WO2017104088A1 - Base station, base-station control method, and wireless communication system - Google Patents

Abstract

An eNB (20) includes an offset calculation unit (220) and a wireless-line control unit (222). If an UL/DL configuration of any UE has been changed, the wireless-channel control unit (222) identifies a first subframe that is a subframe set as a downstream section in the UL/DL configuration prior to the change, and that is changed to an upstream section in the UL/DL configuration after the change. The offset calculation unit (220) provides a first UE in which the UL/DL configuration has been changed with an instruction of an initial value of transmission power in the first subframe. In addition, for a second UE, the offset calculation unit (220) calculates the amount of change in reception quality of the first subframe before and after the UL/DL configuration change. In addition, after the first UE has performed transmission in the first subframe using a transmission power corresponding to the initial value, the offset calculation unit (220), on the basis of the amount of change, controls the transmission power of which an instruction is to be provided to the first UE.

Description

Base station, base station control method, and radio communication system

The present invention relates to a base station, a base station control method, and a radio communication system.

A TDD (Time Division Duplex) which has a base station and a terminal, and the base station performs communication by switching between an uplink section for receiving an uplink signal and a downlink section for transmitting a downlink signal in a time division manner with the terminal. ) Type wireless communication system is known. In such a wireless communication system, the base station instructs each terminal of a UL (Up Link) / DL (Down Link) configuration for switching an uplink section and a downlink section in a time division manner for each subframe. The base station instructs each terminal in the cell to have the same UL / DL configuration.

Also, conventionally, since terminals are often used to acquire or view information on the network, the traffic volume in the downlink is larger than the traffic volume in the uplink except for voice communication. Therefore, in the UL / DL configuration instructed from the base station to each terminal, the number of downlink subframes is often set to be larger than the number of uplink subframes.

However, in recent years, with the spread of SNS (Social Networking Service) and the like, the number of users who upload still image and moving image data using a terminal is increasing. For this reason, even in a plurality of terminals existing in the cell of the base station, a terminal having a large uplink data amount and a terminal having a large downlink data amount may coexist. Therefore, it is conceivable to assign a different UL / DL configuration for each terminal according to the usage status of each terminal.

However, assuming that a different UL / DL configuration is assigned to each terminal, the base station may transmit a downlink signal to a certain terminal and receive an uplink signal transmitted from another terminal at the same frequency. is there. In this case, in the base station, the downlink signal transmitted to the terminal wraps around the receiving unit at a high level via the antenna. For this reason, when receiving an uplink signal having the same frequency while transmitting a downlink signal, the quality of the uplink signal received from the terminal deteriorates due to the downlink signal that wraps around the reception unit in the base station.

In order to avoid this, there is known a base station provided with a self-interference canceller that suppresses quality degradation of the uplink signal from the terminal by canceling the downlink signal from the signal received via the antenna. .

US Pat. No. 5,691,978

By the way, assuming that different UL / DL configurations are assigned to each terminal, a base station cell includes a terminal that transmits an uplink signal and a terminal that receives a downlink signal for each subframe. There is a case. In this case, since the transmission of the uplink signal and the reception of the downlink signal are performed in the same subframe using the same frequency, the signal from the terminal that transmits the uplink signal is transmitted to the terminal that receives the downlink signal. Interference signal. Therefore, when a terminal in the vicinity of a terminal that receives a downlink signal transmits an uplink signal, the reception quality of the downlink signal may deteriorate, and the throughput of downlink data may decrease.

The disclosed technology has been made in view of the above, and an object thereof is to suppress a decrease in throughput in a downlink section when a different UL / DL configuration is assigned to each terminal.

In an aspect of the disclosure, a base station that performs communication by switching between an uplink section that receives an uplink signal and a downlink section that transmits a downlink signal in a time-sharing manner with each terminal includes a specifying unit, an instruction unit, And a calculation unit. The identifying unit identifies the first subframe when the switching pattern for switching between the uplink and the downlink in time division is changed for each subframe for any of the terminals. The first subframe is a subframe that is set to the downlink section in the switching pattern before the change and is changed to the uplink section in the switch pattern after the change. The instructing unit instructs an initial value of transmission power in the first subframe to a first terminal that is a terminal whose switching pattern has been changed. For the second terminal that is a terminal other than the first terminal, the calculation unit receives the downlink signal reception quality in the first subframe before the change of the switching pattern and the first subframe after the change of the switching pattern. The amount of change between the reception quality of the downlink signal is calculated. The instructing unit controls the transmission power instructed to the first terminal based on the amount of change after the first terminal transmits with the initial transmission power in the first subframe.

According to the disclosed aspect, it is possible to suppress a decrease in throughput of a downlink section when a different switching pattern is assigned to each terminal.

FIG. 1 is a diagram illustrating an example of a wireless communication system. FIG. 2 is a block diagram illustrating an example of an eNB. FIG. 3 is a diagram for explaining the influence of switching between UL / DL configurations. FIG. 4 is a diagram illustrating an example of control of transmission power of the first UE. FIG. 5 is a diagram illustrating an example of control of transmission power of the first UE. FIG. 6 is a diagram illustrating an example of control of transmission power of the first UE. FIG. 7 is a block diagram illustrating an example of a UE. FIG. 8 is a flowchart illustrating an example of the operation of the eNB. FIG. 9 is a flowchart illustrating an example of the operation of the eNB. FIG. 10 is a sequence diagram illustrating an example of the operation of the wireless communication system. FIG. 11 is a diagram illustrating an example of hardware of a communication device that implements an eNB. FIG. 12 is a diagram illustrating an example of hardware of a communication device that implements a UE.

Hereinafter, embodiments of a base station, a base station control method, and a wireless communication system disclosed in the present application will be described with reference to the drawings. In addition, the base station which this application discloses, the control method of a base station, and a radio | wireless communications system are not limited by the Example shown below.

<Wireless communication system 10>
FIG. 1 is a diagram illustrating an example of a wireless communication system 10. For example, as shown in FIG. 1, the radio communication system 10 includes an eNB (evolved Node B) 20 and a plurality of UEs (User Equipment) 30-1 to 30-n (n is an integer of 2 or more). The eNB 20 performs radio communication with each of the plurality of UEs 30-1 to 30-n in the cell 11 by, for example, the TDD scheme. Hereinafter, a plurality of UEs 30-1 to 30-n are collectively referred to as UE 30 without being distinguished from each other. For convenience of explanation, in FIG. 1, one eNB 20 is provided in the radio communication system 10, but a plurality of eNBs 20 may be provided in the radio communication system 10. The eNB 20 is an example of a base station. Each UE 30 is an example of a terminal.

ENB20 changes UL / DL structure at any time based on the data amount of the uplink signal transmitted from UE30 to eNB20 and the data amount of the downlink signal transmitted from eNB20 to UE30 for every UE30. The UL / DL configuration is information that defines a combination pattern of an uplink subframe and a downlink subframe in one frame. The UL / DL configuration is an example of a switching pattern and an array pattern. Each UE 30 transmits data to the eNB 20 in the uplink subframe and receives data from the eNB 20 in the downlink subframe according to the UL / DL configuration instructed from the eNB 20.

<ENB 20>
FIG. 2 is a block diagram illustrating an example of the eNB 20. The eNB 20 includes, for example, a reception unit 21, a control unit 22, a transmission unit 23, and an antenna 24 as illustrated in FIG. The antenna 24 receives the uplink signal transmitted from the UE 30 and outputs it to the reception unit 21. Moreover, the antenna 24 transmits the downlink signal output from the transmission unit 23 to the UE 30.

The receiving unit 21 includes a quality information extracting unit 210, a control information extracting unit 211, a demodulation / decoding unit 212, a self-interference removing unit 213, and a wireless receiving unit 214. The control unit 22 includes an offset calculation unit 220, a system information management unit 221, and a wireless line control unit 222. The transmission unit 23 includes a control signal generation unit 230, a pilot generation unit 231, a radio channel control information generation unit 232, an encoding / modulation unit 233, a multiple access processing unit 234, a delay unit 235, and a radio transmission unit 236.

