JP2010177922A - Base station and control method of base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for avoiding interference with communication between a microcell and a radio communication terminal by femtocells. <P>SOLUTION: A base station (100) of a mobile communication system includes: a connection portion (170) to which a radio communication terminal capable of communicating with a public base station (200) of the mobile communication system can be connected; and a control part (110) which makes the radio communication terminal (400) connected through the connection portion (170) start communicating with the public base station (200) when receiving a connection request for its station and makes the radio communication terminal (400) measure a state relating to radio communication with the public base station (200) and acquires measured first radio information from the radio communication terminal (400), makes the radio communication terminal (400) connected through the connection portion (170) start communicating with the public base station (200) when the communication started in response to connection request ends and makes the radio communication terminal (400) measure the state relating to the radio communication with the public base station (200) and acquires measured second radio information from the radio communication terminal (400), and determines whether there is interference with the public base station (200) based upon the first radio information and second radio information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In recent years, in mobile-to-communication systems, with the spread of broadband lines and the advancement of miniaturization technology for communication equipment, it covers a very small area called a femtocell compared to conventional wide-area base stations (public base stations, macrocells). Base stations are being developed. A femtocell is an ultra-small base station for subscribers installed in, for example, a house or a small office. The femtocell is connected to a mobile communication network via a general line (ADSL or other broadband line) drawn into each home. Connected. Because general lines are widely used as access lines, even users who are outside the macro cell area can use the same mobile phone service (call, mail function, SMS (Short Message Service), WEB browsing, etc. as long as there is a broadband line. Etc.) can be used inexpensively and easily.

  In addition, since it is desirable that the femtocell is used only by a terminal registered in advance, a dedicated femtocell can be occupied by a limited user. 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. With this background, the combination of outdoor public base stations and indoor femtocells will become essential in the 3rd generation (3G), 3rd generation (3.9G) and IMT-ADVANCED. is expected.

  Conventionally, in a macro cell, an efficient cell arrangement (cell design) that avoids radio wave interference between the macro cells is essential. Therefore, the communication carrier performs a simulation in advance using data such as topographic factors, transmission power, and use frequency, and performs cell design without radio wave interference. On the other hand, since femtocells are individually installed by subscribers of femtocells, the femtocell installation is subject to prior effects (interference, etc.) that may affect other base stations (femtocells and macrocells). Insufficient investigation. That is, the femtocell may cause radio wave interference to the macrocell.

  A specific example of such radio wave interference to the macro cell by the femto cell will be described with reference to the drawings. Hereinafter, a wireless communication terminal communicating with a femtocell is referred to as a “femtocell communication terminal”, and a wireless communication terminal communicating with a macrocell is referred to as a “macrocell communication terminal”. FIG. 9 is a diagram for explaining a case where communication between the macro cell communication terminal and the macro cell receives interference due to radio waves from the femto cell communication terminal. As shown in FIG. 9, the femtocell 100 is connected to a mobile communication network via a general line (broadband) NET. When a transmission signal (radio wave) transmitted from the femtocell communication terminal 300 to the femtocell 100 is received not only by the femtocell 100 but also by the macrocell 200, the radiowave becomes an interference wave for the macrocell 200. Due to this interference wave, the communication environment between the macro cell 200 and the macro cell communication terminal 500 is deteriorated.

  FIG. 10 is a diagram for explaining a case where communication between the macro cell communication terminal 500 and the macro cell is interfered by radio waves from the femto cell 100. For example, when a radio wave that hinders reception of spurious signals or the like is transmitted due to an internal failure of the femtocell 100, the radio wave becomes an interference wave for the macro cell communication terminal 500 in the vicinity of the femtocell 100. In addition, the radio wave itself from the femtocell 100 to the femtocell communication terminal 300 may be an interference wave. Due to this interference wave, the communication environment between the macro cell 200 and the macro cell communication terminal 500 is deteriorated.

  As a conventional technique for avoiding such radio wave interference, in a wireless LAN, a DFS (Dynamic Frequency Selection) function in which an available frequency band is dynamically selected, and transmission power are dynamically adjusted. There is a TPC (Traffic Power Control) function or the like (for example, see Patent Document 1).

