JP2002374205A - Radio communication device and method of controlling transmission rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of controlling transmission rate that can properly control base station transmission power for a mobile station, without being affected by the environment and the transmission rate of the mobile station. SOLUTION: The communication terminal equipment measures reception quality and reports the measured result to the base station equipment, and the base station apparatus switches the transmission rate, based on the reported result of the reception quality. In this way, the transmission rate is switched being set as the starting time, when the reception quality of the communication terminal equipment deteriorates. Furthermore, the transmission rate is switched so that the amount of interference with others is within the allowable range, according to the channel condition between the communication terminal equipment and the base station equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication apparatus for making a transmission rate variable and a transmission rate control method.

[0002]

2. Description of the Related Art A conventional wireless communication apparatus is described in the document "D.
A Study on Transmission Power Control Method Following Instantaneous Value Fluctuation in S-CDMA Downlink Channel (IEICE Technical Report AP96)
-148, EMCJ96-83, RCS96-162, MW96-188 (1997-02) ". This document describes a transmission power control method in CDMA. Hereinafter, this description will be described. I do.

In transmission power control, S indicating reception quality is used.
The IR measurement and the increase / decrease of the transmission power take one slot period (0.
625 ms). In this case, the measured SIR
Is compared with the target SIR. If the measured value is large, a command to reduce the transmission power is sent to the base station (transmitting side). If the measured value is small, a command to increase the transmission power is sent to the base station. The base station increases or decreases the transmission power accordingly.

The base station controls the outer loop in consideration of the fact that the target SIR for obtaining a required quality (FER: Frame Error Rate) differs depending on the environment of the mobile station. Specifically, first, FER is measured from the decoded data. This is compared with the target FER every several frames. If the measured value is large, the target SIR is raised, and if the measured value is small, the target SIR is lowered.

In the prior art, the SI measured at the mobile station is
The transmission power control command is sent to the transmission side based on R, and the transmission power control is performed by changing the target SIR by outer loop control.

[0006]

However, the prior art has the following problems. That is, the target SIR may increase depending on the environment and the transmission speed of the mobile station, and the reception SIR may decrease due to fading or the like. At this time, the mobile station instructs the base station to increase the transmission power in order to bring the reception SIR closer to the target SIR, so that the transmission power of the base station with respect to the mobile station becomes very large, and the amount of interference with other mobile stations increases. May increase unacceptably.

[0007] The present invention has been made in view of the above points, and a radio communication apparatus and a transmission apparatus capable of appropriately controlling the base station transmission power to a mobile station without being affected by the environment or the transmission speed of the mobile station. It is an object to provide a rate control method.

[0008]

The gist of the present invention is to increase the transmission rate and transmit more data when the line condition is good, and to reduce the data transmission amount by lowering the transmission rate when the line condition is bad. That is. That is, the present invention is to perform transmission power control based on reception quality information from a communication partner, and to control a transmission rate of a transmission signal according to an average value of transmission power.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radio communication apparatus according to a first aspect of the present invention comprises an average transmission power calculating means for calculating an average transmission power, an average transmission power, a predetermined allowable transmission power, And a transmission rate control unit that changes the transmission rate according to the comparison result of the comparison unit.

According to a second aspect of the present invention, there is provided a radio communication apparatus, comprising: a radio transmission unit; a radio reception unit; and a transmission unit for increasing or decreasing the transmission power of the radio transmission unit according to transmission power control information received by the radio reception unit. Power control means, average transmission power calculation means for calculating an average value of transmission power of the wireless transmission means, allowable transmission power holding means for holding a predetermined allowable transmission power value, and an average value of the transmission power and the allowable value. A configuration including a comparing unit that compares the transmission power value and a transmission rate control unit that changes the transmission rate according to the comparison result of the comparing unit is adopted.

In a wireless communication apparatus according to a third aspect of the present invention, the transmission rate control means controls the transmission rate according to an average value of transmission power measured in units of at least one frame. take.

With these configurations, the base station can perform transmission power control based on the reception quality measured by the communication terminal apparatus and switch the transmission rate of the base station based on the average value of the transmission power. The transmission power and the transmission rate of the base station apparatus to the communication terminal apparatus can be more appropriately controlled without being affected by the environment and the transmission speed of the terminal apparatus.

A wireless communication apparatus according to a fourth aspect of the present invention employs a configuration in which the transmission rate control means controls a transmission rate by changing a spreading factor.

With this configuration, it is possible to control the transmission power in accordance with the situation where the interference amount varies depending on the spreading factor, and it is possible to control the transmission rate by the spreading factor.

[0015] A wireless communication apparatus according to a fifth aspect of the present invention employs a configuration in which the allowable transmission power value of the allowable transmission power holding means is set by a control means located in an upper layer.

[0016] In the radio communication apparatus according to a sixth aspect of the present invention, the transmission rate control means may be configured to perform transmission when the comparison result of the comparison means indicates that the average value has reached an allowable transmission power value. Use a configuration that lowers the rate.

With these configurations, the present invention can be applied to a system in which transmission rate control is performed by an upper station.

A transmission rate control method according to a seventh aspect of the present invention is a transmission rate control method usable for a radio communication apparatus having a radio transmission means and a radio reception means, wherein the transmission power is controlled by the radio reception means. Receiving the control information; increasing and decreasing the transmission power of the wireless transmission means according to the transmission power control information; calculating an average value of the transmission power of the wireless transmission means; Comparing the transmission rate with the allowed transmission power value, and changing the transmission rate according to the comparison result.

