JP2003348010A - Control device, mobile communication system, and transmission power control method - Google Patents

Abstract

(57) [Problem] To provide a control device capable of performing appropriate transmission power control at the start of communication. SOLUTION: A control device 30 according to the present invention is a control device 30 that wirelessly controls communication between a radio terminal 10 and a base station 20, and starts communication between the base station 20 and the radio terminal 10. When the communication type is determined, the communication type determining unit 34 that determines the communication type and the transmission power setting unit 32 that determines the initial value of the transmission power based on the determination result by the communication type determining unit 34 are provided. The transmission power setting means 32 sets the set value of the transmission power higher than the reference value when the communication type is voice communication, and sets the set value of the transmission power lower than the reference value when the communication type is data communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device, a mobile communication system, and a transmission power control method capable of setting transmission power at the start of communication.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication system, transmission power is controlled in data transmission from a base station to a radio terminal. FIG. 18 shows a conventional transmission power control method. First, when a wireless terminal receives a control signal transmitted from a base station, the received power is measured. Next, the wireless terminal transmits information on the measured received power to the control device through the base station. Then, the control device sets the transmission power so as to maintain the predetermined reception quality, and instructs the base station.

[0003]

In the conventional transmission power control method, the setting of the transmission power based on the reception power in the radio terminal is performed at intervals of several ms during the communication between the radio terminal and the base station. The transmission power of the station is properly controlled. However, when communication with a new base station is started due to handover or the like, the time at which data is transmitted from the new base station is slightly different from the time at which information on the received power that is the basis of transmission power setting is obtained. Therefore, if there is a change in the signal interference situation in the wireless terminal within that time, the transmission power may not be able to be appropriately controlled. If the transmission power is higher than the required power, other communication multiplexed on the same channel or other cells may interfere with a channel of the same frequency in another cell, causing radio quality degradation, and the transmission power may be lower than the required power. In such a case, there has been a problem that the communication quality is deteriorated until the transmission power is stabilized. In particular, IMT-
In 2000 / TDD, the power operation range by the transmission power control is 3 dB / 10 ms at the maximum, and if the initial value of the transmission power is different from the required power, the time for controlling the transmission power to the required power becomes longer. It was desired to solve this problem.

[0004] Therefore, an object of the present invention is to solve the above problems and to provide a control device, a mobile communication system, and a transmission power control method capable of performing appropriate transmission power control at the start of communication.

[0005]

A control device according to the present invention is a control device for wirelessly controlling communication between a wireless terminal and a base station, and starts communication between the base station and the wireless terminal. In this case, there is provided a communication type determining unit for determining the communication type, and a transmission power setting unit for determining an initial value of the transmission power based on a determination result by the communication type determining unit.

A transmission power control method according to the present invention is a transmission power control method for controlling the transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, A communication type determining step of determining a communication type when starting communication between the base station and the wireless terminal; and a transmission power setting step of determining an initial value of transmission power based on a determination result in the communication type determining step. And the following.

In the control device (transmission power control method) according to the present invention, an initial value of the transmission power is determined based on the communication type determined by the communication type determining means (in the communication type determining step). The initial value of the transmission power can be easily and appropriately set according to the type. That is, the transmission power set according to the communication type in which signal retransmission is allowed and the communication type in which signal retransmission is not allowed is changed, thereby improving the communication quality while reducing interference as a whole.

In the above control device (transmission power control method), the communication type determination means (step) determines whether the communication type is voice communication or data communication, and the transmission power setting means (step) When the type is voice communication, the initial value of the transmission power is set higher than a predetermined reference value, and when the communication type is data communication, the initial value of the transmission power is lower than the predetermined reference value. May be set.

When the communication type is voice communication, it is necessary to continuously receive a signal to maintain a predetermined communication quality, and it is not preferable to retransmit the signal. In the case of data communication, even if there is some data loss due to quality degradation, quality degradation can be compensated for by retransmission control by an upper layer such as TCP / IP. Therefore, if the communication type is voice communication, setting the initial value of the transmission power higher than the reference value will lower the communication quality due to insufficient transmission power even if the correct reception power at the wireless terminal cannot be grasped at the start of communication. And reduce the interference by setting the transmission power lower than the reference value when the communication type is data communication, thereby suppressing an increase in the total transmission power including voice communication and data communication. Can be done.

A control device according to the present invention is a control device for wirelessly controlling communication between a wireless terminal and a base station. When starting communication between the base station and the wireless terminal, the communication is performed. Communication type determining means for determining a communication type of another communication multiplexed on the allocated channel; and transmission power setting means for determining an initial value of transmission power based on a determination result by the communication type determining means. Features.

[0011] A transmission power control method according to the present invention is a transmission power control method for controlling the transmission power of a base station at the start of communication by a controller that wirelessly controls communication between a wireless terminal and a base station, When starting communication between a base station and a wireless terminal, a communication type determining step of determining a communication type of another communication multiplexed on a channel to which the communication is allocated, and a communication type determining step. A transmission power setting step of determining an initial value of the transmission power using the transmission power setting.

In the control device (transmission power control method) according to the present invention, the transmission power is determined based on the communication type of another communication multiplexed on the same channel determined by the communication type determining means (in the communication type determining step). Is determined, the initial value of the transmission power can be easily and appropriately set according to the communication type of the other communication. That is, the transmission power set according to the communication type in which signal retransmission is allowed and the communication type in which signal retransmission is not allowed is changed, thereby improving the communication quality while reducing interference as a whole.

In the above control device (transmission power control method), the communication type determining means (step) determines whether the communication type of the other communication is voice communication or data communication,
The transmission power setting means (step) sets an initial value of the transmission power to be lower than a predetermined reference value when at least one communication type is voice communication, and sets the initial value of the transmission power to data communication when all communication types are data communication. May set an initial value of transmission power higher than a predetermined reference value.

When the communication type is voice communication, it is necessary to continuously receive signals in order to maintain a predetermined communication quality, and it is not preferable to retransmit a signal. In the case of data communication, even if there is some data loss due to quality degradation, quality degradation can be compensated for by retransmission control by an upper layer such as TCP / IP. Therefore, when at least one communication type of the other multiplexed communication is voice communication, the transmission power of the voice communication is set to be high in order to maintain high communication quality. By setting the transmission power higher than the reference value by reducing the interference with the voice communication multiplexed at a low setting and by setting the transmission power higher than the reference value when the communication type of all other communication is data communication, the interference is reduced and the High quality communication can be realized.

A control device according to the present invention is a control device for wirelessly controlling communication between a wireless terminal and a base station. When starting communication between the base station and the wireless terminal, the communication is performed. A communication type determining unit that determines a communication type of another communication multiplexed on a channel of another cell having the same frequency as the allocated channel, and an initial value of transmission power is determined based on a determination result by the communication type determining unit Transmission power setting means.

A transmission power control method according to the present invention is a transmission power control method for controlling the transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, A communication type determining step of determining a communication type of another communication multiplexed on a channel of another cell having the same frequency as a channel to which the communication is allocated when starting communication between the base station and the wireless terminal; A transmission power setting step of determining an initial value of transmission power based on a determination result in the communication type determination step,
It is characterized by having.

In the control apparatus (transmission power control method) according to the present invention, the initial value of the transmission power is set based on the communication type of another communication multiplexed on the channel of another cell having the same frequency as the assigned channel. By deciding, it is possible to easily and appropriately set the initial value of the transmission power according to the communication type of the communication multiplexed on the channel of another cell. That is, the transmission power set according to the communication type in which signal retransmission is allowed and the communication type in which signal retransmission is not allowed is changed, thereby improving the communication quality while reducing interference as a whole.

In the above control device (transmission power control method), the communication type determining means (step) determines whether the communication type of the other communication is voice communication or data communication,
The transmission power setting means sets an initial value of transmission power lower than a predetermined reference value when at least one communication type is voice communication, and sets the transmission power when all communication types are data communication. May be set higher than a predetermined reference value.

