JP2011071931A - Communication terminal, base station, and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for shortening time for preventing user data from being transmitted and received between a portable terminal and a base station. <P>SOLUTION: The portable terminal 1 includes: a next-generation-system radio communication part 21 for communicating with the base station 2 in a radio frequency band of a next-generation PHS; and a current-system radio communication part 42 for communicating with the base station 2 by a radio frequency band of a current PHS. The portable terminal 1 continuously transmits and receives the user data to and from the base station 2 by the next-generation-system radio communication part 21 from the time of identification of the base station 2 of a new connection destination by a current-system radio communication part 22 to the time of setting for establishing communication connection to the base station 2 of the new connection destination. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication terminal that performs communication using signals of a plurality of different radio frequency bands, a base station that performs communication with the communication terminal, and a communication system including them.

  Like a mobile phone, a communication terminal may communicate with a base station while moving. In such a case, if the communication terminal leaves the base station in communication, the communication quality between the communication terminal and the base station deteriorates. If the communication terminal further moves away, the communication terminal cannot communicate with the base station. In order to prevent this, communication terminals such as the current PHS (Personal Handyphone System) and next-generation PHS, if the communication quality with the base station communicating with itself deteriorates, An operation of switching from the base station to another base station with good communication quality, so-called handover is performed. Patent Documents 1 and 2 disclose techniques related to handover. Non-Patent Document 1 discloses the current PHS, and Non-Patent Document 2 discloses the next-generation PHS.

Special table 2008-514034 gazette JP 2009-124740 A

ARIB STD-28 5.3 edition ARIB STD-T95 Version 1.1

  When handover is performed between the communication terminal and the base station, it is desirable that the time during which user data cannot be transmitted and received between the communication terminal and the base station is as short as possible.

  Therefore, the present invention has been made in view of the above points, and an object of the present invention is to provide a technique capable of shortening a time during which a communication terminal and a base station cannot transmit / receive user data to / from each other.

  In order to solve the above problems, a communication terminal according to the present invention includes: a plurality of wireless communication units that communicate with a base station using signals in a plurality of radio frequency bands that do not overlap each other; A first detection unit that detects communication quality between a first wireless communication unit that communicates with a base station using a signal of one radio frequency band, and a base station with which the first wireless communication unit is communicating; Of the plurality of radio communication units, a second radio communication unit that communicates with a base station using a signal in a second radio frequency band other than the first radio frequency band, and a base on which the second radio communication unit is communicating A communication between the first wireless communication unit and the base station when determining that the communication quality detected by the first detection unit and the second detection unit for detecting the communication quality with the station do not satisfy the standard Communication between the second wireless communication unit and the plurality of base stations And the second wireless communication unit and the new connection in a state in which communication between the first wireless communication unit and the base station is maintained. First connection establishing means for performing a first setting for establishing a communication connection with a previous base station by causing the second wireless communication unit to communicate with the new base station; After one setting is made, a communication connection is established between the first wireless communication unit and the new connection destination base station while communication between the first wireless communication unit and the base station is maintained. Second connection establishing means configured to cause the second wireless communication unit to communicate with the new connection destination base station, and after the second setting is performed, the first wireless Disconnect the communication between the communication unit and the base station, and connect the new connection destination to the first wireless communication unit. And a first communication control means to perform communication with the base station.

  In one aspect of the communication device according to the present invention, after the first setting is performed, the second wireless communication unit communicates with the new connection destination base station from the new connection destination base station. Communication enable / disable information indicating whether communication connection with the first wireless communication unit is possible is received, and the communication enable / disable information indicates that the communication connection between the new connection destination base station and the first wireless communication unit is When indicating that it is possible, the second setting is performed, and the first communication control unit disconnects communication between the first radio communication unit and the base station, and the first radio communication unit To communicate with the new connection destination base station, and the communication availability information indicates that communication connection between the new connection destination base station and the first wireless communication unit is not possible, After the first setting is performed, the communication between the first wireless communication unit and the base station is disconnected, Further comprising a second communication control means for said to perform communication with the new connection destination base station to the serial second wireless communication unit.

  In addition, a communication terminal according to the present invention includes a plurality of radio communication units that communicate with a base station using signals in a plurality of radio frequency bands that do not overlap with each other, and the first radio frequency band among the plurality of radio communication units. A first wireless communication unit that communicates with a base station using a signal; a first detection unit that detects communication quality between the base station with which the first wireless communication unit is communicating; and the plurality of wireless communication units Between the second radio communication unit that communicates with the base station using a signal in the second radio frequency band other than the first radio frequency band, and the base station with which the second radio communication unit is communicating A first detection unit that detects communication quality, and a first base station that is detected by the first detection unit and that communicates with the base station capable of communicating using signals in the first and second radio frequency bands. When it is determined that the communication quality with the wireless communication unit does not satisfy the standard, the first Base station specifying means for specifying a new connection destination base station based on communication quality between the second wireless communication unit and the plurality of base stations while maintaining communication between the line communication unit and the base station And setting for establishing a communication connection between the second wireless communication unit and the new connection destination base station in a state where communication between the first wireless communication unit and the base station is maintained, A connection establishing means for making the second wireless communication unit communicate with the new connection destination base station, and after the setting is made, disconnecting the communication between the first wireless communication unit and the base station, Communication control means for causing the second wireless communication unit to communicate with the new connection destination base station.

  In one aspect of the communication device according to the present invention, the first wireless communication unit and the second wireless communication unit communicate with a base station using different communication standards.

  Moreover, the base station which concerns on this invention is a base station which communicates with the communication terminal of Claim 1, Comprising: The several base station which communicates with the said communication terminal using the signal of several radio frequency bands which do not mutually overlap Side radio communication unit and a base station side control unit that controls the plurality of base station side radio communication units, the plurality of base station side radio communication units using the signals of the first radio frequency band, A first base station-side radio communication unit that communicates with a communication terminal; and a second base station-side radio communication unit that communicates with the communication terminal using a signal in the second radio frequency band, the base of the communication terminal When the base station is specified as the new connection destination base station by the station specifying means, the base station-side control unit is configured such that when the communication terminal performs the first setting, the second base station Communication between the station side wireless communication unit and the second wireless communication unit of the communication terminal Setting for establishing a connection is performed by causing the second base station side wireless communication unit to communicate with the second wireless communication unit of the communication terminal, and when the communication terminal performs the second setting, A setting for establishing a communication connection between the first base station side radio communication unit and the first radio communication unit of the communication terminal is set in the second base station side radio communication unit in the second of the communication terminal. The first communication control means of the communication terminal disconnects communication between the first wireless communication unit and a base station, and makes the new connection to the first wireless communication unit. When communicating with the previous base station, the first base station side wireless communication unit is caused to communicate with the first wireless communication unit of the communication terminal.

  Moreover, the base station which concerns on this invention is a base station which communicates with the communication terminal of Claim 2, Comprising: The several base station which communicates with the said communication terminal using the signal of several radio frequency bands which do not mutually overlap Side radio communication unit and a base station side control unit that controls the plurality of base station side radio communication units, the plurality of base station side radio communication units using the signals of the first radio frequency band, A first base station-side radio communication unit that communicates with a communication terminal; and a second base station-side radio communication unit that communicates with the communication terminal using a signal in the second radio frequency band, the base of the communication terminal When the base station is specified as the new connection destination base station by the station specifying means, the base station-side control unit is configured such that when the communication terminal performs the first setting, the second base station Communication between the station side wireless communication unit and the second wireless communication unit of the communication terminal Setting for establishing a connection is performed by causing the second base station side wireless communication unit to communicate with the second wireless communication unit of the communication terminal, and when the communication terminal performs the second setting, A setting for establishing a communication connection between the first base station side radio communication unit and the first radio communication unit of the communication terminal is set in the second base station side radio communication unit in the second of the communication terminal. The first communication control means of the communication terminal disconnects communication between the first wireless communication unit and a base station, and makes the new connection to the first wireless communication unit. When communicating with the previous base station, the first base station side radio communication unit communicates with the first radio communication unit of the communication terminal, and the base station side control unit receives the second By the base station side radio communication unit, the second radio communication unit of the communication terminal Then, the base station side control unit transmits the communication enable / disable information, and the second communication control unit of the communication terminal disconnects the communication between the first wireless communication unit and the base station, When making the radio communication unit communicate with the new connection destination base station, the second base station side radio communication unit is made to communicate with the second radio communication unit of the communication terminal.

