JP2004260446A - Mobile communication system, radio control apparatus, base station, and method for controlling transmission power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication system capable of appropriately determining the reference value of transmission power at a downlink channel in power balance control, and to provide a radio control apparatus, a base station, and a method for controlling transmission power. <P>SOLUTION: Each base station 10 in which a channel is set at a portion to a mobile station 50 during soft handover informs the radio control apparatus 30 of a transmission power value at the downlink channel toward the mobile station 50 from an own station. The radio control apparatus 30 determines a cell 20 whose communication quality is best in cells 20 provided by each base station 10 in which the channel is set at the portion to the mobile station 50 during soft handover, decides the transmission power value at the downlink channel in the base station 10 providing the cell 20 as the reference value for reporting to each base station 10. Each base station 10 controls the transmission power value at the downlink channel toward the mobile station 50 during the soft handover from the own station so that the transmission power value approaches the informed reference value. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile communication system having a plurality of base stations and a radio control device for controlling each of the base stations, and more particularly to a mobile communication system capable of controlling downlink transmission power from a base station to a mobile station. The present invention relates to a communication system.
[0002]
[Prior art]
In a mobile communication system that employs CDMA (Code Division Multiple Access) and is capable of so-called soft handover, a mobile station can communicate with a plurality of base stations at the time of handover.
[0003]
In general, in mobile communication, a radio channel set between a base station and a mobile station constantly fluctuates due to fading. In order to suppress the effect of such fading, the mobile station during soft handover sends a downlink (from the base station to the mobile station) to a plurality of base stations that have established a line with the mobile station. A command (downlink transmission power control command, for example, TPC bit) for controlling the transmission power of the line is transmitted. In response to the downlink transmission power control command, the base station increases or decreases the downlink transmission power and performs power balance control for the purpose of balancing the downlink transmission power.
[0004]
On the other hand, the base station controls the transmission power of the uplink (the line from the mobile station to the base station) to the mobile station that has established a channel with itself (an uplink transmission power control command). Send The mobile station increases or decreases the downlink transmission power according to the uplink transmission power control command.
[0005]
When the closed loop transmission power control is performed, the mobile station during soft handover issues a downlink transmission power control command with the same transmission power to a plurality of base stations that have set up a line with the mobile station. Send. For this reason, the base station can correctly receive the downlink transmission power control command when the propagation loss on the uplink from the mobile station to the base station is small, but when the propagation loss on the uplink is large, May fail to receive the downlink transmission power control command. As a result, the transmission power of each downlink set between each of the plurality of base stations and the mobile station may become uneven.
[0006]
In this way, consider a case where the transmission power of each downlink set between each of the plurality of base stations and the mobile station becomes non-uniform. For example, the transmission power of the downlink in the base station which failed to receive the downlink transmission power control command from the mobile station due to the large propagation loss of the uplink is reduced by the transmission of the downlink in the base station with the smallest propagation loss in the uplink. Consider the case where the power becomes smaller than the electric power. In this case, the mobile station is likely to fail to receive the uplink transmission power control command transmitted by the base station having a large uplink propagation loss. However, the transmission power of the uplink is not so problematic because it is mainly controlled by an uplink control command from a base station having a small propagation loss.
[0007]
On the other hand, the transmission power of the downlink in the base station that failed to receive the downlink transmission power control command from the mobile station due to the large propagation loss of the uplink is reduced by the transmission of the downlink in the base station with the smallest propagation loss in the uplink. Consider the case where the power becomes larger than the electric power. In this case, because the propagation loss in the uplink is large, the transmission power of the downlink in the base station that fails to receive the downlink transmission power control command from the mobile station is unnecessarily increased, and the other transmission power in the cell provided by the base station is increased. May interfere with the mobile station, and as a result, the downlink channel capacity may decrease.
