JP7570988B2 - Control device, control method, and program for reducing delay in wireless communication - Google Patents

Description

The present invention relates to a technology for reducing delays in wireless communication in a cellular communication system.

There is a demand for low-latency communications in cellular communication systems, and the Third Generation Partnership Project (3GPP) is studying technologies to achieve ultra-reliable and low-latency communications (URLLC).

The present invention provides a technology that reduces delays in wireless communication in a cellular communication system.

A control device according to one aspect of the present invention has, when a plurality of terminal devices are connected to a base station device that communicates using time division duplexing (TDD) that is pre-configured so that a first time slot, which is a part of a pre-defined plurality of time slots, includes a first frequency resource for downlink and a second frequency resource for uplink, the second frequency resource being different from the first frequency resource, at a common timing, the base station device, and an identification means for identifying, from among the plurality of terminal devices, a first terminal device that performs downlink communication in the first time slot and a second terminal device that performs uplink communication, based on at least one of first information corresponding to a state of a transmission path between each of the plurality of terminal devices and the base station device and second information corresponding to a distance between each of the plurality of terminal devices and the base station device; and a control means for controlling the base station device to perform downlink communication with the first terminal device and uplink communication with the second terminal device in the first time slot.

The present invention can reduce delays in wireless communication in a cellular communication system.

FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. FIG. 2 illustrates an example of resource allocation for uplink/downlink communications. FIG. 13 is a diagram illustrating selection of a terminal device to perform communication. FIG. 13 is a diagram illustrating selection of a terminal device to perform communication. FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station device. FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. FIG. 11 is a diagram illustrating an example of a flow of processing performed by a base station device.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims, 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 combination. In addition, the same reference numbers are used for the same or similar configurations, and duplicate descriptions are omitted.

(Configuration of communication system)
FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. The wireless communication system is, for example, a wireless communication system conforming to the fifth generation (5G) cellular wireless communication standard defined by the Third Generation Partnership Project (3GPP). Note that this is only an example, and other wireless communication systems may be used. The wireless communication system includes, for example, a base station device 101, a terminal device 102, and a terminal device 103. Communication between the base station device 101 and the terminal device 102 and the terminal device 103 may be performed using a method of generating a time domain signal by mapping a signal to be transmitted on a frequency axis and performing a Fourier transform, such as OFDMA (orthogonal frequency division multiple access). Note that, for the sake of simplicity, FIG. 1 shows only a small number of base station devices and terminal devices, but naturally, there may be a larger number of base station devices and terminal devices than these.

In this wireless communication system, time division duplex (TDD) is used for communication between the base station device and the terminal device. In TDD, a common frequency resource is divided into time slots, and each of the time slots is assigned to either the uplink (the link from the terminal device to the base station device) or the downlink (the link from the base station device to the terminal device). Here, when the terminal device transmits data on the uplink, the following procedure occurs: the terminal device transmits a scheduling request (SR) to the base station device, the base station device assigns radio resources to the terminal device to have it report a buffer status report (BSR), the terminal device transmits the BSR using the radio resources, the base station device assigns radio resources for data transmission based on the BSR, and the terminal device transmits data using the radio resources. At this time, in a system using TDD, after an SR is transmitted to a base station device using uplink resources, radio resource allocation for a BSR is notified to a terminal device using downlink resources, the BSR is then transmitted to the base station device using uplink resources, radio resource allocation for data transmission is performed using the subsequent downlink resources, and the data is then transmitted using the subsequent uplink resources. This can result in a long period of time between when the terminal device transmits an SR and when the data is actually transmitted.

For this reason, in this embodiment, as shown in FIG. 2, in a certain frequency resource, a time slot that is assigned to the downlink (DL) in another frequency resource is assigned to the uplink (UL). Note that FIG. 2 shows an example in which a frequency resource used only for uplink communication is provided in the center of the frequency range of a component carrier (CC). In this way, the above-mentioned period can be shortened by assigning the time slot assigned to the downlink in the first frequency resource to the uplink in the second frequency resource. Note that the assignment of time slots to uplink communication and downlink communication as shown in FIG. 2 is one example, and other time slot assignments may be used. For example, the assignment of downlink and uplink in the first frequency resource in a part other than the center of the CC may be an assignment such that more downlink or uplink time slots are prepared. Also, in the second frequency resource in the center of the CC, no time slots are assigned to downlink communication, but some time slots may be assigned for downlink communication. That is, any allocation may be used within the CC as long as a first frequency resource using a first allocation of time slots to the downlink and uplink and a second frequency resource using a second allocation are configured to exist. In the above description, it has been described that there are frequency resources with different time slot allocations within the CC, but this is not limited to this. The above CC may be interpreted as a predetermined frequency band in which reception processing including fast Fourier transform (FFT) is performed collectively in the terminal device.

