JPH11298407A - Mobile communication system, base station device, mobile station device and transmission power controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a system capacity large and also to avoid sharp gradation of system performance at high traffic by calculating the target receiving power value of a signal received by a base station, based on traffic quantity and allowing a mobile station to calculate a transmission power value with the target receiving power value as a reference. SOLUTION: A base station 20 receives a signal of an access channel 31 which is transmitted by mobile stations 11 to 13 and a transmitter-receiver 22 demodulates it. A traffic measuring part 24 measures traffic quantity and outputs it as traffic information. A target receiving power information calculating part 25 calculates a target receiving power value from the traffic information. A baseband signal processing part 23 stores attribute information of mobile stations and target receiving power information corresponding to it in a prescribed block of informative channel information and the transmitter-receiver 22 transmits the signal to the stations 11 to 13 through an informative channel 30. The stations 11 to 13 calculate transmission power of a transmission packet from the target receiving power information and receiving power of the channel 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mobile communication system, a base station apparatus, a mobile station apparatus, and a transmission power control method, and more particularly to packet communication between a plurality of mobile stations and a base station using a common channel. The present invention relates to a mobile communication system, a base station apparatus, a mobile station apparatus, and a transmission power control method for performing random access by a CDMA (code division multiple access) method.

[0002]

2. Description of the Related Art In uplink communication from a mobile station to a base station in a mobile communication system using a CDMA (code division multiple access) system as a multiple access system, a signal from each mobile station is transmitted at the base station. Performance degradation (so-called near-far problem) caused by the difference in the received power due to the difference in the distance between the base station and the mobile station is a major problem. In order to alleviate the near-far problem, mobile communication systems using the CDMA system generally reduce the transmission power at the time of mobile station transmission so that the reception power at the base station of the signal from each mobile station is equal. Controlling transmission power control is performed.

On the other hand, in a wireless packet transmission system, channel control such as allocating an empty channel at the time of a call is not performed as in a mobile phone system, and data is immediately transmitted on the same channel in synchronization with a slot, for example, in a slot aloha system. A method of transmitting a packet is used. In this case, a large number of signals may collide, but in a system employing a narrowband multiple access system (FDMA, TDMA system), the reception power difference at the base station of the signal from each mobile station causes It is known that there is an effect that a packet can be received under a certain condition even in a collision state (a so-called capture effect).

[0004]

[Problems to be Solved by the Invention] Regarding the effect of transmission power control in a system that performs packet transmission using the CDMA system, see "Effect of transmission power control in mobile packet CDMA communication", 1996 IEICE General Conference lecture paper. Communication
[1], March 1996, p.374. According to this document, when transmission power control is introduced in a system that performs slot Aloha packet transmission using the CDMA system, the system capacity (maximum point of throughput) increases, but the traffic increases and the maximum throughput increases. Beyond the point, there is a disadvantage that the system performance is rapidly deteriorated.

[0005] This is because transmission power control is performed so that the received signal powers at the base station are all equal. However, when the traffic increases, the number of signals multiplexed in the same frequency band increases, and the signals of other stations increase. Are all noise powers, so that the S / N ratios of the received signals of all mobile stations are lower than the receivable level.

When transmission power control is not performed in a packet transmission system using the CDMA system, a sharp effect of the system performance in a high traffic state is not observed because a capture effect is obtained. However, there is a drawback that the maximum point of the throughput is small as compared with the transmission power control. Further, when the transmission power control is not performed, the transmission power of the packet at the mobile station is constant, so that the shorter the distance between the base station and the mobile station, the higher the reception power at the base station. Therefore, there is a disadvantage that the reception probability of a transmission packet of a mobile station close to the base station is larger than the reception probability of a mobile station far from the base station, and there is an unfairness of communication due to the geographical conditions of the mobile station.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been made to increase the system capacity (the maximum point of the throughput) and to avoid the rapid deterioration of the system performance at the time of high traffic. It is another object of the present invention to provide a mobile communication system and a transmission power control method capable of reducing communication unfairness due to geographical conditions of a mobile station.

[0008]

In order to achieve the above object, the present invention comprises a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the base station and the mobile station in the communication area are provided. In a mobile communication system that performs communication with a mobile station by using a wireless channel of the same frequency band, a traffic measuring unit that measures a traffic amount of the wireless channel, and a target reception in the base station based on the traffic amount of the wireless channel. It has a target reception power calculation means for calculating a power value, and a transmission means for transmitting a signal at a transmission power obtained based on a target reception power value that matches its own attribute.

