JP4570741B2 - Base station apparatus, communication terminal apparatus and communication method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a base station apparatus, a communication terminal apparatus, and a communication method used in a cellular communication system.
[0002]
[Prior art]
In the cellular communication system, one base station performs wireless communication simultaneously with a plurality of communication terminals, and with the recent increase in demand, it is required to increase transmission efficiency.
[0003]
HDR (High Data Rate) has been proposed as a technique for improving the transmission efficiency of a downlink from a base station to a communication terminal. HDR is a method in which a base station performs scheduling for allocating communication resources to each communication terminal and assigns the communication resources to each communication terminal, and further sets a transmission rate for each communication terminal according to communication quality and transmits data.
[0004]
Hereinafter, operations performed by the base station and the communication terminal for setting the transmission rate in the HDR will be described with reference to FIG. In FIG. 3, the base station 11 is currently communicating with the communication terminals 12 to 14.
[0005]
First, the base station 11 transmits a pilot signal to each of the communication terminals 12-14. Each of the communication terminals 12 to 14 estimates the communication quality by CIR (desired wave-to-interference wave ratio) based on the pilot signal and obtains a transmission rate at which communication is possible. And each communication terminal 12-14 selects the communication mode which is a combination of packet length, error correction, and a modulation system based on the transmission rate which can communicate, and transmits the signal which shows communication mode to the base station 11. Note that the types of modulation schemes that can be used in each system are determined in advance, such as BPSK, QPSK, 16QAM, and 64QAM. The types of error correction that can be used in each system are determined in advance, such as 1/2 turbo code, 1/3 turbo code, and 3/4 turbo code. A plurality of transmission rates that can be used in each system are determined by a combination of the packet length, the modulation method, and the error correction method. Each communication terminal selects one of the transmission rates.
[0006]
The base station 11 performs scheduling based on the communication mode selected by each communication terminal 12 to 14, sets a transmission rate for each communication terminal, and sends each communication terminal 12 to 14 to each communication terminal through a control channel. A signal indicating communication resource allocation is broadcast. In general, a base station preferentially allocates communication resources to communication terminals having a high communication rate in consideration of improvement in transmission efficiency of the system.
[0007]
Then, the base station 11 transmits data only to the corresponding communication terminal at the allocated time. For example, when time t1 is allocated to the communication terminal 12, the base station 11 transmits data only to the communication terminal 12 at time t1, and does not transmit to the communication terminals 13 and 14.
[0008]
Thus, conventionally, by setting a transmission rate for each communication terminal according to communication quality using HDR, and preferentially allocating communication resources to communication terminals having a high communication rate, communication efficiency of the entire system can be improved. It is increasing.
[0009]
Here, in general, there is an upper limit on transmission power, and the higher the transmission rate, the stronger the transmission power is required. Therefore, the area radius that can be received with the desired reception quality is smaller as the transmission rate is higher. . Accordingly, communication terminals existing around the cell edge can receive the HDR service only at a low transmission rate.
[0010]
[Problems to be solved by the invention]
However, if the base station transmits data at a low transmission rate, it takes a long time until the transmission is completed. During this time, other communication terminals cannot receive the HDR service, resulting in a decrease in the transmission efficiency of the system. There is a problem.
[0011]
The present invention has been made in view of this point, and an object of the present invention is to provide a base station apparatus, a communication terminal apparatus, and a communication method that can further improve transmission efficiency in HDR.
[0012]
[Means for Solving the Problems]
The base station apparatus of the present invention allocates communication resources based on the first information transmitted from each communication terminal apparatus in communication and indicating the downlink transmission rate at which each communication terminal apparatus can receive with a desired quality. When the number of communication terminal devices that have transmitted the first information is greater than a predetermined threshold, it is determined that the traffic situation has increased and is selected according to whether the traffic situation has increased. A transmission rate determining means for determining a possible transmission rate; a control information transmitting means for creating second information indicating communication resource allocation and third information indicating a selectable transmission rate; accordance allocation resource adopts a configuration comprising a data transmission means for transmitting data to a specific communication terminal apparatus.
[0013]
The base station apparatus of the present invention employs a configuration in which the transmission rate determining means excludes a low transmission rate from the options when the traffic situation is increasing.
[0015]
The base station apparatus of the present invention, the transmission rate determination means adopts a sequential alters constituting said threshold according to the distribution of the requested transmission rate.