According to this method, the base station can perform transmission power control based on the reception quality measured by the communication terminal apparatus and switch the transmission rate of the base station based on the average value of the transmission power. The transmission power and the transmission rate of the base station device to the communication terminal device can be controlled more appropriately without being affected by the device environment and the transmission speed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. (Embodiment 1) FIG.1 is a block diagram showing a configuration of a base station apparatus according to Embodiment 1 of the present invention. In this base station apparatus, the signal transmitted by antenna 101 is transmitted to antenna duplexer 10 for using the same antenna for transmission and reception.
2 to the receiving RF circuit 103. In the reception RF circuit 103, the reception signal is amplified and frequency-converted to an intermediate frequency or a baseband frequency.

The frequency-converted signal is supplied to a demodulation circuit 104
Is demodulated. The demodulation result is sent to the separation circuit 105,
The separation circuit 105 separates the received data into a signal for controlling transmission rate switching.

The transmission rate switching control circuit 106 sends a transmission rate switching signal to the transmission frame creation circuit 107 based on the received control signal. The operation of the transmission rate switching control circuit will be described later.

For transmission, the transmission data is transmitted to the modulation circuit 1
The signal is modulated at 08 and sent to the transmission RF circuit 109. In the transmission RF circuit 109, the transmission data is frequency-converted and further amplified. This transmission signal is transmitted from the antenna 101 through the antenna duplexer 102.

FIG. 2 is a block diagram showing a configuration of a communication terminal apparatus for performing wireless communication with the base station apparatus according to Embodiment 1 of the present invention.

The signal received by the antenna 201 is sent to a reception RF circuit 203 through an antenna duplexer 202 for using the same antenna for transmission and reception, where it is amplified and further converted to an intermediate frequency or a baseband frequency. Is done. The frequency-converted signal is supplied to the demodulation circuit 20
4 demodulated. At the same time, the output signal of the receiving RF circuit is S
The signal is sent to an IR (reception quality) measurement circuit 205, where the reception quality is measured.

The reception quality includes, for example, reception electric field strength, desired wave reception power, reception signal to interference power ratio (SI
R), ratio of received signal power to interference power + noise power (Signal-t
o-Interference pulse Noise Ratio (hereinafter abbreviated as SINR). The reception electric field strength is obtained by measuring the power of the reception RF. The use of the received electric field strength simplifies the circuit configuration. Further, it can be used in an environment where there is no interference wave.

The desired wave reception power is measured by multiplying the reception signal by a known signal. In this case, when an interference wave exists, the reception power of the desired signal and the interference signal are reported only by the received electric field strength. It may not be. For this reason, in order to measure and report the reception power of a desired signal required by the terminal, it is preferable to use SINR, which is the most reliable information as an index for determining error rate characteristics, as reception quality.

FIG. 3 shows a circuit for measuring the reception power of the desired wave.
This circuit extracts the known pattern part of the received signal,
A complex conjugate operation is performed on a known pattern of the base station by a complex conjugate circuit 302, and a complex multiplication circuit 301 performs complex multiplication of the known pattern portion of the received signal and the known pattern obtained by performing the complex conjugate operation,
The position of the desired reception signal on the complex plane (the position of the black circle in FIG. 5) is calculated, and the power measurement circuit 303 is calculated from the calculation result.
Measure the power at.

FIG. 4 shows a circuit for measuring the SINR.
This circuit extracts the known pattern part of the received signal,
A complex conjugate operation is performed on the known pattern of the base station by the complex conjugate circuit 402, and the known pattern portion of the received signal is complex-multiplied by the complex conjugate operation of the known pattern by the complex multiplication circuit 401,
The position of the desired reception signal on the complex plane (the position of the black circle in FIG. 5) is calculated, and the power is measured from the calculation result. Further, in the interference power + noise power measuring circuit 404, the average of the sum of squares of the vector between the position of each received signal (the position of the white circle in FIG. 5) and the position of the desired received signal (the position of the black circle in FIG. 5). The interference power + noise power is measured from the value. Also,
The desired power is measured by the desired power measurement circuit 403 from the calculation result. Next, in the ratio calculation circuit 405, the interference power + noise power measurement circuit 404 and the desired power measurement circuit 40
From the output of No. 3, the ratio between the two is calculated. Thereby, SIN
Calculate R.

The reception quality measurement results calculated by these methods are sent to the multiplexing circuit 206. The multiplexing circuit 206 allocates transmission data and reception quality measurement results to transmission slots. Such transmission data is modulated by the modulation circuit 207,
The frequency is converted and amplified by the transmission RF circuit 208. Then, the transmission signal is transmitted from antenna 201 through antenna duplexer 202.

Here, reporting of transmission rate switching information from the communication terminal apparatus to the base station apparatus will be described. There are two types of reporting: a method that reports constantly, and a method that reports when necessary. In the former method, the transmission rate can be switched with high accuracy because the reporting is always performed, but the communication amount increases.

In the case of voice communication or the like, as shown in FIG. 6, voice information (message) and control information are often multiplexed and transmitted in one slot. Therefore, it is possible to always report in voice communication and low-speed data communication.