In the present invention, when the traffic on the radio channel is small, the same control as the normal transmission power control is performed to increase the system capacity, and when the traffic on the radio channel increases, ,
Based on the attribute of each mobile station, a difference can be provided between the target reception power values at the base station, and the probability of successful transmission due to the capture effect can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a system device configuration according to the first embodiment of this invention. In FIG.
A plurality of mobile stations 11, 12, 13 in the service area 10
When the mobile station 11 communicates with another terminal (not shown) via the base station 20 and the wired line 26, the mobile stations 11, 12, and 13 use the common access channel 31 at an arbitrary timing or in a predetermined slot. The packet is transmitted to the base station 20 in synchronization with the packet. Note that there may be four or more mobile stations. Further, the spread code in the CDMA scheme may be fixedly assigned to the mobile station, for example, or may be a scheme in which the mobile station randomly selects a code that can be received by the base station.

When the base station 20 receives the signal of the access channel 31 transmitted by the mobile stations 11, 12, and 13 by the antenna 21, the base station 20 demodulates the signal by the transceiver 22, and converts the received baseband signal to the baseband signal processing unit 23 and the traffic. Output to the measuring unit 24. In the traffic measurement unit 24,
For example, the number of effective received packets per unit time is measured as the traffic amount. The traffic measurement unit 24
The measurement result is output to the target reception power information calculation unit 25 as traffic information. Target received power information calculation unit 25
Calculates a target received power value from the traffic information.
The target reception power information calculated by the target reception power information calculation unit 25 includes a plurality of values that differ for each attribute of the mobile station.

FIG. 2 is an explanatory diagram showing an example of the contents of a table used when obtaining a target received power value from the number of valid received packets. FIG. 2 is a table when three types of mobile station attributes are defined. The table of FIG. 2, for example,
It is conceivable to store the information in the memory in the target reception power information calculation unit 25. The target reception power information calculation unit 25 obtains a target reception power value corresponding to the traffic information measured by the traffic measurement unit 24 using the table shown in FIG. 2 and outputs the target reception power value to the baseband processing unit 23.

Now, when the traffic amount THm measured by the traffic measuring unit 24 is TH1 <THm <TH2, the target received power information calculating unit 25 uses the table of FIG. , POW for attribute 2
22, Calculate POW23 for attribute 3. These target reception power information obtained by the target reception power information calculation unit 25 are:
It is output to the baseband processing unit 23.

Although specific examples of the attribute and the target reception power information will be described later, the attribute may be, for example, a measured or estimated distance from the base station, and each of the target reception power information has low traffic. Sometimes, there is no difference or a small difference due to the difference in attributes, and the difference may increase as the traffic increases.

The baseband processing unit 23 that has received the target reception power information stores the attribute information of the mobile station and the target reception power information corresponding thereto in a predetermined block of the broadcast channel information, and outputs the information to the transceiver 22. The transceiver 22 transmits a signal including the attribute information of the mobile station and the corresponding target reception power information through the broadcast channel 30 to the mobile stations 11, 12,.
13 is transmitted.

The target received power information calculation unit 25 may calculate the target received power value by calculation instead of using the table as shown in FIG. In this case, a rule for obtaining the target reception power value from the traffic information is determined. For example, a target reception power value POW1 corresponding to an attribute 1 (highest priority attribute) mobile station, an initial value of the difference ΔPOW between the mobile station attributes of the target reception power value and a rule for changing the difference ΔPOW are determined in advance, and each mobile station is determined. The target received power value of the station attribute is obtained. For example, the difference ΔPOW (t) at time t is defined as follows.

[0017]

(Equation 1)

Then, a target reception power value POWi (t) of each attribute at time t is obtained by the following equation.

[0019]

(Equation 2)

In this example, the traffic measuring unit calculates the traffic amount based on the number of valid packets received by the base station per unit time, and the target received power calculating unit determines that the traffic amount measured by the traffic measuring unit is the maximum. Thus, the difference between the calculated target received power values corresponding to the attributes is adaptively set to calculate the target received power.

