Network node, terminal device, control method, and program for improving accuracy of channel estimation

Abstract

A network node in a wireless communication network including a terminal device, a network node, and another network node different from the network node, the terminal device accepting the provision of a communication service using a plurality of transmission / reception points, and the network node communicating with the terminal device using some of the plurality of transmission / reception points, the other network node communicates with the terminal device using another portion of the plurality of transmission / reception points, the network node receives, from another network node, information relating to a result of measurement of the reception quality in another portion of the plurality of transmission / reception points, of a sounding reference signal (SRS) transmitted from the terminal device at a first transmission power determined by the power at which the SRS is to be received in the portion of the plurality of transmission / reception points, and transmits, on the basis of the information, the SRS transmitted from the terminal device at a second transmission power determined by the power at which the SRS is to be received in the portion of the plurality of transmission / reception points. A second transmission power for the SRS is determined, and a notification for causing the terminal device to transmit the SRS at the second transmission power is transmitted to the terminal device using at least one of some of the plurality of transmission / reception points.

Description

Technical Field

[0001] The present invention relates to a technology for improving the accuracy of channel estimation in wireless communications. Background Art

[0002] As a duplexing method in a cellular communication system, time division duplexing (TDD) is known. In TDD, different time slots in the same frequency channel are allocated for uplink (a link for sending signals from a terminal device to a network node (base station device)) and downlink (a link for sending signals from a network node to a terminal device) communications. In TDD, since the same frequency channel is used in the uplink and downlink, for example, a channel estimation value obtained on the network side based on a sounding reference signal (SRS) of the uplink can be used for communications in the downlink. Summary of the invention

[0003] Problems to be solved by the invention

[0004] In the downlink, signals can be sent from multiple transmission and reception points provided by one or more network nodes toward a terminal device. In order to efficiently perform such downlink signal transmission, it is important to accurately perform channel estimation between each of the multiple transmission and reception points and the multiple antennas of the terminal device.

[0005] Means used to solve problems

[0006] The present invention provides a technology for improving the accuracy of channel estimation between a transmission / reception point and a terminal device.

[0007] A network node involved in one embodiment of the present invention is the network node in a wireless communication network including a terminal device, a network node, and other network nodes different from the network node, the terminal device uses multiple sending and receiving points to receive provision of communication services, the network node uses a part of the multiple sending and receiving points to communicate with the terminal device, and the other network nodes use another part different from the part of the multiple sending and receiving points to communicate with the terminal device, wherein the network node has: a receiving unit, which receives from the other network node information associated with a result of measuring the reception quality in the other part of the multiple sending and receiving points of the sounding reference signal (SRS) sent from the terminal device at a first sending power determined according to the power of the SRS to be received in the part of the multiple sending and receiving points; a determination unit, which determines a second sending power of the SRS based on the information; and a notification unit, which uses at least any one of the part of the multiple sending and receiving points to send a notification to the terminal device for causing the terminal device to send the SRS at the second sending power.

[0008] A network node involved in another embodiment of the present invention is the network node in a wireless communication network including a network node that communicates with a terminal device using a part of a plurality of transmitting and receiving points, and other network nodes that communicate with the terminal device using another part different from the part of the plurality of transmitting and receiving points, wherein the network node has: an acquisition unit that acquires a result of measuring the reception quality of a sounding reference signal (SRS) in the part of the plurality of transmitting and receiving points; and a sending unit that sends to the other network node information associated with the result of measuring the reception quality of the SRS, which is sent from the terminal device in the part of the plurality of transmitting and receiving points and in the other part of the plurality of transmitting and receiving points at a first transmission power determined according to the power of the SRS to be received, and the information is used when determining a second transmission power of the SRS in the other network node.

[0009] A terminal device involved in one embodiment of the present invention is the terminal device in a wireless communication network including a terminal device, a network node and other network nodes different from the network node, the terminal device uses multiple sending and receiving points to receive provision of communication services, the network node uses a part of the multiple sending and receiving points to communicate with the terminal device, and the other network nodes use another part different from the part of the multiple sending and receiving points to communicate with the terminal device, wherein the terminal device has a sending unit, the sending unit sends the sounding reference signal (SRS) for measuring at each of the multiple sending and receiving points at a first sending power determined according to the power of the SRS to be received in the part of the multiple sending and receiving points, and after sending the SRS, when information indicating that the SRS should be sent at a second sending power determined according to the power of the SRS to be received in the other part of the multiple sending and receiving points is received from the network node, the SRS is sent at the second sending power.