That is, for example, when data to be transmitted occurs in a time slot allocated to the downlink in the first frequency resource, the terminal device can transmit an SR in the second frequency resource without waiting for the arrival of a time slot allocated to the uplink in the first frequency resource. Also, when the base station device receives an SR during a period in which the first frequency resource is allocated to the downlink, the base station device can transmit a signal allocating radio resources for the BSR during that period in the first frequency resource. Here, by using the second frequency resource, radio resources in the period in which the first frequency resource is allocated to the downlink can be allocated for the BSR. Therefore, the terminal device can report a BSR in the second frequency resource without waiting for the time slot in which the first frequency resource is allocated to the uplink. After that, when the base station device receives a BSR during a period in which the first frequency resource is allocated to the downlink, the base station device can transmit a signal allocating radio resources for data during that period in the first frequency resource. The terminal device can transmit data in the second frequency resource without waiting for the time slot in which the first frequency resource is allocated to the uplink.

In this manner, in this embodiment, a first frequency resource according to a first allocation of time slots to uplink communication and downlink communication, and a second frequency resource according to a second allocation different from the first allocation, are prepared. Then, it is possible to use a time slot assigned to the downlink in the first frequency resource and to the uplink in the second frequency resource. This makes it possible to transmit, for example, an SR or a BSR in the second frequency resource, as described above, without waiting for a time slot assigned to the uplink in the first frequency resource, thereby shortening the period until uplink data is transmitted.

On the other hand, when the configuration as shown in FIG. 2 is used, the uplink communication and the downlink communication are performed in the same time slot. For example, as shown in FIG. 1, when a signal is transmitted from the base station device 101 to the terminal device 102 using the first frequency resource, a signal can be transmitted from the terminal device 103 to the base station device 101 using the second frequency resource. In this case, the terminal device 102 receives the signal from the base station device 101 and the signal from the terminal device 103 in parallel, and performs reception processing including Fourier transform on these signals collectively. At this time, for example, when the terminal device 103 exists in the vicinity of the terminal device 102, the reception power of the signal transmitted by the terminal device 103 at the terminal device 102 may be significantly larger than the reception power of the signal transmitted from the base station device 101 at the terminal device 102. In this case, the signal from the terminal device 103 may have a dominant power with respect to the entire received signal. As a result, the signal from the base station device 101 is buried in the noise level, and the terminal device 102 may fail to process the signal. Furthermore, the terminal device 103 adjusts the transmission timing so that the timing of the OFDM symbols received from multiple terminal devices at the base station device 101 is approximately the same, but the transmission timing does not take into account the reception timing at the terminal device 102. For this reason, if the terminal device 102 performs a Fourier transform at a timing based on the signal received from the base station device 101, the orthogonality of the signal received from the terminal device 103 will be lost, and interference may occur with the signal from the base station device 101.

In this embodiment, taking such interference into consideration, a combination of a first terminal device performing downlink communication and a second terminal device performing uplink communication is determined. That is, even if downlink communication by the first terminal device and uplink communication by the second terminal device are performed in the same time slot, a combination of the first terminal device and the second terminal device is selected so that interference between these signals is suppressed (at least so that the effect of interference caused by uplink communication of the second terminal device on downlink communication of the first terminal device is sufficiently suppressed).

