JP5198993B2 - Wireless communication method and wireless base station - Google Patents

Description

  The present invention relates to a wireless communication method for a wireless base station that is wirelessly connected to a plurality of wireless communication terminals, and the wireless base station.

Conventionally, a wireless communication system including a wireless base station and a wireless communication terminal is known. In this wireless communication system, in order to maintain communication quality, control is performed to increase or decrease the transmission power when transmitting a wireless signal. In such a conventional wireless communication system, transmission power control by the wireless base station when a wireless signal is transmitted from the wireless communication terminal to the wireless base station (uplink) will be described.
FIG. 6 is an explanatory view schematically showing a conventional wireless communication method. As shown in FIG. 6, the radio communication terminals T1 to T3 are in radio communication with a radio base station BS (Base Station), and a radio communication network is formed by the radio base station BS and the radio communication terminals T1 to T3. Yes.

  FIG. 7 is a flowchart showing a flow of power control processing in a conventional wireless communication method. As shown in FIG. 7, when the radio base station receives a radio signal from the radio communication terminal by starting the operation of the power control process (step S1), the radio base station sets the quality Q of the radio signal every predetermined time. Calculate (step S2). Next, the radio base station detects a change in signal quality over time based on the calculation result. That is, the quality Q (t) of the radio signal at time t is compared with the quality Q (t-1) of the radio signal at time t-1, and the quality Q (t) is improved compared to the quality Q (t-1). It is determined whether or not (step S3).

  If the quality Q (t) is improved as a result of the determination (Yes), the wireless base station requests the wireless communication terminal to reduce the transmission power (step S4), while the quality Q (t) is improved. If not (No), that is, if the quality Q is lower than the quality Q (t−1), the wireless base station requests the wireless communication terminal to increase the transmission power (step S5).

  By the way, when such control is performed to increase or decrease the transmission power when transmitting a radio signal, for example, when the radio communication terminal 1 transmits a radio signal in the radio communication system as shown in FIG. As a result of increasing the transmission power, the wireless communication terminal 2 to which the adjacent communication channel is assigned may cause interference due to the increase of the transmission power in the wireless communication terminal 1, thereby degrading the communication quality. In this case, the radio base station BS requests the radio communication terminal 2 to increase the transmission power in order to maintain the quality of the received radio signal, and the radio communication terminal 2 increases the transmission power. The increase in transmission power in the communication terminal 2 causes the wireless communication terminal 1 to be interfered, and the communication quality is deteriorated.

  FIG. 8 is an explanatory diagram showing a change in power over time with respect to a frequency transmitted by a conventional wireless communication terminal. As shown in FIG. 8, the power with respect to the frequency transmitted by the wireless communication terminals T1 to T3 changes with the interference wave caused by the interference as time elapses from time t−1 to time t. In the figure, the solid line indicates the desired wave at time t, that is, the power at the time of output from the wireless communication terminal, the broken line indicates the desired wave at time t-1, and the stippled portion indicates the disturbing wave at time t. The hatched portion indicates the interference wave at time t-1.

As described above, in the power control (see FIG. 7) in the conventional wireless communication method, the communication quality is deteriorated due to the mutual interference of the radio signals transmitted from the respective wireless communication terminals. If it continues, the radio base station will have to increase the transmission power of the radio communication terminal frequently.
Therefore, to reduce the mutual interference of radio signals, the interference between the radio signal to be transmitted and other radio signals is suppressed by reducing the transmission power when transmitting the radio signal. For example, “transmission power control” "Method" (see Patent Document 1) has been proposed.

In the conventional “transmission power control method”, when a wireless communication device (wireless base station or wireless communication terminal) and other wireless communication devices existing in the vicinity transmit wireless signals at the same timing, interference occurs. Therefore, communication quality is improved by reducing the transmission power to a transmission rate corresponding to the communication quality.
JP 2003-298510 A

In the conventional “transmission power control method” (see Patent Document 1), as one of the wireless communication apparatuses reduces the transmission power, the influence of interference is reduced in the other wireless communication apparatuses, and the communication quality is improved. Is done. However, in this case, in order to increase the transmission rate again, the situation in which the transmission power increases and interference increases again continues.
Further, for example, when the base station controls the transmission power for transmitting the radio signal of the radio communication terminal, a plurality of radio communication terminals with which the radio signal being transmitted interferes with the same base station. Since it is not known whether communication is being performed or wireless communication with another wireless base station is being performed, appropriate processing for reducing interference cannot be performed.

