JP4632799B2 - Mobile communication terminal and handover system using the same - Google Patents

Description

  The present invention relates to a portable communication terminal and a handover system using the same, and more particularly to a portable communication terminal having a radio wave relay function and a handover system using the portable communication terminal.

  When a mobile communication terminal such as a mobile phone moves while communicating with a partner terminal, it prevents a call interruption due to a deterioration in reception state when moving from the zone of the currently communicating base station to the zone of an adjacent base station. Therefore, handover is performed to switch to communication with a base station in a zone with good reception conditions.

  At this time, the mobile communication terminal receives, for example, a GPS signal transmitted from an artificial satellite (GPS satellite) constituting a global positioning system (GPS), and based on the received GPS signal, the current position The location information is transmitted to the base station together with the power information, and the base station is based on the received location information and power information together with the building information and weather information in the radio zone of the base station. Thus, in a handover system in which handover is performed to an optimal base station, when data is changed for optimization of handover for a part of a region, a handover failure after data change may occur. Therefore, an area where frequent disconnection due to a handover failure occurs is identified, and a memory in which specific handover data for enabling optimal handover to the mobile communication terminal in the specific area and the location information of the specific area is stored on the exchange side On the other hand, when a mobile communication terminal is provided with a GPS receiver so that the location information is always reported to the exchange via the base station, and the mobile communication terminal located in a specific area is identified in the exchange In addition, a handover system in which specific handover data is transmitted to a mobile communication terminal to forcibly execute a handover has been conventionally known (see, for example, Patent Document 1).

  In addition, in DSRC (Dedicated Short Rang Communications), which is a dedicated mobile communication protocol related to vehicles traveling on the road, the frequency of the mobile station mounted on the vehicle is equipped with a GPS receiver and is reported from the first base station. Receives information and location information, detects base station radio zone switching location based on GPS receiver data and received location information, and switches to the next base station frequency at the same time, thereby detecting handover from radio synchronization A handover system that solves the problem of communication interruption at the time of radio zone switching when performing a communication and continuously performs communication between a base station and a mobile station is also known (for example, Patent Documents). 2).

  On the other hand, portable communication terminals having a relay function are known so that high reception sensitivity can be maintained even outside the radio zone of the base station (see, for example, Patent Document 3). This patent document 3 has another relay function when a received radio signal level is lowered in order to prevent instability of communication due to movement of a mobile communication terminal or a radio relay device having a relay function. It is also disclosed that handoff control means for switching connection to a mobile communication terminal or a radio wave relay device is provided.

  In addition, in a wireless communication system composed of a base station and a plurality of mobile stations (mobile communication terminals), when the mobile station moves out of the base station wireless zone, communication that relays the base station becomes impossible. Automatic switching control from the base station relay communication mode to the direct communication mode for direct communication between mobile stations, and when the mobile station returns to the base station wireless zone, it automatically relays from the direct communication mode to the base station A wireless communication system that switches to a communication mode is also known (see, for example, Patent Document 4).

  In addition, when a plurality of wireless zones overlap each other in an ad hoc network in which a mobile communication terminal is temporarily functioned as a base station or a relay station without setting a base station or a fixed relay station, and a network is constructed. A wireless communication system that calculates the number of channels necessary to prevent interference is also conventionally known (see, for example, Patent Document 5).

Japanese Patent Laid-Open No. 10-215474 JP 2003-284115 A Japanese Patent Application Laid-Open No. 2004-166022 JP 2001-95043 A JP 2003-92779 A

  However, in the conventional handover systems described in Patent Documents 1 and 2 described above, a GPS signal from a GPS satellite cannot be received in a place where radio waves do not reach or cannot be transmitted, such as an underground shopping street. Therefore, there is a problem that handover cannot be performed. In addition, since normal handover determines which base station to exchange with reference to the strength of radio waves, communication may suddenly deteriorate.

  Furthermore, even if the inventions described in Patent Documents 3 to 5 are combined, the mobile communication terminal constituting the handover system cannot perform normal telephone communication and radio wave relay processing simultaneously, and fading changes in real time. It is not possible to obtain a configuration that effectively realizes handover by detecting a region.