[0008]
In order to solve such a problem, for example, in Patent Document 1 (Japanese Patent Laid-Open Publication No. H11-340910), every time a base station receives a downlink transmission power control command, the transmission power of the downlink is controlled according to the control command. And controlling the downlink transmission power value so as to approach a predetermined reference value. In Patent Document 1, as the reference value, the maximum transmission power at the base station, the minimum transmission power, an intermediate value between the decibel value of the maximum transmission power and the decibel value of the minimum transmission power, and the statistical value of the transmission power at the base station are used. I have.
[0009]
Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-232353), base stations are divided into a group having good downlink communication quality and a group having deteriorated downlink communication, and base stations belonging to a group having good downlink communication quality. The power balance control is continued, and the base station of the group in which the communication quality of the downlink is degraded is caused to perform control to reduce the transmission power of the downlink to a predetermined level, so that the communication quality is reduced. There is disclosed a method for reducing interference given to a good downlink and increasing the downlink channel capacity.
[0010]
[Patent Document 1]
JP-A-11-340910 (pages 11-12, FIG. 6)
[0011]
[Patent Document 2]
JP-A-2002-232353 (pages 10 to 12, FIG. 7)
[0012]
[Problems to be solved by the invention]
However, Patent Document 1 described above does not consider that the communication quality of the downlink in each base station differs. For this reason, for example, if the base station has set the transmission power value of the downlink to a large value because the communication quality of the downlink has deteriorated, if the transmission power value is determined as a reference value, In this case, the transmission power of the downlink in the base station becomes unnecessarily large, and waste occurs.
[0013]
Further, in Patent Document 2 described above, it is possible to reduce interference given to a downlink with good communication quality and increase the downlink channel capacity. There is no description from the viewpoint of how to decide.
[0014]
Therefore, an object of the present application is to provide a mobile communication system, a radio control apparatus, a base station, and a transmission power control method capable of appropriately determining a reference value of downlink transmission power in power balance control.
[0015]
[Means for Solving the Problems]
In order to solve the above problem, the present invention provides a mobile communication system including a plurality of base stations and a radio control device that controls each of the base stations, as described in claim 1. A transmission power value notifying unit for notifying the radio control device of a transmission power value of a downlink from the own station to the mobile station, wherein the radio control device has a communication quality among cells provided by each of the base stations. Cell determination means for determining a good cell, reference value determination means for determining a downlink transmission power value in a base station providing a cell determined by the cell determination means as a reference value, the reference value Reference value notifying means for notifying the base station, and each of the base stations includes a transmission power control means for controlling a transmission power value of a downlink from its own station to the mobile station so as to approach the reference value. .
[0016]
Also, according to the present invention, in a radio control apparatus for controlling a plurality of base stations constituting a mobile communication system, the radio control apparatus is notified from each of the base stations and travels from the base station to a mobile station. Transmission power value acquisition means for acquiring a downlink transmission power value, a cell determination means for determining a cell having good communication quality among cells provided by each of the base stations, and a cell determined by the cell determination means Reference value determining means for determining a downlink transmission power value at a base station providing a base station as a reference value of a downlink transmission power value at each base station, and a reference value for notifying the reference value to each of the base stations. Notification means.
[0017]
According to a third aspect of the present invention, in the wireless control apparatus according to the second aspect, the communication quality is an uplink communication quality from the mobile station to the base station.
[0018]
According to a fourth aspect of the present invention, in the wireless control apparatus according to the third aspect, there is provided an uplink communication quality measuring means for measuring the uplink communication quality.
[0019]
According to a fifth aspect of the present invention, in the wireless control apparatus according to the second aspect, the communication quality is the downlink communication quality.
[0020]
Further, according to the present invention, in a base station constituting a mobile communication system together with another base station, a transmission power value of a downlink from the own station to the mobile station is determined by the mobile communication system. A transmission power value notifying unit that notifies a radio control apparatus that controls each of the constituent base stations, and a cell with good communication quality among the base stations that configure the mobile communication system, which is notified from the radio control apparatus. A transmission power value of the downlink in the providing base station, a reference value acquisition means for acquiring as a reference value of the transmission power value of the downlink, and a transmission power value of the downlink from the own station to the mobile station, the reference value And transmission power control means for performing control so as to approach the threshold value.