[0010] Effects of the Invention

[0011] According to the present invention, it is possible to estimate the channel between the transmission / reception point and the terminal device with high accuracy.

[0012] Other features and advantages of the present invention will become clear from the following description with reference to the accompanying drawings. It should be noted that in the accompanying drawings, the same reference numerals are used for the same or similar components. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0014] Figure 1 This is a diagram showing an example of the configuration of a wireless communication network.

[0015] Figure 2 This is a diagram showing an example of the hardware configuration of the device.

[0016] Figure 3 This is a diagram showing an example of the functional configuration of a network node.

[0017] Figure 4 This is a diagram showing an example of the functional configuration of a terminal device.

[0018] Figure 5 This is a diagram showing an example of the flow of processing performed in a wireless communication network. DETAILED DESCRIPTION

[0019] Hereinafter, the embodiments are described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention involved in the technical solution. In addition, the combination of features described in the embodiments may not all be necessary for the invention. It is also possible to arbitrarily combine two or more of the multiple features described in the embodiments. In addition, the same or identical configurations are marked with the same reference numerals, and repeated descriptions are omitted.

[0020] (Network Structure)

[0021] Figure 1 An example of the configuration of a wireless communication network involved in the present embodiment is shown. The present wireless communication network is configured to include a plurality of transmission and reception points (TRPs) 101 to 102 that are geographically dispersed and a terminal device 111 that communicates with the network via the plurality of transmission and reception points. The transmission and reception points 101 to 102 are each configured to include one or more antennas. In addition, in the present embodiment, the transmission and reception points 101 to 102 can be connected to different network nodes, respectively. That is, the first network node connected to the first transmission and reception point 101 and the second network node connected to the second transmission and reception point 102 cooperate to provide wireless communication services to the terminal device 111. It should be noted that this is an example, and the transmission and reception points 101 to 102 can also be connected to one network node. That is, one network node can be configured to communicate with the terminal device 111 via a plurality of transmission and reception points that are geographically dispersed. It should be noted that the following describes processing performed between independent network nodes when each transmission and reception point is connected to these network nodes, but this processing can be replaced by processing within one network node that has multiple transmission and reception points placed under it.

[0022] The quality of wireless communication service in such a wireless communication system depends on the accuracy of the channel estimation value between the antenna possessed by the terminal device 111 and each antenna included in the multiple transmission and reception points 101 to 102. Here, in this embodiment, if time division duplexing (TDD) is used, it is possible to perform downlink channel estimation by measuring the wireless quality of the sounding reference signal (SRS) transmitted from the terminal device 111 in each antenna of the multiple transmission and reception points. This is because, in TDD, the same frequency channel is used in the downlink in which signals are transmitted from each transmission and reception point to the terminal device 111 and the uplink in which signals are transmitted from the terminal device 111 to each transmission and reception point.

[0023] For example, the SRS is a different sequence for each antenna of the terminal device 111, and is generated using a known sequence in the terminal device 111 and the transmitting and receiving point. That is, for example, when the terminal device 111 has four antennas, different sequences are used in the four antennas to generate the SRS. Then, the generated SRS is transmitted from the corresponding antenna in the same time and frequency resources. In this way, the SRS is multiplexed (code division multiplexed) in the power direction and transmitted using different sequences in the same time and frequency resources. In the transmitting and receiving point, the SRS can be detected using the sequence corresponding to each antenna of the terminal device 111, and the channel estimation between each antenna of the terminal device 111 and the transmitting and receiving point is performed. It should be noted that when the transmitting and receiving point has multiple antennas, channel estimation between each antenna of the terminal device 111 is performed in each of the multiple antennas.

[0024] In addition, the terminal device 111 transmits the SRS using, for example, a first transmission power determined in such a way that the power of the SRS to be received in the transmission and reception point (e.g., transmission and reception point 101) under the network node for communication for control becomes a predetermined value. It should be noted that this is an example, and the first transmission power may also be a predetermined value. In addition, the transmission power used when performing communication for control may also be determined as the first transmission power. In one example, when the setting information of the SRS is sent from the network node, the first transmission power may be specified.

[0025] In this case, for example, when a transmission / reception point (e.g., transmission / reception point 102) under a network node that does not perform control communication is located relatively far from the terminal device 111, it is conceivable that the SRS cannot be received with sufficient power at the transmission / reception point. In such a situation, at the transmission / reception point that cannot receive the SRS with sufficient power, channel estimation cannot be performed with sufficiently high accuracy, and it may be difficult to obtain sufficient communication performance.