  The present invention has been made in view of the above points, and has a radio wave relay function, a satellite signal reception function, and a transmission / reception function with an artificial satellite, and is in a call or data communication based on a signal from the artificial satellite. An object of the present invention is to provide a portable communication terminal capable of preventing sudden communication deterioration and a handover system using the same.

  Another object of the present invention is to provide a mobile communication terminal capable of reducing the number of installed base stations since an out-of-service area can be set as a service area, and a handover system using the same.

In order to achieve the above object, a mobile communication terminal of a first invention includes a first communication means for wirelessly communicating with a nearest base station, and a counterpart terminal connected to the base station via a network. A mobile communication terminal that performs mobile communication between them, receives a transmission signal of an arbitrary transmission destination wirelessly transmitted from another portable communication terminal, and transmits the reception signal as it is when the transmission destination of the reception signal is not its own terminal. When the transmission destination of the transmission signal wirelessly transmitted from the other mobile communication terminal received by relay transmission first is the own terminal, the second communication means for processing the reception signal without performing relay transmission ; A third communication means for communicating with the artificial satellite; an acquisition means for acquiring the position information and movement information of the own terminal and information of the base station in communication; and a communication with the acquired position information and movement information. The base station information is sent to the artificial satellite via the third communication means. Transmitted to the third sent from the communication means a satellite which is received via, among radio zones of the plurality of base stations adjacent to the fading area in the moving direction indicated by the movement information, capable of excellent communication Based on handover information to be handed over to a base station having a radio zone, the base station having a radio zone capable of performing good communication by selecting the first communication means or the second communication means during communication with the counterpart terminal Control means for performing wireless communication with the base station using another mobile communication terminal located in the wireless zone as a relay station .

  In the present invention, since the first communication means or the second communication means is selected during communication with the counterpart terminal based on the handover information received from the artificial satellite, communication is performed. Communication with the partner terminal is possible via the station.

In order to achieve the above object, the handover system of the second invention includes a plurality of base stations each having a unique radio zone, and an arbitrary base station having a radio zone in which a plurality of base stations are located, Between a mobile communication terminal that communicates wirelessly with each other and mobile communication with a partner terminal connected to any base station via a network, and an artificial satellite that communicates with the mobile communication terminal The mobile communication terminal is a first communication means for wireless communication with the nearest base station, and receives a transmission signal of an arbitrary transmission destination wirelessly transmitted from another mobile communication terminal, When the destination of the received signal is not its own terminal, the received signal is relayed to the destination as it is, and when the destination of the transmission signal transmitted wirelessly from another received mobile communication terminal is its own terminal, the relay transmission Do not Second communication means for performing processing of signals the signal, the third communication means and the own terminal position information and the movement information with the base station information acquisition means for acquiring in communication to communicate with the satellite And the acquired position information and movement information and the information of the base station in communication are transmitted to the artificial satellite via the third communication means , and the movement transmitted from the artificial satellite received via the third communication means. During communication with a partner terminal based on handover information to be handed over to a base station having a radio zone in which good communication is possible, among radio zones of a plurality of base stations adjacent to the fading area in the moving direction indicated by the information A base station having a radio zone in which good communication can be performed by selecting the first communication means or the second communication means, and another mobile communication terminal located in the radio zone as a relay station between the base station and the base station in control for performing wireless communication And a means,
The artificial satellite has a receiving means for receiving position information and movement information transmitted from the mobile communication terminal and information of the base station in communication, at least the received position information and movement information, information of the base station in communication, and movement The information processing apparatus includes: handover information generating means for generating handover information based on information on a base station in the moving direction indicated by the information; and transmission means for transmitting the generated handover information in response to the mobile communication terminal.

  In this invention, handover information is generated based on at least the position information and movement information received from the mobile communication terminal by the artificial satellite, information on the base station in communication, and information on the base station in the movement direction indicated by the movement information. Since a response is transmitted to the mobile communication terminal, a fading area in the moving direction of the mobile communication terminal is detected, and a handover for selecting communication with the optimum base station corresponding to the fading area can be performed.

