JP2010062951A - Base station and mobile communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain communication quality inside a femto cell even when a macro mobile unit 40 being proximate to a femto base station 10 communicates with a macro base station 30. <P>SOLUTION: A femto base station 10 includes: a downlink perch channel signal transmission power control unit 11 for varying transmission power of a downlink perch channel signal for a first cell; an uplink reception sensitivity control unit 12 for making dull uplink reception sensitivity in the first cell when the transmission power of the downlink perch channel signal for the first cell is reduced and where it is determined that a first condition is satisfied; and a control unit 13 which switches a communication of a mobile unit in the first cell to a communication in a second cell using a second frequency when the transmission power of the downlink perch channel signal for the first cell is reduced and where it is determined that a second condition is satisfied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a base station (specifically, a femto base station) and a mobile communication method.

  In recent years, base stations that can be arbitrarily installed by users have been developed, and such base stations have subordinate cell radii as compared to “macro base stations” that are installed, designed, and operated by communication carriers. Because it is small, it is called a “femto base station”.

Since the installation location of the femto base station may be out of the control of the carrier, such a femto base station reduces the radius of the subordinate cell so as not to interfere with the existing macro base station, Conversely, a cell that can expand the radius of a subordinate cell to overcome interference from an existing macro base station, or can expand / reduce the radius of a subordinate cell to cover a desired communication area. It is considered to have an autonomous radius adjustment function.
JP-A-8-289366

  Here, when the femto base station reduces the radius of the subordinate cell, the macro mobile device that is not registered in the femto base station is in close proximity to the femto base station. A situation may occur in which communication is performed with a macro base station without performing communication with a station.

  In such a case, since the macro base station is far away from the femto base station, the macro mobile station performs uplink transmission with high power, and the femto base station adjacent to the macro mobile station causes a large interference. As a result, there has been a problem that the uplink communication quality between the femto mobile station and the femto base station may be deteriorated or communication may not be possible.

  In other words, the conventional femto base station changes the transmission power of the downlink perch channel signal according to the interference situation with the surrounding base station (macro base station), the traffic congestion state, and the necessity on the service, Although the radius of the downlink femto cell can be changed, there has been a problem that the uplink communication quality may be deteriorated when only the size of the downlink femto cell is changed.

  Therefore, the present invention has been made in view of the above-described problems, and maintains the communication quality in the femtocell even when a macro mobile station that is close to the femto base station communicates with the macro base station. An object of the present invention is to provide a base station (femto base station) and a mobile communication method.

  A first feature of the present invention is a base station configured to provide a communication service in a first cell in which a first frequency is used, and transmission power of a downlink perch channel signal for the first cell. When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit configured to change the downlink perch channel signal transmission power control unit And when it is determined that the first condition is satisfied, the uplink reception sensitivity control unit configured to slow down the uplink reception sensitivity in the first cell, and the downlink perch channel signal transmission power control When the transmission power of the downlink perch channel signal for the first cell is reduced by the first cell and when it is determined that the second condition is satisfied, the first cell Communication definitive mobile, and summarized in that comprises a second control unit whose frequency is configured to switch the communication in the second cell used.

  A second feature of the present invention is a base station configured to provide a communication service in a first cell in which a first frequency is used, and transmission power of a downlink perch channel signal for the first cell. When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit configured to change the downlink perch channel signal transmission power control unit And when it is determined that the first condition is satisfied, the uplink reception sensitivity control unit configured to slow down the uplink reception sensitivity in the first cell, and the downlink perch channel signal transmission power control When the transmission power of the downlink perch channel signal for the first cell is reduced by the first cell and when it is determined that the second condition is satisfied, the first cell And summarized in that and a control unit configured to stop providing definitive communication services.

  According to a third aspect of the present invention, there is provided a base station configured to provide a communication service in a first cell using a first frequency, the transmission power of a downlink perch channel signal for the first cell. When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit configured to change the downlink perch channel signal transmission power control unit And when it is determined that the first condition is satisfied, the uplink reception sensitivity control unit configured to slow down the uplink reception sensitivity in the first cell, and the downlink perch channel signal transmission power control When the transmission power of the downlink perch channel signal for the first cell is reduced by the first cell and when it is determined that the second condition is satisfied, the first cell It and a control unit configured to change the communication scheme to be used for communication of the mobile station and gist of the.