[0021]
Further, according to the present invention, as set forth in claim 7, in the base station according to claim 6, a downlink communication quality acquisition unit that acquires the downlink communication quality notified from the mobile station, Downlink communication quality notifying means for notifying the wireless control device of downlink communication quality.
[0022]
Further, according to the present invention, in a mobile communication system having a plurality of base stations and a radio control device for controlling the base stations, a transmission for controlling transmission power of each of the base stations is provided. In the power control method, each of the base stations notifies the radio control apparatus of a transmission power value of a downlink from the own station to the mobile station, and the radio control apparatus includes, among cells provided by the base stations, Determine a cell with good communication quality, the radio control apparatus determines the transmission power value of the downlink in the base station that provides the cell with good communication quality as a reference value, and the radio control apparatus determines The base station notifies the base station of the reference value, and the base station controls the transmission power value of the downlink from its own station to the mobile station so as to approach the reference value.
[0023]
According to the present invention, the radio control apparatus notifies a downlink transmission power value at a base station that provides a cell with good communication quality as a reference value of a downlink transmission power value at each base station, and The station controls the transmission power value of the downlink from its own station to the mobile station so as to approach this reference value. The transmission power value of the downlink in the base station that provides a cell with good communication quality is generally a small value. Therefore, since the reference value of the transmission power in the power balance control is determined to be the transmission power value of the downlink in the base station that provides a cell with good communication quality, the transmission power of the downlink in each base station is wasted. It is possible to prevent the transmission power from becoming large and to set appropriate downlink transmission power in each base station.
[0024]
Further, when the communication quality for determining the reference value is the downlink communication quality, the radio control apparatus transmits downlink data at each base station even when the uplink and downlink communication qualities are significantly different. The reference value of the power value can be appropriately determined.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 is a diagram illustrating a configuration example of a mobile communication system according to an embodiment of the present invention. The mobile communication system 1 shown in FIG. 1 employs CDMA and is capable of so-called soft handover, and includes base stations 10-1, 10-2 and 10-3 (hereinafter, these base stations 10-1, 10- 2 and 10-3 are collectively referred to as “base station 10” as appropriate, a radio controller 30 that controls these base stations 10, and mobile stations 50-1, 50-2, and 50-3 (hereinafter, referred to as “base station 10”). The mobile stations 50-1, 50-2, and 50-3 are collectively referred to as "mobile station 50" as appropriate.
[0027]
In FIG. 1, base stations 10-1, 10-2, and 10-3 include cells 20-1, 20-2, and 20-3 as radio zones (hereinafter, these cells 20-1, 20-2, and 20-). 3 are collectively referred to as a “cell 20”). The mobile station 50-1 existing in the area where the cell 20-1 and the cell 20-2 overlap is performing soft handover, and provides the base station 10-1 and the cell 20-2 that provide the cell 20-1. Communication is possible with both of the base stations 20-2.
[0028]
In the mobile communication system 1, the transmission power value of the downlink from each base station 10 whose channel is set to the mobile station 50 during soft handover to the mobile station 50 during soft handover approaches the reference value. The power balance control is performed as described above. Hereinafter, first and second embodiments of the details of the power balance control in the mobile communication system 1 will be described.
(First embodiment)
In the first embodiment, the communication quality of the uplink is used at the time of power balance control in the mobile communication system 1.
[0029]
FIG. 2 is a diagram illustrating a configuration example of the base station 10 according to the first embodiment. The base station 10 shown in FIG. 1 includes an antenna 11, a mobile station signal receiving section 12, a radio control apparatus signal transmitting section 13, a radio control apparatus signal receiving section 14, a downlink transmission power control section 15, and a mobile station signal transmitting section 16. .
