transmits Hl*x on PDSCH 1 and H2*x on PDSCH 2. The UE then decodes (Hl + H2)*x while estimating Hl and H2 independently.

[0073] In certain embodiments, DCI may indicate more than two PDSCH repetitions. The PDSCH repetitions may span more than one slot. Moreover, a PDSCH repetition may be confined to within a slot or multiple slots and may span across a slot boundary.

[0074] Figure 9 is a schematic block diagram 900 illustrating one embodiment of a single DCI scheduling for two minislots (e.g., with PDSCHs carrying the same TB for power gain). A first PDSCH 902 (PDSCH1) is transmitted from RRH1, and a second PDSCH 904 (PDSCH2) is transmited from RRH2. DMRS symbols 906 are used to estimate Hi, and DMRS symbols 908 are used to estimate H2.

[0075] In some embodiments, a UE is configured by a higher layer parameter (e.g., PDSCH-config) that indicates at least one entry in pdsch-TimeDomainAllocationList containing repetitionNumber-R16in PDSCH-TimeDomainResourceAllocation. The UE receives a downlink scheduling DCI with two TCI states in a codepoint of the DCI field 'Transmission Configuration Indication' together with the DCI field “Time domain resource assignment’ indicating an entry in pdsch-TimeDomainAllocationList which contain repetitionNumber-R16 in PDSCH- TimeDomainResourceAllocation and DM-RS ports within one CDM group in the DCI field “Antenna Port(s)”. Candidate values of repetitionNumber-R16 = {2, 3, 4, 5, 6, 7, 8, 16} . The downlink scheduling DCI is a single DCI indicating multi PDSCH repetitions across slots (e.g., see Figure 10). The downlink scheduling DCI indicates a two TCI state codepoint (e.g., with each TCI state associated to at least one PDSCH transmission occasion of the multiple PDSCH transmission occasions in the repetitionNumber-rl6 consecutive slots) and a single RV. The two TCI states have the two TRSs as their source RSs. Considering repetitionNumber-rl6 is set to “2”, the UE uses the DMRS symbol in PDSCH 1 and/or PDSCH transmission occasion 1 (e.g., see Figure 10) to estimate the channel from TRP1, denoted by Hl, assuming it is QCL’ed with the first TRS (e.g., associated with a first TCI state). The UE the DMRS symbol in PDSCH 2 and/or PDSCH transmission occasion 2 to estimate the channel from TRP2, denoted by H2, assuming it is QCL’ed with the second TRS (e.g., associated with a second TCI state). In this scenario, the network transmits Hl*x on PDSCH 1 and H2*x on PDSCH 2. The UE then decodes (Hl + H2)*x while estimating Hl and H2 independently.

[0076] Figure 10 is a schematic block diagram 1000 illustrating one embodiment of a single DCI scheduling for two PDSCHs (e.g., carrying the same TB for power gain). A first PDSCH 1002 (PDSCH1) is transmited from RRH1, and a second PDSCH 1004 (PDSCH2) is transmited from RRH2. DMRS symbols 1006 are used to estimate Hi, and DMRS symbols 1008 are used to estimate H2.

[0077] In various embodiments, transmissions from TRP1 and TRP2 may be precoded independently (e.g., the precoders may be different). In some examples, the DMRS is precoded using the same precoder as that used for a PDSCH transmission. In various examples, the precoder is determined based on channel state information (“CSI”) feedback from the UE. The CSI feedback may include CSI for TRP1 and/or CSI for TRP2.

[0078] In some embodiments, for demodulation reference signal (“DM-RS”) associated with a PDSCH, a channel over which a PDSCH symbol on one antenna port is conveyed may be inferred from a channel over which a DM-RS symbol on the same antenna port is conveyed only if the two symbols are within the same resource as the scheduled PDSCH, in the same PRG, and in the same mini-slot.

[0079] In various embodiments, for DM-RS associated with a PDSCH, a channel over which a PDSCH symbol on one antenna port is conveyed may be inferred from the channel over which a DM-RS symbol on the same antenna port is conveyed only if the two symbols are within the same resource as the scheduled PDSCH, in the same physical resource group (“PRG”), and if one or more higher layer parameters related to users with high speed (e.g., highSpeedEnhancedDemodulationFlag, highSpeedFlag, orhighSpeedEnhDemodFlag-rl7) are not configured.