  According to a fourth aspect of the present invention, there is provided a mobile communication method in which a base station provides a communication service in a first cell using a first frequency, and the base station provides a downlink perch channel for the first cell. A step of changing the transmission power of the signal, and when the transmission power of the downlink perch channel signal for the first cell is reduced and when it is determined that the first condition is satisfied, The step of slowing the uplink reception sensitivity in the first cell, the case where the transmission power of the downlink perch channel signal for the first cell is reduced, and the second condition is determined to be satisfied The base station includes a step of switching the communication of the mobile device in the first cell to the communication in the second cell using the second frequency.

  According to a fifth aspect of the present invention, there is provided a mobile communication method in which a base station provides a communication service in a first cell using a first frequency, and the base station provides a downlink perch channel for the first cell. A step of changing the transmission power of the signal, and when the transmission power of the downlink perch channel signal for the first cell is reduced and when it is determined that the first condition is satisfied, The step of slowing the uplink reception sensitivity in the first cell, the case where the transmission power of the downlink perch channel signal for the first cell is reduced, and the second condition is determined to be satisfied The base station has a step of stopping the provision of the communication service in the first cell.

  According to a sixth aspect of the present invention, there is provided a mobile communication method in which a base station provides a communication service in a first cell using a first frequency, and the base station provides a downlink perch channel for the first cell. A step of changing the transmission power of the signal, and when the transmission power of the downlink perch channel signal for the first cell is reduced and when it is determined that the first condition is satisfied, The step of slowing the uplink reception sensitivity in the first cell, the case where the transmission power of the downlink perch channel signal for the first cell is reduced, and the second condition is determined to be satisfied The base station includes a step of changing a communication method used for communication of a mobile device in the first cell.

  As described above, according to the present invention, even when a macro mobile station that is in proximity to a femto base station communicates with the macro base station, the base station that can maintain the communication quality in the femto cell ( Femto base station) and a mobile communication method can be provided.

(Configuration of mobile communication system according to the first embodiment of the present invention)
The configuration of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS.

  Hereinafter, a mobile device that is registered in advance with the femto base station and performs communication using the femto base station is referred to as a “femto mobile device”, and a base station that provides a public communication service is referred to as a “macro base station”. A mobile device that communicates with the macro base station but does not register with the femto base station and does not communicate with the femto base station is referred to as a “macro mobile device”.

  Basically, the mobile device is configured to monitor the downlink perch channel signal transmitted by the base station and perform standby and communication at the base station having the strongest reception power of the downlink perch channel signal.

  As shown in FIGS. 1 and 2, the mobile communication system according to the present embodiment includes a femto base station 10, a femto mobile device 20, a macro base station 30, and a macro mobile device 40.

  FIG. 1 is a diagram illustrating a state in which a femto cell c2 (a cell publicly constituted by an uplink femto cell U and a downlink femto cell D) under the femto base station 10 exists in the macro cell c1 under the macro base station 30. . FIG. 2 is a diagram illustrating an example in which the femtocell c2 under the control of the femto base station 10 is limited to the user's room.

  As shown in FIG. 3, the femto base station 10 includes a downlink radius determination unit 11, an uplink reception sensitivity determination unit 12, a transceiver control device 13, and a transceiver 14. The femto base station 10 is configured to provide a communication service in the femto cell c2 (first cell) in which the first frequency is used.

  The downlink radius determination unit 11 is configured to change the transmission power of the downlink perch channel signal (downlink pilot channel signal) for the femtocell c2. A specific method for controlling the transmission power of the downlink perch channel signal will be described later.

  The uplink reception sensitivity determination unit 12 is configured to change the uplink reception sensitivity. For example, when the transmission power of the downlink perch channel signal for the femtocell c2 is reduced by the downlink radius determination unit 11 and when it is determined that the first condition is satisfied, the uplink reception sensitivity in the femtocell c2 Is configured to slow down.

  A method for determining whether or not the first condition is satisfied will be described later. Here, the uplink reception sensitivity indicates the input level in the femto base station 10 necessary for maintaining the required quality of uplink communication by the femto mobile device 20, and the smaller the value, the sharper the uplink reception sensitivity.