[0030]
FIG. 3 is a diagram illustrating a configuration example of the wireless control device 30 according to the first embodiment. The radio controller 30 shown in FIG. 1 includes a base station signal receiving unit 31, an uplink communication quality measuring unit 32, a main cell determining unit 33, a reference value determining unit 34, and a base station signal transmitting unit 35.
[0031]
First, a description will be given with reference to FIG. The mobile station signal receiving unit 12 in the base station 10 in which a line is set up with the mobile station 50 during soft handover receives a user signal from the mobile station 50 via the antenna 11. Further, mobile station signal receiving section 12 outputs the received user signal to radio control apparatus signal transmitting section 13.
[0032]
The wireless control device signal transmitting unit 13 transmits the input user signal to the wireless control device 30 after including the identification information (cell identification information) of the cell 20 provided by the own station. Further, the radio control apparatus signal transmission unit 13 acquires the downlink transmission power value (hereinafter, referred to as “downlink transmission power value”) set by the downlink transmission power control unit 15 at that time, and After the identification information (cell identification information) of the cell 20 to be provided is included, the information is transmitted to the wireless control device 30.
[0033]
Next, a description will be given with reference to FIG. The base station signal receiving unit 31 in the radio control apparatus 30 receives a user signal and a downlink transmission power value transmitted from each base station 10 whose channel is set up with the mobile station 50 during soft handover. Further, the base station signal receiving section 31 outputs the user signal to the uplink communication quality measuring section 32 and an exchange (not shown), and outputs the downlink transmission power value to the reference value determining section 34.
[0034]
The uplink communication quality measurement unit 32 performs uplink communication from the mobile station 50 during soft handover to each base station 10 for which a line is set up with the mobile station 50 based on the input user signals. Quality (hereinafter referred to as “uplink communication quality”) is measured. Here, the uplink communication quality may be an arbitrary parameter, such as a reception level of a common pilot channel, a reception SNIR, and a block error rate. The uplink communication quality measurement unit 32 associates each measured uplink communication quality with the cell identification information included in the user signal corresponding to the uplink communication quality, and outputs the result to the main cell determination unit 33.
[0035]
The main cell determination unit 33 determines, as the main cell, the cell 20 having the best uplink communication quality among the cells 20 provided by each base station 10 whose channel is set up with the mobile station 50 during soft handover. . Specifically, the main cell determination unit 33 specifies the best uplink communication quality from among the uplink communication qualities from the uplink communication quality measurement unit 32. Next, the main cell determination unit 33 determines the cell 20 provided by the base station 10 corresponding to the best uplink communication quality as a main cell. Further, the main cell determination unit 33 outputs the identification information of the cell associated with the best uplink communication quality, that is, the cell identification information of the main cell, to the reference value determination unit 34.
[0036]
The reference value determination unit 34 determines, as a reference value, the downlink transmission power value at the base station 10 that provides the main cell from among the downlink transmission power values from the base station signal receiving unit 31. Specifically, reference value determining section 34 extracts cell identification information from each downlink transmission power value from base station signal receiving section 31. Next, the reference value determination unit 34 specifies, from the extracted cell identification information, the one that matches the cell identification information from the main cell determination unit 33. Further, the reference value determination unit 34 determines a downlink transmission power value including the specified cell identification information as a reference value. The determined reference value is output to base station signal transmitting section 35.
[0037]
The base station signal transmission unit 35 transmits the reference value from the reference value determination unit 34 to each base station 10 for which a line is set with the mobile station 50 during soft handover. Further, when there is a user signal addressed to the mobile station 50 during soft handover, the base station signal transmission unit 35 transmits this user signal to each base station with a line set up with the mobile station 50 during soft handover. Transmit to station 10.
[0038]
Description will be made again with reference to FIG. The radio control apparatus signal receiving unit 14 in the base station 10 in which a line is set up with the mobile station 50 during the soft handover receives the reference value transmitted from the radio control apparatus 30 and transmits the downlink transmission power control unit. 15 is output. In addition, when the wireless control device 30 has transmitted a user signal, the wireless control device signal receiving unit 14 receives the user signal and outputs the user signal to the mobile station signal transmitting unit 16.
