JP6212848B2 - Mobile station, communication system, communication method switching method, and communication method switching program - Google Patents

Description

  The present invention relates to a radio system including a base station and a mobile station connected to the base station via a radio channel, and a mobile station, a communication system, a base station, and a communication system switching for switching a communication system among a plurality of communication systems The present invention relates to a method and a program thereof.

  In a communication system that transmits and receives signals between a base station and a mobile station, an analog transmission / reception method has been adopted, but it is being replaced by a digital transmission / reception method.

  The digital transmission / reception system has a high degree of freedom in processing of signals to be transmitted / received, and a large amount of information can be transmitted at high speed by signal processing such as compression, error detection, and error correction, and efficient noise removal is possible. . That is, the voice is easy to recognize by clearing. Moreover, it is possible to give the transmission signal high confidentiality, which is more advantageous than the analog transmission / reception system in terms of security.

  However, if it is attempted to communicate only with the digital transmission / reception method instead of the existing analog transmission / reception method, it is necessary to newly install a base station radio device or a relay device with the digital transmission / reception method, which causes a large cost for the equipment. There is.

  For example, in a fire fighting / emergency wireless communication network, a frequency band of 8 MHz is allocated to a digital communication system in the 260 MHz band for an analog communication system in a 150 MHz band, and the existing analog transmission / reception system fire fighting / emergency radio is shifted. It has been requested. Local governments are being forced to pay for the installation of base stations and relay equipment in order to digitize the fire and emergency wireless communication networks.

  Generally, the frequency band assigned to digital communication is assigned a higher frequency band while avoiding the frequency band occupied by existing analog communication.

  As described above, since the frequency of the carrier wave used in the digital transmission / reception communication is higher than the frequency of the carrier wave in the analog transmission / reception, the communication distance is short, and there is a problem that it is easily affected by the topography and the building. In order to eliminate this influence, it is necessary to add a base station radio device or install a relay device, which increases the cost of equipment.

  On the other hand, the existing analog transmission / reception system has a wide reception range due to signal transmission carried on a relatively long wave carrier wave and is not easily affected by the terrain that interferes with the transmission wave, so the receivable area is relatively wide. There are relatively few areas where reception is impossible.

  Further, in a communication method such as SCPC (Single Carrier Per Channel) used as communication in the digital transmission / reception method, one channel is occupied by one communication. For this reason, when no usable channel is left, even a mobile device having a communication function in the digital transmission / reception system cannot use the communication in the digital transmission / reception system.

  In view of the problems of the digital transmission / reception system as described above, at present, an environment where communication using the analog transmission / reception system can be used is left, and an area where communication using the digital transmission / reception system can be used is superimposed on this communication environment. Yes.

  In such a communication environment, it is desirable for the mobile station to provide redundant communication environments for both the analog transmission / reception system and the digital transmission / reception system. In such a communication environment, the mobile station includes a communication unit using an analog transmission / reception method and a communication unit using a digital transmission / reception method, and has a communication function using both communication methods.

  However, if the mobile station is equipped with communication units of both communication methods, the mobile station becomes larger and power consumption increases.

  In response to this problem, Patent Document 1 discloses a software defined radio that makes it possible to use two communication systems, an analog transmission / reception system and a digital transmission / reception system, by processing using software. In the communication environment as described above, the operation mode is changed according to the communication system in communication and the communication state, and a better communication line is secured.

  In this communication system, the transmission / reception unit is shared between the digital transmission / reception system and the analog transmission / reception system, thereby reducing the size of the apparatus and suppressing power consumption. In addition, this communication system appropriately switches between the analog transmission / reception method and the digital transmission / reception method according to the location and environment of the mobile station in view of the communication quality and the communication state.

  Patent Document 2 discloses a wireless communication system in which a mobile station including an analog receiver and a digital receiver switches operation between the analog receiver and the digital receiver according to the detection state of the base station identification signal.

  Patent Document 3 discloses a software defined radio corresponding to a plurality of wireless communication systems and a plurality of application services. A module group in which modules necessary for each application are set is prepared, and software modules in the storage device are managed by switching the signal processing function by switching the module group unit.

  However, in a wireless device having a switching function between an analog transmission / reception system and a digital transmission / reception system, there is a possibility that a state in which continuous communication cannot be maintained occurs due to this switching operation.

  In the wireless communication device disclosed in Patent Document 1, the control unit 15 determines the change of the operation mode by detecting the asynchronous state of the receiver for a certain period of time. In other words, since a change in transmission / reception method is determined after detecting an asynchronous state for a certain period of time, it is not possible to avoid the occurrence of a state where sufficient signal strength cannot be maintained. For this reason, communication may be interrupted at the time of switching.

