Apparatus, method and apparatus for coherent joint transmission

Abstract

The embodiment of the invention discloses equipment, a method and a device for coherent joint transmission. A terminal device may receive a QCL source configuration from a network device. The QCL source configuration may indicate at least two transmission configuration indication (TCI) states that indicate a reference signal from an active QCL source that is used to track coherent joint transmission (CJT) of a reference signal (TRS). The terminal device may perform QCL attribute estimation on the received TRS based on the QCL source configuration.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of communications, and in particular, to devices, methods, apparatuses, and computer-readable storage media for coherent joint transmission. Background Art

[0002] In a New Radio (NR) system, cooperative transmission schemes can be used for multi-Transmit Receive Point (TRP) operations. The cooperative transmission schemes can be divided into two types: Coherent Joint Transmission (CJT) and Non-Coherent Joint Transmission (NCJT), depending on the mapping relationship between the transmitted data layer and multiple TRPs.

[0003] In the Physical Downlink Shared Channel (PDSCH) transmission from multiple TRPs in CJT, the channel characteristics at the receiver of the terminal device can vary according to the precoder used in the joint precoding. In addition, different numbers of TRPs can be involved at different PDSCH transmission instances. Therefore, the terminal device needs to estimate the channel characteristics for PDSCH reception based on a set of TRP-specific Tracking Reference Signals (TRS), which may pose some challenges to the current system. Summary of the Invention

[0004] Generally, example embodiments of the present disclosure provide devices, methods, apparatuses, and computer-readable storage media for coherent joint transmission.

[0005] In a first aspect, a terminal device is provided. The terminal device may include: one or more transceivers; and one or more processors communicatively coupled to the one or more transceivers, and the one or more processors are configured to cause the terminal device to: receive a Quasi-Co-Location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two Transmission Configuration Indicator (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source for Coherent Joint Transmission (CJT) of a Tracking Reference Signal (TRS); and perform QCL attribute estimation on the received TRS based on the QCL source configuration.

[0006] In a second aspect, a network device is provided. The network device may include: one or more transceivers; and one or more processors communicatively coupled to the one or more transceivers, and the one or more processors are configured to cause the network device to: receive the result of measurements on a Channel State Information Reference Signal (CSI-RS) set from a terminal device; and send a Quasi-Co-Location (QCL) source configuration to the terminal device, where the QCL source configuration indicates at least two Transmission Configuration Indicator (TCI) states based on the result of measurements on the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source for Coherent Joint Transmission (CJT) of a Tracking Reference Signal (TRS).

[0007] In a third aspect, a method implemented at a terminal device is provided. The method may include: receiving a quasi-co-location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of a tracking reference signal (TRS); and performing QCL attribute estimation on the received TRS based on the QCL source configuration.

[0008] In a fourth aspect, a method implemented at a network device is provided. The method may include: receiving, from a terminal device, a result of measurement of a channel state information reference signal (CSI-RS) set; and sending a quasi-co-location (QCL) source configuration to the terminal device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the result of measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used to track coherent joint transmission (CJT) of a reference signal (TRS).

[0009] In a fifth aspect, an apparatus for a terminal device is provided. The apparatus may include: means for receiving a quasi-co-location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of a tracking reference signal (TRS); and means for performing QCL attribute estimation on the received TRS based on the QCL source configuration.

[0010] In a sixth aspect, an apparatus for a network device is provided. The apparatus may include: means for receiving, from a terminal device, a result of measurement of a channel state information reference signal (CSI-RS) set; and means for sending a quasi-co-location (QCL) source configuration to the terminal device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the result of measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used to track coherent joint transmission (CJT) of a reference signal (TRS).

[0011] In a seventh aspect, a terminal device is provided. The terminal device may include: at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the terminal device to: receive a quasi co-location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of a tracking reference signal (TRS); and perform QCL attribute estimation on the received TRS based on the QCL source configuration.

[0012] In an eighth aspect, a network device is provided. The network device may include: at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the terminal device to: receive, from the terminal device, a result of measurement of a channel state information reference signal (CSI-RS) set; and send a quasi co-location (QCL) source configuration to the terminal device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the result of measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of a tracking reference signal (TRS).

[0013] In a ninth aspect, a non-transitory computer-readable medium is provided, the non-transitory computer-readable medium including program instructions for causing a device to at least execute the method according to the third aspect or the fourth aspect.

[0014] In a tenth aspect, a computer program is provided, the computer program including instructions that, when executed by a device, cause the device to at least: receive a quasi co-location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of a tracking reference signal (TRS); and perform QCL attribute estimation on the received TRS based on the QCL source configuration.

[0015] In an eleventh aspect, a computer program is provided, the computer program comprising instructions which, when executed by a device, cause the device to at least: receive, from a terminal device, a result of measurement of a channel state information reference signal (CSI-RS) set; and send, to the terminal device, a quasi co-location (QCL) source configuration, wherein the QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the result of measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, the reference signals being used for coherent joint transmission (CJT) of a tracking reference signal (TRS).

[0016] In a twelfth aspect, a terminal device is provided. The terminal device comprises: receiving circuitry configured to receive a quasi co-location (QCL) source configuration from a network device, wherein the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, the reference signals being used for coherent joint transmission (CJT) of a tracking reference signal (TRS); and estimating circuitry configured to perform QCL attribute estimation on a received TRS based on the QCL source configuration.

[0017] In a thirteenth aspect, a network device is provided. The network device comprises: receiving circuitry configured to receive, from a terminal device, a result of measurement of a channel state information reference signal (CSI-RS) set; and sending circuitry configured to send, to the terminal device, a quasi co-location (QCL) source configuration, wherein the QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the result of measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, the result of the reference signals being used for coherent joint transmission (CJT) of a tracking reference signal (TRS).

[0018] It should be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become readily apparent through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Some example embodiments will now be described with reference to the drawings, in which:

[0020] Figure 1 An example communication network environment in which example embodiments of the present disclosure may be implemented is illustrated;

[0021] Figure 2 An example signaling procedure for coherent joint transmission according to some embodiments of the present disclosure is illustrated;

[0022] Figures 3A - 3CIllustrates an example scenario in CJT using multiple TRPs according to an embodiment of the present disclosure;

[0023] Figure 4 Illustrates an example schematic diagram 400 of receiving CJT TRS and DMRS according to an embodiment of the present disclosure;

[0024] Figure 5 Shows a flowchart of an example method 500 implemented at a terminal device according to some embodiments of the present disclosure;

[0025] Figure 6 Shows a flowchart of an example method 600 implemented at a network device according to some embodiments of the present disclosure;

[0026] Figure 7 Is a simplified block diagram of a device 700 suitable for implementing embodiments of the present disclosure; and

[0027] Figure 8 Shows an example of a computer-readable medium 800 in the form of a CD or DVD.

[0028] Throughout the drawings, the same or similar reference numerals denote the same or similar elements. Detailed Description

[0029] Now, the principles of the present disclosure will be described with reference to some example embodiments. It should be understood that these embodiments are described for illustrative purposes only and help those skilled in the art understand and implement the present disclosure, and do not represent any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various other ways than those described below.

[0030] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0031] In the present disclosure, references to "one embodiment", "embodiment", "example embodiment", etc. indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment must include the specific feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a specific feature, structure, or characteristic is described in connection with an embodiment, those skilled in the art will recognize that, whether or not explicitly described, combining such features, structures, or characteristics with other embodiments is within the knowledge of those skilled in the art.

[0032] It will be understood that although terms such as "first" and "second" may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element may be termed a second element, and similarly, a second element may be termed a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0033] The terms used herein are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting of the embodiments. The singular forms "a", "an", and "the" as used herein also include the plural forms unless the context clearly dictates otherwise. It is further understood that the terms "comprises", "comprising", "has", "having", "includes", and / or "including" when used herein specify the presence of the stated features, elements, and / or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0034] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0035] (a) A pure hardware circuit implementation (such as an implementation using only analog and / or digital circuitry), and

[0036] (b) A combination of hardware circuitry and software, such as (if applicable):

[0037] (i) A combination of (one or more) analog and / or digital hardware circuitry and software / firmware, and

[0038] (ii) Any portion of (one or more) hardware processors (including (one or more) digital signal processors), software, and (one or more) memories with software that work together to cause a device (such as a mobile phone or a server) to perform various functions, and

[0039] (c) (One or more) hardware circuits and / or (one or more) processors, such as (one or more) microprocessors or a portion of (one or more) microprocessors, which require software (e.g., firmware) to operate, but the software may be absent when not needed for operation.

