JP2012138674A - Base station and method of controlling base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base station and a method of controlling the base station which can prevent wasteful power consumption due to the transmission of unnecessary radio waves.SOLUTION: A base station (FAP) of a mobile communication system comprises: a transmission unit (122) for transmitting a pilot beacon to make a mobile station detect its own station; a communication unit (126) for transmitting and receiving a communication radio wave to communicate with a mobile station; a registration unit (141) for registering information on a mobile station using its own station or a user corresponding to the mobile station; and a control unit (110) for controlling the communication unit (126) so that the communication unit does not receive or transmit a communication radio wave when a mobile station corresponding to the information registered in the registration unit (141) is not situated in its communication area, and starts transmitting and receiving a communication radio wave when a mobile station is performing hand-off to the own station.

Description

  The present invention relates to a base station and a control method for the base station, and more particularly to a base station connected to a mobile communication network via a general line and a control method for the base station.

  In recent years, in mobile communication systems, a base station scheme called a femto cell (Home eNode B), which covers a very small area compared to a conventional base station (wide base station, macro cell), has been proposed. A femtocell is a small base station installed in, for example, a house or a small office. A cell phone of a conventional mobile phone, that is, an area covered by one wide area base station has a radius of about 1 to several kilometers. On the other hand, the area covered by the femtocell is about several meters to several tens of meters. The femtocell is connected to a mobile communication network via a general line (a broadband line such as ADSL) drawn into each home. Since general lines are widely used as access lines, even users who are outside the macro cell area can use the same cellular phone service as the macro cell (call, mail function, SMS (Short Message Service), WEB browsing, etc.) if there is a broadband line. ) Can be used inexpensively and easily. In addition, the use of femtocells and broadband lines eliminates the need to use existing wide-area base station resources (bandwidth, etc.) that were originally consumed. It has a merit that can be.

  As described above, in the third generation (3G), the 3.9 generation (3.9G), and the IMT-ADVANCED operated in the frequency band of 2 GHz or higher, an outdoor wide area base station and an indoor femtocell are used. This combination is expected to become essential. Furthermore, since it is desirable that the femtocell be used only by previously registered terminals (mobile devices), the limited number of users registered for use can occupy the femtocell. Therefore, compared to a macro cell that is congested by a plurality of users, there is an advantage that a higher-speed and high-quality data communication environment can be obtained, and it is expected that it will be widely used in the future.

  Due to the above-described advantages, it is considered that a user who can use the femto cell service desires connection to the femto cell when entering the femto cell range from the macro cell range. As such a handoff method from a macro cell to a femto cell, a method using a pilot beacon is assumed. In order to avoid interference with the macro cell, the femtocell preferably uses a frequency different from that of the macro cell to avoid interference with the macro cell, but the pilot beacon, which is a signal used when the terminal searches for a base station, It is preferable to use the same frequency as that of the macro cell in order to draw the terminal in communication with the femto cell. In this case, in the femtocell, radio waves of two different frequencies, that is, a radio wave for communication and a pilot beacon are used. However, power consumption due to continuous transmission of these radio waves becomes a problem.

  As a countermeasure to this problem, the mobile phone terminal obtains its current location by GPS and compares the current location with a service area map showing the range that can be used by the mobile phone terminal. A technique for performing power control when outside the area has been proposed (see Patent Document 1).

Japanese Patent Laid-Open No. 11-186955

  In the femtocell, terminals connected to the own station are limited for the following reasons. First, since the network from the femtocell to the mobile communication network uses a dedicated line (femtocell user contracted line) that the user has contracted with, any terminal can be connected because of contractual and security problems. is there. In addition, a communication carrier (communication carrier) that provides a femtocell service may not allow connection of an unspecified number of terminals due to necessity of access control.

  For the above reason, it is assumed that only the terminal (registered terminal) registered as being able to use the own station can be used in the femtocell. In this case, since the femtocell is installed in a home or office, a situation in which no registered terminal exists in the femtocell area frequently occurs. In this situation, the femtocell does not need to transmit either communication radio waves or pilot beacons. Even if the registered terminal exists in the femtocell area, it is not necessary to transmit a pilot beacon except for the time when other registered terminals move to the femtocell area. In order to prevent unnecessary power consumption due to unnecessary transmission of radio waves, it is necessary to transmit radio waves for communication and pilot beacons only for an appropriate time.

