JP2007027877A - Communication terminal and handover method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to realize low power consumption and improve the communication quality, without executing wasteful control. <P>SOLUTION: A target signal detection circuit 113 for receiving a particular wireless signal, other than a wireless signal used for communication detects the particular wireless signal, set in advance, by a receiver 100 on the basis of a signal from an RF circuit 112 and informs a target signal monitor circuit 114 about the detected signal. The target signal monitor circuit 114 monitors the particular wireless signal, set in advance, by the receiver 100, on the basis of a result of the detection by the target signal detection circuit 113 and the signal from the RF circuit 112. A cell search frequency discrimination circuit 115 executes control of significantly lowering the cell search frequency or the frequency of reception level measurement or not executing the cell searching or the measurement of the reception level at all, when the circuit 115 is able to receive the particular signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication terminal apparatus and a handover method in a mobile communication system, and more particularly to improvement of cell search, cell monitoring, and handover control.

  In the cellular mobile communication system, a wide service area is configured by a plurality of cells, and a mobile device moving within the service area continues communication while appropriately selecting a cell optimal for communication as it moves. Therefore, when it is determined periodically or necessary, so-called cell search and reception status of known cells are monitored, and handover control is performed to stably continue communication based on the information.

  The frequency of performing the cell search and the known cell reception state monitoring is generally variably controlled according to the reception state of the communicating cell, the moving speed of the own device, and the like.

  FIG. 7 is a diagram illustrating an example of a conventional algorithm for determining a neighboring cell search frequency. In step S1, for example, if the reception level of the cell being communicated is below a certain threshold and no other cell with good reception status has been detected, there is a high possibility that communication will be interrupted. An attempt is made to detect an unknown cell with a good reception state, and the frequency of cell search is increased. In addition, when the moving speed is fast, it is expected that cells with good reception status will be changed in a short time, and means to realize a terminal that is unlikely to cause communication interruption by finding a cell that becomes effective in the future at an early stage Therefore, the frequency of cell search is increased.

  On the other hand, if multiple cells with good reception are detected and the moving speed is not fast, even if the reception state of one cell deteriorates, there is a possibility that there is an alternative good reception cell. Therefore, the frequency of cell search is lowered to suppress current consumption.

  As in a method such as CDMA (Code Division Multiple Access), the communication CH used for communication may be different from the CH for measuring the reception level for each cell. Even if it is determined that the quality is poor, the frequency of cell search is increased.

  Whether or not to perform handover control is generally determined by comparing the reception level measurement results of the cell in communication with other cells with a certain hysteresis, and when the reception level is higher than the cell in communication. , Perform handover control.

  FIG. 8 is a block diagram showing functions from the antenna to the demodulation of the conventional receiving apparatus.

  In FIG. 8, the receiving device 10 includes an antenna 11, an RF circuit 12, a cell search circuit 13, a reception level measurement circuit 14, a demodulation circuit 15, a reception state monitoring circuit 16, and a cell search frequency determination circuit 17. .

  The cell search circuit 13 searches for unknown cells around its own device in accordance with the frequency designation from the cell search frequency determination circuit 17.

  The reception level measurement circuit 14 measures the reception state of a known cell in accordance with an instruction from a control unit (not shown), and outputs it to the cell search frequency determination circuit 17.

  The demodulation circuit 15 performs demodulation processing in accordance with an instruction from a control unit (not shown), and outputs the reception quality of the communication channel to the reception state monitoring circuit 16.

  The reception state monitoring circuit 16 monitors the reception quality of the communication channel and outputs necessary information to the cell search frequency determination circuit 17.

  The cell search frequency determination circuit 17 designates the frequency for the cell search circuit 13 according to the algorithm described in FIG.

  In the above configuration, the receiving apparatus 10 periodically searches for unknown cells in the surroundings during communication and in standby, and similarly periodically monitors the reception status of the known neighboring cells to obtain information. Stable communication is performed by performing control based on information.

  Realizing stable communication while minimizing the periodic cell search and cell monitoring operations is an important factor in reducing power consumption.