The latter method reports only when necessary, so that the communication amount is small. This method is preferably used for packet communication for realizing high-speed data communication. In packet communication, information generated in a burst is transmitted in a short time. For this purpose, FIGS. 7A and 7B
As shown in (1), the control information is not multiplexed in the slot, and a flag indicating whether it is a message or control information is used. FIG. 7A shows a case where a flag is set for a message, and FIG. 7B shows a case where a flag is set for control information.

Next, the timing at which the transmission rate is switched will be described. There are the following four methods for the transmission rate switching timing.

First, the first method will be described with reference to FIG. When the reception quality is measured on the communication terminal device side, the reception quality may suddenly deteriorate. In a mobile communication environment, for example, when it becomes impossible to secure line-of-sight communication called shadowing, the reception electric field intensity decreases by several tens of dB rapidly. Such a situation is monitored, and a report is made at the timing when the reception quality suddenly decreases. The base station device switches the transmission rate triggered by the reception quality report. When the reception quality measured on the communication terminal side is improved at the request of the base station side or periodically, the base station apparatus switches the transmission rate and restores the transmission rate. The timing at which the reception quality suddenly deteriorates or the timing at which the reception quality improves can be detected, for example, by performing a threshold determination on the reception quality such as the reception electric field strength.

Next, the second method will be described with reference to FIG. In the base station device, the reception quality is measured. If the reception quality suddenly deteriorates, it is considered that line-of-sight communication called shadowing cannot be secured. Shadowing is determined by the position of the antenna of the communication terminal device and the antenna of the base station device, and is not affected by the carrier frequency difference. Therefore, in such a case, it is considered that the reception quality is rapidly deteriorated even in the communication terminal device. Therefore, a request for reporting the reception quality is transmitted from the base station apparatus to the communication terminal apparatus. The communication terminal device measures the reception quality and reports it to the base station device. The base station device performs transmission rate switching control according to the reception quality report value. When the reception quality measured on the communication terminal side is improved at the request of the base station side or periodically, the base station apparatus switches the transmission rate and restores the transmission rate.
The timing at which the reception quality suddenly deteriorates or the timing at which the reception quality improves can be detected, for example, by performing a threshold determination on the reception quality such as the reception electric field strength.

Next, a third method will be described with reference to FIG. In the communication terminal device, when there is an error in the received message, a retransmission request is made. In the base station apparatus, a report request of the reception quality is transmitted from the base station apparatus to the communication terminal apparatus at a timing when the retransmission request is made from the communication terminal apparatus. The communication terminal measures the reception quality and reports it to the base station. The base station device performs transmission rate switching control according to the reception quality report value. For example, when the reception quality report value measured by the communication terminal device is lower than a predetermined value, the transmission rate is switched. Upon request from the base station,
Alternatively, periodically, when the reception quality measured by the communication terminal side is improved, the base station apparatus switches the transmission rate to restore the original transmission rate. The timing at which the reception quality suddenly deteriorates or the timing at which the reception quality improves can be detected, for example, by performing a threshold determination on the reception quality such as the reception electric field strength.

Next, a fourth method will be described with reference to FIG. The base station device monitors its own transmission power. Although the base station apparatus controls the transmission power based on the transmission power control signal sent from the communication terminal apparatus,
When the transmission quality from the base station device to the communication terminal device deteriorates, the communication terminal device requests an increase in transmission power. If it is determined that this request is excessive transmission power in consideration of the amount of interference with others, the base station device performs transmission rate switching control. The determination that the transmission power is excessive can be made by, for example, a threshold determination. When a predetermined transmission power allowance is secured, the base station switches the transmission rate to return the transmission rate to the original one. This predetermined transmission power allowance is appropriately determined according to the control amount of the transmission rate. For example, if the transmission rate is reduced by half,
The transmission rate is switched when an allowable amount of at least 3 dB can be secured.

By combining some of the above four types of methods, it is possible to eliminate delays in transmission rate switching control and perform fine control.

As described above, the result of measuring the reception quality of the downlink signal transmitted from the base station apparatus shown in FIG. 1 is measured by the communication terminal apparatus shown in FIG. 2 and reported to the base station on the uplink. The base station switches the transmission rate based on the reception quality measurement result measured by the communication terminal apparatus received on the uplink.

Here, the operation of the transmission rate switching control circuit will be described in detail. FIG. 12 is a flowchart of the transmission rate switching control circuit. In ST11, the base station apparatus compares the reception quality measurement result reported from the communication terminal apparatus with threshold value 1. Here, the reception quality is SI
The case of R will be described, but the same applies even if the reception quality is the reception field strength, the desired wave reception power, and the SINR. This threshold 1 is set according to the transmission rate.
In the DMA communication system, it is set according to the spreading factor or the number of multiplexed codes.

When the reception quality measurement result (SIR) is larger than the threshold value 1, the transmission rate is used as it is. SI
If R is smaller than the threshold value 1, it is determined that the line state is bad, and the transmission rate is switched to a 1/2 transmission rate (ST12).

As shown in FIG. 13, in the base station apparatus, the reception quality measurement result reported from the communication terminal apparatus is compared with threshold value 1 (ST21). SIR using the transmission rate of
Is smaller than the threshold 1, the transmission rate is switched to a transmission rate at which the SIR is larger than the threshold 1 (ST22). CDM
In A, the spreading factor is switched. For this reason, SIR
Exceeds the threshold value 1, so that the fluctuation of the reception quality can be controlled more accurately. As a result, the reception quality of the communication partner can be improved even when the state of the communication channel with the communication partner suddenly deteriorates, and the transmission power is reduced due to the lower target reception quality, thereby reducing the amount of interference with others. can do. Therefore, the improvement effect by the transmission rate switching can be improved.

