JP2003244069A - Transmission power control apparatus and transmission power control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease multi-path interference by a common channel so as to suppress deterioration in a reception characteristic. <P>SOLUTION: A transmission power control discrimination section 112 discriminates whether or not transmission power is a prescribed value or below on the basis of an instruction outputted from a TPC bit discrimination section 111 and outputs an instruction of transmission of power of a prescribed value to a transmission power value decision section 113 when the transmission power is the prescribed value or below. When the transmission power value decision section 113 receives an output of the instruction of power at the prescribed value from the transmission power control discrimination section 112, the transmission power value decision section 113 controls a transmission wireless section 104 to transmit the power at the prescribed value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transmission power control apparatus and a transmission power control method suitable for use in a base station apparatus and a communication terminal apparatus of a mobile communication system.

[0002]

2. Description of the Related Art Conventionally, as a transmission power control device, one disclosed in, for example, Japanese Patent Laid-Open No. 2001-7759 is known. In this transmission power control device, the reception side measures the reception quality, compares the measured reception quality with the target reception quality, and if the measured reception quality is larger than the target reception quality, decreases the transmission power. Request signal (transmission power control bit: TPC (Transmit)
If the measured reception quality is smaller than the target reception quality, a signal (TPC bit) requesting to increase the transmission power is transmitted to the transmission side. The sender is the TPC sent from the receiver
The transmission power is controlled according to the bit.

FIG. 9 is a flow chart for explaining the conventional transmission power control on the transmitting side. First, the signal transmitted from the receiving side is received, the received signal is despread, demodulated using the despread signal obtained by despreading, and decoded using the demodulated signal to obtain the TPC bit. In ST901, it is determined whether the TPC bit is “instruction to increase transmission power”. When the TPC bit is “instruction to increase transmission power”, in ST902, the transmission power value of the dedicated channel on the transmission side is set to a certain level (for example, 1).
dB) and the TPC bit is “instruction to decrease transmission power”, in ST905, the transmission power value of the dedicated channel on the transmission side is set to a certain level (for example, 1d).
B) Decrease the transmission power value to determine the transmission power value (ST903), and transmit with the transmission power value after control (ST904).

[0004]

However, in the conventional transmission power control, when a request to reduce the transmission power continues, the transmission side reduces the transmission power of the dedicated channel in response to the request, so that the transmission power is kept constant. The transmission power of the dedicated channel becomes very small relative to the common channel that is transmitting. Therefore, on the receiving side, multipath interference due to the common channel with respect to the dedicated channel increases, and there is a problem that the reception characteristic of the dedicated channel may be significantly deteriorated.

The present invention has been made in view of the above circumstances, and provides a transmission power control apparatus and a transmission power control method capable of suppressing deterioration of reception characteristics of an individual channel caused by multipath interference due to a common channel. With the goal.

[0006]

A transmission power control apparatus according to the present invention comprises a transmission power value determining means for determining a transmission power value based on a transmission power control signal, a determination result of the transmission power value determining means, and a predetermined result. And a transmission power control unit that sets a transmission power value to the predetermined value when the determination result is less than or equal to the predetermined value.

Further, the transmission power control means is based on the transmission power control signal when the transmission power control signal is a request to increase the transmission power after the determination result of the transmission power value determination means becomes equal to or less than a predetermined value. The transmission power value is determined by the transmission power control.

According to these configurations, by not lowering the transmission power value of the dedicated channel to a predetermined value or less, it is possible to reduce multipath interference due to the common channel and suppress deterioration of reception characteristics.

Further, the transmission power control means is a request transmission power control signal for further reducing the transmission power a predetermined number of times within a predetermined period after the determination result of the transmission power value determining means becomes equal to or less than a predetermined value. When it receives, the transmission power value is set to the predetermined value.

According to this structure, even if the transmission power value becomes equal to or less than the predetermined value, the transmission power value is not immediately changed to the predetermined value. As a result, the state of the propagation path is accurately tracked, so that it is possible to maintain more accurate transmission power control, reduce multipath interference due to the common channel, and suppress deterioration of reception characteristics.

Further, the transmission power control means has a predetermined value
The configuration is determined from the ratio of the transmission power of the dedicated channel and the transmission power of the common channel.