When the communication type is voice communication, it is necessary to continuously receive signals in order to maintain a predetermined communication quality, and it is not preferable to retransmit a signal. In the case of data communication, even if there is some data loss due to quality degradation, quality degradation can be compensated for by retransmission control by an upper layer such as TCP / IP. Also, even in communication with another cell, interference may occur if channels of the same frequency are used at the same time. Therefore, when at least one communication type of another communication multiplexed on a channel of another cell having the same frequency as the allocated channel is voice communication, the transmission power is high to maintain high communication quality of the voice communication. Since the transmission power is set, the initial value of the transmission power is set lower than the reference value to reduce interference with other communication (voice communication), and the communication type of all the communication multiplexed on the channel of the other cell is the data communication type. In this case, by setting the transmission power higher than the reference value, it is possible to reduce interference and realize high-quality communication.

The control apparatus (transmission power control method) according to the present invention includes a channel allocating means (step) for allocating a communication started between a radio terminal and a base station to a channel where no other multiplexed communication exists. In addition, the transmission power setting means (step) sets an initial value of transmission power of communication to which a channel is allocated by the channel allocation means to be higher than a predetermined reference value.

When the channel allocating means (in the channel allocating step) is able to allocate to a channel where no other multiplexed communication exists, it is not necessary to set the transmission power high because no interference problem occurs. It is suitable for improving the quality.

The above-mentioned control device (transmission power control method) comprises a channel allocating means (step) for allocating a communication started between a radio terminal and a base station to a channel whose communication type of communication to be multiplexed is data communication. ), And the transmission power setting means (step) may set the initial value of the transmission power of the communication to which the channel is allocated by the channel allocation means to be higher than a predetermined reference value.

If the channel allocating means (in the channel allocating step) can allocate to the channel whose other multiplexed communication is data communication, the data communication is allowed to be retransmitted, so that the communication is performed with low transmission power. Since it is possible, the transmission power can be set high.

A control device according to the present invention is a control device for wirelessly controlling communication between a wireless terminal and a base station, and determines a reason for the handover when performing handover between a plurality of base stations. And a transmission power setting unit that determines an initial value of the transmission power based on a result of the determination by the reason determination unit.

A transmission power control method according to the present invention is a transmission power control method for controlling the transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, When handing over communication between a plurality of base stations, a reason determining step of determining a reason for the handover and a transmission power setting step of determining an initial value of transmission power based on a determination result in the reason determining step are provided. It is characterized by the following.

In the control device (transmission power control method) according to the present invention, the initial value of the transmission power is determined based on the reason for the handover determined by the reason determination means (at the reason determination step), thereby enabling the handover of the handover. The initial value of the transmission power can be easily and appropriately set according to the reason.

In the above control device (transmission power control method), the reason determination means (step) determines whether the handover is performed for deterioration of radio quality or traffic distribution, and sets the transmission power. The means (step) sets an initial value of the transmission power to be higher than a predetermined reference value when the handover is performed due to the deterioration of the radio quality, and sets the transmission power of the transmission power when the handover is performed for the traffic distribution. It may be characterized in that the initial value is set lower than a predetermined reference value.

If the reason for the handover is the deterioration of the communication quality, it is necessary to improve the communication quality. On the other hand, if the reason for the handover is the traffic distribution, the communication quality is not deteriorated. Absent. Therefore, if the reason for the handover is deterioration of communication quality, the initial value of the transmission power is set higher than the reference value, and if the reason for the handover is traffic distribution, the initial value of the transmission power is set lower than the reference value. By doing so, it is possible to realize high-quality communication while reducing interference.

A control device according to the present invention is a control device for wirelessly controlling communication between a wireless terminal and a base station, and performs handover between two base stations when performing communication handover between the two base stations. It is characterized by comprising base station interval determining means for obtaining an interval, and transmission power setting means for determining an initial value of transmission power based on the base station interval determined by the base station interval determining means.

[0030] A transmission power control method according to the present invention is a transmission power control method for controlling the transmission power of a base station at the start of communication by a control device that wirelessly controls communication between a radio terminal and a base station, When handing over communication between two base stations, a base station interval determining step for determining an interval between the two base stations, and an initial value of transmission power based on the base station interval determined in the base station interval determining step And a transmission power setting step of determining the transmission power.

In the control apparatus (transmission power control method) according to the present invention, the handover determined by the base station interval determining means (in the base station interval determining step) is performed.
By determining the initial value of the transmission power based on the interval between the base stations, the initial value of the transmission power can be easily and appropriately set according to the interval between the base stations.

In the above control apparatus (transmission power control method), the transmission power setting means (step) transmits the signal when the base station interval obtained in the base station interval determination means (step) is larger than a predetermined threshold. The power initial value is set higher than a predetermined reference value, and if the base station interval is smaller than a predetermined threshold, the transmission power initial value is set lower than the predetermined reference value, It is good.

When the interval between the handover source base station and the handover destination base station is large, it is predicted that the interval between the wireless terminal and the handover destination base station is large, and the handover source base station and the handover destination base station are assumed to be large. When the interval between the stations is small, it is expected that the interval between the wireless terminal and the base station of the handover destination is small. Therefore, when the interval between the two base stations is large, the initial value of the transmission power is set high,
When the interval between the two base stations is small, by setting the initial value of the transmission power low, it is possible to realize high-quality communication while reducing interference.

A control device according to the present invention is a control device for wirelessly controlling communication between a wireless terminal and a base station, and performs handover between a plurality of base stations and a handover destination base station. Distance measuring means for determining the distance to the wireless terminal, and transmission power setting means for determining an initial value of the transmission power based on the distance between the base station and the wireless terminal determined by the distance measuring means, characterized by comprising I do.

[0035] A transmission power control method according to the present invention is a transmission power control method for controlling the transmission power of a base station at the start of communication by a control device that wirelessly controls communication between a wireless terminal and a base station, When performing communication handover between a plurality of base stations, a distance measurement step for determining a distance between the handover destination base station and the wireless terminal, and transmission based on a distance between the base station and the wireless terminal determined in the distance measurement step A transmission power setting step of determining an initial value of power.

In the control device (transmission power control method) according to the present invention, the initial value of the transmission power is determined based on the distance between the handover destination base station and the radio terminal measured by the distance measuring means (at the distance measuring step). Is determined, the initial value of the transmission power can be easily and appropriately set according to the distance between the base station and the wireless terminal.

[0037] In the above control device (transmission power control method), the transmission power setting means (step) is configured to transmit the transmission power if the distance measured by the distance measuring means (in the distance measuring step) is larger than a predetermined threshold. The initial value of is set higher than a predetermined reference value, and if the base station interval is smaller than a predetermined threshold, the initial value of the transmission power is set lower than the predetermined reference value, Is also good.

When the distance between the base station at the handover destination and the radio terminal is large, the signal transmitted from the base station generally has a large propagation loss until it reaches the radio terminal. This is set high to prevent the communication quality from deteriorating, and when the distance between the handover destination base station and the wireless terminal is small, sufficient communication quality can be maintained even when transmitting at low transmission power. The power is set low to reduce interference with other communications.

In the above control apparatus (transmission power control method), the reference value may be determined by the reception quality when the radio terminal receives the control signal.

By determining the reference value based on the reception quality when the wireless terminal receives the control signal, the reference value is determined according to the environment (interference situation, obstacle situation, etc.) where the wireless terminal and the base station are located. This is preferable because the value can be determined.

A mobile communication system according to the present invention includes the above control device, a base station controlled by the control device, and a wireless terminal capable of communicating with the base station. Is set by the control device.

The mobile communication system according to the present invention includes the above-described control device, and the control device determines a communication type, a handover reason, a base station interval before and after the handover, or a distance between the handover destination base station and the wireless terminal. By setting the initial value of the transmission power, it is possible to easily and appropriately set the initial value of the transmission power and realize high-quality communication.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the mobile communication system according to the present invention will be described below in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(First Embodiment) FIG. 1 is a diagram showing a configuration of a mobile communication system according to the present embodiment. As shown in FIG. 1, the mobile communication system includes a wireless terminal 10, a base station 20 that performs communication with the wireless terminal 10, a wireless terminal 10.
And a control device 30 that controls communication between the base station 20 and the exchange 40 connected to the control device 30.
0 network 50. The wireless terminal 10 is, for example, a terminal such as a mobile phone, and can perform voice communication and data communication between the wireless terminals 10 through the base station 20. In the mobile communication system according to the present embodiment, the communication between the base station 20 and the wireless terminal 10 uses a code multiplexing method in which a different spreading code is assigned to each user (wireless terminal) to share a channel.