FIG. 3 shows the mobile station 11 in the present embodiment.
It is a flowchart which shows the operation flow of 12, 13. The mobile stations 11, 12, and 13 are in an idle state (S10) in a normal state. When the broadcast information is received from the base station 20 in this state, the old target received power information stored so far is discarded, and the target received power information included in the received broadcast information matches the own attribute. The target reception power information is selected, newly stored as target reception power information (S14), and the process returns to the idle state S10 again.
When a packet to be transmitted is generated, the mobile stations 11, 12, and 13 shift to S11 and calculate the transmission power of the transmission packet from the target reception power information stored in the mobile station and the reception power of the broadcast channel 30. (S11). Next, S
A signal of the transmission packet is transmitted to the access channel 31 with the transmission power calculated in step S11 (S12), and a response waiting state S1
Move to 3.

When the notification information from the base station 20 is received in the response waiting state S13, the idle state S10
The target reception power information is updated in the same manner as in (1).
5). The packet transmission process generally ends when a reception acknowledgment (ACK) signal is received from the base station 20, and in this case, the process returns to the idle state (S10) again. If an ACK signal cannot be received within a predetermined time, the process returns to S1
The process returns to 1 to perform packet retransmission processing.

When the attribute of the mobile stations 11, 12, and 13 is the reception power of the signal transmitted from the connected base station 20 (for example, the signal of the broadcast channel 30) at the mobile stations 11, 12, and 13, for example, When the mobile stations 11, 12, and 13 receive the broadcast information, the mobile stations 11, 12, and 13 simultaneously measure the reception power of the broadcast channel 30. The operation of updating the target received power using the measured received power value as its own attribute information (S14, S1)
Execute 5).

When the attributes of the mobile stations 11, 12, and 13 are distances from the connected base station 20, for example, a positioning system such as a GPS is mounted on the mobile station as distance measuring means. Then, by broadcasting the position information of the base station 20 on the broadcast channel 30, the distance between the base station and the mobile station in the mobile station is calculated. The mobile stations 11, 12, and 13 execute the operation of updating the target reception power using the distance between the base station and the mobile station calculated as described above as their own attribute information.

FIG. 4 is a graph showing a change in the transmission power of the mobile station depending on the distance when ordinary transmission power control is performed. Regardless of the distance from the base station, the transmission power of each mobile station is controlled such that the signals of any mobile station are all received at the same level at the base station. The distance information is estimated from this value by actually calculating the distance using the positioning system or measuring the reception power of the broadcast channel from the base station. That is, when the reception power of the broadcast channel is low, the transmission power is increased. Therefore, the transmission power increases as the distance from the periphery of the cell increases, and interference with adjacent cells increases.

FIG. 5 is a graph showing transmission power control according to the present invention when the traffic volume is large. In this case, for example, the mobile station is divided into three attributes according to the distance, and a target reception power value as illustrated is assigned to each attribute. That is, for example, the base station is assigned a power lower by ΔPOW to the mobile station of the attribute 2 of the medium distance with respect to the mobile station of the attribute 1 of the short distance, and further assigned to the mobile station of the attribute 3 of the long distance For example, 2 × ΔPOW
Allocate only lower power. The allocated power is, for example,
The value is set to a value between the power when the normal transmission power control is performed and the power when the transmission power control is not performed.

By performing such transmission power control, for example, the greater the traffic volume, the greater the difference in reception power at the base station, and the capture effect improves the success rate of packet transmission as compared with conventional transmission power control. I do. Further, in the peripheral part of the cell, the transmission power of the mobile station becomes smaller than in the case where normal transmission power control is performed, and interference with adjacent cells is reduced.

FIG. 6 is a block diagram showing a configuration of a base station according to the second embodiment of the present invention. In FIG.
1 are given the same reference numerals as in FIG. In this embodiment, the base station 40 broadcasts the traffic information, and the mobile station receives the traffic information and calculates the target received power. Therefore, compared to the base station 20 of FIG. 1, the base station 40 of FIG. 6 does not have the target reception power calculation unit. In the base station 40 of the second embodiment, the baseband processing unit 23 receives the traffic information measured by the traffic measuring unit 24, stores the traffic information in a predetermined block of the broadcast channel information, and outputs the traffic information to the transceiver 22. . The transceiver 22 transmits a signal including traffic information to the mobile station through the broadcast channel 30.

The mobile station previously stores the same table as the table shown in FIG. 2 in a memory in the mobile station. When receiving the broadcast information from the base station 40, the base station 40 calculates its own target received power information using the table of FIG. 2 based on the traffic information and its own attribute information included in the received broadcast information. Thereafter, the old target reception power information stored so far is discarded, and the newly calculated value is stored in the mobile station as the target reception power information.