As shown in FIG. 14, in the base station apparatus, the reception quality measurement result reported from the communication terminal apparatus is compared with threshold value 2 (ST 31). SIR using the transmission rate of
Is larger than the second threshold, it is determined that the line condition is good, and the transmission rate is switched to a double transmission rate (a 1/2 spreading factor) (ST32). Here, the threshold 2 corresponds to a double transmission rate, and the threshold 1
Set larger. Thus, when the line condition is good, the transmission rate is increased to transmit as much data as possible. That is, when the state of the communication path with the communication partner is good, higher-speed transmission is possible while maintaining the reception quality of the communication partner. Since the transmission power does not increase, the amount of interference with others does not increase.

As shown in FIG. 15, threshold value n is set (ST41), and the base station apparatus compares the reception quality measurement result reported from the communication terminal apparatus with threshold value n (ST42). If SIR is smaller than threshold n, threshold n
Is changed to the threshold value n + 1 corresponding to the next highest transmission rate (ST43). If the SIR is larger than the threshold value n, the n-th highest transmission rate (spreading factor) is set (ST4).
4). That is, the transmission rate is switched so that the SIR is between two thresholds n and n + 1 corresponding to the two transmission rates. Note that the threshold value n corresponds to the nth highest transmission rate, and is larger than the threshold value n + 1. In this case, the fastest transmission is possible under the condition that the reception quality is satisfied. This makes it possible to more accurately control the transmission rate according to the line condition.

According to such a method, the transmission rate of the base station can be switched based on the reception quality of the communication terminal device. By this means, it is possible to avoid a situation in which the reception quality of the communication partner continues to be poor, and to reduce the transmission power because the target reception quality is reduced, thereby reducing the amount of interference with others. Therefore, it is possible to appropriately control the base station transmission power for the communication terminal device without being affected by the environment and the transmission speed of the communication terminal device.

(Embodiment 2) FIG.16 is a block diagram showing a configuration of a base station apparatus according to Embodiment 2 of the present invention.

In this base station apparatus, the antenna 10
The signal received at 1 is sent to the reception RF circuit 103 through the antenna duplexer 102 for using the same antenna for transmission and reception. In the reception RF circuit 103, the reception signal is amplified and frequency-converted to an intermediate frequency or a baseband frequency.

The frequency-converted signal is supplied to the demodulation circuit 104
Is demodulated. The demodulation result is sent to the separation circuit 105,
The separation circuit 105 separates the reception data and the transmission power control signal.

The transmission rate switching control circuit 106 sends a transmission rate switching signal to the transmission frame creation circuit 107 based on the transmission power control signal. The operation of the transmission rate switching control circuit will be described later.

For transmission, the transmission data is transmitted to the modulation circuit 1
The signal is modulated at 08 and sent to the transmission RF circuit 109. The transmission RF circuit 109 frequency-converts the transmission data. This transmission signal is transmitted to the antenna 101 through the antenna duplexer 102.
Send from.

FIG. 17 is a block diagram showing a configuration of a communication terminal apparatus for performing wireless communication with a base station apparatus according to Embodiment 2 of the present invention.

The signal received by the antenna 201 is sent to a reception RF circuit 203 through an antenna duplexer 202 for using the same antenna for transmission and reception, amplified there, and further converted to an intermediate frequency or a baseband frequency. Is done. The frequency-converted signal is supplied to the demodulation circuit 20
4 demodulated. At the same time, the output signal of the receiving RF circuit is
The signal is sent to the transmission power control value calculation circuit 255, where the transmission power control signal is determined.

The transmission power control signal includes, for example, received electric field strength, desired wave received power, received signal power to interference power ratio (SIR), received signal power to interference power + noise power ratio (Si
gnal-to-Interference pulse Noise Ratio). Further, the amount of information to be transmitted as a transmission power signal is two kinds of information of increasing / decreasing transmission power,
In some cases, the amount of control is increased / maintained / reduced, and the amount of control is set more finely than in the case of three types of information.

First, the case where the control information is two information will be described. If it is based on the received electric field strength, the power of the received RF is measured. Then, when the measured power is larger than the threshold, a control signal is generated so as to reduce the transmission power from the base station, and when the measured power is smaller than the threshold, the transmission power from the base station is increased. Generate control signals. Such a method based on the received electric field strength has the simplest circuit configuration. Further, it can be used in an environment where there is no interference wave.

When the power is based on the desired wave reception power, the measurement is performed by multiplying the reception signal by a known signal. When an interference wave exists, there is a possibility that the reception power of the desired wave and the reception power of the interference wave may not be reported by the received electric field strength alone. For this reason,
It is necessary to measure and report the reception power of the desired signal required by the communication terminal device. Therefore, it is preferable to use SINR, which is the most reliable information as an index for determining the error rate characteristic, as the reception quality.

FIG. 18 shows a circuit for measuring the reception power of the desired wave. In this circuit, a known pattern portion of a received signal is extracted, a complex conjugate operation is performed on a known pattern of the base station by a complex conjugate circuit 302, and a complex multiplication is performed by a complex multiplication circuit 301.
The position of the desired received signal on the complex plane (the position of the black circle in FIG. 5) is calculated, and the power measurement circuit 303 measures the power based on the calculation result. Then, the comparison circuit 1801
When the measured power is larger than the threshold 3, a control signal is generated so as to reduce the transmission power from the base station, and when the measured power is smaller than the threshold 3, the transmission power from the base station is increased. To generate a control signal.