  Further, the method described in Patent Document 1 is to grasp its own position by GPS and perform power control. However, it is not effective indoors where GPS cannot be used, and it is necessary to grasp by femtocell. Since there is a current position of a communication target terminal instead of its own position, even if the current position is regularly notified, power consumption occurs in communication for that purpose.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a base station and a base station control method capable of preventing wasteful power consumption due to unnecessary transmission of radio waves. There is to do.

  In order to achieve the above object, the present invention provides a base station of a mobile communication system, a transmitter for transmitting a pilot beacon for causing the mobile station to detect the mobile station, and a communication for communicating with the mobile station. A communication unit that transmits and receives radio waves, a registration unit that registers information on a mobile device that uses the mobile station or a user corresponding to the mobile device, and a mobile device that corresponds to the information registered in the registration unit When the mobile unit is not in the communicable area, the communication unit is configured not to transmit / receive the communication radio wave and to start transmission / reception of the communication radio wave when the mobile device is handing off to its own station. And a control unit for controlling.

  It is preferable that the control unit performs control so as to stop transmission of the pilot beacon when the handoff of the mobile device to the own station is completed.

  In addition, the present invention provides a receiving unit that receives a radio wave transmitted to another base station by a mobile device whose location is registered in another base station of the mobile communication system, and information registered in the registration unit. An acquisition unit that acquires a communication identifier of a mobile device corresponding to the other base station from a mobile communication network to which the other base station is connected, and the control unit stops transmission of the pilot beacon Then, when the communication identifier of the mobile device acquired by the acquisition unit is given from the other base station, the mobile device whose location is registered in the other base station by the receiving unit is The reception of radio waves to be transmitted to the other base station is started, and the communication identifier of the mobile device included in the radio waves with the intensity received by the reception unit equal to or higher than a threshold matches the communication identifier acquired by the acquisition unit. If the pie And controlling the transmission unit so as to resume the transmission of Ttobikon.

  The control unit receives radio waves transmitted from the mobile unit registered in the other base station to the other base station by the receiving unit when the handoff of the mobile unit to the own station is completed. Is preferably stopped.

  The present invention is also a method for controlling a base station of a mobile communication system, the step of transmitting a pilot beacon for causing the mobile station to detect the mobile station, and a communication radio wave for communicating with the mobile station. A step of transmitting and receiving; a step of registering information of a mobile device that uses the mobile station or a user corresponding to the mobile device; and a mobile device corresponding to the information registered in the registering step Including the step of not transmitting / receiving the communication radio wave and starting the transmission / reception of the communication radio wave when the mobile device is handing off to the own station when none of them are present. And

The present invention does not transmit communication radio waves when there is no registration terminal (mobile device) in the femtocell area, and transmits communication radio waves when the registration terminal (mobile device) is performing handoff. Therefore, useless transmission of radio waves for communication can be prevented and power saving can be achieved.
Further, according to the present invention, when the handoff of the registered terminal is completed, the pilot beacon transmission is stopped, so that unnecessary pilot beacon transmission can be prevented and power saving can be achieved.

1 is a schematic configuration diagram of a mobile communication system including a femto cell and a macro cell. It is a schematic block diagram of a femtocell. It is a flowchart which shows an example of a process when a femtocell starts the monitoring of the uplink communication of a terminal. It is a conceptual diagram when a femtocell management server notifies UATI of a registration terminal to a femtocell. It is a flowchart which shows an example of a process when a femtocell starts transmission of a pilot beacon. It is a conceptual diagram at the time of measuring the reception power of the signal of the uplink communication which the femtocell detected. It is a conceptual diagram when a femtocell decodes the signal of uplink communication. It is a conceptual diagram when a femtocell starts transmission of a pilot beacon. It is a flowchart which shows an example of the process of the femtocell when drawing a terminal in a femtocell. It is a sequence diagram between a terminal and a femtocell when drawing a terminal into a femtocell. It is a conceptual diagram when a femtocell pulls in a registration terminal by a pilot beacon. It is a conceptual diagram when a femtocell starts transmission of a femtocell radio wave (communication radio wave).

  Embodiments of the present invention will be described with reference to the drawings. In the following description, CDMA2000 1xEV-DO is assumed as the mobile communication system.