  The transceiver control device 13 is configured to control the transceiver 14 in response to instructions from the downlink radius determination unit 11 and the uplink reception sensitivity determination unit 12.

  For example, when the downlink radius determination unit 11 determines that the transmission power of the downlink perch channel signal for the femtocell c2 has been reduced by the downlink radius determination unit 11, and the second condition is determined to be satisfied, Communication of the femto mobile device 20 in the femtocell c2 may be configured to be switched to communication in the second cell in which the second frequency is used.

  For example, the second cell is a cell that is at least partially overlapped with the femto cell c2, and is a femto cell under the control of the femto base station 10. Further, it is assumed that the femto mobile device 20 can access the second cell.

  Further, the transceiver control device 13 determines that the downlink radius determining unit 11 reduces the transmission power of the downlink perch channel signal for the femtocell c2 and determines that the second condition is satisfied. It may be configured to stop providing the communication service in the femtocell c2, or change a communication method (for example, an encoding method or a transmission rate) used for communication of the femto mobile device 20 in the femtocell c2. It may be configured.

  Note that a method for determining whether or not the second condition is satisfied will be described later.

  The transceiver 14 is configured to communicate with the femto mobile device 20 registered in advance in response to an instruction from the transceiver control device 13.

  Here, as shown in FIGS. 1 and 2, the downlink radius determination unit 11 determines to reduce the transmission power of the downlink perch channel signal for the downlink femtocell D and to narrow the radius of the downlink femtocell D. However, if the uplink reception sensitivity determination unit 12 does not change the uplink reception sensitivity and leaves the radius of the uplink femtocell U as it is, there is a mismatch between the size of the uplink femtocell U and the size of the downlink femtocell D. Occurs.

  As a result, there is a possibility that uplink interference is given to the femto base station 10 due to uplink communication with the macro base station 30 by the macro mobile device 40 existing between the uplink femto cell U and the downlink femto cell D. is there.

  Specifically, as shown in FIGS. 1 and 2, the macro mobile device 40 existing between the uplink femtocell U and the downlink femtocell D receives the perch channel signal transmitted by the macro base station 30. It is determined that the power is stronger than the received power of the perch channel signal transmitted by the femto base station 10, and communication is performed with the macro base station 30.

  However, since the macro mobile device 40 exists in the upstream femto cell U under the femto base station 10, the radio waves for uplink communication between the macro mobile device 40 and the macro base station 30 are generated by the femto base station 10. There is a risk of uplink interference with respect to.

  Therefore, this problem is solved by the operation of the mobile communication system, which will be described later, specifically, the operation of the femto base station 10.

(Operation of the mobile communication system according to the first embodiment of the present invention)
With reference to FIG. 4 thru | or FIG. 7, operation | movement of the mobile communication system which concerns on the 1st Embodiment of this invention, specifically, operation | movement of the femto base station 10 is demonstrated.

  Specifically, an example in which the femto base station 10 reduces the radius of the downlink femto cell D and the radius of the uplink femto cell U will be described with reference to FIGS. 4 to 7.

  In such an example, as shown in FIG. 4, in the mobile communication system according to the present embodiment, the macro base station b1, the femto base station b2, and the macro base station b1 communicate with each other, but are registered in the femto base station b2. And a macro mobile device u1 that does not communicate with the femto base station b2 and a femto mobile device u2 that is registered in the femto base station b2 and communicates with the femto base station b2.

  Further, the macro cell c1 is managed by the macro base station b1, and the femto cell c2 is managed by the femto base station b2. In the femtocell c2, it is assumed that the reception power of the downlink perch channel signal transmitted by the femto base station b2 is stronger than the reception power of the downlink perch channel signal transmitted by the macro base station b1.

  As shown in FIG. 5, in step S101, the femto base station b2 determines whether or not it is necessary to reduce the radius of the downlink femto cell, that is, whether or not the transmission power of the downlink perch channel signal should be reduced. .

  For example, the femto base station b2 detects that a macro mobile device (unregistered mobile device) u1 has entered the femto cell c2 under the femto base station b2, and the macro mobile device u1 When it is unsuccessful to change the frequency of communication performed with the station b1 to a frequency other than the frequency used in the femto base station b2, it is necessary to reduce the transmission power of the downlink perch channel signal You may judge that there is.

