JP2022088164A - Base station device, terminal device, communication method, and program in communication system that forms beam on downlink and communicates - Google Patents

Abstract

To appropriately select and use a transmission method using a plurality of antennas according to a situation.SOLUTION: A base station device including a plurality of antennas transmits a predetermined signal for estimation of a transmission path by a terminal device from each of the plurality of antennas, over an entire available frequency band, receives, from the terminal device, information about a precoding matrix which the base station device should use for each of a plurality of frequency domains, forms a beam based on a frequency resource that should be used for signal transmission to the terminal device and notified information, and transmits a signal to the terminal device. Each of the plurality of frequency domains is a part of the available frequency band.SELECTED DRAWING: Figure 5

Description

The present invention relates to a communication system in which a plurality of antennas are used to form a beam on a downlink and communicate with each other.

In the field of wireless communication technology, a technique of effectively utilizing spatial resources by using a plurality of antennas is known in order to improve the throughput and expand the communication capacity. This technique includes, for example, multi-input multi-output (MIMO) and antenna diversity. In the cellular communication system, the terminal device can observe the CSI-RS (Channel State Information Reference Signal) transmitted from the base station device and estimate the state of the downlink transmission line based on the CSI-RS. Then, the terminal device specifies one of a plurality of PMI (Precoding Matrix Indicator) values corresponding to each of the plurality of antenna weight patterns prepared in advance based on the estimation result, and the specified PMI value. Is notified to the base station device. The base station device can form a beam with the antenna weight corresponding to the notified PMI and communicate with the terminal device. In the technique using PMI, the terminal device is made to estimate the transmission line, a roughly suitable beam is selected based on the transmission line estimation value, and only the selection result is fed back, so that the beam is set with a small amount of feedback. be able to.

CSI-RS is transmitted only in certain frequency domains that are part of the available frequency band. Therefore, the state of the transmission line measured by the terminal device is also related to the specific frequency region, and may not be suitable for other frequency regions in the usable frequency band. In such a case, the beam corresponding to the PMI notified from the terminal device may not be suitable for the frequency resource when the signal is transmitted from the base station device to the terminal device.

The present invention provides techniques that make it possible to form an appropriate beam for the frequency resources used for communication.

The base station apparatus according to one aspect of the present invention has a plurality of antennas and communication means, and the communication means has a transmission path from each of the plurality of antennas to a transmission path by the terminal device over the entire usable frequency band. A predetermined signal for estimation is transmitted, information about a precoding matrix to be used by the base station apparatus is received from the terminal apparatus for each of the plurality of frequency regions, and each of the plurality of frequency regions receives information about the precoding matrix to be used. A beam is formed based on the frequency resource which is a part of the available frequency band and should be used for communication with the terminal device and the received information, and a signal is transmitted to the terminal device. It is characterized by being composed.

Further, the terminal device according to one aspect of the present invention transmits a predetermined signal for estimating a transmission line by the terminal device transmitted from each of a plurality of antennas of the base station device over the entire usable frequency band. A receiving means for receiving, an estimating means for estimating the state of the transmission line for each of the plurality of frequency regions based on the predetermined signal, and the estimation means for estimating the state of the transmission line, and the plurality of frequency regions based on the estimated state of the transmission line. A determination means for determining a precoding matrix to be used by the base station apparatus in each, and a transmission means for transmitting information regarding a precoding matrix to be used in each of the determined plurality of frequency regions to the base station apparatus. , Each of the plurality of frequency regions is a part of the usable frequency band.

According to the present invention, it is possible to form an appropriate beam for the frequency resource used for communication.

It is a figure which shows the configuration example of a wireless communication system. It is a figure which shows the hardware configuration example of a base station apparatus and a terminal apparatus. It is a figure which shows the functional composition example of a base station apparatus. It is a figure which shows the functional configuration example of a terminal apparatus. It is a figure which shows the example of the flow of the process executed by a base station apparatus. It is a figure which shows the example of the flow of the process which a terminal apparatus executes.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. In addition, the same or similar configuration will be given the same reference number, and duplicated explanations will be omitted.

(System configuration)
FIG. 1 shows a configuration example of a wireless communication system according to the present embodiment. The wireless communication system is, for example, a long-term evolution (LTE) or fifth generation (5G) cellular communication system, and includes a base station device 101 having a plurality of antennas and a terminal device 102 having one or more antennas. Consists of.