  The object of the present invention is not to continue the situation where interference increases again even if the communication quality is improved, and to grasp the radio communication status of a plurality of radio communication terminals with which radio signals interfere. Another object of the present invention is to provide a radio communication method and a radio base station that can perform appropriate processing for reducing interference.

In order to achieve the above object, a wireless communication method according to the present invention is a wireless communication method in a wireless base station that is wirelessly connected to a plurality of wireless communication terminals, and performs wireless transmission power control after being connected to the wireless base station. shows a transmission step of transmitting an instruction to increase the transmission power to the communication terminal, the signal quality of the radio signal which the wireless base station has received from the radio communication terminal in connection with the radio base station after transmitting the instruction An acquisition step of acquiring a value, a detection step of detecting a wireless communication terminal having a decreased value indicating the signal quality based on the acquired value indicating the signal quality, and a wireless communication terminal having a decreased value indicating the signal quality when it is detected, the radio base station, varying than the modulation class when transmitting the instruction while decreasing the transmission power to the wireless communication terminal transmitting the indication It is characterized by a control step of lowering the class.

The wireless communication method according to the present invention is a wireless communication method in a wireless base station that is wirelessly connected to a plurality of wireless communication terminals, for a wireless communication terminal that performs transmission power control after connecting to the wireless base station . A transmission step of transmitting an instruction to increase transmission power, and obtaining a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction A detection step of detecting a wireless communication terminal whose value indicating the signal quality has decreased based on the acquired value indicating the signal quality, and a communication status in a communication channel assigned to the detected wireless communication terminal Te, the radio base station, an estimation step of estimating the interference between the wireless communication terminal transmitting the indication the detected wireless communication terminal, the estimated scan When we can estimate interference in-up, the control step the radio base station, of lowering the modulation class than the modulation class when transmitting the instruction while decreasing the transmission power to the wireless communication terminal transmitting the indication It is characterized by having.

The radio base station according to the invention is a radio base station that connects a plurality of radio communication terminals and the radio, increasing the transmission power to the wireless communication terminal that performs transmission power control after connecting to the radio base station An instruction unit that transmits an instruction to perform acquisition, an acquisition unit that acquires a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction, and an acquisition A detection unit that detects a wireless communication terminal having a decreased value indicating the signal quality based on a value indicating the signal quality, and the wireless base station when a wireless communication terminal having a decreased value indicating the signal quality is detected. The station includes a control unit that reduces transmission power to the wireless communication terminal that has transmitted the instruction and lowers the modulation class from the modulation class at the time of transmitting the instruction .

The radio base station according to the invention is a radio base station that connects a plurality of radio communication terminals and the radio, increasing the transmission power to the wireless communication terminal that performs transmission power control after connecting to the radio base station An instruction unit that transmits an instruction to perform acquisition, an acquisition unit that acquires a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction, and an acquisition Based on a value indicating the signal quality, a detection unit that detects a wireless communication terminal whose value indicating the signal quality has decreased, and based on a communication status in a communication channel assigned to the detected wireless communication terminal, the wireless If the base station, which can be estimated and the estimation unit for estimating the interference in the estimation unit interference transmitted with wireless communication terminal and the detected wireless communication terminal the instruction, the radio base station It is characterized in that a control unit for lowering the modulation class than the modulation class when transmitting the instruction while decreasing the transmission power to the wireless communication terminal transmitting the indication.

According to the present invention, the radio base station allocates a radio communication channel as a result of instructing a radio communication terminal with poor signal quality to increase transmission power after grasping the current radio communication channel assignment status. When the signal quality of other wireless communication terminals begins to decrease, by reducing the transmission power to the wireless communication terminal that transmitted the instruction and lowering the modulation class than the modulation class when the instruction is transmitted , Since interference with other wireless communication terminals can be suppressed, communication quality in the entire wireless communication system can be stabilized.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a radio base station according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the radio communication terminal according to the embodiment of the present invention.

