JP2012060403A - Mobile radio terminal apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile radio terminal apparatus that can efficiently detect femtocells.SOLUTION: In an embodiment, the mobile radio terminal apparatus capable of radio communication with a macro base station and with a femto base station forming a femtocell overlapping a macro cell formed by the macro base station includes: storage means for associatively storing identification information about the macro base station and the femto base station having overlapping cells; detection means for detecting the received power level of a received signal; and search means for, if the received power level of a radio signal transmitted from the macro base station whose identification information is stored in the storage means satisfies a preset condition, searching for the femto base station whose identification information is associated with the macro base station.

Description

  Embodiments described herein relate generally to a mobile radio terminal device such as a mobile phone.

As is well known, the next-generation mobile radio communication system OFDMA (Orthogonal Frequency Division Multiple Access) is used as a radio access scheme, standardization is advanced by 3GPP (3 ^rd Generation Partnership Project) is a standardization organization of mobile communication technology ing.

  In the next-generation mobile radio communication system, in addition to a macro cell covering a wide area, a small cell (Femto Cell) base station covering a small zone area of several tens of meters such as homes, offices, and restaurants. Installation of equipment is considered. By installing femtocells, it is possible to complement out-of-service points such as shadowing, cover for environments where radio waves are blocked, such as indoors, and services in areas where traffic is concentrated such as event venues and stations.

  A femtocell called a femtocell HGW (Home GateWay) or CSG (Closed Service Group) cell is installed indoors so that a specific user can use it. When a terminal device that can use this type of femtocell enters the cover area, it is desirable to connect with priority over the femtocell even if it can receive radio waves from the macrocell.

  However, the coverage area of the femtocell is very small compared to the coverage area of the macrocell. For this reason, in order for a terminal device to connect preferentially to a femtocell, the search operation is repeated, resulting in an increase in power consumption.

JP 2008-278264 A

In the conventional mobile radio terminal apparatus, there is a problem that power consumption increases when the search operation is repeated in order to preferentially connect to the femtocell.
An object of the present invention is to solve this problem and provide a mobile radio terminal device capable of efficiently detecting a femto cell.

  According to an embodiment, in a mobile radio terminal apparatus capable of wireless communication with a macro base station and a femto base station that forms a femto cell that overlaps a macro cell formed by the macro base station, the macro base station and the femto that overlap each other Storage means for storing both identification information of the base station in association with each other, detection means for detecting the reception power level of the received signal, and reception power level of the radio signal transmitted from the macro base station in which the storage means stores the identification information However, when a preset condition is satisfied, a search means for searching for a femto base station whose identification information is associated with the macro base station is provided.

1 is a circuit block diagram showing a configuration of a mobile phone according to an embodiment. FIG. 2 is a circuit block diagram illustrating a configuration of a reception system of the mobile phone illustrated in FIG. 1. The figure which shows an example of the information which the femtocell search trigger information storage part shown in FIG. 2 memorize | stores. 6 is a flowchart for explaining the operation of the mobile phone according to the embodiment. The figure which illustrated arrangement | positioning of a macrocell and a femtocell.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of a mobile phone according to the embodiment. As shown in FIG. 1, the cellular phone includes a main control unit 100, a radio communication unit 10, a display unit 20, a call unit 30, an operation unit 40, and a storage unit 50 as main components. And a function of performing communication via the base station apparatus BS forming the macro cell and the mobile communication network MNW, and performing communication via the access point AP forming the femto cell and the public network PNW such as the Internet.

  The radio communication unit 10 performs radio communication with, for example, an OFDM (Orthogonal Frequency Division Multiplexing) system with the base station apparatus BS or the access point AP in accordance with an instruction from the main control unit 100. Audio data and e-mail data are transmitted and received, and Web data and streaming data are received.

  The display unit 20 displays images (still images and moving images), character information, and the like under the control of the main control unit 100, and visually transmits information to the user. Information to show is also displayed.

The call unit 30 includes a speaker 31 and a microphone 32, converts user's voice input through the microphone 32 into voice data that can be processed by the main control unit 100, and outputs the voice data to the main control unit 100, or a wireless communication unit. 10 is to decode the audio data received by 10 and output from the speaker 31.
The operation unit 40 includes a plurality of key switches and the like, and receives instructions from the user through this.

