JP2013236336A - Mobile terminal, communication system, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile terminal, a communication system, and a communication method that can further reliably prevent quality deterioration in a communication service.SOLUTION: A mobile station 1 comprises: a service type determination unit 14 for determining whether or not it is a communication situation that a voice service is being provided when the mobile station 1 is in a cell subordinate to a first base station; and a terminal transmission unit 16 for performing processing to hand over to a second base station if it has been determined that it is the above-mentioned communication situation. This makes processing to hand over to the second base station performed if it has been determined it is the above-mentioned communication situation during provision of the voice service at timing T3 before timing T1 when handover processing H in Figure 5 is performed. Hereby, this makes it possible to perform handover before radio quality becomes bad at which communication instantaneous disconnection, which has a big impact during provision of the voice service, can happen, and quality deterioration in the communication service can be further reliably prevented.

Description

  The present invention relates to a mobile terminal capable of wireless communication with a plurality of base stations, a communication system including a plurality of base stations and mobile terminals, a communication method performed by the mobile terminal, and a communication method performed by the communication system.

  Conventionally, a mobile station capable of selecting an optimum base station as a handover destination has been proposed. For example, Patent Document 1 discloses a mobile station that acquires measurement information indicating uplink and downlink communication quality with a base station, and is optimal for each uplink and downlink based on this measurement information. A mobile station that determines a base station, determines a priority link among uplink and downlink according to the type of information service to be used, and selects a base station determined to be optimal for the priority link as a handover destination. It is disclosed.

Republished patent WO2009 / 044458

  If the service being provided to the user in the mobile station that performs the handover as described above is a data service (for example, a data communication service based on LTE: Long Term Evolution), even if a communication interruption occurs, the service is provided. The impact of is relatively small. However, if the service being provided to the user at the time of handover is a voice service (for example, Volte: a voice call service using Voice-Over-LTE), a communication interruption may occur. If this occurs, the voice is interrupted due to packet loss, so the impact on this service is relatively large.

  More specifically, as shown in FIG. 1, a conventional mobile station M residing in an LTE broadband area Ab (eg, 10 MHz wide) is moving to an LTE narrowband area An (eg, 5 MHz wide). Suppose there is. Here, the radio quality Qn in the LTE narrowband area An is improved toward the inside of the LTE narrowband area An, but the radio quality Qb in the LTE wideband area Ab is directed to the outside (area end) of the LTE wideband area Ab. Decrease according to. The mobile station M, which has obtained a relatively high communication speed in the LTE broadband area Ab, is set to stay in the LTE broadband area Ab for as long as possible. Normally, the handover process H is performed at the timing T1. Is called.

  However, since the radio quality Qb at the timing T2 that is a relatively short time before the timing T1 at which the handover process H is performed is also as low as the radio quality Qb at the timing T1, an instantaneous communication interruption occurs. Cheap. Here, when communication is interrupted when the service being provided is a voice service, the voice is interrupted, and the influence on the service is relatively large. As a result, the quality of the communication service may be deteriorated.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a mobile terminal, a communication system, and a communication method that can more reliably prevent deterioration in quality of communication services. And

  A mobile terminal according to an aspect of the present invention is a mobile terminal capable of wireless communication with a plurality of base stations, and is a communication in which a voice service is being provided to a cell under the control of the first base station Service determining means for determining whether or not a situation is present, and terminal control means for performing processing for handing over to the second base station when the service determining means determines that the communication status is established. It is characterized by.

  According to the mobile terminal according to an aspect of the present invention, it is determined whether or not a communication status in which a voice service is being provided while being in a cell under the control of the first base station is in this communication status. Is determined, a process for handing over to the second base station is performed. As a result, when it is determined that the above-described communication state in which the voice service is being provided before the timing T1 at which the handover process H in FIG. 1 is performed, a process for performing a handover to the second base station is performed. Is called. As a result, it becomes possible to perform a handover before the wireless quality that can cause an instantaneous interruption of communication having a large influence during provision of the voice service can be achieved, and it is possible to more reliably prevent the deterioration of the quality of the communication service.