[0016]
The base station apparatus of the present invention allocates communication resources based on the first information transmitted from each communication terminal apparatus in communication and indicating the downlink transmission rate at which each communication terminal apparatus can receive with a desired quality. If the allocation means to perform and the number of communication terminal devices that have requested a transmission rate lower than the first threshold value are greater than the second threshold value, it is determined that the traffic situation has increased, and whether or not the traffic situation has increased. Transmission rate determining means for determining a selectable transmission rate according to the control information, and control information transmitting means for generating second information indicating the allocation of communication resources and third information indicating the selectable transmission rate and transmitting them to the communication terminal apparatus And data transmission means for transmitting data to a specific communication terminal device in accordance with communication resource allocation .
[0017]
The base station apparatus of the present invention employs a configuration in which the transmission rate determining means sequentially changes at least one of the first threshold value and the second threshold value according to the distribution of the requested transmission rate.
[0018]
With these configurations, when the traffic situation is increasing, the base station apparatus can exclude a low transmission rate from the options, so that data is not transmitted to the communication terminal apparatus at a low transmission rate. The transmission efficiency can be improved.
[0019]
The base station apparatus of the present invention employs a configuration in which the transmission rate determining means detects the traffic information of neighboring cells and excludes the low transmission rate from the options only when there is a margin in the capacity of the neighboring cells.
[0020]
With this configuration, if the base station apparatus cooperates with the base station apparatus of another cell, a dynamic service area can be constructed, and a communication terminal apparatus that cannot receive a service at the selected transmission rate is connected to the other cell. Can receive service.
[0021]
In the base station apparatus of the present invention, the transmission rate determining means detects traffic information of another communication system that provides a service in a neighboring area, and sets a low transmission rate only when there is a margin in the capacity of the other communication system. Use a configuration that excludes the option.
[0022]
With this configuration, a communication terminal that cannot receive a service at a selected transmission rate can search for another system that can receive the service, can be handed over if necessary, and can receive a transfer service in the other system.
[0023]
The communication terminal apparatus of the present invention calculates a reception rate of a signal transmitted from the base station apparatus described in any of the above, and a transmission rate that can be received with a desired quality based on the measured reception quality The transmission rate calculating means for performing the demodulation, the demodulating means for demodulating the second information and the third information from the signal transmitted from the base station apparatus, and the calculated transmission rate can be selected based on the third information Control information transmitting means for creating only first information and transmitting it to the base station apparatus, and data receiving means for receiving data transmitted from the base station apparatus according to the second information Communication terminal device.
[0024]
With this configuration, the communication terminal apparatus does not transmit a signal for requesting data transmission when the service cannot be received at the selected transmission rate, such as being present in the vicinity of the cell edge, and thus power consumption can be reduced. .
[0025]
The communication method of the present invention is a communication method used in a base station apparatus, and indicates a downlink transmission rate transmitted from each communication terminal apparatus in communication and capable of being received at a desired quality by each of the communication terminal apparatuses. An allocation step of allocating communication resources based on the first information, and determining that the traffic situation is increasing when the number of communication terminal devices that have transmitted the first information is greater than a predetermined threshold; A communication rate determining step of determining a transmission rate that can be selected according to whether or not the communication rate increases, second information indicating allocation of communication resources, and third information indicating a selectable transmission rate. A control information transmission step for transmitting data to the communication terminal device and a data transmission step for transmitting data to a specific communication terminal device in accordance with the allocation of communication resources . The communication method of the present invention is a communication method used in a base station apparatus, and is transmitted from each communication terminal apparatus in communication and can be received at a desired quality by each communication terminal apparatus. If the number of communication terminal devices that request a transmission rate lower than the first threshold is greater than the second threshold, the traffic situation is increased. A transmission rate determining step for determining and determining a transmission rate that can be selected according to whether or not the traffic situation is increasing; second information indicating communication resource allocation; and third information indicating a selectable transmission rate A control information transmission step of creating and transmitting to the communication terminal device; and a data transmission step of transmitting data to a specific communication terminal device according to the allocation of communication resources. Take a way.
[0026]
With this method, the base station apparatus does not transmit data to the communication terminal apparatus at a low transmission rate, and the transmission efficiency of the system can be improved.