  A communication system according to the present invention includes a communication terminal and a plurality of base stations, and the communication terminal communicates with the base station using signals in a plurality of radio frequency bands that do not overlap each other. And a first wireless communication unit that communicates with a base station using a signal of a first wireless frequency band among the plurality of wireless communication units, and a base station with which the first wireless communication unit is communicating A first detection unit that detects communication quality; a second wireless communication unit that communicates with a base station using a signal in a second radio frequency band other than the first radio frequency band among the plurality of radio communication units; When determining that the communication quality detected by the second detection unit that detects communication quality with the base station with which the second wireless communication unit is communicating, and the communication quality detected by the first detection unit does not satisfy the standard, In a state where communication between the first wireless communication unit and the base station is maintained, the second wireless communication unit Based on the communication quality between the communication unit and the plurality of base stations, the base station specifying means for specifying a new connection destination base station and the communication between the first wireless communication unit and the base station are maintained. In a state, the first setting for establishing a communication connection between the second wireless communication unit and the new connection destination base station is set in the second wireless communication unit with the new connection destination base station. A first connection establishing means configured to communicate with the first wireless communication unit and the new wireless communication unit in a state in which communication between the first wireless communication unit and the base station is maintained after the first setting is performed; Second connection establishing means for performing a second setting for establishing a communication connection with a base station of a new connection destination by causing the second wireless communication unit to communicate with the new base station of the connection destination; After the second setting is performed, communication between the first wireless communication unit and the base station is disconnected. , And a communication control unit for causing the communication with the new connection destination base station to the first radio communication unit.

  Further, in one aspect of the communication system according to the present invention, the communication terminal is configured such that after the base station specifying unit specifies the new connection destination base station, the communication control unit includes the first wireless communication unit. Before the first wireless communication unit communicates with the new connection destination base station, and the network to which the plurality of base stations are connected and the connection destination Communication between the communication terminal and the network is established by performing communication with the base station and communicating between the connection destination base station and the communication terminal. Do.

  Further, in one aspect of the communication system according to the present invention, after the second setting is performed, the communication control unit disconnects communication between the first wireless communication unit and the base station. Before the first wireless communication unit communicates with the new connection destination base station, the network includes a base station with which the first wireless communication unit is communicating, and the connection destination base. A base station that transmits the same user data to a station, and the base station with which the first wireless communication unit is communicating transmits user data from the network to the first wireless communication unit of the communication terminal, and the connection The previous base station transmits user data from the network to the second wireless communication unit of the communication terminal.

  A communication system according to the present invention includes a communication terminal and a plurality of base stations, and the communication terminal communicates with the base station using signals in a plurality of radio frequency bands that do not overlap each other. And a first wireless communication unit that communicates with a base station using a signal of a first wireless frequency band among the plurality of wireless communication units, and a base station with which the first wireless communication unit is communicating A first detection unit that detects communication quality; a second wireless communication unit that communicates with a base station using a signal in a second radio frequency band other than the first radio frequency band among the plurality of radio communication units; and A second detection unit that detects communication quality with a base station with which the second wireless communication unit is communicating, and signals in the first and second radio frequency bands detected by the first detection unit are used. Between the base station that can communicate with the base station and the first wireless communication unit that communicates with the base station. Based on the communication quality between the second radio communication unit and the plurality of base stations in a state where communication between the first radio communication unit and the base station is maintained when it is determined that the communication quality does not satisfy the standard. The base station specifying means for specifying the base station of the new connection destination, and the communication between the first radio communication unit and the base station are maintained, and the second radio communication unit and the new connection destination After establishing the connection establishment means for performing the setting for establishing a communication connection with the base station by causing the second wireless communication unit to communicate with the new connection destination base station, Communication control means for disconnecting communication between the first radio communication unit and the base station and causing the second radio communication unit to communicate with the new connection destination base station.

  Further, in one aspect of the communication system according to the present invention, the communication terminal is configured such that after the base station specifying unit specifies the new connection destination base station, the communication control unit includes the first wireless communication unit. Before the second wireless communication unit communicates with the new connection destination base station, and the network to which the plurality of base stations are connected and the connection destination Communication between the communication terminal and the network is established by performing communication with the base station and communicating between the connection destination base station and the communication terminal. Do.

  Further, in one aspect of the communication system according to the present invention, the communication terminal causes the communication control means to disconnect communication between the first radio communication unit and a base station, and to the second radio communication unit. Before communicating with a connected base station, the network transmits the same user data to the base station with which the first wireless communication unit is communicating and the connected base station. The base station with which the first wireless communication unit is communicating transmits user data from the network to the first wireless communication unit of the communication terminal, and the connection-destination base station is configured to transmit the user data from the communication terminal. User data from the network is transmitted to the second wireless communication unit.

  ADVANTAGE OF THE INVENTION According to this invention, the time when a communication terminal and a base station cannot transmit / receive user data mutually can be shortened.

1 is a diagram showing a communication system according to Embodiment 1. FIG. It is a figure explaining the problem of a hand-over. 3 is a block diagram showing a configuration of a mobile terminal according to Embodiment 1. FIG. 3 is a block diagram showing a configuration of a base station according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of the communication system according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of the communication system according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of the communication system according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of the communication system according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of the communication system according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of the communication system according to Embodiment 1. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the first embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the first embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the first embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the first embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the first embodiment. FIG. 6 is a diagram for explaining an operation of a communication system according to a second modification of the first embodiment. FIG. 6 is a diagram for explaining an operation of a communication system according to a second modification of the first embodiment. FIG. 6 is a diagram for explaining an operation of a communication system according to a second modification of the first embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to Embodiment 2. FIG. 6 is a diagram for explaining the operation of a communication system according to Embodiment 2. FIG. 6 is a diagram for explaining the operation of a communication system according to Embodiment 2. FIG. 6 is a diagram for explaining the operation of a communication system according to Embodiment 2. FIG. 6 is a diagram for explaining the operation of a communication system according to Embodiment 2. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the second embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the second embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the second embodiment. FIG. 6 is a diagram for explaining the operation of a communication system according to a first modification of the second embodiment. FIG.

<Embodiment 1>
FIG. 1 is a diagram showing a communication system according to an embodiment of the present invention. The communication system includes a mobile terminal 1 that is a communication terminal and a plurality of base stations 2. In FIG. 1, a plurality of base stations 2A, 2B, and 2C among the plurality of base stations 2 are shown. The mobile terminal 1 is, for example, a mobile phone or a PDA (Personal Digital Assistant). Each of the plurality of base stations 2 can perform wireless communication with the mobile terminal 1. Each communicable range 3 of the plurality of base stations 2 partially overlaps with the communicable range 3 of the adjacent base station 2. In the example of FIG. 1, the communicable range 3A of the base station 2A and the communicable range 3B of the base station 2B partially overlap, and the communicable range 3B of the base station 3B and the communicable range 3C of the base station 2C are There is a partial overlap. Each of the plurality of base stations is connected to the network 4.

  Here, when the mobile terminal 1 communicating with the base station 2A moves in the direction of arrow a in FIG. 1, the mobile terminal 1 moves away from the base station 2A. Communication quality with 2A, for example, FER (Frame Error Rate), RSSI (Received Signal Strength Indication), SINR (Signal to Interference plus Noise Ratio) and the like deteriorate. Furthermore, if the mobile terminal 1 moves in the direction of arrow a and moves outside the communicable range 3A of the base station 2A, the mobile terminal 1 cannot communicate with the base station 2A. Therefore, when the communication quality between the mobile terminal 1 and the base station 2A deteriorates, the connection destination of the mobile terminal 1 is the base station having the best communication quality with the mobile terminal 1 among the plurality of base stations 2 Switch to 2. Hereinafter, the base station 2 in which communication with the mobile terminal 1 is disconnected by switching the connection destination of the mobile terminal 1 may be referred to as an initially connected base station.

  The operation described above is the same as a generally known handover operation. Next, the problem of handover will be described with reference to FIG. FIG. 2 is a timing chart showing a connection sequence when the connection destination of the mobile terminal 51 is switched from the base station 52A to another base station in the communication system compared with the communication system according to the present embodiment. The communication system shown in FIG. 2 assumes a next-generation PHS handover.

  First, in step s51, the portable terminal 51 transmits / receives user data, such as video data and audio data, to be transmitted / received to / from other terminals via the base station 52A. In step s51, the mobile terminal 51 detects the communication quality between itself and the base station 52A. If it is determined in step s52 that the communication quality does not satisfy the standard, the portable terminal 51 transmits ANCH (Anchor Channel) / CSCH (Circuit Switching Channel) switching request information to the base station 52A in step s53. .

  In step s54, when the portable terminal 51 receives the ANCH / CSCH switching instruction information from the base station 52A, the portable terminal 51 transmits connection release information to the base station 52A. When the base station 52A receives the connection release information from the portable terminal 51, the base station 52A transmits the connection release approval information. As a result of this transmission / reception, communication between the portable terminal 51 and the base station 52A is disconnected in step s55. Then, in step s56, the mobile terminal 51 detects the communication quality between the mobile terminal 51 and the plurality of base stations, and specifies the base station with the best communication quality as the new connection destination base station. Here, the portable terminal 51 will be described below assuming that the base station 52B is specified as a new connection destination base station.