In the present wireless communication system, the base station apparatus can form a beam based on an estimated value of the state of the transmission path to and from the terminal apparatus, and transmit a wireless signal (wireless frame) to the terminal apparatus. Throughout the present embodiment and the scope of the attached patent claim, the state of the transmission path between the base station device and the terminal device is defined as each of the plurality of antennas of the base station device and one or more of the terminal devices. The state of the transmission line between each of the antennas of the above is shown. For example, when the base station device has N antennas and the terminal device has M antennas, the state of N × M transmission lines is estimated. For example, the base station apparatus multiplies the antenna weight in each of the plurality of antennas calculated based on the estimated value of the state of the transmission line by the radio frame to be transmitted, and transmits the antenna weights from the plurality of antennas in parallel.

The base station device can transmit a plurality of data streams to the terminal device in parallel, for example, when the terminal device has a plurality of antennas. That is, it is possible to use MIMO (Multiple-Input Multiple-Output) technology in which both the base station device and the terminal device use a plurality of antennas to transmit and receive a plurality of streams. In this technique, a plurality of data streams may be spatially multiplexed and transmitted in the same frequency band and time. In this case, for example, by multiplying the antenna weight matrix (precoding matrix) of the number of transmitting antennas × the number of receiving antennas by a vector indicating each data stream, a vector of the data stream to be transmitted by each transmitting antenna is generated. Then, each of the plurality of antennas of the base station device (transmitting side) transmits the corresponding element of the vector. According to this, in one example, it is possible to extract a plurality of transmitted streams with high quality from the signals received by each antenna of the terminal device (reception side).

As a method for the base station device to form a beam and transmit a signal, a plurality of precoding matrix candidates that can be used by the base station device are prepared in advance, and any of the candidates is used by the base station device. A method is known in which a terminal device determines whether or not it should be done. In this method, the terminal device estimates the state of the transmission line based on the CSI-RS (Channel State Information Reference Signal) received from the base station device, and emits a beam suitable for the estimated state of the transmission line in advance. Select from the prepared precoding matrices. Then, the terminal device notifies the base station device of the information for identifying the selected beam as a PMI (Precoding Matrix Indicator). The base station apparatus identifies the precoding matrix to be used based on the PMI, forms a beam using the identified precoding matrix, and transmits a signal.

However, as mentioned above, CSI-RS is transmitted only in some frequency domains of the available frequency band. Therefore, the terminal device can appropriately estimate the transmission line in a part of the frequency domain and select the PMI. On the other hand, the state of the transmission line may be different for other frequency regions. For this reason, for example, the beam specified by the PMI may not be appropriate for the frequency resource that the base station device determines to use when transmitting a signal such as user data to the terminal device. In this embodiment, in view of such circumstances, the base station apparatus transmits a predetermined signal such as SRS (Sounding Reference Signal) over the entire available frequency band. Note that SRS is an example and may be another signal whose transmission path can be estimated. Here, since the base station apparatus has a constant power density at the time of signal transmission per a certain frequency range, it is possible to transmit a predetermined signal with sufficient power over the entire usable frequency band. Therefore, even a terminal device at a position sufficiently distant from the base station device can receive this predetermined signal with sufficient power.

The terminal device receives this predetermined signal at each of the one or more antennas, and estimates the state of the transmission line for each of the plurality of frequency domains based on the predetermined signal. The plurality of frequency domains are each a part of the frequency band that can be used in the wireless communication system. It should be noted that the plurality of frequency domains may be configured so as not to overlap each other, for example, by dividing the usable frequency band, or a frequency range in which two or more frequency domains overlap each other in a part thereof. May be configured to include. However, a plurality of frequency domains are set so that any one frequency domain among the plurality of frequency domains includes the other frequency domain or is not included in the other frequency domain. In addition, each frequency domain may be set so as to cover the entire available frequency band by the plurality of frequency domains, or a plurality of frequency domains (for example, in a small range) may be set to a plurality of frequency domains. Each frequency domain may be set so that it is not included. The terminal device selects the precoding matrix to be used by the base station device from the candidates of the precoding matrix available to the base station device based on the estimated transmission line state for each of the multiple frequency domains. do. Then, the terminal device notifies the base station device of the PMI corresponding to the selected precoding matrix for each of the plurality of frequency domains. At the time of this notification, for example, a message directly describing the PMI value in each frequency domain may be transmitted, and the reference PMI value and the difference value of the PMI in each frequency domain are included. A message may be sent. In one example, the reference PMI value is a PMI value suitable for the entire available frequency band, and whether the PMI difference value in each frequency domain is the same as or different from the PMI value. It can be information indicating. Further, the reference PMI value may be a PMI value in any frequency region. According to this, the base station apparatus can specify, for example, a frequency domain in which a PMI common to the reference PMI can be used, and allocate resources so as to transmit a signal to the terminal apparatus in that frequency domain. ..