  The storage unit 50 includes a control program and control data of the main control unit 100, application software, address data that associates the name and telephone number of the communication partner, transmitted / received e-mail data, Web data downloaded by Web browsing, The downloaded content data is stored, and streaming data and the like are temporarily stored. The storage unit 50 includes one or more storage units such as an HDD, a RAM, a ROM, and an IC memory.

  The main control unit 100 includes a microprocessor, operates according to a control program stored in the storage unit 50, and controls the respective units of the mobile phone. The main control unit 100 performs voice communication and data through the wireless communication unit 10. In order to perform communication, a network communication control function for controlling each part of the communication system, an application processing function, and a femto cell search function are provided.

  The application processing function is performed by the main control unit 100 operating according to application software stored in the storage unit 50, for example, transmission / reception of e-mails, Web browsing, shooting with a digital camera (not shown), infrared, Bluetooth (registered trademark) Perform near field communication such as.

  The main control unit 100 also has an image processing function for displaying video on the display unit 20 based on image data (still image data or moving image data) such as received data or downloaded streaming data. In the image processing function, the main control unit 100 decodes the image data, performs image processing on the decoding result, and displays an image on the display unit 20.

Next, the femto cell search function will be described with reference to FIG.
FIG. 2 mainly shows a configuration related to femto cell search, that is, access point AP search.

  The radio communication unit 10 includes a radio unit 11, a demodulation unit 12, a rate conversion unit 13, a decoding unit 14, and an RSSI (Received Signal Strength Indicator) measurement unit 15. 2 shows only the configuration of the reception system, the radio communication unit 10 includes a configuration of a transmission system for generating an OFDM modulated signal from received data.

The main control unit 100 includes an error correction processing unit 101, a received data processing unit 102, a cell ID detection unit 103, a femto cell search control unit 104, a data communication detection unit 105, and a reselection / handover control unit. 106.
The storage unit 50 includes a femtocell search trigger information storage unit 51.

  The radio unit 11 obtains a baseband signal by down-converting the radio signal transmitted from the base station apparatus BS or the access point AP with respect to the frequency indicated by the main control unit 100.

  The demodulator 12 performs OFDM demodulation on the baseband signal. Specifically, quadrature detection, A / D conversion, secondary demodulation (fast Fourier transform), primary demodulation (demodulation such as QPSK and 16QAM) Etc.

The rate conversion unit 13 performs rate conversion (depuncturing or the like) on the demodulation result of the demodulation unit 12 according to the coding rate.
The decoding unit 14 decodes the conversion result of the rate conversion unit 13.

  The RSSI measurement unit 15 measures the received power level from the baseband signal in accordance with an instruction from the main control unit 100 and outputs the measurement result to the main control unit 100. The RSSI measurement by the RSSI measurement unit 15 is repeatedly executed at a preset period.

The error correction processing unit 101 detects an error from the decoding result of the decoding unit 14, performs error correction processing as necessary, and obtains received data.
The reception data processing unit 102 identifies a frame configuration for the reception data obtained by the error correction processing unit 101.

  From the processing result of the received data processing unit 102, the cell ID detection unit 103 determines the ID of the cell to which the base station device BS or access point AP that is the transmission source of the radio signal received by the mobile phone belongs (hereinafter referred to as cell ID). Is detected).

  The femto cell search control unit 104 reads the femto cell search trigger information associated with the cell ID detected by the cell ID detection unit 103 from the femto cell search trigger information storage unit 51, and controls the radio communication unit 10 according to this information. The femto cell (femto HGW) is searched. When a predetermined condition is satisfied, the reselection / handover control unit 106 is controlled to execute cell reselection and handover.