[0027]
In addition, when the communication terminal apparatus cannot receive a service at the selected transmission rate, such as being in the vicinity of the cell edge, it does not transmit a signal for requesting data transmission, so that power consumption can be reduced.
[0028]
In addition, since a communication terminal device that cannot receive a service at the selected transmission rate can search whether or not the service can be received in another cell, if the base station device cooperates with a base station device in another cell, A dynamic service area can be constructed.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
The essence of the present invention is that the base station determines the traffic status and prevents the communication terminal from selecting a low transmission rate when the traffic is increasing.
[0030]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a configuration of a base station according to an embodiment of the present invention.
[0031]
In FIG. 1, a transmission rate determination unit 101 determines a traffic rate based on a data rate control (hereinafter referred to as “DRC”) signal output from a demodulation unit 115 described later and determines a selectable transmission rate.
[0032]
For example, if the number of communication terminal devices that have transmitted DRC signals is greater than a threshold value, or if the number of communication terminal devices that have requested a low transmission rate is greater than the threshold value, the transmission rate determination unit 101 increases the traffic situation. The low transmission rate is excluded from the options. In this case, the transmission rate determination unit 101 can also sequentially change the threshold according to the distribution of the requested transmission rate.
[0033]
Alternatively, the transmission rate determining unit 101 detects traffic information of neighboring cells or traffic information of other communication systems providing services in the neighboring area, and transmission is low only when there is a margin in the capacity of neighboring cells or other communication systems. Remove rate from choice.
[0034]
Then, the transmission rate determining unit 101 outputs information indicating the determined selectable transmission rate to the control signal generating unit 106. The DRC signal is a signal indicating a transmission rate at which the communication terminal can receive with a desired quality.
[0035]
The allocating unit 102 grasps the transmission rate at which each communication terminal can communicate based on the DRC signal output from the demodulating unit 115 described later, and determines the allocation of communication resources to each communication terminal. Allocation unit 102 then instructs buffer 103 to output downlink transmission data based on the determined allocation of communication resources, instructs adaptive modulation unit 104 to specify a modulation scheme for downlink transmission data, and adaptive spreading unit 105. To the spreading code to be multiplied with the downlink transmission data. Also, the allocation unit 102 outputs information indicating the determined allocation of communication resources to the control signal creation unit 106.
[0036]
Buffer 103 holds downlink transmission data, and outputs downlink transmission data for a predetermined communication terminal to adaptive modulation section 104 in accordance with an instruction from allocation section 102. Adaptive modulation section 104 modulates the output signal of buffer 103 in accordance with an instruction from allocation section 102 and outputs the modulated signal to adaptive spreading section 105. Adaptive spreading section 105 spreads the output signal of adaptive modulation section 104 in accordance with the instruction from allocation section 102 and outputs the result to multiplexing section 109.
[0037]
The control signal creation unit 106 creates a control signal including information indicating selectable transmission rates and information indicating communication resource allocation, and outputs the control signal to the modulation unit 107.
[0038]
Modulation section 107 modulates the control signal and pilot signal, and outputs the result to spreading section 108. At the start of communication, only the pilot signal is modulated by modulation section 107. Spreading section 108 spreads the output signal of modulating section 107 and outputs the result to multiplexing section 109.
[0039]
Multiplexing section 109 time-multiplexes the spread control signal and pilot signal at a predetermined interval on the spread downlink transmission data, and outputs the result to transmission RF section 110. The transmission RF unit 110 converts the frequency of the output signal of the multiplexing unit 109 into a radio frequency and outputs it to the duplexer 111.
[0040]
The duplexer 111 wirelessly transmits the output signal of the transmission RF unit 110 from the antenna 112 to the communication terminal. The duplexer 111 outputs a signal wirelessly transmitted from each communication terminal and wirelessly received by the antenna 112 to the reception RF unit 113.
[0041]
The reception RF unit 113 converts the frequency of the radio frequency signal output from the duplexer 111 into baseband and outputs the baseband to the despreading unit 114. Despreading section 114 despreads the baseband signal and outputs it to demodulation section 115.
[0042]
Demodulation section 115 demodulates the output signal of despreading section 114 to extract a DRC signal, and outputs the DRC signal to transmission rate determination section 101 and allocation section 102.
[0043]
FIG. 2 is a block diagram showing a configuration of the communication terminal according to the present embodiment.