  Next, in step s57, the mobile terminal 51 and the base station 52B specified in step s56 perform the next-generation PHS connection sequence, that is, initial setting of communication connection, in order to enable user data to be transmitted and received. Do. Thereafter, if the mobile terminal 51 transmits the ANCH / CSCH switching confirmation information to the base station 52B, the mobile terminal 51 and the base station 52B can transmit / receive user data to / from each other in step s58.

  In the above handover, the mobile terminal 51 cannot transmit / receive user data to / from any base station until after executing step s55 and before executing step s58. Therefore, there is a problem that a part of user data received by the mobile terminal 1 is lost or the communication is delayed. Therefore, in the present embodiment, there is provided a technique for shortening the time during which the mobile terminal 1 and the base station 2 cannot transmit / receive user data to / from each other.

  FIG. 3 is a block diagram showing a configuration of mobile terminal 1 according to the present embodiment. The portable terminal 1 includes a transmission / reception antenna 11, a next generation wireless unit 12, a next generation wireless control unit 13, a next generation wireless detection unit 14, a transmission / reception antenna 15, a current wireless communication unit 16, and a current wireless communication. A control unit 17, a current method detection unit 18, and a control unit 25 that comprehensively controls them are provided.

  The portable terminal 1 uses a next-generation wireless communication unit 21 including a transmission / reception antenna 11, a next-generation method wireless unit 12, and a next-generation method wireless control unit 13, which are indicated by a broken line in FIG. Wireless communication is performed with the base station 2.

  Specifically, the next generation radio control unit 13 transmits the data output from the control unit 25 so that the next generation radio unit 12 transmits the data from the transmission / reception antenna 11 to the base station 2 according to the next generation PHS. The next-generation radio unit 12 is controlled according to the generation PHS protocol. The next generation radio unit 12 modulates a carrier wave based on the data from the control unit 25 input through the next generation radio control unit 13, and generates the modulated carrier wave as a signal. Then, the next-generation radio unit 12 performs amplification processing and up-conversion on the generated signal to generate a signal with a frequency band of 2.5 GHz and a bandwidth of 10 MHz, and the generated signal is transmitted to the transmission / reception antenna 11. To the base station 2.

  Further, the next generation wireless controller 13 is configured so that the next generation wireless controller 12 outputs the data included in the signal received by the transmission / reception antenna 11 to the controller 25 according to the next generation PHS. The next-generation radio unit 12 is controlled as follows. The next-generation radio unit 12 performs down-conversion and amplification processing on a signal received via the transmission / reception antenna 11 and having a frequency band of 2.5 GHz and a bandwidth of 10 MHz. Then, the next-generation radio unit 12 demodulates the signal obtained thereby, acquires data included in the signal, and outputs the acquired data to the control unit 25 via the next-generation radio control unit 13. To do.

  The mobile terminal 1 uses the current method wireless communication unit 22 including the transmission / reception antenna 15, the current method wireless unit 16 and the current method wireless control unit 17 indicated by a broken line in FIG. With station 2

  Specifically, the current method wireless control unit 17 transmits the data output from the control unit 25 so that the current method wireless communication unit 22 transmits the data from the transmission / reception antenna 15 to the base station 2 according to the current PHS. The current radio unit 16 is controlled according to the protocol. The current system radio unit 16 modulates a carrier wave based on the data from the control unit 25 input through the current system radio control unit 17, and generates the modulated carrier wave as a signal. Then, the current system radio unit 16 generates a signal having a frequency band of 1.9 GHz and a bandwidth of 900 KHz or 300 KHz by performing amplification processing and up-conversion on the generated signal, and transmits the generated signal to the transmission / reception antenna. 15 to the base station 2.

  Further, the current mode radio control unit 17 is configured so that the current mode radio unit 16 outputs the data included in the signal received by the transmission / reception antenna 15 to the control unit 25 according to the current PHS mode, according to the current PHS protocol. The radio unit 16 is controlled. The current system radio unit 16 performs down-conversion and amplification processing on a signal having a frequency band of 1.9 GHz and a bandwidth of 900 KHz or 300 KHz received via the transmission / reception antenna 15. Then, the current system radio unit 16 demodulates the signal obtained thereby, acquires data included in the signal, and outputs the acquired data to the control unit 25 via the current radio control unit 17.

  Since the next generation wireless communication unit 21 and the current wireless communication unit 22 are configured as described above, the current wireless communication unit 22 is used by the next wireless communication unit 21 for communication with the base station 2. The base station 2 communicates using a radio frequency band other than the radio frequency band to be transmitted. That is, among the two radio frequency bands that do not have overlapping portions, the current wireless communication unit 22 communicates with the base station 2 using one, and the next-generation wireless communication unit 21 uses the other. Communicate with the base station 2. Therefore, even if the communication between the next generation wireless communication unit 21 and the base station 2 and the communication between the current wireless communication unit 22 and the base station 2 are performed simultaneously, they do not interfere with each other.

  The next-generation scheme detection unit 14 shown in FIG. 3 is based on the signal received by the next-generation scheme radio unit 12 through the transmission / reception antenna 11, and communication quality between the next-generation scheme radio communication unit 21 and the base station 2, for example, FER, RSSI, SINR are detected. The current method detection unit 18 detects communication quality between the current method wireless communication unit 22 and the base station 2, for example, FER, RSSI, SINR, based on the signal received by the current method wireless unit 16 through the transmission / reception antenna 15. To do.

  The control unit 25 is configured by a CPU or the like, generates data such as user data, and outputs the generated data to at least one of the next generation wireless control unit 13 and the current wireless control unit 17. The control unit 25 configured by a CPU or the like executes an operation program stored in a storage unit (not shown) of the mobile terminal 1, thereby causing the control unit 25 to have a base station specifying unit 25 a and next-generation connection establishment unit. 25b, next-generation system communication control means 25c, current system connection establishment means 25d, and current system communication control means 25e for performing communication of the current PHS are formed as functional blocks. The base station specifying means 25a specifies the base station 2 that is a new connection destination of the mobile terminal 1. The next generation method connection establishment means 25b performs setting for establishing a communication connection between the next generation method wireless communication unit 21 and the new connection destination base station 2. The next generation communication control means 25c causes the next generation wireless communication unit 21 to communicate with the new connection destination base station 2. The current method connection establishment means 25d performs setting for establishing a communication connection between the current method wireless communication unit 22 and the new connection destination base station 2. The current mode communication control means 25e causes the current mode radio communication unit 22 to communicate with the new connection destination base station 2.

  Next, the configuration of the base station 2 will be described. FIG. 4 is a block diagram showing a configuration of base station 2 according to the present embodiment. In the present embodiment, each of the plurality of base stations 2 employs the block configuration shown in FIG.

  The base station 2 controls the transmission / reception antenna 31, the next generation radio unit 32, the next generation radio control unit 33, the transmission / reception antenna 34, the current radio unit 35, and the current radio control unit 36. The control part 45 which controls automatically. The control unit 45 transmits / receives user data to / from the network 4. The control unit 45 outputs data such as user data from the network 4 to at least one of the next-generation wireless control unit 33 and the current wireless control unit 36.

  The base station 2 uses a next-generation PHS using a next-generation radio communication unit 41 including a transmission / reception antenna 31, a next-generation radio unit 32, and a next-generation radio control unit 33, which are indicated by broken lines in FIG. Wireless communication is performed with the mobile terminal 1. Specific operations of the transmission / reception antenna 31, the next generation radio unit 32, and the next generation radio control unit 33 are the same as the operations of the transmission / reception antenna 11, the next generation radio unit 12, and the next generation radio control unit 13 of the mobile terminal 1. Each is the same. However, the transmission / reception antenna 11, the next generation radio unit 12, and the next generation radio control unit 13 of the mobile terminal 1 adopt a configuration suitable for the mobile terminal 1 to perform radio communication, whereas The antenna 31, the next generation radio unit 32, and the next generation radio control unit 33 adopt a configuration suitable for the base station 2 to perform radio communication.

  In addition, the mobile terminal 1 uses the current method wireless communication unit 42 including the transmission / reception antenna 34, the current method wireless unit 35, and the current method wireless control unit 36, which is indicated by a broken line in FIG. Is performed with the mobile terminal 1. Specific operations of the transmission / reception antenna 34, the current method wireless unit 35, and the current method wireless control unit 36 are the same as the operations of the transmission / reception antenna 15, the current method wireless unit 16 and the current method wireless control unit 17 of the portable terminal 1, respectively. . However, the transmission / reception antenna 15, the current system radio unit 16, and the current system radio control unit 17 of the mobile terminal 1 adopt a configuration suitable for the mobile terminal 1 to perform radio communication, whereas the transmission / reception antenna 34. The current system radio unit 35 and the current system radio control unit 36 adopt a configuration suitable for the base station 2 to perform radio communication.