FIG. 19 shows a circuit for measuring the SINR. In this circuit, a known pattern portion of a received signal is extracted, a complex conjugate operation is performed on a known pattern of the base station by a complex conjugate circuit 402, and a complex multiplication is performed by a complex multiplication circuit 401.
The position of the desired reception signal on the complex plane (the position of the black circle in FIG. 5) is calculated, and the power is measured based on the calculation result. Further, in the interference power + noise power measurement circuit 404, interference is obtained from the average value of the sum of squares of the vector of each received signal (the position of the white circle in FIG. 5) and the position of the desired received signal (the position of the black circle in FIG. 5). Measure power + noise power. Also,
The desired power is measured by the desired power measurement circuit 403. Next, the ratio calculation circuit 405 calculates a ratio from the outputs of the interference power + noise power measurement circuit 404 and the desired power measurement circuit 403. Then, when the power ratio measured by the comparison circuit 1901 is larger than the threshold value 3, a control signal is generated so as to reduce the transmission power from the base station. When the measured power ratio is smaller than the threshold value 3, the control signal is generated from the base station. A control signal is generated so as to increase the transmission power of.

Next, the case where the control information is three information will be described. In the case of three pieces of information, threshold 3 and threshold 4 larger than threshold 3 are used as thresholds. When the measured power ratio is smaller than the threshold value 3, control information for increasing the transmission power from the base station is generated. When the measured power ratio is larger than threshold value 3 and smaller than threshold value 4, control information is generated so as to keep the transmission power from the base station as it is. If the measured power ratio is larger than threshold 4, control information is generated so as to reduce the transmission power from the base station.

Further, when the number of pieces of control information is four or more, the number of thresholds is set to (the number of control information -1), and the control information that has been finely divided is determined by threshold determination based on the magnitude relation of a plurality of thresholds. .

The transmission power control information calculated by these methods is sent to the multiplexing circuit 206. The multiplexing circuit 206 allocates transmission data and transmission power control information to transmission slots. Such transmission data is modulated by the modulation circuit 207 and the transmission R
The frequency is converted and amplified by the F circuit 208. This transmission signal is transmitted to the antenna 201 through the antenna duplexer 202.
Send from.

As described above, the communication terminal apparatus shown in FIG. 17 generates the transmission power control signal based on the reception quality of the downlink signal transmitted from the base station apparatus shown in FIG. Report to In the base station device,
The transmission rate is switched based on the transmission power control signal measured by the communication terminal apparatus received on the uplink.

Here, the operation of the transmission rate switching control circuit will be described in detail. FIG. 20 is a flowchart showing transmission rate switching control. The base station device estimates reception quality by integrating transmission power control information reported from the communication terminal device (ST51), and compares it with threshold value 1 (ST52). This threshold 1 is set according to the transmission rate, but in the CDMA communication system, it is set according to the spreading factor or the number of multiplexed codes.

When the reception quality estimation value (SIR estimation value) is
If it is larger, it is determined that the line condition is good, and the same transmission rate is used. If the SIR estimated value is smaller than the threshold value 1, it is determined that the line condition is bad,
The transmission rate is switched to 1/2 transmission rate (double spreading rate) (ST53).

As described above, since the transmission rate is switched based on the channel estimation result, the amount of interference with others can be reduced. Further, since the transmission power bit is used for channel estimation, no special control information is required for transmission rate control, and the amount of information transmitted from a communication partner can be reduced.

Further, as shown in FIG. 21, the base station apparatus estimates reception quality by integrating transmission power control information reported from the communication terminal apparatus (ST61),
Compared to threshold 1 (ST62), the SIR estimated value
If it is larger than the threshold, it is determined that the line condition is good, and the transmission rate is used as it is. If the estimated SIR value is smaller than the threshold 1, the line condition is determined to be bad, and the SIR becomes larger than the threshold 1. The transmission rate may be switched (ST63). As a result, it is possible to more accurately control the fluctuating reception quality. That is, even when the state of the communication path with the communication partner is rapidly deteriorated, the reception quality of the communication partner can be improved, and the transmission power is reduced because the target reception quality is reduced, so that the amount of interference with other components is reduced. be able to. Therefore, the improvement effect by the transmission rate switching can be improved.

As shown in FIG. 22, in the base station apparatus, the reception quality is estimated by integrating transmission power control information reported from the communication terminal apparatus (ST71), and is compared with threshold value 2 (ST72). If the SIR estimated value is smaller than the threshold 2, it is determined that the line state is bad, and the transmission rate is used as it is. If the SIR estimated value is larger than the threshold 2, the line state is determined to be good. Alternatively, the transmission rate may be switched to a double transmission rate (1/2 spreading rate) (ST73). Note that threshold 2 corresponds to twice the transmission rate and is larger than threshold 1.

As described above, when the line condition is good, the transmission rate is increased to transmit as much data as possible. That is, when the state of the communication path with the communication partner is good, higher-speed transmission is possible while maintaining the reception quality of the communication partner. Since the transmission power does not increase,
The amount of interference with others does not increase.

