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

Abstract

To improve the accuracy of channel estimation between a transmitting / receiving point and a terminal device.SOLUTION: A network node in a wireless communication network that provides a communication service to a terminal device having a plurality of antennas using a plurality of transmitting / receiving points determines, based on results of measurement of the reception quality of a sounding reference signal (SRS) transmitted from each of the plurality of antennas of the terminal device at the plurality of transmitting / receiving points, SRS settings, which include settings for whether the SRS should be transmitted on a plurality of sets of resources corresponding to mutually different sets of time resources, and notifies the terminal device of the SRS settings using one of the plurality of transmitting / receiving points.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Time Division Duplexing (TDD) is known as a duplexing method in cellular communication systems. In TDD, different time slots in the same frequency channel are assigned to uplink (a link in which a signal is transmitted from a terminal device to a network node (base station device)) and downlink (a link in which a signal is transmitted from a network node to a terminal device) communications. In TDD, the same frequency channel is used for uplink and downlink, so that, for example, a channel estimation value obtained on the network side based on an uplink sounding reference signal (SRS) can be used for downlink communications. Summary of the Invention [Problem to be solved by the invention]

[0003] In the downlink, signals can be transmitted to a single terminal device from multiple transmission / reception points provided by one or more network nodes. To efficiently transmit such downlink signals, it is important to perform highly accurate channel estimation between each of the multiple transmission / reception points and the multiple antennas of the terminal device. [Means for solving the problem]

[0004] The present invention provides a technique for improving the accuracy of channel estimation between a transmitting / receiving point and a terminal device.

[0005] A network node according to one aspect of the present invention is a network node in a wireless communication network that provides communication services to a terminal device having a plurality of antennas using a plurality of transmission / reception points, and includes: a determination means for determining a setting of a sounding reference signal (SRS) including a setting of whether the SRS should be transmitted using a plurality of resource sets corresponding to mutually different time resource sets, based on a result of measurement of reception quality of the SRS transmitted from each of the plurality of antennas of the terminal device at the plurality of transmission / reception points; and a notification means for notifying the terminal device of the setting of the SRS using one of the plurality of transmission / reception points. The SRS configuration includes a configuration indicating that, when the SRS is to be transmitted using the plurality of resource sets, the number of antennas through which the SRS is transmitted in each of the plurality of resource sets is reduced compared to when the SRS is to be transmitted using one resource set. .

[0007] A terminal device according to one aspect of the present invention is a terminal device in a wireless communication network that provides communication services to the terminal device using a plurality of transmission and reception points, and includes: a receiving means for receiving, from a network node of the wireless communication network, a sounding reference signal (SRS) configuration including a setting as to whether the SRS for measurement at each of the plurality of transmission and reception points should be transmitted using a plurality of resource sets corresponding to mutually different sets of time resources; and a transmitting means for transmitting the SRS using the plurality of antennas based on the SRS configuration. The SRS configuration includes a configuration indicating that, when the SRS is to be transmitted using the plurality of resource sets, the number of antennas through which the SRS is transmitted in each of the plurality of resource sets is reduced compared to when the SRS is to be transmitted using one resource set. . [Effects of the Invention]

[0008] According to the present invention, it is possible to improve the accuracy of channel estimation between a transmission / reception point and a terminal device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication network. [Figure 2] FIG. 10 is a diagram illustrating an outline of processing. [Figure 3] FIG. 2 illustrates an example of a hardware configuration of the apparatus. [Figure 4]FIG. 2 is a diagram illustrating an example of a functional configuration of a network node. [Figure 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Figure 6] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication network. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0011] (Network configuration) FIG. 1 shows an example of the configuration of a wireless communication network according to this embodiment. This wireless communication network includes a plurality of transmission / reception points (TRPs) 101-102 that are geographically distributed, and a terminal device 111 that communicates with the network via the plurality of transmission / reception points. Each of the transmission / reception points 101-102 includes one or more antennas. The transmission / reception points 101-102 may be connected to one network node. That is, one network node may be configured to communicate with the terminal device 111 via a plurality of transmission / reception points that are geographically distributed. Note that this is just an example, and the transmission / reception points 101-102 may be connected to different network nodes. In this case, a first network node connected to the first transmission / reception point 101 and a second network node connected to the second transmission / reception point 102 cooperate to provide wireless communication services to the terminal device 111.