  FIG. 1 is a schematic configuration diagram of a mobile communication system including a femto cell and a macro cell. As shown in the figure, a mobile communication system 100 includes a macro cell (base station) AN, an EV-DO core network CN, a femto cell network gateway FNG, a wide area network NET, a femto cell FAP, and a plurality of terminals (mobile devices) AT1 to AT1. Includes AT3. The EV-DO core network CN is a backbone part of a mobile communication network including a PDSN (Packet Data Serving Node), a PCF (Packet Control Function), etc. (not shown). The femtocell network gateway FNG relays the connection between the wide area network NET and the EV-DO core network CN.

  In the mobile communication system 100, the macro cell AN transmits a macro cell radio wave having a frequency F1. Since the femtocell FAP draws (hands off) a terminal communicating with the macrocell AN to the femtocell, the femtocell FAP can transmit a pilot beacon having the same frequency F1 as the macrocell radio wave. The femtocell FAP itself uses femtocell radio waves (communication radio waves) of frequency F2 for communication between the own station and the terminal.

  Next, the femtocell FAP will be described. FIG. 2 shows a schematic block diagram of the femtocell FAP. As shown in the figure, the femtocell FAP includes an antenna ANT, a control unit 110 (control unit), a wireless communication unit 120, a storage unit 140, and a wired communication unit 150.

  The wireless communication unit 120 includes a pilot beacon transmission unit 122 (transmission unit), an uplink communication radio wave reception unit 124 (reception unit), and a terminal transmission / reception unit 126 (communication unit). The pilot beacon transmission unit 122 transmits a pilot beacon for drawing the terminal (mobile device) AT into the femtocell FAP. The uplink communication radio wave receiving unit 124 receives a radio wave (uplink communication radio wave) transmitted to the macro cell AN by a terminal (mobile device) AT whose location is registered in the macro cell AN (establishing a session). The terminal transmission / reception unit 126 transmits / receives femtocell radio waves (communication radio waves) for communicating with the terminal (mobile device) AT via the antenna ANT.

  The control unit 110 includes a pilot beacon transmission control unit 111, a femtocell radio wave transmission control unit 112, an uplink communication detection / determination unit 113, an uplink communication decoding unit 114, a registered terminal determination unit 115, a neighboring base station information acquisition unit 116, and terminal information. An acquisition unit 117 (acquisition unit), a UATI determination unit 118, and a pilot beacon transmission factor determination unit 119 are provided, and the entire femtocell FAP is controlled.

  The pilot beacon transmission control unit 111 controls the start and stop of pilot beacon transmission. The femtocell radio wave transmission control unit 112 controls transmission start / stop of the femtocell radio wave (communication radio wave). Uplink communication detection / determination section 113 detects and monitors uplink communication radio waves received by uplink communication radio wave reception section 124, and determines whether the intensity of the radio waves is equal to or greater than a threshold value. Uplink communication decoding section 114 decodes (decodes) an uplink communication signal determined by uplink communication detection / determination section 113 to have a strength equal to or greater than a threshold, and extracts a UATI (Unicast Access Terminal Identifier) included in the signal To do. The registered terminal determination unit 115 determines whether the UATI extracted by the uplink communication decoding unit 114 matches any of the UATIs of registered terminals notified from the femtocell management server or the macrocell AN in advance.

  The peripheral base station information acquisition unit 116 acquires information on the macro cell AN in the vicinity of the own station from a femto cell management server (not shown) existing in the EV-DO core network CN or by monitoring communication of the macro cell AN. . The information to be acquired is the information necessary to monitor the communication of the terminal connected to the macro cell AN (band class, channel, channel, PN (Pseudorandom Number) code, etc.) and the upstream communication signal of the terminal. Information (color code (ColorCode), sector ID (SectorID), etc.) necessary for the operation.

  The terminal information acquisition unit 117 supports the updated UATI and UATI of the registered terminal from the femtocell management server or the macrotocell AN in the EV-DO core network CN (mobile communication network) via the wired communication unit 150. ESN (Electric Serial Number) to be acquired. UATI and ESN will be described later. The UATI determination unit 118 compares the UATI acquired by the terminal information acquisition unit 117 with the color code acquired in advance from the surrounding macrotocell AN, and determines whether the UATI is acquired from the surrounding macrotocell AN. judge. The pilot beacon transmission factor determination unit 119 determines whether or not the ESN of the registered terminal handed off to the own station is the ESN of the terminal that has caused the pilot beacon transmission.