[0040] The definition of circuitry is suitable for all uses of the term in this application, including in any claim. As another example, as used in this application, the term circuitry also encompasses implementations of only hardware circuits or processors (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also encompasses a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0041] As used herein, the term "communication network" refers to a network that follows any suitable communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed Packet Access (HSPA), NarrowBand Internet of Things (NB-IoT), etc. Additionally, communication between a terminal device and a network device in a communication network can be performed according to any suitable generation of communication protocol, including but not limited to third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocol, sixth generation (6G) communication protocol, and / or higher generation communication protocols. Embodiments of the present disclosure can be applied to various communication systems. Considering the rapid development of communications, of course, there will also be future types of communication technologies and systems that can be used to embody the present disclosure. It should not be construed as limiting the scope of the present disclosure to only the above systems.

[0042] As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services from the network. Depending on the terminology and technology applied, the network device can refer to a base station (BS) or an access point (AP), such as Node B (NodeB or NB), evolved Node B (eNodeB or eNB), NR NB (also known as gNB), remote radio unit (RRU), radio header (RH), remote radio head (RRH), relay, low power node (such as femto, pico), etc.

[0043] The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, IP voice (VoIP) phones, wireless local loop phones, tablet computers, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices (such as digital cameras), game terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, smart devices, wireless customer premise equipment (CPEs), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain environment), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment", and "UE" may be used interchangeably.

[0044] In the current NR system, multi-TRP operation has been introduced to improve the performance of the communication system. A cooperative transmission scheme can be used for multi-TRP. According to the mapping relationship between the transmit data layers and multiple transmission and reception points (TRPs), the multi-TRP cooperative transmission scheme can be divided into two types: coherent joint transmission (CJT) and non-coherent joint transmission (NCJT).

[0045] In CJT, the data transmitted by multiple TRPs is jointly beamformed, and the precoding matrices (relative phases) applied to different TRPs are coordinated so that the data in the same layer can be coherently combined at the terminal device receiving the transmitted data. In other words, the sub-arrays of multiple TRPs are modeled as a higher-dimensional antenna port array to obtain a higher beamforming gain. The CJT scheme generally has relatively high requirements for synchronization and cooperation between multiple TRPs. However, in the actual deployment environment of NR, the cooperation performance between TRPs is easily affected by non-ideal factors such as frequency deviation.

[0046] Beamforming can be referred to as spatial filtering, directional transmission, or directional reception. Beamforming is a signal processing technique that can be used at the transmitting device and / or receiving device to shape or steer an antenna beam along the spatial path between the transmitting device and the receiving device. Beamforming can rely on the antenna elements of an antenna array to make the signal propagate in a specific direction.

[0047] As used herein, the term "beam" may refer to communication resources. Different beams may be regarded as different resources. A beam may also be represented as a spatial filter. The technique used to form a beam may be a beamforming technique or another technique. The beamforming technique may specifically be a digital beamforming technique, an analog beamforming technique, or a hybrid digital / analog beamforming technique. A communication device (including a terminal device and a network device) may communicate with another communication device via one or more beams. A beam may include one or more antenna ports and is configured for a data channel, a control channel, etc. The one or more antenna ports forming a beam may also be regarded as an antenna port set. A beam may be configured with a resource set or a resource set for measurement, and a beam may be represented by, for example, a reference signal and / or related resources of the reference signal. A beam may also be represented by a reference cell identifier or a resource identifier.

[0048] In NR, a terminal device is provided with a reference signal (RS) via quasi-co-location (QCL) source information and may set a channel estimation filter and related parameters based on the RS to receive data transmissions (e.g., DMRS of PDSCH and PDSCH transmission).

[0049] Two antenna ports are called quasi-co-located if the attributes of the channel through which the symbols on one antenna port are conveyed can be inferred from the channel through which the symbols on the other antenna port are conveyed.

[0050] PDSCH transmissions from multiple TRPs in CJT are based on joint precoding over all antenna ports of the TRPs involved in CJT. The scheduler may dynamically make decisions on the downlink precoder and rank for each CJT PDSCH transmission based on the channel state information (CSI) report and hybrid automatic repeat request (HARQ) feedback (inner-loop link adaptation) of the terminal device. Therefore, the precoder may change from one PDSCH transmission moment to another PDSCH transmission moment.

[0051] Similarly, the empirical signal characteristics resulting from the combined effect of the radio channel and the precoder applied at the terminal device may also change according to the applied decoder. In addition, different numbers of TRPs may be involved in different PDSCH transmissions. Therefore, the terminal device needs to estimate the channel characteristics of PDSCH reception based on a set of TRP-specific tracking reference signals (TRS) that change from one PDSCH transmission to another.

[0052] Currently, the relationship between the QCL source RS and the target signal is one-to-one, and multiple QCL sources RS have nothing to do with a single target signal. Therefore, it poses challenges in estimating the channel characteristics of PDSCH reception based on a set of TRP-specific tracking reference signals (TRS) that change from time to time. Therefore, a solution is needed to enable channel characteristic estimation.

[0053] In an embodiment of the present disclosure, a QCL source configuration is used to notify a terminal device of valid QCL sources to facilitate QCL attribute estimation in coherent joint transmission. Specifically, according to an embodiment of the present disclosure, the terminal device receives a quasi-co-location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indicator (TCI) states, and the at least two TCI states indicate reference signals from valid QCL sources, and the reference signals are used for coherent joint transmission (CJT) of tracking reference signals (TRS). Then, the terminal device performs QCL attribute estimation on the received TRS based on the QCL source configuration.

[0054] Using this solution, the QCL source configuration is used to indicate valid QCL resources by means of TCI states, which can reflect both the changes in QCL resources and the changes in precoders in CJT transmission, and thus the terminal device can learn the relationship between QCL resources and the corresponding uplink transmission in CJT transmission. Therefore, the terminal device can estimate the channel characteristics of PDSCH reception based on a set of TRP-specific tracking reference signals (TRS).

[0055] As used herein, the term "quasi-co-location (QCL)" can define the relationship between two antenna ports (or reference signals) at a terminal device. If the attributes of the channel through which the symbols on one antenna port are transmitted (e.g., large-scale channel attributes) can be inferred from the channel through which the symbols on the other antenna port are transmitted, then these two antenna ports can be called QCL. There are four types of QCL information corresponding to RS, including type A, B, C, and D, and the QCL information can be used by the terminal device to facilitate CJT PDSCH transmission. For example, the terminal device can use the QCL information for CSI acquisition and channel condition estimation.

[0056] Hereinafter, for the purpose of illustration, the following will refer to Figures 1 - 8 Describe the principles and exemplary embodiments of the present disclosure for channel information prediction. However, it should be noted that these embodiments are given to enable those skilled in the art to understand the inventive concept of the present disclosure and implement the solutions proposed herein, and are not intended to limit the scope of the present application in any way.

[0057] Figure 1FIG. illustrates an example communication network environment 100 in which example embodiments of the present disclosure may be implemented. The communication network environment 100 (which may be part of a communication network) includes terminal devices and network devices.

[0058] As Figure 1 shown, the communication network environment 100 may include a network device 110 and terminal devices 120. In some embodiments, the network device 110 may include, but is not limited to, an NR NB (also referred to as a gNB), and the terminal device 120 may include, but is not limited to, a user equipment (UE). The network device 110 may communicate with the terminal device 120. In the communication network environment 100, the link from the network device 110 to the terminal device 120 may be referred to as a downlink, and the link from the terminal device 120 to the network device 110 may be referred to as an uplink.

[0059] In the downlink, the network device 110 is a transmitting (TX) device (or transmitter), and the terminal device 120 is a receiving (RX) device (or receiver). In the uplink, the terminal device 120 is a transmitting TX device (or transmitter), and the first network device 110 is an RX device (or receiver). In some embodiments, the network device 110 and the terminal device 120 may communicate using a direct link / channel.