In order to achieve the above object, the handover system according to the third aspect of the present invention is such that when the mobile communication terminal is not in the radio zone of the handover destination base station, the mobile communication terminal is in the radio zone of the handover destination base station. The second communication means included in the other mobile communication terminal is used to perform radio communication with the handover destination base station using the other mobile communication terminal as a relay station. In the present invention, even when moving in the fading area, the mobile communication terminal uses the relay communication function of another mobile communication terminal existing in the radio zone of the base station adjacent to the fading area to Wireless communication is possible with the station.

  According to the present invention, since a signal transmitted from another mobile communication terminal can be relayed and mobile communication can be performed with the partner terminal via the nearest base station, the other mobile communication terminal can communicate with the nearest base station. Even if it is outside the radio zone, it can communicate as if it is within the area of the nearest base station, the area can be easily expanded, and the number of base stations can be reduced.

  Further, according to the present invention, based on the position information and the movement information received by the artificial satellite from at least the mobile communication terminal, the information of the base station in communication, and the information of the base station in the movement direction indicated by the movement information, By generating handover information and sending a response to the mobile communication terminal, a handover that detects a fading area in the moving direction of the mobile communication terminal and selects an optimal base station corresponding to the fading area is performed. As a result, it is possible to perform effective handover and improve communication quality even in an environment where sudden communication disconnection due to deterioration of communication quality such as fading is likely to occur.

  Next, embodiments of the present invention will be described with reference to the drawings. 1 and FIG. 2 are system configuration diagrams showing examples of use in an embodiment of a handover system according to the present invention, and FIG. 3 is a block diagram of an embodiment of a portable communication terminal according to the present invention.

  The block diagram of FIG. 3 shows the configuration of a mobile phone as an example of a mobile communication terminal. A radio circuit 34 having a mobile communication antenna 31, a satellite signal transmitter / receiver 35 having a satellite antenna 32, and a radio wave relay antenna 33. Each of the radio relay radio circuits 36 is connected to a control circuit 37 and has three radio circuits (transceivers) 34, 35 and 36.

  The configurations of the radio circuit 34 and the radio relay radio circuit 36 are well known to those skilled in the art, and since their operations are not directly related to the present invention, detailed descriptions of their configurations and operations are omitted. The satellite signal transmitter / receiver 35 is a transmitter / receiver that wirelessly communicates with an artificial satellite (indicated by 10 in FIG. 2) used in the present invention, and the configuration thereof is the same as that of a normal transmitter / receiver. Detailed description is omitted.

  The reason why the radio circuits 34 and 36 are divided into two depending on the application is that, for example, the 2 GHz band used in the current mobile communication system is properly used in units of several MHz depending on the sector of the base station. This is because it is difficult to simultaneously use these frequency bands.

  The control circuit 37 is also connected to the operation unit 38, the display unit 39, the storage unit 40, the transmission / reception unit 41, and the information acquisition unit 42, and controls the entire mobile phone according to a program stored in advance in the storage unit 40. Control. The operation unit 38 includes a plurality of keys for inputting a telephone number, mail text, and other various information. The display unit 39 displays an image (including characters and symbols) of a signal received by the mobile communication terminal on a screen, and includes a liquid crystal display element and a drive circuit thereof. The storage unit 40 is a memory in which a program for operation control is stored in advance, and data is written and read out during the control operation of the control circuit 37.

  Further, the transmitter / receiver unit 41 performs acoustic-electrical conversion of the transmitted voice to obtain a transmitted voice signal, or generates a received voice by converting the received voice signal into electric-acoustic sound, or rings a ringtone or incoming melody. It consists of a loudspeaker. Further, the information acquisition unit 42 acquires its own position information, moving direction, and moving speed by a known means.

  First, the radio wave relay function of the mobile communication terminal according to the present invention will be described with reference to FIG. In FIG. 1, the base station 1 is in a state where it can wirelessly communicate with the mobile phones 2 and 3 having the configuration shown in FIG. On the other hand, the base station 1 is out of service area because the mobile phones 4 and 5 in the underground shopping center are not located in its own wireless zone (area), and wireless communication with the mobile phones 4 and 5 cannot be performed conventionally.