The base station device transmits information indicating that a predetermined signal such as SRS for enabling the terminal device to estimate the transmission path is transmitted (indicating whether or not the predetermined signal is transmitted). May be good. In one example, the base station device may individually transmit the setting information indicating that a predetermined signal is transmitted by the RRC (radio resource control) message to the terminal device. At this time, the radio resource for transmitting the predetermined signal (frequency and time resources such as transmission timing in each frequency band) may be notified. Further, the base station apparatus may notify the presence / absence of transmission of a predetermined signal and the radio resource at the time of transmission by a signal other than the RRC message. Further, the base station apparatus may broadcast the presence / absence of transmission of a predetermined signal such as SRS by, for example, system information (SI). The terminal device may select the precoding matrix (PMI) used by the base station device based on the CSI-RS when there is no transmission of a predetermined signal such as SRS. Note that CSI-RS is an example, in which case the terminal device estimates the transmission line and precodes a transmission line based on another signal transmitted by the base station device, which has a narrower frequency range than a predetermined signal. May be selected.

As described above, according to the present embodiment, by enabling the base station device to transmit a predetermined signal that enables transmission path estimation in a terminal device such as SRS, the base station in each frequency domain of the terminal device can be transmitted. It allows the device to select the beam to be used. This makes it possible for the base station device to form a beam suitable for the frequency resource used in downlink communication.

(Device configuration)
Subsequently, a hardware configuration example of the base station device and the terminal device as described above will be described with reference to FIG. The base station device and the terminal device are configured to include, in one example, a processor 201, a ROM 202, a RAM 203, a storage device 204, and a communication circuit 205. The processor 201 is a computer including one or more processing circuits such as a general-purpose CPU (central processing unit) and an ASIC (integrated circuit for a specific application), and is stored in a ROM 202 or a storage device 204. By reading and executing the existing program, the entire processing of the base station device and the terminal device and each of the above-mentioned processes are executed. The ROM 202 is a read-only memory that stores information such as programs and various parameters related to processing executed by the base station device and the terminal device. The RAM 203 is a random access memory that functions as a workspace when the processor 201 executes a program and stores temporary information. The storage device 204 is configured by, for example, a detachable external storage device or the like. The communication circuit 205 is composed of, for example, a circuit for LTE or 5G wireless communication. Although one communication circuit 205 is shown in FIG. 2, a plurality of base station devices and terminal devices include, for example, a wireless communication circuit for LTE and 5G, and a wired communication circuit for wired communication. It may have a communication circuit. The base station device and the terminal device may have separate communication circuits 205 for each of the plurality of usable frequency bands, or a common communication circuit 205 for at least a part of those frequency bands. You may have.

FIG. 3 shows an example of the functional configuration of the base station apparatus according to the present embodiment. The base station apparatus has, for example, a communication unit 301, a transmission path estimation signal transmission unit 302, a beam setting unit 303, and an information notification unit 304 as an example of its functional configuration. Note that FIG. 3 shows only the portion of the functions of the base station device that are related to the description of the present embodiment, and the base station device functions as a base station device of a general cellular communication system. Naturally have. Further, the base station device may have a function other than the function shown in FIG. 3 and the general-purpose function as the base station device. Further, the functional blocks in FIG. 3 are schematically shown, and each functional block may be integrated or further subdivided. Each function of FIG. 3 may be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204, for example, the processor existing inside the communication circuit 205 may execute predetermined software. It may be realized by executing.