  The storage unit 140 includes a registered terminal storage unit 141, a neighboring base station information storage unit 142, a UATI storage unit 143, a pilot beacon transmission factor storage unit 144, and a threshold storage unit 145. The registered terminal storage unit 141 registers information on registered terminals, information on users (contractors and users of registered terminals) corresponding to registered terminals, and corresponding frequencies (such as band classes). For example, ESN can be used as terminal information registered in the own station. The ESN is a unique number (terminal identifier) possessed by the terminal. When the terminal is a mobile phone, it can be calculated from, for example, a telephone number. The user information corresponding to the registered terminal may be a user who can use the femtocell FAP and has a contract with a communication carrier that provides the femtocell FAP. When the user uses a plurality of terminals, the latter information is useful. Note that the terminal identifier is not limited to ESN, and an identifier other than ESN may be used as long as the femtocell can be acquired from the wide area network NET.

  The peripheral base station information storage unit 142 acquires information (band class, channel, PN code, etc.) necessary for monitoring the communication of the terminal connected to the macro cell AN acquired by the peripheral base station information acquisition unit 116, Information (color code, sector ID, etc.) necessary for decoding the uplink communication signal of the terminal is stored. The UATI storage unit 143 stores the UATI of the registered terminal notified from the femtocell management server or the macrotocell AN, and the ESN corresponding to the UATI. The pilot beacon transmission factor storage unit 144 stores the ESN of the terminal that has caused the pilot beacon transmission. The threshold value storage unit 145 stores a threshold value for the strength of the radio wave transmitted by the terminal connected to the macro cell AN.

  The wired communication unit 150 is connected to a wide area network NET such as the Internet via a router or a general line (a broadband line such as ADSL).

  Note that the femtocell FAP, for example, at the time of installation, when the installation location is changed, and / or at the time of registration of a terminal using its own station, the ESN of the registered terminal, the corresponding frequency (band class, etc.), and the femtocell FAP contract And the like are stored in the registered terminal storage unit 141. Such information may be directly input by the user via an operation input unit such as a keyboard (not shown) provided in the femtocell FAP, or the terminal may wirelessly transmit to the femtocell FAP.

  First, a process in which the femtocell FAP starts monitoring uplink communication of a terminal that communicates with the macrocell AN will be described. FIG. 3 is a flowchart illustrating an example of processing when the femtocell FAP starts monitoring uplink communication of a terminal. It is assumed that there is no registered terminal in the area of the femtocell FAP, and the femtocell FAP has stopped transmitting femtocell radio waves (communication radio waves) and pilot beacons. Further, every time the UATI of the registered terminal is updated, the femtocell management server or the macrotocell AN in the EV-DO core network CN transmits the UATI and the ESN corresponding to the UATI to the femtocell FAP via the wide area network NET. Shall be notified.

The femtocell FAP repeats loop 1 (steps S11 to S14) while monitoring the uplink communication of the terminal is stopped. When the terminal information acquisition unit 117 acquires the UATI of the registered terminal notified from the femtocell management server or the macrotocell AN and the ESN corresponding to the UATI via the wired communication unit 150 (step S12), the UATI determination unit 118 Then, the acquired UATI is compared with the color code acquired in advance from the neighboring macrotocel AN, and it is determined whether or not the UATI is obtained from the neighboring macrotocell AN (step S13). If it can be determined that the UATI is obtained from the surrounding macrotocell AN, the UATI determination unit 118 stores the notified UATI of the registered terminal and the ESN corresponding to the UATI in the UATI storage unit 143, and The communication detection / determination unit 113 starts monitoring uplink communication of a terminal that communicates with the macrotocell AN (step S15). The channel to be monitored at this time is determined based on information such as the corresponding frequency of the registered terminal acquired in advance, the band class of the neighboring macrotocel AN, the channel, the PN code, and the like.
If the registered terminal UATI and the ESN corresponding to the UATI are not notified from the femtocell management server or the macrotocell AN in step S12, the process proceeds to step S14, and the process of loop 1 is continued.