  Here, the femto base station b2 receives the macro mobile station (unregistered mobile station) in the femtocell c2 under the femto base station b2 based on the location registration signal, the outgoing / incoming call request signal, the communication link addition request signal, and the like. ) It is possible to detect that u1 has entered.

  In addition, the femto base station b2 is notified of the femto under the femto base station b2 by a notification from a network (for example, a radio control device RNC in the WCDMA system, an exchange MME (Mobility Management Entity) in the LTE (Long Term Evolution) system, etc.) It may be detected that a macro mobile device (unregistered mobile device) u1 has entered the cell c2.

  For example, when a communicating macro mobile device (unregistered mobile device) u1 enters the femto cell c2 under the femto base station b2, the femto base station b2 is notified to the network as a handover destination base station, and the network However, based on such notification, the femto base station b2 may be notified that the macro mobile device (unregistered mobile device) u1 has entered the femtocell c2 under the femto base station b2. Good.

  When the macro mobile station u1 enters the femtocell c2, the macro mobile station u1 confirms that the measured value related to the femto base station b2 has exceeded the threshold instead of notifying the network of the femto base station b2 as the handover destination base station. You may notify the network. In this case, the network notifies the femto base station b2 that the macro mobile device (unregistered mobile device) u1 has entered the femtocell c2 under the femto base station b2.

  Alternatively, when a waiting macro mobile device (unregistered mobile device) u1 enters the femto cell c2 under the femto base station b2, the femto base station b2 is set as a cell change destination base station in the network. The network is configured to notify the femto base station b2 that the macro mobile device (unregistered mobile device) u1 has entered the femtocell c2 under the femto base station b2 based on the notification. May be.

  When the macro mobile device u1 enters the femtocell c2, the measured value related to the femto base station b2 exceeds the threshold instead of notifying the network of the femto base station b2 as the cell change destination base station. May be notified to the network. In this case, the network notifies the femto base station b2 that the macro mobile device (unregistered mobile device) u1 has entered the femtocell c2 under the femto base station b2.

  Alternatively, when the size of the femto cell c2 under the control of the femto base station b2 exceeds a predetermined value (preset), that is, the transmission power of the downlink perch channel signal (preset) When a predetermined value is exceeded, it may be determined that the transmission power of the downlink perch channel signal needs to be reduced.

  For example, the predetermined value may be a radius of a femtocell including a place set by the user or the like on the circumference, or items selected by the user or the like (for example, “large”, “medium”, “small”). Etc.).

  Further, the femto base station b2 may set the predetermined value based on the communication pattern of the femto mobile device u2. For example, the femto base station b2 stores the reception power of the uplink signal transmitted by the femto mobile device u2, and statistically determines the communication area of the femto mobile device u2 based on the accumulated result of the reception power of the uplink signal. And the predetermined value described above may be set.

The femto base station b2 includes a measuring device that can measure the size of the room by laser, ultrasonic waves, infrared rays, etc., and examines the size of the room using wall reflection. You may set a predetermined value of
Alternatively, when the femto base station b2 determines that the macro base station b1 (neighboring base station) is interfering, the femto base station b2 determines that it is necessary to reduce the transmission power of the downlink perch channel signal. Good.

  For example, when the macro base station b1 detects that the reception power of a downlink signal (for example, a downlink perch channel signal) transmitted by the femto base station b2 exceeds a threshold, that fact and the necessary downlink stop When the femto base station b2 is configured to notify the femto base station b2 of the reduction amount of the transmission power of the tree channel signal by wired communication or wireless communication, the femto base station b2 It can be determined that interference is given to the station b1 (neighboring base station).

  Further, the femto base station b2 always measures the received power (that is, interference power) of the downlink signal (for example, downlink perch channel signal) transmitted by the macro base station b1, and the measurement result is a threshold value. Is detected, it can be determined that the macro base station b1 (neighboring base station) is interfering because it is close to the macro base station b1.

  Alternatively, the femto base station b2 is based on the reception power of the downlink signal transmitted by the macro base station b1 and the transmission power of the downlink signal included in the broadcast signal transmitted by the macro base station b1. When the propagation loss with respect to the macro base station b1 is calculated and it is detected that the propagation loss is equal to or less than the threshold, the macro base station b1 (neighboring base station) On the other hand, it can be determined that interference is given.