Next, the control device 30 according to the first embodiment will be described. FIG. 2 is a diagram showing a configuration of the control device 30. As shown in FIG. 2, the control device 30 includes a communication type determining unit 34 for determining the type of communication, and a reference power determining unit 31 for determining a reference value (reference power) of the transmission power.
And transmission power setting means 32 for setting an initial value of transmission power from the communication type and the reference power, and a channel allocating means 33 for allocating a channel for communication. In addition to the above components, the control device 30 has a function of monitoring communication between the wireless terminal 10 and the base station 20, a function of controlling handover between the base stations 20,
A function for registering the location of the wireless terminal 10 for calling is provided, but is omitted in FIG.

The communication type determining means 34 has a function of determining the type of communication started at the base station 20 controlled by the control device 30. Control device 30 manages the communication type included in the communication start request when there is a communication start request from wireless terminal 10 to base station 20, and when there is a call request for wireless terminal 10 from exchange 40 side. Since the communication type included in the call request is managed, the communication type determination unit 34 starts the communication between the base station 20 and the wireless terminal 10 based on the information on the communication type managed in the control device 30. The communication type of the communication to be performed is determined. Note that, even when communication is started between the wireless terminal 10 and the new base station 20 due to the handover, the control device 30 also controls the communication between the base station 20 and the wireless terminal 10 before the handover. Refer to that information.

The reference power determining means 31 has a function of determining a reference value of the transmission power. The reference value when communication between the new base station 20 and the wireless terminal 10 is started by handover is determined as follows. A base station 20
If the communication quality deteriorates while communication is being performed with the wireless terminal 10, the control device 30 instructs the wireless terminal 10 to search for another base station 20 existing in the vicinity. Then, when the wireless terminal 10 receives a control signal from another base station 20, it measures the reception quality of the control signal and transmits information on the reception quality to the control device 30. The control device 30 selects the base station 20 having the best reception quality as the handover destination based on the information on the reception quality transmitted from the wireless terminal 10, but based on the information on the reception quality acquired at that time, the transmission power Determine the reference value. For example, the power at which the base station 20 transmits a control signal is P0, the signal-to-noise power ratio at the wireless terminal 10 is R0, and the signal-to-noise power ratio required for the wireless terminal 10 to maintain a predetermined quality when receiving a communication signal. Is R1 and the correction value is C, the reference value P of the transmission power is P = P0 × R1 /
It can be determined by R0 × C. The method of determining the reference value shown here is an example, and the reference value may be determined by another method. For example, the reference value may use a predetermined value, or the base station 2
It may be determined according to the traffic volume to zero.

The transmission power setting means 32 has a function of setting an initial value of the transmission power based on the reference value determined by the reference power determination means 31 and the communication type determined by the communication type determination means 34. Specifically, if the communication is voice communication as a result of the determination by the communication type determination means 34, a predetermined value DH is added to the reference power P to set the initial value of the transmission power. That is, the transmission power PS when the communication type is voice communication is set as PS = P + DH. Conversely, when the communication type is the data communication, a predetermined value DL is subtracted from the reference power P to set the initial value of the transmission power. That is, the transmission power PS when the communication type is data communication is set to PS = P-DL. Here, the predetermined values DH and DL are determined as follows. The predetermined value DH is set so that the transmission power P + DH can receive a signal from the base station 20 regardless of the position of the radio terminal 10 without quality deterioration. The setting is made so that the transmission of the signal does not cause deterioration of the communication quality of the same cell or another cell.

The channel allocating means 33 has a function of determining a channel to which a communication to be started is allocated and allocating the channel.

Next, a transmission power control method in the mobile communication system according to the first embodiment will be described, and a transmission power control method according to the embodiment will also be described. FIG.
5 is a flowchart showing an operation of transmission power control.
Here, a case will be described where handover is performed from base station 20A to base station 20B, and communication between new base station 20B and wireless terminal 10 is started. First, the wireless terminal 10 measures received power of a control signal transmitted from the base station 20 (S10), and transmits information on the measured received power to the control device 30 (S12). When receiving the information on the reception power transmitted from the wireless terminal 10, the control device 30
The reference value of the transmission power is determined by the reference power determination means 31 based on the information of the reception power (S14). The information of the determined transmission power reference value is stored in the transmission power setting unit 32.
Is input to

Next, the control device 30 determines the type of communication to be handed over by the communication type determination means 34 (S20). The result of the determination by the communication type determining unit 34 is input to the transmission power setting unit 32.

Subsequently, the transmission power setting means 32 sets an initial value of the transmission power based on the input reference value of the transmission power and the communication type. If the communication type is voice communication, the initial value PS of the transmission power is set to P + DH (S2).
2) If the communication type is data communication, the initial value PS of the transmission power is set to P-DL (S24).

Next, the control device 30
3, a channel used for communication between the base station 20B and the wireless terminal 10 is allocated. And the control device 30
Is the transmission power PS set in the assigned channel
In addition, the base station 20B is instructed to transmit a signal (S90), and the wireless terminal 10 is also instructed to switch to the assigned channel (S92).

Then, it is determined whether or not the handover is successful (S94). If the handover is successful, the control device 30 instructs the base station 20A before the handover to stop the signal (S96), and the handover is performed. Is not successful, the control device 30 instructs the handover destination base station 20B to stop the signal (S9).
8).

The operation of setting the initial value of the transmission power at the time of starting communication with a new base station 20B by handover by the mobile communication system according to the present embodiment has been described above. During communication with the wireless terminal 10, a conventional control method such as controlling transmission power based on the SIR of a control signal received by the wireless terminal 10 can be employed. During communication, a control signal is transmitted and received between the wireless terminal 10 and the base station 20B in a very short time, so that sufficiently accurate transmission power control can be performed by the conventional control method.

In the mobile communication system according to the first embodiment, the control device 30 includes the communication type determining means 34, and determines the initial value of the transmission power based on the communication type determined by the communication type determining means 34. Therefore, even if the reception quality fluctuates due to a time difference from the time when the reception quality of the control signal is measured to the time when the initial value of the transmission power is determined, the initial value of the transmission power that can cope with the fluctuation can be determined. When the communication type is voice communication, setting the transmission power higher than the reference value of transmission power can prevent loss of signals and maintain high communication quality. By setting the initial value of the transmission power to be lower than the reference value, it is possible to reduce interference with other communications. When a code multiplexing method is used as a multiplexing method as in the mobile communication system according to the present embodiment, transmission of a multiplexed signal is compared with other multiplexing methods such as a time division method or a frequency division method. Since a large power has a large effect on other signals, the present mobile communication system capable of reducing interference is particularly effective.

Also, in the transmission power control method according to the embodiment, the initial value of the transmission power can be appropriately set, as in the above-described mobile communication system.

(Second Embodiment) Next, a mobile communication system according to a second embodiment will be described. The mobile communication system according to the second embodiment has the same basic configuration as the mobile communication system according to the first embodiment (see FIG. 2).
The communication type determining means 34 and the transmission power setting means 32 of the control device 30 in the second embodiment are different from those in the first embodiment.

Here, the functions of the communication type determining means 34 and the transmission power setting means 32 will be described.

[0060] The communication type determining means 34 has a function of determining the communication type of another communication in a channel in which communication started between the base station 20 and the wireless terminal 10 is multiplexed. When there are a plurality of multiplexed communications, the communication type is determined for all of the communications. The determined result is input to the transmission power setting means 32.

The transmission power setting means 32 sets an initial value of the transmission power based on the reference value of the transmission power determined by the reference power determination means 31 and the communication type determined by the communication type determination means 34. Has functions. When the communication type of at least one of the communications multiplexed on the same channel is voice communication, the transmission power setting unit 32 sets the initial value of the transmission power to be lower than the reference value. That is, the initial value of the transmission power is set to PS = P-DL. If the communication types of the multiplexed communication are all data communication, the transmission power setting unit 32 sets the initial value of the transmission power higher than the reference value. That is, the initial value of the transmission power is set to PS = P + DH. Here, the relationship between the communication type of the other multiplexed communication and the initial value setting is shown in FIG. 4 as an example of the case where there are three other multiplexed communication. As shown in FIG. 4, if even one of the communication types of other multiplexed communication is voice communication, the transmission power is set lower than the reference value. In many cases, the initial value of the transmission power is set lower than the reference value.

