JP3014308B2 - Transmission power control method in mobile communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a transmission power control method in a mobile communication system.

[0002]

2. Description of the Related Art Conventionally, in wireless communication, transmission power control for suppressing transmission power is performed. By performing this transmission power control, effects such as saving power consumption and reducing interference with other wireless channels can be obtained. In particular, C
DMA (Code Division Multipl)
In the e Access (code access multiple access) system, since suppressing the amount of interference as low as possible directly leads to an increase in subscriber capacity, transmission power control is an essential technology. In the CDMA system, the reception CI at the base station is
The transmission power of the mobile station is controlled so that R becomes equal to the target CIR, and the reception CIR (carrier interference ratio) at the mobile station is controlled.
Conventionally, a transmission power control method of controlling the transmission power of a base station so that is equal to a target CIR has been proposed.

FIG. 1 or 2 shows an example of a mobile station transmission power control method. In the configuration of FIG. 1, according to the timing chart shown in FIG.
When the transmission power is lower than the IR, a transmission power control signal “1” is sent to the mobile station 101 to increase the transmission power of the mobile station 101.
The mobile station 101 that has received the transmission power control signal “1” increases the transmission power by, for example, 1 dB. Conversely, when the received CIR at the base station 103 exceeds the target CIR, the mobile station 101
A transmission power control signal “0” is sent to the mobile station 101 to reduce the transmission power of the mobile station 101. The mobile station 101 that has received the transmission power control signal “0” lowers the transmission power by, for example, 1 dB.

In reality, even if each received CIR is controlled to be equal to the target CIR, it is impossible to completely match the received CIR to the target CIR because of measurement errors and control delays. Fluctuates and has a control error.

[0005] In addition, the amount of fluctuation of the reception CIR depends on the fading pitch and the number of reception paths (in radio transmission, a plurality of delayed waves having different timings via different paths are generated.
In the A system, since the wideband transmission using the spreading code is performed, the plurality of waves can be separately received, and the reception characteristics are improved by combining them. In general, the number of passes increases in an area such as an urban area where there are many reflective objects. ). That is, due to the control delay, when the fading pitch is small, the transmission power control cannot catch up with the fading fluctuation, and the fluctuation amount of the CIR increases. Conversely, when the fading pitch is large, the transmission power control follows the fading fluctuation, so that the fluctuation amount of the CIR becomes small.
In addition, as the number of reception paths increases, the effect of fading fluctuation can be reduced by performing path combining, so that the fluctuation amount of CIR decreases.

The target CI in the conventional transmission power control method
As shown in FIG. 3, R has a margin so as to satisfy required communication quality even when the reception CIR fluctuates most, and is set in advance as a fixed value.

[0007]

However, in the conventional transmission power control method described above, when the amount of fluctuation of the received CIR is small, a margin is taken more than necessary.
The transmission power of the mobile station and the base station becomes unnecessarily large, so that wasteful transmission power is wasted and the amount of interference increases, resulting in a decrease in subscriber capacity.

In designing the system, the amount of fluctuation in the received CIR is measured or estimated in advance, and the target CIR is measured.
Therefore, there is a disadvantage that the amount of work at the time of system design increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and reduces transmission power at a mobile station and a base station as compared with a conventional system by suppressing transmission power to a necessary minimum.
It is another object of the present invention to provide a transmission power control method capable of increasing the subscriber capacity by reducing the amount of interference.

[0010] Another object of the present invention is to provide a transmission power control method capable of easily performing system design.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a transmission power control method in a mobile communication system including a base station and a mobile station, wherein the transmission power of each radio channel in one of the base station and the mobile station is provided. Is calculated by comparing the reception CIR (carrier interference ratio) of the radio line at the other of the base station and the mobile station with the target C
And controlling the target CIR for each of the radio lines in the other station based on the line quality of each of the radio lines in one of the base station and the mobile station. And a transmission power control method.

Further, according to the present invention, said one of said stations has a measuring means for measuring a line quality for each radio line, and said changing step sets the line quality measured by said measuring means to a required value or more. The target CIR is changed to a required minimum value.

Further, according to the present invention, said one of the stations has a measuring means for periodically measuring the distribution of the received CIR for each radio line, and said changing step comprises the step of changing the received CIR measured by said measuring means. The target CIR is changed based on the distribution of the target CIR.

In the present invention, the step of changing preferably changes the target CIR so that the probability that the received CIR becomes lower than a required CIR in a distribution of the received CIR measured by the measuring means is equal to or less than a predetermined value. It is characterized by.

Further, in the present invention, either of the stations has a measuring means for periodically measuring a BER (bit error rate) of each radio line, and the changing step is performed by the measuring means. The target CIR is changed based on a BER.

Further, in the present invention, the changing step increases the target CIR when the BER measured by the measuring means is smaller than a required BER, and the BER measured by the measuring means is larger than the required BER. It is characterized in that the target CIR is sometimes reduced.

Further, according to the present invention, either of the stations has a measuring means for periodically measuring the number of reception paths and a fading pitch for each radio line, and the changing step is performed by the measuring means. The target CIR is changed based on the number of reception paths and a fading pitch.