The communication unit 301 performs wireless communication with the terminal device. The communication unit 301 forms a beam using a plurality of antennas and transmits a signal. The transmission line estimation signal transmission unit 302 executes a process for transmitting a predetermined signal (for example, SRS) for estimation of the transmission line by the terminal device via the communication unit 301. Here, the predetermined signal is transmitted over the entire available frequency band, unlike, for example, the Channel State Information-Reference Signal (CSI-RS), which is transmitted only in a partial frequency range. The terminal device receives the predetermined signal and estimates the transmission path based on the received predetermined signal. Then, the terminal device identifies a precoding matrix suitable for use by the base station device for each of the plurality of frequency domains from the candidates of the plurality of precoding matrices based on the estimated value of the transmission line. .. The plurality of frequency domains are each a part of the frequency band that can be used in the wireless communication system. The identified precoding matrix is notified to the base station apparatus by a signal containing information about the identification result.

The beam setting unit 303 acquires information on the precoding matrix for each of the plurality of frequency domains from the terminal device via the communication unit 301. Then, the beam setting unit 303 sets the antenna weight used by the communication unit 301 by using the precoding matrix for the frequency domain corresponding to the frequency resource used by the communication unit 301 to transmit the signal to the terminal device. .. As a result, the communication unit 301 can transmit a signal to the terminal device with a beam suitable for the frequency resource to be allocated. The information notification unit 304 notifies the terminal device of various information via the communication unit 301. For example, when the transmission path estimation signal transmission unit 302 transmits a predetermined signal such as SRS, the information notification unit 304 transmits information indicating that the predetermined signal is transmitted via the communication unit 301. Can be notified to. The information indicating that the predetermined signal is transmitted can be expressed as 1-bit information. In one example, it may be shown that a predetermined signal is transmitted by setting a bit as a reserved bit to 1 in an existing signal such as system information or a message of a higher layer. Further, a bit indicating whether or not to transmit a predetermined signal may be added to the existing message, or a new message may be specified separately.

FIG. 4 shows an example of the functional configuration of the terminal device according to the present embodiment. The terminal device has, for example, a communication unit 401, a transmission path estimation unit 402, a beam determination unit 403, and an information reception unit 404 as examples of its functional configuration. Note that FIG. 4 shows only the portion of the functions of the terminal device that are related to the description of the present embodiment, and the terminal device naturally has a function as a terminal device of a general cellular communication system. .. Further, the terminal device may have a function other than the function shown in FIG. 4 and the general-purpose function as the terminal device. Further, the functional blocks in FIG. 4 are schematically shown, and each functional block may be integrated or further subdivided. Each function of FIG. 4 may be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204, for example, the processor existing inside the communication circuit 205 may execute predetermined software. It may be realized by executing.

The communication unit 401 performs wireless communication with the base station device. When the terminal device has a plurality of antennas, the communication unit 401 may form a beam using the plurality of antennas and transmit / receive a signal to / from the base station device. The transmission line estimation unit 402 receives a predetermined signal such as SRS transmitted from the base station device over the entire frequency band, and receives each of one or more antennas of the base station device and a plurality of antennas of the terminal device. Estimate the state of the transmission line between each of the antennas. The transmission line estimation unit 402 acquires, for example, an estimated value of the state of the transmission line for each of a plurality of frequency domains. The plurality of frequency domains are each a part of the frequency band that can be used in the wireless communication system.

The beam determination unit 403 determines for each of the plurality of frequency domains by selecting the precoding matrix to be used by the base station apparatus from the precoding matrix candidates prepared in advance. Then, the beam determination unit 403 notifies the base station apparatus of the information of the selected precoding matrix for each of the plurality of frequency domains. For example, each PMI in a plurality of frequency domains may be notified to the base station apparatus. Further, for example, a PMI suitable for the entire usable frequency band is used as a reference PMI, and the value of the PMI and the difference value between the PMIs of the plurality of frequency regions are notified to the base station apparatus. May be good. At this time, a bitmap indicating whether or not the reference PMI value and the PMI value for each of the plurality of frequency regions is equal to the reference PMI value may be notified to the base station apparatus. Further, as the reference PMI value, the PMI value having the highest appearance frequency among the PMIs for each of the plurality of frequency regions may be used.