<Receiving unit 21>
Radio receiving section 214 performs processing such as down-conversion on the uplink signal output from antenna 24, and outputs the processed uplink signal to self-interference removal section 213.

The self-interference removal unit 213 cancels the downlink signal output from the transmission unit 23 from the uplink signal output from the wireless reception unit 214. Thereby, eNB20 can suppress the quality degradation of the uplink signal received from UE30, even if it is a case where reception of an uplink signal and transmission of a downlink signal are performed simultaneously on the same frequency. The self-interference removing unit 213 outputs the uplink signal from which the downlink signal is canceled to the demodulation / decoding unit 212.

The demodulator / decoder 212 demodulates the uplink signal output from the self-interference canceler 213. Then, the demodulation / decoding unit 212 decodes received data from the demodulated uplink signal. Then, the demodulator / decoder 212 outputs the decoded received data to the core network. The reception data decoded by the demodulation / decoding unit 212 is also output to the quality information extraction unit 210 and the control information extraction unit 211.

The control information extraction unit 211 extracts control information from the reception data output from the demodulation / decoding unit 212. Then, the control information extraction unit 211 outputs the extracted control information to the system information management unit 221. Further, when the extracted control information includes a BSR (Buffer Status Report), the control information extraction unit 211 outputs the BSR to the radio channel control unit 222 together with the information of the UE 30 that is the transmission source of the BSR.

The quality information extraction unit 210 determines whether or not the reception data output from the demodulation / decoding unit 212 includes quality information indicating whether the downlink data has been successfully received or received. The quality information includes ACK (ACKnowledgement) indicating successful reception of data in the downlink section or NACK (Negative ACK) indicating reception failure. When the reception data output from the demodulation / decoding unit 212 includes quality information, the quality information extraction unit 210 includes the information on the UE 30 that is the transmission source of the quality information and the data that is the target of the quality information. The downstream subframe identification information is output to offset calculation section 220.

<Control unit 22>
The system information management unit 221 manages system information for each UE 30 based on the control information output from the quality information extraction unit 210. For example, the system information management unit 221 manages the identification information of the UE 30 in an active state in the cell 11. The UE 30 in the active state is, for example, the UE 30 in RRC (Radio Resource Control) connected mode. In addition, the system information management unit 221 outputs information used to create a pilot signal to the transmission unit 23.

The radio network controller 222 manages the amount of downlink signal data transmitted from the core network side to the UE 30 for each UE 30. Then, the radio network controller 222 determines the UL / DL configuration for each UE 30 based on the data amount of the downlink signal and the BSR output from the quality information extraction unit 210. Further, the radio channel controller 222 determines the reference transmission power P _def in the uplink section of the UL / DL configuration based on the physical resources allocated to the UE 30, the propagation loss between the eNB 20 and the UE 30, and the like. Then, the radio channel control unit 222 outputs the determined UL / DL configuration and reference transmission power P _def information to the radio channel control information creation unit 232 together with the identification information of the UE 30 that is the allocation target of the UL / DL configuration. . In the present embodiment, the radio network controller 222 changes the UL / DL configuration of another UE 30 in the cell 11 for a predetermined period when the UL / DL configuration of any UE 30 in the cell 11 is changed. Do not do. The predetermined period is a period in which, for example, the UE 30 whose UL / DL configuration has been changed is controlling the transmission power offset A in the uplink section.

In addition, when the UL / DL configuration of any UE 30 in the cell 11 is changed, the radio network controller 222 determines whether or not there is a first subframe in the changed UL / DL configuration. The first subframe is a subframe that is designated as the downlink section in the UL / DL configuration before the change and is designated as the uplink section in the UL / DL configuration after the change. The subframe specified for the uplink section is an example of an uplink section subframe, and the first subframe is an example of a specific uplink section subframe. Below, UE30 by which UL / DL structure was changed is called 1st UE30. The first UE 30 is an example of a first terminal.

When there is a first subframe in the UL / DL configuration after the change, the radio network controller 222 determines that another UE 30 to which the UL / DL configuration in which the first subframe is a downlink section is assigned is the cell 11 is present or not. Hereinafter, another UE 30 to which the UL / DL configuration in which the first subframe is a downlink section is assigned is referred to as a second UE 30. The second UE 30 is an example of a second terminal.

When the second UE 30 is present in the cell 11, the radio network controller 222, the first subframe information, the first UE 30 identification information, the second UE 30 identification information, Information on the reference transmission power P _def of UE 30 is output to offset calculation section 220. In addition, when the instruction to restore the UL / DL configuration is output from the offset calculation unit 220, the radio network controller 222 changes the UL / DL configuration of the first UE 30 to the UL / DL configuration before the change. return. The wireless line control unit 222 is an example of a control unit and a specifying unit.

Here, the effect when the UL / DL configuration is changed will be described. FIG. 3 is a diagram for explaining the influence of switching between UL / DL configurations. 3A to 3C show the UL / DL configuration for one frame. One frame includes 10 subframes # 0 to # 9. 3A to 3C, “D” indicates a subframe in a downstream section, “U” indicates a subframe in an upstream section, and “S” indicates a special subframe.

When the UL / DL configuration of the second UE 30 is, for example, the UL / DL configuration illustrated in FIG. 3C, the UL / DL configuration of the first UE 30 is, for example, the UL / DL configuration illustrated in FIG. For example, a case where the UL / DL configuration shown in FIG. In the UL / DL configuration shown in FIG. 3A and the UL / DL configuration shown in FIG. 3B, the allocation of subframes # 6 to 9 is different. Also, the subframes # 7 to # 9 are changed from the downlink section to the uplink section. In the example of FIG. 3, the subframes # 7 to # 9 are the first subframe. In the first subframe, the subframe set in the downlink section in the UL / DL configuration of the second UE 30 is, for example, the subframe # 9 as shown in FIG.

For example, as shown in FIG. 3B, the first UE 30 transmits an uplink signal to the eNB 20 in the first subframes # 7 to # 9. For example, as shown in FIG. 3C, the second UE 30 receives the downlink signal from the eNB 20 in the subframe # 9 in the first subframe # 7 to # 9. Therefore, when the UL / DL configuration is changed, the uplink signal transmitted from the first UE 30 in the subframe # 9 may newly give interference to the second UE 30. When the distance between the first UE 30 and the second UE 30 is short, the second UE 30 may fail to receive the downlink signal due to the uplink signal transmitted from the first UE 30. Thereby, the throughput of the downlink section in the 2nd UE30 may fall.

Therefore, the eNB 20 of this embodiment controls the transmission power of the first UE 30 in the first subframe so that the transmission power is lower than the reference transmission power P _def by an offset A. That is, in the changed UL / DL configuration, the transmission power applied to the signal transmitted in the first subframe and the subframe specified in the uplink section other than the first subframe are transmitted. An offset is set between the transmission power applied to the signal. Thereby, the reception failure of the downlink signal by the second UE 30 can be suppressed, and a decrease in the throughput of the downlink section can be suppressed. When changing the UL / DL configuration applied to the first UE 30, the eNB 20 may notify the first UE 30 of information specifically indicating which subframe the offset A is applied to. . At this time, when the unit of UL / DL configuration is m subframes (when one UL / DL configuration pattern is repeated every m subframes), an offset A application target is determined using a bitmap of length m. Can be shown. The eNB 20 may transmit this bitmap to the first UE 30 together with information indicating the change contents of the UL / DL configuration. Moreover, eNB20 may notify the value of offset A to UE30 by including the value of offset A in the control signal used in order to give permission of signal transmission with respect to UE30.

Moreover, eNB20 of a present Example monitors the NACK incidence rate of 2nd UE30 about the downlink signal of a 1st sub-frame, and transmission power of 1st UE30 in a 1st sub-frame based on this NACK occurrence rate To control. Specifically, the eNB 20 changes the NACK occurrence rate of the second UE 30 after the UL / DL configuration is changed with reference to the NACK occurrence rate of the second UE 30 before the UL / DL configuration is changed. The transmission power of the first UE 30 is controlled so that the amount is less than a predetermined value. Thereby, eNB20 can suppress the fall of the throughput of 2nd UE30 in a downlink area.