According to this configuration, the predetermined value can be determined from the deterioration of the allowable reception characteristic from the reception characteristic caused by the multipath interference of the common channel with respect to the individual channel, which is known in advance. As a result, the predetermined value can be obtained more accurately, so that the deterioration of the reception characteristic can be suppressed to the minimum.

Further, the transmission power control means is
The configuration is determined from the amount of interference given to other cells.

According to this structure, the predetermined value can be determined from the transmission power that is the amount of interference with other cells that can be tolerated. As a result, since the predetermined value can be obtained more accurately, it is possible to suppress the deterioration of reception characteristics by suppressing the amount of interference with other cells due to excessive transmission power.

The predetermined value is a value determined from the ratio of the transmission power of the dedicated channel and the transmission power of the common channel,
The smaller value of the values determined from the amount of interference given to other cells is adopted.

According to this configuration, the predetermined value is determined from the deterioration of the reception characteristic that is allowable, from the reception characteristic caused by the multipath interference of the common channel with respect to the dedicated channel, which is known in advance. Also, a predetermined value is determined from the transmission power that is an allowable amount of interference with other cells. As a result, it is possible to suppress multipath interference and the amount of interference with other cells, and at the same time increase the subscriber capacity of the mobile communication system.

Further, the transmission power control apparatus of the present invention comprises a reception quality measuring means for measuring the reception quality of a received signal, and a target reception quality for controlling the target reception quality based on the reception quality measured by the reception quality measuring means. A configuration is provided that includes a control unit and a reception quality comparison unit that compares the reception quality measured by the reception quality measurement unit with the target reception quality.

Further, the target reception quality control means adopts a configuration in which the target reception quality is increased when the reception quality measured by the reception quality measuring means becomes equal to or higher than the first threshold value.

According to these configurations, by changing the target reception quality to a large value, the receiving side reduces the number of requests for reducing the transmission power, so that the transmission power of the dedicated channel on the transmission side is reduced. Can be prevented. As a result, it is possible to reduce multipath interference due to the common channel and suppress deterioration of reception characteristics.

Further, the target reception quality control means, after increasing the target reception quality, and before increasing the target reception quality when the reception quality measured by the reception quality measuring means becomes less than or equal to the second threshold value. Adopt a configuration that returns to the original value.

According to this configuration, after changing the target reception quality to a large value, when the measured reception quality becomes small, the target reception quality is returned to the original value before the increase.
Prevents transmission with extra power. As a result, interference with other cells can be suppressed.

Further, the target reception quality control means, after the reception quality measured by the reception quality measuring means becomes equal to or higher than the first threshold value, further exceeds the first threshold value a predetermined number of times within a predetermined period. In that case, a configuration is adopted in which the target reception quality is increased.

The target reception quality control means further increases the target reception quality, and after the reception quality measured by the reception quality measuring means becomes equal to or less than the second threshold value, the target reception quality control means further sets a predetermined period. When the number of times becomes equal to or less than the second threshold, the configuration is returned to the original value before increasing the target reception quality.

According to these configurations, the target reception quality is not immediately changed even if the measured reception quality value becomes equal to or more than the predetermined threshold value or less than the threshold value. As a result, the state of the propagation path is accurately tracked, so that it is possible to maintain more accurate transmission power control, reduce multipath interference due to the common channel, and suppress deterioration of reception characteristics.

The base station apparatus of the present invention has a configuration including any one of the above transmission power control apparatuses. The communication terminal apparatus of the present invention has a configuration including any one of the above transmission power control apparatuses.

With these configurations, it is possible to reduce the multipath interference due to the common channel and suppress the deterioration of the reception characteristic by not lowering the transmission power value of the dedicated channel to a predetermined value or less.

The transmission power control method of the present invention comprises a step of determining a transmission power value based on a transmission power control signal, and a step of comparing the determined transmission power value with a predetermined value. When the determined transmission power value is less than or equal to the predetermined value, the predetermined value is used as the transmission power value.

The transmission power control method of the present invention comprises the steps of measuring the reception quality of the received signal, controlling the target reception quality based on the measured reception quality, the measured reception quality and the target reception quality. And a step of increasing the target reception quality when the measured reception quality exceeds a predetermined value.