Further, as shown in FIG. 23, the base station apparatus estimates reception quality by integrating transmission power control information reported from the communication terminal apparatus (ST81),
An initial value (n = 1) of the threshold value n is set (ST82), and is compared with the threshold value n (ST84). If the SIR estimated value is smaller than the threshold n, the threshold n is changed to the threshold n + 1 which is the next highest transmission rate (ST83). If the SIR estimated value is larger than the threshold value n, the n-th highest transmission rate (spreading factor) is set (ST85). That is, the SIR estimated values are two threshold values n and n + corresponding to the two transmission rates.
The transmission rate is switched to a value between 1. Note that the threshold value n corresponds to the n-th highest transmission rate, and the threshold value n + 1
Greater than. In this case, the fastest transmission is possible under the condition that the reception quality is satisfied. This makes it possible to more accurately control the transmission rate according to the line condition.

The operation of another transmission rate switching control circuit will be described. For example, as shown in FIG.
In the base station apparatus, required transmission power is determined based on transmission power control information reported from the communication terminal apparatus. This transmission power is compared with threshold value 4 (ST9).
1).

The threshold value 4 is determined according to the limit value of the transmitter or the amount of interference caused by increasing the transmission power. The threshold value 4 is set according to the transmission rate. In the CDMA communication system, the threshold value 4 is set according to the spreading factor or the number of multiplexed codes. That is,
In the case of transmission with 16-fold spreading and 256-fold spreading, there is a 16-fold difference in the spreading factor, so the transmission power threshold at 16-fold spreading is 16 times the transmission power threshold at 256-fold spreading.
The same can be said for the number of multiplex codes.

In ST91, when the transmission power is smaller than threshold value 4, the transmission rate is used as it is. If the transmission power is higher than the threshold value 4, it is determined that interference with others is large, and the transmission rate is switched to a 伝 送 transmission rate (double spreading factor) (ST92). This enables optimal or fastest transmission under the condition that the amount of interference with others is within an allowable range.

As shown in FIG. 25, the required transmission power is determined in the base station apparatus based on the transmission power control information reported from the communication terminal apparatus. This transmission power is compared with threshold 4 (ST101). If the transmission power is lower than threshold 4, the transmission rate is used as it is, and if the transmission power is higher than threshold 4, it is determined that interference with others is large. Judgment is made to switch to a transmission rate (spreading factor) at which the transmission power becomes smaller than threshold value 5 (ST102).
Thereby, it is possible to suppress the occurrence of an excessive amount of interference.

Further, as shown in FIG. 26, the required transmission power is determined in the base station apparatus based on the transmission power control information reported from the communication terminal apparatus. This transmission power is compared with the threshold 5 (ST111). If the transmission power is higher than the threshold 5, the transmission rate is used as it is, and if the transmission power is lower than the threshold 5, it is determined that interference with other components is small. By judging, the transmission rate may be switched to a double transmission rate (１ ／ spreading factor) (ST11).
2). Here, the threshold value 5 corresponds to a double transmission rate and is smaller than the threshold value 4.

As shown in FIG. 27, threshold value n is set (ST121), and the base station apparatus compares the transmission power based on the transmission power control information reported from the communication terminal apparatus with threshold value n (ST123). ). If the transmission power is larger than threshold value n, threshold value n is changed to threshold value n + 1 which is the next highest transmission rate (ST122). Transmission power is threshold n
If smaller, the nth fastest transmission rate (spreading factor)
Is set (ST124). That is, the transmission rate is switched so that the transmission power is between two thresholds n and n + 1 corresponding to the two transmission rates. Note that the threshold value n corresponds to the nth highest transmission rate and is smaller than the threshold value n + 1. In this case, the highest speed transmission is possible under the condition that the amount of interference with others is suppressed within a certain range.

The transmission power setting method of the base station is as follows. First, each time the transmission rate is switched, transmission is performed at the transmission power before switching, and second, the transmission power is reduced by a fixed value from the transmission power before switching. There is a transmission method, and thirdly, a transmission method in which the transmission power is increased by a certain value from the transmission power before switching.

The first method is effective for surely improving the communication quality for the terminal. In the configuration of this embodiment, the transmission power control signal input to the transmission rate switching control circuit 106 may be sent to the transmission RF circuit 109 as it is. In the transmission RF circuit 109,
The transmission power is controlled up and down based on the transmission power control signal.

The second method is a method of setting a value by subtracting a certain value from the transmission power when switching the transmission rate.
This is because, when the line is improved for a terminal, the transmission power has a large value, which may cause a large interference with another terminal. In the configuration of this embodiment, the transmission rate switching control circuit 1
It is sufficient to change the transmission power control signal input to the control signal 06 to a control signal that reduces the transmission power by a certain value when the transmission rate is switched. The transmission RF circuit 109 controls the transmission power up and down based on the transmission power control signal.
At this time, the transmission power control amount integrated value also needs to be reduced by a certain value.

The third method is a method for increasing the transmission power within a range where the amount of interference with others is allowable, and is effective for improving the communication quality. In the configuration of this embodiment, the transmission power control signal input to the transmission rate switching control circuit 106 may be changed to a control signal that increases the transmission power by a certain value when the transmission rate is switched. At this time, the transmission power control amount integrated value also needs to be increased by a certain value.

For the constant value to be reduced, for example,
In the MA system, for example, by reducing the transmission by 3 dB, it becomes possible to increase the number of communication terminal devices communicating with the same spreading factor by one.