  In a mobile terminal according to another aspect, an acquisition unit that acquires first quality information indicating communication quality of wireless communication with the first base station, and a communication quality indicated by the first quality information acquired by the acquisition unit is predetermined. Quality determination means for determining whether or not the quality is satisfied, and the service determination means determines whether or not the communication status is in a case where the quality determination means determines that the predetermined quality is satisfied. Also good.

  In this form, it is determined whether or not the communication quality indicated by the acquired first quality information satisfies the predetermined quality, and when it is determined that the predetermined quality is satisfied, it is determined whether or not the communication status is the above-described state. It becomes possible to do.

  In the mobile terminal according to another aspect, when processing for handover is performed by the terminal control unit, second quality information indicating communication quality of wireless communication with the second base station is acquired, and the second Condition determining means for determining whether or not the communication quality indicated by the quality information satisfies a predetermined condition, and the second quality information acquired by the condition determining means when the condition determining means determines that the predetermined condition is satisfied Quality transmitting means for transmitting to the first base station may be further provided.

  In this embodiment, when processing for handover is performed, it is determined whether or not the communication quality indicated by the acquired second quality information satisfies a predetermined condition, and when it is determined that the predetermined condition is satisfied The acquired second quality information can be transmitted to the first base station.

  A communication system according to an aspect of the present invention is a communication system including first and second base stations and a mobile terminal capable of wireless communication with each of the first and second base stations, The mobile terminal has information transmission means for transmitting service information indicating a service being provided to the first base station, and the first base station is providing a voice service based on the service information transmitted by the information transmission means. And a base station that performs processing for handing over the mobile terminal to the second base station when it is determined that the communication state is determined by the state determination unit. And a control means.

  According to the communication system according to an aspect of the present invention, it is determined whether or not the mobile terminal is in a communication state in which a voice service is being provided. Processing for handing over to the station is performed. As a result, when it is determined that the above-described communication state in which the voice service is being provided before the timing T1 at which the handover process H in FIG. 1 is performed, a process for performing a handover to the second base station is performed. Is called. As a result, it becomes possible to perform a handover before the wireless quality that can cause an instantaneous interruption of communication having a large influence during provision of the voice service can be achieved, and it is possible to more reliably prevent the deterioration of the quality of the communication service.

  A communication method according to an aspect of the present invention is a communication method performed by a mobile terminal capable of wireless communication with a plurality of base stations, and provides a voice service while being in a cell under the control of the first base station. A service determination step in which the mobile terminal determines whether or not the communication status is in the middle, and if the service determination step determines that the mobile terminal is in a communication status, the mobile terminal performs processing for handing over to the second base station And a terminal control step.

  According to the communication method according to an aspect of the present invention, it is determined whether or not the communication status in which voice service is being provided while being in the cell under the control of the first base station, and the communication status is in this communication status. Is determined, a process for handing over to the second base station is performed. As a result, when it is determined that the above-described communication state in which the voice service is being provided before the timing T1 at which the handover process H in FIG. 1 is performed, a process for performing a handover to the second base station is performed. Is called. As a result, it becomes possible to perform a handover before the wireless quality that can cause an instantaneous interruption of communication having a large influence during provision of the voice service can be achieved, and it is possible to more reliably prevent the deterioration of the quality of the communication service.

  A communication method according to an aspect of the present invention is a communication method performed by a communication system including first and second base stations and a mobile terminal capable of wireless communication with each of the first and second base stations. An information transmission step in which the mobile terminal transmits service information indicating a service being provided to the first base station, and a voice service is provided by the service information transmitted in the information transmission step by the first base station. A status determination step for determining whether or not the communication status is being provided, and a process for handing over the mobile terminal to the second base station when it is determined that the communication status is determined by the status determination step And a base station control step.

  According to the communication method of one aspect of the present invention, it is determined whether or not the communication status is providing voice service, and when it is determined that the communication status is present, the handover to the second base station is performed. The process for doing is performed. As a result, when it is determined that the above-described communication state in which the voice service is being provided before the timing T1 at which the handover process H in FIG. 1 is performed, a process for performing a handover to the second base station is performed. Is called. As a result, it becomes possible to perform a handover before the wireless quality that can cause an instantaneous interruption of communication having a large influence during provision of the voice service can be achieved, and it is possible to more reliably prevent the deterioration of the quality of the communication service.