Further, in the present invention, the changing step estimates a distribution of reception CIR from the number of reception paths and a fading pitch measured by the measurement means, and the reception CIR is a required CIR in the estimated distribution of reception CIR. The target CI is set so that the probability of lowering becomes lower than a predetermined value.
R is changed.

Also, the present invention provides the above-mentioned target CIR and received CI.
R is characterized by being given by a target level and a reception level.

Further, the present invention relates to a transmission power control method in a mobile communication system including a base station and a mobile station,
The transmission power of each radio link in one of the base station and the mobile station is reduced by the difference between the reception CIR (carrier interference ratio) of the radio link in the other station of the base station and the mobile station and the target CIR. And based on the channel quality of each radio link in either the base station or the mobile station, the target CI of all the radio links in the other station.
Setting R for each of the other stations.

Further, according to the present invention, one of the stations has a measuring means for measuring the reception quality of each radio line, and the other station is provided with the other station based on the line quality measured by the measuring means. And learning means for learning an average line quality characteristic in the step (c), wherein the setting step is performed based on the average line quality characteristic learned by the learning means.
Is set.

Further, according to the present invention, said one of the stations has a measuring means for measuring a distribution of received CIR for each radio line,
The other station receives the received CIR measured by the measuring means.
Learning means for learning an average reception CIR distribution at the other station from the distribution of the other stations, and the setting step sets the target CIR based on the average reception CIR distribution learned by the learning means. It is characterized by the following.

Further, in the present invention, the setting step sets the target CIR such that the probability that the received CIR becomes lower than a required CIR in an average received CIR distribution learned by the learning means is equal to or less than a predetermined value. It is characterized by doing.

Further, according to the present invention, one of the stations has a measuring means for measuring a BER (bit error rate) for each radio line, and the other station has a measuring means for measuring a BER measured by the measuring means. There is provided learning means for learning an average BER in the other station, and the setting step sets the target CIR based on the average BER learned by the learning means.

Also, in the present invention, the setting step is a step in which an average BER learned by the learning means is required.
The target CIR is increased when the BER is smaller than the ER, and the target CIR is decreased when an average BER learned by the learning means is larger than a required BER.

According to the present invention, either one of the stations has measuring means for measuring the number of reception paths and a fading pitch for each radio line, and the other station has the number of reception paths measured by the measuring means. And learning means for learning the average number of reception paths and the average fading pitch in the other station from the fading pitch and the average number of reception paths and average learned by the learning means. Target C based on a typical fading pitch
It is characterized in that IR is set.

Further, in the present invention, the setting step estimates an average reception CIR distribution from an average number of reception paths and an average fading pitch learned by the learning means. The target CIR is set such that the probability that the received CIR becomes lower than the required CIR in a suitable received CIR distribution is equal to or less than a predetermined value.

Further, the present invention is characterized in that the other station is a base station and has estimating means for estimating a reception CIR distribution at the base station from data of buildings in an area covered by the base station. The step of setting is such that the received CIR is the required CIR in the received CIR distribution estimated by the estimating means.
The target C is set so that the probability of lowering becomes equal to or less than a predetermined value.
It is characterized in that IR is set.

Also, the present invention provides the above-mentioned target CIR and received CI.
R is characterized by being given by a target level and a reception level.

Further, the present invention relates to a base station communicating with a mobile station in a mobile communication system, wherein the transmission power of each radio channel in the mobile station is reduced by the reception CIR (carrier interference) of the radio channel in the base station. Means for controlling the difference between the wave ratio) and the target CIR, and changing the target CIR for each wireless line based on the line quality of each wireless line in either the base station or the mobile station. And a base station.

Furthermore, the present invention relates to a mobile station communicating with a base station in a mobile communication system, wherein the transmission power of each radio channel in the base station is reduced by the reception CIR (carrier interference) of the radio channel in the mobile station. Means for controlling the difference between the wave ratio) and the target CIR, and changing the target CIR for each wireless line based on the line quality of each wireless line in either the base station or the mobile station. And a mobile station.

Further, the present invention relates to a base station communicating with a mobile station in a mobile communication system, wherein the transmission power of each radio channel in the mobile station is reduced by the reception CIR (carrier interference) of the radio channel in the base station. (Wave ratio) and the target CIR, and based on the channel quality of each radio channel in one of the base station and the mobile station, based on the channel quality of all radio channels in the base station. Means for setting a target CIR for each base station.

Further, the present invention relates to a mobile station communicating with a base station in a mobile communication system, wherein the transmission power of each radio channel in the base station is reduced by the reception CIR (carrier interference) of the radio channel in the mobile station. (Wave ratio) and the target CIR, and based on the channel quality of each radio channel in either the base station or the mobile station, Means for setting a target CIR for each mobile station.

According to the transmission power control method of the present invention, a plurality of base stations connected to a communication network and a plurality of mobile stations connected to the base station via a radio line are provided. (Carrier interference ratio) or the reception level, and the reception CIR or the reception level of each base station in a wireless communication system that controls the transmission power so that the reception CIR or the reception level of the base station is equal to the target value. While maintaining the required communication quality,
In addition, since different target values are set so that the transmission power is minimized, the transmission power of the mobile station and the base station is reduced as compared with the conventional method, and the subscriber capacity is increased because the amount of interference decreases. Further, since the target reception CIR or reception level of each line is automatically set without manually setting the target reception CIR or reception level, the target reception CIR or reception level is set manually. It is not necessary to do so, and system design becomes easy.