  Note that the femto cell search trigger information is data generated when waiting for an incoming call in the past, and as shown in FIG. 3, the femto cell search trigger information TD1 to TDn exists in the macro cell ID in the cover area. ID of the femtocell (hereinafter referred to as femtocell ID), information on the center frequency of the femtocell (hereinafter referred to as center frequency information), information indicating the synchronization timing of the femtocell (hereinafter referred to as synchronization timing information) ), RSSI information indicating the RSSI of the macro cell measured when leaving the femto cell, and another macro cell that transmits a reference signal that can be received by the mobile phone when the femto cell is used (hereinafter referred to as an adjacent macro cell) Information (hereinafter referred to as adjacent cell ID) and the like.

  In the following description, as RSSI information, as described above, it is assumed that the macro cell RSSI measured when leaving the femto cell is used. However, the RSSI information is not limited to this, and when connecting to the femto cell, The measured macro cell RSSI or the macro cell RSSI measured while connected to the femto cell may be used.

The data communication detection unit 105 monitors a transmission system (not shown) and determines whether data communication is being performed.
The reselection / handover control unit 106 executes cell reselection and handover according to an instruction from the femtocell search control unit 104.

  Next, the operation of the mobile radio terminal apparatus having the above configuration will be described with reference to FIG. FIG. 4 is a process executed by the femtocell search control unit 104 when the location registration is performed on the macro cell to which the base station device BS belongs through the base station device BS and the incoming call waiting is performed. It is executed repeatedly until The control program and control data are stored in the storage unit 50, and the femtocell search control unit 104 is realized by the main control unit 100 operating according to the control program and control data.

  The incoming call waiting is a state in which a substantial paging signal for notifying an incoming call is periodically received from the macro cell although substantial data communication is not performed. The macro cell is detected by receiving the synchronization signal transmitted from the macro cell to detect the used frequency and the synchronization timing, and further obtaining the correlation between the received synchronization signal and the ID patterns of a number of macro cells prepared in advance. To do.

  First, in step 4a, the femto cell search control unit 104 obtains the cell ID of the macro cell used for waiting for an incoming call from the cell ID detection unit 103, and uses the femto cell search trigger information including the cell ID as the femto cell search trigger information. The storage unit 51 is read. Then, it is determined whether or not the read femtocell search trigger information includes a femtocell ID.

  That is, it is determined from the femto cell search trigger information stored in the femto cell search trigger information storage unit 51 whether or not there is a femto cell that can be used by the mobile phone in the macro cell used for waiting for an incoming call. Here, in the case of the cell ID of the macro cell in which the femto cell is set, the process proceeds to step 4c. On the other hand, in the case of the cell ID of the macro cell in which the femto cell is not set, the process proceeds to step 4b.

  In step 4b, the femtocell search control unit 104 determines whether or not the macro cell used for incoming call waiting has changed under the control of the main control unit 100. Here, when the macro cell used for waiting for an incoming call is changed, the process proceeds to step 4a. On the other hand, when the change does not occur, the monitoring is continued again at step 4b.

  Note that the change of the macro cell used for waiting for an incoming call is determined based on, for example, the measurement result of the RSSI measuring unit 15 and other macro cells are in a better communication environment than the macro cell currently used for waiting for an incoming call. In some cases, this is done by the main control unit 100. This can be realized by a well-known handover technique.

In step 4c, the femto cell search control unit 104 determines whether or not the adjacent cell ID is included in the femto cell search trigger information read in step 4a.
That is, the femtocell search trigger information storage unit 51 determines whether or not there is an adjacent macrocell that transmits a reference signal that can be received by the mobile phone when using the femtocell existing in the macrocell used for waiting for an incoming call. Judgment is made based on whether or not the adjacent cell ID is included in the stored femtocell search trigger information. If an adjacent macro cell is set for the cell ID, the process proceeds to step 4g. On the other hand, if an adjacent macro cell is not set for the cell ID, the process proceeds to step 4d.

  In step 4d, the femtocell search control unit 104 determines an RSSI determination value based on the RSSI information included in the femtocell search trigger information read in step 4a, and proceeds to step 4e. The RSSI information may be used as it is as the RSSI determination value.