The operation of the mobile station is the same as the operation flow shown in FIG. 3 except that the target reception power information is calculated from the traffic information and the table when the target reception power is updated. Further, as a method of calculating the target reception power information in the mobile station, a method of determining a rule for obtaining the target reception power value from the traffic information described in the first embodiment may be used.

Next, a third embodiment of the present invention will be described. In the present embodiment, the base station 20 calculates a target reception power setting function based on the traffic information. Then, a parameter specifying the target reception power setting function is transmitted to the mobile station through the broadcast channel 30. The mobile station reconfigures the target reception power setting function from the received parameter information, and determines the target reception power value from the target reception power setting function based on the attributes of the mobile station.

Since the configuration and operation of the third embodiment are similar to those of the first embodiment, the description will focus on the differences.
In the third embodiment, a target reception power setting function calculation unit 50 is provided instead of the target reception power information calculation unit 25 in the base station 20 of FIG. Target reception power setting function calculation unit 5
0 calculates the target reception power setting function from the traffic information. The target reception power setting function calculated by the target reception power setting function calculation section 50 is a function having the attribute value of the mobile station on the horizontal axis and the target reception power value on the vertical axis.

FIG. 7 is an explanatory diagram showing an example of the target reception power setting function. The target reception power setting function shown in FIG. 7 takes a constant target reception power value POW0 up to a certain attribute value (inflection point: Rip), and thereafter, the target reception power value changes at a constant gradient a. It is represented by a function. The target reception power setting function calculation unit 50 determines a parameter for specifying the target reception power setting function, for example, the inflection point Rip and the slope a based on the traffic information in the target reception power setting function of FIG.

FIG. 8 is a table used for obtaining the inflection point Rip and the slope a, which are the parameter information of the target reception power setting function. The table in FIG. 8 may be stored in a memory in the target reception power setting function calculation unit 50, for example. Target reception power setting function calculation section 50
Is an inflection point Rip corresponding to the traffic information measured by the traffic measuring unit 24 using the table shown in FIG.
And the slope a are obtained and output to the baseband processing unit 23.

Now, when the traffic amount THm measured by the traffic measuring unit 24 is TH1 <THm <TH2, the target reception power setting function calculation unit 50 uses the table of FIG. Rip2,
The slope is determined as a2. Target reception power setting function calculation section 50
Are output to the baseband processing unit 23. The parameter information is such that the difference due to the attribute value difference in the target received power is not present or small when the traffic volume is small, and the difference increases as the traffic volume increases, that is, the inflection point Rip decreases as the traffic volume increases. , The inclination a may be set to be large.

The baseband processing unit 23 having received the parameter information of the target reception power setting function stores the parameter information in a predetermined block of the broadcast channel information and outputs the parameter information to the transceiver 22. The transceiver 22 transmits a signal including parameter information to the mobile stations 11 and 1 through the broadcast channel 30.
Send to 2 and 13. Target reception power setting function calculation section 50
Instead of using the table as shown in FIG. 8, parameter information of the target reception power setting function may be obtained by calculation. In this case, rules for obtaining parameter information from traffic information are determined. For example, inflection point Rip
Is a constant value, and the slope a is changed according to the traffic information. The value of the inflection point Rip may be, for example, １ ／ of the radius of the service area of the base station. A target reception power setting function y (x, t) at time t is determined as in the following equation.

[0037]

(Equation 3)

Then, the gradient a (t) at the time t is defined as follows.

[0039]

(Equation 4)

In this example, the traffic measuring unit obtains a traffic amount based on the number of valid packets received by the base station per unit time, and the target reception power setting function calculating means includes:
The target reception power setting function is calculated by adaptively setting the slope of the target reception power setting function so that the traffic amount measured by the traffic measuring means is maximized.

Next, the operation of the mobile station according to the third embodiment will be described. The operation of the mobile station is the same as the flowchart of the first embodiment shown in FIG. 3 except that the processing content of S14 or S15 and S11 is different. When the mobile station receives the broadcast information from the base station 20, in S14 or S15, it discards the parameter information of the old target reception power setting function stored so far, and replaces the existing parameter information in the received broadcast information with a new one. And returns to the idle state S10 or the response waiting state S13 again.

When a packet to be transmitted is generated, the mobile station proceeds to S11, reconfigures the target reception power setting function from the parameter information stored in the mobile station, and sets the target reception power setting function corresponding to the attribute value of the mobile station. Calculate the received power value. The processing contents of the other steps are the same as those of the first embodiment.