  Since the next-generation wireless communication unit 41 and the current wireless communication unit 42 are configured as described above, the current wireless communication unit 42 is used by the next-generation wireless communication unit 41 for communication with the mobile terminal 1. The mobile terminal 1 communicates with a radio frequency band other than the radio frequency band to be used. That is, among the two radio frequency bands that do not have overlapping portions, the current wireless communication unit 42 communicates with the mobile terminal 1 using one, and the next-generation wireless communication unit 41 uses the other. It communicates with the portable terminal 1. Therefore, the communication between the next generation wireless communication unit 41 and the next generation wireless communication unit 21 and the communication between the current wireless communication unit 22 and the current wireless communication unit 42 do not interfere with each other.

  Next, a connection sequence when the connection destination of the mobile terminal 1 is switched from one base station 2 to another one base station 2 in the communication system according to the present embodiment will be described. As an example, here, a connection sequence when the mobile terminal 1 switches the connection destination from the base station 2A to another base station will be described with reference to FIG.

  First, in step s1, the mobile terminal 1 and the base station 2A transmit / receive user data to / from each other using the next-generation radio communication units 21 and 41. The portable terminal 1 and the base station 2A maintain communication for transmitting / receiving user data to / from each other using the next-generation wireless communication units 21 and 41 until step s8 described later is executed. FIG. 6 is a diagram schematically showing the state of communication connection at this time. A solid line arrow indicates that user data is transmitted and received between the mobile terminal 1 and the base station 2, and the same is true in the following schematic diagrams. The portable terminal 1 is connected to the network 4 via the base station 2A in step s1. Moreover, the portable terminal 1 detects the communication quality between 2 A of base stations by the next generation system detection part 14 in the same step s1.

  If it is determined in step s2 that the communication quality with the base station 2A does not satisfy the standard, the mobile terminal 1 uses the next-generation radio communication unit 21 in step s3 to send the ANCH / CSCH switching request information. Transmit to the base station 2A. Generally, when the frequency used for communication changes, the communication quality related to the communication changes. Therefore, when the base station 2A receives the ANCH / CSCH switching request information from the mobile terminal 1, the base station 2A uses a frequency at which the communication quality detected by the next generation method detection unit 14 satisfies the standard for communication with the mobile terminal 1. Check if it can be used. When the base station 2A can use a frequency satisfying the communication quality standard, in step s4, the base station 2A sets information specifying the frequency and a slot (time zone) using the frequency as ANCH / CSCH switching instruction information. It transmits to the portable terminal 1. On the other hand, when the base station 2A cannot use a frequency that satisfies the communication quality, the mobile station 1 uses information indicating that an appropriate frequency does not exist in step s4 as ANCH / CSCH switching instruction information. Send to.

  When the mobile terminal 1 receives the information specifying the frequency and slot as the ANCH / CSCH switching instruction information, the mobile terminal 1 is specified without switching the connection destination of the mobile terminal 1 from the base station 2A to another base station. Communication with the base station 2A is performed in the slot specified by using the frequency. On the other hand, when the mobile terminal 1 receives information indicating that an appropriate frequency does not exist as the ANCH / CSCH switching instruction information, the mobile terminal 1 executes the steps after step s5 to set the connection destination of the mobile terminal 1 as a base. An operation of switching from the station 2A to another base station is performed.

  In step s 5, the mobile terminal 1 receives a signal periodically transmitted from each of the plurality of base stations 2 at the current wireless communication unit 22. When the reception is performed, the current method detection unit 18 of the mobile terminal 1 determines whether or not the current method wireless communication unit 22 and the current method wireless communication unit 22 based on the signals from the plurality of base stations 2 received by the current method wireless communication unit 22. Communication quality with each of the plurality of base stations 2 is detected. Then, the base station specifying unit 25a specifies, as a new connection destination, the base station 2 having the best communication quality detected by the current method detection unit 28 among the plurality of base stations 2. Here, the base station specifying means 25a of the portable terminal 1 will be described below assuming that the base station 2B is specified as a new connection destination.

  Next, in step s6, the current mode connection establishment means 25d of the mobile terminal 1 and the base station 2B specified in step s5 use the current mode wireless communication units 22 and 42 for initial setting of the next generation PHS. For the purpose of enabling data to be transmitted / received to / from each other, the current PHS connection sequence, that is, initial setting of communication connection is performed using the current wireless communication units 22 and 42. In this current PHS connection sequence, data for initial setting of the current PHS is transmitted and received between the current wireless communication unit 22 and the current wireless communication unit 42. The initial setting data for the next generation PHS is data necessary for the initial setting in the communication connection of the next generation PHS, and the initial setting data for the current PHS is the initial setting in the communication connection of the current PHS. Necessary data. FIG. 7 is a timing chart showing in detail a connection sequence performed by the mobile terminal 1 and the base station 2B in step s6 shown in FIG.

  This connection sequence includes a link channel establishment phase (steps s71 and s72) and a service channel establishment phase (steps s73 to s90). In the link channel establishment phase, a channel necessary for call connection of each service and a protocol type necessary for call connection in the service channel establishment phase are specified using the control channel. In the service channel establishment phase, using the functions set in the link channel establishment phase, a channel (service channel) necessary for providing a service and a protocol type necessary for the communication phase are specified.

  First, in step s71, the mobile terminal 1 transmits link channel establishment request information to the base station 2B. In step s72, the base station 2B that has received the link channel establishment request information searches for available frequencies and slots, and carries link channel assignment information for assigning the frequencies and slots to the current wireless communication unit 22 of the mobile terminal 1. Transmit to terminal 1.

  Then, in steps s73 and s74, the synchronization burst is transmitted / received between the mobile terminal 1 and the base station 2B, thereby synchronizing the frequency and slot used in communication between the mobile terminal 1 and the base station 2B. Taken. Then, in step s75, a SABM (Setasynchronous Balanced Mode) command is transmitted from the mobile terminal 1 to the base station 2B, thereby shifting to the multiframe confirmation type operation mode. Thereafter, in step s76, the base station 2B transmits a UA (Unnumbered Acknowledge) command to the mobile terminal 1, thereby notifying the mobile terminal 1 that the base station 2B has accepted the SABM command.

  Thereafter, in step s77, CC call setting information necessary for performing a CC (Call Control) function for controlling line call connection is transmitted from the mobile terminal 1 to the base station 2B. In step s78, the base station 2B transmits CC call setting acceptance information to the portable terminal 1 to notify the portable terminal 1 that the call setting has been accepted. Next, when the notification information reception instruction is set in the mobile terminal 1 in step s79, the mobile terminal 1 transmits the definition information request information to the base station 2B. The notification information reception instruction means that when the mobile terminal 1 transmits the link channel establishment request information (step s71), the base station 2B notifies the base station 2B of the notification state number of the area information that it owns. The station 2B is an instruction to transmit to the mobile terminal 1 before step s79 based on the notification state number. The base station 2B that has received the definition information request information transmits notification information to the mobile terminal 1 in step s80.

  Next, in step s81, RT function request information for requesting an RT (Radio Frequency Transmission Management) function for managing radio resources is transmitted from the mobile terminal 1 to the base station 2B. In step s82, the base station 2B transmits RT function request response information to the mobile terminal 1. In step s83, the mobile terminal 1 transmits RT secret key setting information including information specifying the secret key to the base station 2B.

  Next, the base station 2B transmits to the mobile terminal 1 MM function request information for requesting an MM (Mobility Management) function that supports the mobility of the mobile terminal 1 in step s84. The base station 2B transmits MM function request response information to the mobile terminal 1 in step s85. Thereafter, the base station 2B transmits MM authentication request information including information indicating an authentication random number to the mobile terminal 1 in step s86. In step s87, the portable terminal 1 performs an operation using the authentication random number from the base station 2B and the authentication key held by itself, and transmits MM authentication response information including information indicating the operation result to the base station 2B. .

  Thereafter, in step s88, a DISC (Disconnection) command is transmitted from the base station 2B to the portable terminal 1, whereby the multi-frame confirmation type operation mode ends. Then, in step s89, the mobile terminal 1 transmits a UA command to the base station 2B, thereby notifying the base station 2B that the mobile terminal 1 has accepted the DISC command. Thereafter, in step s90, CC response information is transmitted from the base station 2B to the mobile terminal 1. When step s90, which is the final step of step s6, is completed, the mobile terminal 1 and the base station 2B can transmit and receive next-generation PHS initial setting data and the like using the current wireless communication units 22 and 42. It becomes.