Moreover, eNB20 controls the transmission power of 1st UE30 so that the transmission power of 1st UE30 may become large in the range from which the variation | change_quantity of the NACK incidence rate of 2nd UE30 will be less than predetermined value. Thereby, the throughput of the up section in 1st UE30 can be improved. Note that, for example, as illustrated in FIG. 3B, the first UE 30 transmits an uplink signal with the reference transmission power P _def for the subframes in the uplink section other than the first subframe.

Returning to FIG. 2, the description will be continued. The offset calculation unit 220, when information such as the first subframe is output from the radio channel control unit 222, the initial value A ₀ of the offset A of the transmission power output by the first UE 30 in the first subframe. Is calculated.

The offset calculation unit 220 calculates the initial value of the transmission power P of the first UE 30 in the first subframe based on the area of the cell 11 of the eNB 20 and the number of UEs 30 in the cell 11. For example, the offset calculation unit 220 determines whether the UEs 30 in the active state are evenly distributed in the cell 11 based on the number of UEs 30 in the cell 11 and the area of the cell 11. Calculate the average distance. Then, the offset calculation unit 220 assumes that the first UE 30 and the second UE 30 are adjacent to each other at the calculated average distance, and the upstream of the first UE 30 is within a range in which the NACK occurrence rate of the second UE 30 does not deteriorate. The maximum value P _max of the signal transmission power is calculated. The maximum value P _max is an example of the initial value of the transmission power P of the first UE 30 in the first subframe. Then, the offset calculation unit 220 calculates the difference between the reference transmission power P _def calculated by the radio channel control unit 222 and the aforementioned maximum value P _max as the initial value A ₀ of the offset A. Then, the offset calculation unit 220 outputs the calculated initial value A ₀ of the offset A to the transmission unit 23 together with the information of the first subframe and the identification information of the first UE 30. The maximum value P _max is, if the reference is greater than the transmission power P _def equal to or reference transmission power P _def, the initial value A ₀ is 0 offset A. The initial value A ₀ of the offset A may be notified to the first UE 30 together with the UL / DL configuration information when the UL / DL configuration is changed.

Also, the offset calculation unit 220 calculates the NACK occurrence rate for each subframe for each UE 30 based on the quality information output from the control information extraction unit 211. The NACK occurrence rate is an example of reception quality. Further, when the UL / DL configuration of any UE 30 is changed, the offset calculation unit 220 calculates the difference between the NACK occurrence rate R ₁ of the second UE 30 and the NACK occurrence rate R ₂ of the second UE 30. Calculated as a change amount ΔR. The NACK occurrence rate R ₁ is the NACK occurrence rate of the first subframe before the UL / DL configuration change, and the NACK occurrence rate R ₂ is the NACK occurrence of the first subframe after the UL / DL configuration change. is the rate R _2. For example, the offset calculator 220 calculates a value obtained by subtracting the NACK occurrence rate R ₁ from the NACK occurrence rate R ₂ as the change amount ΔR.

The offset calculation unit 220, after the UL / DL configuration is changed, for example, every several frames, calculates the NACK occurrence rate R ₂ of the first sub-frame after the change of the UL / DL configurations. Then, the offset calculation unit 220 updates the change amount ΔR using the calculated NACK occurrence rate R ₂ and the NACK occurrence rate R ₁ .

When the change amount ΔR is greater than or equal to the first threshold value R _th1, that is, when the NACK occurrence rate of the second UE 30 is greatly deteriorated due to the UL / DL configuration change, the offset calculation unit 220 changes the offset A to a predetermined change The transmission power P of the first UE 30 when the amount is increased by the amount ΔA ₁ is calculated. If the offset A is increased change amount .DELTA.A ₁ minute, the transmission power P of the first UE30 is decreased change amount .DELTA.A ₁ minute. The change amount ΔA ₁ of the offset A is an example of an instruction to reduce the transmission power by the first power.

When the calculated transmission power P is greater than the predetermined lower limit value P _th , the offset calculating unit 220 outputs the calculated change amount ΔA ₁ of the offset A to the control signal generating unit 230 together with the identification information of the first UE 30. To do. The calculated change amount ΔA ₁ of the offset A is transmitted to the first UE 30. Thereby, the transmission power of the first UE 30 in the first subframe is decreased by the change amount ΔA ₁ , and the NACK occurrence rate of the second UE 30 in the first subframe is improved. The lower limit value P _th is an example of a third threshold value.

On the other hand, when the calculated transmission power P is equal to or lower than the lower limit value P _th , the offset calculation unit 220 outputs an instruction to restore the UL / DL configuration to the radio line control unit 222. And the offset calculation part 220 complete | finishes the process which controls the offset A of 1st UE30.

When the change amount ΔR is less than the second threshold value R _th2, that is, when the width of the deterioration of the NACK occurrence rate of the second UE 30 is small, the offset calculation unit 220 changes the offset A to the predetermined change amount ΔA _2. The transmission power P of the first UE 30 when it is decreased by a certain amount is calculated. If the offset A is decreased change amount .DELTA.A ₂ minutes, the transmission power P of the first UE30 increases change amount .DELTA.A ₂ minutes. Note that the second threshold value R _th2 is lower than the first threshold value R _th1 .

When the calculated transmission power P is greater than or equal to the reference transmission power P _def , the offset calculation unit 220 sets the difference between the current transmission power P of the first UE 30 and the reference transmission power P _def as the change amount ΔA ₂ ′. calculate. Then, the calculated change amount ΔA ₂ ′ of the offset A is output to the control signal creation unit 230 together with the identification information of the first UE 30, and the process of controlling the offset A of the first UE 30 is ended. The calculated change amount ΔA ₂ ′ of offset A is transmitted to the first UE 30. Thus, the transmission power of the first UE30 in the first sub-frame is increased to the reference transmission power P _def.

On the other hand, when the calculated transmission power P is lower than the reference transmission power P _def , the offset calculation unit 220 outputs the calculated change amount ΔA ₂ of the offset A to the transmission unit 23 together with the identification information of the first UE 30. . The calculated change amount ΔA ₂ of the offset A is transmitted to the first UE 30. Thereby, the transmission power P of the first UE 30 in the first subframe is increased by the change amount ΔA ₂ , and the throughput of the uplink signal of the first UE 30 in the first subframe is improved. The change amount ΔA ₂ and the change amount ΔA ₂ ′ of the offset A are an example of an instruction for increasing the transmission power by the second power. Note that the absolute value of the change amount ΔA _{1 and} the absolute value of the change amount ΔA ₂ may be the same size or different sizes.

Further, when the change amount ΔR is less than the first threshold value R _th1 and equal to or more than the second threshold value R _th2 , the offset calculation unit 220 does not change the offset A of the first UE 30. In this case, the fact that the offset change amount is 0 may be indicated in the control signal transmitted to the first UE 30. And when the period which does not change the offset A of the 1st UE30 continues more than predetermined time, the offset calculation part 220 complete | finishes the process which controls the offset A of the 1st UE30. The predetermined time is, for example, a time for several frames. The value of the predetermined time may be notified to the first UE 30 together with the UL / DL configuration information when the UL / DL configuration is changed. Or the value of this predetermined time may be alert | reported to each eNB20 as common information by eNB20, and may be used as a value common among all UE30 which communicates with eNB20. Further, after a predetermined time has elapsed since the offset A value notified from the eNB 20 is applied to the transmission power of the UE 30, the offset A value becomes invalid or becomes zero at the UE 30. May be. Thereby, after the predetermined time has elapsed since the value of the offset A notified from the eNB 20 is applied to the transmission power of the UE 30, the transmission power of the UE 30 returns to the normal transmission power.