  As shown in FIG. 1, a radio base station (base station) 10 includes a transmission / reception changeover switch (SW) unit 11 to which an antenna 11a is connected, a radio transmission unit 12, a power control unit 13, a data generation unit 14, and a radio reception unit. 15, a quality calculation unit 16, an interference determination unit 17, and a base station communication control unit 18, and the base station communication control unit 18 includes a frequency allocation management unit 19, a spatial division multiple access (SDMA). ) Management unit 20, uplink power control unit 21, signal quality management unit 22, modulation scheme management unit 23, storage unit 24, comparison unit 25, and control unit 26.

  As shown in FIG. 2, a wireless communication terminal (terminal) 27 includes a transmission / reception changeover switch (SW) unit 28, a wireless transmission unit 29, a power control unit 30, a data generation unit 31, and a wireless reception unit 32 to which an antenna 28a is connected. The terminal communication control unit 35 includes a transmission power recording unit 36, a throughput management unit 37, a quality notification management unit 38, a modulation scheme management unit 39, and a storage unit. 40, a comparison unit 41, and a control unit 42.

A base station 10 (see FIG. 1) having the above configuration and a terminal 27 (see FIG. 2) constitute a radio communication system, and the base station 10 and the terminal 27 are wirelessly connected to form a radio communication network.
In the base station 10, a transmission / reception changeover switch (SW) unit 11 connects the antenna 11a and the wireless transmission unit 12 at the time of transmission, and performs switching to connect the antenna 11a and the wireless reception unit 15 at the time of reception. The unit 12 transmits a radio signal (a control instruction signal for increasing or decreasing transmission power, data in a normal application, or the like) to the terminal 27. The power control unit 13 controls transmission power when transmitting a radio signal to the terminal 27 (downlink) based on an instruction from the control unit 26, and the data generation unit 14 generates transmission data to be transmitted to the terminal 27. To do.

  The wireless reception unit 15 performs reception processing of the wireless signal (data) transmitted from the terminal 27, and the quality calculation unit 16 determines a value indicating the signal quality from the wireless signal received by the wireless reception unit 15, that is, Q ( t) is calculated and obtained. Based on the signal quality acquired by the quality calculation unit 16, the interference determination unit 17 determines whether there is interference between terminals due to transmission power control, and outputs the determination information to the base station communication control unit 18. . The base station communication control unit 18 outputs control information for controlling the transmission state of the radio signal transmitted from the base station 10 to the power control unit 13 and the data generation unit 14 based on the determination information input from the interference determination unit 17. .

  In the base station communication control unit 18, the frequency allocation management unit 19 manages the allocation status of communication channels that can be allocated to the terminal 27 by the base station 10, and grasps the status. When the wireless communication system adopts SDMA, the SDMA management unit 20 manages the spatial multiplexing number in each communication channel and the communication channel assignment status to the terminal 27 and grasps the status.

The uplink power control unit 21 controls the transmission power when the terminal 27 transmits a radio signal to the base station 10 using the value indicating the signal quality acquired by the quality calculation unit 16.
The signal quality management unit 22 stores and manages at least a value indicating the signal quality acquired by the base station 10 immediately before, and the modulation scheme management unit 23 performs transmission and reception during communication with the terminal 27 performing wireless communication. The modulation method (modulation class) when modulating and demodulating data to be managed is managed. The storage unit 24 stores the state of transmission power and the state of throughput when each terminal 27 transmits a radio signal to the base station 10.

The comparison unit 25 compares the value indicating the previous signal quality stored in the signal quality management unit 22 with the value indicating the acquired signal quality. The storage unit 24 and the comparison unit 25 function when performing transmission power control.
When the control unit 26 controls the operation of each component in the base station 10 and performs transmission power control of the terminal 27, the control unit 26 controls transmission power when transmitting a radio signal to the terminal 27, The control instruction signal is transmitted.

  In the terminal 27 (see FIG. 2), the transmission / reception changeover switch (SW) unit 28 performs switching for connecting the antenna 28a and the wireless transmission unit 29 at the time of transmission and connecting the antenna 28a and the wireless reception unit 32 at the time of reception, The wireless transmission unit 29 transmits a wireless signal (control instruction signal for increasing or decreasing transmission power, data in a normal application, or the like) to the base station 10. The power control unit 30 controls transmission power when transmitting a radio signal to the base station 10 (uplink) based on an instruction from the control unit 42, and the data generation unit 31 transmits transmission data to be transmitted to the base station 10. Is generated.