JP 2007-274659 A

  Such a technique is not limited to wireless LANs, but is also being considered for use in femtocells for portable terminals. However, in these conventional techniques, communication is optimized only in a situation where the access point of the wireless LAN can identify itself using the reception function. That is, it cannot be determined whether or not radio waves from the access point of the wireless LAN actually interfere with surrounding communications. As described above, the communication carrier performs the simulation and optimally arranges the macro cells so that the radio wave environment with high quality can always be provided to the user. If the radio wave environment is affected by the femtocell, the convenience for the user is greatly impaired. However, in consideration of interference from femtocells, it is not a good idea to restrict the installation location or perform simulations in view of the nature of femtocells that can be freely installed. Therefore, the radio wave interference avoidance technique required for the femtocell is not only optimized for the communication of the femtocell itself as in the prior art, but also not to interfere with the macrocell.

  In addition, it is assumed that the femtocell is connected to a general line and the transmission power and the like are managed by the network operator's server on the network. However, if the number of femtocells increases, the server to be managed is loaded. . Therefore, it is necessary to reduce the management burden of the server.

  Accordingly, an object of the present invention is to detect interference by the base station (femtocell) itself to the communication between the public base station (macrocell) and the wireless communication terminal, and to avoid the interference. It is an object of the present invention to provide a base station (femtocell) and a base station control method.

In order to solve the above-described problems, a base station (femtocell) of a mobile communication system
A connection unit capable of connecting (wired or wirelessly) a wireless communication terminal capable of communicating with a public base station (macrocell) of the mobile communication system;
Upon receiving a connection request to the own station, the wireless communication terminal connected via the connection unit starts communication with the public base station (macro cell) to perform wireless communication with the public base station (macro cell). And measuring the first wireless information measured from the wireless communication terminal,
When the communication started in response to the connection request (with its own station) is completed, the wireless communication terminal connected via the connection unit starts communication with the public base station (macro cell). While measuring a state related to wireless communication with a base station (macro cell), obtaining the measured second wireless information from the wireless communication terminal,
And a control unit for determining presence or absence of interference with the public base station based on the first radio information and the second radio information.

In addition, a base station (femtocell) of a mobile communication system according to an embodiment of the present invention is
The controller is
The presence or absence of interference with the public base station is determined based on a transmission power difference between the wireless communication terminals included in the first wireless information and the second wireless information.

In addition, a base station (femtocell) of a mobile communication system according to another embodiment of the present invention is
The controller is
The presence or absence of interference with the public base station is determined based on a difference in modulation scheme when the wireless communication terminal communicates included in the first wireless information and the second wireless information.

A base station (femtocell) of a mobile communication system according to another embodiment of the present invention is:
The controller is
The presence or absence of interference with the public base station is determined based on a difference in reception quality of the wireless communication terminals included in the first wireless information and the second wireless information.

A base station (femtocell) of a mobile communication system according to another embodiment of the present invention is:
The controller is
If it is determined that there is interference with the public base station, the frequency band used by the own station is changed.

A base station (femtocell) of a mobile communication system according to another embodiment of the present invention is:
The controller is
When it is determined that there is interference with the public base station, control is performed so as to suppress transmission power of a wireless communication terminal communicating with the own station.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium that stores the program substantially corresponding to these, and the scope of the present invention. It should be understood that these are also included. In addition, each step of the following method and program uses an arithmetic processing unit such as a CPU or DSP as necessary in data processing, and the input data, processed / generated data, etc. are stored in the HDD, It is stored in a storage device such as a memory.

For example, a base station control method for a mobile communication system that implements the present invention as a method includes:
Connecting a wireless communication terminal capable of communicating with a public base station (macro cell) of the mobile communication system to a connection unit of the own station;
Upon receiving a connection request to the local station, the wireless communication terminal connected to the connection unit starts communication with the public base station (macro cell) in the connecting step, and the public base station (macro cell) Measuring a state related to wireless communication with the wireless communication terminal, and acquiring the measured first wireless information from the wireless communication terminal;
When the communication started in response to the connection request (with its own station) is completed, the wireless communication terminal connected to the connection unit starts communication with the public base station (macro cell) in the connecting step. And measuring the state related to wireless communication with the public base station (macro cell) and obtaining the measured second wireless information from the wireless communication terminal;
Determining whether or not there is interference with the public base station based on the first radio information and the second radio information.