  When it is determined that it is not necessary to reduce the radius of the downlink femto cell, in step S102, the femto base station b2 does not change the transmission power of the downlink perch channel signal.

  On the other hand, when it is determined that the radius of the downlink femto cell needs to be narrowed, in step S103, the femto base station b2 calculates a reduction amount of the transmission power of the downlink perch channel signal, and the downlink stops by the reduction amount. Reduce the transmission power of the tree channel signal.

  For example, in step S103, the femto base station b2 uses the received power of the downlink perch channel signal of the femto base station b2 measured by the macro mobile station u1. It may be determined that the transmission power of the downlink perch channel signal is reduced until the femtocell c2 is not selected.

  Here, the femto base station b2 may receive the reception power of the downlink perch channel signal of the femto base station b2 via a network or may receive wirelessly from the macro mobile device u1. .

  In step S103, the user transmits a transmission request signal from a predetermined location using the femto mobile device u2, and the femto base station b2 measures the reception power of the transmission request signal and calculates the propagation loss, Based on the propagation loss, the amount of reduction in the transmission power of the downlink perch channel signal may be determined so as not to reach outside the femtocell c2 having a size equal to a predetermined value set in advance.

  In step S103, the femto base station b2 may determine the amount of reduction in the transmission power of the downlink perch channel signal based on the transmission power stored in association with the item selected by the user or the like.

  Further, in step S103, the femto base station b2 may determine to reduce the transmission power of the downlink perch channel signal by the amount of reduction of the transmission power of the downlink perch channel signal notified by the macro base station b1. Good.

  In step S104, the femto base station b2 refers to the correspondence table of “transmission power of the downlink perch channel” and “uplink reception sensitivity” shown in FIG. 6, and determines whether or not to change the uplink reception sensitivity in step S105. Judge whether or not.

  Note that such a correspondence table may be held in advance by the femto base station b2, a network (for example, a radio control apparatus RNC in the WCDMA system, an exchange MME (Mobility Management Entity) in the LTE (Long Term Evolution) system, etc. ) May be notified to the femto base station b2.

  A plurality of correspondence tables may be provided such as a fine control correspondence table and a rough control correspondence table.

  Here, when the transmission power of the downlink perch channel signal is reduced by a predetermined value or more, the femto base station b2 determines that the uplink reception sensitivity needs to be reduced, and the operation proceeds to step S107.

  If the transmission power of the downlink perch channel signal is not reduced by a predetermined value or more, the femto base station b2 determines that it is not necessary to slow the uplink reception sensitivity, and does not change the uplink reception sensitivity in step S106.

  In step S107, the femto base station b2 determines whether or not uplink interference can be prevented by changing the uplink reception sensitivity (specifically, by reducing the uplink reception sensitivity).

  Here, if it is determined that the uplink interference can be prevented by changing the uplink reception sensitivity, the femto base station b2 determines that the first condition is satisfied in step S108, and slows the uplink reception sensitivity. Let

  On the other hand, if it is determined that the uplink interference cannot be prevented by changing the uplink reception sensitivity, the femto base station b2 determines in step S109 that the second condition is satisfied, and will be described later with reference to FIG. To do alternatives.

  Specifically, as shown in FIG. 6, the femto base station b2 transmits a downlink perch channel signal when the reduced transmission power p of the downlink perch channel is “P0 ≧ p ≧ P1”. It is determined that the power is not reduced by a predetermined value or more, and the uplink reception sensitivity is not changed (the uplink reception sensitivity “S0” remains unchanged).

  Further, the femto base station b2 determines that the reduced downlink perch channel transmission power p is “reduction level” to which the reduced downlink perch channel transmission power p belongs when “P1> p ≧ Pn”. The uplink reception sensitivity is slowed down so that the "uplink reception sensitivity" corresponding to

  The femto base station b2 adopts the above-described alternative means when the transmission power p of the reduced downlink perch channel is “p <Pn”.

  Here, the transmission power of the downlink perch channel before the change is “P0”, the uplink reception sensitivity before the change is “S0”, “P0 ≧ P1 ≧ P2 ≧ ... ≧ Pn”, and “S0 ≦ It is assumed that S1 ≦ S2 ≦.