[0080] In some embodiments, for DM-RS associated with a PDSCH, a channel over which a PDSCH symbol on one antenna port is conveyed may be inferred from a channel over which a DM-RS symbol on the same antenna port is conveyed only if the two symbols are within the same resource as the scheduled PDSCH, in the same PRG, and if the UE is configured with one or more higher layer parameters related to grouping the PDSCH DMRS symbols within one or more DMRS ports (e.g., DMRS-SymbolGroups set to ‘2’, DMRS-Groups, or DMRSforHighSpeed).

[0081] In various embodiments, for DM-RS associated with a PDSCH, a channel over which a PDSCH symbol on one antenna port is conveyed may be inferred from a channel over which a DM-RS symbol on the same antenna port is conveyed only if the two symbols are within the same resource as the scheduled PDSCH, in the same PRG, and associated with the same TCI state. In one example, the two symbols are in the same slot or mini-slot. In another example, the scheduled PDSCH is the scheduled PDSCH transmission occasion. In some examples, at least one TCI state associated with, assigned to, and/or corresponding to the PDSCH symbol and the DMRS symbol is the same. In various examples, the PDSCH symbol is assigned a first TCI state and a second TCI state, and the DMRS symbol associated with the PDSCH is assigned only a first TCI state. In certain examples, the channel inference may be a partial inference (e.g., channel Hl or channel H2 over DM-RS symbol, and channel H1+H2 over PDSCH symbol). In some examples, “associated with the same TCI state” may be replaced by “associated with at least one same TCI state” and may be used interchangeably.

[0082] In some embodiments, the terms antenna, panel, and antenna panel are used interchangeably. An antenna panel may be hardware that is used for transmitting and/or receiving radio signals at frequencies lower than 6 GHz (e.g., frequency range 1 (“FR1”)), or higher than 6 GHz (e.g., frequency range 2 (“FR2”) or millimeter wave (“mmWave”)). In certain embodiments, an antenna panel may include an array of antenna elements. Each antenna element may be connected to hardware, such as a phase shifter, that enables a control module to apply spatial parameters for transmission and/or reception of signals. The resulting radiation pattern may be called a beam, which may or may not be unimodal and may allow the device to amplify signals that are transmitted or received from spatial directions.

[0083] In various embodiments, an antenna panel may or may not be virtualized as an antenna port. An antenna panel may be connected to a baseband processing module through a radio frequency (“RF”) chain for each transmission (e.g., egress) and reception (e.g., ingress) direction. A capability of a device in terms of a number of antenna panels, their duplexing capabilities, their beamforming capabilities, and so forth, may or may not be transparent to other devices. In some embodiments, capability information may be communicated via signaling or capability information may be provided to devices without a need for signaling. If information is available to other devices the information may be used for signaling or local decision making.

[0084] In some embodiments, a UE antenna panel may be a physical or logical antenna array including a set of antenna elements or antenna ports that share a common or a significant portion of a radio frequency (“RF”) chain (e.g., in-phase and/or quadrature (“I/Q”) modulator, analog to digital (“A/D”) converter, local oscillator, phase shift network). The UE antenna panel or UE panel may be a logical entity with physical UE antennas mapped to the logical entity. The mapping of physical UE antennas to the logical entity may be up to UE implementation. Communicating (e.g., receiving or transmitting) on at least a subset of antenna elements or antenna ports active for radiating energy (e.g., active elements) of an antenna panel may require biasing or powering on of an RF chain which results in current drain or power consumption in a UE associated with the antenna panel (e.g., including power amplifier and/or low noise amplifier (“LNA”) power consumption associated with the antenna elements or antenna ports). The phrase “active for radiating energy,” as used herein, is not meant to be limited to a transmit function but also encompasses a receive function. Accordingly, an antenna element that is active for radiating energy may be coupled to a transmitter to transmit radio frequency energy or to a receiver to receive radio frequency energy, either simultaneously or sequentially, or may be coupled to a transceiver in general, for performing its intended functionality. Communicating on the active elements of an antenna panel enables generation of radiation patterns or beams.