In the transmission power control method of the present invention, when the bit error rate is measured, the communication quality (bit error rate) is fed back to change the target reception CIR or reception level. The communication quality can be kept constant. Further, when measuring the number of reception paths and the fading pitch, control with higher responsiveness is possible because the measurement time is short.

In the transmission power control method of the present invention, a target reception CIR or reception level can be set according to the propagation characteristics in the communication area of each base station and the movement characteristics of the mobile station. Although the effect of reducing the transmission power and the effect of increasing the subscriber capacity are reduced as compared with the case where the target reception CIR or reception level is set for each radio line, the target reception CIR or reception level is changed for each radio line. Control becomes unnecessary, and the control load is reduced. Further, even when a target reception CIR or reception level is set for each wireless channel, it can be used to determine an initial value of the target reception CIR or reception level.

In the transmission power control method of the present invention, a target reception CIR or reception level can be set according to the movement characteristics of each mobile station. Compared with the case where a target reception CIR or reception level is set for each radio line, the effect of reducing transmission power and the effect of increasing subscriber capacity are reduced.
Control for changing the target reception CIR or reception level for each radio line becomes unnecessary, and the control load is reduced. Further, even when a target reception CIR or reception level is set for each wireless channel, it can be used to determine an initial value of the target reception CIR or reception level.

Further, in the transmission power control method of the present invention, the control is performed such that the probability of falling below the required reception CIR or the reception level is not more than a certain value, so that the lower limit of the reception CIR or the reception level can be kept constant. .

Further, the transmission power control method of the present invention can keep the bit error rate constant.

Further, the transmission power control method of the present invention can provide the same effect even when either the reception level or the reception CIR is used as the target value. However, when the reception level is used as a reference, measurement becomes easy, but the reception quality fluctuates depending on the amount of interference power, and it is necessary to take a larger margin than when using the CIR as a reference.

[0041]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing a configuration of a mobile communication system to which the transmission power control method according to the present invention is applied.

In FIG. 4, a first mobile station 1a and a second mobile station 1b are connected to a first base station 3a via a radio line. Also, the reception CIR (hereinafter simply referred to as BSCIR1) for the first mobile station 1a in the first base station 3a.
a) and the first base station target CIR (hereinafter simply referred to as B
SCIR1) so that the difference between
Of the mobile station 1a is controlled, and the first base station 3a
CIR for the second mobile station 1b at
BSCIR2a) and the second base station target CI
The transmission power of the second mobile station 1b is controlled such that the difference from R (hereinafter simply referred to as BSCIR2) becomes smaller. Also, the first base station 3 in the first mobile station 1a
b and the first mobile station target CIR (hereinafter simply referred to as PSCIR1a).
R1) and the second
C at the mobile station 1b for the first base station 3a
IR (hereinafter simply referred to as PSCIR2a) and a second mobile station target CIR (hereinafter simply referred to as PSCIR2)
The transmission power of the first base station 3a is controlled so that the difference from the transmission power is reduced.

Next, the configuration of the base station 3 when the present invention is applied to the CDMA system will be described with reference to the block diagram of FIG. The configuration of the base station 3 shown in FIG.
a, 1b,..., but since the configuration corresponding to each is the same, FIG. 5 shows only a portion corresponding to two lines, and the description will be made only for a portion corresponding to one line. . Note that the antenna 11, the antenna duplexer 13, the receiving unit 15, and the transmitting unit 39 are shared by all wireless lines.

Referring to FIG. 5, the signal received by receiving section 15 through antenna 11 and antenna duplexer 13 is sent to first receiving correlator 17a (at this time, similarly, second receiving correlator 17a). 17b, third reception correlator 17
c ...). First receiving correlator 17a
Selectively outputs a received signal of a channel transmitted by the first mobile station 1a, which is demodulated by a first demodulator 19a and then sent to a first base station transmission power control information reading section 21a. . Here, the base station transmission power control information from the first mobile station 1a is read and transmitted to the first amplification unit 37a, while the information signal is transmitted to the communication network 5. In FIG. 5, the base station transmission power control information is attached to the information signal, but can be transmitted using another channel.

As to the transmission signal, the first mobile station transmission power control information adding section 31 is added to the information signal sent from the communication network 5.
a, the mobile station transmission power control information is added, and the first modulator 3
3a, and is spread by a first transmission correlator 35a corresponding to the channel received by the first mobile station 1a.
After being amplified by the amplifying unit 37a, the signal is sent to the transmitting unit 39, and is transmitted to the first mobile station 1a through the antenna duplexer 13 and the antenna 11.

Next, the transmission power control operation in the base station will be described with reference to FIG. First, the first CIR comparing section 29a compares the BSCIR1 stored in the first target CIR storage section 27a with the BSCIR1a obtained from the first demodulator 19a, and performs mobile station transmission based on the comparison result. The power control information is added by the first mobile station transmission power control information adding unit 31a. FIG. 6 shows an example of the mobile station transmission power control information.