In step 4e, the femtocell search control unit 104 acquires a plurality of measurement results continuously measured by the RSSI measurement unit 15 and proceeds to step 4f.
In step 4f, the femtocell search control unit 104 determines whether or not the plurality of measurement results acquired in step 4e have changed beyond the RSSI determination value determined in step 4d. That is, it is determined whether or not the plurality of measurement results acquired in step 4e have changed across the RSSI determination value determined in step 4d from bottom to top or from top to bottom. Here, if the value has changed beyond the RSSI determination value, the process proceeds to step 4k. On the other hand, if the value has not changed, the process proceeds to step 4e to determine the next consecutive sample.

  Thereby, it is possible to determine whether or not the mobile phone is likely to be in the cover area of the femtocell. Because, when there is a high possibility of being in the coverage area of the femtocell, the RSSI measurement result is likely to fluctuate from the RSSI judgment value based on the RSSI information measured when leaving the femtocell in the past Because.

  Here, a description will be given with reference to the example of FIG. In this example, it is assumed that the mobile phone MS1 has moved into the femtocell FC1 formed by the access point AP1 installed at home, for example, when the user returns home. It is assumed that the access point AP1 is installed in the macro cell MC1 formed by the base station device BS1 and cannot receive radio signals from other base station devices BS2.

  The mobile phone MS1 detects that it is in the macro cell MC1, refers to the femto cell search trigger information associated with the cell ID of the macro cell MC1, and the femto cell FC1 is set in this information (Yes in step 4a). Then, it is detected that the adjacent cell ID is not set (No in step 4c).

  Then, an RSSI judgment value based on the RSSI information measured when leaving the femtocell FC1 in the past is acquired (step 4d), and it is detected that the current RSSI measurement result fluctuates with this RSSI judgment value as a boundary. (Steps 4e and 4f). As a result, it was confirmed that the mobile phone MS1 is in a concentric circle with the radius between the base station device BS1 and the access point AP1 centered on the base station device BS1, and again in the femtocell FC1. There is a high possibility of being there.

  On the other hand, the mobile phone MS0 detects that it is in the macro cell MC1, refers to the femto cell search trigger information associated with the cell ID of the macro cell MC1, and the femto cell FC1 is set in this information ( It is detected that the adjacent cell ID is not set (No in Step 4c).

  Similarly, the RSSI determination value based on the RSSI information measured when leaving the femtocell FC1 in the past is acquired (step 4d), but the current RSSI measurement result does not vary with this RSSI determination value as a boundary. Is detected (steps 4e and 4f). That is, it is confirmed that the mobile phone MS1 is not on the concentric circle, and there is a high possibility that the mobile phone MS1 has not yet moved into the femtocell FC1.

  In the above description, the determination is made based on whether or not the measurement result has changed beyond the RSSI determination value, but instead of this, or in addition to this, for example, a plurality of measurement results indicate the RSSI determination value. It is determined whether or not to transition within a predetermined range as a reference, and when the transition is within the predetermined range, the process proceeds to step 4k. On the other hand, when the transition does not occur, the process proceeds to step 4e. Good.

  In step 4g, the femtocell search control unit 104 determines an RSSI determination value based on the RSSI information included in the femtocell search trigger information read in step 4a, and proceeds to step 4h. The RSSI information may be used as it is as the RSSI determination value.

In step 4h, the femtocell search control unit 104 acquires a plurality of measurement results measured continuously in time by the RSSI measurement unit 15, and proceeds to step 4i.
In step 4i, the femtocell search control unit 104 determines whether or not the plurality of measurement results acquired in step 4h have changed beyond the RSSI determination value determined in step 4g. As in step 4f, this determination is made as to whether or not the plurality of measurement results acquired in step 4e have changed across the RSSI determination value determined in step 4d from bottom to top or from top to bottom. judge. Here, if the value has changed beyond the RSSI determination value, the process proceeds to step 4j. On the other hand, if not changed, the process proceeds to step 4h to determine the next consecutive sample.

  As in step 4f, instead of or in addition to the above determination, for example, it is determined whether or not a plurality of measurement results transition within a predetermined range based on the RSSI determination value. If the transition is within the predetermined range, the process may proceed to step 4j. If the transition is not performed, the process may proceed to step 4h.