  ADVANTAGE OF THE INVENTION According to this invention, the mobile terminal, communication system, and communication method which can prevent the quality degradation of a communication service more reliably can be provided.

It is timing explanatory drawing explaining the radio quality in the timing at the time of the conventional mobile station performing a handover process, and the timing. It is a functional block diagram for demonstrating the outline of the main function structures of a moving apparatus. It is a physical block diagram for demonstrating the outline of the main physical structures of a moving apparatus. 6 is a flowchart for explaining a flow of a handover process in a mobile device. It is timing explanatory drawing explaining the radio | wireless quality in the timing when the mobile device performs a handover process, and the timing for explaining the effect by a mobile device and a base station. It is a functional block diagram for demonstrating the outline of the main function structures of a mobile device and a base station. It is a physical block diagram for demonstrating the outline of the main physical structures of a base station. It is a flowchart for demonstrating the flow of the hand-over process in a base station.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(1) First Embodiment (1-1) Configuration of Mobile Terminal According to First Embodiment First, with respect to the configuration of a mobile device (mobile terminal) according to the first embodiment of the present invention, FIG. 2 and FIG. It explains using. FIG. 2 is a functional block diagram for explaining the outline of the main functional configuration of the mobile device 1, and FIG. 3 shows the outline of the main physical configuration of the mobile device 1 (and the mobile device 2 described later). FIG. The mobile device 1 is a terminal such as a mobile phone terminal or a smartphone capable of performing handover by changing a cell in the area by performing wireless communication with a plurality of base stations. The mobile device 1 provides a user with a data service (for example, a data communication service based on LTE: Long Term Evolution) and a voice service (for example, a voice call based on Volte: Voice-Over-LTE, which is a voice communication technology using LTE). Service).

  As shown in FIG. 3, the mobile device 1 includes a CPU 101 (Central Processing Unit), a RAM 102 (Random Access Memory), a ROM 103 (Read Only Memory), an operation unit 104, and a wireless communication unit 105 as main physical components. , A portable computer terminal configured by hardware such as the display 106 and the antenna 107. When these components operate, each function of the mobile device 1 is exhibited. As shown in FIG. 2, the mobile device 1 includes an antenna control unit 11, a terminal reception unit 12 (acquisition unit), a radio quality estimation unit 13 (quality determination unit), a service type determination as main functional components. A unit 14 (service determination unit), a report condition determination unit 15 (terminal control unit, condition determination unit), and a terminal transmission unit 16 (quality transmission unit).

  The antenna control unit 11 is a control function part that performs transmission / reception processing and control of signals transmitted and received by the antenna 107 (see FIG. 1). The antenna control unit 11 performs the above management and control while being connected to the antenna 107.

  The terminal receiving unit 12 is an arithmetic processing function part that performs an analysis process on the signal transmitted and received by the antenna control unit 11. For example, the terminal reception unit 12 obtains the first quality information indicating the communication quality and the notification of the movement control parameter by performing arithmetic processing on the signal received and processed by the antenna control unit 11.

  Here, the first quality information is the communication quality of the wireless communication with the first base station under the cell in which the mobile device 1 is currently located (for example, the downlink of the communication being executed in the mobile device 1). This is information indicating the electric field strength of the radio signal. In addition, the mobility control parameter is a parameter (such as a handover threshold or Time To Trigger) used as a reference when determining whether or not the mobile device 1 is handed over to a second base station adjacent to the first base station. Parameter), which is an initial value having an offset value of communication quality. The movement control parameter includes a first parameter and a second parameter. The first parameter is a reference value parameter to be compared with the electric field strength (communication quality in the mobile device 1) in the cell where the mobile device 1 is located. The second parameter is a comparison target of the difference between the electric field strength (own cell strength) in the cell where the mobile device 1 is located (own cell) and the electric field strength (adjacent cell strength) in the adjacent cell (cell adjacent to the own cell). Is a reference value parameter.