Although the embodiments have been disclosed above, the following modified examples are also conceivable. As an embodiment, an example in which the traffic volume is measured at the base station has been disclosed.
By measuring the traffic volume at the mobile station,
The present invention can be implemented only by processing on the mobile station side.
For example, the traffic volume may be estimated based on the packet transmission failure rate. That is, it may be considered that the greater the number of packet retransmissions, the greater the traffic volume, and the greater the power difference depending on the attribute value according to the number of packet retransmissions.

As an attribute, an example is disclosed in which the measured distance from the base station or the reception power of the broadcast channel substantially corresponding to the measured distance is adopted. In this case, the interference applied to the adjacent cells is equally distributed. Although it is smaller than the case where the transmission power control is performed, there is a problem that a mobile station closer to the base station becomes advantageous. To solve this, for example, mobile stations are randomly divided into a plurality of groups, and different attributes are assigned to each group. Then, this assignment is sequentially changed at a constant cycle. In this way, the priorities change periodically and become even when averaged. Further, in the case of emergency information or the like, the attribute of the terminal may be modified according to the attribute of the data so that the target received power value increases.

Although the example in which the traffic volume to be measured is the number of valid received packets for each predetermined time has been disclosed, if the traffic increases extremely, it becomes impossible to receive packets, and the number of valid received packets decreases instead. There is a risk of doing it. Therefore, the traffic amount may be estimated from the total received power at the base station.

[0046]

As described above, according to the mobile communication system and the transmission power control method of the present invention, when the traffic volume is small, the target received power is fixed regardless of the attribute of the mobile station, and the traffic volume is reduced. When it becomes larger, a different target reception power is set depending on the attribute of the mobile station, and the mobile station performs packet transmission with the target reception power that matches its own attribute. Therefore, when the attribute of the mobile station is the reception power of the radio wave emitted from the base station or the measured distance between the mobile station and the connected base station, it is possible to suppress the transmission power of the mobile station having a large transmission power in a high traffic state. Therefore, there is an effect that interference power to other cells is reduced, and it is possible to avoid rapid deterioration of system performance due to a capture effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a system device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a table for calculating a target received power value.

FIG. 3 is a flowchart showing an operation flow of a mobile station.

FIG. 4 is a graph showing a change in transmission power in normal transmission power control.

FIG. 5 is a graph showing a change in transmission power when the traffic volume is large.

FIG. 6 is a block diagram illustrating a configuration of a base station according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating an example of a target reception power setting function.

FIG. 8 is an explanatory diagram showing an example of a table for obtaining parameter information of a target reception power setting function.

[Explanation of symbols]

10: service area, 11, 12, 13 ... mobile station, 2
0, 40: base station, 21: antenna, 22: transceiver,
23: baseband processing unit, 24: traffic measurement unit, 25: target reception power calculation unit, 26: wired line, 30
... Broadcast channel, 31 ... Access channel

Claims (19)