  In the wireless communication system disclosed in Patent Document 2, when a pilot signal (a signal identifying a base station) included in a transmission radio wave is detected and the identification signal cannot be detected by the analog receiver, the communication method is changed to analog wireless. Switch from system to digital radio system. When the identification signal cannot be detected by the digital receiver, the communication method is switched from the digital wireless method to the analog wireless method. That is, since the transmission / reception method is switched after waiting for detection of the identification signal, there is a possibility that sufficient signal strength cannot be maintained until it is determined that the detection is impossible.

  In the wireless communication system disclosed in Patent Document 3, if the mobile wireless communication apparatus does not satisfy the desired communication quality due to shadowing or the like, it is determined that the module needs to be incorporated. However, since the communication quality is detected by the electric field measurement function, the signal strength in the transmission / reception method during communication is unavoidable due to the time required for determining the communication quality.

  As described above, if the communication method is changed after detecting a decrease in communication quality, the communication state temporarily decreases. If you try to determine which communication method is good by constantly detecting the communication quality of both the digital transmission / reception method and the analog transmission / reception method, the power required for detection will be reduced. Increase.

  On the other hand, in the train radio system disclosed in Patent Document 4, a radio system corresponding to the radio communication system of each section on the track is automatically selected.

  Patent Document 4 discloses a train radio system that can be switched to a corresponding wireless system by switching software to be implemented. The mobile station mounted on the train traveling on the track determines the radio system selection based on the reception information, the arrangement information, and the direction information.

  That is, in the train radio system disclosed in Patent Document 4, a radio scheme section in which a mobile station device exists is detected based on reception information of a receiving unit and arrangement information indicating an arrangement of radio scheme sections. Further, the section at the current time and the section to move at the next time are determined, and the selection of the radio system at the next time is determined.

JP 2011-223504 A JP 2001-267777 A JP 2006-157935 A JP 2009-164989 A

  In the train radio system disclosed in Patent Document 4, the train which is a mobile station holds the arrangement information about each radio system in the section on the track, and also has the reception information currently received normally. And determine the section on the currently passing track. When communication is no longer possible with the communication method currently being communicated, communication in the communication method of the next section acquired from the array information is started.

  The train, which is a mobile station, switches the communication method while monitoring the reception state of the communication method in the adjacent section on the track. For this reason, it is necessary to perform monitoring processing using another communication method simultaneously with communication processing using the communication method currently in communication. This monitoring process is wasted if a sufficient signal strength is obtained by the communication method currently in communication.

  In addition, the determination of the currently traveling section based on the currently communicating communication method is possible only under the limited condition of traveling the train on the track, that is, moving with one degree of freedom. It is difficult to apply to movement with two degrees of freedom.

  It is difficult to estimate the current position on a plane only by distinguishing between communication using a digital transmission / reception system and communication using an analog transmission / reception system. Further, the information on the transmission / reception method of the adjacent area corresponding to the arrangement information of Patent Document 4 is complicated and enormous because the degree of freedom in the moving direction on the plane is larger than the degree of freedom on the line. Become.

  The present invention has been made in view of the above points, and provides a mobile station, a communication system, a base station, a communication method switching method, and a program thereof capable of continuous communication with stable communication quality on a plane. With the goal.

  In order to achieve the above object, the mobile station of the present invention is a mobile station that communicates with a base station that communicates with a plurality of different communication methods, and obtains position information about the current position of the mobile station. Means for storing communication environment information including distribution information with respect to the current position for communication quality of a plurality of communication schemes and a program, and a base station in one of the plurality of communication schemes controlled by the program A communication means for communicating with the base station, and a control means for selecting a communication method for the communication means to communicate with the base station from a plurality of communication methods based on the communication quality indicated by the distribution information for the position information acquired by the positioning means. It is characterized by having.

  Further, the communication system of the present invention is a communication system including a base station that communicates with a plurality of different communication methods and a mobile station that communicates with the base station, and the mobile station includes location information about the current location. Positioning means for acquiring information, communication environment information including distribution information for the current position for communication quality of a plurality of communication methods, storage means for holding a program, and one communication among the plurality of communication methods controlled by the program The communication means for communicating with the base station by the communication method and the communication method for the communication means to communicate with the base station are selected from a plurality of communication methods based on the communication quality indicated by the distribution information for the position information acquired by the positioning means. And a control means.