  Next, in step s7 shown in FIG. 5, the next generation method connection establishment means 25b and the base station 2B of the portable terminal 1 use the next generation method wireless communication units 21 and 41 to enable transmission and reception of user data to and from each other. Then, the next-generation PHS connection sequence using the current wireless communication units 22 and 42, that is, initial setting of communication connection is performed. In this next-generation PHS connection sequence, data for initial setting of the next-generation PHS is transmitted and received between the current wireless communication unit 22 and the current wireless communication unit 42. FIG. 8 is a diagram schematically showing the state of communication connection at this time. A broken arrow indicates that data for initial setting of the next generation PHS is transmitted and received between the mobile terminal 1 and the base station 2.

  FIG. 9 is a timing chart showing the connection sequence in detail. First, in step s101, the mobile terminal 1 transmits LCH (Link Channel) allocation request information to the base station 2B. In step s102, the base station 2B that has received the LCH allocation request information searches for usable frequencies and slots, and carries the LCH allocation response information for allocating the frequencies and slots to the next-generation radio communication unit 21 of the mobile terminal 1. Transmit to terminal 1.

  In step s103, the mobile terminal 1 detects the RSSI at the frequency assigned by the base station 2B, and based on the RSSI, the signal at the frequency does not receive strong interference, or the frequency can be used. If it is determined, link establishment request information indicating the start of transmission is transmitted to the base station 2B. The base station 2B that has received the link establishment request information transmits a link establishment response indicating the function used for the transmission to the mobile terminal 1 in step s104.

  Thereafter, when the special function of the LCH is required or needs to be changed, the mobile terminal 1 transmits an extended function request to the base station 2B in step s105, and the base station 2B receives the step s106. The extended function response is transmitted to the portable terminal 1. Then, in step s107, the mobile terminal 1 transmits the quality of service (QoS) connection type to the base station 2B to the base station 2B. Next, the base station 2B and the mobile terminal 1 transmit and receive authentication information in steps s108 and s109. At this time, the base station 2B receives, from the mobile terminal 1, terminal specifying information for specifying the mobile terminal 1 and base station specifying information for specifying the base station 2A, which are included in the authentication information. Then, the mobile terminal 1 transmits a secret key to the base station 2B in step s110, and the base station 2B transmits information such as the connection ID of the mobile terminal 1 and a QCS (Qos Control Session) in step s111. Is transmitted to the mobile terminal 1. When step s111, which is the final step of step s7, is finished, the terminal 1 and the base station 2B transmit / receive user data to / from each other using the next-generation radio communication units 21 and 41. Is possible.

  After step s7 shown in FIG. 5, the next generation communication control means 25c of the mobile terminal 1 disconnects the communication between the next generation wireless communication unit 21 and the base station 2A and Communicate with the station 2B. Specifically, the next generation communication control unit 25c of the mobile terminal 1 transmits the connection release information to the base station 2A using the next generation wireless communication unit 21. When the base station 2 </ b> A receives the connection release information, the base station 2 </ b> A transmits the connection release approval information to the mobile terminal 1 using the next generation wireless communication unit 41. As a result of this transmission / reception, in step s8, the communication between the next generation wireless communication unit 21 of the mobile terminal 1 and the next generation wireless communication unit 41 of the base station 2A is disconnected.

  Then, if the next generation communication control means 25c of the portable terminal 1 transmits the ANCH / CSCH switching confirmation information to the base station 2B using the next generation wireless communication unit 21, the portable terminal 1 and the base station 2B In step s9, user data can be transmitted / received to / from each other using the next-generation wireless communication units 21 and 41. In parallel with this, the mobile terminal 1 stops communication with the base station 2B via the current wireless communication unit 22. FIG. 10 is a diagram schematically showing the state of communication connection at this time.

  Thereafter, in step s10, the base station 2B determines that the mobile station 1 transmits the terminal identification information and the base station identification information transmitted when the steps s108 and s109 shown in FIG. The base station specifying information for specifying the base station 2B (hereinafter, this information may be referred to as “network connection information”) is transmitted to the network 4. Thereby, the initial setting of the communication connection between the portable terminal 1 and the network 4 via the base station 2B is performed. After this initial setting is performed, the network 4 and the mobile terminal 1 can transmit / receive user data to / from each other via the base station 2B.

  According to the communication system according to the present embodiment as described above, while the communication terminal 1 is performing the operation of specifying the new connection destination base station 2, and the mobile terminal 1 and the new connection destination base. The mobile terminal 1 and the initially connected base station 2 transmit / receive user data to / from each other by the next generation PHS even while the station 2 performs initial setting for enabling user data transmission / reception. Therefore, the time during which the mobile terminal 1 and the base station 2 cannot transmit / receive user data to each other can be shortened.

  In the present embodiment, the base station 2 to which the mobile terminal 1 is initially connected is the base station 2A having the next generation wireless communication unit 41 and the current wireless communication unit 42. However, the base station 2 may include the next-generation wireless communication unit 41 but not the current wireless communication unit 42. That is, in the first embodiment, it is only necessary that the initially connected base station 2 can communicate with the communication terminal 1 at least by the next-generation PHS. In this embodiment, the base station specifying means 25a, next-generation system connection establishment means 25b, next-generation system communication control means 25c, current system connection establishment means 25d, and current system communication control means 25e However, the present invention is not limited to this, and may be configured by separate hardware.

<Modification 1>
When the base station 2 of the new connection destination of the mobile terminal 1 uses all the frequencies that can be used for the next-generation PHS for communication with other mobile terminals 1 other than the mobile terminal 1 The portable terminal 1 and the connection-destination base station 2 cannot transmit / receive user data to / from each other using the next-generation PHS.

  Further, as in the above example, after the communication between the mobile terminal 1 and the initially connected base station 2 is disconnected, the connected base station 2 between the mobile terminal 1 and the network 4 is changed. When the communication connection is performed, the timing for starting transmission / reception of user data between the portable terminal 1 and the network 4 is delayed until the communication connection is completed.

  Therefore, the communication system according to the present modification provides a technique for improving the above points. 11, 12 and 15 are timing charts showing a connection sequence when the connection destination of the mobile terminal 1 is switched from the base station 2A to the base station 2B in the communication system according to this modification. The connection sequence when the connection destination of the mobile terminal 1 is switched from the base station 2 other than the base station 2A to the base station 2 other than the base station 2 and the base station 2B is the same.

  As shown in FIG. 11, in the communication system according to this modification, the same steps s1 to s6 as in the above-described communication system are executed. After that, in step s15, the base station 2B determines that the frequency that can be used for the next generation PHS is used for all communications with the mobile terminal 1 other than the mobile terminal 1 that requested switching in step s3. It is determined that communication connection with the next-generation wireless communication unit 21 of the terminal 1 is not possible. Otherwise, the base station 2B determines that communication connection can be established with the next-generation wireless communication unit 21 of the mobile terminal 1 that has requested switching. Then, in step s16, the base station 2B transmits communication enable / disable information indicating the determination result to the mobile terminal 1 that has requested switching using the current wireless communication unit 42.

  When the communication availability information transmitted to the mobile terminal 1 in step s16 indicates a determination result that the communication connection between the base station 2B and the next generation wireless communication unit 21 of the mobile terminal 1 is possible, the steps shown in FIG. A connection sequence consisting of s21 to s26 is executed.

  In step s21, the next generation method connection establishment means 25b and the base station 2B of the mobile terminal 1 use the next generation method wireless communication units 21 and 41 to transmit / receive user data to / from each other. , 42 is used to perform the next-generation PHS connection sequence similar to step s7. The state of communication connection at this time is the same as the state of communication connection shown in FIG. The mobile terminal 1 includes terminal specifying information for specifying the mobile terminal 1 and the base station 2A when the steps s108 and s109 shown in FIG. Is transmitted to the base station 2B using the current wireless communication unit 22.

  In step s22, the base station 2B transmits network connection information to the network 4. Thereby, the initial setting of the communication connection between the portable terminal 1 and the network 4 via the base station 2B is performed. After this initial setting is performed, the network 4 and the mobile terminal 1 can transmit / receive user data to / from each other via the base station 2B. In step s23, the network 4 transmits the same user data to be transmitted to the mobile terminal 1 to the base station 2A and the base station 2B. The base station 2 </ b> A transmits user data transmitted from the network 4 to be transmitted to the mobile terminal 1 to the mobile terminal 1 using the next-generation wireless communication unit 41. The base station 2 </ b> B transmits user data transmitted from the network 4 to be transmitted to the mobile terminal 1 to the mobile terminal 1 using the current wireless communication unit 42. As a result, the same user data is transmitted to the mobile terminal 1 from each of the base station 2A and the base station 2B. FIG. 13 is a diagram schematically showing the state of communication connection at this time.