  In addition, the femto base station b2 increases the amount of variable uplink attenuator provided between the antenna and the receiver, increases the NF in the femto base station b2, and slows the uplink reception sensitivity of the antenna. Thus, it is possible to realize a decrease in uplink reception sensitivity.

  In addition, when the femto base station b2 continuously transmits a transmission power control (TPC) command “DOWN” for the uplink signal of the femto mobile device u2 for a predetermined number of times, the uplink reception sensitivity may be reduced.

  Next, with reference to FIG. 7, an example of the operation | movement which takes the alternative means in step S109 is demonstrated.

  As shown in FIG. 7, when it is determined that the femto base station b2 adopts alternative means, in step S201, the femto base station b2 is used for such communication with respect to the femto mobile device u2 performing communication in the femtocell c2. It is instructed to measure reception quality (for example, reception power level, noise power level, desired wave signal-to-noise power ratio (SIR)) in the second cell in which a second frequency different from the first frequency is used.

  In step S202, the femto base station b2 determines whether or not the reception quality in the second cell exceeds a predetermined threshold according to the measurement result from the femto mobile device u2.

  When it is determined that the reception quality in the second cell exceeds the predetermined threshold, in step S203, the femto base station b2 uses the second frequency for communication of the femto mobile device 20 in the femtocell c2. Instruct to switch to communication in two cells.

  When it is determined that the reception quality in the second cell does not exceed the predetermined threshold, in step S204, the femto base station b2 receives the reception quality in the cell using a frequency other than the first frequency and the second frequency. (For example, the reception power level, noise power level, desired signal to noise power ratio (SIR), etc.) are instructed to be measured.

  Alternatively, when it is determined that the reception quality in the second cell does not exceed the predetermined threshold, in step S204, the femto base station b2 may stop providing the communication service in the femtocell c2 for a certain period. However, a communication method (for example, an encoding method or a transmission rate) used for communication of the femto mobile device 20 in the femtocell c2 may be changed.

(Operations and effects of the mobile communication system according to the first embodiment of the present invention)
According to the mobile communication system according to the first embodiment of the present invention, when the downlink femto cell radius is narrowed by the femto base station c2's downlink femto cell radius autonomous adjustment function, the transmission of the downlink perch channel is performed. The macro mobile station u1 that is in close proximity to the femto base station b2 communicates with the macro base station b1 by slowing the uplink reception sensitivity according to the power reduction amount and narrowing the radius of the upstream femto cell. However, the communication quality in the femtocell c2 of the femto base station b2 can be maintained.

  Further, according to the mobile communication system according to the first embodiment of the present invention, in a situation where interference is severe, when it is determined that uplink interference cannot be prevented by changing the uplink reception sensitivity, By changing the frequency used for communication with the femto base station, the quality of such communication can be maintained.

  Also, according to the mobile communication system according to the first embodiment of the present invention, when it is determined that the uplink interference cannot be prevented by changing the uplink reception sensitivity, the communication is maintained by stopping the service. You can't, but you can protect your femto base station.

  As described above, according to the mobile communication system according to the first embodiment of the present invention, it is possible to cope with any situation, so that the femto base station can be operated more flexibly and can be easily maintained. Play.

(Modification 1)
Next, the mobile communication system according to the first modification of the present invention is described with reference to FIG. Here, the mobile communication system according to the first modification of the present invention will be described by paying attention to differences from the mobile communication system according to the first embodiment.

  Next, with reference to FIG. 7, an example of the operation | movement which takes the alternative means in step S109 is demonstrated.

  Specifically, as shown in FIG. 8, when the femto base station b2 determines to adopt an alternative means in step S109 shown in FIG. 5, in step S301, the femto mobile station 20 communicates in the femto cell c2. A switching destination cell (second cell in which the second frequency is used) is determined, and in step S302, the femto mobile device u2 is instructed to perform communication in the determined second cell.

  In step S303, when the communication of the femto mobile device 20 in the femto cell c2 is successfully switched to the second cell, this operation ends and the communication of the femto mobile device 20 in the femto cell c2 is switched to the second cell. If the operation fails, the operation proceeds to step S304.

  In step S304, the femto base station b2 receives reception quality (for example, reception power level, noise power level, desired wave signal to noise power ratio (SIR)) in a cell using a frequency other than the first frequency and the second frequency. Etc.) to be measured.