  Furthermore, the base station of the present invention is a base station that can communicate with a mobile station using a plurality of different communication schemes, and includes a plurality of communication schemes held by the mobile station and positional information about the current location of the mobile station The mobile station communicates with the mobile station in a communication scheme selected from a plurality of communication schemes based on distribution information on the current position with respect to the communication quality.

  The communication method switching method of the present invention is a communication method switching method for switching the communication method of communication between a base station and a mobile station that communicate with each other by a plurality of different communication methods, and for the current position of the mobile station Obtaining position information of the mobile station, referring to the communication quality for the position information from the communication environment information including distribution information for the current position for the communication quality of a plurality of communication methods, and a plurality of based on the referenced communication quality Selecting a communication method for communication between the base station and the mobile station from the communication methods described above.

  Furthermore, the communication system switching program of the present invention is a communication system switching program for switching the communication system of communication between a base station and a mobile station that communicate with each other by a plurality of different communication systems. Processing for obtaining location information, processing for referring to communication quality for location information from communication environment information including distribution information for the current location for communication quality of multiple communication methods, and processing based on the referenced communication quality And a process of selecting a communication method for communication between a base station and a mobile station from the communication method.

  According to the present invention, the communication range of a mobile device is expanded, and stable communication is possible in an area where only one communication method of a plurality of communication methods is possible or an area where only the other communication method is possible. It is.

An example of the structure of the mobile station which concerns on the 1st Embodiment of this invention is shown. It is a flowchart which shows an example of the procedure of the communication system switching method which concerns on the 1st Embodiment of this invention. An example of the structure of the mobile station which concerns on the 2nd Embodiment of this invention is shown. An example of the structure of the communication system which concerns on the 2nd Embodiment of this invention is shown. It is a flowchart which shows an example of the procedure of the communication system switching method which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows another example of the procedure of the communication system switching method which concerns on the 2nd Embodiment of this invention. An example of the positional information hold | maintained at the mobile station which concerns on the 2nd Embodiment of this invention is shown. An example of the positional information hold | maintained at the mobile station which concerns on the 2nd Embodiment of this invention is shown.

The best mode for carrying out the invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below.
[First Embodiment]
FIG. 1 shows an example of the configuration of a mobile station according to the first embodiment of the present invention.

  The mobile station 101 according to the present embodiment is a mobile station that communicates with a base station that communicates with a plurality of different communication schemes, and includes positioning means 1103, storage means 1105, communication means 1104, control means 1102, and so on. Have

  The positioning means 1103 acquires location information about the current location of the mobile station. The storage unit 1105 holds communication environment information including distribution information with respect to the current position regarding communication quality of a plurality of communication methods, and a program. The communication unit 1104 is controlled by the program and communicates with the base station using one of a plurality of communication methods. The control unit 1102 selects a communication method in which the communication unit 1104 communicates with the base station from a plurality of communication methods based on the communication quality indicated by the distribution information with respect to the position information acquired by the positioning unit 1103.

  FIG. 2 is a flowchart showing an example of a procedure of the communication method switching method according to the embodiment of the present invention.

  The mobile station 101 receives position information by the positioning means 1103 (step S201). Based on the acquired position information, the transmission / reception method at the current position is selected by referring to the distribution information about the transmission / reception method held in the storage unit 1105. The control unit 1102 determines whether it is necessary to switch the current communication method, and instructs the communication unit 1104. That is, if it is determined from the distribution information held in the storage unit 1105 that the communication mode (mode) needs to be switched at the current position (YES in S202), the current mode is switched (step S203). If it is determined that switching in the current mode is not necessary, communication in the current mode is continued (step S204).

According to the mobile station according to the present embodiment, the communication range of the mobile device is expanded by switching the communication method based on the position information, and the same is true in an area where only one of the communication methods is possible. In addition, stable communication is possible.
[Second Embodiment]
[Constitution]
FIG. 3 shows an example of the configuration of a mobile station according to the second embodiment of the present invention.

  The mobile station 101 according to the present embodiment includes a data transmission / reception unit 104 that transmits / receives data to / from a base station, a GPS reception unit 103, a storage unit 105, a control unit 102, and an input / output interface 107. The GPS receiving unit 103 is a positioning unit that acquires information about the current position with reference to a signal from a satellite in the sky. The storage unit 105 holds communication state information about the current position and distribution information about the transmission / reception method.