  According to the present invention, the base station (femtocell) itself detects interference to the communication between the public base station (macrocell) and the wireless communication terminal by the base station (femtocell), and the base station that avoids the interference (Femtocell) and a base station control method can be provided.

It is a schematic block diagram of the base station (femtocell) of the mobile communication system by this invention. It is a schematic block diagram of a measurement terminal. 2 is a schematic diagram illustrating interference avoidance of a femtocell 100 according to an embodiment of the present invention. FIG. FIG. 10 is a schematic diagram when the macro cell communication terminal 500 of FIG. FIG. 11 is a schematic diagram when the macro cell communication terminal 500 of FIG. It is an example of the operation | movement flowchart of the measurement terminal 400. FIG. 3 is an example of an operation flowchart of the femtocell 100. 4 is a sequence diagram among femtocell communication terminal 300, femtocell 100, measurement terminal 400, and macrocell 200. FIG. It is a figure explaining the case where communication between a macrocell communication terminal and a macrocell receives interference by the electromagnetic wave from a femtocell communication terminal. It is a figure explaining the case where communication between a macrocell communication terminal and a macrocell receives interference by the electromagnetic wave from the femtocell.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic block diagram of a base station (femtocell) of a mobile communication system according to the present invention. Here, as a mobile communication system, the present invention can be applied to CDMA2000 1xEV-DO, W-CDMA system (HSDPA, etc.), LTE, and the like.

  As shown in FIG. 1, the femtocell 100 includes a control unit 110, an amplification unit 120, an RF (wireless) signal processing unit 130, a modulation unit 140, a GPS interface 150, a LAN interface 160, a measurement terminal connection unit 170, and an antenna ANT1. , ANT2. The antenna ANT1 transmits and receives radio waves for performing communication with the wireless communication terminal. The RF signal processing unit 130 performs front end processing for transmitting and receiving RF signals. Modulator 140 performs baseband processing for transmitting and receiving RF signals. The amplification unit 120 amplifies these transmission / reception signals. The GPS interface 150 performs time synchronization and position measurement of the femtocell 100 via the antenna ANT2. The LAN interface 160 is connected to a general line (a broadband line such as ADSL) via a router or the like. The measurement terminal connection unit 170 is connected to a measurement terminal described later. Note that the time synchronization and position measurement of the femtocell do not use GPS, but may receive a synchronization signal from a server via a broadband line, or the user of the femtocell 100 determines the installation position of the femtocell 100 in advance. You may register with the server. The control unit 110 controls these functional units and also performs various determination processes described later.

  Next, the measurement terminal will be described (details will be described later). FIG. 2 is a schematic block diagram of the measurement terminal. Measurement terminal 400 is a wireless communication terminal capable of communicating with a public base station (macro cell) of a mobile communication system. 2, the measurement terminal 400 includes a control unit 410, an amplification unit 420, an RF signal processing unit 430, a modulation unit 440, an input unit (button, touch panel, etc.) 450, a femtocell connection unit 460, a microphone MIC, and a speaker. SP and antenna ANT3 are provided. The antenna ANT3 transmits and receives radio waves for performing communication between the macro cell and the measurement terminal 400. The RF signal processing unit 430 performs front end processing for transmitting and receiving RF signals. Modulation section 440 performs baseband processing for transmitting and receiving RF signals. The amplifying unit 420 amplifies these transmission / reception signals. The microphone MIC, the speaker SP, and the input unit 450 are user interfaces of the mobile terminal. The femtocell connection unit 460 is connected to the measurement terminal connection unit 170 of the femtocell 100. The control unit 410 controls these functional units.

  Next, interference avoidance of the femtocell 100 according to an embodiment of the present invention will be described. As shown in FIGS. 9 and 10, when radio waves transmitted from the femtocell communication terminal 300 communicating with the femtocell 100 or the femtocell 100 itself interfere with communication between the macrocell 200 and the macrocell communication terminal 500. There is. In the present invention, such a situation is determined by the femtocell 100 itself, and an interference avoidance operation is performed by the femtocell 100.