  The terminal receiving unit 12 can also obtain an instruction signal instructing execution of processing up to the completion of the handover by analyzing the signal received and processed by the antenna control unit 11.

  The radio quality estimation unit 13 is an arithmetic processing function unit that determines whether or not the communication quality indicated by the first quality information acquired by the terminal reception unit 12 satisfies the parameter condition (predetermined quality). For example, a state in which the electric field strength (communication quality indicated by the first quality information) of the downlink radio signal of the communication being executed in the mobile device 1 is less than (or less than) a predetermined strength (first threshold) continues for a certain time or more. In this case, it is determined that the parameter condition is satisfied. In addition, for example, a state in which the electric field strength of the downlink radio signal of the communication being executed in the mobile device 1 is not more than (or less than) the reference value of the electric field strength indicated by the first parameter described above continues for a certain time or longer. In the case of good quality, it may be determined that the parameter condition is satisfied.

  The service type determination unit 14 is an arithmetic processing function part that determines whether or not a communication state in which the above voice service is being provided while being in the above cell. For example, in a situation where a voice service is provided, the user can make a call using the mobile device 1.

  The reporting condition determination unit 15 performs a preparation process for handing over to the second base station adjacent to the first base station when the service type determination unit 14 determines that the communication status is in the above-described communication state. Part. The preparation process for handing over to the second base station is a process of changing both the first parameter and the second parameter included in the mobility control parameter from the initial value to the changed value, for example. The initial values of the first parameter and the second parameter are, for example, a3-offset value and hysteresis value of 1.5 dB, respectively, and the changed values are, for example, a3-offset value and hysteresis value of 0 dB, respectively. After the change of the first parameter, the radio quality estimation unit 13 determines whether or not the communication quality indicated by the first quality information acquired by the terminal reception unit 12 satisfies the parameter condition (predetermined quality).

  In addition, the reporting condition determination unit 15 performs a preparation process for handing over to the second base station, and then determines that the above-described parameter condition is satisfied by the radio quality estimation unit 13, Second quality information indicating the communication quality of wireless communication with the base station is acquired, and it is determined whether or not the communication quality indicated by the second quality information satisfies a report condition (predetermined condition) described later. For example, the electric field strength of the downlink radio signal of the communication being executed in the mobile device 1 after the handover preparation process (change from the initial value of the mobility control parameter) (own cell strength which is the communication quality indicated by the second quality information) is It is determined that the reporting condition is satisfied when the quality is such that the state of being less than (or less than) the predetermined cell strength (second threshold) than the adjacent cell strength continues for a certain period of time. The predetermined intensity may be a difference value such as several dB indicated by the second parameter described above.

  When the report condition determining unit 15 determines that the report condition is satisfied, the terminal transmitting unit 16 transmits the second quality information acquired by the report condition determining unit 15 to the first base station.

(1-2) Flow of Handover Processing in Mobile Station Next, the flow of handover processing (communication method) in the mobile station 1 will be described with reference to FIG. FIG. 4 is a flowchart for explaining the flow of the handover process in the mobile device 1.

  The process shown in the flowchart of FIG. 4 is repeatedly executed at a predetermined timing from when the mobile device 1 is turned on until it is turned off.

  First, the service type determination unit 14 determines whether or not the above-described voice service is being provided while being in the cell (that is, the service type being provided is a voice service) (step S01, Service determination step). When it is determined that the above-described voice service is being provided (that is, the service type being provided is a voice service), the process proceeds to step S02 described later. On the other hand, if it is determined that the above voice service is not being provided, the process proceeds to step S03 described below.

  In step S02, the reporting condition determination unit 15 changes the mobility control parameter from the initial value (terminal control step). As a result, the mobile device 1 reads the movement control parameter. And it transfers to below-mentioned step S03.

  In step S03, the radio quality estimation unit 13 determines whether or not the communication quality indicated by the first quality information satisfies the parameter condition (predetermined quality). When it is determined that the parameter condition is satisfied, the report condition determination The unit 15 acquires the second quality information, and determines whether or not the communication quality indicated by the second quality information satisfies the reporting condition. When it is determined that the communication quality indicated by the second quality information satisfies the reporting condition, the process proceeds to step S04 described later. On the other hand, when it is determined that the communication quality indicated by the second quality information does not satisfy the reporting condition, the series of processing ends.