  Here, the distribution information selects either a digital transmission / reception method or an analog transmission / reception method for a position on a plane specified by coordinate values such as latitude and longitude obtained by positioning with GPS. This is information that can be referred to. For example, the index value indicates which transmission / reception method should be selected for the plane coordinate value indicating the current position. Interpolation processing is performed as necessary to obtain index values. This index value indicates the communication quality by each transmission / reception method. Based on this distribution information, for example, an area on which a digital transmission / reception system should be selected and an area on which an analog transmission / reception system should be selected can be defined on a map.

  The control unit 102 includes an A / D switching control unit 106 that appropriately switches the transmission / reception method of the data transmission / reception unit 104 between the analog transmission / reception method (A) and the digital transmission / reception method (D).

  The input / output interface 107 allows the user to input voice or the like to the mobile station and reproduce the voice from the communication partner.

  FIG. 4 shows an example of the configuration of the communication system according to the present embodiment.

  In this embodiment, the base station is a digital wireless base station 301 that transmits and receives signals to and from the mobile station 101 by wireless communication using a digital transmission / reception method, and an analog wireless that transmits and receives signals to and from the mobile station 101 by wireless communication using an analog transmission / reception method. Base station 302.

  When the mobile station 101 can communicate with both the digital radio base station 301 and the analog radio base station 302 with sufficient signal strength, the mobile station 101 performs data communication using a digital transmission / reception method (hereinafter referred to as a digital mode). When the mobile station 101 moves and can communicate with only the analog radio base station 302 with sufficient signal strength, data communication is performed by an analog transmission / reception method (hereinafter referred to as an analog mode).

  The configuration of the communication system according to this embodiment shown in FIG. 4 can be applied to, for example, a fire fighting radio system. In this configuration, the analog mode is a 150 MHz band analog radio system, the digital mode is a 260 MHz band digital radio system, and these radio systems are used together.

In FIG. 4, the digital radio base station 301 that performs data communication in the digital mode and the analog radio base station 302 that performs data communication in the analog mode are separated, but the present invention is not limited to this. One base station may be configured to perform data communication in the digital mode and data communication in the analog mode. As described above, depending on whether the signal to be communicated is digital mode or analog mode, there is a difference between the two modes in the nature of carrier wave propagation, so even if the position of the base station is the same, Digital mode signals are not always received with the same strength.
[Operation]
FIG. 5 is a flowchart showing an example of a procedure of the communication method switching method according to the embodiment of the present invention.

  The mobile station 101 operates in a digital mode if possible in order to maintain the sound quality of input / output voices and the confidentiality of communication data (step S401).

  The mobile station 101 receives position information from the GPS receiver 103 at an appropriate time after movement or periodically at predetermined time intervals (step S402). Based on the acquired position information, the transmission / reception method at the current position is selected with reference to the distribution information about the transmission / reception method held in the storage unit 105. If there is information on the transmission / reception method at the current position (YES in S403), the A / D switching control unit 106 determines whether or not the current communication method (mode) needs to be switched, and instructs the data transmission / reception unit 104. . That is, if data communication is currently being performed in the digital mode and the distribution information held in the storage unit 105 determines that the signal strength in the digital mode is insufficient at the current position (YES in S404), the digital mode Is switched to analog mode data communication (step S405). If it is determined that the signal strength in the digital mode at the current position is sufficiently strong, data communication in the digital mode is continued (step S406). If data communication is currently being performed in the analog mode and the index value of the mode for the current position is referred to from the distribution information held in the storage unit 105, and it is determined that the signal strength of the digital mode is sufficiently high (YES in S404) ), The data communication in the analog mode is switched to the data communication in the digital mode (step S405).

  At this time, when the control unit 102 determines that the distribution information held in the storage unit 105 needs to be changed (YES in S407), the control unit 102 updates the distribution information. That is, when the mode indicated in the distribution information held for the current position is different from the mode currently being communicated, or communication is performed in the mode indicated in the distribution information, it is determined that the signal strength is not sufficient. If it is, the mode index value for the current position is rewritten. If it is determined that no change is necessary (NO in S407), the update process is not performed.

  The communication environment changes over time. Communication using a carrier wave having a relatively low frequency such as an analog transmission / reception system may be difficult to receive radio waves due to the weather. In addition, when a new building appears or is removed, the communication environment in the digital transmission / reception system with a high carrier frequency easily changes. Moreover, in the train radio system disclosed in Patent Document 4, when the mobile station moves to a point away from the track, the transmission / reception method cannot be selected.

  Whether or not the distribution information needs to be changed may be determined based on whether the mobile station is in communication after switching or continuing the mode. Alternatively, the signal intensity in each mode may be detected and a determination may be made based on the detection result.