[0012] The quality of wireless communication services in such a wireless communication system depends on the accuracy of channel estimation values ​​between the antenna of the terminal device 111 and each antenna included in the multiple transmission / reception points 101 to 102. Here, in this embodiment, if time division duplexing (TDD) is used, channel estimation can be performed by measuring the wireless quality of a sounding reference signal (SRS) transmitted from the terminal device 111 at each antenna of the multiple transmission / reception points. This is because in TDD, the same frequency channel is used in downlinks in which signals are transmitted from each transmission / reception point to the terminal device 111 and in uplinks in which signals are transmitted from the terminal device 111 to each transmission / reception point.

[0013] The SRS is transmitted, for example, in a set of time resources (a collection of time resources consisting of one or more resource elements), with a sequence known to the terminal device 111 and the transmission / reception point allocated to frequency resources at predetermined intervals. At this time, the SRS is transmitted, for example, using a different sequence for each antenna of the terminal device 111. That is, for example, if the terminal device 111 has four antennas, a different sequence of SRS is transmitted from each of the four antennas. In this way, the SRS is multiplexed (code division multiplexed) in the power direction using different sequences in the same time and frequency resources and transmitted. At the transmission / reception point, the SRS is detected using a sequence corresponding to each antenna of the terminal device 111, and channel estimation can be performed between each antenna of the terminal device 111 and the transmission / reception point. Note that if the transmission / reception point has multiple antennas, channel estimation between each antenna of the terminal device 111 is performed for each of the multiple antennas.

[0014] Here, if the total number of antennas in the terminal device 111 is large, many sequences are multiplexed in the power direction, and the power per sequence may not be sufficient. In this case, at a transmission / reception point located far from the terminal device 111, such as transmission / reception point 102 in Fig. 1, for example, it may not be possible to receive the SRS with sufficient power, and the channel estimation accuracy may also be insufficient.

[0015] In view of such circumstances, this embodiment transmits the SRS using a set of multiple resources corresponding to different time resources, for example, when the power of the SRS is insufficient. For example, as shown in FIG. 2(A), assume that the terminal device 111 transmits the SRS using two resource sets in the time direction and a predetermined number of resource elements in the frequency direction. In this state, if it is determined that the power of the SRS is insufficient, for example, at the transmission / reception point 102, another resource set that is not transmitting the SRS in the time direction is used as a resource for transmitting an additional SRS, as shown in FIG. 2(B). Then, the terminal device 111 transmits the SRS corresponding to some antennas using the resources for transmitting the additional SRS, and stops transmitting the SRS corresponding to some antennas using the resources for transmitting the SRS that have been used originally. This reduces the number of sequences multiplexed in simultaneously transmitted SRS, thereby increasing the transmission power per SRS sequence. Increasing the transmission power per SRS sequence improves the power of the SRS received at the transmission / reception point, resulting in highly accurate channel estimation.

[0016] To perform such processing, a network node connected to a transmission / reception point and controlling communications via the transmission / reception point determines an SRS configuration based on measurement results of SRS reception quality (e.g., received power, signal-to-noise ratio, etc.) at multiple transmission / reception points. Here, the SRS configuration includes a setting of whether to distribute and transmit the SRS using multiple resource sets corresponding to mutually different sets of time resources. The network node then notifies the terminal device 111 of the determined SRS configuration. Note that it is possible to assume that the network node is connected to all of multiple transmission / reception points and controls communications at these transmission / reception points. In this case, the network node notifies the terminal device 111 of the SRS configuration and then observes the SRS according to the configuration.

[0017] On the other hand, when a network node is connected to only some of a plurality of transmission / reception points and other network nodes are connected to the other transmission / reception points, the network node notifies not only the terminal device 111 but also the other network nodes of the SRS configuration. This allows the other network nodes to observe the SRS from the terminal device 111 at the above-mentioned other transmission / reception points based on the notified SRS configuration. Furthermore, when determining the SRS configuration, the network node may receive, from the other network nodes, information related to SRS measurement results acquired at the other transmission / reception points connected to the other network nodes. Then, the network node determines the SRS configuration based on the measurement results of the SRS reception quality at the part of the plurality of transmission / reception points to which the network node itself is connected and the information related to the SRS measurement results received from the other network nodes.