The information receiving unit 404 receives, for example, information indicating whether or not a predetermined signal such as SRS is transmitted by the base station apparatus. When the information receiving unit 404 receives information indicating that a predetermined signal is transmitted, the transmission line estimation unit 402 executes transmission line estimation based on the predetermined signal. Then, as described above, the beam determination unit 403 determines the precoding matrix for each of the plurality of frequency domains, and notifies the base station apparatus of the result. On the other hand, when the information receiving unit 404 receives information indicating that a predetermined signal is not transmitted, the transmission line estimation unit 402 can execute the transmission line estimation based on, for example, CSI-RS. Then, the beam determination unit 403 selects a precoding matrix based on the transmission path estimated value, and notifies the base station apparatus of the corresponding PMI. The information notified to the base station apparatus is, for example, whether to notify the PMI for a plurality of frequency domains determined based on a predetermined signal, or to notify one PMI determined based on CSI-RS. May include information indicating.

(Process flow)
Subsequently, an example of the flow of processing executed by the base station device and the terminal device will be described with reference to FIGS. 5 and 6. FIG. 5 shows an example of a process flow executed by the base station device, and FIG. 6 shows an example of a process flow executed by the terminal device. This process is started, for example, by the processor 201 of the base station device or the terminal device activating the program stored in the ROM 202.

First, the base station apparatus notifies the terminal apparatus of information indicating that a predetermined signal for estimating a transmission path such as SRS is transmitted (S501), and the terminal apparatus receives the notification (S601). It should be noted that this notification may be notified individually to the terminal devices, or may be notified to a plurality of terminal devices at the same time by broadcasting or multicast. In one example, the notification here notifies the frequency / time resource to which a predetermined signal for channel estimation is transmitted. Although the predetermined signal is transmitted over the entire usable frequency band, it may be transmitted at different timings for each frequency domain, or may be transmitted all at once in all frequency bands. Here, when predetermined signals are transmitted all at once in all frequency bands, only the transmission timing can be notified. Further, when a predetermined signal is transmitted at different timings for each frequency domain, the transmission timing may be individually indicated for each of a plurality of divided frequency domains. Further, for example, the reference transmission timing for the reference frequency region may be indicated, and for other frequency regions, the transmission timing may be indicated by the difference (offset value) from the reference transmission timing. Note that this notification does not necessarily have to be sent and received.

Then, the base station apparatus transmits a predetermined signal for transmission path estimation (S502), and the terminal apparatus receives the signal for transmission path estimation, and based on the signal, for each of the plurality of frequency domains. Perform transmission path estimation (S602). Here, the plurality of frequency domains are each a part of the frequency band that can be used in the wireless communication system. The base station apparatus may indicate that the predetermined signal is transmitted by indicating that this signal includes the predetermined signal inside the predetermined signal. In this case, the notification of S501 and S502 Can be transmitted simultaneously (in the same subframe) with a given signal. Further, when the base station apparatus is to always transmit a predetermined signal, transmission / reception of notifications of S501 and S601 may be omitted.

The terminal device selects a precoding matrix for each of the plurality of frequency domains from the candidates of the precoding matrix prepared in advance based on the transmission line estimates for the plurality of frequency domains. Determine (S603). Then, the terminal device notifies the base station device of the information regarding the determined precoding matrix (S604). The terminal device may transmit, for example, information indicating the PMI for each frequency domain to the base station device. At this time, as described above, the reference PMI and the difference value between the reference PMI and the reference PMI in each frequency domain may be transmitted, or the PMI in each frequency domain may be transmitted without using the reference PMI. The value itself may be sent. Further, only information on whether or not the PMI in each frequency region is equal to the reference PMI may be notified.

The base station device receives information about the precoding matrix from the terminal device (S503). Then, the base station apparatus determines the frequency resource to be used for signal transmission to the terminal apparatus (S504), identifies the PMI for the frequency domain corresponding to the frequency resource, and beams with the precoding matrix corresponding to the PMI. Is formed and a signal is transmitted to the terminal device (S505). The base station apparatus may select, for example, a frequency resource that can use the same antenna weight. That is, the frequency domain in which the PMIs are common may be specified, and the frequency resource to be used may be determined within the frequency domain.

In this way, the base station device transmits a predetermined signal for transmission path estimation by a terminal device such as SRS over the entire available frequency band. This allows the terminal device to perform transmission path estimation over the entire available frequency band, and to select an appropriate precoding matrix for each frequency domain corresponding to a part of a wide range of frequency bands. can. As a result, the base station device can form a beam suitable for the frequency resource used for signal transmission to the terminal device and transmit the signal to the terminal device with high efficiency.