[0044]
In FIG. 2, a transmission rate calculation unit 201 calculates a transmission rate that can be received with a desired quality based on CIR measured by a CIR measurement unit 212 described later, and outputs the transmission rate to the DRC signal creation unit 202.
[0045]
The DRC signal generator 202 uses only information indicating the selectable transmission rates demodulated by the demodulator 213, which will be described later, as a determination criterion, and only when the transmission rate calculated by the transmission rate calculator 201 can be selected. A DRC signal is created and output to the modulation unit 203. Further, the DRC signal creation unit 202 instructs the adaptive despreading unit 209 on a spreading code to multiply the downlink reception data based on information indicating communication resource allocation demodulated by the demodulating unit 213 described later, Instructs adaptive demodulation section 210 on the demodulation method of downlink received data.
[0046]
Modulating section 203 modulates the DRC signal and outputs it to spreading section 204. Spreading section 204 spreads the output signal of modulation section 203 and outputs the result to transmission RF section 205. The transmission RF unit 205 converts the output signal of the spreading unit 204 to a radio frequency and outputs it to the duplexer 206.
[0047]
The duplexer 206 wirelessly transmits the output signal of the transmission RF unit 205 from the antenna 207 to the base station. The duplexer 206 outputs a signal wirelessly transmitted from the base station and wirelessly received by the antenna 207 to the reception RF unit 208.
[0048]
The reception RF unit 208 converts the frequency of the radio frequency signal output from the duplexer 206 into baseband, and outputs the baseband to the adaptive despreading unit 209 and the despreading unit 211.
[0049]
Adaptive despreading section 209 despreads the data component of the baseband signal and outputs it to adaptive demodulation section 210 in accordance with the instruction from DRC signal creation section 202. Adaptive demodulation section 210 demodulates the output signal of adaptive despreading section 209 and extracts received data in accordance with instructions from DRC signal creation section 202.
[0050]
The despreading unit 211 despreads the control signal component of the baseband signal and outputs it to the CIR measurement unit 212 and the demodulation unit 213. The CIR measurement unit 212 measures the CIR from the pilot signal component output from the despreading unit 211 and outputs it to the DRC signal creation unit 202. Demodulation section 213 demodulates the output signal of despreading section 211 and outputs information indicating a selectable transmission rate and information indicating allocation of communication resources to DRC signal creation section 202.
[0051]
Next, a signal transmission / reception procedure between the base station shown in FIG. 1 and the communication terminal shown in FIG. 2 will be described.
[0052]
First, at the start of communication, a pilot signal is modulated by modulation section 107 of the base station, spread by spreading section 108, and output to multiplexing section 109. Only the spread pilot signal is output from the multiplexing section 109 to the transmission RF section 110. The spread pilot signal is frequency-converted to a radio frequency by transmission RF section 110 and is radio-transmitted from antenna 112 to each communication terminal via duplexer 111.
[0053]
A radio signal including only a pilot signal component wirelessly transmitted from the base station is received by the antenna 207 of the communication terminal, and frequency-converted to baseband by the reception RF unit 208 via the duplexer 206. The pilot signal component of the baseband signal is despread by despreading section 211 and output to CIR measurement section 212.
[0054]
Next, CIR measurement section 212 calculates CIR based on the pilot signal output from despreading section 211, and transmission rate calculation section 201 calculates a transmission rate that can be received with a desired quality based on CIR. The Then, the DRC signal creation unit 202 creates a DRC signal indicating the transmission rate.
[0055]
The DRC signal is modulated by the modulation unit 203, spread by the spreading unit 204, frequency-converted to a radio frequency by the transmission RF unit 205, and wirelessly transmitted from the antenna 207 to the base station via the duplexer 206.
[0056]
A signal wirelessly transmitted from the communication terminal is received by the antenna 112 of the base station and input to the reception RF unit 113 via the duplexer 111. The signal input to the reception RF unit 113 is frequency-converted to baseband, despread by the despreading unit 114, demodulated by the demodulation unit 115, and a DRC signal is extracted.
[0057]
Next, the transmission rate determination unit 101 determines the traffic status based on the DRC signal and determines a selectable transmission rate. At the same time, the allocation unit 102 determines allocation of communication resources to each communication terminal based on the DRC signal.
[0058]
Then, the control signal creation unit 106 creates a control signal including information indicating selectable transmission rates and information indicating communication resource allocation, and outputs the control signal to the modulation unit 107.