  In general, in the mobile communication system, when the uplink radio wave from the macro cell communication terminal 500 becomes weak, the macro cell 200 transmits an instruction to maintain communication using, for example, a control channel or the like to the macro cell communication terminal 500. This instruction includes an increase in the transmission power of the macrocell communication terminal 500, a change to a modulation scheme with higher error resistance, and the like. Receiving the instruction, the macro cell communication terminal 500 changes the transmission power and the modulation method according to the instruction. That is, when interference is generated by the femtocell 100, some change occurs in communication between the macrocell 200 and the macrocell communication terminal 500. The present invention detects a change in radio state based on the above-described instruction between the macro cell 200 and the macro cell communication terminal 500, and determines whether or not a radio wave interference has occurred in the macro cell 200.

  This will be specifically described with reference to the drawings. FIG. 3 is a schematic diagram illustrating interference avoidance of the femtocell 100 according to one embodiment of the present invention. As shown in FIG. 3, in the present invention, a wireless communication terminal (measuring terminal) 400 capable of communicating with the macro cell 200 is connected to the femto cell 100 via a cable CB. Then, the measurement terminal 400 performs wireless communication with the macro cell 200 according to the control of the femto cell 100, and notifies the femto cell 100 of wireless information (modulation scheme, transmission power, etc.) with the macro cell 200. The femtocell 100 determines from the radio information broadcast from the measurement terminal 400 whether or not interference has occurred in the macrocell 200 due to communication based on the own station, and controls the communication of the own station so as to avoid the interference. . Thereby, the interference with respect to the macro cell 200 can be avoided by the femtocell 100 alone without using a server or the like.

  In other words, in the present invention, as shown in FIGS. 9 and 10, a macro cell communication terminal 500 in which communication with a macro cell is interfered is realized by the measurement terminal 400 in a pseudo manner. 4 and 5 show cases where the macro cell communication terminal 500 of FIGS. 9 and 10 is realized in a pseudo manner by the measurement terminal 400, respectively. As shown in the figure, the measurement terminal 400 and the femtocell 100 are connected to each femtocell connection unit 460 and the measurement terminal connection unit 170 by a cable CB. 4 and 5 show a mode in which the measurement terminal 400 is located in the vicinity of the cell boundary of the femtocell 100, the present invention is not limited to this. For example, the measurement terminal 400 may be brought close to the femtocell 100, and weighting may be performed in consideration of the distance between the macro cell 200 and the measurement terminal 400 when determining the presence or absence of interference described later.

  Next, interference avoidance of the femtocell 100 according to an embodiment of the present invention will be described using a flowchart and a sequence diagram. FIG. 6 is an operation flowchart of the measurement terminal 400, and FIG. 7 is an example of an operation flowchart of the femtocell 100. FIG. 8 is a sequence diagram among the femtocell communication terminal 300, the femtocell 100, the measurement terminal 400, and the macrocell 200.

  When the measurement terminal 400 is connected to the femtocell 100 through the femtocell connection unit 460, the measurement terminal 400 starts the flowchart illustrated in FIG. Control unit 410 determines whether or not there is a macro cell search instruction from femtocell 100 (step S11). If it is determined that there is an instruction, control unit 410 searches for a macro cell until it detects a macro cell whose location is to be registered (steps S12 and S13). If it is determined that there is a macro cell, the control unit 410 detects and reports a macro cell search result including information on the registered macro cell (step S14). After that, the measurement terminal 400 waits until there is a connection instruction from the femtocell 100 to the macrocell (step S15).

  When determining that there is a connection instruction from the femto cell 100 to the macro cell, the control unit 410 connects to the macro cell 200 (step S16). And the control part 410 measures the radio | wireless state between macrocells 200, and reports the information (radio information) regarding the measured radio | wireless state to the femtocell 100 (step S17). This measurement and reporting is repeated until there is a disconnection instruction from the femtocell 100 to the macrocell (step S18). If the control unit 410 determines in step S18 that there is an instruction to disconnect from the macro cell, in step S19, the connection to the cable CB, that is, the connection to the femto cell 100 via the femto cell connection unit 460 is released, in step S15. The process of S18 is repeated. In addition, you may loop from step S19 to step S11.

  Next, the operation of the femtocell 100 will be described. The femtocell 100 starts the flowchart illustrated in FIG. 7 in a state where the measurement terminal 400 is connected to the local station via the measurement terminal connection unit 170. First, the control unit 110 instructs the measurement terminal 400 to search for a macro cell (step S21). Then, the instruction is continued until the macro cell search result indicating that the macro cell is detected is received from the measurement terminal 400 (step S22). When the macro cell search result is received in step S22, the control unit 110 determines whether or not a connection request for the own station is received from the femtocell communication terminal (step S23). When it is determined in step S23 that there is a connection request, the control unit 110 determines whether or not the measurement terminal 400 is communicating with the macro cell 200 (step S24).