Note that, when there are a plurality of second UEs 30 in the cell 11, the offset calculation unit 220 calculates the change amount ΔR for each second UE 30 and, for example, the largest value among the calculated change amounts ΔR. Is determined. Then, using the specified change amount ΔR, the offset calculation unit 220 determines whether the change amount ΔR is greater than or equal to the first threshold value R _th1 and whether the change amount ΔR is greater than or equal to the second threshold value R _th2. judge. The offset calculation unit 220 is an example of an instruction unit and a calculation unit.

<Transmitter 23>
The control signal generator 230 outputs the first subframe output from the offset calculator 220, the initial value A ₀ of the offset A, the change amount ΔA ₁ , the change amount ΔA ₂ , the change amount ΔA ₂ ′, and the effective period of the offset value. A control signal including one or a plurality of pieces of information such as the first UE 30 is created. Then, the control signal creation unit 230 outputs the created control signal to the encoding / modulation unit 233.

The pilot creation unit 231 creates a pilot signal based on the information output from the system information management unit 221, and outputs the created pilot signal to the encoding / modulation unit 233.

The radio channel control information creation unit 232 includes, together with the identification information of the UE 30, one or more of the UL / DL configuration, information indicating a subframe to which the transmission power offset is applied, information on the reference transmission power P _def , and the like. When output from the radio channel controller 222, radio channel control information including these pieces of information and destined for the UE 30 is created. Radio channel control information creation section 232 then outputs the created radio channel control information to encoding / modulation section 233.

The encoding / modulation unit 233 outputs the transmission data output from the core network, the control signal output from the control signal generation unit 230, the pilot signal output from the pilot generation unit 231 and the radio channel control information generation unit 232 The obtained radio channel control information is encoded. The control signal output from control signal generator 230 and the radio channel control information output from radio channel control information generator 232 may be transmitted independently of each other at the same time or independently of each other at different times. It doesn't matter. Then, the encoding / modulation unit 233 modulates the encoded downlink signal and outputs the modulated downlink signal to the multiple access processing unit 234.

The multiple access processing unit 234 maps the downlink signal to each UE 30 to a physical resource. Then, the multiple access processing unit 234 outputs the mapped downlink signal to the delay unit 235 and the wireless transmission unit 236. The delay unit 235 delays the downlink signal output from the multiple access processing unit 234 by a predetermined time and outputs the delayed signal to the self-interference removal unit 213.

The radio transmission unit 236 performs processing such as up-conversion on the downlink signal output from the multiple access processing unit 234, and transmits the processed downlink signal via the antenna 24.

<Control of transmission power of first UE 30>
4 to 6 are diagrams illustrating an example of transmission power control of the first UE 30. FIG. For example, FIG. 4 shows the offset A and the transmission power P of the first UE 30 when the fluctuation amount ΔR of the NACK occurrence rate of the second UE 30 is equal to or greater than the first threshold R _th1 due to the change in the UL / DL configuration. To change. FIG. 4B shows a change in the transmission power P of the first UE 30 in the first subframe.

First, the offset calculation unit 220 at time t _0, for example, as shown in FIG. 4 (a), to calculate the initial value A ₀ of the offset A. Information on the initial value A ₀ of the offset A is notified to the first UE 30. As a result, the first UE 30 starts transmission of the uplink signal at time t _{0 with} power P ₀ that is lower than the reference transmission power P _def by the initial value A ₀ , for example, as shown in FIG. 4B.

Thereafter, at time t ₁ when the amount of change ΔR of the NACK occurrence rate of the second UE 30 becomes equal to or greater than the first threshold R _th1 , the offset calculation unit 220 sets the offset A as shown in FIG. Increase from the initial value A ₀ by the change amount ΔA ₁ . Thereby, the first UE 30 decreases the transmission power P of the uplink signal by the change amount ΔA ₁ from the power P _{0 at} time t ₁ , for example, as illustrated in FIG. 4B. In this way, every time the change amount ΔR of the NACK occurrence rate of the second UE 30 becomes equal to or greater than the first threshold R _th1 , the offset calculation unit 220 increases the offset A by the change amount ΔA ₁ , and the first UE 30 The transmission power P decreases by the change amount ΔA ₁ .

Then, by increasing the offset A by the change amount ΔA ₁ , the offset calculation unit 220 restores the UL / DL configuration to the original at time t ₂ when the transmission power P of the first UE 30 is equal to or lower than the lower limit value P _th. An instruction to that effect is output to the radio network controller 222. Thereby, the UL / DL configuration of the first UE 30 is restored. And the offset calculation part 220 complete | finishes the process which controls the offset A of 1st UE30.

The offset A and the transmission power P of the first UE 30 when the fluctuation amount ΔR of the NACK occurrence rate of the second UE 30 becomes less than the second threshold R _th2 due to the UL / DL configuration change are shown in FIG. To change. FIG. 5B shows a change in the transmission power P of the first UE 30 in the first subframe.

First, the offset calculation unit 220 at time t _0, for example, as shown in FIG. 5 (a), to calculate the initial value A ₀ of the offset A, first UE30 at time t _0, for example, FIG. 5 ( As shown in b), uplink signal transmission is started at power P ₀ .

Thereafter, at time t ₁ when the change amount ΔR of the NACK occurrence rate of the second UE 30 becomes less than the second threshold value R _th2 , the offset calculation unit 220 sets the offset A as shown in FIG. Decrease the change amount ΔA ₂ from the initial value A ₀ . As a result, the first UE 30 increases the transmission power P of the uplink signal by the change amount ΔA ₂ from the power P _{0 at} time t ₁ , for example, as illustrated in FIG. 5B. In this way, every time the change amount ΔR of the NACK occurrence rate of the second UE 30 becomes less than the second threshold R _th2 , the offset calculation unit 220 decreases the offset A by the change amount ΔA ₂ , and the first UE 30 Transmission power P increases by a change amount ΔA ₂ .

Then, by reducing the offset A by the change amount ΔA _2, at time t _{2 when} the transmission power P of the first UE 30 becomes equal to or higher than the reference transmission power P _def , the offset calculation unit 220 calculates the current offset A value. It is calculated as the change amount ΔA ₂ ′ of the offset A. The change amount ΔA ₂ ′ corresponds to the difference between the current transmission power P ′ and the reference transmission power P _def . Information on the change amount ΔA ₂ ′ is notified to the first UE 30. Thus, the first UE30, at time t _2, the example as shown in FIG. 5 (b), the transmission power P of the uplink signal is increased change amount .DELTA.A ₂ 'min. Thereby, the transmission power P of the first UE 30 becomes the reference transmission power P _def . And the offset calculation part 220 complete | finishes the process which controls the offset A of 1st UE30. Thereafter, the first UE30 is a reference transmission power P _def, transmits an uplink signal in the first subframe.

The offset A and the transmission power of the first UE 30 when the fluctuation amount ΔR of the NACK occurrence rate of the second UE 30 becomes between the first threshold R _th1 and the second threshold R _th2 due to the change of the UL / DL configuration. P changes, for example, as shown in FIG. FIG. 6B shows a change in the transmission power P of the first UE 30 in the first subframe.

First, the offset calculation unit 220 at time t _0, for example, as shown in FIG. 6 (a), to calculate the initial value A ₀ of the offset A, first UE30 at time t _0, for example, FIG. 6 ( As shown in b), uplink signal transmission is started at power P ₀ .

Thereafter, in accordance with the change amount ΔR of the NACK occurrence rate of the second UE 30, the offset calculation unit 220 increases the offset A by the change amount ΔA ₁ or changes the change amount ΔA ₂ minutes, for example, as shown in FIG. Decrease. Accordingly, the first UE 30 decreases the transmission power P of the uplink signal by the change amount ΔA ₁ or increases the change amount ΔA ₂ as shown in FIG. 6B, for example. Then, at the time t _{1 when the} period during which the offset A is not changed continues for the predetermined time ΔT or more, the offset calculation unit 220 ends the process of controlling the offset A of the first UE 30. Thereafter, the first UE 30 transmits the uplink signal in the first subframe with the transmission power P at time t ₁ .