[0039]
The downlink transmission power control unit 15 sets the downlink transmission power value so as to approach the input reference value. The mobile station signal transmitting unit 16 transmits a user signal or the like to the mobile station 50 during soft handover in which a line is set between itself and the own station, using the downlink transmission power value set by the downlink transmission power control unit 15. I do.
[0040]
Next, the operation of the mobile communication system 1 according to the first embodiment will be described. FIG. 4 is a sequence diagram illustrating an operation of the mobile communication system 1 according to the first embodiment. When receiving a user signal transmitted from the mobile station 50 (step 101), the base station 10 having a line set up with the mobile station 50 during soft handover receives the user signal and the cell provided by the own station. And the downlink transmission power value at that time are transmitted to the radio network controller 30 (step 102).
[0041]
The radio controller 30 measures the communication quality based on the user signal transmitted from each base station 10 whose line is set up with the mobile station 50 during the soft handover (step 103). Further, based on the measured uplink communication qualities, the radio control apparatus 30 selects, among the cells 20 provided by the respective base stations 10 whose channels are set up with the mobile station 50 during the soft handover, the uplink communication quality. Determines the best cell 20 as the main cell (step 104).
[0042]
Next, radio control apparatus 30 determines, as a reference value, the downlink transmission power value at base station 10 that provides the main cell from among the received downlink transmission power values (step 105). Further, the radio controller 30 transmits the determined reference value and the user signal to each base station 10 in which a line is set up with the mobile station 50 during the soft handover (step 106).
[0043]
The base station 10 whose line is set up with the mobile station 50 during the soft handover sets the downlink transmission power value so as to approach the received reference value (step 107). Further, the base station 10 in which a line is set up with the mobile station 50 during soft handover transmits a user signal or the like to the mobile station 50 during soft handover at the set downlink transmission power value (step 108). .
[0044]
In the first embodiment, the uplink communication quality measuring unit 32 in the radio network controller 30 measures the uplink communication quality, but the base station 10 may measure the uplink communication quality. In this case, a configuration in which an uplink communication quality measuring unit is provided between the mobile signal receiving unit 12 and the wireless control device signal transmitting unit 13 in the base station 10 instead of the uplink communication quality measuring unit 32 in the wireless control device 30 And Then, the radio control device signal transmitting unit 13 in the base station 10 measures the uplink communication quality measured by the uplink communication quality measuring unit to the radio control device 30. The base station signal receiving unit 31 in the wireless control device 30 outputs the uplink communication quality from the base station 10 to the main cell determination unit 33, and the main cell determination unit 33 Is determined.
(Second embodiment)
In the second embodiment, at the time of power balance control in the mobile communication system 1, downlink communication quality is used.
[0045]
The configuration of the base station 10 in the second embodiment is the same as the configuration of the base station 10 in the first embodiment shown in FIG. That is, the base station 10 in the second embodiment includes an antenna 11, a mobile station signal receiver 12, a radio controller signal transmitter 13, a radio controller signal receiver 14, a downlink transmission power controller 15, and a mobile station signal transmitter. 16 is provided. Hereinafter, the base station 10 in the second embodiment will be described with reference to FIG.
[0046]
On the other hand, the configuration of the wireless control device 30 in the second embodiment is different from the configuration of the wireless control device 30 in the first embodiment shown in FIG. FIG. 5 is a diagram illustrating a configuration example of the wireless control device 30 according to the second embodiment. The radio control apparatus 30 shown in FIG. 1 includes a base station signal receiving unit 31, a main cell determining unit 33, a reference value determining unit 34, and a base station signal transmitting unit 35.
[0047]
First, a description will be given with reference to FIG. The mobile station signal receiving unit 12 in the base station 10 in which the line is set up with the mobile station 50 during the soft handover transmits the user signal from the mobile station 50 to the antenna 11 as in the first embodiment. To receive through. Further, the mobile station signal receiving unit 12 receives, via the antenna 11, the downlink communication quality measured by the mobile station 10 during the soft handover. Further, the mobile station signal receiving section 12 outputs the received user signal and downlink communication quality to the radio control apparatus signal transmitting section 13.