Next, a transmission power control method in the mobile communication system according to the second embodiment will be described, and a transmission power control method according to the embodiment will also be described. FIG.
5 is a flowchart showing an operation of transmission power control.

The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the radio terminal 10 is the same as that of the mobile communication system according to the first embodiment.

Next, the control device 30 determines the communication type of another communication multiplexed on the channel to which the communication started between the base station 20 and the radio terminal 10 is allocated by the communication type determining means 34 ( S26). If at least one of the other communication types is voice communication, the initial value of the transmission power is set lower than the reference value (S28). If all other communication types are data communication, the transmission power reference value is set. The value is set high (S30).

The operation after the transmission power setting means 32 sets the initial value of the transmission power is the same as the operation of the mobile communication system according to the first embodiment.

The mobile communication system according to the second embodiment
Since the control device 30 includes the communication type determination unit 34 and determines the initial value of the transmission power based on the communication type of another communication multiplexed on the same channel determined by the communication type determination unit 34, Even if the reception quality fluctuates due to a time lag from the time when the signal reception quality is measured to the time when the initial value of the transmission power is determined, the initial value of the transmission power that can cope with the fluctuation can be determined. Further, when the communication type of at least one other communication is voice communication, by setting the communication power lower than the reference value of the transmission power, interference with voice communication transmitted at a high transmission power is reduced, and When all communication types are data communication, the communication quality can be improved by setting the initial value of the transmission power higher than the reference value.

Further, in the transmission power control method according to the embodiment, similarly to the above-described mobile communication system, the initial value of the transmission power can be appropriately set.

(Third Embodiment) Next, a mobile communication system according to a third embodiment will be described. The mobile communication system according to the third embodiment has the same basic configuration as the mobile communication system according to the first embodiment (see FIG. 2).
The communication type determining means 34 and the transmission power setting means 32 of the control device 30 in the third embodiment are different from those in the first embodiment.

Here, the functions of the communication type determining means 34 and the transmission power setting means 32 will be described.

The communication type determination means 34 determines the communication type of communication multiplexed on a channel in another cell having the same frequency as the channel on which communication started between the base station 20 and the radio terminal 10 is multiplexed. Has functions. In addition,
“Cell” means a regional range in which the base station 20 can communicate with the wireless terminal 10, and “other cell” means a base station 20 different from the cell of the base station 20 that is to start communication. Means cell. When there are a plurality of multiplexed communications, the communication type is determined for all of the communications. The determined result is input to the transmission power setting means 32.

The transmission power setting means 32 sets an initial value of the transmission power based on the reference value of the transmission power determined by the reference power determination means 31 and the communication type determined by the communication type determination means 34. Has functions. When the communication type of at least one of the multiplexed communications is voice communication, the transmission power setting unit 32 sets the initial value of the transmission power to be lower than the reference value. That is, the initial value of the transmission power is set to PS = P-DL. If the communication types of the multiplexed communication are all data communication, the transmission power setting unit 32 sets the initial value of the transmission power higher than the reference value. That is, the initial value of the transmission power is set to PS = P + DH.

Next, a transmission power control method in the mobile communication system according to the third embodiment will be described, and a transmission power control method according to the embodiment will also be described. FIG.
5 is a flowchart showing an operation of transmission power control.

The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the radio terminal 10 is the same as that of the mobile communication system according to the first embodiment.

Next, control device 30 communicates the communication type of another communication multiplexed on a channel of another cell having the same frequency as the channel to which communication started between base station 20 and wireless terminal 10 is allocated. The type is determined by the type determination unit 34 (S32). If at least one of the other communication types is voice communication, the initial value of the transmission power is set lower than the reference value (S34). If all other communication types are data communication, the transmission power reference value is set. Set a higher value (S3
6).

Then, the operation after the initial value of the transmission power is set by the transmission power setting means 32 is the same as the operation of the mobile communication system according to the first embodiment.

The mobile communication system according to the third embodiment comprises:
The control device 30 includes a communication type determination unit 34, and determines an initial value of transmission power based on the communication type of another communication multiplexed on the same frequency channel of another cell determined by the communication type determination unit 34. ing. Even in a channel of another base station 20, interference may occur with a channel used at the same frequency and at the same time. Therefore, it is preferable to reduce interference with a channel of another cell. When at least one of the other communication types is voice communication, the transmission power setting unit 32 sets the transmission power to a value lower than the reference value of the transmission power so that the voice in a channel of another cell transmitted at a high transmission power is transmitted. If interference with communication is reduced and all other communication types are data communication, the communication quality can be improved by setting the initial value of the transmission power higher than the reference value.

Further, in the transmission power control method according to the embodiment, similarly to the above-described mobile communication system, the initial value of the transmission power can be appropriately set.

(Fourth Embodiment) Next, a mobile communication system according to a fourth embodiment will be described. The mobile communication system according to the fourth embodiment has the same basic configuration as the mobile communication system according to the first embodiment (see FIG. 2).
The transmission power setting means 32 and the channel allocating means 33 of the control device 30 in the fourth embodiment are different from those in the first embodiment.

Here, the functions of the channel allocating unit 33 and the transmission power setting unit 32 will be described. The channel assignment unit 33 according to the fourth embodiment
Has a function of allocating a channel for communication performed between the wireless terminal 10 and the wireless terminal 10, and has a function of preferentially allocating a channel to which no other multiplexed communication exists when performing the channel allocation. Further, the channel allocating unit 33 has a function of notifying the transmission power setting unit 32 of whether or not the allocation of a channel having no other multiplexed communication has succeeded.

Transmission power setting means 3 in the fourth embodiment
2 is that the transmission power is determined on the basis of the reference value of the transmission power determined by the reference power determination means 31 and the communication type determined by the communication type determination means 34.
Although the same as the transmission power setting unit 32 in the embodiment, the transmission power setting unit 32 in the fourth embodiment further includes:
The initial value of the transmission power is determined based on the notification from the channel allocating unit 33 on whether or not the channel having no other multiplexed communication has been successfully allocated.
That is, when the transmission power setting unit 32 receives a notification from the channel allocating unit 33 that the channel having no other multiplexed communication has been successfully allocated,
It has a function of setting the initial value of the transmission power to be higher than the reference value regardless of the communication type determined by the communication type determining means 34.

Next, a transmission power control method in the mobile communication system according to the fourth embodiment will be described, and a transmission power control method according to the embodiment will also be described. FIG.
5 is a flowchart showing an operation of transmission power control.
The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the wireless terminal 10 is the first operation.
This is the same as the case of the mobile communication system according to the embodiment.

Next, the control device 30
3, a channel used for communication started between the base station 20 and the wireless terminal 10 is allocated (S38). At this time, the channel allocating unit 33 preferentially allocates a channel having no other multiplexed communication. Then, the channel allocating unit 33 notifies the transmission power setting unit 32 whether or not a channel having no other multiplexed communication has been allocated.

Subsequently, the transmission power setting means 32 determines the initial value of the transmission power based on the notification from the channel allocation means 33. That is, it is determined whether or not a channel having no other multiplexed communication has been successfully allocated (S40).
Sets the initial value of the transmission power higher than the reference value (S4
2). That is, transmission power PS = P + DH. Conversely, if it fails to allocate a channel where no other multiplexed communication exists, the transmission power setting means 32
Sets the initial value of the transmission power based on the communication type, as in the first embodiment. That is, the communication type to be started between the base station 20 and the wireless terminal 10 is determined (S44),
If the communication type is voice communication, the initial value of the transmission power is set higher than the reference value (S46). If the communication type is data communication, the initial value of the transmission power is set lower than the reference value. (S48).

The operation after the initial value of the transmission power is set by the transmission power setting means 32 is the same as the operation of the mobile communication system according to the first embodiment.

The mobile communication system according to the fourth embodiment
Since the initial value of the transmission power is set according to the communication type of the communication started between the base station 20 and the wireless terminal 10,
As in the mobile communication system according to the first embodiment, an initial value of transmission power can be appropriately set.

Further, in the mobile communication system according to the fourth embodiment, the channel allocating means 33 allocates a channel where no other multiplexed communication exists, and if the allocation is successful, the initial value of the transmission power is increased. Since the setting is performed, communication quality can be improved using a channel with less interference.