[0060] As Figure 1 the example of Figure 1 shows, the communication network environment 100 may support multi-TRP transmission. As Figure 1 shown, the terminal device 120 may communicate with, for example, four TRPs (i.e., TRP 130-1, 130-2, 130-3, and 130-4 (collectively or individually referred to as TRP130)). For illustrative purposes, TRP 130-1 may be referred to as the first TRP 130-1, TRP 130-2 may be referred to as the second TRP 130-2, TRP 130-3 may be referred to as the third TRP 130-3, and TRP 130-4 may be referred to as the fourth TRP 130-4.

[0061] It should be understood that although Figure 1 shows four TRPs, the number of TRPs in the embodiments of the present disclosure is not limited to four, and any other number of TRPs may be used in the communication network environment 100.

[0062] In some embodiments, the terminal device 120 may be served by multiple TRPs. The multiple TRPs may be associated with the network device 110. For example, the network device 110 may be associated with multiple TRPs to communicate with the terminal device 120. For example, as Figure 1As shown, the network device is associated with the first TRP 130-1, the second TRP 130-2, the third TRP 130-3, and the fourth TRP 130-4.

[0063] In some embodiments, some of the multiple TRPs can be associated with the network device in a cell, and some of the multiple TRPs can be associated with another network device in another cell. For example, the network device 110 can be associated with the first TRP 130-1 and the second TRP 130-2, while another network device (not shown) can be associated with the third TRP 130-3 and the fourth TRP 130-4.

[0064] In some embodiments, the network device can be associated with multiple TRPs at different geographical locations to achieve better coverage. In alternative embodiments, the network device 110 can be associated with multiple TRPs distributed at the same geographical location to achieve relatively fast communication speeds.

[0065] It should be understood that Figure 1 the number of terminal devices 120, the number of network devices 110, and the number of TRPs 130 shown in the communication network environment 100 in [[ ]] are for illustrative purposes only and do not limit the scope of the present disclosure. In some example embodiments, the communication network environment 100 can include any number of terminal devices, any number of network devices, and / or any number of TRPs. And furthermore, each network device 110 according to the embodiments of the present disclosure can support any number of TRPs.

[0066] In addition, the communication between the devices in the communication environment 100 can be implemented according to any suitable communication protocol, including but not limited to cellular communication protocols of the third generation (3G), fourth generation (4G), fifth generation (5G), sixth generation (6G), etc., wireless local area network communication protocols (such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc.), and / or any other protocol known currently or developed in the future. In addition, the communication can utilize any suitable wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), and / or any other technology known currently or developed in the future.

[0067] In some embodiments, network device 110 sends a QCL source configuration indicating at least two transmission configuration indication (TCI) states from the network device. In some embodiments, the at least two TCI states indicate reference signals for CJT TRS from a valid QCL source. Then, terminal device 120 performs QCL attribute estimation on the received TRS based on the QCL source configuration.

[0068] Figure 2 FIG. illustrates an example signaling procedure 200 for coherent joint transmission according to some embodiments of the present disclosure. For the purpose of discussion, procedure 200 will be described with reference to Figure 1 Procedure 200. Procedure 200 may involve network device 110 and terminal device 120 as shown in Figure 1 FIG. More specifically, procedure 200 may involve terminal device 120, network device 110, and four TRPs 130-1 to 130-4 as shown in Figure 1 FIG. In some embodiments, network device 110 may support multiple TRPs 130-1 to 130-4.

[0069] It can be understood that although only one terminal device 120 is shown in Figure 2 FIG., network device 110 may communicate with more than one terminal device. Similarly, although only one network device 110 is shown in Figure 2 FIG., there may be more than one network device to support multiple TRPs, such as 4 TRPs. In addition, although procedure 200 is described in conjunction with communication network environment 100 in Figure 1 FIG., procedure 200 may equally be applied to other communication network scenarios with similar QCL source configuration requirements. In addition, in procedure 200, one or more operations may be added, omitted, modified, or these operations may also be performed in any suitable order without departing from the scope of the present disclosure.

[0070] In procedure 200, at 210, terminal device 120 may report capability information to network device 110. The capability information may indicate that terminal device 120 supports CJT TRS transmission and reception as well as CJT PDSCH transmission. Network device 110 may receive the capability information from terminal device 120 and configure terminal device 120 to perform CJT transmission and reception according to the capability information, which will be explained in detail below with reference to signaling procedure 200.

[0071] In some embodiments, at 222, network device 110 may send CJT TRS resource configuration to terminal device 120 for configuration. The CJT TRS resource includes CSI-RS resources specifically designed for time-frequency tracking. In some embodiments, the CJT TRS resource configuration may include a periodic configuration, i.e., the terminal device 120 may be configured with periodic TRS resources. For example, network device 110 associated with four TRPs 130-1 to 130-4 may be configured with multiple TRS resource sets for terminal device 120, each resource set having four periodic TRSs in one time slot.

[0072] In some embodiments, network device 110 may send the CJT TRS resource configuration in a Radio Resource Control (RRC) message. The TRS resource configuration may indicate one or more TRS resource sets, and each TRS resource set may include, for example, four periodic non-zero power channel state information reference signals (NZP CSI-RS) resources in two consecutive time slots, with two periodic NZP CSI-RS resources in each time slot.

[0073] In some embodiments, the network device 110 may be sent the TRS resource configuration in a Downlink Control Information (DCI) message. The TRS resource configuration may indicate either or both of the identity of the NZP CSI-RS resource set or the identity of the NZP CSI-RS resource. For example, the TRS resource configuration may indicate the identity of the NZP CSI-RS resource set. For another example, the TRS resource configuration may indicate the identity of the NZP CSI-RS resource. As another example, the TRS resource configuration may indicate both the identity of the NZP CSI-RS resource set and the identity of the NZP CSI-RS resource.

[0074] In some embodiments, the CJT TRS resource configuration may include an aperiodic configuration, i.e., the terminal device 120 may be configured with aperiodic TRS resources. For example, for network device 110 associated with four TRPs 130-1 to 130-4, multiple TRS resource sets may be configured for terminal device 120, each resource set having four aperiodic TRSs. The network device 110 may send the aperiodic CJT TRS resource configuration after the Transmission Configuration Indication (TCI) state of the TRP (which will be described in detail below). Alternatively, the network device 110 may send the aperiodic CJT TRS resource configuration without any TCI state.

[0075] In some embodiments, at 224, network device 110 may send a TCI state configuration to terminal device 120. The TCI state configuration indicates multiple potential TCI states of the terminal device. For example, the TCI states of the TCI state configuration may correspond to multiple TRPs that the terminal device can support. The TCI state may be indicated by a Media Access Control (MAC) Control Element (CE) or DCI, and may be applied to CJT PDSCH reception at terminal device 120.

[0076] Depending on the capabilities of terminal device 120, one or more joint TCI states may be configured for terminal device 120 to provide QCL information (e.g., QCL parameters) for the reception of DMRS and PDSCH at terminal device 120. For Figure 1 the scenario shown, if terminal device 120 can support four TRPs, then terminal device 120 may be configured with, for example, four TCI states.

[0077] In some embodiments, each TCI state in the TCI state configuration may indicate a reference signal from one valid QCL source. Thus, each TCI state may be associated with one TRS resource in the TRS resource configuration. Specifically, for N TRPs (N is an integer greater than 1), N TRS resources are configured for terminal device 120, and each TRS may provide information related to the channel characteristics of the TRP. Thus, for the purpose of CSI acquisition, for each TRP-specific CSI-RS resource set and the corresponding (one or more) CSI-RS resources, the TRP-specific QCL source RS may be provided through the TCI state. For example, a QCL type A source RS may be provided for the TRS to obtain CSI acquisition and the DMRS of the PDSCH, and a QCL type D source RS may be provided for the TRS to obtain the channel conditions and support beamforming.

[0078] In some embodiments, the QCL source RS types associated with the TRS resources may include the following formats and parameters:

[0079] - 'Type A': {Doppler shift, Doppler spread, average delay, delay spread}

[0080] - 'Type B': {Doppler shift, Doppler spread}

[0081] - 'Type C': {Doppler shift, average delay}

[0082] - 'Type D': {Spatial Rx parameters}

[0083] It should be understood that these examples of the QCL source RS type associated with the TRS resource as described above are for illustrative purposes only. As technology develops, the QCL source RS type associated with the TRS resource may include other formats and / or parameters.