[0018] The information related to the SRS measurement result may be, for example, SRS configuration change instruction information based on the measurement result of the SRS reception quality at a transmission / reception point connected to another network node. For example, when the SRS reception quality at a transmission / reception point connected to another network node is below a predetermined level, the other network node may notify the network node of SRS configuration change instruction information for transmitting the SRS using a set of multiple resources corresponding to different times. That is, the other network node may acquire the measurement result of the SRS reception quality at the corresponding transmission / reception point, and when the measurement result value is below a predetermined level, for example, may determine that an additional SRS transmission resource having a different timing from the currently used SRS transmission resource should be used, as shown in FIG. 2(B). The other network node may then generate change instruction information indicating the decision and transmit it to the network node. Furthermore, for example, when the reception quality of an SRS at a transmission / reception point connected to another network node significantly exceeds a predetermined level and the SRS is being transmitted using multiple resource sets corresponding to different times, the other network node may notify the network node of SRS configuration change instruction information, which changes the SRS currently being transmitted using the multiple resource sets to a smaller resource set. When the network node receives this SRS configuration change instruction information, the network node may determine the SRS configuration in accordance with the change instruction information. For example, when the SRS is being transmitted using the resource allocation shown in FIG. 2(A), if the network node receives change instruction information indicating that the SRS should be transmitted using multiple resource sets corresponding to different times, the network node may change the SRS configuration so that the SRS is transmitted using the resource allocation shown in FIG. 2(B). Furthermore, when the SRS is being transmitted using the resource allocation shown in FIG. 2(B), if the network node receives change instruction information indicating that the SRS should be transmitted using a single resource set, the network node may change the SRS configuration so that the SRS is transmitted using the resource allocation shown in FIG. 2(A).

[0019] The change instruction information may be, for example, information instructing that the settings be changed so that the power of the SRS is increased by a predetermined level. For example, assume that the change instruction information notifies the network node from another network node that the received power of the SRS should be improved by 3 dB. In this case, the network node determines the SRS settings so that, for example, the number of SRS sequences transmitted at the same timing is halved and the reduced number of SRS sequences is transmitted at another timing. By halving the number of SRS sequences transmitted at one time, the transmission power per sequence can be doubled. As a result, the received power of the SRS at the transmission / reception points corresponding to the other network nodes can be improved by 3 dB.

[0020] Furthermore, the information related to the SRS measurement result may be information indicating the measurement result of the SRS reception quality at a transmission / reception point connected to another network node. Upon receiving this information, the network node determines the SRS configuration based on at least one of a first measurement result related to the SRS reception quality at a transmission / reception point connected to the own device and a second measurement result related to the SRS reception quality at a transmission / reception point connected to another network node indicated by the received information. For example, if the second measurement result is lower than a predetermined value, the network node may determine the SRS configuration so as to reduce the number of SRS sequences transmitted at one time, as shown in FIG. 2(B). Furthermore, if the difference between the first measurement result and the second measurement result (the absolute value of the difference) exceeds a predetermined value, the network node may determine the SRS configuration so as to reduce the number of SRS sequences transmitted at one time. The predetermined value may be, for example, 3 dB, 6 dB, 10 dB, etc.

[0021] The terminal device 111 transmits SRSs of sequences associated with the designated radio resources in accordance with the SRS configuration determined as described above. Here, it is assumed that the terminal device 111 has a total of four antennas. In this case, for example, when an SRS configuration is used in a resource set such as that shown in FIG. 2(A) to transmit SRSs of a total of four sequences corresponding to the respective antennas, the terminal device 111 generates SRSs corresponding to the respective antennas using the four sequences in accordance with the configuration, and transmits the SRSs from the corresponding antennas using common frequency and time resources. Thereafter, it is assumed that an SRS configuration is performed such that SRSs corresponding to two antennas are transmitted using multiple resource sets with different timings, as shown in FIG. 2(B), for example. In this case, the terminal device 111 transmits SRSs generated using two sequences corresponding to two antennas from the corresponding antennas in the resource set with earlier timing in accordance with the configuration. Furthermore, the terminal device 111 transmits SRSs generated using two sequences corresponding to the remaining two antennas from the corresponding antennas in the resource set with later timing.