[0059]
The control signal and pilot signal are modulated by modulation section 107, spread by spreading section 108, and output to multiplexing section 109.
[0060]
On the other hand, the downlink transmission data transmitted from the base station to the communication terminal is stored in the buffer 103 until communication resource allocation is determined. Downlink transmission data output from the buffer 103 is modulated by a modulation scheme that can be received by the communication terminal by the adaptive modulation unit 104, spread by a spreading code that can be received by the communication terminal by the adaptive spreading unit 105, and multiplexed by the multiplexing unit 109. Is output.
[0061]
In multiplexing section 109, the spread control signal and pilot signal are time-multiplexed at predetermined intervals on the spread downlink transmission data. The output signal of the multiplexing unit 109 is frequency-converted to a radio frequency by the transmission RF unit 110, and is wirelessly transmitted from the antenna 112 to each communication terminal via the duplexer 111.
[0062]
A signal wirelessly transmitted from the base station is received by the antenna 207 of each communication terminal, and frequency-converted to baseband by the reception RF unit 208 via the duplexer 206.
The control signal component of the baseband signal is despread by the despreading unit 211 and output to the CIR measurement unit 212 and the demodulation unit 213.
[0063]
Next, CIR measurement section 212 calculates CIR based on the pilot signal output from despreading section 211, and transmission rate calculation section 201 calculates a transmission rate that can be received with a desired quality based on CIR. The At the same time, the demodulation unit 213 demodulates the output signal of the despreading unit 211 and extracts information indicating a selectable transmission rate and information indicating allocation of communication resources.
[0064]
Here, in a communication terminal to which communication resources are allocated, the data component of the baseband signal is despread by adaptive despreading section 209, demodulated by adaptive demodulation section 210, and desired data is extracted.
[0065]
On the other hand, in a communication terminal to which communication resources are not allocated, a DRC signal is created again by the DRC signal creation unit 202 and transmitted to the base station. However, if a transmission rate that can be received with a desired quality is not an option, the creation of the DRC signal is stopped.
[0066]
In this way, when the traffic situation increases, the base station does not transmit data to the communication terminal at a low transmission rate by removing the low transmission rate from the options, and the transmission efficiency of the system is improved. Can be planned.
[0067]
Further, when the communication terminal cannot receive a service at the selected transmission rate, such as being in the vicinity of the cell edge, the DRC signal is not transmitted, so that power consumption can be reduced.
[0068]
In addition, if a base station exchanges traffic information with a base station in another cell and cooperates, a dynamic service area can be constructed, and a communication terminal that cannot receive a service at a selected transmission rate can provide a service. Other cells that can be received can be searched and handed over if necessary.
[0069]
In addition, if the base station exchanges traffic information with another system, a communication terminal that cannot receive the service at the selected transmission rate searches for another system that can receive the service, and performs handover if necessary. Even if the terminal cannot receive the service in the existing HDR system, it can receive the data transfer service in another system.
[0070]
In the above embodiment, a system has been described in which the transmission rate of transmission data is determined on the communication terminal side and communication resources are allocated on the base station side. However, the present invention is not limited to this, and transmission is performed on the base station side. It is also effective in a system that allocates communication resources by determining the data transmission rate. In this case, each communication terminal transmits information indicating the measured CIR to the base station.
[0071]
Moreover, although the case where the transmission rate which can communicate based on CIR was calculated was demonstrated in the said embodiment, this invention is not limited to this, The value which shows receiving quality other than CIR can also be used.
[0072]
In the above embodiment, the case where the pilot signal is time-multiplexed has been described. However, the present invention is not limited to this, and even when the pilot signal is code-multiplexed, the quality of the pilot signal is similarly measured. The transmission rate can be calculated.