[0085] In certain embodiments, depending on a UE’s own implementation, a “UE panel” may have at least one of the following functionalities as an operational role of unit of antenna group to control its transmit (“TX”) beam independently, unit of antenna group to control its transmission power independently, and/pr unit of antenna group to control its transmission timing independently. The “UE panel” may be transparent to a gNB. For certain conditions, a gNB or network may assume that a mapping between a UE’s physical antennas to the logical entity “UE panel” may not be changed. For example, a condition may include until the next update or report from UE or include a duration of time over which the gNB assumes there will be no change to mapping. A UE may report its UE capability with respect to the “UE panel” to the gNB or network. The UE capability may include at least the number of “UE panels.” In one embodiment, a UE may support UL transmission from one beam within a panel. With multiple panels, more than one beam (e.g., one beam per panel) may be used for UL transmission. In another embodiment, more than one beam per panel may be supported and/or used for UL transmission.

[0086] In some embodiments, an antenna port may be defined such that a channel over which a symbol on the antenna port is conveyed may be inferred from the channel over which another symbol on the same antenna port is conveyed.

[0087] In certain embodiments, two antenna ports are said to be quasi co-located (“QCL”) if large-scale properties of a channel over which a symbol on one antenna port is conveyed may be inferred from the channel over which a symbol on another antenna port is conveyed. Large- scale properties may include one or more of delay spread, Doppler spread, Doppler shift, average gain, average delay, and/or spatial receive (“RX”) parameters. Two antenna ports may be quasi co-located with respect to a subset of the large-scale properties and different subset of large-scale properties may be indicated by a QCL Type. For example, a qcl-Type may take one of the following values: 1) 'QCL-TypeA': {Doppler shift, Doppler spread, average delay, delay spread}; 2) 'QCL-TypeB': {Doppler shift, Doppler spread}; 3) 'QCL-TypeC: {Doppler shift, average delay}; and 4) 'QCL-TypeD': {Spatial Rx parameter} .

[0088] In various embodiments, spatial RX parameters may include one or more of: angle of arrival (“AoA”), dominant AoA, average AoA, angular spread, power angular spectrum (“PAS”) of AoA, average angle of departure (“AoD”), PAS of AoD, transmit and/or receive channel correlation, transmit and/or receive beamforming, and/or spatial channel correlation.

[0089] In certain embodiments, QCL-TypeA, QCL-TypeB, and QCL-TypeC may be applicable for all carrier frequencies, but QCL-TypeD may be applicable only in higher carrier frequencies (e.g., mmWave, FR2, and beyond), where the UE may not be able to perform omnidirectional transmission (e.g., the UE would need to form beams for directional transmission). For a QCL-TypeD between two reference signals A and B, the reference signal A is considered to be spatially co-located with reference signal B and the UE may assume that the reference signals A and B can be received with the same spatial filter (e.g., with the same RX beamforming weights).

[0090] In some embodiments, an “antenna port” may be a logical port that may correspond to a beam (e.g., resulting from beamforming) or may correspond to a physical antenna on a device. In certain embodiments, a physical antenna may map directly to a single antenna port in which an antenna port corresponds to an actual physical antenna. In various embodiments, a set of physical antennas, a subset of physical antennas, an antenna set, an antenna array, or an antenna sub-array may be mapped to one or more antenna ports after applying complex weights and/or a cyclic delay to the signal on each physical antenna. The physical antenna set may have antennas from a single module or panel or from multiple modules or panels. The weights may be fixed as in an antenna virtualization scheme, such as cyclic delay diversity (“CDD”). A procedure used to derive antenna ports from physical antennas may be specific to a device implementation and transparent to other devices.

[0091] In certain embodiments, a TCI-state associated with a target transmission may indicate parameters for configuring a quasi-co-location relationship between the target transmission (e.g., target RS of DM-RS ports of the target transmission during a transmission occasion) and a source reference signal (e.g., synchronization signal block (“SSB”), CSI-RS, and/or sounding reference signal (“SRS”)) with respect to quasi co-location type parameters indicated in a corresponding TCI state. The TCI describes which reference signals are used as a QCL source, and what QCL properties may be derived from each reference signal. A device may receive a configuration of a plurality of transmission configuration indicator states for a serving cell for transmissions on the serving cell. In some embodiments, a TCI state includes at least one source RS to provide a reference (e.g., UE assumption) for determining QCL and/or a spatial filter.