By these methods, the transmission power value of the dedicated channel is not lowered below a predetermined value, so that the multipath interference due to the common channel can be reduced and the deterioration of the reception characteristic can be suppressed.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is that, when the transmission power on the transmission side becomes a predetermined value or less, by transmitting an individual channel with a transmission power value of a predetermined value, a common channel for the individual channel is transmitted. This is to reduce the multipath interference due to and to reduce the deterioration of the dedicated channel reception characteristics.

Further, the essence of the present invention is that, when the reception quality measured on the reception side exceeds a predetermined value, the target reception quality is changed to a large value so that the transmission from the reception side to the transmission side on the transmission side is performed. By reducing the number of requests to reduce the power and preventing the transmission power of the dedicated channel on the transmission side from becoming extremely small, multipath interference due to the common channel on the dedicated channel is reduced and deterioration of reception characteristics on the reception side is prevented. It is to reduce.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (Embodiment 1) FIG.1 is a block diagram showing a configuration of a radio communication apparatus equipped with a transmission power control apparatus according to Embodiment 1 of the present invention. The transmission power control device shown in this figure is
It can be used for a base station device or a communication terminal device of a mobile communication system.

In FIG. 1, a transmission frame creating section 101
Creates a transmission frame from the transmission data and outputs the created transmission frame to the modulator 102. The modulation unit 102 modulates the created transmission frame to generate a modulation signal, the spreading unit 103 performs a spreading process on the modulation signal, and the transmission wireless unit 104 transmits data output from a transmission power value determining unit 113 described below. In accordance with the power control signal, the spread signal is amplified to a predetermined level of power and output.
05 outputs the wirelessly amplified signal to the antenna 106,
The antenna 106 transmits a wireless signal to a communication partner.

The antenna 106 receives the radio wave transmitted from the communication partner, the antenna sharing unit 105 outputs the received radio signal to the reception radio unit 107, and the reception radio unit 10 receives the radio signal.
Reference numeral 7 performs a predetermined radio processing on the received radio signal, despreading section 108 performs despreading processing on the radio processed signal, demodulation section 109 demodulates the signal after the despreading processing, and decoding section 11
0 decodes the demodulated signal and outputs the TPC bit to the TPC bit determination unit 111.

The TPC bit determination unit 111 is the decoding unit 11
With reference to the TPC bit output from 0, the transmission power control determination unit 112 is instructed as to whether it is a request to increase transmission power or a request to decrease transmission power. Transmission power control determination unit 1
12 sets the transmission power value to a predetermined value based on the instruction output from the TPC bit determination unit 111, or T
The transmission power value determining unit 113 is instructed whether or not the value from the PC bit determining unit 111 is reflected. The transmission power value determination unit 113 determines the transmission power value according to the instructions from the TPC bit determination unit 111 and the transmission power control determination unit 112, and outputs it to the transmission wireless unit 104. Further, as will be described later, the threshold calculation unit 114 determines the threshold from the ratio of the transmission power of the dedicated channel and the common channel or the amount of interference that the transmission power gives to other cells, and sends the determined threshold to the transmission power control determination unit 112. Output.

Next, the operation of the transmission power control apparatus according to this embodiment will be described using the flow chart of FIG.

In ST1, the transmission power control determination section 11
2 compares the transmission power value at the time of the previous transmission power control (hereinafter, referred to as “previous transmission power value”) with the threshold value A.

As a result of comparison, if the previous transmission power value is larger than the threshold value A, the transmission power control determination unit 112 determines the transmission power value so as to control the transmission power value based on the instruction output from the TPC bit determination unit 111. Instructing unit 113 (ST3), transmission power value determining unit 113, based on the instructions from TPC bit determining unit 111 and transmission power control determining unit 112, requests an increase in transmission power,
If the transmission power value after increasing the transmission power value by a predetermined level (ST5) is instructed to be reduced, if the transmission power value after decreasing by the predetermined level (ST6) is not larger than the threshold value A, the threshold value A When it is larger than the threshold value A, the transmission power value after the reduction is output to the transmission radio section 104 (ST
7).