[0022] In this way, by expanding the resource settings for transmitting SRS and distributing the transmission timing of SRS based on some sequences so that it differs from the transmission timing of SRS based on other sequences, it is possible to improve the reception quality of SRS at transmission and reception points in the network and improve the accuracy of channel estimation.

[0023] In the above configuration example, an example was described in which a network node connected to a transmission / reception point determines the SRS settings. However, processing similar to the above can be performed in any configuration. For example, each transmission / reception point may have the function of the above-described network node. In this case, each transmission / reception point may cooperate with other transmission / reception points to determine the SRS settings to be used in the terminal device as described above. Also, a node higher than the network node may determine the SRS settings to be used in the terminal device. In this case, measurement results of the SRS reception quality at each antenna of each transmission / reception point are aggregated in the higher node, and the higher node may determine the SRS settings to be used in the terminal device based on the aggregated information. In the above example, an example of processing was described in which four antennas are divided into two groups each, and the transmission timing of the corresponding SRS is different. However, this is not limited to this. For example, the four antennas may be grouped into one antenna and three antennas, or into three or more groups, such as one antenna, one antenna, and two antennas, and the SRS settings may be determined so that the SRS corresponding to the antennas belonging to each group is transmitted at different timings. In addition, in the above-described embodiment, a case where a plurality of transmission and reception points are used has been described, but the above-described processing may be performed to improve the accuracy of channel estimation at one transmission and reception point. In this way, the above-described processing may be performed in various modified forms. Furthermore, the above-described processing may be used in any combination.

[0024] (Device configuration) Using FIG. 3, an example of the hardware configuration of a network node (e.g., a base station device) and a terminal device will be described. In one example, the network node and the terminal device include a processor 301, a ROM 302, a RAM 303, a storage device 304, and a communication circuit 305. The processor 301 is a computer including one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and performs overall processing of the device and each of the above-mentioned processes by reading and executing programs stored in the ROM 302 or the storage device 304. The ROM 302 is a read-only memory that stores information such as programs and various parameters related to the processes executed by the network node and the terminal device. The RAM 303 functions as a workspace when the processor 301 executes a program and is a random access memory that stores temporary information. The storage device 304 is, for example, a removable external storage device. The communication circuit 305 is, for example, a circuit for wireless communication of 5G or its successor standards. Although FIG. 3 illustrates one communication circuit 305, the network node and the terminal device may have multiple communication circuits. For example, the network node and the terminal device may have a common antenna for wireless communication circuits for 5G and its successor standards. The network node and the terminal device may have separate antennas for 5G and its successor standards. The terminal device may also have a communication circuit for other wireless communication networks, such as a wireless LAN. The network node and the terminal device may have separate communication circuits 305 for each of multiple available frequency bands, or may have a common communication circuit 305 for at least some of these frequency bands. The network node may also have a wired communication circuit used when communicating with other network nodes or nodes of the core network. The network node may not have a wireless communication circuit, but may have a wired communication circuit with a transmission / reception point. In other words, the transmission / reception point may have wireless communication functionality, and the network node may be configured not to be involved in wireless communication processing.

[0025] FIG. 4 shows an example of the functional configuration of a network node. The network node has, as its functions, for example, a reception quality acquisition unit 401, an SRS setting determination unit 402, a setting notification unit 403, and an information exchange unit 404. Note that FIG. 4 only shows functions particularly related to this embodiment, and various other functions that the network node may have are omitted from the illustration. For example, the network node naturally has other functions that network nodes of 5G and its successor standards generally have. Also, the functional blocks in FIG. 4 are shown schematically, and the respective functional blocks may be realized by being integrated together or may be further subdivided. Also, each function in FIG. 4 may be realized, for example, by the processor 301 executing a program stored in the ROM 302 or the storage device 304, or may be realized, for example, by a processor inside the communication circuit 305 executing predetermined software. Note that the details of the processing performed by each functional unit will not be described here, and only their general functions will be outlined.