(Fifth Embodiment) Next, a mobile communication system according to a fifth embodiment will be described. The mobile communication system according to the fifth embodiment has the same basic configuration as the mobile communication system according to the fourth embodiment (see FIG. 2).
The channel assignment means 33 of the control device 30 in the fifth embodiment is different from the channel assignment means 3 in the fourth embodiment.
Different from 3.

Here, the function of the channel allocating means 33 will be described. The channel allocating unit 33 according to the fifth embodiment has a function of allocating a channel for communication performed between the base station 20 and the wireless terminal 10, but is multiplexed when the channel is allocated. It has a function of preferentially assigning a channel whose communication type is data communication for all communications. Furthermore, the channel allocating unit 33 has a function of notifying the transmission power setting unit 32 of whether or not the other multiplexed communication has succeeded in allocating a channel that is a data communication.

Transmission power setting means 3 in the fifth embodiment
2 sets the initial value of the transmission power based on the notification first transmitted from the channel allocation unit 33, similarly to the transmission power setting unit 32 in the fourth embodiment. That is, when the transmission power setting unit 32 receives from the channel allocating unit 33 a notification that the other multiplexed communication has succeeded in allocating a channel that is a data communication, the transmission type setting unit 32 determines the transmission type. Regardless of the communication type
It has a function to set the initial value of the transmission power higher than the reference value. When the notification that the channel to be multiplexed other than the data communication cannot be allocated is received from the channel allocating unit 33, the communication type is determined based on the communication type in the same manner as the transmission power control unit in the first embodiment. To set the initial value of the transmission power.

Next, a transmission power control method in the mobile communication system according to the fifth embodiment will be described, and a transmission power control method according to the embodiment will be described. FIG.
5 is a flowchart showing an operation of transmission power control.
The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the wireless terminal 10 is the first operation.
This is the same as the case of the mobile communication system according to the embodiment.

Next, the control device 30
According to 3, a channel used for communication started between the base station 20 and the wireless terminal 10 is allocated (S50). At this time, the channel assigning means 33 preferentially assigns a channel whose communication type is data communication for all other multiplexed communications. Then, the channel allocating unit 33 notifies the transmission power setting unit 32 of whether or not the other multiplexed communication has been able to allocate the channel that is the data communication.

Subsequently, the transmission power setting means 32 determines the initial value of the transmission power based on the notification from the channel allocation means 33. That is, it is determined whether or not the other multiplexed communication has succeeded in allocating a channel that is a data communication (S52). If successful, the transmission power setting means 32 sets the initial value of the transmission power to the reference value. Set higher (S
54). That is, transmission power PS = P + DH. Conversely, if the other multiplexed communication fails to allocate the channel that is the data communication, the transmission power setting means 32 determines the initial value of the transmission power based on the communication type, as in the first embodiment. Set. That is, the communication type of communication started between the base station 20 and the wireless terminal 10 is determined (S56), and if the communication type is voice communication, the initial value of the transmission power is set higher than the reference value ( (S58) If the communication type is data communication, the initial value of the transmission power is set lower than the reference value (S60).

The operation after the initial setting of the transmission power by the transmission power setting means 32 is the same as the operation of the mobile communication system according to the first embodiment.

The mobile communication system according to the fifth embodiment comprises:
Since the initial value of the transmission power is set according to the communication type of the communication started between the base station 20 and the wireless terminal 10,
As in the mobile communication system according to the first embodiment, an initial value of transmission power can be appropriately set.

Further, in the mobile communication system according to the fifth embodiment, the channel allocating means 33 allocates a channel which is a data communication to be multiplexed, and if the allocation is successful, the initial value of the transmission power is reduced. Set high. That is, when multiplexed with data communication capable of communicating with low transmission power, communication quality can be improved using a channel with reduced interference.

(Sixth Embodiment) Next, a mobile communication system according to a sixth embodiment will be described. Although the mobile communication system according to the sixth embodiment has the same basic configuration as the mobile communication system according to the first embodiment, the control device 30A according to the sixth embodiment performs a handover instead of the communication type determination unit 34. The difference from the control device 30 in the first embodiment is that the control device 30 includes a reason determining means 35 for determining the reason for the above. FIG. 9 is a diagram illustrating a configuration of a control device 30A according to the sixth embodiment.

As shown in FIG. 9, the control device 30A
Is the reason determining means 35 for determining the reason for the handover.
A reference power determination unit 31 for determining reference power, a transmission power setting unit 32 for setting an initial value of transmission power from the communication type and the reference power, and a channel allocation unit 33 for allocating a channel for communication. Have.

The reference power determining means 31 and the channel allocating means 33 correspond to the reference power determining means 3 in the first embodiment.
1 and the same as the channel assignment means 33.

The reason judging means 35 has a function of judging the reason for performing the handover. The reason for performing the handover from one base station 20 to another base station 20 is that the communication quality between the one base station 20 and the wireless terminal 10 is deteriorated, and the traffic of the one base station 20 is different. Is sometimes increased. The reason determination means 35 determines which reason the handover is to be performed. Since the control device 30A has a function of monitoring communication between the base station 20 and the wireless terminal 10 and controlling handover, the control device 30A
Can determine the reason for the handover by looking at the history of its own control. Also, the reason determining means 3
5 is input to the transmission power setting means 32.

The transmission power setting means 32 compares the reference power determined by the reference power determining means 31 with the reason determination means 3.
5 has a function of setting an initial value of the transmission power based on the reason for the handover determined in Step 5. Specifically, when the reason for the handover is determined by the reason determination unit 35 and the communication quality is deteriorated, the reference power P
And a predetermined value DH is added to the initial value of the transmission power. That is, the transmission power PS when the reason for the handover is due to the deterioration of the communication quality is PS = P + DH. Conversely, when the reason for the handover is due to the distribution of the traffic, the predetermined value DL is subtracted from the reference power P and the initial transmission power Value. That is, the transmission power PS when the reason for the handover is due to traffic distribution is set as PS = P-DL.

Next, a transmission power control method in the mobile communication system according to the sixth embodiment will be described, and a transmission power control method according to the embodiment will also be described. FIG.
0 is a flowchart showing the operation of transmission power control. Here, a case will be described where handover is performed from base station 20A to base station 20B, and communication between new base station 20B and wireless terminal 10 is started. The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the wireless terminal 10 is the same as that of the mobile communication system according to the first embodiment.

Subsequently, the transmission power setting means 32 sets an initial value of the transmission power based on the input reference value of the transmission power and the reason for the handover. That is, the reason for the handover is determined (S62).
DH is set (S64), and if the reason for the handover is due to traffic distribution, the initial value PS of the transmission power is set to P-
DL is set (S66).

The operation after the initial setting of the transmission power is set by the transmission power setting means 32 is the same as the operation of the mobile communication system according to the first embodiment.

In the mobile communication system according to the sixth embodiment, the control device 30 includes the reason determining means 35 and determines the initial value of the transmission power based on the reason for the handover determined by the reason determining means 35. Even when the reception quality fluctuates due to a time difference from the time when the reception quality of the control signal is measured to the time when the initial value of the transmission power is determined,
An initial value of the transmission power that can cope with the fluctuation can be determined.
Also, when the reason for the handover is due to the deterioration of the communication quality, the communication quality can be improved by setting the transmission power to be higher than the reference value. By setting the value lower than the reference value, interference with other communications can be reduced.

Further, in the transmission power control method according to the embodiment, the initial value of the transmission power can be appropriately set as in the above-described mobile communication system.

(Seventh Embodiment) Next, a mobile communication system according to a seventh embodiment will be described. The mobile communication system according to the seventh embodiment has the same basic configuration as the mobile communication system according to the first embodiment, but the control device 30B according to the seventh embodiment includes a communication type determination unit 34. Instead, a base station interval database (hereinafter, referred to as “base station interval DB”) 37 that stores data on the base station intervals controlled by the control device 30B.
The control device 30 according to the first embodiment is different from the control device 30 according to the first embodiment in that the control device 30 includes a base station interval extracting unit 36 that extracts the interval between the base stations 20 performing the handover from the base station interval DB 37. FIG. 11 is a diagram illustrating a configuration of a control device 30B according to the seventh embodiment.