[0026] In view of such a situation, in the present embodiment, for example, the following steps are provided: in a part of the transmission and reception points, when the result of the measurement of the SRS transmitted from the terminal device 111 with the above-mentioned first transmission power is that the reception quality such as its reception power is insufficient, the transmission power of the SRS is increased. The above-mentioned first transmission power is set so that the reception power of the SRS in the transmission and reception points under the network node that performs control communication with the terminal device 111 becomes a predetermined value. In contrast, in the transmission and reception points under the other network nodes that do not perform control communication with the terminal device 111, the reception power of the SRS may be significantly lower than the predetermined value. In this case, the other network nodes provide the network node that performs control communication with the terminal device 111 with information for increasing the transmission power of the SRS of the terminal device 111.

[0027] For example, when the receiving power of SRS in the transmitting and receiving point 102 is insufficient, the second network node having the transmitting and receiving point 102 under its control notifies the first network node having the transmitting and receiving point 101 under its control of information associated with the receiving power of SRS while performing control communication with the terminal device 111. Then, the first network node determines the second transmitting power of SRS and notifies the terminal device 111 of the second transmitting power via the transmitting and receiving point 101 under its control so that the receiving power of SRS in the second network becomes sufficient. Thereafter, the terminal device 111 transmits SRS using the second transmitting power. Thus, the terminal device 111 can transmit SRS not only based on the transmitting power of the transmitting and receiving point under the network node performing control communication, but also based on the transmitting power of the transmitting and receiving point other than this. As a result, the transmitting and receiving point under the network node that does not perform control communication can also receive SRS with sufficient power, and the channel estimation accuracy can be sufficiently improved.

[0028] It should be noted that the information associated with the received power of the SRS may be information indicating the change of the transmission power of the SRS, which is generated based on the result of the measurement of the reception quality of the SRS in the transmission and reception point 102 under the second network node. For example, the information indicating the change of the transmission power of the SRS may be information indicating the difference between the target value of the transmission power of the SRS and the actual received power, which indicates that the transmission power of the SRS should be increased. It should be noted that the second network node may also send the transmission power change indication information in a manner of reducing the transmission power of the SRS when the received power of the SRS is improved by the movement of the terminal device 111 or the like. In these cases, the information indicating the change of the transmission power of the SRS may be configured to include information indicating the value of the amount by which the transmission power is changed. It should be noted that the first network node may directly add the value indicated by the information indicating the change of the transmission power of the SRS to the current first transmission power to determine the second transmission power that the terminal device 111 should use in the transmission of the SRS. Then, the first network node may notify the terminal device 111 of a signal indicating that the SRS is transmitted at the second transmission power. However, this is only an example, and the second transmit power may also be determined as a value obtained by adding a value different from the value indicated by the change indication information of the transmit power of the SRS to the first transmit power. For example, the first network node may determine as the second transmit power a value obtained by adding a value smaller than the value indicated by the change indication information of the transmit power of the SRS to the first transmit power. In this way, it is possible to prevent the transmit power of the SRS from becoming too large or too small. In addition, the change indication information of the transmit power of the SRS may be information indicating that the transmit power of the SRS is increased or decreased by a predefined value such as 1 dB. Upon receiving the information, the first network node may send an indication to the terminal device 111 of an increase or decrease of the indicated transmit power of the SRS by a predefined value.

[0029] In addition, the first network node may notify the second network node of the determined second transmission power. As a result, the second network node can identify the transmission power at which the SRS is transmitted, and can therefore accurately estimate, for example, path loss. It should be noted that, in the case where the second network node has determined the approximate path loss by transmitting the SRS at the first transmission power, there is no need to re-notify the second transmission power. In addition, in the case where the transmission power is changed based on the change indication information of the second network node, since the second network node can determine the transmission power of the SRS, the first network node may not notify the second network node of the second transmission power.