In this embodiment, the base station device identifies two terminal devices (a pair of terminal devices) that are separated in at least one of the direction and distance from the base station device, and one of the two terminal devices is the above-mentioned first terminal device, and the other is the second terminal device. For example, the base station device can use the direction of the beam when communicating with each terminal device as the direction of each terminal device as seen from the base station device. That is, the base station device selects two terminal devices with sufficiently different beam directions, and performs uplink communication with one of the two terminal devices and downlink communication with the other in the same time slot. The beam direction corresponds to the state of the transmission path between the base station device and each terminal device. For this reason, the base station device can, for example, acquire a value indicating the state of the transmission path for each terminal device, and identify a pair of terminal devices such that the correlation value of the value indicating the state of the transmission path does not exceed a predetermined value. That is, it is assumed that the difference in the beam direction is small for two terminal devices with a high correlation value of the value indicating the state of the transmission path, and that they are located relatively close to each other, so that interference will occur if they communicate in the same time slot. For this reason, two terminal devices whose correlation value is lower than a predetermined value and whose corresponding beam directions are expected to be sufficiently different are selected as a pair. Note that the value indicating the state of the transmission path may be, for example, channel state information (CSI) or a transmission path estimation value acquired by the base station device based on a sounding reference signal (SRS).

The base station device may specify the direction of the terminal device as seen from the base station device by a precoding matrix indicator (PMI) instead of a value indicating the state of the transmission path. The PMI is information indicating the beam to be used by the base station device, which is specified based on the state of the transmission path in the terminal device. In other words, the PMI is also information corresponding to the state of the transmission path between the base station device and the terminal device. The base station device may specify two terminal devices with different PMIs as a pair of terminal devices that communicate in the same time slot. The base station device may select the first terminal device and the second terminal device so that the difference in direction between the first beam corresponding to the PMI of the first terminal device and the second beam corresponding to the PMI of the second terminal device exceeds a predetermined level, that is, so that the directions are sufficiently apart. For example, a terminal device that reports a PMI corresponding to a beam that is close to a certain degree, such as a PMI corresponding to an adjacent beam, to the base station device may not be selected as a pair.

As described above, the base station device can identify a pair of a first terminal device performing downlink communication and a second terminal device performing uplink communication based on first information corresponding to the state of the transmission path between multiple terminal devices, and communicate with the first terminal device and the second terminal device in the same time slot. The first terminal device is selected from among the terminal devices that should perform downlink communication, and the second terminal device is selected from among the terminal devices that should perform uplink communication. In this way, by selecting two terminal devices that are sufficiently different in direction as seen from the base station device, it is possible to sufficiently suppress the interference that occurs between these terminal devices when they communicate in the same time slot.

In place of or in addition to the first information corresponding to the state of the transmission path between each of the multiple terminal devices, the base station device may identify a pair of a first terminal device performing downlink communication and a second terminal device performing uplink communication based on second information corresponding to the distance between each of the multiple terminal devices. This is because even if a terminal device located near the base station device and a terminal device located at a long distance, such as the edge of the area formed by the base station device, perform communication in parallel, the effect of interference between the terminal devices can be sufficiently suppressed to a small value.

For example, the base station device may acquire values indicating the distance between each of the multiple terminal devices and the base station device itself, and select two terminal devices whose difference between the values is equal to or greater than a predetermined threshold as terminal devices that communicate in the same time slot. In one example, the distance between the terminal device and the base station device may be specified based on the location information of the terminal device. It is also assumed that the further away each terminal device is from the base station device, the lower the reception power of the signal from the base station device in that terminal device. For this reason, the base station device may acquire information on the reception power of a predetermined signal transmitted from the base station device in each of the multiple terminal devices (for example, by a report from the terminal device), and specify a pair of terminal devices whose difference in reception power is equal to or greater than a predetermined threshold as terminal devices that communicate in the same time slot. The predetermined signal may be, for example, a reference signal, and the information on the reception power of the reference signal may be reference signal reception power (RSRP). In addition, the further away each terminal device is from the base station device, the earlier the timing at which the terminal device transmits a signal in order to synchronize the reception timing at the base station device. For this reason, the base station device may use information indicating this timing, i.e., the value of the timing advance (TA), to identify a pair of terminal devices whose TA value difference is equal to or exceeds a predetermined threshold value as terminal devices that communicate in the same time slot.

The process in which the base station device identifies a pair of terminal devices that communicate in the same time slot based on at least one of the first information and the second information described above will be described with reference to Figures 3 and 4. In the following example, the PMI is used as the first information corresponding to the state of the transmission path between the base station device and the terminal device, and the TA is used as the second information corresponding to the distance between the base station device and the terminal device.