  Patent Document 1 discloses a mobile communication terminal that detects a change in reception level and shortens activation of cell search when a sudden change in reception environment occurs.

Patent Documents 2 and 3 disclose an apparatus and a handover method for searching for line connection history information, predicting a cell that will move next, and executing a handover decision. In any case, unnecessary cell search, cell reception level measurement, and handover control are determined, and power consumption is reduced by not performing the determination.
Japanese Patent Laid-Open No. 10-126830 JP 2004-289226 A JP 2001-169323 A

  However, in such a conventional mobile communication terminal, it is difficult to set an appropriate cell search and cell reception level measurement frequency in all reception environments, and communication disconnection is possible in terms of communication quality in mobile communication. However, even if it is known that there is a case where it is useless at the expense of a reduction in current consumption in order to reduce the performance, the fact is that the cell search and the cell reception level measurement are performed at a certain frequency.

  FIG. 9 is a diagram for explaining the determination of the neighboring cell search frequency, and shows an example in which the battery consumption of the mobile terminal of a specific user is remarkably accelerated as a result of the control. In FIG. 9, the base station 20 configures a service area with a cell Cell # A. It is assumed that the mobile terminal 30 moving in the service area stays in a range where the cell Cell # A can be received somehow for a long time. The place where the user stays for a long time is, for example, a residence or a stay at a boundary point that can barely be received from the cell Cell # A. In addition, there is only one base station in the vicinity, and there is only one neighboring cell.

  The mobile terminal 30 periodically communicates with a cell Cell # A that can be received only at regular intervals during standby, even if it is not communicating. However, since the reception level of the cell Cell # A that can be communicated is low, control is performed to search for a cell with better reception quality in the vicinity. In this case, since there are no other cells around the place where the user stays for a long time, there is a problem in that the current search is repeated and the current is consumed wastefully unless a control that does not give up searching for the neighboring cell is employed. Similarly, there is the same problem regarding the frequency of cell reception level measurement.

  As for handover control, in a special environment, there is a case where a result without interruption of communication is obtained when the handover control is not performed.

  FIG. 10 is a diagram illustrating a case where communication is not interrupted when handover control is not performed. In FIG. 10, the reception from one cell (cell Cell # A) is almost hidden behind the building C with respect to the mobile terminal 40 moving in the handover state of the two cells Cell # A and Cell # B in the CDMA system. When it becomes invisible, since communication with 1 cell (cell Cell # B) that seems to be in good communication can be secured in normal handover control, cell Cell # A that has disappeared is deleted. However, immediately after that, the mobile terminal 40 moves from the shadow of the building C, and the cell Cell # A that has disappeared can be seen. At the same time, the cell Cell # B that has been received well up to now is hidden in the shadow of the building D. think of. In that case, the cell Cell # A once deleted is measured again, knowing that the reception level has increased, and communication does not return until the cell Cell # A is added. In this example, there is a high possibility that communication can be performed intermittently unless handover control is performed to delete the cell Cell # A, but the mobile terminal 40 has no means of knowing it, so there is a problem that communication is interrupted. there were.

  On the other hand, there is a problem that there is a special region where communication is interrupted if handover control is not performed immediately, although conditions are not satisfied for performing handover control.

  In addition, if a microcell base station is installed on a vehicle such as a train or ship, there is almost no need to perform a neighbor cell search or handover while on the vehicle, and wasteful processing is performed. There was a problem.

  The present invention has been made in view of the above points, and is a communication terminal capable of realizing low power consumption and improving communication quality without performing useless control such as cell search or cell reception level measurement. An object is to provide an apparatus and a handover method.

  The communication terminal device of the present invention includes a cell search means for searching for a handover destination base station, a reception means for receiving a specific radio signal different from a radio signal used for communication with the base station, and the received specific signal Detecting means for detecting cell search control information for controlling a cell search state from a radio signal; and, when the cell search control information is detected, reducing or stopping the frequency of searching for neighboring cells executed by the cell search means And a control means for performing the control.