[0048]
The wireless control device signal transmission unit 13 transmits the input user signal to the wireless control device 30. Further, the radio control apparatus signal transmission unit 13 transmits the input downlink communication quality to the radio control apparatus 30 after including the identification information (cell identification information) of the cell 20 provided by the own station. Further, the radio control apparatus signal transmission unit 13 acquires the downlink transmission power value (hereinafter, referred to as “downlink transmission power value”) set by the downlink transmission power control unit 15 at that time, and After the identification information (cell identification information) of the cell 20 to be provided is included, the information is transmitted to the wireless control device 30.
[0049]
Next, a description will be given with reference to FIG. The base station signal receiving unit 31 in the radio control apparatus 30 includes a user signal, a downlink communication quality, and a downlink transmission power value transmitted from each base station 10 whose channel is set up with the mobile station 50 during soft handover. To receive. Further, the base station signal receiving section 31 outputs the user signal to an exchange (not shown). In addition, base station signal receiving section 31 outputs the downlink communication quality to main cell determining section 33 and outputs the downlink transmission power value to reference value determining section 34.
[0050]
The main cell determination unit 33 determines, as the main cell, the cell 20 with the best downlink communication quality among the cells 20 provided by each base station 10 whose line is set up with the mobile station 50 during soft handover. . Specifically, the main cell determination unit 33 specifies the best downlink communication quality from the downlink communication qualities from the base station signal receiving unit 31. Next, the main cell determination unit 33 determines the cell 20 provided by the base station 10 corresponding to the best downlink communication quality as a main cell. Furthermore, the main cell determination unit 33 outputs the identification information of the cell included in the best downlink communication quality, that is, the cell identification information of the main cell, to the reference value determination unit 34.
[0051]
The reference value determination unit 34 determines, as a reference value, the downlink transmission power value at the base station 10 that provides the main cell from among the downlink transmission power values from the base station signal receiving unit 31. The specific determination method is the same as in the first embodiment. That is, the reference value determining unit 34 extracts the cell identification information from each downlink transmission power value from the base station signal receiving unit 31. Next, the reference value determination unit 34 specifies, from the extracted cell identification information, the one that matches the cell identification information from the main cell determination unit 33. Further, the reference value determination unit 34 determines a downlink transmission power value including the specified cell identification information as a reference value. The determined reference value is output to base station signal transmitting section 35.
[0052]
The base station signal transmission unit 35 transmits the reference value from the reference value determination unit 34 to each base station 10 for which a line is set with the mobile station 50 during soft handover. Further, when there is a user signal addressed to the mobile station 50 during soft handover, the base station signal transmitting unit 35 transmits the user signal to the mobile station 50 during soft handover. Transmit to base station 10.
[0053]
Description will be made again with reference to FIG. The base station 10 that has received the reference value and the user signal performs the same processing as in the first embodiment. That is, the radio control apparatus signal receiving unit 14 in the base station 10 in which the line is set up with the mobile station 50 during soft handover receives the reference value transmitted from the radio control apparatus 30 and outputs the downlink transmission power. Output to the control unit 15. In addition, when the wireless control device 30 has transmitted a user signal, the wireless control device signal receiving unit 14 receives the user signal and outputs the user signal to the mobile station signal transmitting unit 16.
[0054]
The downlink transmission power control unit 15 sets the downlink transmission power value so as to approach the input reference value. The mobile station signal transmitting unit 16 transmits a user signal or the like to the mobile station 50 during soft handover in which a line is set between itself and the own station, using the downlink transmission power value set by the downlink transmission power control unit 15. I do.