  FIG. 4 is a conceptual diagram when a femtocell management server (not shown) existing in the EV-DO core network CN notifies the femtocell FAP of the UATI of the registered terminal. As shown in FIG. 4, the macrotocell AN transmits radio waves at the frequency F1, and the femtocell FAP transmits neither femtocell radio waves (communication radio waves) nor pilot beacons. Each time the UATI of the registered terminal of the femtocell FAP is updated, the femtocell management server and the macrotocell AN in the EV-DO core network CN notify the femtocell FAP of the UATI and the ESN corresponding to the UATI. If the notified UATI represents a neighboring macrotocell AN, the femtocell FAP starts monitoring uplink communication of a terminal that communicates with the macrotocell AN.

  Next, processing in which the femtocell FAP starts transmission of pilot beacons will be described. FIG. 5 is a flowchart illustrating an example of processing when the femtocell FAP starts transmission of a pilot beacon. The femtocell FAP repeats loop 2 (steps S21 to S30) while stopping the transmission of the pilot beacon. First, the uplink communication detection / determination unit 113 uses the information stored in the neighboring base station information storage unit 142 described above to receive the uplink communication between the macro cell AN and the terminal received by the uplink communication radio wave reception unit 124. A communication signal is detected (step S22). When the uplink communication detection / determination unit 113 detects an uplink communication signal, the uplink communication detection / determination unit 113 measures the received power (step S23), and determines whether or not the threshold is greater than or equal to the threshold stored in the threshold storage unit 145 (step S23). Step S24).

  In the communication between the macro cell AN and the terminal AT, the transmission power of the terminal AT is normally controlled so that the reception power in the macro cell AN is substantially constant. Therefore, in the femtocell FAP, a constant value set in the macro cell AN. When a radio wave exceeding 1 is measured, the terminal AT that has transmitted the radio wave can be regarded as being located closer to the femtocell FAP than the macrocell AN. Therefore, the threshold stored in the threshold storage unit 145 is set to a constant value set in the macro cell AN. It should be noted that an area determined to be close to the femtocell FAP may be made narrower or wider by providing a certain margin from a certain value of the received power.

  The description of the flowchart of FIG. When it is determined in step S24 that the reception power of the radio wave received by the uplink communication radio wave reception unit 124 is equal to or greater than the threshold, the uplink communication decoding unit 114 stores the macro cell stored in the neighboring base station information storage unit 142. An attempt is made to decode the detected uplink communication signal using the AN information (step S25). If the decoding is successful (YES in step S26), the uplink communication decoding unit 114 attempts to extract the UATI of the terminal AT in communication with the macro cell AN from the decoding result (step S27). If the uplink communication decoding unit 114 succeeds in extracting the UATI (YES in step S28), the registered terminal determination unit 115 registers the extracted UATI from the femtocell management server or the macrotocell AN in advance. It is determined whether it matches any of the UATIs (step S29).

  Here, UATI is an identifier (communication identifier) temporarily assigned to a terminal connected to the base station (establishing a session with the base station). Therefore, the macro cell AN assigns UATI to a terminal that requests communication with the own station, and associates the assigned UATI with an ESN that is an identifier of the terminal.

  If it is determined in step S29 that the extracted UATI matches any of the UATIs of the registered terminals notified in advance from the femtocell management server or the macrotocell AN, the corresponding UATI is notified in advance. The ESN to be stored is stored in the pilot beacon transmission factor storage unit 144 as a pilot beacon transmission factor (step S31). Next, the pilot beacon transmission control unit 111 controls the pilot beacon transmission unit 122 to start pilot beacon transmission (step S32). In step S33, a timer for stopping the pilot beacon at a predetermined time is set (details will be described later).

  If no uplink communication is detected in step S22, if it is determined in step S24 that the reception power of the radio wave received by the uplink communication radio wave reception unit 124 is smaller than the threshold value, the uplink communication is decoded in step S26. If it is determined that it has failed, if UATI extraction has failed in step S28, or if it is determined in step S29 that the terminal AT in communication with the macro cell AN is not a registered terminal, the process proceeds to step S30. The processing of loop 2 is continued.