As shown in FIG. 11, the control device 30B
Are a reference power determining means 31 for determining a reference power, a transmission power setting means 32 for setting an initial value of transmission power from a communication type and a reference power, and a base station interval DB 37 storing data on intervals of the base stations 20. And a base station interval extracting unit 36 for extracting the interval between the two base stations 20 performing the handover from the base station interval DB 37, and a channel allocating unit 33 for allocating a channel for communication. Here, the base station interval extracting means 36 and the base station interval DB 37
A base station interval determining means for determining a distance between the base stations before and after the handover is configured.

The reference power determining means 31 and the channel allocating means 33 correspond to the reference power determining means 3 in the first embodiment.
1 and the same as the channel assignment means 33.

The base station interval DB 37 stores data on the installation intervals of a plurality of base stations 20 controlled by the control device 30B. FIG. 12 is a diagram illustrating an example of data stored in the base station interval DB 37. As shown in FIG. 12, the base station interval DB 37 stores information of “base station” specifying two base stations and “distance” indicating the interval between two base stations. Referring to the base station interval DB 37 shown in FIG.
It can be seen that the distance between 0A and the base station 20B is 1.5 km.

The base station interval extracting means 36 calculates the base station interval D
It has a function of extracting information on the interval between the two base stations 20 that perform handover from B37.

The transmission power setting means 32 sets an initial value of the transmission power based on the reference power determined by the reference power determination means 31 and the base station interval extracted by the base station interval extraction means 36. Having. Specifically, when the base station interval at which the handover is performed is larger than a predetermined threshold value, a predetermined value DH is added to the reference power P to set an initial value of the transmission power. That is, the transmission power PS when the base station interval is larger than the predetermined threshold is set as PS = P + DH. Conversely, when the base station interval is smaller than the predetermined threshold value, the predetermined value DL is subtracted from the reference power P to obtain the initial value of the transmission power. That is, the transmission power PS when the base station interval is smaller than the predetermined threshold is set as PS = P-DL.

Next, a transmission power control method in the mobile communication system according to the seventh embodiment will be described, and a transmission power control method according to the embodiment will also be described. FIG.
3 is a flowchart showing the operation of transmission power control. Here, a case will be described where handover is performed from base station 20A to base station 20B, and communication between new base station 20B and wireless terminal 10 is started. The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the wireless terminal 10 is the same as that of the mobile communication system according to the first embodiment.

Subsequently, the base station interval extracting means 36 determines the interval between the two base stations 20 performing the handover by the base station interval DB3.
7 (S68), and inputs information on the determined base station interval to the transmission power setting means 32. The transmission power setting means 32 sets an initial value of the transmission power based on the input reference value of the transmission power and the information on the base station interval. That is, it is determined whether the base station interval is greater than the predetermined threshold (S70). If the base station interval is larger than the predetermined threshold, the initial value PS of the transmission power is set to P +
DH is set (S72), and if the base station interval is smaller than a predetermined threshold, the initial value PS of the transmission power is set to P-DL (S74).

The operation after the transmission power setting means 32 sets the initial value of the transmission power is the same as the operation of the mobile communication system according to the first embodiment.

In the mobile communication system according to the seventh embodiment, the control device 30 includes the base station interval DB 37 and the base station interval extracting means 36, and information on the interval between the two base stations 20 to be handed over is stored in the base station interval. Extraction means 36
Is extracted from the base station interval DB 37. And
Since the transmission power setting means 32 determines the initial value of the transmission power based on the information on the base station interval extracted by the base station interval extraction means 36, the transmission power setting means 32 determines the transmission power of the control signal from the time when the reception quality of the control signal is measured. Even when the reception quality fluctuates due to a time difference before the initial value is determined, the initial value of the transmission power that can cope with the fluctuation can be determined. In addition, when the base station interval is larger than a predetermined threshold, by setting higher than the reference value of the transmission power, communication quality can be increased, and when the base station interval is smaller than the predetermined threshold,
By setting the initial value of the transmission power lower than the reference value, it is possible to reduce interference with other communications.

Further, in the transmission power control method according to the embodiment, similarly to the above-described mobile communication system, the initial value of the transmission power can be appropriately set.

(Eighth Embodiment) Next, a mobile communication system according to an eighth embodiment will be described. Although the mobile communication system according to the eighth embodiment has the same basic configuration as the mobile communication system according to the first embodiment, the control device 30C according to the eighth embodiment performs a handover instead of the communication type determination unit 34. The difference from the control device 30 in the first embodiment lies in that a distance measuring means 38 for measuring the distance between the base station 20 and the wireless terminal 10 is provided. FIG. 14 is a diagram illustrating a configuration of a control device 30C according to the eighth embodiment.

As shown in FIG. 14, control device 30C
Sets the initial value of the transmission power from the distance measuring means 38 for measuring the distance between the handover destination base station 20 and the wireless terminal 10, the reference power determining means 31 for determining the reference power, and the communication type and the reference power. Transmission power setting means 32 and channel allocating means 33 for allocating a channel for communication
And

The reference power determining means 31 and the channel allocating means 33 correspond to the reference power determining means 3 in the first embodiment.
1 and the same as the channel assignment means 33.

The distance measuring means 38 has a function of measuring the distance between the handover destination base station 20 and the wireless terminal 10 at the time of handover. The position where the wireless terminal 10 exists can be specified by, for example, GPS, or can be specified by the propagation loss of control signals from the plurality of base stations 20 and the like. The distance measuring unit 38 is configured to determine the position of the wireless terminal 10 and the position of the handover destination base station 20 based on the position specified by any method according to the related art.
Measure the distance. Information about the distance between the base station 20 and the wireless terminal 10 measured by the distance measuring means 38 is input to the transmission power setting means 32.

The transmission power setting means 32 compares the reference power determined by the reference power determining means 31 with the distance measuring means 3.
8 has a function of setting an initial value of the transmission power based on the distance measured by the step 8. Specifically, when the distance measured by the distance measuring means 38 is larger than a predetermined threshold value, a predetermined value DH is added to the reference power P to set an initial value of the transmission power. That is, the handover destination base station 2
The transmission power PS when the distance between 0 and the wireless terminal 10 is larger than a predetermined threshold is set as PS = P + DH. Conversely, when the distance measured by the distance measuring means 38 is smaller than the predetermined threshold, the predetermined value DL is subtracted from the reference power P to set the initial value of the transmission power. That is, the transmission power PS when the distance between the handover destination base station 20 and the radio terminal 10 is smaller than the predetermined threshold is set to PSP-DL.

Next, a transmission power control method in the mobile communication system according to the eighth embodiment will be described, and a transmission power control method according to the embodiment will be described. FIG.
5 is a flowchart showing the operation of transmission power control. Here, a case will be described where handover is performed from base station 20A to base station 20B, and communication between new base station 20B and wireless terminal 10 is started. The operation up to setting the reference value of the transmission power based on the reception power of the control signal received by the wireless terminal 10 is the same as that of the mobile communication system according to the first embodiment.

Subsequently, the distance measuring means 38 measures the distance between the handover destination base station 20 and the radio terminal 10 (S
76) The information on the measured distance is input to the transmission power setting means 32. Transmission power setting means 32 sets an initial value of transmission power based on the input reference value of transmission power and the distance between base station 20 and wireless terminal 10. That is, the magnitude of the measured distance and the predetermined threshold is determined (S
78) If the measured distance is larger than the predetermined threshold, the initial value PS of the transmission power is set to P + DH (S8).
0), if the measured distance is smaller than a predetermined threshold, the initial value PS of the transmission power is set to P-DL (S8).
2).

The operation after the transmission power setting means 32 sets the initial value of the transmission power is the same as the operation of the mobile communication system according to the first embodiment.

In the mobile communication system according to the eighth embodiment, the control device 30 includes the distance measuring means 38 and the handover destination base station 2 measured by the distance measuring means 38
Since the initial value of the transmission power is determined based on the distance between the wireless terminal 10 and the wireless terminal 10, there is a time difference between when the reception quality of the control signal is measured and when the initial value of the transmission power is determined, and the reception quality is low. Even when there is a change, the initial value of the transmission power that can cope with the change can be determined. When the distance between the base station 20 and the wireless terminal 10 is larger than a predetermined threshold,
By setting the transmission power higher than the reference value, the transmission data from the base station 20 can be reliably transmitted to the wireless terminal 10 and the communication quality can be improved, and the distance between the base station 20 and the wireless terminal 10 can be set to a predetermined value. If the threshold value is smaller than the threshold value, by setting the initial value of the transmission power lower than the reference value, it is possible to reduce interference with other communication.