  On the other hand, the mobile phone 4 having the configuration shown in FIG. 3 in the underground shopping center is located between the mobile phones 3 and 5, relays radio waves from the mobile phone 3 to the mobile phone 5, and carries radio waves from the mobile phone 5. It is at a distance that can be relayed to the telephone 3. Therefore, in the present embodiment, when the mobile phone 5 makes a call with the partner terminal, wireless communication is performed with the base station 1 using the mobile phone 4 and the mobile phone 3 as relay stations. That is, a signal transmitted from the base station 1 to the mobile phone 5 as a transmission destination is received by the radio circuit 34 via the mobile communication antenna 31 of the mobile phone 3, and further for radio wave relay under the control of the control circuit 37. The data is transmitted to the mobile phone 4 outside the radio zone of the base station 1 via the radio circuit 36 and the radio wave relay antenna 33.

  The mobile phone 4 receives a radio signal transmitted from another mobile phone (here, the mobile phone 3) by the radio relay radio circuit 36 via the radio relay antenna 33, and the control radio circuit 37 receives the received radio signal. After the relay processing such as amplification under the control of, the radio wave relay radio circuit 36 of the mobile phone 4 transmits again to the destination mobile phone 5 via the radio wave relay antenna 33 (ie, operates as a relay station). ). The mobile phone 5 receives a radio signal transmitted from another mobile phone (in this case, the mobile phone 4) by the radio relay radio circuit 36 via the radio relay antenna 33, and the received radio signal is addressed to itself. Therefore, the control circuit 37 performs predetermined reception processing.

  On the other hand, the signal transmitted from the mobile phone 5 to the other terminal is received by the radio relay radio circuit 36 via the radio relay antenna 33 of the mobile phone 4, and the received radio signal is controlled by the control circuit 37. And is transmitted again from the radio wave relay radio circuit 36 of the mobile phone 4 to the mobile phone 3 via the radio wave relay antenna 33 (that is, operates as a relay station).

  Since the mobile phone 3 is located in the wireless zone of the base station 1, wireless communication is performed with the base station 1 using the mobile communication antenna 31, and with other mobile phones (here, the mobile phone 4). In between, radio wave relay is performed using the radio wave relay antenna 33. Therefore, the mobile phone 3 receives the transmission signal addressed to the other terminal from the mobile phone 5 relayed by the mobile phone 4 and receives the transmission signal via the radio relay antenna 33 by the radio relay radio circuit 36, and then performs control. Under the control of the circuit 37, radio transmission is performed to the base station 1 via the radio circuit 34 and the mobile communication antenna 31. The base station 1 transmits a transmission signal addressed to the other terminal from the received mobile phone 5 to the other terminal via a public network or the like as in the conventional mobile phone system.

  Thus, even if the mobile phone that is the mobile communication terminal of the present embodiment is located outside of the base station radio zone, it is in contact with the mobile phone located within the base station radio zone. When another mobile phone of the present embodiment exists within the radio wave relayable distance range, communication with the base station can be performed using the other mobile phone as a relay station, and the base station It is possible to perform mobile communication with a partner terminal by intervening. As a result, even if other mobile phones are outside the area of the wireless zone of the nearest base station, it is possible to communicate as if they are actually within the area of the nearest base station, and the area can be expanded easily. You can also reduce the number.

  In this embodiment, since the mobile phone 4 serving as a relay station is located outside the radio zone of the base station 1, direct wireless communication with the base station 1 is not possible. When the mobile phone is located in the radio zone of another base station, it can also be used as a relay station, and at the same time, it can communicate with another base station and perform telephone communication with the other terminal. Thus, the mobile communication terminal is different from that of a conventional ad hoc network. Furthermore, in this embodiment, since the mobile phone itself has a radio wave relay function, the number of installed base stations can be reduced in areas where the base stations are required.

  Next, a handover system using the mobile communication terminal of the present invention will be described. FIG. 2 shows a system configuration diagram of an embodiment of the handover system according to the present invention. In the figure, an artificial satellite 10 has a function of communicating with a mobile communication terminal, and is transmitted from the mobile communication terminal, the position information of the mobile communication terminal, the moving direction, the moving speed, the base station in communication Based on the received information and the like, based on this information, the fading area in the moving direction of the mobile communication terminal is recognized, and based on the information, the information such as the timing for handover and the handover destination base station is returned to the mobile communication terminal. And transmission means.