Figure 3 shows an example of a system in which a base station device 301 forms multiple beams 311-317 to communicate. Each of the multiple beams 311-317 is associated with a different PMI value, and the base station device 301 can use a beam corresponding to the PMI value determined and fed back based on the result of the transmission path estimation in the terminal device for communication with the terminal device. For example, since terminal device 321 receives the signal of beam 311 most strongly, it feeds back the PMI of beam 311 to the base station device 301. From this feedback, the base station device 301 can estimate that terminal device 321 exists in the direction of beam 311. Similarly, the base station device 301 can estimate that terminal device 322 and terminal device 323 exist in the direction of beam 312, terminal device 324 exists in the direction of beam 314, terminal device 325 exists in the direction of beam 316, and terminal device 326 and terminal device 327 exist in the direction of beam 317. Therefore, the base station device 301 may identify a pair of terminal devices that communicate in the same time slot for uplink communication and downlink communication, so that, for example, the terminal device 322 and the terminal device 323 are not paired, and the terminal device 326 and the terminal device 327 are not paired. In addition, for example, the terminal devices that have fed back PMIs corresponding to adjacent beams may not be paired. For example, the base station device 301 may identify a pair of terminal devices that communicate in the same time slot for uplink communication and downlink communication, so that the terminal device 325 and the terminal device 326 or the terminal device 327 are not paired. In this way, the base station device 301 can prevent an uplink signal from a certain terminal device from interfering with a downlink communication to another terminal device by preventing terminal devices that are close to each other from communicating in the same time slot based on information (e.g., PMI) corresponding to the state of the transmission path between the terminal devices.

The base station device 301 can also estimate the distance of each terminal device from the base station device 301 according to the value of the TA to be applied to each terminal device. For example, terminal device 321 and terminal device 327 are located near the base station device 301 and have a small propagation delay, so a small value is set as the TA. On the other hand, terminal devices 322 to 324 and terminal device 326 are located far from the base station device 301 and have a large propagation delay, so a large value is set as the TA. In this way, the value of the TA is determined according to the propagation delay and corresponds to the distance between the base station device 301 and each terminal device. Then, the base station device 301 can identify pairs of terminal devices that communicate in the same time slot for uplink communication and downlink communication so that terminal devices with a small difference in TA are not paired. For example, the base station device 301 can prevent terminal device 321 from pairing with terminal device 327. Although terminal device 321 and terminal device 327 are located in different directions, they are located close to each other, so interference may occur if uplink communication and downlink communication are performed in the same time slot. In addition, base station device 301 may prevent terminal device 322 and terminal device 323 from being paired. In this way, base station device 301 can prevent two terminal devices with a small difference in distance from its own device from communicating in the same time slot based on the distance between each terminal device, thereby preventing uplink signals from one terminal device from interfering with downlink communication to another terminal device.

The base station device 301 may also use both information corresponding to the state of the transmission path between each terminal device (here, PMI) and information corresponding to the distance between each terminal device (here, TA) to identify a pair of terminal devices that communicate in the same time slot for uplink communication and downlink communication. For example, the base station device 301 may select two terminal devices as a pair so that both the PMI and TA are sufficiently different. For example, as shown in FIG. 4, the base station device 301 may classify terminal devices according to three categories for the TA value: greater than a first predetermined value (TA large), less than or equal to the first predetermined value and greater than a second predetermined value (TA medium), and less than or equal to the second predetermined value (TA small), as well as a category according to the PMI value, and may select two terminal devices with different TA categories and PMI categories as a pair of terminal devices. This makes it possible to prevent an uplink signal from a certain terminal device from interfering with downlink communication to another terminal device.

Here, it has been described that a pair of two terminal devices that communicate in the same time slot is specified, but these two terminal devices are, for example, terminal devices in which one can perform uplink communication and the other can perform downlink communication in adjacent frequency resources, and in other frequency resources, terminal devices other than these two terminal devices can also communicate in the same time slot. For example, when there is a specific terminal device that needs to communicate in the uplink, based on the above-mentioned first information and second information, other terminal devices that are at least one of the following, that is, the direction seen from the base station device is sufficiently different from that of the specific terminal device, or the distance from the base station device is sufficiently different from that of the specific terminal device, can perform downlink communication in adjacent frequency resources, and other terminal devices that are close in direction or distance can perform downlink communication in resources that are far away in the frequency domain. In other words, the allocation of frequency resources may be determined based on at least one of the above-mentioned first information and second information.