The radio reception unit 32 performs reception processing of the radio signal (data) transmitted from the base station 10, and the quality calculation unit 33 calculates a value indicating the signal quality in the downlink from the radio signal received by the radio reception unit 32. Calculate and get.
The terminal communication control unit 35 outputs control information for controlling the transmission state of the wireless communication signal transmitted from the terminal 27 to the power control unit 30 and the data generation unit 31.

  In the terminal communication control unit 35, the transmission power recording unit 36 records the value of the transmission power controlled immediately before, and the throughput management unit 37 determines the throughput value based on the value indicating the signal quality acquired from the base station 10. Remember and manage. The quality notification management unit 38 acquires and manages the value indicating uplink signal quality acquired from the base station 10, that is, Q (t), and the modulation scheme management unit 39 is a base station that performs radio communication. 10 manages a modulation scheme (modulation class) for modulating and demodulating data to be transmitted and received during communication with the network 10. The storage unit 40 stores a state of transmission power and a state of throughput immediately before causing the base station 10 to control transmission power.

  The comparison unit 41 compares the value indicating the previous signal quality managed by the quality notification management unit 38 with the value indicating the acquired signal quality. The control unit 42 controls the operation of each component unit in the terminal 27 and determines whether to increase or decrease the modulation class or increase or decrease the transmission power when transmitting a radio signal.

  In the terminal 27 having the above configuration (see FIG. 2), the reception signal input to the terminal 27 via the antenna 28 a is switched by the transmission / reception changeover switch (SW) 28 and sent to the wireless reception unit 32. In the radio receiver 32, necessary signals are extracted and amplified with respect to the received signals, and demodulated. For the demodulated signal, the quality calculation unit 33 calculates and estimates the quality of the received signal.

In the terminal communication control unit 35, the throughput management unit 37 manages the throughput of the entire wireless communication system based on the detection result.
Also, the terminal 27 reports the calculated signal quality to the base station 10 via the antenna 28a, records the transmission power of the own station in time series in the transmission power recording unit 36, and modulates the modulation scheme in the modulation scheme management unit 39. Manage. The uplink signal from the terminal 27 to the base station 10 is modulated data is generated by the data generation unit 31, the transmission power is controlled by the power control unit 30, and is amplified to a desired frequency and power by the wireless transmission unit 29, Thereafter, the light is emitted to the space via the antenna 28a via the transmission / reception changeover switch unit 28.

  As described above, the base station (wireless base station) 10 wirelessly connected to the plurality of terminals (wireless communication terminals) 27 transmits a command for increasing the transmission power in any one of the plurality of terminals 27. Unit (instruction unit) 26, quality calculation unit (acquisition unit) 16 that acquires a value indicating the signal quality of a radio signal received from a terminal 27 other than terminal 27 that has increased transmission power, and acquired signal quality When the base station communication control unit (detection unit) 18 that detects the terminal 27 whose signal quality value has decreased and the terminal 27 whose signal quality value has decreased are detected based on the value indicating the signal quality, the transmission power And a base station communication control unit (control unit) 18 that reduces the transmission power of the terminal 27 that has increased and lowers the modulation class.

  In addition, the base station 10 has a communication status in a communication channel assigned to the terminal 27 detected by the control unit 26, the quality calculation unit 16, the base station communication control unit 18, and the base station communication control unit 18, for example, Based on the electric field strength of the received radio signal, the interference determination unit (estimation unit) 17 that estimates interference between the terminal 27 that has increased transmission power and the detected terminal 27, and the interference determination unit 17 can estimate interference. A base station communication control unit (control unit) 18 that decreases the transmission power of the terminal 27 that has increased the transmission power and lowers the modulation class.

FIG. 3 is a flowchart showing a flow of control operation for changing the modulation class in the base station 10 shown in FIG. As shown in FIG. 3, when the control operation of the base station 10 is started, the base station 10 first receives a transmission signal from the terminal 27 (step S101), and then receives the signal quality Q ( t) is calculated (step S102), and the frequency usage state is monitored (step S103).
Thereafter, the base station 10 compares the reception quality Q (t) at time t with the reception quality Q (t−1) at time t−1, and receives the reception quality Q (t−1) from the reception quality Q (t). Is better (Q (t) <Q (t-1)), that is, whether the reception quality is not improved is determined (step S104).