  In step S04, the terminal transmission unit 16 reports the downlink radio quality by transmitting the second quality information acquired by the report condition determination unit 15 to the first base station. And it transfers to below-mentioned step S05.

  In step S05, the terminal reception unit 12 analyzes the signal received and processed by the antenna control unit 11, thereby obtaining an instruction signal instructing execution of processing up to the completion of the handover. Then, a series of processing ends.

(1-3) Effects of Mobile Station According to the mobile station 1, as shown in FIG. 5, the mobile station 1 is present in the LTE broadband area Ab (the area of the cell under the control of the first base station) (for example, 10 MHz wide). It is determined whether or not the communication status in which a voice service is being provided in the service area. If it is determined that the communication status is present, the LTE narrowband area An (second base station (for example, 5 MHz wide)) is determined. The process H1 for handing over to the cell area under the control (replacement of the movement control parameter in step S04 in FIG. 4) is performed.

  As a result, when it is determined that the voice communication service is being provided at the timing T3 prior to the timing of the handover process H by the conventional mobile station M (timing T1 in FIG. 5), the LTE narrowband A process H1 for handing over to the area An is performed.

  As a result, it is possible to perform handover before the wireless quality (wireless quality Qb at the timing T2 in FIG. 1) (timing T3 in FIG. 5) that can cause an instantaneous interruption of communication that has a great influence during the provision of the voice service. Thus, it is possible to more reliably prevent the quality deterioration of the communication service (voice service) caused by the packet loss due to the instantaneous interruption of communication.

  Also, according to the mobile device 1, it is determined whether or not the communication quality indicated by the acquired first quality information satisfies the parameter condition (step S02 in FIG. 4), and when it is determined that the parameter condition is satisfied. Then, it is possible to determine whether or not the communication status is as described above (step S03 in FIG. 4).

(2) Second Embodiment (2-1) Configuration of Communication System Including Mobile Terminal According to Second Embodiment Subsequently, with respect to the configuration of the communication system including the mobile device (mobile terminal) according to the second embodiment, FIG. This will be described with reference to FIGS. FIG. 6 is a functional block diagram for explaining an outline of main functional configurations of the mobile device 2 and the first base station 3 (and the second base station 4), and FIG. 2 is a physical configuration diagram for explaining an outline of a main physical configuration of a station 3. FIG.

  Here, the mobile device 2 is a terminal such as a mobile phone terminal or a smartphone that can perform handover by changing the cell in the area by performing wireless communication with a plurality of base stations. In addition, the communication system 10 wirelessly communicates between the first base station 3 and the second base station 4 that are subordinate to the cells adjacent to each other, and the first base station 3 and the second base station 4 respectively. This is a system including a mobile device 2 capable of communication. The mobile device 2 provides the user with a data service (for example, LTE: data communication service based on Long Term Evolution) and a voice service (for example, Volte: Voice-Over-LTE, which is a voice call technology using LTE). Voice call service).

  As shown in FIG. 3, the mobile device 2 includes a CPU 101 (Central Processing Unit), a RAM 102 (Random Access Memory), a ROM 103 (Read Only Memory), an operation unit 104, and a wireless communication unit 105 as main physical components. , A portable computer terminal configured by hardware such as the display 106 and the antenna 107. By operating these components, each function of the mobile device 2 is exhibited.

  As shown in FIG. 6, the mobile device 2 includes, as main functional components, an antenna control unit 21, a terminal reception unit 22 (acquisition unit), a radio quality estimation unit 23 (quality determination unit), a report condition determination A unit 24 (condition determination unit), a service type determination unit 25 (service determination unit), and a terminal transmission unit 26 (information transmission unit) are configured.

  The antenna control unit 21 is a control function part that performs transmission and reception processing and control of signals transmitted and received by the antenna 107 (see FIG. 1). The antenna control unit 21 performs the above management and control while being connected to the antenna 107.