The base station device may initially identify a pair of terminal devices and communicate without using either the first information or the second information as described above, and may identify a pair of terminal devices based on at least one of the first information and the second information when the communication quality of the downlink communication deteriorates during the communication. That is, the above-mentioned processing may be performed after a state in which interference with the downlink signal by the uplink signal is assumed to have occurred as a result of a mixture of uplink communication and downlink communication. In addition, when the base station device selects a pair of terminal devices based on at least one of the first information and the second information and communicates, if the communication quality of the downlink communication deteriorates during the communication, the base station device may identify the pair of terminal devices again. This makes it possible to suppress the occurrence of interference by following changes in the situation due to the movement of the terminal devices, etc.

The base station device may determine the success rate of downlink communication based on, for example, the ratio of negative acknowledgements (NACKs) received from the terminal device that is the destination of the downlink user data to the number of transmissions of the downlink user data, and may determine that the communication quality of the downlink communication has deteriorated when the success rate falls below a predetermined value. The base station device may also determine that the communication quality of the downlink communication has deteriorated when the success rate of the downlink communication continues to fall below a predetermined value for a predetermined period of time. The base station device may also determine that the communication quality of the downlink communication has deteriorated when the communication speed of the downlink communication has decreased. For example, the base station device adjusts the modulation and coding scheme (MCS) in response to receiving a negative acknowledgement, etc., but as a result, the modulation scheme or coding scheme may be changed to a more robust scheme due to an error, resulting in a decrease in the communication speed. In other words, the base station device may determine that the communication quality of the downlink communication has deteriorated when the MCS is changed to slow down the communication speed. In addition, the base station device may determine that the communication quality of the downlink communication has deteriorated if an MCS corresponding to a communication speed lower than a predetermined communication speed is selected, or if an MCS corresponding to a communication speed lower than a predetermined communication speed continues to be selected for a certain period of time.

In this way, by re-identifying the combination of a terminal device performing uplink communication and a terminal device performing downlink communication based on the deterioration of communication quality in downlink communication, it is possible to follow the situation change due to the movement of the terminal device, etc., and suppress the occurrence of interference. Note that the downlink communication whose communication quality is monitored here is, for example, downlink communication performed in another frequency resource that exists within a predetermined frequency range from the predetermined frequency resource in which the uplink communication is performed. In other words, downlink communication in a frequency resource that is far away in the frequency direction to the extent that the influence of the uplink communication is sufficiently reduced does not need to be taken into consideration.

In the above description, the base station device identifies a pair of terminal devices and communicates with the terminal devices. However, for example, a control device different from the base station device may identify a pair of terminal devices. For example, the control device acquires, for each of a plurality of terminal devices connected to each of a plurality of base station devices, first information corresponding to the state of the transmission path between the base station device to which the terminal device is connected and the terminal device, and second information corresponding to the distance between the base station device to which the terminal device is connected and the terminal device. Then, the control device roughly estimates the distance between the terminal devices based on the first information and the second information, and identifies a pair of terminal devices so that the distance is sufficiently large. Then, the control device may instruct the base station device to which the terminal devices are connected so that one of the identified pair of terminal devices performs uplink communication and the other performs downlink communication in the same time slot. In this way, the control device can select a pair of terminal devices so as to suppress the effect of interference even between a plurality of terminal devices each connected to another adjacent base station device. The control device may be included inside the base station device, or may be prepared independently of the base station device. In this way, the above-mentioned "base station device" may be interpreted as a "control device" that controls each of the one or more base station devices based on information collected from the one or more base station devices, for example.

(Device configuration)
An example of the hardware configuration of the base station device will be described with reference to FIG. 5. In one example, the base station device includes a processor 501, a ROM 502, a RAM 503, a storage device 504, and a communication circuit 505. The processor 501 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 executes the overall processing of the device and each of the above-mentioned processes by reading and executing a program stored in the ROM 502 or the storage device 504. The ROM 502 is a read-only memory that stores information such as a program related to the processing executed by the base station device and various parameters. The RAM 503 functions as a workspace when the processor 501 executes a program, and is a random access memory that stores temporary information. The storage device 504 is, for example, a removable external storage device. The communication circuit 505 is, for example, a circuit for wireless communication of LTE or 5G. Although one communication circuit 505 is illustrated in FIG. 5, the base station device may have multiple communication circuits. For example, the base station device may have a common antenna with wireless communication circuits for LTE and 5G. The base station device may have an antenna for LTE and an antenna for 5G separately. The base station device may also have a communication circuit for wired communication, for example, for communication with other base station devices or network nodes. The base station device may have separate communication circuits 505 for each of a plurality of usable frequency bands, or may have a common communication circuit 505 for at least some of the frequency bands.