[0030] It should be noted that the first network node may also receive information including a value indicating an amount by which the transmit power is changed from the second network node, and transmit an instruction to increase or decrease the transmit power of the SRS by a predefined value according to the value. When the received value is a value for increasing the transmit power, the first network node may notify the terminal device 111 of information indicating that the transmit power of the SRS is increased by a predefined value. In addition, when the received value is a value for decreasing the transmit power, the first network node may notify the terminal device 111 of information indicating that the transmit power of the SRS is decreased by a predefined value. It should be noted that the predefined first value for increasing the transmit power may be the same value as the predefined second value for decreasing the transmit power, or may be a different value. For example, by making the first value greater than the second value, when the transmit power is insufficient, the time until the transmit power becomes sufficient can be shortened, and a situation where the transmit power is greatly insufficient when the transmit power is reduced can be prevented. In addition, by making the second value greater than the first value, a situation where the SRS is transmitted with excessive power can be prevented. It should be noted that a plurality of different values ​​may be predefined as the value for increasing the power, and in addition or in lieu thereof, a plurality of different values ​​may be predefined as the value for decreasing the power. For example, stepwise values ​​such as +3dB, +1dB, -1dB, and -3dB may be defined for transmission power control.

[0031] In addition, the information associated with the received power of the SRS may also be a value representing the result of the measurement of the received quality of the SRS in the transmitting and receiving point under the second network node. For example, the received quality may be expressed by a received signal strength indicator (RSSI), a signal-to-noise ratio (SNR), and the like. When receiving the information on the result of the measurement of the received quality, the first network node may determine the second transmit power in such a manner that the received quality is above a value suitable for channel estimation. For example, the first network node may determine the second transmit power in such a manner that the power of the SRS to be received in the transmitting and receiving point 102 under the second network node is a predetermined value. It should be noted that this is an example, and as described above, the first network node may also determine the second transmit power in such a manner that the transmit power of the SRS increases or decreases by a predefined value.

[0032] In addition, the first network node may determine the second transmission power when the difference between the value of the measurement result indicating the reception quality of the SRS in the transmission and reception point under the control of the own device and the value of the measurement result indicating the reception quality of the SRS in the transmission and reception point under the control of the second network node exceeds a predetermined value. That is, when the second network node can receive the SRS with the same reception quality as the reception quality of the SRS in the first network node, unnecessary transmission power control may not be performed.

[0033] It should be noted that the first network node can be configured to notify the second network node of information associated with the reception power of the SRS as described above, regarding the SRS transmitted from the terminal device with which the second network node is performing control communication. In this way, the network node can have functions in the case of performing control communication with the terminal device and other functions. In addition, in the case where there is a transmission and reception point that cannot receive the SRS with sufficient power among the multiple transmission and reception points used for communication with the terminal device, as described above, the network node can increase the transmission power of the SRS. That is, regardless of whether control communication is being performed, in the case where there is a transmission and reception point that cannot receive the SRS with sufficient quality, the network node can notify the terminal device to increase the transmission power of the SRS. In addition, for example, in the case where the reception quality of the SRS at all the transmission and reception points is sufficient, the network node can notify the terminal device to reduce the transmission power of the SRS.

[0034] It should be noted that, in the above-mentioned configuration example, an example in which the network node connected to the transmitting and receiving point determines the setting of the SRS is described, but the same processing as the above-mentioned processing can be performed by any configuration. For example, each transmitting and receiving point may also have the function of being the above-mentioned network node. In this case, each transmitting and receiving point may also cooperate with other transmitting and receiving points to determine the setting of the transmission power of the SRS to be used in the terminal device as described above. In addition, the setting of the transmission power of the SRS to be used in the terminal device may also be determined in a node higher than the network node. In this case, the measurement results of the reception quality of the SRS in each antenna of each transmitting and receiving point are collected to the upper node, and the upper node can determine the setting of the transmission power of the SRS to be used in the terminal device based on the collected information.

[0035] As described above, by receiving the SRS with sufficient power at all the transmission and reception points used for communication with the terminal device, it is possible to improve the channel estimation accuracy.

[0036] (Device Configuration)