As a result of the comparison, if the previous transmission power value is less than or equal to the threshold value A, in ST2, the transmission power control determination unit 112
Refers to the instruction output from the TPC bit determination unit 111, and in the case of an instruction requesting an increase in transmission power, TPC
The transmission power value determination unit 113 is instructed to control the transmission power value based on the instruction output from the bit determination unit 111, and the transmission power value determination unit 113 causes the TPC bit determination unit 1
11 and an instruction from the transmission power control determination unit 112, the transmission power value is increased by a predetermined level (ST5), and the resulting transmission power value is output to the transmission wireless unit 104 (ST8). On the other hand, as a result of referring to the instruction output from the TPC bit determination unit 111, if the instruction is a request to reduce the transmission power, the transmission power control determination unit 112 determines the transmission power value to be an instruction to set the threshold A as the transmission power value. The transmission power value determining unit 113 outputs the transmission power value to the unit 113.
According to the instruction from 2, the transmission power value is set to the threshold value A (ST
4), and the resulting transmission power value is the transmission radio unit 104.
To (ST8).

For example, the transmission power of the dedicated channel at a certain time is 21 dBm, and the predetermined threshold A of the transmission power is 20.
When it is set to 5 dBm and the range of increase / decrease in transmission power is 1 dB, when there is a request to decrease the next transmission power from the TPC bit, the transmission power becomes 20 dBm and the threshold A (20.5
dBm). Therefore, an instruction to transmit with the threshold value A (20.5 dBm) instead of controlling the transmission power according to the TPC bit is output from the transmission power control determination unit 112 to the transmission power value determination unit 113.

At the next point in time, and even if there is a request to reduce the next transmission power from the TPC bit, the transmission power control determination unit 112 issues an instruction to transmit at the threshold A to the transmission power value determination unit 1.
13 and the power continues to be transmitted at threshold A unless there is a request from the TPC bit to increase the next transmit power.

As described above, according to the present embodiment, it is possible to prevent the ratio of the dedicated channel to the common channel from decreasing by not lowering the transmission power of the dedicated channel to a predetermined value or less, and the multi-channel by the common channel is suppressed. Path interference can be reduced and deterioration of reception characteristics can be suppressed.

After the transmission power control determination unit 112 determines that the transmission power value is less than or equal to the threshold value A, the transmission power value is not exceeded until a request is made to further reduce the transmission power a predetermined number of times within a predetermined period. It is also possible to determine that is not lowered below the threshold value A.

As an example, a case where the predetermined cycle is "5" and the predetermined number of times is "4" and the change over time of the transmission power value after the transmission power control is as shown in FIG. 3 will be described.

The threshold A is 20.5 dBm, the range of increase / decrease in transmission power is 1 dB, and the transmission power value is 21 dB at time t _i .
Assuming that m, the transmission power value is 20 when the instruction to reduce the transmission power is received by the TPC bit at time t _{i + 1} .
Only when the transmission power value becomes dBm, the transmission power control determination unit 112 determines that the transmission power value becomes equal to or less than the threshold value A. At this point, the transmission power value is equal to or less than the threshold value A and is still once and less than the predetermined number of four times, so 19 dBm is transmitted as the transmission power value. Hereinafter, when an instruction to continuously reduce the transmission power comes and an instruction to reduce the transmission power at the fourth time comes at t _{i + 4} , the transmission reaches the threshold value A because the predetermined number of times is reached within the predetermined period.

The flow chart of the above operation is shown in FIG. In ST1, if the transmission power value is equal to or less than the threshold value A, in ST11, the transmission power control determination unit 112 sets T
In the case of an instruction to request an increase in transmission power by referring to the instruction output from the PC bit determination unit 111, the transmission power value is controlled so as to control the transmission power value based on the instruction output from the TPC bit determination unit 111. Instruct the decision unit 113,
In ST15, the transmission power value determination unit 113 causes the TPC
Based on an instruction from the bit determination unit 111 and the transmission power control determination unit 112, the transmission power value is increased by a predetermined level, and the resulting transmission power value is output to the transmission wireless unit 104. On the other hand, as a result of referring to the instruction output from the TPC bit determination unit 111, in the case of an instruction requesting a decrease in transmission power, in ST12, a predetermined period has elapsed after the transmission power value became equal to or less than the threshold value A. Determine whether or not. If the predetermined period has passed, in ST15,
The transmission power value is reduced by a predetermined level, and in ST16, the resulting transmission power value is output to transmission radio section 104. If the predetermined period has not elapsed in ST12, it is determined in ST13 whether or not the number of times that the transmission power value becomes equal to or less than the threshold value A is the predetermined number of times or more. If the transmission power value is not equal to or less than the predetermined number of times threshold value A, ST1
5, the transmission power value is reduced by a predetermined level, and ST
At 16, the transmission wireless unit 104 transmits with the transmission power value acquired from the transmission power control determination unit 112. ST13
In the case where the transmission power value is equal to or smaller than the threshold value A for a predetermined number of times,
In ST14, the transmission power value is set to the threshold value A, and ST1
At 6, the resulting transmission power value is output to the transmission wireless unit 104.