[0073]
【The invention's effect】
As described above, according to the present invention, since the base station does not transmit data to the communication terminal at a low transmission rate, the transmission efficiency of the system can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a base station according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a communication terminal according to the embodiment. FIG. 3 uses a conventional HDR scheme. Diagram showing communication form 【Explanation of symbols】
101 transmission rate determination unit 102 allocation unit 103 buffer 104 adaptive modulation unit 105 adaptive spreading unit 106 control signal creation unit 107 modulation unit 108 spreading unit 109 multiplexing unit 201 transmission rate calculation unit 202 DRC signal creation unit 209 adaptive despreading unit 210 adaptive demodulation Unit 211 despreading unit 212 CIR measuring unit 213 demodulating unit

Claims (10)

Allocating means for allocating communication resources based on first information transmitted from each communication terminal apparatus in communication and indicating a downlink transmission rate that can be received at a desired quality by each of the communication terminal apparatuses ;
When the number of communication terminal devices that have transmitted the first information is greater than a predetermined threshold, it is determined that the traffic situation is increasing, and a transmission rate that can be selected according to whether the traffic situation is increasing is determined. A transmission rate determining means for determining;
Control information transmitting means for creating second information indicating allocation of communication resources and third information indicating selectable transmission rates and transmitting them to the communication terminal device;
Data transmission means for transmitting data to a specific communication terminal device in accordance with the allocation of communication resources ;
A base station apparatus comprising:   2. The base station apparatus according to claim 1, wherein the transmission rate determining means excludes a low transmission rate from the options when the traffic situation increases. The base station apparatus according to claim 1, wherein the transmission rate determining means sequentially changes the threshold value according to a distribution of the requested transmission rate. Allocating means for allocating communication resources based on first information transmitted from each communication terminal apparatus in communication and indicating a downlink transmission rate that can be received at a desired quality by each of the communication terminal apparatuses;
When the number of communication terminal devices that request a transmission rate lower than the first threshold is greater than the second threshold, it is determined that the traffic situation is increasing, and can be selected depending on whether the traffic situation is increasing A transmission rate determining means for determining a proper transmission rate;
Control information transmitting means for creating second information indicating allocation of communication resources and third information indicating selectable transmission rates and transmitting them to the communication terminal device;
Data transmission means for transmitting data to a specific communication terminal device in accordance with the allocation of communication resources;
A base station apparatus comprising: 5. The base station apparatus according to claim 4, wherein the transmission rate determining means sequentially changes at least one of the first threshold value and the second threshold value according to a distribution of the requested transmission rate. Transmission rate determining means detects the traffic information of neighboring cells, wherein when there is a margin in the capacity of the neighboring cells only, claim 1, wherein the removing low transmission rate from options to claim 5 The base station apparatus as described. The transmission rate determining means detects traffic information of another communication system providing a service in a neighboring area, and removes a low transmission rate from the options only when there is a margin in the capacity of the other communication system. The base station apparatus in any one of Claims 1-5 . Measurement means for measuring the reception quality of the signal transmitted from the base station apparatus according to any one of claims 1 to 7 ,
Transmission rate calculating means for calculating a transmission rate that can be received with desired quality based on the measured reception quality;
Demodulation means for demodulating the second information and the third information from the signal transmitted from the base station device;
Control information transmitting means for creating new first information and transmitting it to the base station apparatus only when the calculated transmission rate is selectable based on the third information;
Data receiving means for receiving data transmitted from the base station apparatus according to the second information ;
A communication terminal apparatus comprising: A communication method used in a base station apparatus,
An allocation step of allocating communication resources based on first information transmitted from each communication terminal apparatus in communication and indicating a downlink transmission rate that can be received by each of the communication terminal apparatuses with a desired quality;
When the number of communication terminal devices that have transmitted the first information is greater than a predetermined threshold, it is determined that the traffic situation is increasing, and a transmission rate determination that can be selected depending on whether or not the traffic situation is increasing A transmission rate determining step to perform,
A control information transmission step of creating second information indicating communication resource allocation and third information indicating selectable transmission rates and transmitting the third information to the communication terminal device;
A data transmission step of transmitting data to a specific communication terminal device according to the allocation of communication resources;
A communication method comprising: A communication method used in a base station apparatus,
An allocation step of allocating communication resources based on first information transmitted from each communication terminal apparatus in communication and indicating a downlink transmission rate that can be received by each of the communication terminal apparatuses with a desired quality;
If the number of communication terminal devices that have requested a transmission rate lower than the first threshold is greater than the second threshold, it is determined that the traffic situation is increasing and can be selected depending on whether the traffic situation is increasing A transmission rate determination step for determining a proper transmission rate;
A control information transmission step of creating second information indicating communication resource allocation and third information indicating selectable transmission rates and transmitting the third information to the communication terminal device;
A data transmission step of transmitting data to a specific communication terminal device according to the allocation of communication resources;
A communication method comprising:

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