  The process flow in the flowchart of FIG. 5 will be described with reference to FIGS. FIG. 6 is a conceptual diagram when measuring the reception power of the uplink communication signal detected by the femtocell FAP. FIG. 7 is a conceptual diagram when the femtocell FAP decodes the uplink communication signal. FIG. 8 is a conceptual diagram when the femtocell FAP starts transmission of a pilot beacon. In FIG. 6, FIG. 7, and FIG. 8, the terminal AT1 is a registered terminal of the femtocell FAP. Further, it is assumed that the terminals AT1 to AT3 perform location registration (session establishment) with the macro cell AN. First, as illustrated in FIG. 6, when the femtocell FAP detects an uplink communication radio wave between the terminals AT1 to AT3 and the macrocell AN, the femtocell FAP determines its reception power. In the case of FIG. 6, it is determined that the received power of the radio wave received from the terminal AT1 is equal to or greater than the threshold value. If the received power is greater than or equal to the threshold, the femtocell FAP decodes the uplink communication signal and extracts the UATI assigned to the communication between the macrocell AN and the terminal AT1, as shown in FIG. If the UATI is for a registered terminal of the femtocell FAP, as shown in FIG. 8, the femtocell FAP transmits a pilot beacon for a certain period of time to pull in (handoff) the terminal AT1. The pilot beacon is transmitted at frequency F1.

Next, processing in which the femtocell FAP pulls in (hands off) the terminal will be described. FIG. 9 is a flowchart illustrating an example of processing performed by the femtocell FAP when the terminal is drawn into the femtocell FAP (handoff). FIG. 10 is a flowchart illustrating when the terminal AT is pulled into the femtocell FAP (handoff). It is a sequence diagram between AT and femtocell FAP.
In the flowchart of FIG. 9, the femtocell FAP repeats the process of loop 3 (steps S41 to S48) while transmitting the pilot beacon. First, when the femtocell FAP receives a UATI Request from the terminal AT during pilot beacon transmission (YES in step S42), the femtocell FAP starts a pull-in process (handoff process) for handing off the terminal AT to the femtocell FAP. (Step S43). The pull-in process of the terminal AT to the femtocell FAP starts when the terminal AT reacquires the femtocell FAP session.
The femtocell FAP in the present invention can perform a part of the pull-in process on the frequency of the pilot beacon, and transmits a Hardware ID Request before transmitting a Traffic Channel Assignment.

  When the pull-in process is started, the femtocell FAP transmits a HardwareID Request to the terminal AT (step S44, step P11 in FIG. 10), and receives a HardwareID Response from the terminal AT (step S45, step P11 in FIG. 10). ). The hardware ID is an identifier unique to the terminal, and includes ESN, MEID (Mobile Equipment Identifier) and the like.

  When receiving the Hardware ID Response, the pilot beacon transmission factor determination unit 119 determines whether or not the ESN included in the Hardware ID Response matches the ESN stored in the pilot beacon transmission factor storage unit 144 as the pilot beacon transmission factor. Is determined (step S46). The pilot beacon transmission factor is a factor for transmitting the pilot beacon stored in the pilot beacon transmission factor storage unit 144 when the femtocell FAP starts transmitting the pilot beacon as described with reference to the flowchart of FIG. This indicates the terminal that has become (step S31 in FIG. 5).

If the pilot beacon transmission factor determination unit 119 determines that the ESN included in the Hardware ID Response matches the ESN recorded as the pilot beacon transmission factor in step S46, the femtocell radio wave transmission control unit 112 The terminal transmission / reception unit 126 is controlled to start communication with cell radio waves (communication radio waves) (step S49). Next, the femtocell FAP transmits Traffic Channel Assignment to the terminal AT, and transitions the terminal AT to the channel of the femtocell FAP (step S50, step P12 in FIG. 10). When receiving the Traffic Channel Complete from the terminal AT (Step S51, Step P13 in FIG. 10), the femtocell FAP cancels the pilot beacon transmission timer (Step S52), stops the transmission of the pilot beacon (Step S56), The AT pull-in process is continued (step S57). Then, predetermined processing is performed between the terminal AT and the femtocell FAP until a session is established between the terminal AT and the femtocell FAP according to the EV-DO protocol (Session Configuration in FIG. 10). Further, the monitoring of uplink communication is stopped (step S58).
In step S51, if Traffic Channel Complete cannot be received from terminal AT, transmission of femtocell radio waves (communication radio waves) is stopped (step S53).