[0084] In some embodiments, at 226, the network device 110 may send CSI-RS resource configuration to the terminal device 120. The terminal device 120 may perform measurements on the CSI-RS and report the results of the measurements of the CSI-RS set to the network device 110, as shown at 230 of the signaling procedure 200.

[0085] At 240, the network device 110 may determine one or more CJT parameters for CJT transmission based on the received measurement results. In some embodiments, the one or more CJT parameters may include one or more of the following: the precoder of the CJT, the rank, or the modulation and coding scheme (MCS) of the CJT. It should be understood that these parameters are only some examples given for illustrative purposes, and the network device 110 may determine other parameters related to the CJT at 240.

[0086] In some embodiments, as shown at 242, the network device 110 may send a transmission mode configuration to the terminal device 120. In some embodiments, the transmission mode configuration may indicate a set of potential transmission modes, including one or more of the following: the CJT mode, the non-coherent joint transmission (NCJT) mode, or the dynamic point selection mode. The terminal device 120 may be indicated to have a transmission mode and perform transmission according to the selection of the transmission mode indicated by the network device 110.

[0087] In some embodiments, after the transmission of the transmission mode configuration, the network device 110 may send a transmission mode indication to the terminal device 120, which may trigger the CJT mode. Specifically, when two or more QCL sources are valid, the transmission mode indication is sent to the terminal device 120, and the transmission mode indication may indicate the type of joint transmission, that is, whether the joint transmission type is the CJT mode or the NCJT mode. In the case of the CJT mode, the above solution will be executed; otherwise, a traditional solution may be applied.

[0088] At 244, the network device 110 sends a QCL source configuration to the terminal device 120 based on the results of the measurements of the CSI-RS set. The QCL source configuration may indicate at least two TCI states, and the at least two TCI states indicate reference signals for CJT of the TRS from valid QCL sources.

[0089] In some embodiments, the QCL source configuration may be indicated by a bitmap. In some embodiments, one bit in the bitmap is associated with one of a plurality of potential TCI states. The number of bits in the bitmap may be determined according to the number of the plurality of potential TCI states. For example, if there are four potential TCI states, a bitmap of size four is required, and each bit may correspond to a TCI state and be used to indicate whether the TCI state is activated and thus whether the associated QCL source is valid. In some embodiments, the number of bits in the bitmap may be determined according to the number of a plurality of potential TRPs. For example, if there are four potential TRPs, a bitmap of size four is required, and each bit in the bitmap may correspond to a TRP and be used to indicate whether the TRP is a valid QCL source.

[0090] In an alternative embodiment, when two or more QCL sources are valid, the transmission mode indication may be sent to the terminal device 120 according to the QCL source configuration. In this case, the transmission mode indication may indicate the type of joint transmission, that is, whether the joint transmission type is the CJT mode or the NCJT mode.

[0091] Now reference will be made to Figures 3A - 3C describe the QCL source configuration in detail. Figures 3A - 3C FIG. illustrates an example scenario of multiple TRPs in CJT according to an embodiment of the present disclosure. For clarity, the network device associated with four TRPs is not shown in Figures 3A - 3C is not shown.

[0092] As Figure 3A shown, four TRPs are used in CJT, and each TRP sends a TRS to the terminal device 120. Therefore, the bitmap indicating the QCL source configuration may have four bits, and in this case, it may be, for example, "1111". The bitmap indicates that all four TCI states are configured for CJT transmission, and thus all four TRPs associated with the four TCI states are valid QCL sources.

[0093] For example, the QCL source configuration indicates, for example, a first TCI state corresponding to the first TRP 130-1, a second TCI state corresponding to the second TRP 130-2, a third TCI state corresponding to the third TRP 130-3, and a fourth TCI state corresponding to the fourth TRP 130-4. The indicated TCI states may include or indicate information about the reference signals from the corresponding valid QCL sources. For example, the first TCI state may indicate the reference signal from the first TRP 130-1, the second TCI state may indicate the reference signal from the TRP 130-2, the third TCI state may indicate the reference signal from the TRP 130-3, and the fourth TCI state may indicate the reference signal from the TRP 130-4.

[0094] In some embodiments, for the purpose of CSI acquisition, each indicated reference signal from a corresponding valid source is provided with a TRP-specific TRS resource or resource set. For example, a QCL type A source RS can be provided for the TRS to obtain CSI acquisition and the DMRS of PDSCH, and a QCL type D source RS can be provided for another TRS to obtain channel conditions and support beamforming.

[0095] Similarly, as Figure 3B shown, at different transmission instants, three TRPs are used to send TRS to the terminal device 120 in CJT. Thus, the bitmap indicating the QCL source configuration can be, for example, "1101", which indicates that the three shown TRPs are valid QCL sources.

[0096] Specifically, the QCL source configuration can indicate three TCI states. For example, a first TCI state corresponding to the first TRP 130-1, a second TCI state corresponding to the second TRP 130-2, and a fourth TCI state corresponding to the fourth TRP 130-4. And the indicated TCI states can indicate reference signals from the corresponding valid sources. For example, the first TCI state can indicate a reference signal from the first TRP 130-1, the second TCI state can indicate a reference signal from the second TRP 130-2, and the fourth TCI state can indicate a reference signal from the fourth TRP 130-4.

[0097] Similarly, for the purpose of CSI acquisition performed by the terminal device 110, each TRP-specific TRS set is provided with the indicated reference signal from the corresponding valid source. For example, a QCL type A source RS can be provided for the TRS to obtain CSI acquisition and the DMRS of PDSCH, and a QCL type D source RS can be provided for another TRS to obtain channel conditions and support beamforming.

[0098] Now referring to Figure 3C , at another transmission instant, two TRPs are used to send TRS to the terminal device 120 in CJT. Thus, the bitmap indicating the QCL source configuration can be, for example, "1001", which indicates that two TRPs (i.e., the first TRP 130-1 and the fourth TRP 130-4) are valid QCL sources.

[0099] Specifically, the QCL source configuration can indicate two TCI states. For example, a first TCI state corresponding to the first TRP 130-1 and a fourth TCI state corresponding to the fourth TRP 130-4. And the indicated TCI states can indicate reference signals from the corresponding active sources. For example, the first TCI state can indicate a reference signal from the first TRP 130-1, and the fourth TCI state can indicate a reference signal from the fourth TRP 130-4.

[0100] Similarly, for the purpose of CSI acquisition by the terminal device 110, the indicated reference signals from two corresponding active sources are provided for each TRP-specific TRS set. For example, a QCL type A source RS can be provided for the TRS to obtain CSI acquisition and the DMRS of the PDSCH, and a QCL type D source RS can be provided for another TRS to obtain channel conditions and support beamforming.

[0101] As Figure 3A shown, since all four TRPs are active QCL sources for transmitting TRS, the scenario shown in Figure 3A can also be used in the initial configuration phase to configure the TRS resource configuration for the terminal device 120. In addition, when used in the initial configuration phase, the four TRPs can also send CSI-RS ( Figure 3A not shown in the figure) to the terminal device 120 for CSI acquisition. In addition, it should be understood that according to specific applications and requirements, other signals and configurations transmitted between the TRP and the network device 120 are also possible. For simplicity, these signals and configurations transmitted between the TRP and the network device 120 will not be described in detail in Figure 3A the figure.

[0102] In some embodiments, the network device 110 can activate the active QCL source through any one of the media access control (MAC) control element (CE) or DCI message. For example, the activation can be achieved through one or more code points. For example, the DCI message can configure the code points corresponding to the QCL source. Therefore, by configuring the code points, the corresponding QCL source can be activated or deactivated.

[0103] In some embodiments, the bit width of the code points in the DCI can be configurable. For example, the code point "00" can activate the second QCL source and the fourth QCL source, while the code point "01" can activate the third QCL source and the fourth QCL source. The MAC CE can be used to activate the active source in a similar manner as described in the reference DCI. For simplicity, the repeated description will not be elaborated in detail.

[0104] Referring again to Figure 2, at 246, the active TRP may send CJT TRS. The CJT TRS is associated with the indicated TCI state. At 250 of the signaling procedure 200, the terminal device 120 performs QCL property estimation on the received TRS based on the QCL source configuration. In some embodiments, the QCL property estimation includes the estimation of one or more of the following: Doppler shift, Doppler spread, average delay, delay spread, or spatial reception parameters. The QCL property estimation can be used by the terminal device 120 to set the channel estimation filter for detecting and receiving DMRS and PDSCH.