  Further, the communication terminal apparatus of the present invention includes a cell search means for searching for a handover destination base station, a detection means for detecting a specific scrambling code from a radio signal used for communication with the base station, And a control means for controlling the cell search means based on a scrambling code.

  The handover method of the present invention includes a step of searching for a handover destination base station, a step of receiving a specific radio signal different from a radio signal used for communication with the base station, and a cell from the received specific radio signal. Detecting search control information; and, when the cell search control information is detected, performing a control to lower or stop a frequency of searching for neighboring cells or a frequency of monitoring a cell reception state.

  The handover method of the present invention includes a step of searching for a handover destination base station, a step of detecting a specific scrambling code transmitted from a pseudo cell installed in a specific area, and a specific method transmitted from the pseudo cell. Performing handover control including cell deletion restriction based on the scrambling code.

  ADVANTAGE OF THE INVENTION According to this invention, the useless operation | movement of the communication terminal device in a specific area can be suppressed, and low power consumption can be aimed at.

  In addition, it is possible to change the handover control that causes a communication interruption in a specific area and perform stable communication.

  As a result, low power consumption can be realized and communication quality can be improved.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing functions from the antenna to the demodulation of the receiving apparatus of the communication terminal apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, a receiving device 100 is a communication terminal device such as a mobile phone / PHS (Personal Handy-Phone System) or a personal digital assistant (hereinafter referred to as PDA (Personal Digital Assistants)) that performs wireless communication, and is used for communication. A specific radio signal different from the radio signal to be received can be received. The specific radio signal is specifically a radio signal used in each service of Bluetooth (registered trademark), UWB (Ultra Wideband), or wireless LAN (Local Area Network) using a network other than the carrier. In FIG. 1, a mobile phone is taken as an example of the communication terminal device.

  The receiving apparatus 100 includes an antenna 101, an RF circuit 102, a cell search circuit 103, a reception level measurement circuit 104, a demodulation circuit 105, a reception state monitoring circuit 106, a specific radio signal reception antenna 111, an RF circuit 112, and a target signal detection circuit 113. The target signal monitoring circuit 114 and the cell search frequency determination circuit 115 are provided.

  The cell search circuit 103 searches for unknown cells around its own device in accordance with the frequency designation from the cell search frequency determination circuit 115.

  The reception level measurement circuit 104 measures the reception state of a known cell in accordance with an instruction from a control unit (not shown), and outputs it to the cell search frequency determination circuit 115.

  Demodulation circuit 105 performs demodulation processing according to an instruction from a control unit (not shown), and outputs the reception quality of the communication channel to reception state monitoring circuit 106.

  The reception state monitoring circuit 106 monitors the reception quality of the communication channel and outputs necessary information to the cell search frequency determination circuit 115.

  The cell search frequency determination circuit 115 performs frequency designation for the cell search circuit 103 by the algorithm described in FIG.

  The antenna 101, RF circuit 102, cell search circuit 103, reception level measurement circuit 104, demodulation circuit 105, and reception state monitoring circuit 106 are the antenna 11, RF circuit 12, cell search circuit 13, and reception level measurement of FIG. The circuit 14, the demodulation circuit 15, and the reception state monitoring circuit 16 have the same functions.

  The specific radio signal receiving antenna 111 receives a specific radio signal different from the radio signal used for communication, for example, a specific radio wave by Bluetooth (registered trademark).

  The RF circuit 112 is an RF circuit for receiving a specific radio signal set in advance by the receiving apparatus 100, processes a signal from the specific radio signal receiving antenna 111, and processes it as a target signal detection circuit 113. Output to the target signal monitoring circuit 114. The RF circuit 112 is different from the RF circuit 102 in use frequency band, modulation method, and the like, and therefore needs to be a separate wireless control unit.

  The target signal detection circuit 113 detects a specific radio signal set in advance by the receiving apparatus 100 based on the signal from the RF circuit 112 and notifies the target signal monitoring circuit 114 of the detection signal.

  The target signal monitoring circuit 114 monitors a specific wireless signal set in advance in the receiving apparatus 100 based on the detection result of the target signal detection circuit 113 and the signal from the RF circuit 112. Specifically, the reception level is measured and the reception is determined, and the determination result is notified to the cell search frequency determination circuit 115.