  The artificial satellite 10 needs to newly launch a plurality of artificial satellites 10 having the same configuration on a low-circular orbit like the existing GPS satellite, but the existing GPS satellite may be modified or stationary. It may be launched in orbit.

  In FIG. 2, base stations 11, 12 and 13 have their own wireless zones 14, 15 and 16, respectively, and are connected to mobile communication terminals (in this case, mobile phone 21 etc.) located in their own wireless zone. It has the same function as that of a conventional base station in that it has a wireless communication function. Here, it is assumed that an obstacle 18 exists in the vicinity of the base station 12, thereby causing a fading area 17 in which no radio zone exists between the base station 12 and the base station 13.

  In this state, the mobile phone 21 having the configuration shown in FIG. 3 located in the wireless zone 14 of the base station 11 moves in the direction of the wireless zone 16 of the base station 13 while talking to the partner terminal via the base station 11. In this case, the mobile phone 21 acquires its own location information by the information acquisition unit 42 (for example, it may be obtained by calculation by receiving a GPS signal, or may be calculated from the location information of the base station 11 that requested the location registration. Or may be calculated based on the difference in electric field strength between a plurality of base stations and the position information of those base stations), and, for example, using a sensor, the moving direction and the moving speed Further, the base station information (position and other information) of the base station 11 currently in communication is acquired, and these various pieces of information are transmitted from the satellite signal transceiver 35 to the satellite under the control of the control circuit 37 in FIG. Via the antenna 32 It is transmitted to the artificial satellite 10.

  Upon receiving this signal, the artificial satellite 10 detects the fading area 17 existing in the moving direction of the mobile phone 21 based on the received information and the information in the wireless zone of the destination base station 13, and this Handover information in the fading area 17 is generated and returned to the mobile phone 21 that is the transmission source. The cellular phone 21 receives the above handover information transmitted from the artificial satellite by the satellite signal transmitter / receiver 35 via the satellite antenna 32 and stores it in the storage unit 40 via the control circuit 37.

  When the mobile phone 21 enters the wireless zone 15 of the base station 12, the mobile phone 21 is normally handed over to the base station 12, but since the mobile phone 21 has a fading area 17 due to an obstacle 18 at the destination, communication is performed. Degradation can be caused. Therefore, since the handover information transmitted from the artificial satellite 10 instructs the base station 13 not in the base station 12 but in a good radio wave condition to perform handover, the mobile phone 21 is based on the handover information, When entering the wireless zone 15, the base station 13 is handed over.

  Here, the inside of the wireless zone 15 is outside the range of the wireless zone 16 of the base station 13, but the mobile phone 22 having the configuration of FIG. 3 located in the wireless zone 16 operates as the relay station, and the inside of the wireless zone 15 The mobile phone 21 that is moving at the position A performs wireless communication with the base station 13 via the mobile phone 22. Thereafter, the mobile phone 21 that is moving at the position B in the fading area 17 wirelessly communicates with the base station 13 via the mobile phone 22 or 23 and is at the position C in the fading area 17. The mobile phone 21 that is moving enters the wireless zone 16 by wireless communication with the base station 13 via the mobile phone 22, 23, or 24. The mobile phone 21 entering the wireless zone 16 performs direct wireless communication with the base station 13.

  Since conventional handover performs handover based on the strength of transmission power from the base station, communication may suddenly deteriorate. In this embodiment, the fading area 17 existing in the moving direction is recognized, Since handover for selecting communication with the optimal base station corresponding to the fading area 17 can be performed, it is effective even under an environment where communication interruption due to communication quality degradation such as fading is likely to occur. Handover can be performed and communication quality can be improved. Further, even if the fading area 17 changes in real time, the present invention can cope with it based on information from the mobile communication terminal.