[0055]
Next, the operation of the mobile communication system 1 according to the second embodiment will be described. FIG. 6 is a sequence diagram illustrating an operation of the mobile communication system 1 according to the second embodiment. Upon receiving the user signal and the downlink communication quality transmitted from the mobile station 50 (step 201), the base station 10 having a line set up with the mobile station 50 during the soft handover receives the user signal and the downlink communication. The quality, the cell identification information of the cell provided by the own station, and the downlink transmission power value at that time are transmitted to the radio network controller 30 (step 202).
[0056]
The radio control device 30 is configured to provide, based on the downlink communication quality transmitted from each base station 10 whose channel is set to the mobile station 50 during soft handover, The cell 20 having the best downlink communication quality is determined as the main cell (step 203).
[0057]
Next, the radio controller 30 determines, as a reference value, the downlink transmission power value at the base station 10 that provides the main cell from among the received downlink transmission power values (step 204). Further, the wireless control device 30 transmits the determined reference value and the user signal to each base station 10 in which a line is set up with the mobile station 50 during soft handover (step 205).
[0058]
The base station 10 in which a line is set up with the mobile station 50 during the soft handover sets the downlink transmission power value so as to approach the received reference value (step 206). Further, the base station 10 having a line set up with the mobile station 50 during soft handover transmits a user signal or the like to the mobile station 50 during soft handover with the set downlink transmission power value (step 207). .
[0059]
As described above, in the mobile communication system 1 according to the present embodiment, each base station 10 whose line is set up with the mobile station 50 during soft handover travels from its own station to the mobile station 50 during soft handover. The transmission power value of the downlink is notified to the radio control apparatus 30. In order to perform power balance control, the radio controller 30 determines a cell having the best communication quality among the cells 20 provided by each base station 10, and determines a cell having the best communication quality in the base station 10 which provides the cell 20 having the best communication quality. The transmission power value of the downlink is determined as a reference value, and is notified to each base station 10 in which the channel is set with the mobile station 50 during soft handover. The base station 10 in which a line is set between the mobile station 50 during soft handover and the base station 10 sets the transmission power value of the downlink from the own station to the mobile station 50 during soft handover so as to approach the reference value. Control.
[0060]
The downlink transmission power value in the base station 10 that provides the cell 20 with the best communication quality is generally small since the influence of fading is small. Therefore, the reference value of the transmission power in the power balance control is determined to be the downlink transmission power value in the base station 10 that provides the cell 20 with the best communication quality, so that the mobile communication system 1 is configured during soft handover. The transmission power of the downlink in each base station 10 to which a line is set up with the mobile station 50 is prevented from being unnecessarily increased despite good communication quality. In this case, it is possible to appropriately set the transmission power of the downlink.
[0061]
In particular, in the second embodiment, downlink communication quality is used as communication quality. When the uplink communication quality is used, in an environment where the uplink communication quality and the downlink communication quality are significantly different, the downlink transmission power value at the base station 10 that provides the cell 20 with the best uplink communication quality is not necessarily the value of each base station. The downlink transmission power value in 10 is not always small. As a result, the reference value determined by the wireless control device 30 may not be an appropriate value. However, in the second embodiment, the radio control apparatus 30 determines the downlink transmission power value in the base station 10 that provides the cell 20 with the best downlink communication quality as a reference value, and thus, the radio communication apparatus 30 The minimum one of the downlink transmission power values of the base stations 10 between which a line is set can be used as the reference value. Therefore, even in an environment where the uplink communication quality and the downlink communication quality are significantly different, a more appropriate setting of the downlink transmission power can be made at each base station 10 in which a line is set up with the mobile station 50 during soft handover. Will be possible.
[0062]
In the above-described embodiment, the radio communication control device 30 determines the transmission power value of the downlink in the base station 10 that provides the cell 20 with the best communication quality as the reference value, but the communication quality is not the best. The transmission power value of the downlink in the base station 10 that provides a predetermined or better cell 20 may be determined as a reference value.
[0063]
【The invention's effect】
According to the present invention, it is possible to appropriately determine a reference value of downlink transmission power in power balance control.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a mobile communication system according to an embodiment.