Further, in the transmission power control method according to the embodiment, the initial value of the transmission power can be appropriately set as in the above-described mobile communication system.

The mobile communication system, the control device, and the transmission power control method according to the present invention have been described in detail using the embodiments. However, the mobile communication system, the control device, and the transmission power control method according to the present invention have been described. Is not limited to the above embodiment.

For example, in the fourth and fifth embodiments, the channel allocating unit 33 gives priority to a channel in which no other multiplexed communication exists or a channel in which the other multiplexed communication is data communication. And notifies the transmission power setting means 32 of information on whether or not the channel allocation has succeeded. The transmission power setting means 32 sets an initial value of transmission power based on the notification from the channel allocation means 33. However, such channel assignment means 3
3 and the functions of the transmission power setting means 32 are included in the channel allocation means 33 and the transmission power setting means 32 of the control device 30 according to the second, third, sixth, eighth, or eighth embodiment. It is good.

Further, the determination for setting the initial value of the transmission power by the transmission power setting means 32 described in the first to eighth embodiments may be arbitrarily combined to set the initial value of the transmission power. FIG. 16 shows an example.

First, a reference value of the transmission power is determined (S1).
00). The method of determining the reference value may be the method described in the mobile communication system according to the first embodiment, or another method such as using a default value. Next, whether or not an empty slot can be allocated to communication started between the base station 20 and the wireless terminal 10, that is, whether or not a channel having no other multiplexed communication can be allocated. Is determined (S102). If it can be allocated to an empty slot, the communication to be started is allocated to the empty slot (S104), and the initial value of the transmission power is set higher than the reference value (S122).

When it is determined that it is not possible to allocate to an empty slot, whether all other multiplexed communications can be allocated to a channel other than voice communication (all multiplexed communications are data communications) Is determined (S
106). If all the communication types of the other multiplexed communication cannot be assigned to the channel that is the data communication, the initial value of the transmission power is set lower than the reference value (S
120). If the communication type of all other multiplexed communications can be assigned to a channel that is a data signal, the channel is assigned (S108), and the process proceeds to the next determination.

Next, it is determined whether or not at least one of the communication types of the communication multiplexed on the channel of the other cell having the same frequency as the channel to which the communication is allocated is a voice communication (S110). If at least one voice communication is included in the communication multiplexed on the channel of another cell, the initial value of the transmission power is set lower than the reference value (S120). If all communications multiplexed on channels of other cells having the same frequency are data communications, the process proceeds to the next determination.

Next, the communication type of the communication (own wireless terminal) to be started between the base station 20 and the wireless terminal 10 is determined (S112). If the communication type of the communication to be started is voice communication, the initial value of the transmission power is set higher than the reference value (S122). Conversely, if the communication is data communication, the process proceeds to the next determination.

Next, the reason for the handover is determined (S114). If the reason for the handover is due to deterioration of communication quality, the initial value of the transmission power is set higher than the reference value (S122). Conversely, if the reason for the handover is not due to the degradation of communication quality (for example, for traffic distribution), the process proceeds to the next determination.

Next, it is determined whether or not the interval between the two base stations 20 before and after the handover is larger than a predetermined threshold (S1).
16). If the base station interval is greater than a predetermined threshold,
The initial value of the transmission power is set higher than the reference value (S12
2). Conversely, if the base station interval is not larger than the predetermined threshold, the process proceeds to the next determination.

Next, it is determined whether or not the distance between the handover destination base station 20 and the radio terminal 10 is larger than a predetermined threshold (S118). If the distance between the handover destination base station 20 and the wireless terminal 10 is larger than a predetermined threshold,
The initial value of the transmission power is set higher than the reference value (S12
2). Conversely, if the distance is not larger than the predetermined threshold, the initial value of the transmission power is set lower than the reference value (S
120).

According to the flow shown in FIG. 16, the initial value of the transmission power can be set by comprehensively taking into account various factors at the start of communication. The order of the determination in the flow illustrated in FIG. 16 is an example, and the determination may be performed in a different order from the flow in FIG.
It is also possible to omit some determinations. Here, it is determined whether the transmission power is set to be higher or lower than the reference value. However, it is also possible to set the transmission power according to a rank determined stepwise.

The configuration shown in FIG. 17 is conceivable as a configuration of the control device 30D for realizing the flow shown in FIG. In FIG. 17, each component configuring the control device 30 </ b> D is the same as the component having the corresponding reference numeral configuring the control device 30 in the first to eighth embodiments, but the communication type determination unit 34 The own wireless terminal communication type determining means 34a having the function of the communication type determining means 34 in the first embodiment, and the multiplex communication type determining means 3 having the function of the communication type determining means 34 in the second embodiment.
4b, and has another cell communication type determination means 34c having the same function as the communication type determination means 34 in the third embodiment.

[0139]

According to the present invention, the initial value of the transmission power is determined based on the determined communication type, so that the initial value of the transmission power can be simply and appropriately set according to the communication type. , Changing the transmission power to be set according to a communication type in which signal retransmission is allowed and a communication type in which signal retransmission is not allowed,
Communication quality can be improved while reducing interference as a whole.

According to the present invention, the transmission power is determined by determining the initial value of the transmission power based on the reason for the handover, the interval between the base stations before and after the handover, and the distance between the handover destination base station and the wireless terminal. The initial value of the power can be easily and appropriately set.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mobile communication system according to an embodiment.

FIG. 2 is a diagram illustrating a control device according to first to fifth embodiments.

FIG. 3 is a flowchart showing an operation of the mobile communication system according to the first embodiment.

FIG. 4 is a diagram illustrating a relationship between a communication type of multiplexed communication and an initial transmission power value.

FIG. 5 is a flowchart showing an operation of the mobile communication system according to the second embodiment.

FIG. 6 is a flowchart showing an operation of the mobile communication system according to the third embodiment.

FIG. 7 is a flowchart showing an operation of the mobile communication system according to the fourth embodiment.

FIG. 8 is a flowchart showing an operation of the mobile communication system according to the fifth embodiment.

FIG. 9 is a diagram illustrating a control device according to a sixth embodiment.

FIG. 10 is a flowchart showing an operation of the mobile communication system according to the sixth embodiment.

FIG. 11 is a diagram illustrating a control device according to a seventh embodiment.

FIG. 12 is a diagram illustrating an example of data stored in a base station interval DB.

FIG. 13 is a flowchart showing an operation of the mobile communication system according to the seventh embodiment.

FIG. 14 is a diagram showing a control device according to an eighth embodiment.

FIG. 15 is a flowchart showing an operation of the mobile communication system according to the eighth embodiment.

FIG. 16 is a diagram illustrating another example of transmission power control.

FIG. 17 is a diagram showing another example of the control device.

FIG. 18 is a flowchart illustrating a conventional transmission power determination method.

[Explanation of symbols]

10: wireless terminal, 20: base station, 30: control device, 31
... Reference power determination means, 32 ... Transmission power setting means, 33 ...
Channel allocating means 34 communication type determining means 35 reason determining means 36 base station interval extracting means 37 base station interval DB 38 distance measuring means 40 switchboard 50
IMT-2000 network.