  In the above-described embodiment, the mobile phone has been described. However, the present invention is not limited to this. For example, a simple mobile phone (PHS) or a portable information device (PDA; Personal Digital Assistants). The present invention can also be applied to other portable communication terminals such as).

It is explanatory drawing of the relay function by the portable communication terminal of this invention. 1 is a system configuration diagram of an embodiment of a handover system of the present invention. It is a block diagram of one embodiment of a portable communication terminal of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11, 12, 13 Base station 2-5, 21-24 Cellular phone 10 Artificial satellite 14-16 Radio zone 17 Fading area 18 Obstruction 31 Mobile communication antenna 32 Satellite antenna 33 Radio relay antenna 34 Radio circuit 35 Satellite Signal transmitter / receiver 36 Radio relay radio circuit 37 Control circuit 38 Operation unit 39 Display unit 40 Storage unit 41 Transmission / reception unit 42 Information acquisition unit

Claims (3)

In a mobile communication terminal comprising a first communication means for wireless communication with the nearest base station, and performing mobile communication with a counterpart terminal connected to the base station via a network,
When a transmission signal of an arbitrary transmission destination wirelessly transmitted from another portable communication terminal is received, and the transmission destination of the reception signal is not its own terminal, the reception signal is relayed to the transmission destination as it is, and the received other When the transmission destination of the transmission signal wirelessly transmitted from the mobile communication terminal is the own terminal, the second communication means for processing the received signal without performing the relay transmission ,
A third communication means for communicating with the artificial satellite;
An acquisition means for acquiring position information and movement information of the terminal itself and information of the base station in communication;
The acquired position information and movement information and information on the base station in communication are transmitted to the artificial satellite via the third communication means, and transmitted from the artificial satellite received via the third communication means. Based on handover information to be handed over to a base station having a radio zone capable of good communication among the radio zones of a plurality of base stations adjacent to a fading area in the moving direction indicated by the movement information. Another mobile communication terminal located in the wireless zone of a base station having a wireless zone capable of performing the good communication by selecting the first communication means or the second communication means during communication with a terminal. And a control means for performing wireless communication with the base station as a relay station . Wireless communication is performed between a plurality of base stations each having a unique wireless zone and an arbitrary base station having a wireless zone within the plurality of base stations, and the arbitrary base station via a network A handover system comprising a mobile communication terminal that performs mobile communication with a connected partner terminal, and an artificial satellite that communicates with the mobile communication terminal,
The mobile communication terminal is
A first communication means for wireless communication with the nearest base station;
When a transmission signal of an arbitrary transmission destination wirelessly transmitted from another portable communication terminal is received, and the transmission destination of the reception signal is not its own terminal, the reception signal is relayed to the transmission destination as it is, and the received other When the transmission destination of the transmission signal wirelessly transmitted from the mobile communication terminal is the own terminal, the second communication means for processing the received signal without performing the relay transmission ,
A third communication means for communicating with the artificial satellite;
An acquisition means for acquiring position information and movement information of the terminal itself and information of the base station in communication;
The acquired position information and movement information and information on the base station in communication are transmitted to the artificial satellite via the third communication means, and transmitted from the artificial satellite received via the third communication means. Based on handover information to be handed over to a base station having a radio zone capable of good communication among the radio zones of a plurality of base stations adjacent to a fading area in the moving direction indicated by the movement information. Another mobile communication terminal located in the wireless zone of a base station having a wireless zone capable of performing the good communication by selecting the first communication means or the second communication means during communication with a terminal. Control means for performing wireless communication with the base station as a relay station , the artificial satellite,
Receiving means for receiving the location information and movement information transmitted from the mobile communication terminal and information of the base station in communication;
Handover information generating means for generating the handover information based on at least the received position information and movement information, information on the base station in communication, and information on a base station in the movement direction indicated by the movement information;
A handover system comprising: transmission means for responding and transmitting the generated handover information to the mobile communication terminal. When the mobile communication terminal is not in the radio zone of the handover destination base station, the mobile communication terminal uses the second communication means provided in another mobile communication terminal in the radio zone of the handover destination base station. 3. The handover system according to claim 2 , wherein the other mobile communication terminal is used as a relay station to perform radio communication with the handover destination base station.

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