FIG. 2 is a diagram illustrating a configuration example of a base station in the first and second embodiments.
FIG. 3 is a diagram illustrating a configuration example of a wireless control device according to the first embodiment.
FIG. 4 is a sequence diagram showing an operation of the mobile communication system in the first embodiment.
FIG. 5 is a diagram illustrating a configuration example of a wireless control device according to a second embodiment.
FIG. 6 is a sequence diagram showing an operation of the mobile communication system in the second embodiment.
[Explanation of symbols]
1 mobile communication system
10-1, 10-2, 10-3 base station
11 Antenna
12 Mobile station signal receiver
13 Wireless controller signal transmission unit
14 Radio control unit signal receiving unit
15 Downlink transmission power control unit
16 Mobile station signal transmitter
20-1, 20-2, 20-3 cells
30 wireless control device
31 base station signal receiver
32 Uplink communication quality measurement unit
33 Main cell judgment unit
34 Reference value determination unit
35 base station signal transmitter
50-1, 50-2, 50-3 mobile station

Claims (8)

In a mobile communication system having a plurality of base stations and a radio control device that controls each of the base stations,
Each said base station,
A transmission power value notifying unit that notifies the radio control device of a transmission power value of a downlink from the own station to the mobile station,
The wireless control device,
Among the cells provided by each of the base stations, a cell determination unit that determines a cell having good communication quality,
Reference value determination means for determining the transmission power value of the downlink in the base station providing the cell determined by the cell determination means as a reference value,
Reference value notification means for notifying the reference value to each of the base stations,
With
Each said base station,
A mobile communication system comprising transmission power control means for controlling a downlink transmission power value from the own station to the mobile station so as to approach the reference value. In a wireless control device that controls a plurality of base stations constituting a mobile communication system,
A transmission power value acquisition unit that is notified from each of the base stations and acquires a transmission power value of a downlink from the base station to the mobile station,
Among the cells provided by each of the base stations, a cell determination unit that determines a cell having good communication quality,
Reference value determination means for determining a downlink transmission power value in a base station providing a cell determined by the cell determination means as a reference value of a downlink transmission power value in each base station,
Reference value notification means for notifying the reference value to each of the base stations,
A wireless control device comprising: The wireless control device according to claim 2,
The radio control apparatus according to claim 1, wherein the communication quality is an uplink communication quality from the mobile station to the base station. The wireless control device according to claim 3,
A wireless control device comprising an uplink communication quality measuring means for measuring the uplink communication quality. The wireless control device according to claim 2,
The wireless control device, wherein the communication quality is the downlink communication quality. In a base station constituting a mobile communication system together with other base stations,
Transmission power value notifying means for notifying the transmission power value of the downlink from the own station to the mobile station to a radio control device controlling each base station constituting the mobile communication system,
Notified by the radio control apparatus, among the base stations constituting the mobile communication system, the transmission power value of the downlink in the base station that provides a cell with good communication quality, a reference for the transmission power value of the downlink. Reference value acquisition means for acquiring as a value,
Transmission power control means for controlling the downlink transmission power value from the own station to the mobile station so as to approach the reference value,
A base station comprising: In the base station according to claim 6,
Downlink communication quality acquiring means for acquiring the downlink communication quality notified from the mobile station,
Downlink communication quality notifying means for notifying the radio control device of the downlink communication quality,
A base station comprising: In a mobile communication system having a plurality of base stations and a radio control device that controls the base station, in a transmission power control method of controlling the transmission power of each base station,
Each of the base stations notifies the radio control apparatus of a transmission power value of a downlink from the own station toward the mobile station,
The wireless control device, among the cells provided by each of the base stations, determines a cell with good communication quality,
The wireless control device determines the transmission power value of the downlink in the base station that provides a cell with good communication quality as a reference value,
The wireless control device notifies the determined reference value to each of the base stations,
A transmission power control method, wherein each of the base stations controls a transmission power value of a downlink from its own station to the mobile station so as to approach the reference value.

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