  If it is determined in step S24 that the measurement terminal 400 is not communicating with the macro cell 200, the control unit 110 instructs the measurement terminal 400 to connect to the macro cell and starts communication with the macro cell 200 (step S25). ). Furthermore, the control part 110 starts the timer with which an own station is provided (step S26). Thereafter, the control unit 110 controls the measurement terminal 400 to measure a state related to wireless communication between the measurement terminal 400 and the macro cell 200 until it is determined in step S28 that the timer has expired, and the measurement terminal The wireless information measured by 400 is acquired (received) as first wireless information (step S27). The radio information includes a transmission power of the measurement terminal 400, a control signal for controlling the transmission power of the measurement terminal 400 transmitted from the macro cell 200 to the measurement terminal 400, a modulation scheme used for the transmission of the measurement terminal 400, and the like. The measurement of the radio state between the macro cell 200 and the measurement terminal 400 during the communication between the femtocell 100 and the femtocell communication terminal 300 is referred to as “radio state measurement A”. If it is determined in step S24 that the measurement terminal 400 is communicating with the macro cell 200, the femtocell communication terminal that is different from the femtocell communication terminal that is determined to have a connection request in step S23. The wireless state measurement A is started. In this case, the influence of each femtocell communication terminal can be determined separately based on the log of the first wireless information in the wireless state measurement A (measurement time and wireless state are described).

  When the timer expires in step S28, the control unit 110 of the femtocell 100 instructs the measurement terminal 400 to disconnect from the macrocell 200 (step S29). Then, control unit 110 determines whether or not there is a disconnection request from the femtocell communication terminal that is communicating with the local station (step S30). When it is determined in step S30 that there is a disconnection request, control unit 110 determines whether or not measurement terminal 400 is communicating with macro cell 200 (step S32).

  If it is determined in step S32 that the measurement terminal 400 is not communicating with the macro cell 200, the control unit 110 instructs the measurement terminal 400 to connect to the macro cell, and starts communication with the macro cell 200 (step S32). ). Furthermore, the control part 110 starts a timer (step S33). Thereafter, the control unit 110 controls the measurement terminal 400 to measure a state related to wireless communication between the measurement terminal 400 and the macro cell 200 until it is determined in step S35 that the timer has expired. The wireless information measured by 400 is acquired (received) as second wireless information (step S34). The measurement of the radio state between the macro cell 200 and the measurement terminal 400 while the communication between the femtocell 100 and the femtocell communication terminal 300 is not performed is referred to as “radio state measurement B”. If it is determined in step S31 that the measurement terminal 400 is communicating with the macro cell 200, the femtocell communication terminal that is different from the femtocell communication terminal determined to be disconnected in step S30 is used. Wireless state measurement B (or A) is started. Also in this case, similarly to the wireless state measurement A, the influence of each femtocell communication terminal can be determined separately based on the log of the second wireless information (measurement time and wireless state are described).

  Thereafter, the control unit 110 instructs the measurement terminal 400 to disconnect from the macro cell 200 (step S35), and the femtocell 100 determines from the first radio information and the second radio information acquired in the radio state measurements A and B, respectively. It is determined whether or not interference is given (step S37).

  Here, determination of presence / absence of interference will be described. For example, a case where determination is performed using the transmission power of the measurement terminal 400 will be described. In this case, the average transmission power TxaveB in the wireless state measurement B where communication between the femtocell communication terminal 300 and the femtocell 100 is not performed, and the wireless state measurement during the communication between the femtocell communication terminal 300 and the femtocell 100 are performed. The average transmission power at A is compared with TxaveA. When the difference between these average transmission powers is equal to or greater than a predetermined threshold Txdiff, the measurement terminal 400 increases the transmission power during the communication between the femtocell communication terminal 300 and the femtocell 100, that is, the femtocell I have received interference. Therefore, it is determined that interference occurs when the following expression is satisfied.