  After step s23, the next generation communication control means 25c of the mobile terminal 1 disconnects the communication between the next generation wireless communication unit 21 and the base station 2A, and communicates with the base station 2B to the next generation wireless communication unit 21. Let it be done. Specifically, the next generation wireless communication control unit 25c of the mobile terminal 1 transmits the connection release information to the base station 2A using the next generation wireless communication unit 21. When the base station 2 </ b> A receives the connection release information, the base station 2 </ b> A transmits the connection release approval information to the mobile terminal 1 using the next generation wireless communication unit 41. As a result of the transmission / reception, in step s24, the communication between the next generation wireless communication unit 21 of the mobile terminal 1 and the next generation wireless communication unit 41 of the base station 2A is disconnected. FIG. 14 is a diagram schematically showing the state of communication connection at this time. As shown in FIG. 14, the mobile terminal 1 does not transmit / receive user data to / from the initially connected base station 2A, but continues to transmit / receive user data to / from the base station 2B.

  When the base station 2A receives the connection release information from the mobile terminal 1, in step s25, the base station 2A indicates that it stops transmission / reception of user data to be transmitted to the mobile terminal 1 between the base station 2A and the network 4. 4 to send.

  Then, if the next generation communication control means 25c of the portable terminal 1 transmits the ANCH / CSCH switching confirmation information to the base station 2B using the next generation wireless communication unit 21, the portable terminal 1 and the base station 2B In step s26, user data can be transmitted / received to / from each other using the next-generation wireless communication units 21 and 41. In parallel with this, the mobile terminal 1 stops communication with the base station 2B via the current wireless communication unit 22.

  By performing the above connection sequence shown in FIG. 12, finally, a communication connection state similar to the communication connection state shown in FIG. 10 is obtained.

  On the other hand, when the communication propriety information transmitted to the mobile terminal 1 in step s16 described above indicates a determination result that the base station 2B and the next-generation wireless communication unit 21 of the mobile terminal 1 cannot be connected, A connection sequence including steps s31 to s35 shown in FIG. 15 is executed. By executing step s6, the mobile terminal 1 and the base station 2B can already transmit and receive user data to and from each other using the current wireless communication units 22 and 42.

  In step s31, the mobile terminal 1 transmits terminal specifying information for specifying the mobile terminal 1 and base station specifying information for specifying the base station 2A to the base station 2B using the current wireless communication unit 22. In step s32, the same process as step s22 is executed, and in step 33, the same process as step 23 is executed. The state of the communication connection after executing step s33 is the same as the state of the communication connection shown in FIG. 13, and the same user data is sent from each of the base station 2A and the base station 2B to the mobile terminal 1. Sent.

  After step s33, the current mode communication control means 25e of the portable terminal 1 disconnects the next-generation mode radio communication unit 21 and the base station 2A, and causes the current mode radio communication unit 22 to communicate with the base station 2B. . Specifically, the current mode communication control unit 25e of the mobile terminal 1 transmits the connection release information to the base station 2A using the next generation mode radio communication unit 21. When the base station 2 </ b> A receives the connection release information, the base station 2 </ b> A transmits the connection release approval information to the mobile terminal 1 using the next generation wireless communication unit 41. As a result of this transmission / reception, in step s34, communication between the next generation wireless communication unit 21 of the mobile terminal 1 and the next generation wireless communication unit 41 of the base station 2A is disconnected. In parallel, the mobile terminal 1 and the base station 2B transmit and receive user data to and from each other using the current wireless communication units 22 and 42.

  By performing the above connection sequence shown in FIG. 15, finally, a communication connection state similar to the communication connection state shown in FIG. 14 is obtained. As illustrated in FIG. 14, the mobile terminal 1 does not transmit / receive user data to / from the base station 2A that is initially connected, but continues to transmit / receive user data to / from the base station 2B.

  When the base station 2A receives the connection release information from the mobile terminal 1, in step s35, the base station 2A indicates that it stops transmitting / receiving user data to be transmitted to the mobile terminal 1 between the base station 2A and the network 4. 4 to send.

  Thereafter, the mobile terminal 1 continues to communicate with the base station 2B according to the current PHS.

  According to the communication system according to the modification as described above, the communication enable / disable information can be communicated between the new connection destination base station 2 and the next-generation wireless communication unit 21 of the mobile terminal 1. , User data is transmitted and received between the new connection destination base station 2 and the next-generation wireless communication unit 21 (FIG. 10). On the other hand, when the communication availability information indicates that communication connection between the new connection destination base station 2 and the next generation wireless communication unit 21 of the mobile terminal 1 is not possible, the new connection destination User data is transmitted and received between the base station 2 and the current wireless communication unit 22 (FIG. 14). Therefore, even if the mobile terminal 1 and the connected base station 2 cannot transmit / receive user data to / from each other using the next-generation wireless communication units 21 and 41, the current wireless communication units 22 and 42 can be used by the user. Data can be sent and received from each other. Therefore, it can suppress that the portable terminal 1 and the base station 2 become unable to transmit / receive user data mutually.

  In addition, according to the communication system according to this modification, before the mobile terminal 1 and the base station 2 disconnect the communication between the next-generation wireless communication unit 21 and the next-generation wireless communication unit 41, a new connection destination The communication connection between the mobile terminal 1 and the network 4 is performed via the base station 2. Therefore, it is possible to suppress a delay in the timing at which user data transmission / reception is started between the mobile terminal 1 and the network 4.

  Further, according to the communication system according to this modification, before the mobile terminal 1 and the base station 2 disconnect the communication between the next generation wireless communication unit 21 and the next generation wireless communication unit 41, the base station 2 And the base station 2 of a new connection destination transmits the same user data to the portable terminal 1 (FIG. 13). Therefore, it is possible to suppress user data from being lost in the mobile terminal 1.

<Modification 2>
In the communication system described above, the communication terminal 1 communicates with the base station 2 using the next-generation PHS, performs initial setting of communication connection with the new base station 2 using the current PHS, After that, the next-generation PHS is used for communication with the new base station 2, but in the communication system according to this modification, the communication terminal 1 communicates with the base station 2 using the current PHS. In this state, the communication connection with the new base station 2 is initially set using the next-generation PHS, and then communication with the new base station 2 is performed using the current PHS. Hereinafter, a procedure in which the mobile terminal 1 switches the connection destination from the base station 2A to the base station 2B in the present modification will be described with reference to FIGS.

  First, as illustrated in FIG. 16, the mobile terminal 1 and the base station 2 </ b> A transmit and receive user data to and from each other using the current wireless communication units 22 and 42. Then, the mobile terminal 1 and the new connection destination base station 2B use the next-generation wireless communication units 21 and 41 to enable transmission and reception of data for initial setting of the current PHS to each other. Next-generation PHS connection sequence is performed using the wireless communication units 21 and 41.

  Then, the portable terminal 1 and the base station 2B connect the current PHS using the next-generation wireless communication units 21 and 41 for the purpose of enabling user data to be transmitted and received using the current wireless communication units 22 and 42. Perform a sequence. FIG. 17 is a diagram schematically showing the state of communication connection at this time.

  Thereafter, the communication between the current wireless communication unit 22 of the mobile terminal 1 and the current wireless communication unit 42 of the base station 2A is disconnected. Then, as shown in FIG. 18, the mobile terminal 1 and the base station 2B transmit and receive user data to and from each other using the current wireless communication units 22 and 42, and the mobile terminal 1 transmits the next-generation wireless communication unit 21. The communication with the base station 2B is stopped.

  In the above, the procedure for switching the connection destination of the mobile terminal 1 from the base station 2A to the base station 2B has been described. However, the connection destination of the mobile terminal 1 is changed from the base station 2 other than the base station 2A to the base station 2 and the base station 2B. The procedure for switching to the base station 2 other than the station 2B is the same.

  According to the communication system according to this modification as described above, while the communication terminal 1 is performing the operation of specifying the new connection destination base station 2, and the mobile terminal 1 and the new connection destination base station. The mobile terminal 1 and the initially connected base station 2 transmit and receive user data to and from each other using the current PHS, while the initial setting for enabling the user data to be transmitted and received by the mobile terminal 1 is performed. Therefore, the time during which the mobile terminal 1 and the base station 2 cannot transmit / receive user data to each other can be shortened.

  Note that in the first modification as well, in the first modification, the communication terminal 1 communicates with the base station 2 using the current PHS and uses the next generation PHS to establish a new connection destination base station 2. Initial setting of communication connection may be performed, and then communication with a new base station 2 may be performed using the current PHS or the next generation PHS.

<Embodiment 2>
In the present embodiment, a case will be described in which the communication system includes a base station (hereinafter referred to as “base station 2D”) that has the current wireless communication unit 42 but does not have the next wireless communication unit 41. . It is assumed that mobile terminal 1 according to the present embodiment has the configuration of mobile terminal 1 according to Embodiment 1.

  FIG. 19 is a timing chart showing a connection sequence when the mobile terminal 1 switches the connection destination from the base station 2A to the base station 2D. As shown in FIG. 19, in the communication system according to the present embodiment, first, step s1 described in the first embodiment is executed. FIG. 20 is a diagram schematically showing the state of communication connection at this time. Thereafter, steps s2 to s6 described in the first embodiment are executed. In step s6, the current mode connection establishment means 25d of the mobile terminal 1 and the new connection destination base station 2D use the current mode wireless communication units 22 and 42 to transmit / receive user data to / from each other. The current PHS connection sequence is performed using the system radio communication units 22 and 42.