<UE30>
FIG. 7 is a block diagram illustrating an example of the UE 30. For example, as illustrated in FIG. 7, the UE 30 includes a reception unit 31, a control unit 32, a transmission unit 33, and an antenna 34. The antenna 34 receives the downlink signal transmitted from the eNB 20 and outputs it to the reception unit 31. Further, the antenna 34 transmits the uplink signal output from the transmission unit 33 to the eNB 20.

The reception unit 31 includes a radio reception unit 310, a demodulation / decoding unit 311, a system information extraction unit 312, a control signal extraction unit 313, a pilot extraction unit 314, and a channel quality measurement unit 315. The control unit 32 includes a terminal information control unit 320, a system information management unit 321, and a wireless line control unit 322. The transmission unit 33 includes a radio transmission unit 330, an encoding / modulation unit 331, a pilot creation unit 332, a control signal creation unit 333, and a radio channel control information creation unit 334.

<Receiver 31>
The wireless reception unit 310 performs a reception operation in accordance with control from the wireless line control unit 322. Radio receiving section 310 performs processing such as down-conversion on the downlink signal output from antenna 34 in the receiving operation, and outputs the processed downlink signal to demodulation / decoding section 311.

The demodulation / decoding unit 311 demodulates the downlink signal output from the wireless reception unit 310. Then, the demodulation / decoding unit 311 decodes received data from the demodulated downlink signal. Then, the demodulation / decoding unit 311 outputs the decoded received data to an application processing unit (not shown) that performs processing based on the received data. The reception data decoded by the demodulation / decoding unit 311 is also output to the system information extraction unit 312, the control signal extraction unit 313, and the pilot extraction unit 314.

The system information extraction unit 312 extracts system information from the reception data output from the demodulation / decoding unit 311. Then, the system information extraction unit 312 outputs the extracted system information to the system information management unit 321.

The control signal extraction unit 313 extracts radio channel control information and control signals from the received data output from the demodulation / decoding unit 311. Then, the control signal extraction unit 313 extracts information on the UL / DL configuration and the reference transmission power P _def from the extracted radio channel control information and outputs the information to the radio channel control unit 322. Further, the control signal extraction unit 313 extracts the first subframe, the initial value A ₀ of the offset A, the change amount ΔA ₁ , the change amount ΔA ₂ , and the change amount ΔA ₂ ′ from the extracted control signal. The data is output to the wireless line control unit 322. Further, the control signal extraction unit 313 outputs information indicating whether the demodulation / decoding unit 311 has successfully decoded received data to the line quality measurement unit 315.

Pilot extraction section 314 extracts a pilot signal from the reception data output from demodulation / decoding section 311. Then, pilot extraction section 314 outputs the extracted pilot signal to channel quality measurement section 315.

The channel quality measurement unit 315 measures the quality of the radio channel based on the pilot signal output from the pilot extraction unit 314. Also, the channel quality measurement unit 315 acquires information indicating whether or not the received data has been successfully decoded from the control signal extraction unit 313, and creates ACK or NACK information for each subframe in the downlink section. Then, channel quality measuring section 315 outputs ACK or NACK information generated for each subframe to radio channel control information creating section 334.

<Control unit 32>
The terminal information control unit 320 monitors the data amount in the transmission buffer of the UE 30 and creates a BSR indicating the data amount in the transmission buffer. Terminal information control unit 320 then outputs the created BSR to radio channel control unit 322.

The system information management unit 321 manages the system information output from the system information extraction unit 312. Then, system information management section 321 outputs information used for generating a pilot signal to pilot creation section 332.

When the BSR is output from the terminal information control unit 320, the radio line control unit 322 outputs the BSR information to the control signal creation unit 333. Further, based on the UL / DL configuration output from the control signal extraction unit 313, the radio line control unit 322 instructs the radio reception unit 310 to perform a reception operation in the subframe in the downlink section, and performs radio communication in the subframe in the uplink section. A transmission operation is instructed to the transmission unit 330.

In addition, when the control signal extraction unit 313 outputs the reference transmission power P _def , the first subframe, and the information about the initial value A ₀ of the offset A, the radio channel control unit 322 outputs the reference transmission power P _def. Then, the power obtained by subtracting the initial value A ₀ is calculated as the initial value P ₀ of the transmission power P. Then, the wireless channel control unit 322 controls the wireless transmission unit 330 to transmit the uplink signal in the first subframe with the calculated initial value P ₀ of the transmission power P.

Further, when the change amount ΔA ₁ is output from the control signal extraction unit 313, the radio line control unit 322 decreases the transmission power P in the first subframe from the current transmission power P by the change amount ΔA _1. To the wireless transmission unit 330. Further, when the change amount ΔA ₂ or the change amount ΔA ₂ ′ is output from the control signal extraction unit 313, the radio line control unit 322 changes the transmission power P in the first subframe from the current transmission power to the change amount ΔA. _The wireless transmission unit 330 is controlled to increase by ₂ or the change amount ΔA ₂ ′.

In addition, when no change amount ΔA ₁ , ΔA ₂ , or ΔA ₂ ′ is output from the control signal extraction unit 313 for a predetermined time or longer, the wireless line control unit 322 changes the change amount ΔA ₁ , ΔA ₂ , or ΔA. The control of the transmission power P in the first subframe based on ₂ ′ is terminated.

<Transmitter 33>
The radio channel control information creation unit 334 creates radio channel control information including ACK or NACK information output from the channel quality measurement unit 315. Radio channel control information creation section 334 then outputs the created radio channel control information to encoding / modulation section 331. The control signal creation unit 333 creates a control signal including the BSR output from the wireless line control unit 322. Then, the control signal creation unit 333 outputs the created control signal to the encoding / modulation unit 331. The pilot creation unit 332 creates a pilot signal using information output from the system information management unit 321. Then, pilot creation section 332 outputs the created pilot signal to encoding / modulation section 331.

The encoding / modulation unit 331 encodes transmission data output from an application processing unit (not shown) to generate an uplink signal. Also, the encoding / modulation unit 331 receives the pilot signal output from the pilot generation unit 332, the control signal output from the control signal generation unit 333, and the radio channel control information output from the radio channel control information generation unit 334. The upstream signal is generated by encoding. Then, the encoding / modulation unit 331 modulates the encoded uplink signal and outputs the modulated uplink signal to the radio transmission unit 330.

The wireless transmission unit 330 performs a transmission operation in accordance with control from the wireless line control unit 322. The wireless transmission unit 330 performs processing such as up-conversion on the uplink signal output from the encoding / modulation unit 331 in the transmission operation. Then, the wireless transmission unit 330 transmits the processed uplink signal with the transmission power P instructed from the wireless line control unit 322 via the antenna 34.

<Operation of eNB 20>
8 and 9 are flowcharts illustrating an example of the operation of the eNB 20. The eNB 20 starts the operation illustrated in FIG. 8 at a predetermined timing after activation, for example. In addition to the flowchart shown in FIG. 8, the offset calculation unit 220 of the eNB 20 calculates the NACK occurrence rate for each subframe for each UE 30 at a predetermined timing.

First, the radio network controller 222 determines whether to change the UL / DL configuration for each UE 30 (S100). Whether or not the radio network controller 222 changes the UL / DL configuration for each UE 30 based on, for example, the amount of downlink signal data transmitted from the core network side to the UE 30 and the BSR transmitted from the UE 30. Determine. If it is determined that the UL / DL configuration is not to be changed (S100: No), the wireless line control unit 222 executes the process shown in step S100 again.

When it is determined that the UL / DL configuration is to be changed (S100: Yes), the radio network controller 222 determines the UL / DL after the change based on the data amount of the downlink signal and the BSR output from the quality information extraction unit 210. Determine the DL configuration. Further, the radio network controller 222 determines the reference transmission power P _def of the UE 30 that changes the UL / DL configuration.

Next, when the UL / DL configuration of any UE 30 in the cell 11 is changed, the radio network controller 222 specifies the first subframe in the changed UL / DL configuration (S101). Then, the radio network controller 222 determines whether or not the second UE 30 to which the UL / DL configuration in which the first subframe is a downlink section is assigned exists in the cell 11 (S102). .