[0105] At 260, the network device 110 may send a scheduling command for PDSCH transmission, and send DMRS and schedule PDSCH. Thus, the terminal device 120 may receive the scheduling command for PDSCH transmission, and receive DMRS and schedule PDSCH based on the QCL property estimation.

[0106] In some embodiments, the scheduled CJT PDSCH and the demodulation reference signal (DMRS) associated with the scheduled CJT PDSCH may be received at the antenna port of the received TRS. For example, the same precoder associated with the layer of the scheduled PDSCH may be used to send CJT TRS. That is, the CJT TRS has the antenna weights of the first layer of the PDSCH, or has the DMRS of the first layer of the scheduled PDSCH. Thus, the terminal device 120 may receive DMRS and the scheduled CJT PDSCH associated with the DMRS at the antenna port of the received CJT TRS.

[0107] In some embodiments, when scheduling PDSCH in DCI, it may determine the association between the TRS associated with the PDSCH and the DMRS. It is known that the DMRS is used for demodulation of the PDSCH, and thus, according to the DCI scheduling the PDSCH, it can be known which (which) DMRS is associated with the scheduled PDSCH. The latest TRS received in at most a predetermined number of time slots before the transmission of the scheduled CJT PDSCH may be determined as the associated TRS. In this way, the latest TRS can be associated with the DMRS. In this embodiment, the TRS does not require explicit signaling (such as a separate DCI) to trigger, and thus the association can be defined in an implicit manner.

[0108] Alternatively, a separate triggering signaling (e.g., DCI) can be used to trigger the TRS. In this case, for the scheduled PDSCH, the associated TRS can be received in up to a predetermined number of time slots before transmitting the scheduled CJT PDSCH and the TRS triggering indication indicates the last triggered TRS. In this way, the TRS can also be associated with the DMRS. In this solution, a separate triggering signaling is used to trigger the TRS, and thus this association is defined in an explicit manner.

[0109] It should be understood that by transmitting the TRS at a predetermined number of time slots before transmitting the scheduled CJT PDSCH, the network device 110 can have a period of time for preparing the transmission to ensure the accuracy of the transmission. In addition, it should also be understood that any other scheme for determining the association between the CJT TRS and the DMRS can also be used herein.

[0110] For example, Figure 4 FIG. 400 is an example schematic diagram showing the reception of CJT TRS and DMRS according to an embodiment of the present disclosure. As Figure 4 shown, three TRP-specific TRSs are used in the CJT transmission. For example, the first TRP 130-1 transmits TRS#1, the second TRP 130-2 transmits TRS#2, and the fourth TRP 130-4 transmits TRP#4. At 440, the three CJT TPRs are received at the corresponding antenna ports and measured by the terminal device. The QCL attributes can be estimated based on the measurement of the TRSs from the three active TRPs. The terminal device 120 can also receive (450) the DMRS of the PDSCH and the scheduled PDSCH associated with the DMRS at the antenna port of the received TRS, for example, using the same precoder also used by the terminal device 120 to receive the TRS.

[0111] It should be understood that although Figure 4 three TRP-specific TRSs are shown, at another different time point, there can be other numbers of TRP-specific TRSs. However, the operations are similar, but the number of active TRPs is different. For simplicity, it will not be described in detail here.

[0112] Advantageously, by receiving the QCL source configuration indicating at least two TCI states, the terminal device can learn the reference signal for the CJT of the TRS from the active source, and the terminal device 120 can then perform QCL attribute estimation based on the QCL source configuration. Therefore, the CJT DMRS and the CJT PDSCH can be received based on this estimation, and thus the transmission performance and efficiency can be significantly improved.

[0113] Figure 5FIG. 500 is a flowchart of an exemplary method implemented at a terminal device (e.g., terminal device 120) in accordance with some embodiments of the present disclosure. For purposes of discussion, method 500 will be described from the perspective of terminal device 120. Figure 1 Method 500 will be described from the perspective of terminal device 120.

[0114] At 520, terminal device 120 receives a quasi co-location (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source for coherent joint transmission (CJT) of tracking reference signals (TRS).

[0115] In some embodiments, the QCL source configuration may be indicated by a bitmap, and one bit in the bitmap is associated with one of a plurality of potential TCI states.

[0116] At 540, terminal device 120 performs QCL attribute estimation on the received TRS based on the QCL source configuration. In some embodiments, the QCL attribute estimation may include estimation of one or more of the following: Doppler shift, Doppler spread, average delay, delay spread, or spatial reception parameters.

[0117] In some embodiments, terminal device 120 may receive a TRS resource configuration for QCL attribute estimation of CJT.

[0118] In some embodiments, the TRS resource configuration may be received in a radio resource control (RRC) message and may indicate one or more TRS resource sets, and each TRS resource set may include four periodic non-zero power channel state information reference signals (NZP CSI-RS) resources in two consecutive time slots, with two periodic NZP CSI-RS resources in each time slot.

[0119] In some embodiments, the TRS resource configuration may be received in a downlink control information (DCI) message and may indicate either the identity of the NZP CSI-RS resource set or the identity of the NZP CSI-RS resource, or both.

[0120] In some embodiments, terminal device 120 may also send capability information to the network device, where the capability information may indicate that the terminal device supports CJT TRS transmission and CJT physical downlink shared channel (PDSCH) transmission.

[0121] In some embodiments, terminal device 120 may also receive a TCI state configuration indicating a plurality of potential TCI states of the terminal device, where each TCI state in the TCI state configuration may be associated with a TRS resource in the TRS resource configuration.

[0122] In some embodiments, the terminal device 120 may also receive CSI-RS from the network device, perform measurements on the CSI-RS, and report the measurement results to the network device.

[0123] In some embodiments, the terminal device 120 may also receive a transmission mode configuration from the network device, where the transmission mode configuration may indicate a set of transmission modes, including one or more of the following: CJT mode, non-coherent joint transmission NCJT mode, or dynamic point selection mode.

[0124] In some embodiments, the terminal device 120 may also receive a transmission mode indication from the network device, where the transmission mode indication may trigger the CJT mode.

[0125] In some embodiments, the terminal device 120 may also receive a demodulation reference signal (DMRS) and a scheduled CJT PDSCH associated with the DMRS at the antenna port of the received TRS.

[0126] In some embodiments, the received TRS may include the latest TRS received in up to a predetermined number of time slots before the transmission of the scheduled CJT PDSCH.

[0127] In some embodiments, where the received TRS may include the last triggered TRS received in up to a predetermined number of time slots before the transmission of the scheduled CJT PDSCH and indicated by a TRS trigger indication, and / or where the TRS trigger indication may be separated from the scheduling command for scheduling the CJT PDSCH.

[0128] In some embodiments, the terminal device 120 may also receive a scheduling command for PDSCH transmission and receive the DMRS and PDSCH based on QCL attribute estimation.

[0129] Advantageously, by receiving a QCL source configuration indicating at least two TCI states, where the at least two TCI states indicate reference signals for CJT of the TRS from a valid source, the terminal device 120 may perform QCL attribute estimation based on the QCL source configuration, and thus, the transmission efficiency may be significantly improved.

[0130] Figure 6 A flowchart of an example method 600 implemented at a network device (e.g., network device 110 that may be associated with multiple TRPs for CJT) according to some embodiments of the present disclosure is shown. For purposes of discussion, method 600 will be described from the perspective of Figure 1 the network device 110.

[0131] At 620, the network device 130 receives the result of the measurement of the channel state information reference signal (CSI-RS) set from the terminal device.

[0132] At 640, the network device 110 sends a quasi co-location (QCL) source configuration to the terminal device. The QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the result of the measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signal is used for the coherent joint transmission (CJT) of the tracking reference signal (TRS).

[0133] In some embodiments, the QCL source configuration may be indicated by a bitmap, and one bit in the bitmap may be associated with one of a plurality of potential TCI states.

[0134] In some embodiments, the network device 110 may also send a TRS resource configuration for QCL attribute estimation for CJT to the terminal device.

[0135] In some embodiments, the QCL attribute estimation may include the estimation of one or more of the following: Doppler frequency shift, Doppler spread, average delay, delay spread, or spatial reception parameters.