  The cell search frequency determination circuit 115 determines the cell search frequency according to an algorithm described later with reference to FIG.

  Hereinafter, the operation of the communication terminal apparatus configured as described above will be described.

  FIG. 2 is a flowchart showing an algorithm for determining the neighboring cell search frequency. The same elements as those in the algorithm shown in FIG.

  First, in step S11, it is determined whether or not a specific signal different from the radio signal used for communication can be received. If the specific signal can be received, the cell search frequency determination circuit 115 is the target in step S12. Based on the presence / absence of reception of a specific signal from the signal monitoring circuit 114, the cell search frequency is greatly reduced or a setting for not performing any cell search is output to the cell search circuit 103. On the other hand, if a specific signal different from the radio signal used for communication is not received in step S11, the conventional cell search frequency is determined in step S1 and the set cell search frequency is output to the cell search circuit 103. Describing step S1 again, if the reception level of the cell being communicated is below a certain threshold and no other cell in a good reception state has been detected, there is a high possibility that communication will be interrupted. It may try to detect an unknown cell with a good reception state and increase the frequency of cell search. In addition, when the moving speed is fast, it is expected that cells with good reception status will be changed in a short time, and means to realize a terminal that is unlikely to cause communication interruption by finding a cell that becomes effective in the future at an early stage Therefore, the frequency of cell search is increased. If multiple cells with good reception are detected and the moving speed is not fast, even if the reception state of one cell deteriorates, there is a possibility that an alternative good reception cell exists. Reduce the frequency of search to reduce current consumption.

  That is, this algorithm is the same as the conventional algorithm when a specific signal cannot be received, and when the specific signal can be received, the cell search frequency is set to be significantly reduced or not set at all.

  FIG. 3 is a diagram for explaining the effect of the communication terminal device according to the present embodiment, and corresponds to FIG.

  In FIG. 3, the user carrying the receiving apparatus 100 stays in a residence 130 within a range where the transmission wave 120 from the cell Cell # A of a base station (not shown) can be received. In the residence 130, a transmission device 140 adjusted so that a specific radio signal can be transmitted is installed only in the residence. The transmission device 140 is a transmission base station adopting a wireless LAN and Bluetooth (registered trademark) for transmitting a specific radio signal in a narrow area, and has an area 150 where the specific radio signal can be received.

  The receiving apparatus 100 is in a state where it can receive and recognize the specific radio signal. When the specific radio signal can be received, the receiving apparatus 100 performs a setting for greatly reducing the frequency of cell search or not performing any cell search.

  As a result, as long as the receiving apparatus 100 stays in the area 150, the receiving apparatus 100 does not perform a useless cell search operation, and battery consumption can be suppressed.

  Also, the reception level measurement frequency is controlled in the same way as in cell search. By applying the same configuration and algorithm as in cell search frequency determination, useless reception level measurement can be reduced, and low consumption is achieved. Electricity becomes possible.

  The above is the effect of reducing the power consumption of the cell search operation and improving the accuracy of reception level measurement, but it is also possible to use detection / supervision of a specific radio signal other than the cell search operation and reception level measurement. For example, when it is desired to restrict transmission and communication itself in a public place such as a hospital or a library, a function for restricting transmission and communication is provided while the mobile terminal can receive a common specific signal. This function is preferably provided in all mobile terminals. Thereby, it becomes possible to restrict | send transmission in public places, such as a hospital and a library.

  It is also possible to adopt a configuration in which the user sets in advance a specific radio signal and the control content when a specific radio signal is received. For example, in this embodiment, the cell search frequency is changed when a specific signal different from the radio signal used for communication can be received, but how to perform handover when a specific signal is received. Whether to perform control can be arbitrarily set.