Figure 6 is a diagram showing an example of the functional configuration of a base station device. The base station device is configured to include, as its functions, a direction information acquisition unit 601, a distance information acquisition unit 602, a communication target terminal identification unit 603, and a communication processing unit 604. Note that these functional units can be realized, for example, by the processor 501 executing a program stored in the ROM 502 or the storage device 504. Note that the processes executed by each functional unit can be modified as described above, but the details will not be repeated here.

The direction information acquisition unit 601 acquires first information indicating the direction of the position of each terminal device as seen from the base station device, such as information corresponding to the state of the transmission path between each of the multiple terminal devices and the base station device. For example, the direction information acquisition unit 601 acquires information such as PMI information of each terminal device and a transmission path estimation value based on the SRS transmitted from each terminal device. Note that the direction information acquisition unit 601 may acquire, for example, location information of the terminal device and specify the direction in which the terminal device is located based on the location information. The distance information acquisition unit 602 acquires second information corresponding to the distance between each of the multiple terminal devices and the base station device. For example, the distance information acquisition unit 602 may acquire the distance from the location information of the terminal device, or may acquire a value that varies depending on the distance, such as the TA or the received power of a predetermined signal such as a reference signal. The communication target terminal identification unit 603 identifies a first terminal device performing downlink communication and a second terminal device performing uplink communication, which are in a relationship in which interference between the signals of the two devices can be sufficiently suppressed, based on at least one of the information acquired by the direction information acquisition unit 601 and the information acquired by the distance information acquisition unit 602. The communication processing unit 604 performs downlink communication with the first terminal device and uplink communication with the second terminal device in the same time slot.

(Processing flow)
Next, an example of the flow of the process executed by the base station device will be outlined with reference to Fig. 7. Note that the flow of the process described below is only an example, and the above-mentioned modifications are naturally possible. Also, each step of the following process may be interchanged with another, or some of the processes may be omitted.

In this process, the base station device first acquires information corresponding to the direction of each of the multiple terminal devices as seen from the base station device, that is, first information corresponding to the state of the transmission path between each of the multiple terminal devices (S701). The first information may be, for example, a transmission path estimation value based on PMI or SRS transmitted from the terminal device. The base station device also acquires second information corresponding to the distance between the multiple terminal devices (S702). The second information may be, for example, TA or RSRP. The base station device identifies the first terminal device that performs downlink communication and the second terminal device that performs uplink communication based on the first information or the second information, or based on both the first information and the second information (S703). Then, the base station device performs downlink communication with the first terminal device and uplink communication with the second terminal device in the same time slot (S704).

In this way, in a time slot in which uplink and downlink communications are mixed, it is possible to determine the terminal device that performs downlink communications and the terminal device that performs uplink communications so that the uplink communications do not interfere with the downlink communications. This makes it possible to promote the mixed use of multiple allocation patterns of time slots for uplink and downlink communications, thereby making it possible to reduce delays in wireless communications.

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

Claims (15)