  The terminal receiving unit 22 is an arithmetic processing function part that performs an analysis process on a signal that is transmitted and received by the antenna control unit 21. For example, the terminal reception unit 22 performs arithmetic processing on a signal received and processed by the antenna control unit 21, thereby acquiring first quality information indicating communication quality and a notification of a movement control parameter.

  Here, the first quality information is the communication quality of the wireless communication with the first base station 3 under the cell in which the mobile device 2 is currently located (for example, the communication being executed in the mobile device 2). This is information indicating the electric field strength of the downlink radio signal. Further, the mobility control parameter is a parameter (a parameter such as a handover threshold or Time To Trigger) used as a reference when determining whether or not the mobile device 2 is handed over to the second base station 4, and the communication quality It becomes an initial value having an offset value.

  In addition, the terminal reception unit 22 can acquire an instruction signal instructing execution of processing up to the completion of handover by analyzing a signal received and processed by the antenna control unit 21.

  The wireless quality estimation unit 23 is an arithmetic processing function part that determines whether or not the communication quality indicated by the first quality information acquired by the terminal reception unit 22 satisfies the parameter condition (predetermined quality). For example, when the communication quality indicated by the first quality information is such that the electric field strength of the downlink radio signal of the communication being executed in the mobile device 2 is less than (or less than) a predetermined strength, the parameter condition is It is determined that it is satisfied.

  The reporting condition determination unit 24 indicates the second quality indicating the communication quality of the wireless communication with the second base station when the wireless quality estimation unit 23 determines that the communication quality indicated by the first quality information satisfies the parameter condition. This is an arithmetic processing function part that acquires information and determines whether or not the communication quality indicated by the second quality information satisfies a reporting condition (predetermined condition). For example, the communication quality indicated by the second quality information indicates that the field strength of the downlink radio signal of the communication being executed in the mobile device 2 after the handover preparation process (change from the initial value of the mobility control parameter) is less than or equal to a predetermined strength (or less). ), The reporting condition is determined to be satisfied when the quality is such that the state of) continues for a certain time or more.

  The service type determination unit 25 is an arithmetic processing function part that determines whether or not a communication status in which the above voice service is being provided while being in the above cell. For example, in a situation where a voice service is provided, the user can make a call using the mobile device 2.

  The terminal transmission unit 26 is a communication control unit that transmits service information related to the type of service being provided, which is a determination result by the service type determination unit 25, to the first base station 3. Further, the terminal transmission unit 26 can receive notification of the changed mobility control parameter from the first base station 3 and perform processing for handing over to the second base station 4. The process for handing over to the second base station 4 is, for example, a process of changing the mobility control parameter from the initial value to the notified changed parameter. For example, the a3-offset value and the hysteresis value are each 1.5 dB for the initial value, and the changed value is, for example, the a3-offset value and the hysteresis value are each 0 dB.

  Furthermore, the terminal transmission unit 26 transmits the second quality information acquired by the report condition determination unit 24 to the first base station 3 when the report condition determination unit 24 determines that the report condition is satisfied.

  As shown in FIG. 7, each of the first base station 3 and the second base station 4 includes a CPU 301 (Central Processing Unit), a RAM 302 (Random Access Memory), and a ROM 303 (Read Only Memory), a communication module 304, and a portable computer terminal configured by hardware such as the auxiliary storage device 305. When these components operate, the functions of the first base station 3 and the second base station 4 are exhibited.

  As shown in FIG. 6, each of the first base station 3 and the second base station 4 includes an antenna control unit 31, a base station reception unit 32 (acquisition means), a service, as main functional components. A type determination unit 33 (situation determination unit), a parameter notification unit 34 (base station control unit), and a base station transmission unit 35 (base station control unit) are configured.

  The antenna control unit 31 is a control function part that performs transmission / reception processing and control of signals transmitted and received by the base station antenna.

  The base station receiving unit 32 is an arithmetic processing function part that performs an analysis process on the signal transmitted and received by the antenna control unit 31. For example, the base station reception unit 32 analyzes the signal received and processed by the antenna control unit 31 to acquire service information related to the type of service being provided by the mobile device 2 from the mobile device 2. Further, the base station receiving unit 32 can also acquire the second quality information acquired by the reporting condition determining unit 24 from the mobile device 2.