As shown in FIG. 6, the transmission power control information of the mobile station takes a value from “0” to “8”, so that the transmission power is increased in a range of −2.0 dB to 2.0 dB in 0.5 dB steps. Can be controlled by Transmission power control information is B
The value is set so that SCIR1a approaches BSCIR1 as much as possible. Since the amount of change in the transmission power and the amount of change in the received CIR substantially match, for example, BSCIR1a
If it is 1.2 dB lower than 1, the transmission power control information is set to "6" (+1.0 dB). As a result, the transmission power after transmission power control increases by 1.0 dB, and the BSCIR
1a also increases by 1.0 dB, and BSCIR1a
It will approach IR1.

On the other hand, the first BER measuring unit 23a and the first number of reception paths and the fading pitch measuring unit 24a measure the BER, the number of reception paths, and the average value during one control period of the fading pitch, and perform the first reception. CIR distribution measuring unit 25
a, the distribution of BSCIR1a is measured, and BSCIR1 is set or changed based on the measurement results.

The transmission power of the base station 3 is controlled by changing the amplification factor in the first amplifier 37a based on the base station transmission power control information read by the first base station transmission power control information reader 21a.

Next, the configuration of the mobile station 1 when the present invention is applied to the CDMA system will be described with reference to FIG. Referring to FIG. 7, a signal transmitted by base station 3 is received by receiving section 4 through antenna 41 and antenna duplexer 43.
5, and is sent to the receiving correlator 47, demodulated by the demodulator 49, and sent to the mobile station transmission power control information reading section 51, where the mobile station transmission power control information from the base station 3 is read and amplified. While transmitting to 67, the information signal is transmitted to the terminal device 71. In this embodiment, the mobile station transmission power control information is attached to the information signal.
It is also possible to send using another channel.

As for the transmission signal, the base station transmission power control information adding section 61 adds base station transmission power control information to the information signal sent from the terminal device 71, modulates it with a modulator 63, and After being spread at 65 and amplified by the amplifying section 67, the signal is sent to the transmitting section 69 and transmitted to the base station 3 through the antenna duplexer 43 and the antenna 41.

Next, the transmission power control operation in the mobile station 1 will be described with reference to FIG. First, in the CIR comparison section 59, the PS stored in the target CIR storage section 57 is output.
A target CIR such as CIR1 and a PIR obtained from the demodulator 49.
A comparison is made with the received CIR such as SCIR1a, and base station transmission power control information addition section 61 adds base station transmission power control information based on the comparison result. The mobile station transmission power control information is the same as the transmission power control information shown in FIG.

On the other hand, the BER measurement unit 53 and the number of reception paths,
The fading pitch measuring unit 54 measures the BER, the number of reception paths, and the average value during one control cycle of the fading pitch, and the receiving CIR distribution measuring unit 55 measures the distribution of the receiving CIR. Set or change the CIR. The transmission power of the mobile station 1 is determined based on the mobile station transmission power control information read by the mobile station transmission power control information reading unit 51.
Is controlled by changing the amplification factor.

Hereinafter, the base station 3 and the mobile station 1 of this embodiment
Various methods for setting or changing the target CIR in the transmission power control between and will be described.

First, the first method will be described. First
In the method of (1), an example is shown in which the target CIR is changed based on the error of the reception CIR of each radio line from the target CIR.
In the first method, the target CIR of each radio line is
The distribution is controlled by the distribution of the received CIR periodically measured for each radio line by the distribution measuring unit 25 or 55. In this method,
Basically, both the mobile station 1 and the base station 3
Is measured, the distribution of the received CIR measured by the mobile station 1 and the distribution of the received CIR measured by the base station 3 have a correlation. It is also possible to control the target CIR, or conversely, to control the target CIR of the mobile station 1 based on the distribution of the received CIR measured by the base station 3.

Hereinafter, a method of controlling the target CIR in the mobile station 1 will be described. Target CIR at mobile station 1
C at the mobile station 1 when is set to 10 dB
FIGS. 8A and 8B show examples of the IR probability distribution. The distribution time is longer than the transmission power control interval (for example, if the transmission power control interval is 1 msec, the received CIR distribution is measured for 1 second).

As described above, when the mobile station is moving at a high speed or when the number of reception paths at the mobile station is small, the error of the received CIR from the target CIR as shown in FIG. And the distribution of the received CIR is widened. Conversely, when the mobile station is moving at a low speed or when the number of reception paths at the mobile station is large, the error of the received CIR from the target CIR becomes small as shown in FIG. Distribution becomes narrow.

In this system, the distribution of the received CIR is periodically measured for each radio line, and the required CIR is calculated according to the distribution.
The target CIR of each wireless channel is changed so that the probability that the above is not satisfied is, for example, 1% or less. FIGS. 8A and 8B
In the example of FIG. 8A, the target CIR is set to 9 dB in the case of FIG. 8A, and the target CIR is set to 6 dB in the case of FIG. In this case, the required CIR (5 dB) can be satisfied by 99%. In particular, in the case of FIG. 8B, the transmission power of the base station 3 to the mobile station 1 can be significantly reduced.

The method of controlling the target CIR in the base station 3 can be performed in exactly the same procedure as the control in the mobile station 1 described above.