[0136] In some embodiments, the TRS resource configuration may be sent in a radio resource control (RRC) message, and may indicate one or more TRS resource sets, and each TRS resource set may include four periodic non-zero power channel state information reference signal (NZP CSI-RS) resources in two consecutive time slots, and there are two periodic NZP CSI-RS resources in each time slot.

[0137] In some embodiments, the TRS resource configuration may be sent in a downlink control information (DCI) message, and may indicate either the identity of the NZP CSI-RS resource set or the identity of the NZP CSI-RS resource, or both.

[0138] In some embodiments, the network device 110 may also receive capability information from the terminal device, where the capability information may indicate that the terminal device supports CJT TRS transmission and CJT physical downlink shared channel (PDSCH) transmission.

[0139] In some embodiments, the network device 110 may also send a TCI state configuration indicating multiple potential TCI states of the terminal device, where each TCI state in the TCI state configuration may be associated with a TRS resource in the TRS resource configuration.

[0140] In some embodiments, the network device 110 may also send CSI-RS to the terminal device.

[0141] In some embodiments, the network device 110 may further determine one or more CJT parameters based on the received measurement results, where the one or more CJT parameters may include one or more of the following: the precoder of the CJT, the rank, or the modulation and coding scheme (MCS) of the CJT.

[0142] In some embodiments, the network device 110 may further send a transmission mode configuration to the terminal device, where the transmission mode configuration may indicate a set of transmission modes, including one or more of the following: the CJT mode, the non-coherent joint transmission (NCJT) mode, or the dynamic point selection mode.

[0143] In some embodiments, the network device 110 may send a transmission mode indication to the terminal device, where the transmission mode may indicate triggering the CJT mode.

[0144] In some embodiments, the network device 110 may further send a demodulation reference signal (DMRS) and a scheduled CJT PDSCH associated with the DMRS at the antenna port of the transmitted TRS.

[0145] In some embodiments, the transmitted TRS may include the latest TRS transmitted in a maximum number of time slots before the transmission of the scheduled CJT PDSCH.

[0146] In some embodiments, the transmitted TRS may include the last triggered TRS transmitted in a maximum number of time slots before the transmission of the scheduled CJT PDSCH and triggered by the TRS indication, where the scheduling command may be separated from the DCI that triggers the TRS.

[0147] In some embodiments, the network device 110 may further send a scheduling command for PDSCH transmission and send the DMRS and PDSCH based on QCL attribute estimation.

[0148] In some embodiments, the network device 110 may further activate a valid QCL source through any one of a media access control (MAC) control element (CE) or a DCI message.

[0149] Advantageously, by means of a QCL source configuration indicating at least two TCI states, where the at least two TCI states indicate reference signals for CJT of the TRS from a valid source, the terminal device 120 performs QCL attribute estimation based on the QCL source configuration. Therefore, the transmission efficiency can be significantly improved.

[0150] In some embodiments, a device (e.g., the terminal device 120) capable of performing any operation of method 500 may include components for performing the corresponding steps of method 500. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0151] In some embodiments, the device includes components for receiving a quasi co-location (QCL) source configuration from a network device. The QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of tracking reference signals (TRS). The device further includes components for performing QCL attribute estimation on the received TRS based on the QCL source configuration.

[0152] In some embodiments, the QCL source configuration may be indicated by a bitmap, and one bit in the bitmap is associated with one of a plurality of potential TCI states.

[0153] In some embodiments, the QCL attribute estimation may include estimation of one or more of the following: Doppler shift, Doppler spread, average delay, delay spread, or spatial reception parameters.

[0154] In some embodiments, the device may further include components for receiving a TRS resource configuration for QCL attribute estimation for CJT.

[0155] In some embodiments, the TRS resource configuration may be received in a radio resource control (RRC) message, and may indicate one or more TRS resource sets, and each TRS resource set may include four periodic non-zero power channel state information reference signals (NZP CSI-RS) resources in two consecutive time slots, with two periodic NZP CSI-RS resources in each time slot.

[0156] In some embodiments, the TRS resource configuration may be received in a downlink control information (DCI) message, and indicates either the identity of the NZP CSI-RS resource set or the identity of the NZP CSI-RS resource, or both.

[0157] In some embodiments, the device may further include components for sending capability information to the network device, where the capability information may indicate that the terminal device supports CJT TRS transmission and CJT physical downlink shared channel (PDSCH) transmission.

[0158] In some embodiments, the apparatus may further include components for receiving a TCI state configuration indicating a plurality of potential TCI states of a terminal device, wherein each TCI state in the TCI state configuration may be associated with one TRS resource in a TRS resource configuration.

[0159] In some embodiments, the apparatus may further include components for receiving CSI-RS from a network device, components for performing measurements on the CSI-RS, and components for reporting the measurement results to the network device.

[0160] In some embodiments, the apparatus may further include components for receiving a transmission mode configuration from a network device, where the transmission mode configuration may indicate a set of transmission modes, including one or more of the following: CJT mode, non-coherent joint transmission NCJT mode, or dynamic point selection mode.

[0161] In some embodiments, the apparatus may further include components for receiving a transmission mode indication from a network device, where the transmission mode indication may trigger the CJT mode.

[0162] In some embodiments, the apparatus may further include components for receiving a demodulation reference signal (DMRS) at an antenna port receiving the TRS and a scheduled CJT PDSCH associated with the DMRS.

[0163] In some embodiments, the received TRS may include the latest TRS received in up to a predetermined number of time slots before transmitting the scheduled CJT PDSCH.

[0164] In some embodiments, the received TRS may include the last-triggered TRS received in up to a predetermined number of time slots before transmitting the scheduled CJT PDSCH and indicated by a TRS trigger, and / or where the TRS trigger indication may be separated from the scheduling command for scheduling the CJT PDSCH.

[0165] In some embodiments, the apparatus may further include components for receiving a scheduling command for PDSCH transmission and receiving the DMRS and PDSCH based on QCL attribute estimation.

[0166] Advantageously, by receiving a QCL source configuration indicating at least two TCI states, where the at least two TCI states indicate reference signals for CJT of the TRS from a valid source, the terminal device 120 may perform QCL attribute estimation based on the QCL source configuration, and thus, the transmission efficiency may be significantly improved.

[0167] In some embodiments, an apparatus (e.g., network device 110 associated with multiple TRPs for CJT) capable of performing any one of the methods in method 600 may include components for performing the corresponding steps of method 600. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0168] In some embodiments, the apparatus may include components for receiving, from a terminal device, results of measurements on a channel state information reference signal (CSI-RS) set. The apparatus may further include components for sending, to the terminal device, a quasi-co-location (QCL) source configuration. The QCL source configuration indicates at least two transmission configuration indication (TCI) states based on the results of measurements on the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source for coherent joint transmission (CJT) of a tracking reference signal (TRS).

[0169] In some embodiments, the QCL source configuration may be indicated by a bitmap, and one bit in the bitmap is associated with one of a plurality of potential TCI states.

[0170] In some embodiments, the apparatus may further include components for sending, to the terminal device, a TRS resource configuration for QCL attribute estimation for CJT.

[0171] In some embodiments, the QCL attribute estimation may include an estimation of one or more of the following: Doppler shift, Doppler spread, average delay, delay spread, or spatial reception parameters.

[0172] In some embodiments, the TRS resource configuration may be sent in a radio resource control (RRC) message and may indicate one or more TRS resource sets, and each TRS resource set may include four periodic non-zero power channel state information reference signal (NZP CSI-RS) resources in two consecutive time slots, with two periodic NZP CSI-RS resources in each time slot.

[0173] In some embodiments, the TRS resource configuration may be sent in a downlink control information (DCI) message and may indicate either the identity of an NZP CSI-RS resource set or the identity of an NZP CSI-RS resource, or both.

[0174] In some embodiments, the apparatus may further include components for receiving, from the terminal device, capability information, where the capability information may indicate that the terminal device supports CJT TRS transmission and CJT physical downlink shared channel (PDSCH) transmission.

[0175] In some embodiments, the apparatus may further include components for sending a TCI state configuration indicating multiple potential TCI states of a terminal device, where each TCI state in the TCI state configuration may be associated with one TRS resource in the TRS resource configuration.

[0176] In some embodiments, the apparatus may further include components for sending CSI-RS to the terminal device.

[0177] In some embodiments, the apparatus may further include components for determining one or more CJT parameters based on the results of received measurements, where the one or more CJT parameters may include one or more of the following: a precoder of the CJT, a rank, or a modulation and coding scheme (MCS) of the CJT.