  The service type determination unit 33 is an arithmetic processing function unit that determines whether the mobile device 2 is in a communication state in which a voice service is being provided using the service information transmitted from the terminal transmission unit 26. For example, in a situation where a voice service is provided, the user can make a call using the mobile device 2.

  The parameter notification unit 34 is a control function unit that performs processing for handing over the mobile device 2 to the second base station 4 when the service type determination unit 33 determines that the communication status is in the above-described state. The process for handing over to the second base station 4 is, for example, a process for transmitting to the mobile device 2 the mobility control parameter changed from the initial value. The mobility control parameter is a parameter used as a reference when the mobile device 2 determines whether or not to hand over to the second base station 4, and is an initial value having an offset value of communication quality.

  The base station transmission unit 35 is a communication control part that transmits the mobile control parameter changed from the initial value to the mobile device 2. Further, the base station transmission unit 35 can transmit to the mobile device 2 an instruction signal instructing execution of processing up to the completion of the handover after the changed mobility control parameter is transmitted to the mobile device 2.

(2-2) Flow of Handover Processing in First Base Station Subsequently, the flow of handover processing (communication method) in the first base station 3 included in the communication system 10 will be described with reference to FIG. FIG. 8 is a flowchart for explaining the flow of the handover process in the first base station 3. The process shown in the flowchart of FIG. 8 is repeatedly executed at a predetermined timing from when the first base station 3 is activated until it is shut down.

  First, the terminal transmission unit 26 of the mobile device 2 transmits a report of service information related to the type of service being provided by the mobile device 2, and the base station reception unit 32 relates to the type of service being provided by the mobile device 2. A report of service information is received from the mobile device 2 (step S11, information transmission step).

  Next, the service type determination unit 33 uses the service information transmitted by the terminal transmission unit 26 in a communication situation in which a voice service is being provided in the mobile device 2 (that is, the service type being provided is a voice service). It is determined whether or not there is (step S12, situation determination step). When it is determined that the above-described voice service is being provided (that is, the service type being provided is a voice service), the process proceeds to step S13 described later. On the other hand, if it is determined that the above voice service is not being provided, the process proceeds to step S15 described later.

  In step S13, the parameter notification unit 34 changes the mobility control parameter from the initial value (base station control step). And it transfers to below-mentioned step S14.

  In step S <b> 14, the base station transmission unit 35 transmits to the mobile device 2 and notifies the mobile device 2 of the mobile control parameter changed from the initial value. As a result, the movement control parameter is reread in the mobile device 2. And it transfers to below-mentioned step S15.

  In step S15, the radio quality estimation unit 23 of the mobile device 2 determines whether or not the communication quality indicated by the first quality information (obtained by the terminal reception unit 22) satisfies the parameter condition (predetermined quality). When it is determined that the condition is satisfied, the reporting condition determination unit 24 acquires the second quality information, and when the communication quality indicated by the second quality information satisfies the reporting condition, the terminal transmission unit 26 The second quality information is transmitted to the first base station 3, and the base station receiving unit 32 receives the second quality information for reporting the communication quality from the mobile device 2. Then, the base station transmission unit 35 transmits to the mobile device 2 an instruction signal instructing execution of processing until completion of the handover to the second base station 4 (step S16). Then, a series of processing ends.

(2-3) Outline of Action and Effect by Base Station According to the first base station 3, as shown in FIG. 5, the LTE broadband area Ab (cells under the control of the first base station) (for example, 10 MHz wide) In the communication area in which the mobile device 2 is present and the voice service is being provided, and if it is determined that the communication condition is present, the LTE narrowness (for example, 5 MHz wide) is determined. Processing H1 for handing over the mobile device 2 to the band area An (the area of the cell under the control of the second base station) (replacement of the mobility control parameter in step S14 in FIG. 8) is performed.

  Accordingly, when it is determined that the mobile station 2 is in the above-described communication state in which the voice service is being provided at the timing T3 before the timing of the handover process H by the conventional mobile station M (timing T1 in FIG. 5). Then, a process H1 for handing over the mobile device 2 to the LTE narrowband area An is performed.