That is, until the transmission power value becomes equal to or lower than the threshold value A and does not reach the predetermined number of times, transmission is performed with the transmission power after a predetermined level reduction as instructed by the TPC bit, and the threshold value A is not reached until the predetermined number of times is reached. It transmits with the transmission power of.

As a result, it becomes possible to accurately follow the state of the propagation path, maintain more accurate transmission power control, reduce multipath interference due to common channels, and suppress deterioration of reception characteristics.

The threshold value A can be determined from the ratio of the transmission power of the dedicated channel and the transmission power of the common channel.

FIG. 5A is a block diagram showing the configuration of the threshold value calculation unit 114 when the threshold value A is obtained from the ratio of the transmission powers of the dedicated channel and the common channel. The transmission power ratio versus error rate characteristic measuring section 501 calculates in advance the error rate characteristic with respect to the transmission power ratio of the dedicated channel and the common channel on the receiving side as shown in FIG. 5B. R ₀ calculation unit 502
Calculates the minimum value R ₀ of the transmission power ratio that satisfies the desired error rate P ₀ shown in FIG. 5B from the error rate characteristics with respect to the transmission power ratio of the dedicated channel and the common channel. The dedicated channel transmission power calculation unit 503 uses the transmission power of the common channel and R ₀ that are known values from the notification from the communication system and the like, (transmission power of dedicated channel) = R ₀ × (transmission power of common channel) ) Calculates the transmission power of the dedicated channel that satisfies the desired error rate. The transmission power of this dedicated channel becomes the threshold A.

This threshold value calculation unit 114 may be installed in the transmission power control apparatus of the base station apparatus or the communication terminal apparatus, or the threshold value A calculated in advance by computer simulation or the like is set in the transmission power control apparatus. You may.

As a result, in advance,
Deterioration of the reception characteristics can be minimized by determining a predetermined value from the deterioration of the reception characteristics that is allowable based on the reception characteristics caused by multipath interference on the dedicated channel due to the common channel.

The threshold value A can be determined from the amount of interference that transmission power gives to other cells.

FIG. 6A is a block diagram showing the configuration of the threshold value calculation unit 114 when the threshold value A is obtained from the interference of other cells. The other cell interference-to-error rate characteristic measuring section 601 is configured in advance in FIG.
An error rate characteristic with respect to the amount of interference given to other cells on the receiving side as shown in (b) is calculated. I ₀ calculator 602
Calculates the minimum value I ₀ of the interference amount given to the other cell satisfying the desired error rate P ₀ from the error rate characteristic with respect to the interference amount given to the other cell. Dedicated channel transmission power calculation unit 603
Calculates the transmission power of the dedicated channel at this time from I ₀ . The transmission power of this dedicated channel becomes the threshold A.

This threshold value calculation unit 114 may be installed in the transmission power control apparatus of the base station apparatus or the communication terminal apparatus, or the threshold value A calculated in advance by computer simulation or the like is set in the transmission power control apparatus. You may.

Thus, by determining a predetermined value from the transmission power that gives an allowable amount of interference to other cells, it is possible to suppress the amount of interference to other cells due to excessive transmission power.

The smaller value of the value obtained from the ratio of the transmission power of the dedicated channel and the common channel and the value obtained from the amount of interference of the transmission power to other cells may be used as the threshold value A.