As described above, according to the transmission power control method shown in the first method, as shown in FIG.
By reducing the target CIR for a mobile station having a smaller distribution width of the IR, the required communication quality can be satisfied and the transmission power can be reduced, so that the amount of interference given to other wireless lines decreases, and the subscriber capacity decreases. Increase.

When the first method is adopted, FIG.
7 and the mobile station of FIG.
3, the number of reception paths, fading pitch measuring units 24 and 5
4 and the configuration shown in FIGS. 11 and 12 can be obtained.

Next, the second method will be described. In the second method, an example is shown in which the target CIR is changed by the BER for each wireless channel. In the second method, the target CIR of each wireless channel is controlled based on a periodic measurement result of each wireless channel by the BER measuring unit 23 or 53. In this method, basically, both the mobile station 1 and the base station 3
The ER is measured. Since the measurement result at the mobile station 1 and the measurement result at the base station 3 are correlated, the target CIR of the base station 3 is controlled based on the measurement result at the mobile station 1 and vice versa. , The target CI of the mobile station 1 based on the measurement result at the base station 3
It is also possible to control R.

First, the BER is measured in the mobile station 1,
A method for controlling the target CIR in the mobile station 1 based on the measurement result will be described. Here, a simple example will be described. The mobile station 1 measures the BER over a longer time than the control interval of the transmission power control (for example, 1 second as in the case of the distribution measurement of the reception CIR). The BER is measured using, for example, a bit string portion of a fixed pattern for synchronization. If the measurement result is larger than a predetermined BER (for example, 10 ⁻³ ), the target CIR in the mobile station 1 is increased by 0.5 dB,
If smaller, the target CIR at the mobile station 1 is 0.5d
B lower. By repeating this operation, the received BER converges around the required BER.

As shown in FIGS. 13A and 13B, when the error of the received CIR from the target CIR is large, the target CIR
The IR becomes large, and when the error of the received CIR from the target CIR is small, the target CIR becomes small.
ER is a value close to the required BER. Therefore, the received CIR
Irrespective of the magnitude of the error from the target CIR, the received BER in all the mobile stations 1, that is, the communication quality becomes almost constant, and the transmission power can be reduced.

The method of controlling the target CIR in the base station 3 can be performed in exactly the same procedure as the control in the mobile station 1.

When this second method is adopted, FIG.
7 and the mobile station of FIG. 7 respectively have the number of reception paths, fading pitch measurement units 24 and 54 and reception CIR distribution measurement unit 2
The structure shown in FIGS.

Next, the third method will be described. The third method shows an example in which the target CIR of each wireless channel is changed according to the number of reception paths and the fading pitch for each wireless channel. FIG. 16 shows an example of the relationship between the number of reception paths and the fading pitch and the reception CIR error. As shown in FIG. 16, as the fading pitch is smaller,
The smaller the number of reception paths, the larger the error of the reception CIR from the target CIR. These relationships are uniquely determined if system parameters such as the transmission power control interval are determined. Accordingly, the distribution of the reception CIR of each radio channel can be estimated from the periodic measurement results of the number of reception paths and the fading pitch of each radio channel. Therefore, by performing the same control as in the first embodiment, the transmission power can be reduced. And an increase in subscriber capacity.

When this third method is adopted, FIG.
7 and the mobile station of FIG.
FIG. 1 in which the receiving CIR distribution measuring units 25 and 55 are omitted.
The configuration shown in FIGS.

As described above, according to the transmission power control methods shown in the second and third systems, the required communication quality can be satisfied and the transmission power can be reduced, as in the first embodiment. Therefore, the amount of interference given to other wireless lines decreases, and the subscriber capacity increases.

Next, the fourth method will be described. 4th
In the method described above, an example is shown in which the reception CIR distribution characteristics of each base station are learned or estimated, and the target CIR is set based on the results. In this fourth scheme, the target CI
Learning or estimation is performed by learning / estimating means configured by software or firmware provided in the R storage unit 27. The CPU or the like may be included in the target CIR storage unit 27 or may be provided separately.

The operation of this method will be described below. In the case of learning, the reception CIR distribution characteristics of each wireless channel are measured by the procedures shown in the first and third methods, and the results are totaled for each base station to obtain an average characteristic. Is stored as the learning result. Here, in an area such as an urban area where the number of reception paths is large and the moving speed of the mobile station is relatively slow, there is a high probability that the error of the received CIR from the target CIR is small.
In an area where the number of reception paths is small, such as a suburb, and the moving speed of the mobile station is relatively high, there is a high probability that the error of the reception CIR from the target CIR is large.

Based on the stored learning result, by setting the target CIR such that the probability that the received CIR falls below the required CIR is, for example, 1% or less, the transmission power can be reduced, and The capacity also increases. In the fourth method of setting a different target CIR for each base station,
Although it is impossible to deal with each mobile station, it is very useful, for example, when determining the initial value of the target CIR.

When estimating, the average number of reception paths and the moving speed are estimated from the building data in the service area by a known delay spread estimating method or the like, and the estimation result is stored. In this case, there is no need to measure the distribution of the received CIR as described in the first, second, and third schemes, so that the apparatus configuration is simplified and the amount of control is reduced. is there. That is, when the fourth system is adopted, the base station shown in FIG. 5 can be configured as shown in FIG. 19 in which the BER measurement unit 23, the number of reception paths, the fading pitch measurement unit 24, and the reception CIR distribution measurement unit 25 are omitted.