  As a result of the determination, the reception quality Q (t−1) is not better than the reception quality Q (t) (No), that is, the reception quality Q (t) is improved compared to the reception quality Q (t−1). If yes, the process returns to step S101. On the other hand, the reception quality Q (t-1) is better than the reception quality Q (t) (Yes), that is, the reception quality Q (t) is not improved compared to the reception quality Q (t-1). If the value indicating the signal quality is reduced, the base station 10 requests the terminal 27 to increase the transmission power (step S105).

  After the terminal 27 increases the transmission power due to a request for an increase in transmission power from the base station 10, the base station 10 causes interference due to the terminal 27 increasing the transmission power. It is determined whether or not the disturbance to the terminal (station) is increased (step S106). That is, the base station 10 transmits a value indicating the signal quality of a radio signal received from another terminal 27 other than the terminal 27 that has increased the transmission power after transmitting an instruction to increase the transmission power in any of the terminals 27. The terminal 27 which acquired and the value which shows the acquired signal quality fell, ie, the terminal 27 which received the disturbance by interference, is detected.

  If the result of determination in step S106 is that interference with other stations due to interference has increased (Yes), the base station 10 decreases the transmission power and lowers the modulation class for the terminal 27 whose transmission power has been increased. A request is made (step S107), and then the process ends. On the other hand, as a result of the determination, if the interference to other stations due to interference has not increased (No), the process is terminated.

  As described above, the wireless communication method in the base station (wireless base station) 10 wirelessly connected to the plurality of terminals (wireless communication terminals) 27 according to the present invention is the transmission power in any one of the plurality of terminals 27. A transmission step of transmitting an instruction to increase the transmission power, an acquisition step of acquiring a value indicating the signal quality of a radio signal received from another terminal 27 other than the terminal 27 that has increased the transmission power, and a value indicating the acquired signal quality And detecting the terminal 27 whose signal quality value has been reduced, and reducing the transmission power of the terminal 27 that has increased the transmission power when the terminal 27 having a low signal quality value is detected. And a control step for lowering the modulation class.

  The wireless communication method in the base station 10 that is wirelessly connected to the plurality of terminals 27 is based on the transmission step, the acquisition step, the detection step, and the communication status in the communication channel assigned to the detected terminal 27. An estimation step for estimating interference between the detected terminal 27 and the detected terminal 27. When interference can be estimated in the estimation step, the transmission power of the terminal 27 having increased transmission power is decreased and modulated. And a control step for lowering the class.

Here, the value indicating the signal quality of a radio signal received from another radio communication terminal is, for example, a signal-to-noise ratio (SNR).
In addition, the modulation class of the wireless communication terminal that has increased the transmission power is decreased because the value indicating the signal quality at the other wireless communication terminal is decreased by increasing the transmission power of any of the wireless communication terminals. This is because it is estimated that interference has occurred and the modulation class of the wireless communication terminal whose transmission power has been increased is lowered so as not to cause interference, thereby improving the signal quality of other wireless communication terminals.

Further, the interference estimated in the estimation step is interference between wireless communication terminals to which a wireless base station has assigned a communication channel,
(1) Interference in adjacent channel: interference between adjacent communication channels in assignable communication channel (2) Channel interference in operation band: any two or more communication not adjacent in assignable communication channel Interference between channels (3) Interference in the same communication channel: interference in the same (spatial) channel in SDMA, or at least used by radio communication terminals connected to other radio base stations and other radio base stations It becomes interference in the channel of the same frequency.

  In (1) and (2), by grasping the level of the radio signal based on the electric field strength received by the communication channel and the level of the desired wave (interference wave) included in the radio signal, interference in the communication channel is prevented. It is possible to ascertain whether or not it has occurred, and further, by performing similar grasps in other communication channels, it is possible to estimate interference between wireless communication terminals using the assigned communication channel.

  In (3), in addition to the desired wave that the user wants to receive in the radio signal received in the communication channel, the radio signal of another radio communication terminal assigned with the same (spatial) channel, another base station, or the other base It is determined whether or not a radio signal transmitted from a radio communication terminal connected to the station is included. Specifically, by looking at bscc (identification information for recognizing that data is transmitted / received when the base station performs wireless communication) included in the control signal in each wireless signal, Or a jamming wave from another base station or a wireless communication terminal connected to another base station. If no interference wave is included, it is determined as interference between wireless communication terminals to which the same channel (spatial channel) assigned by itself is assigned.