When the second UE 30 does not exist (S102: No), the radio network controller 222 outputs the changed UL / DL configuration and reference transmission power P _def together with the identification information of the first UE 30 to the transmitter 23. . The transmission unit 23 transmits information on the UL / DL configuration and the reference transmission power P _def to the first UE 30 (S106). Then, the wireless line control unit 222 executes the process shown in step S100 again.

On the other hand, when the second UE 30 exists (S102: Yes), the eNB 20 starts a process of controlling the offset A of the first UE 30. Specifically, the radio network controller 222 outputs the changed UL / DL configuration and reference transmission power P _def together with the identification information of the first UE 30 to the transmitter 23. Then, the radio network controller 222 obtains information on the first subframe, identification information on the first UE 30, identification information on the second UE 30, and information on the reference transmission power P _def of the first UE 30. Output to the offset calculator 220. The offset calculation unit 220 stores the NACK occurrence rate R ₁ of the second UE 30 before the UL / DL configuration is changed for the first subframe (S103).

Next, the offset calculation unit 220 calculates an initial value A ₀ of the offset A applied to the transmission power P of the uplink signal transmitted by the first UE 30 in the first subframe (S104). Then, the offset calculation unit 220 outputs the calculated initial value A ₀ of the offset A to the transmission unit 23 together with the information of the first subframe and the identification information of the first UE 30. The transmitter 23 transmits the changed UL / DL configuration, the first subframe, the initial value A ₀ of the offset A, and the information of the reference transmission power P _def to the first UE 30 (S105).

Next, the offset calculation unit 220 resets and starts the timer (S107 in FIG. 9). Then, the offset calculation unit 220 calculates the NACK occurrence rate R ₂ of the first subframe after the UL / DL configuration change for the second UE 30 based on the quality information output from the control information extraction unit 211. (S108). Then, the offset calculation unit 220 calculates, as the change amount ΔR, a value obtained by subtracting the NACK occurrence rate R ₁ stored in step S103 from the NACK occurrence rate R ₂ calculated in step S108 (S109).

Next, the offset calculation unit 220 determines whether or not the amount of change ΔR is greater than or equal to the first threshold R _th1 (S110). If the change amount ΔR is the first threshold value R _th1 or more (S110: Yes), offset calculation section 220 calculates the transmission power P of the first UE30 the case of increasing the offset A change amount .DELTA.A ₁ minute (S111). Increasing the offset A change amount .DELTA.A ₁ minute, the transmission power P of the first UE30 is decreased change amount .DELTA.A ₁ minute. The offset calculation unit 220 determines whether or not the calculated transmission power P is less than or equal to the lower limit value P _th (S112).

When the calculated transmission power P is equal to or lower than the lower limit value P _th (S112: Yes), the offset calculation unit 220 outputs an instruction to restore the UL / DL configuration to the radio channel control unit 222, and the eNB 20 The process for controlling the offset A of the first UE 30 is terminated. The radio network controller 222 restores the UL / DL configuration of the first UE 30 (S113). Then, the wireless line control unit 222 executes the process shown in step S100 in FIG. 8 again.

On the other hand, if the calculated transmit power P is larger than the lower limit value P _th (S112: No), offset calculation section 220, a change amount .DELTA.A ₁ offset A, output to the transmission section 23 together with the identification information of the first UE30 To do. The transmission unit 23 transmits the change amount ΔA ₁ of the offset A to the first UE 30 (S114). As a result, the transmission power P of the first UE 30 in the first subframe decreases by the change amount ΔA ₁ . And the offset calculation part 220 performs the process shown to step S107 again.

When the change amount ΔR is less than the first threshold value R _th1 (S110: No), the offset calculation unit 220 determines whether or not the change amount ΔR is less than the second threshold value R _th2 (S115). If the amount of change ΔR is less than the second threshold value R _th2 (S115: Yes), offset calculation section 220 calculates the transmission power P of the first UE30 when reduced offset A change amount .DELTA.A ₂ minutes (S116). Reducing the offset A change amount .DELTA.A ₂ minutes, the transmission power P of the first UE30 increases change amount .DELTA.A ₂ minutes. Then, the offset calculation unit 220 determines whether or not the calculated transmission power P is greater than or equal to the reference transmission power P _def (S117).

When the calculated transmission power P is greater than or equal to the reference transmission power P _def (S117: Yes), the offset calculation unit 220 calculates the current offset A value as the offset A change amount ΔA ₂ ′. The change amount ΔA ₂ ′ corresponds to the difference between the current transmission power P ′ and the reference transmission power P _def . The offset calculation unit 220, a change amount .DELTA.A ₂ 'of the calculated offset A, and outputs to the transmission section 23 together with the identification information of the first UE 30, and terminates the process of controlling the offset A of the first UE 30 . The transmission unit 23 transmits the change amount ΔA ₂ ′ of the offset A to the first UE 30 (S118). Thus, the transmission power P of the first UE30 in the first sub-frame is increased to the reference transmission power P _def. Then, the wireless line control unit 222 executes the process shown in step S100 in FIG. 8 again.

On the other hand, when the calculated transmission power P is less than the reference transmission power P _def (S117: No), the offset calculation unit 220 transmits the change amount ΔA ₂ of the offset A together with the identification information of the first UE 30 to the transmission unit 23. Output to. The transmission unit 23 transmits the change amount ΔA ₂ of the offset A to the first UE 30 (S119). As a result, the transmission power P of the first UE 30 in the first subframe increases by the change amount ΔA ₂ . And the offset calculation part 220 performs the process shown to step S107 again.

When the change amount ΔR is equal to or greater than the second threshold value R _th2 (S115: No), the offset calculation unit 220 determines whether or not the timer value is equal to or greater than a value indicating the predetermined time ΔT (S120). When the value of the timer is equal to or greater than the value indicating the predetermined time ΔT (S120: Yes), the offset calculation unit 220 ends the process of controlling the offset A of the first UE 30. Then, the wireless line control unit 222 executes the process shown in step S100 in FIG. 8 again. On the other hand, when the value of the timer is less than the value indicating the predetermined time ΔT (S120: No), the offset calculation unit 220 executes the process shown in step S108 again.

<Operation of Wireless Communication System 10>
FIG. 10 is a sequence diagram illustrating an example of the operation of the wireless communication system 10. In the example of FIG. 10, the UE 30-1 is the first UE 30 and the UE 30-2 is the second UE 30.

First, the UE 30-1 transmits a BSR to the eNB 20 (S200). When the eNB 20 decides to change the UL / DL configuration of the UE 30-1, the information about the changed UL / DL configuration, the first subframe, the reference transmission power P _def , and the initial value A ₀ of the offset A is transmitted to the UE 30-1. -1 (S201).

The UE 30-1 resets and starts the timer (S202), and transmits a transmission request to the eNB 20 (S203). The eNB 20 transmits a transmission permission to the UE 30-1 (S204). Thereafter, the UE 30-1 starts data transmission in the uplink subframe in the UL / DL configuration after the change transmitted from the eNB 20 in step S201 (S205). Note that the UE 30-1 starts uplink signal transmission with power lower by the initial value A _{0 of the} offset A than the reference transmission power P _{def in} the section of the first subframe in the UL / DL configuration after the change.

After the UL / DL configuration of the UE 30-1 is changed, the eNB 20 receives the ACK or NACK information transmitted from the UE 30-2 (S206), and calculates the change amount ΔR of the NACK occurrence rate. Then, the eNB 20 calculates the change amount ΔA of the offset A based on the change amount ΔR of the NACK occurrence rate (S207). When the change amount ΔR of the NACK occurrence rate is equal to or greater than the first threshold value R _th1 , the eNB 20 transmits the change amount ΔA ₁ to the UE 30-1, and the change amount ΔR of the NACK occurrence rate is less than the second threshold value R _th2 If there is, the change amount ΔA ₂ is transmitted to the UE 30-1 (S208). Then, the UE 30-1 resets and starts the timer (S209). And eNB20, UE30-1, and UE30-2 perform the process after step S203 again.