[0026] The reception quality acquisition unit 401 acquires, from a transmission / reception point connected to the network node itself, information on the measurement result of reception quality when an SRS transmitted from a terminal device is measured. Note that the transmission / reception point may, for example, perform only frequency conversion on the received radio signal and forward it to the network node. In this case, the reception quality acquisition unit 401 may measure the SRS based on the forwarded radio signal and acquire the measurement result of the SRS reception quality. Note that the SRS reception quality may be acquired, for example, as the magnitude of the channel estimate value (absolute value of the channel estimate value) or the square value of the channel estimate value at each transmission / reception point. The SRS reception quality may also be expressed by other metrics, such as the signal-to-noise ratio. If necessary, the network node may provide information indicating the measurement result of the SRS reception quality to other network nodes via the information exchange unit 404.

[0027] The SRS setting determination unit 402 determines the SRS setting to be used by the terminal device based on the SRS reception quality acquired by the reception quality acquisition unit 401. For example, if the SRS reception quality acquired by the reception quality acquisition unit 401 is below a predetermined level, the SRS setting determination unit 402 may determine the setting to reduce the number of SRS sequences to be transmitted at one time and increase the transmission power per SRS sequence. Furthermore, if the SRS reception quality acquired by the reception quality acquisition unit 401 is sufficiently above a predetermined level, the SRS setting determination unit 402 may determine the setting to increase the number of SRS sequences to be transmitted at one time and reduce the radio resources on which the SRS is transmitted. Note that the SRS setting determination unit 402 specifies a sequence to be used to generate an SRS for each antenna included in the terminal device 111. Note that while sequences corresponding to SRSs transmitted simultaneously must be different from each other, sequences corresponding to SRSs transmitted at different times may be the same. Furthermore, the SRS configuration determiner 402 may acquire a second measurement result of the SRS reception quality at a transmission / reception point corresponding to another network node via the information exchanger 404, and determine the SRS configuration based on the first measurement result of the reception quality acquired by the reception quality acquirer 401 and the received second measurement result. In one example, when the difference between the first measurement result and the second measurement result exceeds a predetermined value, the SRS configuration determiner 402 may determine an SRS configuration such as reducing the number of SRS sequences to be transmitted at one time in order to improve the reception quality of the SRS with lower reception quality. Furthermore, the SRS configuration determiner 402 may determine, for example, to reduce the number of SRS sequences to be transmitted at one time based on the measurement result of the reception quality acquired by the reception quality acquirer 401, and generate change instruction information indicating the decision. Furthermore, the SRS configuration determiner 402 may generate change instruction information including information indicating how much the reception quality should be improved based on the measurement result of the reception quality acquired by the reception quality acquirer 401. The change instruction information can then be transmitted by the information exchange unit 404 to other network nodes.

[0028] The setting notification unit 403 notifies the terminal device of the SRS setting determined by the SRS setting determination unit 402. The setting notification unit 403 may transmit the SRS setting to the terminal device, for example, by a radio resource control (RRC) message. Alternatively, for example, the setting notification unit 403 may transmit multiple SRS settings to the terminal device in advance by an RRC message, and then transmit information specifying which of the multiple SRS settings to use by downlink control information (DCI). With this configuration, the network node can easily and quickly cause the terminal device to change the SRS setting depending on the communication situation. Furthermore, the setting notification unit 403 may notify other network nodes of the finally determined SRS setting, for example, via the information exchange unit 404.

[0029] The information exchange unit 404 exchanges information with other network nodes as described above. Note that information from the information exchange unit 404 is aggregated in a network node connected to a transmission / reception point that provides a serving cell for the terminal device. The network node where the information is aggregated then makes a final decision on the SRS configuration and notifies the terminal device and other network nodes of the decided SRS configuration. Note that the information exchange unit 404 can exchange information with other network nodes via an Xn interface or an NG interface.