  Here, by using a wireless LAN or Bluetooth as a specific wireless signal, it can be realized using existing equipment. In recent years, mobile terminals equipped with wireless LAN functions have emerged due to miniaturization of chips as well as Bluetooth, and in this embodiment, the cost increases by diverting these wireless LAN functions that can only be received within a local range. Can be easily implemented without incurring

  As described above, as a human interface for registering a specific signal, there is provided a means for searching, displaying, selecting, and setting all currently received signals that can be registered as a specific wireless signal by the receiving apparatus 100. Therefore, convenience for the user is improved.

  In addition, with regard to the challenges of installing microcell base stations in vehicles, it is possible to eliminate unnecessary cell searches and handovers by installing devices that transmit specific radio signals in the vehicles as well. , Low power consumption can be achieved.

(Embodiment 2)
Embodiment 2 is a W-CDMA (Wideband Code Division Multiple Access) method of a base station asynchronous CDMA communication method, and a specific radio signal includes a scrambling code synchronization CH (PSCH + SSCH) and a common pilot CH (CPiCH). ) Is set as an example. In this case, it is assumed that the scrambling code is not used in a normal cell.

  FIG. 4 is a block diagram showing functions from the antenna to the demodulation of the receiving apparatus of the communication terminal apparatus according to Embodiment 2 of the present invention. In the description of the present embodiment, the same constituent elements as those in FIG.

  In FIG. 4, the receiving apparatus 200 includes an antenna 101, an RF circuit 102, a cell search circuit 103, a reception level measurement circuit 104, a demodulation circuit 105, a reception state monitoring circuit 106, and a cell search frequency determination circuit 201. .

  A W-CDMA mobile terminal periodically performs cell search and measurement of a known cell reception level, and the operation detects and monitors a (pseudo) cell of a scrambling code set as a specific signal in the same manner. It will be possible.

  1 is different from the receiving apparatus 100 in FIG. 1 in that a block for detecting and monitoring a specific radio signal is not separately provided. 1 is the RF circuit 102 of FIG. 4, the target signal detection circuit 113 of FIG. 1 is the cell search circuit 103 of FIG. 4, and the target signal monitoring circuit 114 of FIG. 1 is the reception level measurement of FIG. Circuits 104 can be substituted for each.

  Therefore, the same effect as in the first embodiment can be obtained without increasing the number of circuits for detecting and monitoring a specific radio signal. In addition to the effects described above, this embodiment can be applied to a communication terminal device whose radio communication system is the CDMA system, so that handover control during movement can be effectively performed as described below.

  FIG. 5 is a diagram for explaining the effect of the communication terminal device according to the present embodiment, and corresponds to FIG. FIG. 6 is a table showing an example of the special scrambling code (SCNo).

  As shown in the table of FIG. 6, the scrambling codes 0x0010, 0x0020, 0x0030, 0x0040, and 0x0050 are designated as special scrambling codes No, and the control contents are shown in the table. Special SC Nos = 0x0010, 0x0020, 0x0030, 0x0040, and 0x0050 are not used in a normal cell, and special control contents for changing a condition for handover control when a cell of each code is received are shown.

  For example, in special SCNo = 0x0010, cell delete is limited as an example of changing the conditions for handover control. This is to change the control so that even if there is a cell to be deleted if the reception level is low in the handover control and there is a cell to be deleted, it is determined that the cell signal can be received. Alternatively, in the change of the handover control condition indicated by special SCNo = 0x0050, the cell is easily added. As described above, in the control contents using the special SCNo, the handover control conditions are set / changed as indicated by the special SCNo = 0x0010, 0x0050 in addition to the cell search operation setting indicated by the special SCNo = 0x0020, 0x0030, 0x0040. The control content of the special SCNo is an example and is not limited. It is also possible to adopt a configuration in which the user selects and sets the control content of the special SCNo. When the user sets / changes the cell search operation setting and the handover control condition, mobile communication suitable for the user's intention becomes possible. For example, handover control such as giving priority to avoiding communication interruption over low power consumption in a special environment as shown in FIG. 5 becomes possible. In addition, the fact that each user can set conditions individually can realize finely detailed handover control that can be set only by each user.

  The above is an example, and it is possible to change and set the control content for each of a plurality of specific radio signals.