If a UATI Request is not received from the terminal AT in step S42, or if a HardwareIDResponse is not received from the terminal AT in step S45, the ESN included in the Hardware ID Response is a pilot beacon transmission factor in step S46. If the ESN stored in the storage unit 144 does not match, and if the transmission of the femtocell radio wave (communication radio wave) is stopped in step S53, it is determined whether the pilot beacon transmission timer has expired. If the pilot beacon transmission timer has not expired (step S47), the process proceeds to step S48, and the process of loop 3 is continued.
If the pilot beacon transmission timer expires in step S47, the timer is canceled (step S54) and the pilot beacon transmission is stopped (step S55). Thereafter, monitoring of uplink communication is stopped (step S58).

  Here, the pilot beacon transmission timer will be described. For example, it is conceivable that the terminal that has caused the transmission of the pilot beacon leaves the femtocell FAP area or turns off the power. If such a handoff to the femtocell FAP cannot be completed, it is not desirable to continue the pilot beacon transmission. Therefore, in loop 3, it is determined whether or not the pilot beacon transmission timer has expired (step S47). The pilot beacon transmission timer is set when the transmission of the pilot beacon is started in step S33 of FIG. In this way, even when the terminal that has caused the pilot beacon transmission becomes unable to handoff for some reason, the transmission of the pilot beacon can be stopped and the interference given to the macro cell AN can be suppressed.

  In step S46, if the ESN included in the Hardware ID Response does not match the ESN recorded as the pilot beacon transmission factor, the pilot beacon transmission factor determination unit 119 determines that the terminal corresponding to the ESN is This means that the femtocell FAP is another terminal that has moved to the area of the femtocell FAP while transmitting the pilot beacon. That is, “another terminal” is a terminal different from the terminal that causes the femtocell FAP to start transmitting a pilot beacon. Accordingly, the femtocell FAP continues to transmit pilot beacons (step S48). That is, the femtocell FAP does not stop the pilot beacon transmission unless the pull-in process with the terminal that has caused the pilot beacon transmission is performed. In this way, even when a plurality of registered terminals move from the area of the macro cell AN to the area of the femto cell FAP, each of the terminals can be surely handed off to the femto cell FAP.

  The femtocell FAP stops the detection (monitoring) of uplink communication in step S58, and then the registration terminal that has established the session with the femtocell FAP handoff and establishes the session with the macrocell AN. In order to hand off to the local station, it is necessary to resume detection of uplink communication radio waves. For that purpose, it is necessary to make the femtocell FAP recognize that the registered terminal has established a session in the macrocell AN. As this method, for example, it is possible to notify the femtocell FAP from the handoff registered terminal or the EV-DO core network CN. Further, the femtocell FAP may check a terminal that is waiting at its own station at regular intervals by using a keep alive function.

  The process flow in the flowchart of FIG. 9 will be described with reference to FIGS. 11 and 12. FIG. 11 is a conceptual diagram when the femtocell pulls in a registered terminal using a pilot beacon, and FIG. 12 is a conceptual diagram when the femtocell starts transmission of femtocell radio waves (communication radio waves). First, as shown in FIG. 11, the femtocell FAP draws the registered terminal to its own frequency F2 by a pilot beacon transmitted at the same frequency F1 as the macrotocell. When the registration terminal pull-in is completed, the femtocell FAP starts transmission of femtocell radio waves and stops transmission of pilot beacons as shown in FIG. The femtocell radio wave is transmitted at the frequency F2.

  The above-described embodiment is the one until the first registered terminal starts communication with the femtocell FAP. If the registered terminal already exists in the area of the femtocell FAP, the above-described embodiment It is assumed that the processing excluding the part related to the femtocell radio wave is performed.

As described above, the present invention does not transmit a communication radio wave when there is no registered terminal in the femtocell area, and starts transmitting a communication radio wave while the registration terminal is being drawn. It is possible to prevent wasteful transmission of radio waves and save power. The femtocell is expected to be mainly used for a limited time by a limited terminal in a home or a small office, and the time that the registered terminal exists in the femtocell area is limited. As a result, power consumption can be greatly reduced.
In addition, the present invention monitors the uplink communication of a terminal to a macrotocell, and starts transmission of a pilot beacon only when detecting uplink communication of a registered terminal whose received power is equal to or greater than a certain threshold, and Since the transmission of the pilot beacon is stopped when is completed, unnecessary pilot beacon transmission can be prevented and power saving can be achieved. Femtocells are expected to be mainly used in limited time with limited terminals in homes and small offices, and the time for registered terminals to move to the femtocell area is limited. The invention can greatly reduce power consumption.
Moreover, this invention can reduce interference with a macroto cell by suppressing transmission of the pilot beacon transmitted on the same frequency as a macroto cell as much as possible.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each unit, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of components, steps, etc. can be combined into one or divided. .