[0030] FIG. 5 shows an example of the functional configuration of a terminal device. The terminal device has, for example, a setting receiving unit 501 and an SRS transmitting unit 502 as its functions. Note that FIG. 5 only shows functions particularly related to this embodiment, and various other functions that the terminal device may have are omitted from the illustration. For example, the terminal device naturally has other functions that terminal devices of 5G and its successor standards generally have. Also, the functional blocks in FIG. 5 are shown schematically, and each functional block may be realized by being integrated or further subdivided. Also, each function in FIG. 5 may be realized, for example, by the processor 301 executing a program stored in the ROM 302 or the storage device 304, or may be realized by a processor within the communication circuit 305 executing predetermined software. Note that the details of the processing performed by each functional unit will not be described here, and only their general functions will be outlined.

[0031] The configuration receiver 501 receives an SRS configuration from a network node that provides a serving cell. This SRS configuration can be received, for example, by a radio resource control (RRC) message. Alternatively, for example, the configuration receiver 501 may receive multiple SRS configurations in advance by an RRC message and receive information specifying which of the multiple SRS configurations to use by downlink control information (DCI). The SRS transmitter 502 transmits the SRS using the configuration received by the configuration receiver 501.

[0032] (Processing flow) Next, an example of the flow of processing executed in a wireless communication network will be described with reference to Fig. 6. Details of the processing steps described here have been described above, so only an outline of the processing flow will be described here. Here, a case will be described in which two network nodes (network node A, network node B) correspond to different transmission and reception points. Also, it is assumed here that network node A provides a serving cell.

[0033] First, SRS is configured between network node A and a terminal device in the same manner as in conventional processing. First, network node A requests the terminal device to transmit capability information (UE Capability) (S601). In response to this request, the terminal device transmits the UE Capability to network node A (S602). Here, the UE Capability includes, for example, information on the number of antennas the terminal device 111 has. In one example, the terminal device 111 notifies the network node A that it has four antennas. Based on this UE Capability, the network node A determines an initial SRS configuration and notifies the terminal device (S603). Here, the SRS configuration is assumed to be performed such that the corresponding SRS is transmitted from each of the four antennas that the terminal device 111 has at the same timing, as shown in FIG. 2(A). Furthermore, the SRS configuration can be notified from the network node A to the terminal device, for example, using RRC signaling. When the terminal device receives this SRS setting, it notifies network node A of a response message indicating that reception was successful (S604), thereby completing the initial SRS setting.

[0034] The terminal device 111 generates an SRS corresponding to each antenna and transmits the SRS from the corresponding antenna using the same set of frequency and time resources according to the settings notified in S603 (S605). Network node A and network node B measure the SRS transmitted from each antenna of the terminal device 111 at each antenna of the transmission / reception point connected to them (S606). Network node A and network node B perform channel estimation based on this SRS and measure the reception quality of the SRS. Note that the measurement result of the SRS reception quality may be obtained by utilizing the result of channel estimation, such as the absolute value of the channel estimation value.

[0035] Here, it is assumed that the measurement result of the SRS reception quality in network node B is insufficient for high-accuracy channel estimation. In this case, in one example, network node B notifies network node A, which provides the serving cell, of change instruction information notifying that the setting should be changed (S607). This notification can be performed, for example, using the Xn interface or the NG interface. Note that network node B may notify network node A of the measurement result of the SRS reception quality, and network node A may determine whether or not to change the SRS setting. Alternatively, network node B may notify network node A that an improvement in reception quality of, for example, 3 dB is required, rather than notifying that the setting should be changed. Network node A determines whether or not to change the SRS setting based on the SRS reception quality acquired by its own device and information notified by network node B. Here, network node A may decide to reduce the number of SRS sequences transmitted at one time and to use the setting as shown in FIG. 2(B) (S608). Then, network node A notifies the terminal device of the determined SRS setting (S609). The notification of the SRS configuration here may be performed using an RRC message or another type of message such as DCI. Network node A also notifies network node B of the determined SRS configuration (S610). This notification may be performed using, for example, the Xn interface or the NG interface.