As a result, in advance,
From the reception characteristics caused by multipath interference on the dedicated channel due to the common channel, the predetermined value is determined from the deterioration of the reception characteristics that can be tolerated, and the predetermined value is determined from the transmission power that is the amount of interference to other cells that is tolerable By that,
It is possible to suppress multipath interference and the amount of interference with other cells, and at the same time increase the subscriber capacity of the mobile communication system.

(Embodiment 2) FIG. 7 is a block diagram showing the configuration of a radio communication apparatus equipped with a transmission power control apparatus according to Embodiment 2 of the present invention. The wireless communication device shown in this figure can be used for a base station device and a communication terminal device of a mobile communication system.

In FIG. 7, an antenna 701 captures and receives a radio wave transmitted from a communication partner, an antenna sharing unit 702 transmits the received radio signal to a reception radio unit 703, and a reception radio unit 703, The received wireless signal is subjected to predetermined wireless processing, the despreading unit 704 performs despreading processing on the wireless processed signal, the demodulation unit 705 demodulates the despread signal, and the decoding unit 706 At the same time as decoding the demodulated signal and outputting the received data, the reception quality measuring unit 711 measures the reception quality of the received wireless signal.

The target reception quality control section 712 determines whether the reception quality measured by the reception quality measuring section 711 is equal to or higher than the threshold value B. If the reception quality is equal to or higher than the threshold value B, an instruction to change the target reception quality to a large value is received. It is output to the comparison unit 713.

Further, the target reception quality control section 712 determines whether the reception quality measured by the reception quality measuring section 711 is equal to or lower than the threshold value C after changing the target reception quality value to a large value. An instruction to restore the original value before increasing the reception quality is output to the reception quality comparison unit 713.

The reception quality comparing section 713 compares the reception quality measured by the reception quality measuring section 711 and the target reception quality control section 7 with each other.
If there is an instruction to change the target reception quality from 12, the target reception quality after the change is compared with the target reception quality up to that point if there is no instruction to change the target reception quality from the target reception quality control unit 712, and comparison is made. The result is the TPC bit creation unit 71
Output to 4.

Based on the comparison result from the target reception quality control section 712, the TPC bit creation section 714 creates the TPC bit as a request to increase or decrease the transmission power of the communication partner, and the transmission frame creation section 707
Output to.

The transmission frame creation section 707 creates a transmission frame from the transmission data and the TPC bit, and the modulation section 7
08 modulates the created transmission frame to generate a modulation signal, a spreading unit 709 performs a spreading process on the modulation signal, and a transmission wireless unit 710 amplifies the spread signal to a predetermined level of power. The antenna common part 702,
The wirelessly amplified signal is transmitted to the antenna 701, and the antenna 701 transmits the wireless signal to the communication partner.

Next, the operation of the transmission power control apparatus according to this embodiment will be described using the flow chart of FIG.

If the target reception quality has not been changed to a small value in ST21, the target reception quality control section 712 determines in ST22 whether the reception quality (measured reception quality) measured by the reception quality measuring section 711 is equal to or more than the threshold value B. judge. If the determination result is equal to or greater than the threshold value B, in ST24, an instruction to change the target reception quality to a large value is output to the reception quality comparison unit 713, and the reception quality comparison unit 713 changes the target reception quality to a large value. After that, in ST26, the reception quality comparison unit 713 compares the measured reception quality with the target reception quality, and S
The TPC bit is created at T27.

If the target reception quality is a large value in ST21, the target reception quality control section 71 is operated in ST23.
2 determines whether the reception quality (measured reception quality) measured by the reception quality measuring unit 711 is larger than the threshold value C. When the determination result is less than or equal to the threshold value C, in ST25, the reception quality comparison unit 7 issues an instruction to restore the original value before the target reception quality is increased.
13, and the reception quality comparison unit 713 restores the original value before increasing the target reception quality. After that, in ST26, reception quality comparison section 713 compares the measured reception quality with the target reception quality, and creates a TPC bit in ST27.

For example, the threshold B is 12 dB and the threshold C is 5 d.
B, the original target reception quality is 7 dB, the changed target reception quality is 9 dB, and the measured reception quality is 15 dB, it is determined that the measured reception quality is equal to or higher than the threshold B (12 dB), and the target reception quality is It is changed to 9 dB. Therefore,
The changed target reception quality (9 dB) is compared with the measured reception quality (15 dB). Here, since the measured reception quality is higher, the request to reduce the transmission power of the base station is output as the TPC bit.