  In this way, a specific scrambling code is set, and a pseudo cell with a scrambling code of 0x0010 is installed in the corresponding area. At the time of installation, taking into account the maximum speed of the receiving device 200 (hereinafter referred to as “mobile terminal” in order to focus on movement) and the maximum interval of the peripheral cell search cycle of the mobile terminal, Receivable area) is determined.

  The pseudo cell transmits only the CPiCH with the scrambling code 0x0010 and the PSCH and SSCH in accordance with the timing.

  Hereinafter, an operation when the mobile terminal (receiving apparatus 200) approaches and passes through the corresponding area will be described.

  First, when the mobile terminal has not yet received the radio signal from the pseudo cell, the scrambling code is simultaneously with two cells of cell Cell # A and cell Cell # B having a normal SCNo other than the special SCNo. Assume communication (handover). In that case, the mobile terminal receives RAKE signals from both cells and is in a good quality reception state.

  Next, when the mobile terminal enters an area where the radio signal from the pseudo cell can be received, a periodic cell search is performed thereafter, and the pseudo cell can be detected. Once a pseudo cell is detected, then periodic cell monitoring (reception level measurement) is also performed on the SCNo of the pseudo cell. While it is determined that reception is possible, handover control is performed. Restrict cell deletion.

  When the mobile terminal enters the shadow of the building C and cannot receive from the cell Cell # A, the periodic cell monitoring shows that the reception level from the cell Cell # A is low and reception is not possible. After that, generally, protection for a certain amount of time is applied, and if the reception level is low even after that time, cell Cell # A is controlled to be deleted, but pseudo cell 0x0010 that restricts cell deletion can be received. Therefore, cell Cell # A is not deleted.

  Further, when the mobile terminal removes the shadow of the building C and receives from the cell Cell # A, the mobile terminal enters the shadow of the building D and enters the area where the reception from the cell Cell # B cannot be received. Since #A and cell Cell # B are in the handover state, if a path search that is regularly performed at a shorter interval than cell monitoring is performed, reception from cell Cell # A can be performed promptly.

In general, the cell monitoring interval of a cell in communication and the cell monitoring interval of other known cells are
(Cell monitoring interval of communicating cell) <(Cell monitoring interval of other known cells)
The difference is considerably large from the viewpoint of low power consumption and processing performance constraints.
It is said that (cell monitoring interval of a cell during communication) = 40 ms and (cell monitoring interval of other known cells) = 200 ms are desirable.

  After that, the shadow of the building D is removed, and the reception from the cell Cell # B is also improved. Finally, the control returns to the normal control by removing from the reception area of the pseudo cell.

  In this way, it is possible to avoid the communication disconnection that has been a problem in FIG.

  Conversely, if the cell Cell # A in FIG. 5 is far from the mobile terminal and the cell Cell # A has not reached the reception level to be handed over before entering the shadow of the building C, the building If the cell Cell # B cannot be received in the shadow of the building D by being added as a handover target before the shadow of the cell C, the cell Cell # A is in the building C in the environment where communication is not interrupted. If a pseudo cell with a special SCNo of 0x0050 is installed in the area immediately before entering the shadow of, it is easy to add a handover cell while the pseudo cell can be received. There is a high possibility that the cell Cell # A has been added as a handover target cell before entering, and communication disconnection can be avoided.

  As described above, according to the present embodiment, low current consumption can be achieved as in the first embodiment by not performing useless operations such as cell search or cell reception level measurement. Further, since it is not necessary to detect / monitor a specific radio signal different from the radio signal used for communication, a small configuration is possible. For the same reason, there is no increase in the number of parts, and there is an effect that it is easy to implement at low cost.

  Further, in the present embodiment, a base station asynchronous CDMA communication method is used, and a pseudo cell that transmits only a synchronous CH and a common pilot CH of a specific scrambling code is specified to change the control of a part of a mobile terminal. In such a special environment as shown in FIG. 5 (for example, cell control), the mobile terminal changes the control while receiving the signal. It is possible to avoid communication interruptions by changing the deletion limit.

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this.