  In step 4j, the femtocell search control unit 104 controls the radio communication unit 10 to try to receive the adjacent cell ID from the macrocell of the adjacent cell ID included in the femtocell search trigger information read in step 4a. Here, when the adjacent cell ID can be received, the process proceeds to step 4k. On the other hand, when the adjacent cell ID cannot be received, the process proceeds to step 4h, and the next consecutive sample is determined.

  Thereby, it is possible to determine whether or not the mobile phone is likely to be in the cover area of the femtocell. This is because, when there is a high possibility of being in the coverage area of the femtocell, the neighboring cell ID has been received in the past.

  Here, a description will be given with reference to the example of FIG. In this example, for example, it is assumed that the mobile phone MS2 has moved into the femtocell FC2 formed by the access point AP2 installed in the user's home when the user returns home or the like. The access point AP2 is installed near the boundary between the macro cell MC1 formed by the base station device BS1 and the macro cell MC2 formed by the base station device BS2, and radio signals are received from both the base station device BS1 and the base station device BS2. It shall be receivable. In other words, it is assumed that the femtocell FC2 is formed in a region where the macrocell MC1 and the macrocell MC2 overlap.

  The mobile phone MS2 detects that it is in the macro cell MC1 formed by the base station device BS1, refers to the femto cell search trigger information associated with the cell ID of the macro cell MC1, and the femto cell FC1 sets this information. (Yes in step 4a), and it is detected that the neighbor cell ID is set (Yes in step 4c).

  Then, the RSSI judgment value based on the RSSI information measured when leaving the femtocell FC1 in the past is obtained (step 4g), and it is detected that the current RSSI measurement result fluctuates with this RSSI judgment value as a boundary. (Steps 4h, 4i). As a result, it was confirmed that the mobile phone MS2 is on a concentric circle with the radius between the base station device BS1 and the access point AP1 centered on the base station device BS1, and again in the femtocell FC2. There is a high possibility of being there.

  Further, since the neighbor cell ID is set, it is tried whether the neighbor cell ID can be received from the macro cell MC2 of the neighbor cell ID included in the femto cell search trigger information, and the neighbor cell ID can be received (in step 4j). Yes), it turns out that it is more likely to be in femtocell FC2 again.

  On the other hand, the mobile phone MS0 has a relative distance from the base station device BS1 that is comparable to the mobile phone MS2, so the distance between the base station device BS1 and the access point AP1 is mainly the base station device BS1. It has been confirmed that it is on a concentric circle with a radius of, and there is a high possibility that it will be in the femtocell FC2 again.

  However, since the neighbor cell ID is set, it is tried whether the neighbor cell ID can be received from the macro cell MC2 of the neighbor cell ID included in the femto cell search trigger information, but the neighbor cell ID cannot be received (in step 4j). No), so it turns out that the possibility of being in femtocell FC2 is low.

  In step 4k, the femtocell search control unit 104 monitors the state of data communication and determines whether data communication is started. If data communication has been started, the process proceeds to step 4m. On the other hand, if data communication has not been started, the process proceeds to step 4l. Whether or not data communication is started is determined by whether or not communication application software such as a Web browser or mailware is being executed (whether or not a user has requested execution). Also good.

  In step 41, the femtocell search control unit 104 determines whether or not a preset time has elapsed since the start of data communication monitoring in step 4k. Here, when the preset time has elapsed, the process proceeds to step 4c for reconfirmation, and when it has not elapsed, the process proceeds to step 4k to continue monitoring.

  In step 4m, the femtocell search control unit 104 controls each unit of the radio communication unit 10 based on the femtocell ID, the center frequency information, and the synchronization timing information included in the femtocell search trigger information read in step 4a. A search for a cell (femto HGW) is started, a reference signal transmitted from the access point AP is received, and the process proceeds to step 4n.

  In step 4n, when the femtocell search control unit 104 can receive the reference signal from the access point AP corresponding to the femtocell ID, the femtocell search control unit 104 proceeds to step 4p, but cannot receive the reference signal from the access point AP. If so, the process proceeds to step 4o.