Further, the reception quality information may be reported from the communication terminal device together with the transmission power control information by the method described in the first embodiment. The method of reporting from the communication terminal device to the base station device and its timing are the same as those in the first embodiment.

The transmission rate switching control is normally performed based on the integrated value of the transmission power control information. If the reception quality of the communication terminal device suddenly deteriorates, the reception quality information is transmitted from the communication terminal device. It reports to the base station apparatus and performs transmission rate switching control in the base station apparatus. Also, at the timing when a request for retransmission of ARQ control information or the like from the communication terminal device occurs in the base station device, a request for measuring reception quality is sent to the communication terminal device, the reception quality is measured by the communication terminal device, and the base station device Report. The base station device performs a transmission rate switching process based on the reported reception quality.

Next, control between layers of the transmission rate control method described in the first and second embodiments will be described. FIG. 28 is a diagram for explaining transmission rate control between layers.

In this control, as shown in FIG. 28, the allowable transmission power (P _allow ) set in the radio resource control (RRC) layer in layer 3 is sent to layer 1 (physical layer). In layer 1, the allowable transmission power (P _allow )
Is compared with the average transmission power. Then, a message (MPHY-STATUS) such as “reached the allowable transmission power”, “exceeded the allowable transmission power”, or “XdB lower than the allowable transmission power” is transmitted from the layer 1 to the layer 2 medium access control (MAC). A) shown in the layer. Note that the allowable transmission power is appropriately set by the radio resource control layer (Layer 3) according to the system load such as the traffic situation.

Here, the message that "the transmission power has reached the allowable transmission power" or "the transmission power has exceeded the allowable transmission power" indicates that it is necessary to reduce the transmission rate by judging that the line condition is bad. Further, a message "XdB lower than the allowable transmission power" indicates that the line state is restored and the transmission rate can be increased.

The specific control will be described with reference to FIG. Here, the case of the downlink will be described.
First, the radio resource control layer monitors downlink conditions,
The initial transmission rate of the downlink is determined by negotiation between the radio resource control layer (layer 3) and the medium access control layer (layer 2). After that, the communication starts.

During communication, in ST131, in layer 1, the average transmission power (P _ave ) of at least one frame is monitored. The transmission rate is controlled according to this line condition.

First, the average transmission power (P _ave ) and the allowable transmission power (P _allow ) are compared, and the difference between them (D = P
_allow −P _ave ) is required. Then, in ST132,
It is determined whether the average transmission power (P _ave ) exceeds the allowable transmission power (P _allow ). If the average transmission power (P _ave ) exceeds the allowable transmission power (P _allow ), ST133
, A message indicating that "the allowable transmission power has been reached" or "the allowable transmission power has been exceeded" is shown.

According to this message, the transmission rate is reduced in the medium access control layer (layer 2), and in layer 1, the total transmission power is reduced. This reduces interference with other communication terminals.

If average transmission power (P _ave ) does not exceed allowable transmission power (P _allow ), it is determined in ST 134 whether or not the difference is equal to or more than a predetermined amount (P _step ). This P _step is a power step corresponding to the difference between the changed transmission rate and the original transmission rate when the transmission rate is lowered.

If the difference (D) between the average transmission power (P _ave ) and the permissible transmission power (P _allow ) is smaller than a predetermined amount (P _step ), the transmission rate remains unchanged. If the difference (D) between the average transmission power (P _ave ) and the allowable transmission power (P _allow ) is larger than a predetermined amount (P _step ), ST
At 135, layer 1 is “XdB above allowable transmission power.
Low "message. Then, in accordance with this message, the transmission rate is increased in the medium access control layer (layer 2), and in layer 1, the total transmission power is increased within the range of X dB. As a result, the transmission signal that has been buffered due to the reduced transmission rate can be transmitted quickly.

In FIG. 29, only the determination of “increase”, “as is”, and “decrease” of the transmission rate is made. However, the present invention is not limited to this. Can be.

Next, a case where the above-described transmission rate control is actually performed will be described. In the existing transmission rate variable method, the downlink is burst transmission, and the uplink is continuous transmission. Therefore, the transmission rate is changed accordingly. That is, on the downlink, the transmission power itself is not changed, for example, transmission is performed only in the first half of the frame. The transmission rate is
The medium access control layer (layer 2) selects from the rate set designated by the radio resource control layer (layer 3). At this time, the physical layer (layer 1) creates and adds a word indicating the current transmission rate as instructed by the medium access control layer (layer 2).

If the above-mentioned transmission rate control is performed separately in each base station, an agreement is required at the time of diversity handover. For example, a method in which all base stations switch to a specific transmission rate in negotiation in an upper layer, a method in which transmission rate control is not performed during diversity handover, and the like can be considered.

In the above description, the case where the parameter monitored at layer 1 is the transmission power is described, but the parameter monitored at layer 1 is FE.
R, SIR, interference power, etc. can be used.

In the above description, the transmission rate control shown in FIG. 29 is performed on the downlink, but the transmission rate control shown in FIG. 29 can also be applied to the uplink. In the case of the downlink, it is used for the purpose of reducing interference with others, but in the case of the uplink, in addition to the case of reducing interference, it is also necessary to reduce power consumption or restrict hardware. Applies when there is.