  Note that the communication terminal apparatus and the handover method of the present invention are not limited to the above-described embodiments, and it is needless to say that various changes can be made without departing from the scope of the present invention. For example, a mobile terminal such as a mobile phone is used as the communication terminal device, but the present invention is not limited to a mobile phone and can be applied to a device having a wireless communication function or a combination thereof. In addition, as a device capable of wireless communication, a device integrated with an information device function represented by a personal computer may be used, and it can be applied to all systems. Further, any communication method may be used.

  In addition, the types of processing units and the like and the type / format of the setting information constituting the communication terminal device and the mobile communication system are not limited to the above-described embodiments.

  Further, although the names of the communication terminal apparatus and the handover method are used in the present embodiment, this is for convenience of explanation, and may be a mobile communication terminal, a handover control method apparatus, or the like.

  The handover method described above is also realized by a program for causing this transmission method to function. This program is stored in a computer-readable recording medium.

  As described above, the communication terminal device and the handover method according to the present invention are useful in a mobile communication system that can eliminate wasteful processing in a special environment and improve communication quality. It is.

The block diagram which shows the function from the antenna of the receiver of the communication terminal device which concerns on Embodiment 1 of this invention to a demodulation. Flow chart showing an algorithm for determining the neighboring cell search frequency of the communication terminal apparatus according to the first embodiment. The figure explaining the effect of the communication terminal device which concerns on this Embodiment 1. The block diagram which shows the function from the antenna of the receiver of the communication terminal device which concerns on Embodiment 2 of this invention to a demodulation. The figure explaining the effect of the communication terminal device which concerns on the said Embodiment 2. The figure which shows an example of the special scrambling code (SCNo) of the communication terminal device which concerns on the said Embodiment 2 as a table | surface. The figure which shows an example of the algorithm which determines the conventional periphery cell search frequency Block diagram showing functions from antenna to demodulation of conventional receiver The figure explaining the conventional periphery cell search frequency determination The figure explaining the case where the direction which does not perform the conventional handover control does not interrupt communication

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,200 Receiver 101 Antenna 102,112 RF circuit 103 Cell search circuit 104 Reception level measurement circuit 105 Demodulation circuit 106 Reception state monitoring circuit 111 Specific radio signal receiving antenna 113 Target signal detection circuit 114 Target signal monitoring circuit 115, 201 cell Search frequency judgment circuit

Claims (8)

Cell search means for searching for a handover destination base station;
Receiving means for receiving a specific radio signal different from a radio signal used for communication with the base station;
Detecting means for detecting cell search control information for controlling a state of cell search from the received specific radio signal;
A communication terminal device comprising: control means for controlling to reduce or stop the frequency of searching for neighboring cells executed by the cell search means when the cell search control information is detected. The cell search means monitors a cell reception state at a predetermined frequency,
The communication terminal apparatus according to claim 1, wherein when the cell search control information is detected, the control means performs control to reduce or stop a frequency of monitoring a reception state of a cell executed by the cell search means.   The communication terminal apparatus according to claim 1 or 2, further comprising setting means for setting the predetermined cell search control information in the specific radio signal. Cell search means for searching for a handover destination base station;
Detecting means for detecting a specific scrambling code from a radio signal used for communication with the base station;
And a control means for controlling the cell search means based on the specific scrambling code. A pseudo cell for transmitting the specific scrambling code is installed in a specific area,
The communication terminal apparatus according to claim 4, wherein the control means performs handover control including restriction on cell deletion based on a specific scrambling code transmitted from the pseudo cell.   The communication terminal apparatus according to claim 4 or 5, further comprising setting means for setting cell search and handover control contents given by the specific scrambling code. Searching for a handover destination base station;
Receiving a specific radio signal different from a radio signal used for communication with the base station;
Detecting cell search control information from the received specific radio signal;
A step of performing control to lower or stop the frequency of searching for neighboring cells or the frequency of monitoring the reception status of cells when the cell search control information is detected. Searching for a handover destination base station;
Detecting a specific scrambling code transmitted from a pseudo cell installed in a specific area;
Performing handover control including restriction on cell deletion based on a specific scrambling code transmitted from the pseudo cell.

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