<Effect of Example>
As is clear from the above description, the eNB 20 of this embodiment includes an offset calculation unit 220 and a radio channel control unit 222. When the UL / DL configuration of any UE 30 is changed, the radio network controller 222 is set to the downlink section in the UL / DL configuration before the change, and is changed to the uplink section in the UL / DL configuration after the change. A first subframe that is a subframe is identified. The offset calculation unit 220 instructs the initial value of the transmission power in the first subframe to the first UE 30 that is the UE 30 whose UL / DL configuration has been changed. In addition, for the second UE 30, the offset calculation unit 220 receives the downlink signal reception quality in the first subframe before the UL / DL configuration change and the downlink in the first subframe after the UL / DL configuration change. The amount of change between the reception quality of the signal is calculated. In addition, after the first UE 30 performs transmission with the initial transmission power in the first subframe, the offset calculation unit 220 controls the transmission power instructed to the first UE 30 based on the amount of change. Thereby, when assigning a different UL / DL configuration for each UE 30, it is possible to suppress a decrease in throughput in the downlink section.

In addition, the offset calculation unit 220 determines that the second UE 30 has failed to receive the downlink signal before the UL / DL configuration is changed, and the second UE 30 receives the downlink signal after the UL / DL configuration is changed. The difference from the rate of failure to receive is calculated as the amount of change. Thereby, eNB20 can detect accurately the fall of the reception quality of 2nd UE30 by having changed UL / DL structure.

Also, the offset calculation unit 220 transmits an instruction to lower the transmission power by the first power to the first UE 30 when the amount of change in reception quality is equal to or greater than the first threshold. Moreover, the offset calculation part 220 transmits the instruction | indication which raises transmission power to 2nd electric power to 1st UE30, when the variation | change_quantity of reception quality is less than 2nd threshold value lower than 1st threshold value. . Thereby, eNB20 can suppress the fall of the reception quality of 2nd UE30 by having changed UL / DL structure, and also has the throughput of the uplink data of 1st UE30 by which UL / DL structure was changed. Can be increased.

Also, the offset calculation unit 220 calculates the initial value of the transmission power P of the first UE 30 in the first subframe based on the area of the cell 11 of the eNB 20 and the number of UEs 30 in the cell 11. Thereby, it is possible to prevent the initial value of the transmission power P of the first UE 30 in the first subframe from becoming too large.

In addition, when the transmission power P of the first UE 30 is controlled by the offset calculation unit 220 and the transmission power P of the first UE 30 is equal to or lower than the third power value, the radio channel control unit 222 is UL. / DL configuration is changed back to the previous UL / DL configuration. Thereby, it is possible to prevent the first UE 30 whose UL / DL configuration has been changed from continuing the transmission of the uplink signal with the transmission power P that is too low in the first subframe.

Further, when the transmission power of the first UE 30 reaches the reference transmission power as a result of controlling the transmission power of the first UE 30, the offset calculation unit 220 determines the first UE 30 based on the amount of change in reception quality. The transmission power control is terminated. Thereby, the processing load of eNB20 can be reduced.

In addition, when the offset calculation unit 220 has not instructed the first UE 30 for new transmission power for a predetermined time or more after instructing the transmission power to the first UE 30, the first calculation based on the amount of change in reception quality The control of the transmission power of the UE 30 is finished. Thereby, increase of the processing load of eNB20 can be suppressed.

<Hardware>
FIG. 11 is a diagram illustrating an example of hardware of the communication device 200 that implements the eNB 20. For example, as illustrated in FIG. 11, the communication device 200 includes a network interface circuit 201, a memory 202, a processor 203, a wireless circuit 204, and an antenna 205.

The radio circuit 204 performs predetermined processing such as modulation on the signal output from the processor 203, and transmits the processed signal via the antenna 205. In addition, the radio circuit 204 performs predetermined processing such as demodulation on the signal received via the antenna 205 and outputs the result to the processor 203. The radio circuit 204 implements the functions of, for example, the radio reception unit 214 of the reception unit 21 and the radio transmission unit 236 of the transmission unit 23. The network interface circuit 201 is an interface for connecting to the core network or another eNB 20 by wired connection.

The memory 202 stores programs for realizing the functions of the quality information extraction unit 210, the control information extraction unit 211, the demodulation / decoding unit 212, and the self-interference removal unit 213 of the reception unit 21. The memory 202 also stores programs for realizing the functions of the offset calculation unit 220, the system information management unit 221, and the wireless line control unit 222 of the control unit 22. Further, the memory 202 has functions of a control signal creation unit 230, a pilot creation unit 231, a radio channel control information creation unit 232, an encoding / modulation unit 233, a multiple access processing unit 234, and a delay unit 235 of the transmission unit 23. A program to be realized is stored.

The processor 203 reads out the program stored in the memory 202 from the memory 202 and executes it, whereby the quality information extraction unit 210, the control information extraction unit 211, the demodulation / decoding unit 212, and the self-interference removal unit 213 of the reception unit 21. Realize the function. Further, the processor 203 reads out the program stored in the memory 202 from the memory 202 and executes the program, thereby realizing the functions of the offset calculation unit 220, the system information management unit 221 and the wireless line control unit 222 of the control unit 22. . Further, the processor 203 reads out the program stored in the memory 202 from the memory 202 and executes it, thereby performing the functions of the control signal creation unit 230, the pilot creation unit 231 and the radio channel control information creation unit 232 of the transmission unit 23. Realize. Further, the processor 203 reads out the program stored in the memory 202 from the memory 202 and executes it, thereby realizing the functions of the encoding / modulation unit 233, the multiple access processing unit 234, and the delay unit 235 of the transmission unit 23. .

FIG. 12 is a diagram illustrating an example of hardware of the communication device 300 that implements the UE 30. The communication apparatus 300 includes an antenna 301, a radio circuit 302, a memory 303, and a processor 304, for example, as shown in FIG.

The radio circuit 302 performs predetermined processing such as modulation on the signal output from the processor 304, and transmits the processed signal via the antenna 301. The radio circuit 302 performs predetermined processing such as demodulation on the signal received via the antenna 301 and outputs the result to the processor 304. The radio circuit 302 realizes the functions of, for example, the radio reception unit 310 of the reception unit 31 and the radio transmission unit 330 of the transmission unit 33.

The memory 303 stores programs for realizing the functions of the demodulation / decoding unit 311, the system information extraction unit 312, the control signal extraction unit 313, the pilot extraction unit 314, and the line quality measurement unit 315 of the reception unit 31. . The memory 303 stores a program for realizing the functions of the terminal information control unit 320, the system information management unit 321 and the wireless line control unit 322 of the control unit 32. Further, the memory 303 stores programs for realizing the functions of the encoding / modulation unit 331, the pilot creation unit 332, the control signal creation unit 333, and the radio channel control information creation unit 334 of the transmission unit 33.

The processor 304 reads out the program stored in the memory 303 from the memory 303 and executes it, thereby realizing the functions of the demodulation / decoding unit 311, the system information extraction unit 312, and the control signal extraction unit 313 of the reception unit 31. Further, the processor 304 reads out the program stored in the memory 303 from the memory 303 and executes it, thereby realizing the functions of the pilot extraction unit 314 and the channel quality measurement unit 315. Further, the processor 304 reads out the program stored in the memory 303 from the memory 303 and executes it, thereby realizing the functions of the terminal information control unit 320, the system information management unit 321 and the wireless line control unit 322 of the control unit 32. To do. In addition, the processor 304 reads out the program stored in the memory 303 from the memory 303 and executes the program, whereby the encoding / modulation unit 331, the pilot creation unit 332, the control signal creation unit 333, and the radio channel control of the transmission unit 33 The function of the information creation unit 334 is realized.

<Others>
The disclosed technology is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist.