  Further, the reception quality (SIR: Signal to Interference power Ratio) of the measurement terminal 400 can also be used to determine the presence or absence of interference. In this case, the average reception quality SIRaveB in the wireless state measurement B in which communication between the femtocell communication terminal 300 and the femtocell 100 is not performed, and the wireless state measurement in which the femtocell communication terminal 300 and the femtocell 100 are communicating. The average reception quality S in A is compared with SIRaveA. When the difference between these average reception qualities is equal to or greater than a predetermined threshold SIRdiff, the reception quality of the measurement terminal 400 has deteriorated during the communication between the femtocell communication terminal 300 and the femtocell 100, that is, interference of the femtocell. It will be received. Therefore, it is determined that interference occurs when the following expression is satisfied.

  If it is determined in step S37 that there is interference by the process as described above, the control unit 110 performs a process of controlling the own station to avoid interference (step S38). That is, the femtocell 100 avoids interference by changing the frequency band used by the femtocell 100 or suppressing the transmission power of the wireless communication terminal communicating with the own station.

  The determination of the presence / absence of interference is not limited to the above, and may be performed based on the difference in SNR (Signal to Noise power Ratio) of the measurement terminal 400 and the modulation method. In the latter case, for example, when the modulation scheme in the radio condition measurement A has a higher error correction capability than the modulation scheme in the radio condition measurement B, it is determined that interference by the femtocell 100 has occurred. The

  Next, a description will be given using a sequence diagram. FIG. 8 is a sequence diagram among femtocell communication terminal 300, femtocell 100, measurement terminal 400, and macrocell 200. First, the measurement terminal 400 is in a standby state for the macro cell 200 through steps S11 to S14 of FIG. Here, the femtocell communication terminal 300 transmits a connection request to the femtocell 100 (step T11). In response to the connection request, the femtocell 100 instructs the measurement terminal 400 to start connection to the macrocell 200 (step T12). Receiving the connection start instruction, the measurement terminal 400 connects to the macro cell 200 (step T13), and communication is established between the measurement terminal 400 and the macro cell 200 (step P11). Communication is also established between the femtocell communication terminal 300 and the femtocell 100 (step P12). In this state, the femtocell 100 controls the measurement terminal 400 to measure the state related to the wireless communication between the measurement terminal 400 and the macro cell 200, and the wireless information measured by the measurement terminal 400 is transmitted to the first wireless device. Obtained as information (radio state measurement A, step S27). That is, the measurement terminal 400 periodically reports the radio state with the macro cell 200 to the femto cell 100 (radio information reporting steps T14 and T15). Thereafter, when the timer expires, the control unit 110 of the femtocell 100 instructs the measurement terminal 400 to disconnect from the macrocell 200 (step T16). Receiving the disconnection instruction, the measurement terminal 400 disconnects communication with the macro cell 200 (step T17) and enters a standby state (step P13).

  Thereafter, the femtocell communication terminal 300 transmits a disconnection request to the femtocell 100 (step T18). When receiving the disconnection request from the femtocell communication terminal 300, the femtocell 100 instructs the measurement terminal 400 to connect to the macrocell 200 and starts communication with the macrocell 200 (step T19). Receiving the connection start instruction, the measurement terminal 400 connects to the macro cell 200 (step T20), and communication is established between the measurement terminal 400 and the macro cell 200 (step P15). Further, the femtocell communication terminal 300 enters a standby state (step P14). In this state, the femtocell 100 controls the measurement terminal 400 to measure the state related to the wireless communication between the measurement terminal 400 and the macro cell 200, and the radio information measured by the measurement terminal 400 is transmitted to the second radio. Obtained as information (radio state measurement B, step S34). That is, the measurement terminal 400 periodically reports the radio state with the macro cell 200 to the femto cell 100 (radio information reporting steps T21 and T22). Thereafter, when the timer expires, the control unit 110 of the femtocell 100 instructs the measurement terminal 400 to disconnect from the macrocell 200 (step T23). Receiving the disconnection instruction, the measurement terminal 400 disconnects communication with the macro cell 200 (step T24) and enters a standby state (step P16). Thereafter, the femtocell 100 determines the presence or absence of interference (step S37 in FIG. 7). If it is determined that there is interference, an interference avoidance process is performed (step S38 in FIG. 7).