[Claims] 1. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, and performing communication by a radio channel between the base station and the mobile station. Traffic measurement means for measuring a traffic amount of a wireless channel; target reception power calculation means for calculating a target reception power value of a signal received by the base station based on the measured traffic amount and an attribute of the mobile station; A mobile communication system, comprising: a mobile station that calculates a transmission power value based on the target reception power value and transmits a signal at the transmission power value. 2. The traffic measuring means is provided in the base station, the target received power calculating means is provided in the base station, and a target received power value of a signal received by the base station is set to an attribute of the mobile station. The base station further includes target reception power information notifying means for notifying the mobile station of all the target reception power information calculated for each of the attributes, , Comprising target reception power information receiving means for receiving the target reception power information, wherein the transmission means selects a target reception power value corresponding to the attribute of the own station from the received target reception power information, and selects The mobile communication system according to claim 1, wherein the transmission power value of the transmission signal is calculated based on the target reception power value. 3. The traffic measuring means is provided in the base station, and the base station further comprises traffic information notifying means for notifying the mobile station of the traffic amount, wherein the mobile station receives the traffic amount information. The target reception power calculation means is provided in the mobile station, and calculates a target reception power value based on the attribute and traffic amount information received from the base station. The mobile communication system according to claim 1, wherein 4. The target reception power setting function provided in the base station, wherein the target reception power calculation means determines a function based on an output of the traffic measurement means provided in the base station. Calculating means, and setting function information notifying means for notifying the mobile station of parameter information for specifying the target received power setting function calculated by the target received power setting function calculating means, and provided in the mobile station. Setting function information receiving means for receiving the parameter information, reconstructing a target reception power setting function from the received parameter information, and determining a target reception power value from the target reception power setting function based on attributes of the own station. 2. The mobile communication system according to claim 1, wherein the mobile communication system comprises a target received power value determining unit that performs the setting. 5. The mobile communication system according to claim 1, wherein the attribute is determined based on distance information between the mobile station and the base station measured at the mobile station. 6. The mobile communication system according to claim 1, wherein the attribute is determined based on a signal power value received from the base station at the mobile station. 7. The target reception power calculation means, based on a traffic amount measured by the traffic measurement means,
4. The mobile communication system according to claim 1, wherein the target received power is calculated by adaptively setting a difference between calculated values of the target received power corresponding to the attribute. 5. 8. The target reception power setting function has a constant target reception power value below a predetermined attribute value, and a linear function in which the target reception power value changes at a constant slope above the predetermined attribute value. The mobile communication system according to claim 4, wherein: 9. An attribute of the mobile station is determined based on distance information between the mobile station and the base station measured at the mobile station, and the predetermined attribute value is set to one of a radius of a service area of the base station. 9. The mobile communication system according to claim 8, wherein the ratio is set to / 2. 10. The target reception power setting function calculating means calculates the target reception power setting function by adaptively setting a slope of the target reception power setting function based on the traffic amount measured by the traffic measuring means. 10. The mobile communication system according to claim 8, wherein 11. The traffic measurement unit calculates a traffic amount based on the number of valid packets received by the base station per unit time, and the target reception power calculation unit increases the traffic amount measured by the traffic measurement unit. 4. The mobile communication system according to claim 1, wherein the target reception power is calculated by adaptively setting a difference between the calculated values of the target reception power corresponding to the attribute. 12. The traffic measuring unit obtains a traffic amount based on the number of valid packets received by the base station per unit time. The target reception power setting function calculating unit calculates the traffic amount measured by the traffic measuring unit. 11. The mobile communication system according to claim 8, wherein the target reception power setting function is calculated by adaptively setting a slope of the target reception power setting function so as to increase the value. 13. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile communication system performs communication between the base station and the mobile station via a radio channel. A base station apparatus, comprising: a traffic measurement unit; a target reception power calculation unit configured to calculate a plurality of target reception power values of signals received by the base station according to the measured traffic amount and attributes of the mobile station; A base station apparatus comprising: a target reception power information notifying unit that notifies the mobile station of all the target reception power information calculated for each attribute. 14. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile station is used in a mobile communication system for performing communication by a radio channel between the base station and the mobile station. A base station device comprising: a traffic measuring unit; and a traffic information notifying unit that notifies a mobile station of a traffic amount. 15. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile station communicates by a radio channel between the base station and the mobile station. A base station apparatus, comprising: a traffic measurement unit; a target reception power setting function calculation unit that determines a function based on an output of the traffic measurement unit; and the target reception power setting calculated by the target reception power setting function calculation unit. A base station apparatus comprising: setting function information notifying means for notifying the mobile station of parameter information specifying a function. 16. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile station is used in a mobile communication system for performing communication by a radio channel between the base station and the mobile station. A target reception power value receiving means for receiving target reception power information, and selecting a target reception power value corresponding to an attribute of the mobile station from the received target reception power information; A transmission unit for calculating a transmission power value of the transmission signal based on the power value. 17. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile station is used in a mobile communication system for performing communication by a radio channel between the base station and the mobile station. A mobile station apparatus that receives traffic amount information and calculates a target received power value based on an attribute of the own station and the traffic amount information; and a target received power value based on the target received power value. A mobile station device comprising: a transmission unit that calculates a transmission power value of a transmission signal. 18. A mobile communication system comprising a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile station communicates by a radio channel between the base station and the mobile station. A setting function information receiving means for receiving parameter information for specifying the target reception power setting function; reconstructing a target reception power setting function from the received parameter information; A target reception power value generation unit that determines a target reception power value from the target reception power setting function based on the target reception power setting function; and a transmission unit that calculates a transmission power value of a transmission signal based on the target reception power value. Mobile station device. 19. A mobile communication system configured by a base station and a plurality of mobile stations existing in a communication area of the base station, wherein the mobile communication system performs communication by a radio channel between the base station and the mobile station. A first step of measuring a traffic amount of the radio channel; and a second step of calculating a target reception power value of a signal received by the base station based on the measured traffic amount and an attribute of the mobile station. And a third step in which the mobile station calculates a transmission power value based on the target reception power value and transmits a signal at the transmission power value.