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Claims (31)

[Claims] 1. A control device for wirelessly controlling communication between a wireless terminal and a base station, the communication type being determined when starting communication between the base station and the wireless terminal. And a transmission power setting means for determining an initial value of transmission power based on a result of the determination by the communication type determination means. 2. The communication type determining means determines whether the communication type is voice communication or data communication, and the transmission power setting means determines the transmission power if the communication type is voice communication. The method according to claim 1, wherein an initial value is set higher than a predetermined reference value, and when the communication type is data communication, an initial value of transmission power is set lower than a predetermined reference value. The control device according to item 1. 3. A control device for wirelessly controlling communication between a wireless terminal and a base station, wherein when starting communication between the base station and the wireless terminal, the control device is multiplexed on a channel to which the communication is assigned. A communication type determining means for determining a communication type of another communication, and a transmission power setting means for determining an initial value of transmission power based on a determination result by the communication type determining means. 4. The communication type determination means determines whether the communication type of another communication is voice communication or data communication, and the transmission power setting means determines that at least one of the communication types is voice communication. In some cases, the initial value of transmission power is set lower than a predetermined reference value, and when all the communication types are data communications, the initial value of transmission power is set higher than a predetermined reference value. The control device according to claim 3, wherein: 5. A control device for wirelessly controlling communication between a wireless terminal and a base station, wherein when starting communication between the base station and the wireless terminal, the same device as a channel to which the communication is allocated is used. A communication type determining unit that determines a communication type of another communication multiplexed on a channel of another cell having a frequency, a transmission power setting unit that determines an initial value of transmission power based on a determination result by the communication type determining unit, A control device comprising: 6. The communication type determination unit determines whether the communication type of another communication is a voice communication or a data communication, and the transmission power setting unit determines that at least one of the communication types is a voice communication. In some cases, the initial value of transmission power is set lower than a predetermined reference value, and when all the communication types are data communications, the initial value of transmission power is set higher than a predetermined reference value. The control device according to claim 5, wherein: 7. The transmission power setting means further comprises: channel allocation means for allocating communication started between the wireless terminal and the base station to a channel on which no other multiplexed communication exists. The control device according to any one of claims 1 to 6, wherein an initial value of transmission power of communication to which a channel is assigned by means is set higher than a predetermined reference value. 8. The transmission power setting means, further comprising: a channel allocating means for allocating a communication started between the wireless terminal and the base station to a channel whose communication type of communication to be multiplexed is data communication. 7. The control according to claim 1, wherein an initial value of transmission power of communication to which a channel is allocated by the channel allocating unit is set higher than a predetermined reference value. apparatus. 9. A control device for wirelessly controlling communication between a wireless terminal and a base station, wherein when performing communication handover between a plurality of base stations, reason determining means for determining a reason for the handover; And a transmission power setting means for determining an initial value of transmission power based on a result of the determination by the reason determination means. 10. The reason determining means determines whether the handover is performed for deterioration of radio quality or traffic distribution, and the transmission power setting means determines whether handover is performed for deterioration of radio quality. When handover is performed, the initial value of the transmission power is set higher than a predetermined reference value. When handover is performed for traffic distribution, the initial value of the transmission power is set lower than the predetermined reference value. The control device according to claim 9, wherein: 11. A control device for wirelessly controlling communication between a wireless terminal and a base station, wherein the base station determines an interval between the two base stations when handing over communication between the two base stations. A control device, comprising: an interval determination unit; and a transmission power setting unit that determines an initial value of transmission power based on a base station interval obtained by the base station interval determination unit. 12. The transmission power setting means sets an initial value of transmission power higher than a predetermined reference value when the base station interval obtained by the base station interval determination means is larger than a predetermined threshold value. The control device according to claim 11, wherein the control device sets the initial value of the transmission power to be lower than a predetermined reference value when the base station interval is smaller than a predetermined threshold value. 13. A control device for wirelessly controlling communication between a wireless terminal and a base station, wherein when performing communication handover between a plurality of base stations, a distance between the handover destination base station and the wireless terminal is determined. A control device comprising: a distance measuring unit to be obtained; and a transmission power setting unit that determines an initial value of transmission power based on a distance between the base station and the wireless terminal obtained by the distance measuring unit. 14. The transmission power setting means sets an initial value of transmission power higher than a predetermined reference value when the distance measured by the distance measurement means is larger than a predetermined threshold value. 14. The control device according to claim 13, wherein when the station interval is smaller than a predetermined threshold, the initial value of the transmission power is set lower than a predetermined reference value. 15. The control device according to claim 1, wherein the reference value of transmission power is determined based on reception quality when the wireless terminal receives a control signal. . 16. A control device according to claim 1, comprising: a base station controlled by the control device; and a wireless terminal capable of communicating with the base station. Wherein the transmission power from the base station to the wireless terminal is set by the control device. 17. A transmission power control method for controlling transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, comprising: When starting communication at, a communication type determination step of determining the communication type, and a transmission power setting step of determining an initial value of transmission power based on the determination result in the communication type determination step, Transmission power control method to perform. 18. The communication type determining step determines whether the communication type is voice communication or data communication. In the transmission power setting step, when the communication type is voice communication, 18. The method according to claim 17, wherein an initial value is set higher than a predetermined reference value, and when the communication type is data communication, an initial value of transmission power is set lower than a predetermined reference value. 3. The transmission power control method according to 1. 19. A transmission power control method for controlling transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, comprising: A communication type determining step for determining a communication type of another communication multiplexed on a channel to which the communication is allocated when starting communication in the step, and determining an initial value of transmission power based on a determination result in the communication type determining step A transmission power setting step of performing transmission power control. 20. The communication type determining step determines whether the communication type is voice communication or data communication. In the transmission power setting step, if at least one of the communication types is voice communication, Setting the initial value of the transmission power lower than a predetermined reference value, and setting the initial value of the transmission power higher than the predetermined reference value when all the communication types are data communication; The transmission power control method according to claim 19, wherein: 21. A transmission power control method for controlling transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a radio terminal and a base station, comprising: A communication type determining step of determining a communication type of another communication multiplexed on a channel of another cell having the same frequency as a channel to which the communication is allocated when starting communication in the communication type determination step; A transmission power setting step of determining an initial value of the transmission power based on the transmission power control method. 22. The communication type determining step determines whether the communication type is voice communication or data communication. In the transmission power setting step, if at least one of the communication types is voice communication, Setting the initial value of the transmission power lower than a predetermined reference value, and setting the initial value of the transmission power higher than the predetermined reference value when all the communication types are data communication; The transmission power control method according to claim 21, wherein: 23. The transmission power setting step further comprises a channel allocation step of allocating a communication started between the radio terminal and the base station to a channel where no other multiplexed communication exists. 23. The transmission power control method according to claim 17, wherein an initial value of the transmission power of the communication to which the channel is allocated in the step is set higher than a predetermined reference value. 24. The transmission power setting step, further comprising: a channel allocation step of allocating a communication started between the wireless terminal and the base station to a channel whose communication type of communication to be multiplexed is data communication. The transmission according to any one of claims 17 to 22, wherein an initial value of transmission power of communication to which a channel is allocated in the channel allocation step is set higher than a predetermined reference value. Power control method. 25. A transmission power control method for controlling the transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, comprising: A transmission power control step of: determining a reason for the handover when performing a handover; and a transmission power setting step of determining an initial value of transmission power based on a determination result in the reason determination step. Method. 26. In the reason determination step, it is determined whether the handover is performed for deterioration of radio quality or for traffic distribution. In the transmission power setting step, the handover is performed for radio quality deterioration. When handover is performed, the initial value of the transmission power is set higher than a predetermined reference value. When handover is performed for traffic distribution, the initial value of the transmission power is set lower than the predetermined reference value. The transmission power control method according to claim 25, wherein: 27. A transmission power control method for controlling transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, comprising: A base station interval determining step for determining an interval between the two base stations when performing handover; a transmission power setting step for determining an initial value of transmission power based on the base station interval determined in the base station interval determining step; And a transmission power control method comprising: 28. In the transmission power setting step, when the base station interval obtained in the base station interval determination step is larger than a predetermined threshold, the transmission power initial value is set higher than a predetermined reference value. 28. The transmission power control method according to claim 27, wherein, when the base station interval is smaller than a predetermined threshold, the initial value of the transmission power is set lower than a predetermined reference value. 29. A transmission power control method for controlling the transmission power of a base station at the start of communication by a control device for wirelessly controlling communication between a wireless terminal and a base station, comprising: When performing a handover, a distance measuring step of determining a distance between the base station of the handover destination and the wireless terminal, and determining an initial value of transmission power based on the distance between the base station and the wireless terminal determined in the distance measuring step A transmission power setting step of performing transmission power control. 30. In the transmission power setting step, when the distance measured in the distance measurement step is larger than a predetermined threshold, an initial value of transmission power is set to be higher than a predetermined reference value. 30. The transmission power control method according to claim 29, wherein when the station interval is smaller than a predetermined threshold, the initial value of the transmission power is set lower than a predetermined reference value. 31. The transmission power according to claim 17, wherein the reference value of transmission power is determined by reception quality when the wireless terminal receives a control signal. Control method.