Next, the fifth method will be described. In the fifth method, an example is shown in which the received CIR distribution characteristics of each mobile station are learned, and the target CIR of each mobile station is set based on the learning result. In the fifth method, learning is performed by learning means provided in the target CIR storage unit 57 and configured by software or firmware, similarly to the fourth method. Note that the CPU and the like
It may be included in the IR storage unit 57 or may be provided separately.

As for the learning method, the reception CIR distribution characteristics of each radio channel are measured by the procedures shown in the first and third methods, the results are totaled for each mobile station, and the average characteristics are obtained. Obtained and stored as a learning result. There are a method of storing the learning result individually by the mobile station and a method of storing the learning result in a database on the base station side. Here, the error of the received CIR of the mobile station whose moving speed is relatively slow from the target CIR is small,
Target CIR of received CIR of mobile station with relatively fast moving speed
The error from is large. Therefore, the distribution characteristics of the received CIR also differ depending on the movement characteristics of the mobile station.

Based on the stored learning result, the target CIR is set such that the probability that the received CIR falls below the required CIR is, for example, 1% or less, so that the transmission power can be reduced. The capacity also increases.

When the fifth system is adopted, the structure shown in FIG.
The mobile station may be configured as shown in FIG. 20 omitting the BER measurement unit 53, the number of reception paths, the fading pitch measurement unit 54, and the reception CIR distribution measurement unit 55.

In the above-described embodiment, the reception CI
R may be generally a quantity indicating the reception level.
The R distribution, BER, and the like may be generally used as an amount indicating the line quality.

[0079]

As described above, according to the present invention,
By setting a different target CIR for each mobile station and each base station, it is possible to prevent each wireless channel from becoming excessively high quality, so that transmission power can be reduced and the total amount of interference can be reduced. In particular, the CDMA system has an effect that the subscriber capacity can be easily increased. Also, target CIR
Is automatically set based on the measurement result such as BER, so that there is an effect that the system design becomes easy.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a mobile communication system using a conventional transmission power control method.

FIG. 2 is a timing chart for explaining a conventional transmission power control method in the mobile communication system of FIG. 1;

FIG. 3 is a diagram for explaining the conventional transmission power control method of FIG. 2;

FIG. 4 is a block diagram showing a schematic configuration of a mobile communication system to which a transmission power control method according to the present invention is applied.

FIG. 5 is a block diagram showing a configuration of a base station to which the transmission power control method according to the present invention is applied.

FIG. 6 is a diagram showing an example of transmission power control information used in the transmission power control method of the present invention.

FIG. 7 is a block diagram showing a configuration of a mobile station to which the transmission power control method according to the present invention is applied.

FIG. 8: Received CI in the first method of changing the target CIR
The figure which shows the probability distribution of R.

FIG. 9 shows a target CI in the first method of changing the target CIR.
The figure which shows the probability distribution of the reception CIR after R change.

FIG. 10 shows a target CI in the transmission power control method of the present invention.
The figure for demonstrating the change of R.

FIG. 11 is a block diagram showing a configuration of a base station suitable for a first method of changing a target CIR.

FIG. 12 is a block diagram showing a configuration of a mobile station suitable for a first method of changing a target CIR.

FIG. 13 shows a target C in a second method of changing the target CIR.
FIG. 4 is a diagram for explaining IR control.

FIG. 14 is a block diagram showing a configuration of a base station suitable for a second method of changing a target CIR.

FIG. 15 is a block diagram showing a configuration of a mobile station suitable for a second method of changing a target CIR.

FIG. 16 is a diagram for explaining the relationship between the number of reception paths and the fading pitch and the variance of reception CIR in the third method of changing the target CIR.

FIG. 17 is a block diagram showing a configuration of a base station suitable for a third method of changing a target CIR.

FIG. 18 is a block diagram showing a configuration of a mobile station suitable for a third method of changing a target CIR.

FIG. 19 is a block diagram showing a configuration of a base station suitable for a fourth scheme for setting a target CIR.

FIG. 20 is a block diagram showing a configuration of a mobile station suitable for a fifth scheme for setting a target CIR.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mobile station 3 base station 5 communication network 11 antenna 13 antenna duplexer 15 reception unit 17 reception correlator 19 demodulator 21 base station transmission power control information reading unit 23 BER measurement unit 24 number of reception paths, fading pitch measurement unit 25 reception CIR distribution measuring unit 27 target CIR storage unit 29 CIR comparing unit 31 mobile station transmission power control information adding unit 33 modulator 35 transmitting correlator 37 amplifying unit 39 transmitting unit 41 antenna 43 antenna duplexer 45 receiving unit 47 receiving correlator 49 Demodulator 51 Mobile station transmission power control information reading unit 53 BER measurement unit 54 Number of reception paths, fading pitch measurement unit 55 Reception CIR distribution measurement unit 57 Target CIR storage unit 59 CIR comparison unit 61 Base station transmission power control information addition unit 63 Modulator 65 Transmission correlator 67 Amplifying unit 69 Transmitting unit 71 Terminal device