[0036] Thereafter, the terminal device transmits SRS corresponding to some of the antennas using the notified SRS configuration (S611), and network node A and network node B use this SRS to perform channel estimation and measure reception quality (S612). Furthermore, the terminal device transmits SRS corresponding to some of the remaining antennas that did not transmit SRS at S611 using the notified SRS configuration (S613), and network node A and network node B use this SRS to perform channel estimation and measure reception quality (S614). By using such SRS configuration, the transmission power per sequence increases, and therefore the reception quality of the SRS at the transmission and reception points improves. This makes it possible to improve the accuracy of channel estimation between each antenna of the terminal device and the antennas at the transmission and reception points.

[0037] As described above, in this embodiment, the configuration of resources for transmitting SRS is expanded, and the transmission timing of SRS based on some sequences is distributed so that it differs from the transmission timing of SRS based on other sequences. This improves the reception quality of SRS at transmission and reception points in the network, and improves the accuracy of channel estimation. This makes it possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "Build resilient infrastructure, promote sustainable industrialization, and foster innovation."

[0038] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. A network node in a wireless communication network that provides communication services to a terminal device having a plurality of antennas using a plurality of transmission and reception points, A determination means for determining a setting of a sounding reference signal (SRS), including a setting of whether the SRS should be transmitted in a plurality of resource sets corresponding to mutually different time resource sets, based on a result of measuring reception quality of the SRS transmitted from each of the plurality of antennas of the terminal device at the plurality of transmission and reception points; a notification means for notifying the terminal device of the setting of the SRS using one of the plurality of transmission and reception points; and The SRS configuration includes a configuration indicating that, when the SRS is to be transmitted on the plurality of resource sets, the number of antennas from which the SRS is transmitted in each of the plurality of resource sets is reduced compared to when the SRS is to be transmitted on one resource set.

2. the network node communicates with the terminal device using some of the plurality of transmission and reception points; another network node different from the network node communicates with the terminal device using another part different from the part of the plurality of transmission / reception points; The network node an acquisition means for acquiring a result of measurement of reception quality of the SRS at the part of the plurality of transmission and reception points; receiving means for receiving information relating to a result of measurement of reception quality of the SRS at the other part of the plurality of transmission and reception points from the other network node; and The determination means determines the setting of the SRS based on at least one of a result of measurement of reception quality of the SRS at the part of the plurality of transmission and reception points and the information.

2. The network node according to claim 1, wherein:

3. the information is instruction information for changing the setting of the SRS from the other network node based on a result of measuring reception quality of the SRS at the other part of the plurality of transmission and reception points, The determining means, when receiving the information, determines the setting of the SRS in accordance with the change instruction information.

3. A network node according to claim 2.

4. 4. The network node according to claim 3, wherein, when the determination means receives the change instruction information while the SRS for measuring the reception quality of the SRS at the part of the plurality of transmission / reception points and the SRS for measuring the reception quality of the SRS at the other part of the plurality of transmission / reception points are being transmitted in the same time resource, the determination means determines the configuration of the SRS so that the SRS corresponding to the part of the plurality of antennas of the terminal device is transmitted in a different time resource from the SRS at the other part of the plurality of antennas.

5. the information indicating a result of measurement of reception quality of the SRS at the other part of the plurality of transmission and reception points, the determining means determines the setting of the SRS based on a first result of measuring the reception quality of the SRS at the part of the plurality of transmission and reception points and a second result of measuring the reception quality of the SRS at the other part of the plurality of transmission and reception points.

3. A network node according to claim 2.

6. 6. The network node according to claim 5, wherein, when a difference between the first result and the second result exceeds a predetermined value, the determining means determines the configuration of the SRS such that the SRS corresponding to a part of the plurality of antennas of the terminal device is transmitted in a different time resource from the SRS for another part of the plurality of antennas.

7. the network node communicates with the terminal device using some of the plurality of transmission and reception points; another network node different from the network node communicates with the terminal device using another part different from the part of the plurality of transmission / reception points; The network node an acquisition means for acquiring a result of measurement of reception quality of the SRS at the part of the plurality of transmission and reception points; a transmitting means for transmitting information relating to a result of measuring the reception quality of the SRS at the part of the plurality of transmission and reception points to the other network node; and The determination means determines, based on a result of measuring the reception quality of the SRS at the part of the plurality of transmission and reception points, that the SRS corresponding to the part of the plurality of antennas of the terminal device should be transmitted in a time resource different from that of the SRS at the other part of the plurality of antennas; The transmitting means transmits, as the information, change instruction information instructing the other network node of the result of the determination by the determining means.