[0037] use Figure 2, an example of the hardware configuration of a network node (such as a base station device) and a terminal device is described. In one example, the network node and the terminal device are configured to include a processor 201, ROM202, RAM203, a storage device 204, and a communication circuit 205. The processor 201 is a computer configured to include one or more processing circuits such as a general-purpose CPU (central processing unit) and an ASIC (application-specific integrated circuit), and performs the overall processing of the device and the above-mentioned processing by reading and executing programs stored in ROM202 and the storage device 204. ROM202 is a read-only memory that stores information such as programs and various parameters related to the processing performed by the network node and the terminal device. RAM203 functions as a workspace when the processor 201 executes the program, and is also a random access memory for storing temporary information. The storage device 204 is, for example, composed of a removable external storage device. The communication circuit 205 is, for example, composed of circuits for wireless communications of 5G and its subsequent standards. It should be noted that in Figure 2 A communication circuit 205 is shown in the figure, but the network node and the terminal device may have multiple communication circuits. For example, the network node and the terminal device may have an antenna shared with the wireless communication circuit for 5G and its subsequent standards. It should be noted that the network node and the terminal device may also have an antenna for 5G and an antenna for its subsequent standards, respectively. In addition, the terminal device may also have a communication circuit for other wireless communication networks such as wireless LAN. It should be noted that the network node and the terminal device may have separate communication circuits 205 for each of the multiple frequency bands that can be used, and may also have a common communication circuit 205 for at least a part of these frequency bands. In addition, the network node may also have a wired communication circuit used when communicating with other network nodes and nodes of the core network. It should be noted that the network node may not have a wireless communication circuit, but may have a wired communication circuit for communicating with a sending and receiving point. That is, it can also be configured so that the sending and receiving point has a wireless communication function, and the network node does not participate in the processing of wireless communication.

[0038] Figure 3 301, a transmission power determination unit 302, a setting notification unit 303, and a reception quality acquisition unit 304 are provided as functions of the network node. Figure 3 In the figure, only the functions that are particularly relevant to this embodiment are shown, and the other various functions that the network node can have are omitted. For example, the network node naturally has other functions that the network nodes of 5G and subsequent standards generally have. In addition, Figure 3 The functional blocks are schematically shown, and each functional block can be implemented in an integrated manner or further refined. Figure 3Each function of the MCU 201 can be realized by, for example, executing a program stored in the ROM 202 or the storage device 204, or by executing predetermined software by a processor in the communication circuit 205. It should be noted that the details of the processing performed by each functional unit are not described here, and only the general functions are summarized.

[0039] As described above, the information exchange unit 301 exchanges information with other network nodes. The information exchange unit 301 operates in a manner that gathers information to the network node connected to the transmission and reception point of the service cell providing the terminal device. For example, the information exchange unit 301 of the network node having the transmission and reception point of the service cell providing the terminal device receives information associated with the result of the measurement of the reception quality of the SRS sent from the terminal device from other network nodes having other transmission and reception points used for communication of the terminal device. Here, the transmission power when the terminal device sends the SRS can be, for example, the first transmission power determined in the network node connected to the transmission and reception point in such a way that the reception quality of the SRS in the transmission and reception point providing the service cell reaches a predetermined value. In addition, the first transmission power can be, for example, the power after the transmission power is increased or decreased according to the instruction of the network node. In addition, the information associated with the result of the measurement of the reception quality of the SRS can be, for example, as described above, change indication information indicating the change of the transmission power of the SRS, and information indicating the value of the reception quality. It should be noted that the information exchange unit 301 can exchange information with other network nodes via the Xn interface and the NG interface.

[0040] The transmission power determination unit 302 determines the second transmission power to be used when the terminal device transmits the SRS based on information associated with the result of the measurement of the reception quality of the SRS obtained from other network nodes in the information exchange unit 301. For example, when receiving the change instruction information of the transmission power of the SRS received in the information exchange unit 301, the second transmission power is determined based on the instruction. In addition, the transmission power determination unit 302 may determine the second transmission power based on the reception quality of the SRS in the transmission and reception point under the other network node received in the information exchange unit 301 so that the reception quality reaches a predetermined value.

[0041] The setting notification unit 303 notifies the terminal device of the setting information so that the SRS is transmitted at the second transmission power determined in the transmission power determination unit 302. The setting notification unit 303 may, for example, send the setting information to the terminal device via a radio resource control (RRC) message. In addition, for example, the setting notification unit 303 may also send the setting information via downlink control information (DCI). According to such a configuration, the network node can easily and quickly change the transmission power of the SRS of the terminal device according to the communication status. In addition, the setting notification unit 303 may also, for example, notify other network nodes of the finally determined second transmission power via the information exchange unit 301.

[0042] The reception quality acquisition unit 304 obtains information on the measurement result of the reception quality when the SRS sent from the terminal device is measured from the transmission and reception point connected to the network node itself. It should be noted that the transmission and reception point can also perform only frequency conversion on the received wireless signal and forward it to the network node. In this case, the reception quality acquisition unit 304 can also measure the SRS based on the transmitted wireless signal to obtain the measurement result of the reception quality of the SRS. It should be noted that the reception quality of the SRS can be obtained, for example, by the size of the channel estimation value (the absolute value of the channel estimation value) or the square value of the channel estimation value in each transmission and reception point. In addition, the reception quality of the SRS can also be expressed by other metrics such as the signal-to-noise ratio. The network node can provide information associated with the measurement result of the reception quality of the SRS to other network nodes through the information exchange unit 301.