For example, the eNB 20 of the above embodiment changes the offset A by the change amount ΔA ₁ when the change amount ΔR of the NACK occurrence rate of the second UE 30 after the change of the UL / DL configuration is equal to or greater than the first threshold R _th1. By increasing, the transmission power P of the first UE 30 is decreased by the change amount ΔA ₁ . However, the disclosed technology is not limited to this. For example, when the change amount ΔR of the NACK occurrence rate of the second UE 30 after changing the UL / DL configuration is equal to or greater than the first threshold value R _th1 , the eNB 20 and the first threshold value R _th1 May be instructed to the first UE 30 as the change amount ΔA ₁ of the offset A. For example, when the difference between the change amount ΔR and the first threshold value R _th1 is large, a large change amount ΔA ₁ is instructed to the first UE 30, and the difference between the change amount ΔR and the first threshold value R _th1 Is small, a small change amount ΔA ₁ is instructed to the first UE 30. Thereby, when the NACK incidence rate of the second UE 30 after the UL / DL configuration is changed significantly deteriorates, the eNB 20 can recover the reception quality of the second UE 30 more quickly.

In addition, while controlling the offset A of the transmission power P of the first subframe for the first UE 30 in the cell 11, the eNB 20 of the above embodiment performs UL / DL for the other UE 30 in the cell 11. Do not make configuration changes. Further, as another example, while the eNB 20 controls the offset A of the transmission power P of the first UE 30 in the cell 11, the other cell 11 adjacent to the cell 11 also has another cell 11. You may make it not change a UL / DL structure with respect to UE30 inside. When another cell 11 adjacent to the cell 11 is managed by another eNB 20, the eNB 20 may instruct the other eNB 20 not to change the UL / DL configuration for a predetermined period. Thereby, eNB20 can exclude the influence of having changed UL / DL structure in the adjacent cell 11 in the change of the NACK incidence rate of 2nd UE30 after changing UL / DL structure. .

10 wireless communication system 20 eNB
21 reception unit 210 quality information extraction unit 211 control information extraction unit 212 demodulation / decoding unit 213 self-interference removal unit 214 radio reception unit 22 control unit 220 offset calculation unit 221 system information management unit 222 radio channel control unit 23 transmission unit 230 control signal Creation unit 231 Pilot creation unit 232 Radio channel control information creation unit 233 Encoding / modulation unit 234 Multiple access processing unit 235 Delay unit 236 Radio transmission unit 24 Antenna

Claims (15)

1. In a base station that performs radio communication by switching between an uplink section for receiving an uplink signal and a downlink section for transmitting a downlink signal in time division with each terminal,
   For any one of the terminals, when the switching pattern for switching the uplink section and the downlink section in a time division manner is changed for each subframe, it is set to the downlink section in the switching pattern before the change, and after the change A specifying unit that specifies a first subframe that is a subframe to be changed to an uplink section in the switching pattern;
   An instruction unit for instructing an initial value of transmission power in the first subframe to a first terminal which is a terminal whose switching pattern has been changed;
   For a second terminal that is a terminal other than the first terminal, the downlink signal reception quality in the first subframe before the change of the switching pattern and the first subframe after the change of the switching pattern A calculation unit that calculates a change amount between reception quality of downlink signals in
   The instruction unit includes:
   After the first terminal transmits at the initial transmission power in the first subframe, the transmission power instructed to the first terminal is controlled based on the amount of change. Base station.
2. The calculation unit includes:
   A rate at which the second terminal fails to receive a downlink signal before the switching pattern is changed, and a rate at which the second terminal fails to receive a downlink signal after the change of the switching pattern. The base station according to claim 1, wherein a difference is calculated as the amount of change.
3. The instruction unit includes:
   When the amount of change is equal to or greater than a first threshold, an instruction to reduce transmission power by the first power is transmitted to the first terminal, and the second threshold is lower than the first threshold. 2. The base station according to claim 1, wherein an instruction to increase the transmission power by a second power is transmitted to the first terminal when the power is less than the first terminal.
4. The instruction unit includes:
   The base station according to claim 1, wherein the initial value is calculated based on a cell area of the base station and the number of the terminals in the cell.
5. The controller is
   When the transmission power of the first terminal is controlled by the instruction unit and the transmission power of the first terminal is equal to or lower than a third power value lower than the initial value, the switching pattern is changed. The base station according to claim 1, wherein the previous switching pattern is restored.
6. The instruction unit includes:
   As a result of controlling the transmission power of the first terminal, the transmission power of the first terminal is changed between the physical resources allocated to the first terminal and the base station and the first terminal. 2. The base station according to claim 1, wherein when the reference transmission power determined based on the propagation loss of the first terminal is reached, the control of the transmission power of the first terminal based on the amount of change is terminated.
7. The instruction unit includes:
   If a new transmission power is not instructed to the first terminal for a predetermined time or more after instructing the transmission power to the first terminal, the transmission power of the first terminal is controlled based on the amount of change. The base station according to claim 1, wherein the base station is terminated.
8. Between each terminal, a base station that performs radio communication by switching time-division between an uplink section that receives an uplink signal and a downlink section that transmits a downlink signal,
   For any one of the terminals, when the switching pattern for switching the uplink section and the downlink section in a time division manner is changed for each subframe, it is set to the downlink section in the switching pattern before the change, and after the change Identify a first subframe that is a subframe to be changed to an uplink in the switching pattern;
   Instructing an initial value of transmission power in the first subframe to a first terminal that is a terminal whose switching pattern has been changed,
   For a second terminal that is a terminal other than the first terminal, the downlink signal reception quality in the first subframe before the change of the switching pattern and the first subframe after the change of the switching pattern Calculate the amount of change between the received signal quality of the downlink signal at
   After the first terminal performs transmission with the initial transmission power in the first subframe, a process of controlling transmission power instructing the first terminal based on the amount of change is executed. A control method for a base station.
9. A radio communication system comprising a plurality of terminals and a base station that performs radio communication by switching between an uplink section for receiving an uplink signal and a downlink section for transmitting a downlink signal in a time division manner between each of the plurality of terminals. In
   The base station
   For any one of the terminals, when the switching pattern for switching the uplink section and the downlink section in a time division manner is changed for each subframe, it is set to the downlink section in the switching pattern before the change, and after the change A specifying unit that specifies a first subframe that is a subframe to be changed to an uplink section in the switching pattern;
   An instruction unit for instructing an initial value of transmission power in the first subframe to a first terminal which is a terminal whose switching pattern has been changed;
   For a second terminal that is a terminal other than the first terminal, the downlink signal reception quality in the first subframe before the change of the switching pattern and the first subframe after the change of the switching pattern A calculation unit that calculates a change amount between reception quality of downlink signals in
   The instruction unit includes:
   After the first terminal transmits at the initial transmission power in the first subframe, the transmission power instructed to the first terminal is controlled based on the amount of change. Wireless communication system.
10. In a radio communication system comprising a plurality of terminals and a base station that performs radio communication by switching between an uplink section for receiving an uplink signal and a downlink section for transmitting a downlink signal in a time division manner between each of the plurality of terminals. ,
    For any one of the terminals, when the arrangement pattern of the uplink section and the downlink section in the time domain of a certain length is changed, it is transmitted in a specific uplink section subframe in the changed arrangement pattern Radio communication characterized in that an offset is set between transmission power applied to a signal and transmission power applied to a signal transmitted in an uplink subframe other than the specific uplink subframe. system.
11. 11. The radio communication according to claim 10, wherein the subframe set in the downlink section in the array pattern before the change and the subframe set in the uplink section in the array pattern after the change is the specific uplink section subframe. system.
12. The offset value is notified to the terminal when the arrangement pattern is changed, and after a predetermined time has elapsed, the offset value is invalid or the offset value becomes zero in the terminal. Item 11. The wireless communication system according to Item 10.
13. The wireless communication system according to claim 12, wherein when the arrangement pattern is changed, the value of the predetermined time is notified to the terminal.
14. The radio communication system according to claim 10, wherein the offset value is included in a control signal used by the base station to give permission for signal transmission to the terminal.
15. The radio communication system according to claim 10, wherein the specific uplink subframe is indicated using a code string having the same length as the number of subframes included in one arrangement pattern.

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