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-244056 (JP, A) JP-A-6-132871 (JP, A) JP-A-8-1667872 (JP, A) 500228 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 7/26 H04Q ⁷ /00-7/38

Claims (26)

(57) [Claims] 1. A transmission power control method in a mobile communication system including a base station and a mobile station, the method comprising: controlling transmission power of a radio channel in one of the base station and the mobile station between the base station and the mobile station. Controlling the difference between the reception CIR (carrier interference ratio) of the radio channel at the other station and the target CIR; and reducing the channel quality of the radio channel at either the base station or the mobile station. Periodically measuring at one of the stations the distribution of the received CIR for each of the radio lines shown in the table, and a target for each radio line at the other station based on the distribution of the received CIR measured by the measuring step. Changing the CIR. 2. The method according to claim 1, wherein the changing includes changing the target CIR such that a probability that the received CIR becomes lower than a required CIR in a distribution of the received CIR measured by the measuring step is equal to or less than a predetermined value. The transmission power control method according to claim 1. 3. A transmission power control method in a mobile communication system including a base station and a mobile station, wherein the transmission power of a radio channel in one of the base station and the mobile station is controlled by the transmission power of the base station and the mobile station. Controlling the difference between the reception CIR (carrier interference ratio) of the radio channel at the other station and the target CIR; and reducing the channel quality of the radio channel at either the base station or the mobile station. Periodically measuring the number of reception paths and the fading pitch of each of the indicated radio lines in one of the stations; and, based on the number of reception paths and the fading pitch measured in the measuring step, the radio in the other station. Changing the target CIR for each line. 4. The changing step estimates a reception CIR distribution from the number of reception paths and a fading pitch measured in the measurement step, and the reception CIR is lower than a required CIR in the estimated reception CIR distribution. 4. The transmission power control method according to claim 3, wherein the target CIR is changed so that the probability is equal to or less than a predetermined value. 5. A transmission power control method in a mobile communication system including a base station and a mobile station, wherein the transmission power of a radio channel in one of the base station and the mobile station is controlled by the transmission power of the base station and the mobile station. Controlling the difference between the received CIR (carrier interference ratio) of the wireless channel at the other station and the target CIR; and controlling the line quality of the wireless channel at either the base station or the mobile station. Setting the target CIRs of all the radio links in the other station based on the other station based on the other station. 6. An average line quality characteristic in the other station based on the step of measuring the reception quality of each radio line in one of the stations and the line quality measured in the step of measuring the other station. 6. The transmission power according to claim 5, further comprising a step of learning the target CIR based on an average channel quality characteristic learned in the learning step. Control method. 7. A method for measuring a distribution of a reception CIR for each radio line at one of said stations and a reception CIR measured at said other station.
Average received CIR at the other station from IR distribution
6. The transmission according to claim 5, further comprising a step of learning a distribution, wherein the setting step sets the target CIR based on an average received CIR distribution learned by the learning step. Power control method. 8. The setting step includes setting the target CIR such that the probability that the received CIR becomes lower than a required CIR in a distribution of average received CIRs learned in the learning step is equal to or less than a predetermined value. The transmission power control method according to claim 7, wherein: 9. a step of measuring a BER (bit error rate) for each radio line in one of the stations;
Learning the average BER in the other station from the BER measured in the measuring step in the other station, and the setting step is a step in which the average BER learned in the learning step is learned. BE
The transmission power control method according to claim 5, wherein the target CIR is set based on R. 10. The setting step is a step in which the average BER learned in the learning step is a required BE.
When the value is smaller than R, the target CIR is decreased, and the average BER learned in the learning step is equal to a required B.
The transmission power control method according to claim 9, wherein the target CIR is increased when the transmission power is larger than the ER. 11. The step of measuring the number of reception paths and the fading pitch for each radio link in one of the stations, and the other station from the number of reception paths and the fading pitch measured by the measuring step in the other station. Learning the average number of reception paths and the average fading pitch in the station, wherein the setting step includes calculating the average number of reception paths and the average fading pitch learned by the learning step. 6. The transmission power control method according to claim 5, wherein the target CIR is set based on the target CIR. 12. The setting step estimates an average reception CIR distribution from an average number of reception paths and an average fading pitch learned in the learning step, and calculates the estimated average reception CIR. 12. The transmission power control method according to claim 11, wherein the target CIR is set such that a probability that a received CIR is lower than a required CIR in a distribution is equal to or less than a predetermined value. 13. The other station is a base station, further comprising a step of estimating a reception CIR distribution at the base station from data of a building in an area covered by the base station, wherein the setting step is 6. The transmission power control method according to claim 5, wherein the target CIR is set such that a probability that the received CIR becomes lower than a required CIR in a distribution of the received CIR estimated in the estimating step is equal to or less than a predetermined value. . 14. The transmission power control method according to claim 1, wherein the target CIR and the reception CIR are given by a target level and a reception level. 15. A transmission power control method in a mobile communication system including a base station and a mobile station, wherein the transmission power of a radio channel in one of the base station and the mobile station is controlled by the transmission power of the base station and the mobile station. Controlling the difference between the reception CIR (carrier interference ratio) of the radio channel at the other station and the target CIR; and reducing the channel quality of the radio channel at either the base station or the mobile station. Measuring at one of the stations, and changing a target CIR for each radio link at the other station to a required minimum value that makes the line quality measured at the measuring step a required value or more. Transmission power control method characterized by the above-mentioned. 16. A base station communicating with a mobile station in a mobile communication system, wherein a transmission power of a radio channel in the mobile station is determined by a reception CIR (carrier interference ratio) of the radio channel in the base station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a unit for measuring the line quality of the wireless line in the one of the stations, and the changing unit needs to set the line quality measured by the measuring unit to a required value or more. The target C