The invention is not limited to the above embodiment, and various modifications and changes can be made within the scope of the gist of the invention.

Claims (14)

It ’s a base station device,
It has multiple antennas and communication means,
The communication means is
A predetermined signal for estimation of a transmission line by a terminal device is transmitted from each of the plurality of antennas over the entire available frequency band.
For each of the plurality of frequency domains, information about the precoding matrix to be used by the base station apparatus is received from the terminal apparatus, and each of the plurality of frequency domains is a part of the available frequency band.
A beam is formed based on the frequency resource to be used for signal transmission to the terminal device and the received information, and the signal is transmitted to the terminal device.
A base station appliance characterized by being configured in such a manner. The base station device according to claim 1, wherein the communication means notifies the terminal device of information indicating that the predetermined signal is transmitted when the predetermined signal is transmitted. The communication means identifies a frequency domain corresponding to a frequency resource to be used for signal transmission to the terminal device from the plurality of frequency domains, and precodes the specified frequency domain corresponding to the received information. The base station apparatus according to claim 1 or 2, wherein a beam is formed using a matrix and a signal is transmitted to the terminal apparatus. The communication means according to claim 1 or 2, wherein the communication means determines a frequency resource to be used for signal transmission to the terminal device from the frequency domain in which the precoding matrix is common in the received information. The base station equipment described. The base station apparatus according to any one of claims 1 to 4, wherein the predetermined signal is an SRS (Sounding Reference Signal). It ’s a terminal device,
A receiving means for receiving a predetermined signal for estimating a transmission line by the terminal device, transmitted from each of a plurality of antennas of the base station device over the entire available frequency band.
An estimation means for estimating the state of a transmission line for each of a plurality of frequency domains based on the predetermined signal, and an estimation means.
A determination means for determining the precoding matrix to be used by the base station apparatus in each of the plurality of frequency domains based on the estimated state of the transmission line.
A transmission means for transmitting information about a precoding matrix to be used in each of the determined plurality of frequency domains to the base station apparatus, and a transmission means.
Have,
Each of the plurality of frequency domains is part of the available frequency band.
A terminal device characterized by that. The receiving means receives information indicating whether or not the predetermined signal is transmitted from the base station apparatus, and receives information indicating whether or not the predetermined signal is transmitted from the base station apparatus.
The estimation means estimates the state of a transmission line for each of the plurality of frequency domains when information indicating that the predetermined signal is transmitted from the base station apparatus is received.
The terminal device according to claim 6. The estimation means is based on a second predetermined signal transmitted in a frequency range narrower than the predetermined signal when information indicating that the predetermined signal is not transmitted from the base station apparatus is received. The terminal device according to claim 7, wherein the transmission path is estimated. 6. The terminal device according to item 1. The terminal device according to any one of claims 6 to 9, wherein the predetermined signal is an SRS (Sounding Reference Signal). A communication method performed by a base station device having multiple antennas.
To transmit a predetermined signal for estimation of a transmission line by a terminal device from each of the plurality of antennas over the entire available frequency band.
Receiving information from the terminal device about the precoding matrix to be used by the base station device for each of the plurality of frequency domains.
Forming a beam based on the frequency resource to be used for signal transmission to the terminal device and the received information, and transmitting the signal to the terminal device.
Including
Each of the plurality of frequency domains is part of the available frequency band.
A communication method characterized by that. A communication method executed by a terminal device.
Receiving a predetermined signal for estimating a transmission line by the terminal device transmitted from each of the plurality of antennas of the base station device over the entire available frequency band.
Estimating the state of the transmission line for each of the plurality of frequency domains based on the predetermined signal,
Determining the precoding matrix to be used by the base station apparatus in each of the plurality of frequency domains based on the estimated state of the transmission line.
Sending information about the precoding matrix to be used in each of the determined frequency domains to the base station apparatus, and
Including
Each of the plurality of frequency domains is part of the available frequency band.
A communication method characterized by that. A program for making a computer function as each means included in the base station apparatus according to any one of claims 1 to 5. A program for making a computer function as each means included in the terminal device according to any one of claims 6 to 10.

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