  As a result, the mobile device 2 is handed over before the wireless quality (wireless quality Qb at the timing T2 in FIG. 1) is reached (timing T3 in FIG. 5) that may cause an instantaneous interruption of communication that has a great influence while providing the voice service. Therefore, it is possible to more reliably prevent the deterioration of the quality of the communication service (voice service) caused by the packet loss due to the instantaneous interruption of communication.

(3) Modification In the first embodiment described above, the configuration in which the electric field strength of the downlink radio signal of the communication being executed in the mobile device 1 is adopted as the communication quality of the radio communication. However, the present invention is not limited to this. For example, the degree of instability of the electric field strength of the downlink radio signal of the communication being executed in the mobile device 1 may be adopted as the communication quality of the radio communication.

  ADVANTAGE OF THE INVENTION According to this invention, the mobile terminal, communication system, and communication method which can prevent the quality degradation of a communication service more reliably can be provided.

  DESCRIPTION OF SYMBOLS 1, 2 ... Mobile station, 3, 4 ... Base station, 10 ... Communication system 11, 21, 31 ... Antenna control part, 12, 22 ... Terminal receiving part, 13, 23 ... Radio quality estimation part, 14, 25, 33 ... Service type determination unit, 15, 24 ... Report condition determination unit, 16, 26 ... Terminal transmission unit, 32 ... Base station reception unit, 34 ... Parameter notification unit, 35 ... Base station transmission unit, Ab ... Broadband area, An ... narrow band area, H, H1 ... handover process, M ... mobile station, Qb, Qn ... radio quality, T1 to T3 ... timing.

Claims (6)

A mobile terminal capable of wireless communication with a plurality of base stations,
Service determination means for determining whether or not a communication status in which voice service is being provided while being in a cell under the control of the first base station;
A terminal control means for performing a process for handing over to a second base station when the service determination means determines that the communication status is established;
A mobile terminal comprising: Obtaining means for obtaining first quality information indicating communication quality of wireless communication with the first base station;
Quality determination means for determining whether or not the communication quality indicated by the first quality information acquired by the acquisition means satisfies a predetermined quality;
2. The mobile terminal according to claim 1, further comprising: the service determination unit that determines whether or not the communication state is established when the quality determination unit determines that the predetermined quality is satisfied. When the processing for handover is performed by the terminal control means, second quality information indicating communication quality of wireless communication with the second base station is acquired, and communication quality indicated by the second quality information A condition determining means for determining whether or not satisfies a predetermined condition;
A quality transmission means for transmitting the second quality information acquired by the condition determination means to the first base station when the condition determination means determines that the predetermined condition is satisfied;
The mobile terminal according to claim 2, further comprising: A communication system comprising first and second base stations and a mobile terminal capable of wireless communication with each of the first and second base stations,
The mobile terminal
Comprising information transmitting means for transmitting service information indicating a service being provided to the first base station;
The first base station is
Status determination means for determining whether or not a communication status in which a voice service is being provided by the service information transmitted by the information transmission means;
Base station control means for performing processing for handing over the mobile terminal to the second base station when it is determined by the status determination means that the communication status is established;
A communication system comprising: A communication method performed by a mobile terminal capable of wireless communication with a plurality of base stations,
A service determination step in which the mobile terminal determines whether or not the mobile terminal is in a communication state in which a voice service is being provided while being in a cell under the control of the first base station;
A terminal control step in which the mobile terminal performs processing for handing over to a second base station when it is determined by the service determination step that the communication state is established;
A communication method characterized by comprising: A communication method performed by a communication system including first and second base stations and a mobile terminal capable of wireless communication with each of the first and second base stations,
The mobile terminal is
An information transmission step of transmitting service information indicating a service being provided to the first base station;
The first base station is
A situation determination step of determining whether or not a communication situation in which a voice service is being provided by the service information transmitted by the information transmission step;
A base station control step for performing processing for handing over the mobile terminal to the second base station when it is determined by the status determination step that the communication status is established;
A communication method characterized by comprising:

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