In Embodiments 1 and 2, FIG.
2 and FIG. 17 are communication terminal apparatuses, but in the present invention, the apparatus shown in FIG. 1 and FIG. This is also applicable to a case where the terminal device is a terminal device and the devices shown in FIGS. 2 and 17 are base station devices.

In the first and second embodiments, the case where the transmission rate is doubled or halved is described. However, in the present invention, the transmission rate is set to other values depending on various conditions. It is also possible to have a magnification of.

The present specification is based on Japanese Patent Application No. 10-107300, the entire contents of which are incorporated herein.

[0100]

As described above, according to the present invention, for example, in a base station, transmission power control is performed based on the reception quality measured by a mobile station, and the transmission rate of the base station is determined based on an average value of the transmission power. Can be switched. As a result, the transmission power and the transmission rate of the base station apparatus to the mobile station can be more appropriately controlled without being affected by the environment and the transmission speed of the mobile station.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a base station apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a communication terminal device that performs wireless communication with the base station device according to the above-described embodiment.

FIG. 3 is a block diagram for explaining a method of measuring a desired wave reception power in the communication terminal apparatus.

FIG. 4 is a block diagram for explaining a method of measuring desired wave reception power versus interference wave reception power + noise power in the communication terminal apparatus.

FIG. 5 is a diagram for explaining a method of measuring a desired wave reception power / interference wave reception power + noise power ratio of the communication terminal apparatus.

FIG. 6 is a data frame configuration diagram used in communication using the base station apparatus of the present invention.

FIG. 7 is a diagram illustrating a data frame configuration used in communication using the base station apparatus of the present invention.

FIG. 8 is a sequence diagram between a base station device and a communication terminal device according to the present invention.

FIG. 9 is a sequence diagram between a base station device and a communication terminal device according to the present invention.

FIG. 10 is a sequence diagram between a base station device and a communication terminal device according to the present invention.

FIG. 11 is a sequence diagram between a base station device and a communication terminal device according to the present invention.

FIG. 12 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 13 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 14 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 15 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 16 is a block diagram showing a configuration of a base station apparatus according to Embodiment 2 of the present invention.

FIG. 17 is a block diagram showing a configuration of a communication terminal apparatus that performs wireless communication with the base station apparatus according to the above-described embodiment.

FIG. 18 is a block diagram for explaining a method of measuring a desired wave reception power in the communication terminal apparatus.

FIG. 19 is a block diagram for explaining a method of measuring desired wave reception power / interference wave reception power + noise power in the communication terminal apparatus.

FIG. 20 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 21 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 22 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 23 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 24 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 25 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 26 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 27 is a flowchart for explaining a transmission rate switching method in the base station apparatus according to the above-mentioned embodiment.

FIG. 28 is a diagram for explaining transmission rate control between layers in the base station apparatus of the present invention.

FIG. 29 is a flowchart for explaining transmission rate control between layers in the base station apparatus of the present invention.

[Explanation of symbols]

 101, 201 Antenna 102, 202 Antenna Duplexer 103, 203 RF Reception Circuit 104, 204 Demodulation Circuit 105 Separation Circuit 106 Transmission Rate Switching Control Circuit 107 Transmission Frame Creation Circuit 108, 207 Modulation Circuit 109, 208 Transmission RF Circuit 205 SIR Measurement Circuit 206 Multiplexing circuit 301, 401 Complex multiplying circuit 302, 402 Complex conjugate circuit 303 Power measuring circuit 403 Desired power measuring circuit 404 Interference power + noise power measuring circuit 405 Ratio calculating circuit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Osamu Kato 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa F-term in Matsushita Communication Industrial Co., Ltd. 5K067 AA02 AA33 BB04 DD42 DD45 EE02 EE10 KK13

Claims (7)

[Claims] 1. An average transmission power calculating means for calculating an average value of transmission power, a comparing means for comparing the average value of the transmission power with a predetermined allowable transmission power value, and a transmission rate according to a comparison result of the comparing means. And a transmission rate control means for changing the transmission rate. 2. A radio transmission unit, a radio reception unit, a transmission power control unit for increasing or decreasing transmission power of the radio transmission unit according to transmission power control information received by the radio reception unit, and a transmission power of the radio transmission unit. Average transmission power calculation means for calculating an average value of the transmission power, permissible transmission power holding means for holding a predetermined permissible transmission power value, comparison means for comparing the average value of the transmission power and the permissible transmission power value, A transmission rate control unit for changing a transmission rate according to a comparison result of the comparison unit. 3. The transmission rate control unit according to claim 1, wherein the transmission rate control unit controls a transmission rate according to an average value of transmission power measured in units of at least one frame. Wireless communication device. 4. The radio communication apparatus according to claim 1, wherein said transmission rate control means controls a transmission rate by changing a spreading factor. 5. The wireless communication apparatus according to claim 1, wherein the allowable transmission power value of the allowable transmission power holding unit is set by a control unit located in an upper layer. . 6. The transmission rate control unit according to claim 1, wherein the transmission rate control unit decreases the transmission rate when the comparison result of the comparison unit indicates that the average value has reached an allowable transmission power value. The wireless communication device according to claim 5. 7. A transmission rate control method usable for a radio communication device having a radio transmission unit and a radio reception unit, wherein the transmission power control information is received by the radio reception unit; Increasing and decreasing the transmission power of the wireless transmission means in accordance with, calculating an average value of the transmission power of the wireless transmission means, comparing the average value with a predetermined allowable transmission power value, Changing the transmission rate according to the comparison result.