[0178] In some embodiments, the apparatus may further include components for sending a transmission mode configuration to the terminal device, where the transmission mode configuration may indicate a set of transmission modes, including one or more of the following: a CJT mode, a non-coherent joint transmission (NCJT) mode, or a dynamic point selection mode.

[0179] In some embodiments, the apparatus may further include components for sending a transmission mode indication to the terminal device, where the transmission mode may indicate triggering the CJT mode.

[0180] In some embodiments, the apparatus may further include components for sending a demodulation reference signal (DMRS) and a scheduled CJT PDSCH associated with the DMRS at an antenna port of the transmitted TRS.

[0181] In some embodiments, the transmitted TRS may include the latest TRS transmitted in at most a predetermined number of time slots before transmitting the scheduled CJT PDSCH.

[0182] In some embodiments, the transmitted TRS may include the last-triggered TRS transmitted in at most a predetermined number of time slots before transmitting the scheduled CJT PDSCH and triggered by the TRS, where the scheduling command may be separated from the DCI triggering the TRS.

[0183] In some embodiments, the apparatus may further include components for sending a scheduling command for PDSCH transmission and for sending the DMRS and PDSCH based on QCL attribute estimation.

[0184] In some embodiments, the apparatus may further include components for activating a valid QCL source through any one of a media access control (MAC) control element (CE) or a DCI message.

[0185] It should be understood that, for simplicity, the operations at the network device are briefly described above. These operations on the network side may correspond to the operations at the terminal device. Therefore, for the detailed operations of some operations or features in Figure 6 reference may be made to the above references Figure 2 and Figure 5 for the content described for the terminal device.

[0186] Advantageously, by means of a QCL source configuration indicating at least two TCI states, where the at least two TCI states indicate reference signals for CJT of TRS from a valid source, the terminal device 120 can perform QCL property estimation based on the QCL source configuration, and thus, the transmission efficiency can be significantly improved.

[0187] In some embodiments, an apparatus (e.g., the terminal device 120) capable of performing method 500 may include components for performing the corresponding steps of method 500. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0188] In certain embodiments, the apparatus may further include components for performing the steps in some embodiments of method 500. In some embodiments, the apparatus may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to perform.

[0189] In some embodiments, the apparatus for performing method 500 includes: a component for receiving a quasi - co - located (QCL) source configuration from a network device. The QCL source configuration indicates at least two transmission configuration indicator (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source for coherent joint transmission (CJT) of a tracking reference signal (TRS). The apparatus may further include a component for performing QCL property estimation on the received TRS based on the QCL source configuration.

[0190] In some embodiments, an apparatus (e.g., the network device 110) capable of performing method 600 may include components for performing the corresponding steps of method 600. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0191] In some embodiments, the apparatus may further include components for performing the steps in some embodiments of method 600. In some embodiments, the apparatus may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to perform.

[0192] In some embodiments, the apparatus for performing method 600 includes: components for receiving, from a terminal device, the results of measurements on a channel state information reference signal (CSI-RS) set. The apparatus may further include components for sending, to the terminal device, a quasi-co-location (QCL) source configuration. The QCL source configuration indicates at least two transmission configuration indicator (TCI) states based on the results of measurements on the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, the reference signals being for tracking coherent joint transmission (CJT) of a tracking reference signal (TRS).

[0193] Figure 7 is a simplified block diagram of a device 700 suitable for implementing embodiments of the present disclosure. The device 700 may be provided to implement a communication device, such as Figure 1 the terminal device 120 shown. As shown, the device 700 includes one or more processors 710, one or more memories 720 coupled to the processors 710, and one or more transmitters and / or receivers (TX / RX) 740 that may be coupled to the processors 710.

[0194] TX / RX 740 is for two-way communication. TX / RX 740 may have at least one antenna to facilitate communication. The communication interface may represent any interface required for communication with other network elements. The communication interface may be a hardware-based or software-based interface. For example, the communication interface may be one or more transceivers. One or more transceivers may be coupled to one or more antennas or antenna ports to wirelessly transmit and / or receive communication signals. The antennas or antenna ports may be of the same or different types. The antennas or antenna ports may be located at different positions of the device. One or more transceivers allow the apparatus to communicate with other devices, and the communication may be wired and / or wireless. The transceivers may support one or more radio technologies. For example, one or more transceivers may include a cellular subsystem, a WLAN subsystem, and / or a Bluetooth TM subsystem. One or more transceivers may include circuits such as processors, controllers, radios, sockets, plugs, buffers, etc. to form one or more communication channels to one or more radio frequency units.

[0195] The processor 710 may be of any type suitable for a local technical network, and by way of non-limiting example, may include one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is time-dependent on a clock synchronized with a main processor.

[0196] The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 724, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), and other magnetic storage devices and / or optical storage devices. Examples of volatile memories include, but are not limited to, random access memory (RAM) 722 and other volatile memories that do not persist during power loss.

[0197] The computer program 730 may include computer-executable instructions executed by the associated processor 710. The program 730 may be stored in the ROM 724. The processor 710 may execute any suitable actions and processes by loading the program 730 into the RAM 722.

[0198] Embodiments of the present disclosure may be implemented by means of a program such that the device 700 may execute any process of the present disclosure referred to Figures 1 to 6 in the discussion. Embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0199] In some embodiments, the program 730 may be tangibly embodied in a computer-readable medium, which may be included in the device 700 (such as in the memory 720) or other storage devices accessible by the device 700. The device 700 may load the program 730 from the computer-readable medium into the RAM 722 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Figure 8 An example of a computer-readable medium 800 in the form of a CD or DVD is shown. The program 730 is stored on the computer-readable medium.

[0200] In general, the various embodiments of the present disclosure may be implemented using hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using firmware or software that may be executed by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, by way of non-limiting example, the blocks, devices, systems, techniques, or methods described herein may be implemented using hardware, software, firmware, dedicated circuits or logic, general hardware or a controller or other computing device, or some combination thereof.

[0201] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as the instructions included in a program module, which are executed in a device on a target real or virtual processor to perform the process signaling 200, method 500, or 600 as described above with reference to Figures 1 to 6 the process signaling 200, method 500, or 600 described above. Generally, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules can be combined or split among program modules as needed. The machine-executable instructions of the program module can be executed within a local or distributed device. In a distributed device, the program module can be located in both local and remote storage media.

[0202] The program code for performing the methods of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0203] In the context of the present disclosure, the computer program code or related data can be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0204] The computer-readable media can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatuses, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium will include an electrical connection having one or more wires, a portable computer floppy disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term "non-transitory" as used herein is a limitation on the medium itself (i.e., tangible, rather than a signal), rather than a limitation on the persistence of data storage (e.g., RAM versus ROM).

[0205] Moreover, although the operations are described in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Also, although several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, the various features that are described in the context of a single embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments.

[0206] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the above specific features or acts are disclosed as example forms of implementing the claims.

Claims

1. A terminal device, comprising: One or more transceivers; And One or more processors communicatively coupled to the one or more transceivers, wherein the one or more processors are configured to cause the terminal device to: Receive a quasi - co - located (QCL) source configuration from a network device, wherein the QCL source configuration indicates at least two transmission configuration indicator (TCI) states, the at least two TCI states indicating reference signals from a valid QCL source, the reference signals being used for coherent joint transmission (CJT) of a tracking reference signal (TRS); And Perform QCL attribute estimation on the received TRS based on the QCL source configuration.

2. The terminal device according to claim 1, wherein the QCL source configuration is indicated by a bitmap, and wherein one bit in the bitmap is associated with one of a plurality of potential TCI states.

3. The terminal device according to claim 1 or 2, wherein the QCL attribute estimation includes estimation of one or more of the following: Doppler shift, Doppler spread, average delay, delay spread, or spatial reception parameters.

4. The terminal device according to any one of claims 1 to 3, wherein the terminal device is further caused to: Receive a TRS resource configuration for the QCL attribute estimation of the CJT.

5. The terminal device according to claim 4, wherein the TRS resource is received in a radio resource control (RRC) message and indicates one or more TRS resource sets, and wherein each TRS resource set includes: Four periodic non - zero power channel state information reference signals (NZP CSI - RS) resources in two consecutive time slots, with two periodic NZP CSI - RS resources in each time slot.