A base station for changing IR. 17. A mobile station communicating with a base station in a mobile communication system, wherein a transmission power of a radio channel in the base station is determined by a reception CIR (carrier interference ratio) of the radio channel in the mobile station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a unit for measuring the line quality of the wireless line in the one of the stations, and the changing unit needs to set the line quality measured by the measuring unit to a required value or more. The target C
A mobile station characterized by changing IR. 18. A transmission power control method in a mobile communication system including a base station and a mobile station, wherein the transmission power of a radio channel in one of the base station and the mobile station is controlled by the transmission power of the base station and the mobile station. Controlling the difference between the reception CIR (carrier interference ratio) of the radio channel at the other station and the target CIR; and reducing the channel quality of the radio channel at either the base station or the mobile station. Periodically measuring the indicated BER (bit error rate) at one of the stations, and when the BER measured by the measuring step is larger than a required BER, a target CIR for each radio link at the other station is calculated. Increasing and decreasing the target CIR per radio link at the other station when the BER measured by the measuring step is less than a required BER. And a transmission power control method. 19. A base station communicating with a mobile station in a mobile communication system, wherein a transmission power of a radio channel in the mobile station is determined by using a reception CIR (carrier interference ratio) of the radio channel in the base station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a unit for periodically measuring a BER (bit error rate) indicating a line quality of a radio link in the one of the stations, and the changing unit measures the BER by the measuring unit. The target CIR when the given BER is greater than the required BER
And increasing the target CIR when the BER measured by the measuring means is smaller than a required BER. 20. A mobile station communicating with a base station in a mobile communication system, wherein a transmission power of a radio channel in the base station is determined by a reception CIR (carrier interference ratio) of the radio channel in the mobile station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a unit for periodically measuring a BER (bit error rate) indicating a line quality of a wireless line in the one of the stations; and the changing unit measures the BER by the measuring unit. The target CIR when the given BER is greater than the required BER
And increasing the target CIR when the BER measured by the measuring means is smaller than a required BER. 21. A base station communicating with a mobile station in a mobile communication system, wherein a transmission power of a radio channel in the mobile station is determined by a reception CIR (carrier interference ratio) of the radio channel in the base station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a means for periodically measuring the distribution of the reception CIR for each wireless line indicating the line quality of the wireless line in the one of the stations, and the changing means comprises the measuring means A base station for changing the target CIR based on a distribution of received CIR measured by the base station. 22. A mobile station communicating with a base station in a mobile communication system, wherein a transmission power of a radio channel in the base station is determined by a reception CIR (carrier interference ratio) of the radio channel in the mobile station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a means for periodically measuring the distribution of the reception CIR for each wireless line indicating the line quality of the wireless line in the one of the stations, and the changing means comprises the measuring means And changing the target CIR based on the distribution of the received CIR measured by the mobile station. 23. A base station communicating with a mobile station in a mobile communication system, wherein a transmission power of a radio channel in the mobile station is determined by a reception CIR (carrier interference ratio) of the radio channel in the base station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a unit for periodically measuring the number of reception paths and a fading pitch for each radio line indicating the line quality of the radio line in the one of the stations, and the changing unit includes the measurement unit. And changing the target CIR based on the number of reception paths and the fading pitch measured by the means. 24. A mobile station communicating with a base station in a mobile communication system, wherein a transmission power of a radio channel in the base station is determined by a reception CIR (carrier interference ratio) of the radio channel in the mobile station. Means for controlling the difference from the target CIR to be small, and means for changing the target CIR for each radio line based on the line quality of the radio line in either the base station or the mobile station. The one of the stations has a unit for periodically measuring the number of reception paths and a fading pitch for each radio line indicating the line quality of the radio line in the one of the stations, and the changing unit includes the measurement unit. A mobile station that changes the target CIR based on the number of reception paths and the fading pitch measured by the means for performing the operation. 25. A base station communicating with a mobile station in a mobile communication system, wherein a transmission power of a radio channel in the mobile station is determined by a reception CIR (carrier interference ratio) of the radio channel in the base station. Means for controlling the difference from the target CIR to be small; and setting the target CIRs of all the radio channels in the base station to the base station based on the channel quality of the radio channel in one of the base station and the mobile station. A base station having means for setting each station. 26. A mobile station communicating with a base station in a mobile communication system, wherein the transmission power of a radio channel in the base station is determined by the reception CIR (carrier interference ratio) of the radio channel in the mobile station. Means for controlling the difference from the target CIR to be small, and moving the target CIRs of all the radio links in the mobile station based on the channel quality of the radio links in either the base station or the mobile station. Means for setting for each station.