  Alternatively, in step S304, the femto base station b2 may stop providing the communication service in the femtocell c2 for a certain period, or a communication method (for example, encoding) used for the communication of the femto mobile device 20 in the femtocell c2. The system, transmission speed, etc.) may be changed.

(Example of change)
In the above-described embodiment, the communication using the macro base station b1 and the femto base station b2 has been described. However, in the present invention, interference between femto base stations with different registered mobile stations (femto mobile devices) is described. It is also effective to avoid it.

  In such a case, the above-described operation is applied assuming that the “macro base station b1” is a “femto base station b4” whose mobile station (femto mobile device) registered with the femto base station b2 is different. Can do.

  Further, the above-described operation of the femto base station 10 may be performed by hardware, may be performed by a software module executed by a processor, or may be performed by a combination of both.

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the femto base station 10. Further, the storage medium and the processor may be provided in the femto base station 10 as a discrete component.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. 1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a functional block diagram of a femto base station according to the first embodiment of the present invention. It is a figure for demonstrating operation | movement of the femto base station which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the femto base station which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the femto base station which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the femto base station which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the femto base station which concerns on the modification 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Femto base station 11 ... Downward radius determination part 12 ... Uplink reception sensitivity determination part 13 ... Transmitter / receiver control apparatus 14 ... Transmitter / receiver 20 ... Femto mobile station 30 ... Macro base station 40 ... Macro mobile station

Claims (6)

A base station configured to provide a communication service in a first cell in which a first frequency is used,
A downlink perch channel signal transmission power control unit configured to change the transmission power of the downlink perch channel signal for the first cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit, and when it is determined that the first condition is satisfied, the first An uplink reception sensitivity control unit configured to slow down the uplink reception sensitivity in the cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit, and when it is determined that the second condition is satisfied, the first A base station comprising: a control unit configured to switch communication of a mobile device in a cell to communication in a second cell in which a second frequency is used. A base station configured to provide a communication service in a first cell in which a first frequency is used,
A downlink perch channel signal transmission power control unit configured to change the transmission power of the downlink perch channel signal for the first cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit, and when it is determined that the first condition is satisfied, the first An uplink reception sensitivity control unit configured to slow down the uplink reception sensitivity in the cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit, and when it is determined that the second condition is satisfied, the first And a control unit configured to stop providing communication services in the cell. A base station configured to provide a communication service in a first cell in which a first frequency is used,
A downlink perch channel signal transmission power control unit configured to change the transmission power of the downlink perch channel signal for the first cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit, and when it is determined that the first condition is satisfied, the first An uplink reception sensitivity control unit configured to slow down the uplink reception sensitivity in the cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced by the downlink perch channel signal transmission power control unit, and when it is determined that the second condition is satisfied, the first A base station comprising: a control unit configured to change a communication method used for communication of a mobile device in a cell. A mobile communication method in which a base station provides a communication service in a first cell in which a first frequency is used,
The base station changing transmission power of the downlink perch channel signal for the first cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced and it is determined that the first condition is satisfied, the base station increases the uplink reception sensitivity in the first cell. A step of slowing down;
When the transmission power of the downlink perch channel signal for the first cell is reduced and when it is determined that the second condition is satisfied, the base station communicates with the mobile station in the first cell. Switching to communication in the second cell in which the second frequency is used. A mobile communication method in which a base station provides a communication service in a first cell in which a first frequency is used,
The base station changing transmission power of the downlink perch channel signal for the first cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced and it is determined that the first condition is satisfied, the base station increases the uplink reception sensitivity in the first cell. A step of slowing down;
When the transmission power of the downlink perch channel signal for the first cell is reduced and it is determined that the second condition is satisfied, the base station provides communication service in the first cell. And a step of stopping the communication. A mobile communication method in which a base station provides a communication service in a first cell in which a first frequency is used,
The base station changing transmission power of the downlink perch channel signal for the first cell;
When the transmission power of the downlink perch channel signal for the first cell is reduced and it is determined that the first condition is satisfied, the base station increases the uplink reception sensitivity in the first cell. A step of slowing down;
When the transmission power of the downlink perch channel signal for the first cell is reduced and it is determined that the second condition is satisfied, the base station communicates with the mobile station in the first cell. And a step of changing a communication method used for the mobile communication method.

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