[0043] Figure 4 401 and 402. Figure 4 In the figure, only the functions that are particularly relevant to this embodiment are shown, and the illustration of various other functions that the terminal device can have is omitted. For example, the terminal device of course has other functions that terminal devices of 5G and subsequent standards generally have. In addition, Figure 4 The functional blocks are schematically shown, and each functional block can be implemented in an integrated manner or further refined. Figure 4 Each function of the MCU 201 can be realized by, for example, executing a program stored in the ROM 202 or the storage device 204, or by executing predetermined software by a processor in the communication circuit 205. It should be noted that the details of the processing performed by each functional unit are not described here, and only the general functions are summarized.

[0044] The setting receiving unit 401 receives the setting of the transmission power of the SRS from the network node providing the serving cell. The setting of the transmission power of the SRS may be received, for example, through a radio resource control (RRC) message. In addition, for example, the setting receiving unit 401 may also receive information indicating the setting of the transmission power of the SRS through downlink control information (DCI). The SRS transmitting unit 402 sets the transmission power based on the setting information of the transmission power received by the setting receiving unit 401, and transmits the SRS.

[0045] (Processing Flow)

[0046] Next, use Figure 5 , an example of a process flow executed in a wireless communication network is described. It should be noted that the details of the process steps described here are as described above, so only an outline of the process flow is described here.

[0047] First, between the first network node having a transmission and reception point providing a service cell and the terminal device, the specified settings including the transmission power of the SRS are performed in the same manner as in the previous processing. First, the first network node requests the terminal device to send capability information (UE Capability: UE capability) (S501). In response to the request, the terminal device sends the UE capability to the first network node (S502). The UE capability here includes, for example, information on the maximum value of the transmission power that the terminal device 111 can use. Based on the UE capability, the first network node determines the setting information including the setting of the initial transmission power of the SRS, and notifies the terminal device of the setting information (S503). The transmission power of the SRS here can be, for example, a first transmission power determined in such a way that the reception quality (e.g., reception power) of the SRS in the transmission and reception point under the first network node reaches a predetermined value. The setting information including the settings related to the transmission power of the SRS can be notified to the terminal device from the first network node, for example, using RRC signaling. When the terminal device receives the setting of the SRS, it notifies the first network node of a response message indicating successful reception (S504). In this way, the initial SRS setting is completed.

[0048] The terminal device 111 generates an SRS, and transmits the SRS from one or more antennas at the first transmission power notified in S503 (S505). The first network node and the second network node measure the SRS transmitted from each antenna of the terminal device 111 in each antenna of the transmission and reception point to which they are respectively connected (S506). The first network node and the second network node perform channel estimation based on the SRS, and measure the reception quality of the SRS. It should be noted that the measurement result of the reception quality of the SRS may also be obtained by using the result of the channel estimation such as the absolute value of the channel estimation value.

[0049] Here, in the second network node, the measurement result of the reception quality of the SRS is insufficient in the high-precision channel estimation. In this case, in one example, the second network node notifies the first network node providing the serving cell of the change indication information notifying that the setting should be changed (S507). The notification can be performed using, for example, an Xn interface or an NG interface. It should be noted that the second network node can also notify the first network node of the measurement result of the reception quality of the SRS. In addition, the second network node may not notify the first network node of the request to improve the predetermined reception quality, etc. instead of notifying that the setting should be changed. The first network node determines whether the transmission power of the SRS should be changed based on the information notified from the second network node. Here, it is assumed that the first network node determines that the SRS should be transmitted at a second transmission power that increases the transmission power (S508). Then, the first network node notifies the terminal device of the setting information for transmitting the SRS at the second transmission power determined (S509). The notification of the setting information of the SRS here can be performed using an RRC message, or can be performed using other forms of messages such as DCI. It should be noted that the first network node can also notify the second network node of the determined second transmission power (S510). This notification can be performed using, for example, the Xn interface or the NG interface.

[0050] Afterwards, the terminal device transmits the SRS at the second transmission power based on the notified setting information (S511), and the first network node and the second network node use the SRS to perform channel estimation and reception quality measurement (S512). By using such a setting of the transmission power of the SRS, the reception quality of the SRS in the transmission and reception point under the second network node is improved. As a result, the accuracy of the channel estimation between each antenna of the terminal device and the antenna of the transmission and reception point can be improved.