  In step 4o, the femtocell search control unit 104 determines whether or not a preset time has elapsed since the start of the femtocell search in step 4m. Here, if the preset time has elapsed, the process proceeds to step 4a. If not, the process proceeds to step 4n and the search is continued.

  In step 4p, the femtocell search control unit 104 instructs the reselection / handover control unit 106 to reselect to the access point AP that transmits the reference signal received in step 4n, and proceeds to step 4q. The reselection / handover control unit 106 that has received the instruction controls each unit of the wireless communication unit 10 to establish a communication link with the access point AP according to a predetermined communication protocol.

  In step 4q, the femto cell search control unit 104 establishes the communication link in step 4p using the femto cell search trigger information read in step 4a among the femto cell search trigger information stored in the femto cell search trigger information storage unit 51. The femtocell ID, center frequency information, and synchronization timing information obtained at this time are updated, and the process proceeds to step 4r.

  In step 4r, the femtocell search control unit 104 monitors the state of the wireless communication unit 10, received data, and the like, and determines whether or not communication with the access point AP that has established the communication link in step 4p is no longer possible. If it is determined that communication can no longer be performed, the process proceeds to step 4s. On the other hand, if communication is possible, the process proceeds to step 4r and monitoring is continued.

  In step 4 s, the femtocell search control unit 104 controls each unit of the radio communication unit 10 to measure the received power level of the macro cell that has acquired the cell ID in step 4 a and to the reselection / handover control unit 106. The base station apparatus BS is instructed to reselect, and the process proceeds to step 4t. The reselection / handover control unit 106 that has received the instruction controls each unit of the radio communication unit 10 to search for a base station apparatus BS with the best communication environment based on the measurement result of the RSSI measurement unit 15 and the like. If detected, this fact is notified to the femtocell search control unit 104.

  In step 4t, the femtocell search control unit 104 instructs the reselection / handover control unit 106 to reselect the base station apparatus BS detected in step 4s, and proceeds to step 4u. The reselection / handover control unit 106 that has received the instruction controls each unit of the radio communication unit 10 to establish a communication link with the base station apparatus BS according to a predetermined communication protocol. Notify the femtocell search control unit 104.

  In step 4u, the femtocell search control unit 104 updates the RSSI information in the femtocell search trigger information read in step 4a with the received power level measured in step 4s, and proceeds to step 4a. In the macro cell search in step 4s, when another macro cell is detected in addition to the macro cell whose cell ID was acquired in step 4a, the ID of the other macro cell is read as the adjacent cell ID and read in step 4a. In addition to femtocell search trigger information.

  As described above, in the mobile phone configured as described above, the macro cell that is waiting for an incoming call is associated with the femto cell, and the received power level of the macro cell is the same as that of the previous femto cell communication. When the received power level of the macro cell is similar, the femto cell search is started.

  Therefore, according to the mobile phone configured as described above, the femto cell search is started only when it is determined that there is a high possibility of being in the femto cell cover area based on the received power level of the macro cell. A femtocell can be detected.

  In the mobile phone configured as described above, information on femtocells used in a situation where signals from a plurality of macro cells can be received is stored, and signals from a plurality of macro cells can be received based on this information. In the case of a failure, the femto cell search is started.

  Therefore, according to the mobile phone configured as described above, the femto cell search is started only when there is a high possibility of being within the coverage area of the femto cell based on the reception status of a plurality of macro cells. Can be detected.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  As an example, for example, in the above-described embodiment, when a radio signal can be received from a plurality of preset base station apparatuses, femtocell search is started. When the received power level of each base station apparatus changes across the threshold set for each base station apparatus (or when the received power level of each base station apparatus changes within a predetermined range based on the threshold) In addition, the femto cell search may be started. Note that the threshold value to be set is determined based on the received power level of the radio signal received from each base station apparatus when performing communication through the femtocell.

  According to this, in a situation where femtocells overlap multiple macrocells, the principle of triangulation based on the received power level of each macrocell can determine the possibility of being within the coverage area of the femtocell, and only when the possibility is high By starting the femtocell search, femtocells can be detected efficiently.