[0092] In some embodiments, spatial relation information associated with a target transmission may indicate a spatial setting between a target transmission and a reference RS (e.g., SSB, CSI-RS, and/or SRS). For example, a UE may transmit a target transmission with the same spatial domain filter used for receiving a reference RS (e.g., DL RS such as SSB and/or CSI-RS). In another example, a UE may transmit a target transmission with the same spatial domain transmission filter used for the transmission of a RS (e.g., UL RS such as SRS). A UE may receive a configuration of multiple spatial relation information configurations for a serving cell for transmissions on a serving cell.

[0093] Figure 11 is a flow chart diagram illustrating one embodiment of a method 1100 for configuration based on two tracking reference signals. In some embodiments, the method 1100 is performed by an apparatus, such as the remote unit 102. In certain embodiments, the method 1100 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0094] In various embodiments, the method 1100 includes receiving 1102, at a user equipment, downlink control information that schedules a downlink transmission. The downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission. In some embodiments, the method 1100 includes receiving 1104 at least two tracking reference signals from the at least two network nodes. In certain embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0095] In certain embodiments, the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes. In some embodiments, the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes. In various embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same.

[0096] In one embodiment, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots. In certain embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A. In some embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots.

[0097] In various embodiments, the method 1100 further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; are in a same precoding resource block group; and are in a same mini-slot. In one embodiment, the method 1100 further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if at least one higher layer parameter related to a high-speed configuration is not configured.

[0098] In certain embodiments, the method 1100 further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if a user equipment is configured with at least one higher layer parameter related to grouping physical downlink shared channel symbols with demodulation reference signal symbols within the at least one demodulation reference signal port. In some embodiments, the method 1100 further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and physical downlink shared channel resources corresponding to the physical downlink shared channel symbol and the demodulation reference signal are associated with a same transmission configuration indication state.

[0099] Figure 12 is a flow chart diagram illustrating another embodiment of a method 1200 for configuration based on two tracking reference signals. In some embodiments, the method 1200 is performed by an apparatus, such as the network unit 104. In certain embodiments, the method 1200 may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0100] In various embodiments, the method 1200 includes transmitting 1202 downlink control information that schedules a downlink transmission. The downlink control information includes a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information includes information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission. In some embodiments, the method 1200 includes transmitting 1204 at least two tracking reference signals from the at least two network nodes. In certain embodiments, a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0101] In certain embodiments, the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes. In some embodiments, the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes. In various embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same.

[0102] In one embodiment, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots. In certain embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A. In some embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots.

[0103] In one embodiment, a method at a user equipment comprises: receiving downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and receiving at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0104] In certain embodiments, the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes.

[0105] In some embodiments, the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes.

[0106] In various embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same.

[0107] In one embodiment, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots.

[0108] In certain embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A.

[0109] In some embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots.

[0110] In various embodiments, the method further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; are in a same precoding resource block group; and are in a same mini-slot.

[0111] In one embodiment, the method further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if at least one higher layer parameter related to a high-speed configuration is not configured.

[0112] In certain embodiments, the method further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if a user equipment is configured with at least one higher layer parameter related to grouping physical downlink shared channel symbols with demodulation reference signal symbols within the at least one demodulation reference signal port.

[0113] In some embodiments, the method further comprises inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and physical downlink shared channel resources corresponding to the physical downlink shared channel symbol and the demodulation reference signal are associated with a same transmission configuration indication state.

[0114] In one embodiment, an apparatus comprises a user equipment. The apparatus further comprises: a receiver that: receives downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and receives at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0115] In certain embodiments, the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes.

[0116] In some embodiments, the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes.

[0117] In various embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same.

[0118] In one embodiment, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots.

[0119] In certain embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A.

[0120] In some embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots.

[0121] In various embodiments, the apparatus further comprises a processor that infers a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; are in a same precoding resource block group; and are in a same mini-slot.