Next, in the estimation step in the radio base station, a radio communication terminal in which interference with a radio signal transmitted from another radio base station or a radio communication terminal connected to the other radio base station occurs is estimated. Processing will be described.
It is determined whether or not the radio signal received from the communication channel includes a radio signal transmitted from another base station or the other base station in addition to the desired wave that the user wants to receive. Specifically, by looking at bscc (identification information for recognizing that data is transmitted / received when the base station performs wireless communication) included in the control signal in each wireless signal, Whether it is a wave or a jamming wave. Then, it is determined whether or not there is interference between the wireless communication terminals assigned by the wireless base station itself.

The above-described interference detection is handled as follows.
(1) Interference detection by the same channel-Desired wave determination by bscc-> If it is not applicable bscc, it is determined as a jamming wave from another base station or a wireless communication terminal connected to another base station-Spatial number-> Spatial For example, it is determined that the interference is the same in SDMA. ・ Signal to interference plus noise power ratio (SINR) amount → Determines whether there is interference due to quality control.

(2) Interference detection in adjacent / operating band-Whether channel is allocated in the band managed by own station-> Channel can be specified if connected-DSSI detection of each channel-> Desired wave (3 ) Interference detection with other stations ・ Whether or not the channel is allocated in the band managed by the own station ・ Detects increase or decrease in throughput in the network that accommodates each base station

The modulation class will be described.
The modulation class refers to a combination of a plurality of modulation schemes and channel coding schemes, and a modulation class that determines throughput is selected according to selection conditions.
FIG. 4 is an explanatory diagram showing an example of combinations of channel coding schemes and modulation schemes in each modulation class. As shown in FIG. 4, for example, modulation classes 0 to 5 are defined. In this modulation class, the signal-to-interference noise power ratio (SINR) degradation tolerance is the highest in the modulation class 0 and decreases as the modulation class becomes higher (0 → 5). Conversely, the information amount per symbol is the highest in modulation class 5, the throughput is high, and the information amount per symbol is small and the throughput is low as the modulation class is low (5 → 0).

  FIG. 5 is an explanatory diagram schematically showing a wireless communication state in a base station and a plurality of terminals connected to the base station. As shown in FIG. 5, the radio communication terminals T1 to T3 are in radio communication with the radio base station BS, and the radio base station BS and the radio communication terminals T1 to T3 form a radio communication network. Here, the wireless communication terminal T3 is a terminal that controls transmission power.

  First, the radio communication terminal T3 controls transmission power based on a value indicating the signal quality of the radio communication signal after connecting to the radio base station BS. At this time, in the state as shown in FIG. 5, the radio communication terminal T3 connected to the radio base station BS performs radio communication, so that the other radio communication terminals T1, T2 receive interference, and the radio communication terminal T1, The communication quality of T2 becomes unstable, and further, the communication quality of the entire wireless communication system is also unstable.

  For this reason, the wireless communication terminal T3 estimates that there is a possibility of causing interference to the other wireless communication terminals T1 and T2 by connecting to the wireless base station BS and performing wireless communication. The communication terminal T3 is controlled to reduce the transmission power and lower the modulation class (see FIG. 3). That is, by reducing the transmission power of the wireless communication terminal that has instructed to increase the transmission power and lowering the modulation class, interference with other wireless communication terminals can be suppressed. Since it is possible to cope with a case where the quality deteriorates and a state in which the current modulation class remains as it cannot be demodulated, it is possible to stabilize the communication quality in the entire wireless communication system.

As described above, in the radio communication method according to the present invention, the radio base station BS increases the transmission power in the uplink (uplink line) of the radio communication terminal, so that the interference between the terminals increases, and the radio communication If it is determined that the communication quality of the entire system is degraded (not improved), the communication quality of the entire wireless communication system is improved by reducing the transmission power in the uplink of the wireless communication terminal and lowering the modulation class And stabilize.
Although the present invention has been described with reference to the above-described embodiment, it is not limited to this embodiment. Therefore, what is implemented as a change aspect without deviating from the meaning of the present invention is also included.