[0051] As described above, in this embodiment, by controlling the transmission power of SRS, the reception quality of SRS in the transmission and reception points of the network can be improved, and the channel estimation accuracy can be improved. Therefore, it is possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Improve resilient infrastructure, promote sustainable industrialization, and seek to expand innovation."

[0052] The present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the present invention.

[0053] This application claims priority based on Japanese patent application No. 2022-141007 filed on September 5, 2022, and all of the contents described therein are cited herein.

Claims

1. A network node, comprising a terminal device, a network node, and another network node different from the network node, wherein the terminal device uses a plurality of transmission and reception points to receive provision of communication services, the network node uses a part of the plurality of transmission and reception points to communicate with the terminal device, and the other network node uses another part different from the part of the plurality of transmission and reception points to communicate with the terminal device, wherein: The network node has: a receiving unit that receives, from the other network node, information associated with a result of a measurement of a reception quality in the other part of the plurality of transmission and reception points of a sounding reference signal (SRS) transmitted from the terminal device at a first transmission power determined according to a power of the SRS to be received in the part of the plurality of transmission and reception points; a determining unit, configured to determine a second transmission power of the SRS based on the information; as well as A notification unit that transmits a notification for causing the terminal device to transmit the SRS at the second transmission power to the terminal device using at least any one of the part of the plurality of transmission and reception points.

2. The network node according to claim 1, wherein: The information is information indicating a change in the transmission power of the SRS from the other network node based on a result of measuring the reception quality of the SRS in the other part of the plurality of transmission and reception points, Upon receiving the information, the determination unit determines the second transmission power according to the change instruction information.

3. The network node according to claim 2, wherein: The determination unit determines the second transmit power such that the second transmit power is higher than the first transmit power when the change instruction information is received.

4. The network node according to claim 1, wherein: The information is information indicating a result of measuring the reception quality of the SRS in the other part of the plurality of transmission and reception points, The determination unit determines the second transmission power based on information of the measurement result so that the power of the SRS to be received in the other part of the plurality of transmission and reception points becomes a predetermined value.

5. The network node according to claim 1, wherein: The notification unit further notifies the other network nodes of the second transmission power.

6. The network node according to claim 1, wherein: The network node also has: an acquisition unit configured to acquire a result of measuring the reception quality of the SRS at the part of the plurality of transmission and reception points; as well as A transmitting unit transmits information associated with a result of measuring the reception quality of the SRS in the part of the plurality of transmission and reception points to the other network node.

7. A network node, comprising a network node for communicating with a terminal device using a part of a plurality of transmission and reception points, and another network node for communicating with the terminal device using another part different from the part of the plurality of transmission and reception points, wherein: The network node has: an acquisition unit that acquires a result of measuring reception quality of a sounding reference signal (SRS) in the part of the plurality of transmission and reception points; as well as A sending unit that sends information associated with a result of measuring the reception quality of the SRS, which is sent from the terminal device in the part of the multiple sending and receiving points at the first sending power determined according to the power of the SRS to be received in the other part of the multiple sending and receiving points, and is used when determining the second sending power of the SRS in the other network node.

8. A terminal device, which is the terminal device in a wireless communication network including a terminal device, a network node, and other network nodes different from the network node, wherein the terminal device uses multiple sending and receiving points to receive provision of communication services, the network node uses a part of the multiple sending and receiving points to communicate with the terminal device, and the other network nodes use another part different from the part of the multiple sending and receiving points to communicate with the terminal device, wherein: The terminal device has a sending unit, which sends the sounding reference signal (SRS) for measuring at each of the multiple sending and receiving points at a first sending power determined according to the power of the SRS to be received in the part of the multiple sending and receiving points, and after sending the SRS, when information indicating that the SRS should be sent at a second sending power determined according to the power of the SRS to be received in the other part of the multiple sending and receiving points is received from the network node, the sending unit sends the SRS at the second sending power.