6. The terminal device according to claim 4, wherein the TRS resource configuration is received in a downlink control information (DCI) message and indicates either the identity of a NZP CSI - RS resource set or the identity of a NZP CSI - RS resource or both.

7. The terminal device according to any one of claims 1 to 6, wherein the terminal device is further caused to: Send capability information to the network device, wherein the capability information indicates that the terminal device supports CJT TRS transmission and CJT physical downlink shared channel (PDSCH) transmission.

8. The terminal device according to any one of claims 1 to 7, wherein the terminal device is further caused to: Receive a TCI state configuration indicating a plurality of potential TCI states of the terminal device, Wherein each TCI state in the TCI state configuration is associated with one TRS resource in the TRS resource configuration.

9. The terminal device according to any one of claims 1 to 8, wherein the terminal device is further caused to: Receive CSI - RS from the network device; Perform measurements on the CSI - RS; and Report the results of the measurements to the network device.

10. The terminal device according to any one of claims 1 to 9, wherein the terminal device is further caused to: Receive a transmission mode configuration from the network device, wherein the transmission mode configuration indicates a set of transmission modes, including one or more of the following: CJT mode, non - coherent joint transmission (NCJT) mode, or dynamic point selection mode.

11. The terminal device according to claim 10, wherein the terminal device is further caused to: Receive a transmission mode indication from the network device, wherein the transmission mode indication triggers the CJT mode.

12. The terminal device according to any one of claims 1 to 11, wherein the terminal device is further caused to: at the antenna port of the received TRS, receive a demodulation reference signal DMRS and a scheduled CJTPDSCH associated with the DMRS.

13. The terminal device according to claim 12, wherein the received TRS includes: The latest TRS received in a maximum of a predetermined number of time slots before transmitting the scheduled CJTPDSCH.

14. The terminal device according to claim 12, wherein the received TRS includes: Receive and be indicated by the TRS trigger the last triggered TRS in a maximum of a predetermined number of time slots before transmitting the scheduled CJTPDSCH; And / or Wherein the TRS trigger indication is separated from the scheduling command for scheduling the CJT PDSCH.

15. The terminal device according to any one of claims 1 to 14, wherein the terminal device is further caused to: Receive a scheduling command for PDSCH transmission; and Receive the DMRS and the PDSCH based on the QCL attribute estimation.

16. A network device, comprising: One or more transceivers; And One or more processors communicatively coupled to the one or more transceivers, and the one or more processors are configured to cause the network device to: Receive the result of the measurement of the channel state information reference signal CSI-RS set from the terminal device; And Send a quasi-co-location QCL source configuration to the terminal device, wherein the QCL source configuration indicates at least two transmission configuration indication TCI states based on the result of the measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used to track the coherent joint transmission CJT of the reference signal TRS.

17. The network device according to claim 16, wherein the QCL source configuration is indicated by a bitmap, and one bit in the bitmap is associated with one of a plurality of potential TCI states.

18. The network device according to claim 16 or 17, wherein the network device is further caused to: Send a TRS resource configuration for QCL attribute estimation of the CJT to the terminal device.

19. The network device according to claim 18, wherein the QCL attribute estimation includes an estimation of one or more of the following: Doppler frequency shift, Doppler spread, average delay, delay spread, or spatial reception parameter.

20. The network device according to claim 19, wherein the TRS resource is configured to be sent in a Radio Resource Control (RRC) message and indicates one or more TRS resource sets, and each TRS resource set includes: Four periodic non-zero power channel state information reference signal NZP CSI-RS resources in two consecutive time slots, with two periodic NZP CSI-RS resources in each time slot.

21. The network device according to claim 19, wherein the TRS resource configuration is sent in a downlink control information DCI message and indicates one or both of the identity of the NZP CSI-RS resource set or the identity of the NZP CSI-RS resource.

22. The network device according to any one of claims 16 to 21, wherein the network device is further caused to: Receive capability information from the terminal device, where the capability information indicates that the terminal device supports CJT TRS transmission and CJT physical downlink shared channel PDSCH transmission.

23. The network device according to any one of claims 16 to 22, wherein the network device is further caused to: Send a TCI state configuration indicating multiple potential TCI states of the terminal device, where each TCI state in the TCI state configuration is associated with one TRS resource in the TRS resource configuration.

24. The network device according to any one of claims 16 to 23, wherein the network device is further caused to: Send CSI-RS to the terminal device.

25. The network device according to claim 24, wherein the network device is further caused to: Determine one or more CJT parameters based on the result of the received measurement, where the one or more CJT parameters include one or more of the following: the precoder of the CJT, the rank, or the modulation and coding scheme MCS of the CJT.

26. The network device according to any one of claims 16 to 25, wherein the network device is further caused to: Send a transmission mode configuration to the terminal device, where the transmission mode configuration indicates a set of transmission modes, including one or more of the following: CJT mode, non-coherent joint transmission NCJT mode, or dynamic point selection mode.

27. The network device according to claim 26, wherein the network device is further caused to: Send a transmission mode indication to the terminal device, where the transmission mode indication triggers the CJT mode.

28. The network device according to any one of claims 16 to 27, wherein the network device is further caused to: at the antenna port of the transmitted TRS, send a demodulation reference signal DMRS and a scheduled CJTPDSCH associated with the DMRS.

29. The network device according to claim 28, wherein the transmitted TRS includes: The latest TRS sent in at most a predetermined number of time slots before transmitting the scheduled CJTPDSCH.

30. The network device according to claim 28, wherein the transmitted TRS includes: The last triggered TRS sent in at most a predetermined number of time slots before transmitting the scheduled CJTPDSCH and indicated by the TRS trigger, and where the scheduling command is separated from the DCI that triggers the TRS.

31. The network device according to any one of claims 16 to 30, wherein the network device is further caused to: Send a scheduling command for PDSCH transmission; and Send DMRS and PDSCH based on QCL attribute estimation.

32. The network device according to any one of claims 16 to 31, wherein the network device is further caused to: Activate the valid QCL source through any one of a media access control MAC control element CE or a DCI message.

33. A method at a terminal device, comprising: Receive a quasi - co - located (QCL) source configuration from a network device, where the QCL source configuration indicates at least two transmission configuration indication (TCI) states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for coherent joint transmission (CJT) of a tracking reference signal (TRS); And Perform QCL attribute estimation on the received TRS based on the QCL source configuration.

34. A method at a network device, comprising: Receive results of measurements on a channel state information reference signal (CSI - RS) set from a terminal device; And Send a quasi - co - located QCL source configuration to the terminal device, where the QCL source configuration indicates at least two TCI states based on the results of the measurements on the CSI - RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used to track the CJT of the TRS.

35. An apparatus for a terminal device, comprising: Components for receiving a quasi - co - located QCL source configuration from a network device, where the QCL source configuration indicates at least two TCI states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for CJT of a TRS; And Components for performing QCL attribute estimation on the received TRS based on the QCL source configuration.

36. An apparatus for a network device, comprising: Components for receiving results of measurements on a CSI - RS set from a terminal device; And Components for sending a quasi - co - located QCL source configuration to the terminal device, where the QCL source configuration indicates at least two TCI states based on the results of the measurements on the CSI - RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used to track the CJT of the TRS.

37. A terminal device, comprising: At least one processor; And At least one memory including computer program code, where the at least one memory and the computer program code are configured to, together with the at least one processor, cause the terminal device to: Receive a quasi - co - located QCL source configuration from a network device, where the QCL source configuration indicates at least two TCI states, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used for CJT of a TRS; And Perform QCL attribute estimation on the received TRS based on the QCL source configuration.

38. A network device, comprising: At least one processor; And At least one memory including computer program code, where the at least one memory and the computer program code are configured to, together with the at least one processor, cause the terminal device to: Receive results of measurements on a CSI - RS set from a terminal device; And Send a Quasi-Co-Location (QCL) source configuration to the terminal device, where the QCL source configuration indicates at least two Transmission Configuration Indication (TCI) states based on the result of the measurement of the CSI-RS set, and the at least two TCI states indicate reference signals from a valid QCL source, and the reference signals are used to track the Coherent Joint Transmission (CJT) of the Tracking Reference Signal (TRS).

39. A non-transitory computer-readable medium comprising program instructions for causing a device to at least perform the method according to claim 34 or 35.

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