It is a block diagram which shows schematic structure of the wireless base station which concerns on one embodiment of this invention. It is a block diagram which shows schematic structure of the radio | wireless communication terminal which concerns on one embodiment of this invention. 3 is a flowchart showing a flow of a control operation for changing a modulation class in the terminal shown in FIG. 2. It is explanatory drawing which shows an example of a modulation class selection condition by a table | surface. It is explanatory drawing which shows typically the radio | wireless communication state in the some terminal connected to the base station and the base station. It is explanatory drawing which showed the conventional radio | wireless communication method typically. It is a flowchart which shows the flow of the power control process in the conventional radio | wireless communication method. It is explanatory drawing which shows the change by the time passage of the electric power with respect to the frequency which the conventional radio | wireless communication terminal is transmitting in a graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio base station 11a, 28a Antenna 11, 28 Transmission / reception switch part 12, 29 Wireless transmission part 13, 30 Power control part 14, 31 Data generation part 15, 32 Radio reception part 16, 33 Quality calculation part 17 Interference determination part 18 Base station communication control unit 19 Frequency allocation management unit 20 Spatial multiple access control unit 21 Up power control unit 22 Signal quality management unit 23, 39 Modulation method management unit 24, 40 Storage unit 25, 41 Comparison unit 26, 42 Control unit 27 Wireless communication terminal 35 terminal communication control unit 36 transmission power recording unit 37 throughput management unit 38 quality notification management unit BS wireless base station T1, T2, T3 wireless communication terminal

Claims (4)

A wireless communication method in a wireless base station wirelessly connected to a plurality of wireless communication terminals,
A transmission step of transmitting an instruction to increase the transmission power to the wireless communication terminal that performs transmission power control after connecting to the radio base station,
An acquisition step of acquiring a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction ;
Based on the acquired value indicating the signal quality, a detection step of detecting a wireless communication terminal whose value indicating the signal quality has decreased,
Modulation when the wireless base station decreases the transmission power and transmits the instruction to the wireless communication terminal that has transmitted the instruction when a wireless communication terminal having a decreased value indicating the signal quality is detected And a control step for lowering the modulation class than the class. A wireless communication method in a wireless base station wirelessly connected to a plurality of wireless communication terminals,
A transmission step of transmitting an instruction to increase the transmission power to the wireless communication terminal that performs transmission power control after connecting to the radio base station,
An acquisition step of acquiring a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction ;
Based on the acquired value indicating the signal quality, a detection step of detecting a wireless communication terminal whose value indicating the signal quality has decreased,
Based on the communication status in the communication channel assigned to the detected wireless communication terminal, the wireless base station estimates the interference between the wireless communication terminal that transmitted the instruction and the detected wireless communication terminal Steps,
Control in which, when interference can be estimated in the estimation step, the radio base station reduces the transmission power to the radio communication terminal that has transmitted the instruction and lowers the modulation class from the modulation class at the time of transmitting the instruction. A wireless communication method comprising the steps of: A wireless base station that is wirelessly connected to a plurality of wireless communication terminals,
An instruction unit that transmits an instruction to increase the transmission power to the wireless communication terminal that performs transmission power control after connecting to the radio base station,
An acquisition unit for acquiring a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction ;
Based on a value indicating the acquired signal quality, a detection unit that detects a wireless communication terminal whose value indicating the signal quality has decreased,
Modulation when the wireless base station decreases the transmission power and transmits the instruction to the wireless communication terminal that has transmitted the instruction when a wireless communication terminal having a decreased value indicating the signal quality is detected And a control unit for lowering the modulation class than the class. A wireless base station that is wirelessly connected to a plurality of wireless communication terminals,
An instruction unit that transmits an instruction to increase the transmission power to the wireless communication terminal that performs transmission power control after connecting to the radio base station,
An acquisition unit for acquiring a value indicating a signal quality of a radio signal received from a radio communication terminal connected to the radio base station after the radio base station transmits the instruction ;
Based on a value indicating the acquired signal quality, a detection unit that detects a wireless communication terminal whose value indicating the signal quality has decreased,
Based on the communication status in the communication channel assigned to the detected wireless communication terminal, the wireless base station estimates the interference between the wireless communication terminal that transmitted the instruction and the detected wireless communication terminal And
Control in which the radio base station reduces transmission power to the radio communication terminal that has transmitted the instruction and lowers the modulation class from the modulation class at the time of transmitting the instruction when interference can be estimated in the estimation unit And a radio base station.

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