[0122] In one embodiment, the apparatus further comprises a processor that infers a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if at least one higher layer parameter related to a highspeed configuration is not configured.

[0123] In certain embodiments, the apparatus further comprises a processor that infers a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if a user equipment is configured with at least one higher layer parameter related to grouping physical downlink shared channel symbols with demodulation reference signal symbols within the at least one demodulation reference signal port.

[0124] In some embodiments, the apparatus further comprises a processor that infers a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and physical downlink shared channel resources corresponding to the physical downlink shared channel symbol and the demodulation reference signal are associated with a same transmission configuration indication state.

[0125] In one embodiment, a method of a network unit comprises: transmitting downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and transmitting at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0126] In certain embodiments, the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes.

[0127] In some embodiments, the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes. [0128] In various embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same.

[0129] In one embodiment, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots.

[0130] In certain embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A.

[0131] In some embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots.

[0132] In one embodiment, an apparatus comprises a network unit. The apparatus further comprises: a transmitter that: transmits downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and transmits at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

[0133] In certain embodiments, the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes.

[0134] In some embodiments, the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes. [0135] In various embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same.

[0136] In one embodiment, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots.

[0137] In certain embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A.

[0138] In some embodiments, the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots.

[0139] Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A method at a user equipment, the method comprising: receiving downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and receiving at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port.

2. The method of claim 1, wherein the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes.

3. The method of claim 1, wherein the first tracking reference signal is sent from one network node, and the second tracking reference signal is sent from two network nodes.

32 The method of claim 1, wherein the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are the same. The method of claim 1, wherein the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots. The method of claim 1, wherein the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using frequency division multiplexing based on frequency division multiplexing scheme A. The method of claim 1, wherein the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing across different mini-slots in a slot, and the slot comprises a plurality of mini-slots. The method of claim 1, further comprising inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; are in a same precoding resource block group; and are in a same mini-slot. The method of claim 1, further comprising inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if at least one higher layer parameter related to a high-speed configuration is not configured.

33 The method of claim 1, further comprising inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and if a user equipment is configured with at least one higher layer parameter related to grouping physical downlink shared channel symbols with demodulation reference signal symbols within the at least one demodulation reference signal port. The method of claim 1, further comprising inferring a channel over which a physical downlink shared channel symbol on one antenna port is conveyed from a channel over which a demodulation reference signal symbol on the one antenna port is conveyed if the physical downlink shared channel symbol and the demodulation reference signal symbol: are within a same resource as a scheduled physical downlink shared channel; and are in a same precoding resource block group; and physical downlink shared channel resources corresponding to the physical downlink shared channel symbol and the demodulation reference signal are associated with a same transmission configuration indication state. An apparatus comprising a user equipment, the apparatus further comprising: a receiver that: receives downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and receives at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port. An apparatus comprising a network unit, the apparatus further comprising: a transmitter that: transmits downlink control information that schedules a downlink transmission, wherein: the downlink control information comprises a transmission configuration indication codepoint; the transmission configuration indication codepoint corresponds to two transmission configuration indication states associated with at least two network nodes; the downlink control information comprises information corresponding to at least one demodulation reference signal port; and the at least one demodulation reference signal port corresponds to at least one layer of a physical downlink shared channel transmission; and transmits at least two tracking reference signals from the at least two network nodes; wherein: a first transmission configuration indication state of the two transmission configuration indication states corresponds to a first tracking reference signal of the at least two tracking reference signals; the first tracking reference signal is a first source reference signal of a first symbol subset of the at least one demodulation reference signal port; a second transmission configuration indication state of the two transmission configuration indication states corresponds to a second tracking reference signal of the at least two tracking reference signals; and the second tracking reference signal is a second source reference signal of a second symbol subset of the at least one demodulation reference signal port. The apparatus of claim 13, wherein the first tracking reference signal is sent from a first network node of the at least two network nodes, and the second tracking reference signal is transmitted from a second network node of the at least network nodes. The apparatus of claim 13, wherein the first symbol subset and the second symbol subset of the at least one demodulation reference signal port are transmitted using time division multiplexing based on time division multiplexing scheme A across slots.

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