2. The network node according to claim 1 .

8. A terminal device in a wireless communication network that provides communication services to the terminal device using a plurality of transmission and reception points, A plurality of antennas; receiving means for receiving a sounding reference signal (SRS) configuration from a network node of the wireless communication network, the SRS configuration including a configuration as to whether the SRS for measurements at each of the plurality of transmission and reception points should be transmitted on a plurality of resource sets corresponding to mutually different sets of time resources; a transmitting means for transmitting the SRS using the plurality of antennas based on the setting of the SRS; and The terminal device is characterized in that the SRS configuration includes a configuration indicating that when the SRS is to be transmitted in the set of multiple resources, the number of antennas from which the SRS is transmitted in each of the sets of multiple resources is reduced compared to when the SRS is to be transmitted in one set of resources.

9. 1. A control method executed by a network node in a wireless communication network that provides communication services to a terminal device having a plurality of antennas using a plurality of transmission and reception points, comprising: determining a setting of a sounding reference signal (SRS) including a setting of whether the SRS should be transmitted in a plurality of resource sets corresponding to mutually different sets of time resources based on a result of measuring reception quality of the SRS transmitted from each of the plurality of antennas of the terminal device at the plurality of transmission and reception points; notifying the terminal device of the setting of the SRS using one of the plurality of transmission and reception points; Including, A control method characterized in that the SRS configuration includes a configuration indicating that when the SRS is to be transmitted in the set of multiple resources, the number of antennas from which the SRS is transmitted in each of the set of multiple resources is reduced compared to when the SRS is to be transmitted in one set of resources.

10. A control method executed by a terminal device in a wireless communication network that provides communication services to a terminal device having a plurality of antennas using a plurality of transmission and reception points, comprising: receiving, from a network node of the wireless communication network, a configuration of a sounding reference signal (SRS) for measurements at each of the plurality of transmission and reception points, the SRS including a configuration of whether the SRS should be transmitted on a plurality of resource sets corresponding to mutually different sets of time resources; Transmitting the SRS using the plurality of antennas based on the configuration of the SRS; Including, A control method characterized in that the SRS configuration includes a configuration indicating that when the SRS is to be transmitted in the set of multiple resources, the number of antennas from which the SRS is transmitted in each of the set of multiple resources is reduced compared to when the SRS is to be transmitted in one set of resources.

11. A computer provided in a network node in a wireless communication network that provides communication services to a terminal device having a plurality of antennas using a plurality of transmission and reception points, determining a configuration of a sounding reference signal (SRS) transmitted from each of the plurality of antennas of the terminal device at the plurality of transmission and reception points, the configuration including a configuration of whether the SRS should be transmitted in a plurality of resource sets corresponding to mutually different time resource sets; Using any one of the plurality of transmission / reception points, notify the terminal device of the setting of the SRS. A program for: The program, characterized in that the SRS settings include settings indicating that when the SRS is to be transmitted in the set of multiple resources, the number of antennas from which the SRS is transmitted in each of the set of multiple resources is reduced compared to when the SRS is to be transmitted in one set of resources.

12. A computer provided in a terminal device in a wireless communication network that provides communication services to the terminal device having a plurality of antennas using a plurality of transmission and reception points, receiving, from a network node of the wireless communication network, a configuration of a sounding reference signal (SRS) for measurements at each of the plurality of transmission and reception points, the configuration including a configuration of whether the SRS should be transmitted on a plurality of resource sets corresponding to mutually different sets of time resources; transmitting the SRS using the plurality of antennas based on the setting of the SRS; A program for: The program, characterized in that the SRS settings include settings indicating that when the SRS is to be transmitted in the set of multiple resources, the number of antennas from which the SRS is transmitted in each of the set of multiple resources is reduced compared to when the SRS is to be transmitted in one set of resources.

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