  The base station of the present invention starts transmission / reception of communication radio waves when the mobile device is handing off to the own station. In the above-described embodiment, when the mobile device is handing off to the own station, in step S46, if the ESN included in the Hardware ID Response matches the ESN recorded as the pilot beacon transmission factor, the pilot beacon transmission is performed. The case where it is determined by the factor determination unit 119 has been described as an example, but the base station of the present invention is not limited to this, and when the mobile device is handing off to the own station, for example, the terminal AT is The pull-in process (hand-off process) for handing off to the femtocell FAP may be started. After the pull-in process (hand-off process) is started in step S43, the mobile station is pulled into the femtocell frequency in step S50. Any time can be used until it is handed off.

DESCRIPTION OF SYMBOLS 100 Mobile communication system 110 Control part 111 Pilot beacon transmission control part 112 Femtocell radio wave transmission control part 113 Uplink communication detection / determination part 114 Uplink communication decoding part 115 Registered terminal determination part 116 Neighboring base station information acquisition part 117 Terminal information acquisition part 118 UATI determination unit 119 Pilot beacon transmission factor determination unit 120 Wireless communication unit 122 Pilot beacon transmission unit 124 Uplink communication radio wave reception unit 126 Terminal transmission / reception unit 140 Storage unit 141 Registered terminal storage unit 142 Peripheral base station information storage unit 143 UATI storage unit 144 Pilot beacon transmission factor storage unit 145 Threshold storage unit 150 Wired communication unit ANT antenna AT1 to AT3 terminal (mobile device)
AN macrocell (wide area base station)
CN EV-DO core network FNG femtocell network gateway NET wide area network FAP femtocell F1 macrocell radio wave, pilot beacon F2 femtocell radio wave (communication radio wave)

Claims (5)

A base station for a mobile communication system,
A transmission unit for transmitting a pilot beacon for causing the mobile station to detect its own station;
A communication unit for transmitting and receiving radio waves for communication to communicate with the mobile device;
A registration unit for registering information on a mobile device that uses the mobile station or a user corresponding to the mobile device;
When the mobile device corresponding to the information registered in the registration unit does not exist within its own communicable area, the mobile device does not transmit / receive the communication radio wave and the mobile device is performing a handoff to its own station A control unit that controls the communication unit to start transmission and reception of the communication radio wave;
A base station comprising:   The base station according to claim 1, wherein the control unit performs control so as to stop transmission of the pilot beacon when handoff of the mobile device to the own station is completed. In the base station according to claim 1 or 2,
A receiver that receives a radio wave transmitted to the other base station by a mobile device whose location is registered in another base station of the mobile communication system;
An acquisition unit for acquiring a communication identifier of a mobile device corresponding to information registered in the registration unit from a mobile communication network to which the other base station is connected;
Further comprising
The control unit is configured to stop the transmission of the pilot beacon, and when the communication identifier of the mobile device acquired by the acquisition unit is given from the other base station, the receiving unit Thus, the mobile device whose location is registered in the other base station starts receiving the radio wave transmitted to the other base station, and the mobile device whose intensity received by the receiving unit is included in the radio wave having a threshold value or more If the communication identifier matches the communication identifier acquired by the acquisition unit, the transmission unit is controlled to resume transmission of the pilot beacon.
A base station characterized by that.   The control unit receives radio waves transmitted from the mobile unit registered in the other base station to the other base station by the receiving unit when the handoff of the mobile unit to the own station is completed. The base station according to claim 3, wherein the base station is stopped. A control method for a base station of a mobile communication system, comprising:
Transmitting a pilot beacon for causing the mobile station to detect its own station;
Transmitting and receiving radio waves for communication to communicate with the mobile device;
A step of registering information of a mobile device using the mobile station or a user corresponding to the mobile device;
When no mobile device corresponding to the information registered in the registering step exists in its own communicable area, the mobile device does not transmit / receive the communication radio wave, and the mobile device performs handoff to its own station. Starting transmission / reception of the communication radio wave when performing,
A control method for a base station.

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