  Then, in step s41, the mobile terminal 1 transmits terminal specifying information for specifying the mobile terminal 1 and base station specifying information for specifying the base station 2A to the base station 2D using the current wireless communication unit 22. . FIG. 21 is a diagram schematically showing the state of communication connection at this time. A dashed-dotted arrow indicates that terminal identification information and base station identification information are transmitted and received between the mobile terminal 1 and the base station 2, and the same applies to the following schematic diagrams.

  In step s42, the base station 2D transmits network connection information to the network 4. Thereby, the initial setting of the communication connection between the portable terminal 1 and the network 4 via the base station 2D is performed. After this initial setting is performed, the network 4 and the mobile terminal 1 can transmit / receive user data to / from each other via the base station 2D. In step s43, the network 4 transmits the same user data to be transmitted to the mobile terminal 1 to each of the base station 2A and the base station 2D. The base station 2 </ b> A transmits user data transmitted from the network 4 to be transmitted to the mobile terminal 1 to the mobile terminal 1 using the next-generation wireless communication unit 41. The base station 2D transmits the user data transmitted from the network 4 and to be transmitted to the mobile terminal 1 to the mobile terminal 1 using the current wireless communication unit 42. As a result, the same user data is transmitted to the mobile terminal 1 from each of the base station 2A and the base station 2D. FIG. 22 is a diagram schematically showing the state of communication connection at this time.

  After step s43, the current mode communication control unit 25e of the mobile terminal 1 disconnects the communication between the next generation mode radio communication unit 21 and the base station 2A, and causes the current mode radio communication unit 22 to communicate with the base station 2B. . Specifically, the current mode communication control unit 25e of the mobile terminal 1 transmits the connection release information to the base station 2A using the next generation mode radio communication unit 21. When the base station 2 </ b> A receives the connection release information, the base station 2 </ b> A transmits the connection release approval information to the mobile terminal 1 using the next generation wireless communication unit 41. As a result of the transmission / reception, in step s44, the communication between the next generation wireless communication unit 21 of the mobile terminal 1 and the next generation wireless communication unit 41 of the base station 2A is disconnected. In parallel, the mobile terminal 1 and the base station 2B transmit and receive user data to and from each other using the current wireless communication units 22 and 42. FIG. 23 is a diagram schematically showing the state of communication connection at this time. As shown in FIG. 23, the mobile terminal 1 does not transmit / receive user data to / from the initially connected base station 2A, but continues to transmit / receive user data to / from the base station 2D.

  When the base station 2A receives the connection release information from the mobile terminal 1, in step s45, the base station 2A indicates that it stops transmitting / receiving user data to be transmitted to the mobile terminal 1 between the base station 2A and the network 4. 4 to send.

  According to the communication system according to the present embodiment as described above, the communication terminal 1 performs an operation of specifying a new connection destination base station 2D, and the mobile terminal 1 and a new connection destination base. The mobile terminal 1 and the initially connected base station 2D transmit / receive user data to / from each other by the next-generation PHS while the station 2D performs initial setting for enabling transmission / reception of user data. Therefore, the time during which the mobile terminal 1 and the base station 2 cannot transmit / receive user data to each other can be shortened.

  In the above example of the second embodiment, the new connection destination base station 2 is the base station 2D that communicates with the communication terminal 1 using only the current PHS. The base station 2 may be a base station that communicates with the communication terminal 1 using only the next-generation PHS (hereinafter referred to as “base station 2E”). The operation of the communication system in this case will be described below with reference to FIGS.

  First, as illustrated in FIG. 24, the mobile terminal 1 and the base station 2 </ b> A transmit and receive user data to and from each other using the current wireless communication units 22 and 42. Then, the mobile terminal 1 and the new connection-destination base station 2E use the next-generation wireless communication units 21 and 41 to transmit and receive user data to and from each other. Next-generation PHS connection sequence is performed using

  Then, as shown in FIG. 25, the mobile terminal 1 uses the next-generation radio communication unit 21 to transmit the base station specifying information for specifying the mobile terminal 1 and the base station specifying information for specifying the base station 2A to the base station. Send to 2E.

  Thereafter, the base station 2E transmits network connection information to the network 4. Thereby, the initial setting of the communication connection between the portable terminal 1 and the network 4 via the base station 2E is performed. Thereafter, the same processing as in step s43 is executed, whereby the base station 2A and the base station 2E transmit the same user data to the mobile terminal 1. FIG. 26 is a diagram schematically showing the state of communication connection at this time. Thereafter, as shown in FIG. 27, the communication between the current method wireless communication unit 22 of the mobile terminal 1 and the current method wireless communication unit 42 of the base station 2A is disconnected.

  According to the communication system as described above, while the communication terminal 1 is performing an operation of specifying the new connection destination base station 2E, and the mobile terminal 1 and the new connection destination base station 2E receive user data. Even during the initial setting for enabling transmission / reception, the mobile terminal 1 and the initially connected base station 2E transmit / receive user data to / from each other by the current PHS. Therefore, the time during which the mobile terminal 1 and the base station 2 cannot transmit / receive user data to each other can be shortened.

  Note that the communication terminal 1 according to the first and second embodiments described above performs wireless communication with the base station 1 using signals in two radio frequency bands (next-generation PHS and current PHS signals) that do not overlap each other. However, radio communication with the base station 1 may be performed using signals of three or more radio frequency bands that do not overlap each other. That is, the communication terminal 1 may be provided with three or more wireless communication units that perform wireless communication with the base station 1 using signals of three or more wireless frequency bands that do not overlap each other. Even in this case, when performing a handover, the communication terminal 1 communicates with the base station 2 using one radio communication unit among a plurality of radio communication units, and communicates with another radio communication unit. Is used to initialize the communication connection with the new connection destination base station 2, and then communicates with the new connection destination base station 2 using the other wireless communication unit or the one wireless communication unit. By performing the above, the same effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Mobile terminal 2, 2A, 2B, 2C, 2D, 2E Base station 4 Network 14 Next-generation system detection part 18 Current system detection part 21, 41 Next-generation system radio communication part 22, 42 Current system radio communication part 25, 45 Control Part

Claims (12)