In the above embodiment, the frequency and synchronization timing used in the macro cell and the femto cell are not described in detail, but the frequency and synchronization timing used between the macro cell and the femto cell may be different.
In addition, it goes without saying that the present invention can be similarly implemented even if various modifications are made without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Wireless communication part, 11 ... Wireless part, 12 ... Demodulation part, 13 ... Rate conversion part, 14 ... Decoding part, 15 ... RSSI measurement part, 20 ... Display part, 30 ... Call part, 31 ... Speaker, 32 ... Microphone , 40 ... operation section, 50 ... storage section, 51 ... femtocell search trigger information storage section, 100 ... main control section, 101 ... error correction processing section, 102 ... received data processing section, 103 ... cell ID detection section, 104 ... Femtocell search control unit, 105 ... Data communication detection unit, 106 ... Reselection / handover control unit, AP, AP1 to AP2 ... Access point, BS, BS1 to BS2 ... Base station apparatus, FC1 to FC2 ... Femtocell, MC1 ... Macro cell, MC2 ... macro cell, MNW ... mobile communication network, MS0 ... mobile phone, MS1 ... mobile phone, MS2 ... mobile phone, PNW ... public network, TD1-TDn ... femtocell search trigger information.

Claims (9)

In a mobile radio terminal capable of radio communication with a macro base station and a femto base station that forms a femto cell overlapping a macro cell formed by the macro base station,
Storage means for storing both of the identification information of the macro base station and the femto base station in which cells overlap each other,
Detecting means for detecting the received power level of the received signal;
When the reception power level of the radio signal transmitted from the macro base station in which the storage unit stores the identification information satisfies a preset condition, the femto base station in which the identification information is associated with the macro base station is searched. A mobile radio terminal apparatus comprising: search means for performing   The search means is provided to the macro base station when the received power level of a radio signal transmitted from the macro base station in which the storage means stores identification information satisfies a preset condition and performs data communication. The mobile radio terminal apparatus according to claim 1, wherein the mobile radio terminal apparatus searches for a femto base station associated with identification information. The storage means includes both identification information of a macro base station and a femto base station in which cells overlap each other, and identification of adjacent macro base stations other than the macro base station that can receive a radio signal when communicating with the femto base station. Store information in association,
The search means can receive a radio signal from the adjacent macro base station when the reception power level of the radio signal transmitted from the macro base station in which the storage means stores the identification information satisfies a preset condition. In this case, the mobile radio terminal apparatus according to claim 1, wherein a femto base station in which identification information is associated with the macro base station is searched.   The searching means may store the identification information in the macro base station when the reception power level of the radio signal transmitted from the macro base station in which the storage means stores the identification information changes exceeding a preset threshold level. The mobile radio terminal apparatus according to any one of claims 1 to 3, wherein the associated femto base station is searched.   The search means identifies the macro base station when the received power level of a radio signal transmitted from the macro base station in which the storage means stores identification information changes within a range based on a preset threshold level. The mobile radio terminal apparatus according to any one of claims 1 to 3, wherein a femto base station associated with information is searched.   The threshold level is a value based on a received power level detected from a received signal from the macro cell by the detecting means when communicating with the femto base station in the past. The mobile radio terminal device described in 1. In a mobile radio terminal capable of radio communication with a macro base station and a femto base station that forms a femto cell overlapping a macro cell formed by the macro base station,
A storage unit that associates and stores identification information of a plurality of macro base stations that form a macro cell overlapping the femto cell;
A mobile radio terminal apparatus comprising: search means for searching for the femto base station when radio signals from a plurality of macro base stations associated in the storage means can be received. Furthermore, a detection means for detecting the received power level of the received signal is provided,
The storage means stores a reception level of a radio signal received from each of a plurality of macro base stations forming a macro cell overlapping the femto cell in association with the identification information when communicating with the femto base station,
The search means searches for the femto base station when radio signals satisfying conditions based on reception levels stored in the storage means can be received from a plurality of macro base stations associated in the storage means, respectively. The mobile radio terminal apparatus according to claim 7.   The searching means searches for the femto base station when it can receive radio signals satisfying the conditions from a plurality of macro base stations associated in the storage means and performs data communication. The mobile radio terminal apparatus according to claim 7.

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