Here, the original target reception quality (7d
In the state of B), unless the communication partner reduces the transmission power value of the dedicated channel by 8 dB, the reception quality does not approach the target reception quality, so that multipath interference due to the common channel causes deterioration of reception characteristics. On the other hand, in the case of the changed target reception quality (9 dB), the reception quality can approach the target reception quality only by the communication partner reducing the transmission power value of the dedicated channel by 6 dB.

On the other hand, if the measured reception quality becomes 3 dB after changing the target reception quality to 9 dB, it is determined that the measured reception quality is less than or equal to the threshold value C (5 dB), and the target reception quality is the original value ( 7 dB). Therefore, the changed target reception quality (7 dB) and the measured reception quality (3
dB) is compared. Since the target reception quality is higher here, the request to increase the transmission power of the communication partner is output as the TPC bit.

If the target reception quality remains large (9 dB), the reception quality cannot approach the target reception quality unless the communication partner increases the transmission power value of the dedicated channel by 6 dB.
Interference with other cells will increase. On the other hand,
When the target reception quality is returned to the original value, the reception quality can approach the target reception quality only by the communication partner increasing the transmission power value of the dedicated channel by 4 dB.

The comparison result indicates that the TPC bit creating section 714 requests T as a request to increase or decrease the transmission power of the communication partner.
Converted into PC bits, and the TPC bits are output to the transmission frame creation unit 707.

The transmission data and TPC bits are created as a transmission frame by the transmission frame creation unit 707, the transmission frame is modulated by the modulation unit 708, and the modulated signal generated by the modulation is spread by the spreading unit 709. The spread signal is amplified by the transmission radio section 710 to a predetermined level of power, and the radio-amplified signal is transmitted from the antenna 701 to the communication partner via the antenna sharing section 702.

As described above, according to the present embodiment, when the measured reception quality is high, the communication partner is requested to keep decreasing the transmission power, and the communication partner reduces the transmission power of the dedicated channel, and the common channel is reduced. In contrast to the problem that multipath interference causes deterioration of reception characteristics, by changing the target reception quality to a large value, the number of requests to reduce the transmission power is reduced and the transmission power of the dedicated channel of the communication partner is reduced. Since it becomes larger, multipath interference due to the common channel becomes smaller, and deterioration of reception characteristics can be suppressed.

Further, according to the present embodiment, after the target reception quality is changed to a large value, when the measured reception quality becomes small, the target reception quality is returned to the original value before the increase, so It is possible to suppress interference with other cells due to transmission with high power.

After the target reception quality control unit 712 determines that the target reception quality should be changed to a large value, the target reception quality is changed only when the threshold value B is equal to or more than a predetermined number of times within a predetermined period. It can also be determined.

Further, after the target reception quality control section 712 determines that the target reception quality is returned to the original value, the target reception quality is changed only when the threshold value C becomes equal to or less than the predetermined number of times within a predetermined period. Then, it can be determined.

This makes it possible to more accurately follow the state of the propagation path, maintain more accurate transmission power control, reduce multipath interference due to the common channel, and suppress deterioration of reception characteristics. .

The target reception quality of this embodiment is
For example, signal power to interference power ratio (SIR) and carrier power to interference power ratio (CIR).

The present invention is not limited to the above-described first and second embodiments, but can be implemented with various modifications. For example, the first and second embodiments may be combined and used.

[0082]

As described above, according to the present invention,
It is possible to reduce multipath interference due to the common channel and suppress deterioration of the reception characteristics of the dedicated channel. Also,
It is possible to suppress interference with other cells due to transmission with extra power.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless communication device equipped with a transmission power control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the transmission power control apparatus according to the above embodiment.

FIG. 3 is a diagram showing a time transition example of a transmission power value by the transmission power control device according to the above embodiment.

FIG. 4 is a flowchart showing the operation of the transmission power control apparatus according to the above embodiment.

FIG. 5 is a block diagram showing a configuration of a transmission power control apparatus threshold value calculation unit according to the above embodiment and a diagram showing an error rate characteristic of a transmission power ratio of an individual channel and a common channel.