9. A control method, which is a control method performed by a network node in a wireless communication network including a terminal device, a network node, and other network nodes different from the network node, wherein the terminal device uses multiple sending and receiving points to receive provision of communication services, the network node uses a part of the multiple sending and receiving points to communicate with the terminal device, and the other network nodes use another part different from the part of the multiple sending and receiving points to communicate with the terminal device, wherein: The control method comprises the following steps: receiving, from the other network node, information associated with a result of a measurement of reception quality in the other part of the plurality of transmission and reception points of a sounding reference signal (SRS) transmitted from the terminal device at a first transmission power determined according to the power of the SRS to be received in the part of the plurality of transmission and reception points; Based on the information, determining a second transmission power of the SRS; as well as Using at least any one of the part of the plurality of transmission and reception points, a notification for causing the terminal device to transmit the SRS at the second transmission power is transmitted to the terminal device.

10. A control method, which is performed by a network node in a wireless communication network including a network node that communicates with a terminal device using a part of a plurality of transmission and reception points, and another network node that communicates with the terminal device using another part different from the part of the plurality of transmission and reception points, wherein: The control method comprises the following steps: acquiring a result of measuring reception quality of a sounding reference signal (SRS) in the part of the plurality of transmission and reception points; and Information associated with a result of a measurement of a reception quality of the SRS, which is sent from the terminal device in the part of the multiple transmitting and receiving points at a first transmitting power determined according to a power of the SRS to be received in the other part of the multiple transmitting and receiving points, and is used when determining a second transmitting power of the SRS in the other network node, is sent to the other network node.

11. A control method, which is a control method performed by a terminal device in a wireless communication network including a terminal device, a network node, and other network nodes different from the network node, wherein the terminal device uses multiple sending and receiving points to receive provision of communication services, the network node uses a part of the multiple sending and receiving points to communicate with the terminal device, and the other network nodes use another part different from the part of the multiple sending and receiving points to communicate with the terminal device, wherein: The control method comprises the following steps: transmitting a sounding reference signal (SRS) for measurement at each of the plurality of transmission and reception points at a first transmission power determined according to the power of the SRS to be received at the part of the plurality of transmission and reception points; as well as After sending the SRS, upon receiving information from the network node indicating that the SRS should be sent with a second transmission power determined according to the power at which the SRS is to be received in the other part of the multiple transmission and reception points, the SRS is sent with the second transmission power.

12. A program causing a computer included in a network node to execute the following steps, wherein the network node is the network node in a wireless communication network including a terminal device, a network node, and other network nodes different from the network node, the terminal device uses a plurality of transmission and reception points to receive provision of communication services, the network node uses a part of the plurality of transmission and reception points to communicate with the terminal device, and the other network nodes use another part different from the part of the plurality of transmission and reception points to communicate with the terminal device, wherein: The steps include: receiving, from the other network node, information associated with a result of a measurement of reception quality in the other part of the plurality of transmission and reception points of a sounding reference signal (SRS) transmitted from the terminal device at a first transmission power determined according to the power of the SRS to be received in the part of the plurality of transmission and reception points; Based on the information, determining a second transmission power of the SRS; as well as Using at least any one of the part of the plurality of transmission and reception points, a notification for causing the terminal device to transmit the SRS at the second transmission power is transmitted to the terminal device.

13. A program causing a computer included in a network node to execute the following steps, wherein the network node is the network node in a wireless communication network including a network node that communicates with a terminal device using a part of a plurality of transmission and reception points, and another network node that communicates with the terminal device using another part different from the part of the plurality of transmission and reception points, wherein: The steps include: Acquire a result of measuring reception quality of a sounding reference signal (SRS) in the part of the plurality of transmission and reception points; as well as Information associated with a result of a measurement of a reception quality of the SRS, which is sent from the terminal device in the part of the multiple transmitting and receiving points at a first transmitting power determined according to a power of the SRS to be received in the other part of the multiple transmitting and receiving points, and is used when determining a second transmitting power of the SRS in the other network node, is sent to the other network node.

14. A program causing a computer included in a terminal device to execute the following steps, wherein the terminal device is the terminal device in a wireless communication network including a terminal device, a network node, and other network nodes different from the network node, the terminal device uses a plurality of transmission and reception points to receive provision of communication services, the network node uses a part of the plurality of transmission and reception points to communicate with the terminal device, and the other network nodes use another part different from the part of the plurality of transmission and reception points to communicate with the terminal device, wherein: The steps include: transmitting the sounding reference signal (SRS) for measurement at each of the plurality of transmission and reception points at a first transmission power determined according to the power of the SRS to be received at the part of the plurality of transmission and reception points, After sending the SRS, upon receiving information from the network node indicating that the SRS should be sent with a second transmission power determined according to the power at which the SRS is to be received in the other part of the multiple transmission and reception points, the SRS is sent with the second transmission power.

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