A plurality of radio communication units that communicate with a base station using signals of a plurality of radio frequency bands that do not overlap each other;
Communication quality between a first radio communication unit that communicates with a base station using a signal in a first radio frequency band among the plurality of radio communication units, and a base station with which the first radio communication unit is communicating A first detector for detecting
Among the plurality of wireless communication units, the second wireless communication unit communicates with a second wireless communication unit that communicates with a base station using a signal in a second wireless frequency band other than the first wireless frequency band. A second detector for detecting communication quality with the base station;
When it is determined that the communication quality detected by the first detection unit does not satisfy a standard, the second radio communication unit and a plurality of bases are maintained in a state where communication between the first radio communication unit and the base station is maintained. A base station specifying means for specifying a new connection destination base station based on the communication quality with the station;
In a state where communication between the first wireless communication unit and the base station is maintained, a first setting for establishing a communication connection between the second wireless communication unit and the new connection destination base station, A first connection establishing means for performing communication with the new connection destination base station in the second wireless communication unit;
Communication connection between the first wireless communication unit and the new connection destination base station in a state in which communication between the first wireless communication unit and the base station is maintained after the first setting is performed. A second connection establishing means for performing a second setting for establishing the communication by causing the second wireless communication unit to communicate with the base station of the new connection destination;
First communication control for disconnecting communication between the first wireless communication unit and the base station and causing the first wireless communication unit to communicate with the new connection destination base station after the second setting is performed. And a communication terminal. The communication terminal according to claim 1,
After the first setting is made, is the second wireless communication unit capable of communication connection between the new connection destination base station and the first wireless communication unit from the new connection destination base station? Receiving communication availability information indicating whether or not
When the communication availability information indicates that communication connection between the new connection destination base station and the first wireless communication unit is possible, the second setting is performed and the first communication control is performed. Means disconnects communication between the first wireless communication unit and the base station, and causes the first wireless communication unit to communicate with the new connection destination base station;
When the communication availability information indicates that communication connection between the new connection destination base station and the first wireless communication unit is not possible, the first wireless communication is performed after the first setting is performed. A communication terminal further comprising: a second communication control unit that disconnects communication between the communication unit and the base station, and causes the second wireless communication unit to communicate with the new connection destination base station. A plurality of radio communication units that communicate with a base station using signals of a plurality of radio frequency bands that do not overlap each other;
Communication quality between a first radio communication unit that communicates with a base station using a signal in a first radio frequency band among the plurality of radio communication units, and a base station with which the first radio communication unit is communicating A first detector for detecting
Among the plurality of wireless communication units, the second wireless communication unit communicates with a second wireless communication unit that communicates with a base station using a signal in a second wireless frequency band other than the first wireless frequency band. A second detector for detecting communication quality with the base station;
Communication quality between a base station capable of communicating using signals in the first and second radio frequency bands detected by the first detection unit and the first radio communication unit communicating with the base station is a reference. Is determined based on the communication quality between the second radio communication unit and the plurality of base stations in a state in which communication between the first radio communication unit and the base station is maintained. A base station specifying means for specifying a connection destination base station;
A setting for establishing a communication connection between the second wireless communication unit and the new connection destination base station in a state where communication between the first wireless communication unit and the base station is maintained. 2 connection establishing means for making the wireless communication unit communicate with the new connection destination base station;
Communication control means for disconnecting communication between the first wireless communication unit and the base station after the setting is performed and causing the second wireless communication unit to communicate with the new base station of the connection destination. , Communication terminal. A communication terminal according to any one of claims 1 to 3,
The first wireless communication unit and the second wireless communication unit are communication terminals that communicate with a base station according to different communication standards. A base station that communicates with the communication terminal according to claim 1,
A plurality of base station side radio communication units that communicate with the communication terminal using signals of a plurality of radio frequency bands that do not overlap each other;
A base station side control unit for controlling the plurality of base station side radio communication units,
The plurality of base station side wireless communication units,
A first base station-side radio communication unit that communicates with the communication terminal using a signal in the first radio frequency band;
A second base station side radio communication unit that communicates with the communication terminal using a signal of the second radio frequency band,
When the base station is specified as the new connection destination base station by the base station specifying means of the communication terminal,
The base station side control unit
When the communication terminal performs the first setting, a setting for establishing a communication connection between the second base station side wireless communication unit and the second wireless communication unit of the communication terminal is set to the second setting. By making the base station side radio communication unit communicate with the second radio communication unit of the communication terminal,
When the communication terminal performs the second setting, a setting for establishing a communication connection between the first base station side wireless communication unit and the first wireless communication unit of the communication terminal is set to the second setting. By making the base station side radio communication unit communicate with the second radio communication unit of the communication terminal,
When the first communication control unit of the communication terminal disconnects the communication between the first wireless communication unit and the base station and causes the first wireless communication unit to communicate with the new connection destination base station. A base station that causes the first base station-side radio communication unit to communicate with the first radio communication unit of the communication terminal. A base station that communicates with the communication terminal according to claim 2,
A plurality of base station side radio communication units that communicate with the communication terminal using signals of a plurality of radio frequency bands that do not overlap each other;
A base station side control unit for controlling the plurality of base station side radio communication units,
The plurality of base station side wireless communication units,
A first base station-side radio communication unit that communicates with the communication terminal using a signal in the first radio frequency band;
A second base station side radio communication unit that communicates with the communication terminal using a signal of the second radio frequency band,
When the base station is specified as the new connection destination base station by the base station specifying means of the communication terminal,
The base station side control unit
When the communication terminal performs the first setting, a setting for establishing a communication connection between the second base station side wireless communication unit and the second wireless communication unit of the communication terminal is set to the second setting. By making the base station side radio communication unit communicate with the second radio communication unit of the communication terminal,
When the communication terminal performs the second setting, a setting for establishing a communication connection between the first base station side wireless communication unit and the first wireless communication unit of the communication terminal is set to the second setting. By making the base station side radio communication unit communicate with the second radio communication unit of the communication terminal,
When the first communication control unit of the communication terminal disconnects the communication between the first wireless communication unit and the base station and causes the first wireless communication unit to communicate with the new connection destination base station. In order for the first base station side radio communication unit to communicate with the first radio communication unit of the communication terminal,
The base station side control unit
The second base station side wireless communication unit transmits the communication availability information to the second wireless communication unit of the communication terminal,
The base station side control unit
When the second communication control means of the communication terminal disconnects the communication between the first wireless communication unit and the base station, and causes the second wireless communication unit to communicate with the new connection destination base station. Is a base station that causes the second base station side radio communication unit to communicate with the second radio communication unit of the communication terminal. A communication terminal and a plurality of base stations;
The communication terminal is
A plurality of radio communication units that communicate with a base station using signals of a plurality of radio frequency bands that do not overlap each other;
Communication quality between a first radio communication unit that communicates with a base station using a signal in a first radio frequency band among the plurality of radio communication units, and a base station with which the first radio communication unit is communicating A first detector for detecting
Among the plurality of wireless communication units, the second wireless communication unit communicates with a second wireless communication unit that communicates with a base station using a signal in a second wireless frequency band other than the first wireless frequency band. A second detector for detecting communication quality with the base station;
When it is determined that the communication quality detected by the first detection unit does not satisfy a standard, the second wireless communication unit and the plurality of the plurality of wireless communication units are maintained in a state in which communication between the first wireless communication unit and the base station is maintained. A base station specifying means for specifying a new connection destination base station based on communication quality with the base station;
In a state where communication between the first wireless communication unit and the base station is maintained, a first setting for establishing a communication connection between the second wireless communication unit and the new connection destination base station, A first connection establishing means for performing communication with the new connection destination base station in the second wireless communication unit;
Communication connection between the first wireless communication unit and the new connection destination base station in a state in which communication between the first wireless communication unit and the base station is maintained after the first setting is performed. A second connection establishing means for performing a second setting for establishing the communication by causing the second wireless communication unit to communicate with the base station of the new connection destination;
Communication control means for disconnecting communication between the first radio communication unit and the base station after the second setting has been performed, and causing the first radio communication unit to communicate with the new base station of the connection destination; A communication system comprising: A communication system according to claim 7,
After the communication terminal has identified the new connection destination base station by the base station identification means, the communication control means disconnects communication between the first wireless communication unit and the base station, and Before performing communication with the new connection destination base station in one wireless communication unit, communication is performed between the network to which the plurality of base stations are connected and the connection destination base station, and A communication system that performs settings for establishing a communication connection between the communication terminal and the network by communicating between the base station of the connection destination and the communication terminal. A communication system according to claim 8,
After the communication terminal performs the second setting, the communication control means disconnects communication between the first wireless communication unit and the base station, and the new connection to the first wireless communication unit Before communicating with the previous base station, the network transmits the same user data to the base station with which the first wireless communication unit is communicating and the connected base station,
The base station with which the first wireless communication unit is communicating transmits user data from the network to the first wireless communication unit of the communication terminal,
The connection destination base station transmits user data from the network to the second wireless communication unit of the communication terminal. A communication terminal and a plurality of base stations;
The communication terminal is
A plurality of radio communication units that communicate with a base station using signals of a plurality of radio frequency bands that do not overlap each other;
Communication quality between a first radio communication unit that communicates with a base station using a signal in a first radio frequency band among the plurality of radio communication units, and a base station with which the first radio communication unit is communicating A first detector for detecting
Among the plurality of radio communication units, a second radio communication unit that communicates with a base station using a signal in a second radio frequency band other than the first radio frequency band and a base in which the second radio communication unit communicates A second detection unit for detecting communication quality with the station;
Communication quality between a base station capable of communicating using signals in the first and second radio frequency bands detected by the first detection unit and the first radio communication unit communicating with the base station is When it is determined that the standard is not satisfied, the communication between the first wireless communication unit and the base station is maintained and a new communication is performed based on the communication quality between the second wireless communication unit and the plurality of base stations. A base station identification means for identifying a base station to be connected to,
A setting for establishing a communication connection between the second wireless communication unit and the new connection destination base station in a state where communication between the first wireless communication unit and the base station is maintained. 2 connection establishing means for making the wireless communication unit communicate with the new connection destination base station;
Communication control means for disconnecting communication between the first wireless communication unit and the base station after the setting is performed and causing the second wireless communication unit to communicate with the new base station of the connection destination. ,Communications system. The communication system according to claim 10, wherein
After the communication terminal has identified the new connection destination base station by the base station identification means, the communication control means disconnects communication between the first wireless communication unit and the base station, and 2 before making the wireless communication unit communicate with the new connection destination base station, communicating between the network to which the plurality of base stations are connected and the connection destination base station, and A communication system that performs settings for establishing a communication connection between the communication terminal and the network by communicating between the base station of the connection destination and the communication terminal. The communication system according to claim 11, wherein
Before the communication terminal causes the communication control means to disconnect the communication between the first wireless communication unit and the base station and cause the second wireless communication unit to communicate with the new connection destination base station. The network transmits the same user data to the base station with which the first wireless communication unit is communicating and the base station to which the connection is made,
The base station with which the first wireless communication unit is communicating transmits user data from the network to the first wireless communication unit of the communication terminal,
The connection destination base station transmits user data from the network to the second wireless communication unit of the communication terminal.

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