  As described above, according to the present invention, the femtocell can acquire the state of wireless communication between the macrocell and the wireless communication terminal from the wireless communication terminal that performs communication with the macrocell. Therefore, the influence of the femtocell between the macrocell and the wireless communication terminal in communication with the macrocell, or the influence of the wireless communication terminal in communication with the femtocell between the macrocell and the wireless communication terminal in communication with the macrocell. The femtocell itself can determine how the state of wireless communication with the macrocell has changed. Therefore, the femtocell can be controlled in accordance with the surrounding environment as compared with the prior art.

  In the above-described embodiment, the period during which the wireless state is measured is determined by the timer. However, the present invention is not limited to this, and measurement is performed until there is a disconnection request or a connection request from the femtocell communication terminal 300. May be continued. Since the macro cell arrangement does not change frequently, the interference avoidance processing by the femto cell as described above is performed at the initial setting of the femto cell, that is, at the time of installation, and the femto cell and the femto cell communication set by the interference avoidance processing are performed. Subsequent operations may be performed according to the transmission power and operating frequency of the terminal. Then, when the installation of a new macro cell is notified from the server, when the installation position of the femto cell itself is changed, or when based on a user operation, the above-described interference avoidance process may be newly performed. Or you may carry out periodically like once a week and once a month.

  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 that there is no logical contradiction, and a plurality of components, steps, etc. can be combined or divided into one. . For example, in the above-described embodiment, the aspect in which the measurement terminal 400 and the femtocell 100 are connected by wire has been described. However, the present invention is not limited thereto, and may be connected wirelessly.

100 base station (femtocell)
DESCRIPTION OF SYMBOLS 110 Control part 120 Amplification part 130 RF signal processing part 140 Modulation part 150 GPS interface 160 LAN interface 170 Measurement terminal terminal connection part 200 Public base station (macrocell)
300 Femtocell communication terminal (wireless communication terminal)
400 Measuring terminal (wireless communication terminal)
410 control unit 420 amplification unit 430 RF signal processing unit 440 modulation unit 450 input unit 460 femto cell connection unit 500 macro cell communication terminal ANT1, ANT2, ANT3 antenna MIC microphone SP speaker

Claims (7)

A base station for a mobile communication system,
A connection unit capable of connecting a wireless communication terminal capable of communicating with a public base station of the mobile communication system;
Upon receiving a connection request to the own station, the wireless communication terminal connected via the connection unit starts communication with the public base station and measures a state related to wireless communication with the public base station. , Acquiring the measured first wireless information from the wireless communication terminal,
When the communication started in response to the connection request is completed, the wireless communication terminal connected via the connection unit starts communication with the public base station, and the state regarding the wireless communication with the public base station is determined. And measuring the second wireless information measured from the wireless communication terminal,
A control unit for determining presence or absence of interference with the public base station based on the first radio information and the second radio information;
A base station comprising: In the base station according to claim 1,
The controller is
Based on a transmission power difference between the wireless communication terminals included in the first wireless information and the second wireless information, the presence or absence of interference with the public base station is determined.
A base station characterized by that. In the base station according to claim 1,
The controller is
Determining the presence or absence of interference with the public base station based on a difference in modulation scheme when the wireless communication terminal included in the first wireless information and the second wireless information communicates;
A base station characterized by that. In the base station according to claim 1,
The controller is
Determining the presence or absence of interference with the public base station based on a difference in reception quality of the wireless communication terminal included in the first wireless information and the second wireless information;
A base station characterized by that. In the base station according to any one of claims 1 to 4,
The controller is
When it is determined that there is interference with the public base station, the frequency band used by the own station is changed.
A base station characterized by that. In the base station according to any one of claims 1 to 4,
The controller is
When determining that there is interference with the public base station, control to suppress the transmission power of the wireless communication terminal that is communicating with the own station,
A base station characterized by that. A control method for a base station of a mobile communication system, comprising:
Connecting a wireless communication terminal capable of communicating with a public base station of the mobile communication system to a connection unit of the own station;
When a connection request is received with respect to the local station, the wireless communication terminal connected to the connection unit in the connecting step starts communication with the public base station, and a state relating to wireless communication with the public base station Measuring the first wireless information from the wireless communication terminal, and
When the communication started in response to the connection request is completed, the wireless communication terminal connected to the connection unit is started to communicate with the public base station in the connecting step, and wireless communication with the public base station is performed. Measuring a state related to communication and obtaining the measured second wireless information from the wireless communication terminal;
Determining whether there is interference with the public base station based on the first radio information and the second radio information;
A control method for a base station.

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