FIG. 6 is a block diagram showing a configuration of a threshold value calculation unit of the transmission power control apparatus according to the above embodiment and a diagram showing an error rate characteristic of an interference amount given to another cell.

FIG. 7 is a block diagram showing a configuration of a wireless communication device equipped with a transmission power control device according to a second embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the transmission power control apparatus according to the above embodiment.

FIG. 9 is a flowchart for explaining conventional transmission power control.

[Explanation of symbols]

104, 710 Transmission wireless unit 107, 703 Reception wireless unit 108, 704 despreading unit 109, 705 Demodulator 110,706 Decoding unit 111 TPC bit determination unit 112 Transmission power control determination unit 113 transmission power value determination unit 114 threshold calculator 711 Reception quality measurement unit 712 Target reception quality control unit 713 Reception quality comparison unit 714 TPC bit creation section

Claims (14)

[Claims] 1. A transmission power value determining means for determining a transmission power value based on a transmission power control signal, a comparing means for comparing a determination result of the transmission power value determining means with a predetermined value, and the determination result. And a transmission power control unit that sets a transmission power value to the predetermined value when the transmission power value is equal to or less than the predetermined value. 2. The transmission power control means is based on the transmission power control signal when the transmission power control signal is a request to increase the transmission power after the determination result of the transmission power value determination means becomes equal to or less than a predetermined value. The transmission power control apparatus according to claim 1, wherein the transmission power control is performed according to the transmission power value determined by the above. 3. A transmission power control signal for requesting that the transmission power control means further reduce the transmission power a predetermined number of times within a predetermined period after the determination result of the transmission power value determining means becomes equal to or less than a predetermined value. 3. The transmission power control device according to claim 1, wherein the transmission power value is set to the predetermined value when is received. 4. The predetermined value is determined from the ratio of the transmission power of the dedicated channel and the transmission power of the common channel, or the amount of interference given to other cells, according to any one of claims 1 to 3. The transmission power control device according to. 5. The predetermined value is a value determined from the ratio of the transmission power of the dedicated channel and the transmission power of the common channel, or a value determined from the amount of interference given to other cells, whichever is smaller. The transmission power control device according to any one of claims 1 to 4. 6. A reception quality measuring means for measuring the reception quality of a received signal, a target reception quality controlling means for controlling a target reception quality based on the reception quality measured by the reception quality measuring means, and the reception quality measuring means. And a reception quality comparison means for comparing the reception quality measured by the target reception quality with the reception quality measured by the transmission power control device. 7. The target reception quality control means increases the target reception quality when the reception quality measured by the reception quality measuring means is equal to or higher than a first threshold value. Transmission power control device. 8. The target reception quality control means increases the target reception quality after increasing the target reception quality and when the reception quality measured by the reception quality measuring means is equal to or lower than a second threshold value. 8. The transmission power control device according to claim 6 or 7, wherein the transmission power control device returns to the previous original value. 9. The target reception quality control means, after the reception quality measured by the reception quality measuring means becomes equal to or higher than a first threshold value, further exceeds a first threshold value a predetermined number of times within a predetermined period. 7. The transmission power control device according to claim 6, wherein the target reception quality is increased when the transmission power becomes low. 10. The target reception quality control means further increases the target reception quality, and further within a predetermined period after the reception quality measured by the reception quality measurement means becomes equal to or less than a second threshold value. 7. The transmission power control apparatus according to claim 6, wherein the target reception quality is returned to the original value before the target reception quality is increased when the value becomes equal to or less than the second threshold value a predetermined number of times. 11. A base station apparatus comprising the transmission power control apparatus according to any one of claims 1 to 10. 12. A communication terminal apparatus comprising the transmission power control apparatus according to claim 1. Description: 13. A method comprising: determining a transmission power value based on a transmission power control signal; and comparing the determined transmission power value with a predetermined value, wherein the determined transmission power value is A transmission power control method, wherein the predetermined value is used as a transmission power value when the value is equal to or less than the predetermined value. 14. A method comprising: measuring reception quality of a received signal; controlling a target reception quality based on the measured reception quality; and comparing the measured reception quality with the target reception quality. Then, the target reception quality is increased when the measured reception quality exceeds a predetermined value.