A control device,
a determination means for determining, when a plurality of terminal devices are connected to a base station device that communicates using time division duplexing (TDD) that is pre-configured so that a first time slot, which is a part of a plurality of pre-defined time slots, includes a first frequency resource for downlink and a second frequency resource for uplink, the second frequency resource being different from the first frequency resource , at a common timing, from among the plurality of terminal devices, a first terminal device that performs downlink communication and a second terminal device that performs uplink communication in the first time slot, based on at least one of first information corresponding to a state of a transmission path between each of the plurality of terminal devices and the base station device and second information corresponding to a distance between each of the plurality of terminal devices and the base station device;
a control means for controlling the base station device so as to perform downlink communication with the first terminal device and uplink communication with the second terminal device in the first time slot;
A control device comprising: the first information includes a value indicating a state of a transmission path between each of the plurality of terminal devices and the base station device;
The control device according to claim 1, characterized in that the identification means identifies the first terminal device and the second terminal device so that a correlation value between a value indicating a state of a transmission path for the first terminal device and a value indicating a state of a transmission path for the second terminal device does not exceed a predetermined value. The control device according to claim 2, characterized in that a value indicating the state of the transmission path between each of the plurality of terminal devices and the base station device is obtained based on a sounding reference signal (SRS) transmitted from each of the plurality of terminal devices and received by the base station device. The first information includes a precoding matrix indicator (PMI) for each of the plurality of terminal devices;
2. The control device according to claim 1, wherein the specifying means specifies the first terminal device and the second terminal device such that a PMI related to the first terminal device is different from a PMI related to the second terminal device. The control device according to claim 4, characterized in that the identification means further identifies the first terminal device and the second terminal device such that the difference in direction between a first beam corresponding to the PMI for the first terminal device and a second beam corresponding to the PMI for the second terminal device exceeds a predetermined level. the second information includes a value indicating a distance between each of the plurality of terminal devices and the base station device;
The control device according to any one of claims 1 to 5, characterized in that the identification means identifies the first terminal device and the second terminal device such that the magnitude of the difference between a value indicating a first distance between the first terminal device and the base station device and a value indicating a second distance between the second terminal device and the base station device is greater than or equal to a predetermined threshold. the second information includes a value indicating a received power of a predetermined signal transmitted from the base station device at each of the plurality of terminal devices;
The control device according to any one of claims 1 to 5, characterized in that the identification means identifies the first terminal device and the second terminal device such that the magnitude of the difference between a first received power at the first terminal device and a second received power at the second terminal device is equal to or greater than a predetermined threshold value. The control device according to claim 7, characterized in that the predetermined signal is a reference signal, and the second information includes reference signal received power (RSRP). the second information includes a timing advance (TA) value;
The control device according to any one of claims 1 to 5, characterized in that the identification means identifies the first terminal device and the second terminal device such that the difference between a first TA in the first terminal device and a second TA in the second terminal device is equal to or greater than a predetermined threshold value. The control device according to any one of claims 1 to 9, characterized in that when two communication devices that respectively perform uplink communication and downlink communication are identified and communication is performed without being based on either the first information or the second information, the identification means identifies the first terminal device and the second terminal device based on at least one of the first information and the second information in response to a deterioration in communication quality of the downlink communication. The control device according to any one of claims 1 to 10, characterized in that the identification means, in response to a deterioration in communication quality in the communication in the first terminal device, re-identifies two communication devices that respectively perform uplink communication and downlink communication based on at least one of the first information and the second information. The control device according to claim 10 or 11, characterized in that the determination means determines whether the communication quality has deteriorated based on a success rate of downlink communication in the base station device. The control device according to any one of claims 10 to 12, characterized in that the determination means determines whether the communication quality has deteriorated based on whether there has been a decrease in the communication speed of the downlink communication in the base station device. A control method executed by a control device, comprising:
When a plurality of terminal devices are connected to a base station device that communicates using time division duplexing (TDD) that is pre-configured so that a first time slot, which is a part of a plurality of pre-defined time slots, includes a first frequency resource for downlink and a second frequency resource for uplink, the second frequency resource being different from the first frequency resource, at a common timing , the method identifies, from among the plurality of terminal devices, a first terminal device that performs downlink communication and a second terminal device that performs uplink communication in the first time slot, based on at least one of first information corresponding to a state of a transmission path between each of the plurality of terminal devices and the base station device and second information corresponding to a distance between each of the plurality of terminal devices and the base station device;
controlling the base station device to perform downlink communication with the first terminal device and uplink communication with the second terminal device in the first time slot;
A control method comprising: A computer provided in the control device
When a plurality of terminal devices are connected to a base station device that communicates using time division duplexing (TDD) that is pre-configured so that a first time slot, which is a part of a plurality of pre-defined time slots, includes a first frequency resource for a downlink and a second frequency resource for an uplink, the second frequency resource being different from the first frequency resource , at a common timing , the method identifies, from among the plurality of terminal devices, a first terminal device that performs downlink communication and a second terminal device that performs uplink communication in the first time slot, based on at least one of first information corresponding to a state of a transmission path between each of the plurality of terminal devices and the base station device and second information corresponding to a distance between each of the plurality of terminal devices and the base station device;
controlling the base station device to perform downlink communication with the first terminal device and uplink communication with the second terminal device in the first time slot;
Program for.

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