  FIG. 6 shows an example of a procedure for detecting the signal intensity after mode switching or continuing and determining whether or not the distribution information needs to be updated based on the result.

  FIG. 7 shows an example of the communication state information about the position held by the storage unit 105 based on the position information acquired by the GPS receiving unit 103.

  The time and position acquired by the GPS receiving unit 103 are entered in the cell of the table of FIG. The position at which the mobile station 101 is present, the signal reception strength in the analog mode and the signal reception strength in the digital mode at this position are detected (step S409 in FIG. 6), and the detected value is stored in the cell of FIG. Filled in.

  Further, information about the base station as a communication partner with which the mobile station 101 establishes a communication path may be entered. The base station of the communication partner is specified by the base station identification information included in the transmission radio wave emitted by the base station.

  Based on the reception strength of the signal in each transmission / reception method, it is determined whether or not further switching is required from the transmission / reception method selected in step S404 (step S410). If it is determined that switching is necessary (YES in S410), the current mode is switched (step S411). If it is determined that switching is not necessary (NO in S410), the current mode is continued (step S412).

  The transmission / reception method determined at this point is entered in the mode column in the table of FIG.

  When it is determined in step S410 that switching is necessary, that is, when the distribution information about the transmission / reception method held in the storage unit 105 is different from the result of the measured signal strength, the result of the measured value. Is prioritized and it is determined that the stored distribution information needs to be changed (YES in S407). The distribution information is updated based on the result of the actual measurement value recorded as the communication state information illustrated in FIG. 7 (step S408).

  FIG. 8 shows an example of distribution information about the transmission / reception method held in the mobile station 101 according to the present embodiment. On the map corresponding to the position information acquired by the GPS receiving unit 103, an area in which only communication in the analog mode is possible, an area in which communication in the analog mode and communication in the digital mode are possible, An area where communication is also impossible is shown. Although there may be a region where communication in the analog mode is impossible and communication in the digital mode is possible, illustration is omitted in FIG.

  The distribution information shown in FIG. 8 may include information such as the position of the base station and the intensity of the transmission radio wave. In FIG. 8, the area on the map is classified into three areas in which neither the digital mode nor the analog mode is possible, but the present invention is not limited to this. The index value of each mode may be further classified into a plurality of levels according to the signal strength or the like, and a continuous value as the index value may be held at a predetermined position on the map. Further, the mode index value may include information on each communication method in the digital mode.

  The distribution information in FIG. 8 is updated based on the communication state information about the position shown in FIG. A region demarcation process is performed based on information obtained at each point on the map. That is, when the index value of each mode at a point on the map is changed from the digital mode to the analog mode, for example, the point leaves the digital mode region and enters the analog mode region. As a result, the boundary line between the digital mode region and the analog mode region is changed on the map. When the information of the newly added point is obtained, the accuracy of the boundary line of the area on the map becomes high.

  In addition, with reference to the distribution information shown in FIG. 8, when it is determined that the information about the transmission / reception method of the current position is in a reliable area based on the position acquired by the GPS receiver, step S409 to step S408 are performed. The procedure up to may be omitted. As a result, processing necessary for determining the transmission / reception method is reduced.

  Further, when the distribution information at the current position is not so reliable (NO in S403), the transmission / reception method is determined based on the measured value of the signal strength without performing the mode switching determination according to the distribution information of FIG. Based on the determined transmission / reception method and position information, the distribution information of the transmission / reception method is updated (step S408).

  In the related art, switching between the digital mode and the analog mode is determined by receiving the transmission radio wave from the base station and comparing the intensity. That is, the mode switching process is started after confirming that it is difficult to receive the transmission radio wave during communication.

  On the other hand, according to the communication method switching method according to the present embodiment, it is determined which mode of communication is performed based on the current position of the mobile station. When is not in the service area, the base station does not need to emit transmission radio waves. Thereby, the power consumption of the base station can be reduced.

  The establishment of the communication path at the time of mode switching is performed by the following procedure, for example. That is, when the mobile station 101 makes a call for the first time, the mobile station 101 sends a signal in a mode selected from the digital mode and the analog mode based on the current position acquired by the GPS receiver and the distribution information. To emit. The base station that performs communication in the selected mode receives this and responds with a signal necessary for establishing communication. The mobile station 101 establishes communication by detecting a base station identification signal included in the signal returned from the base station.

  If the response signal in the selected mode is not obtained, or if it is determined that the response signal is not strong enough, the mobile station 101 gives up communication in the selected mode, and in the other mode The process for establishing the communication path of is started.

  In addition, a plurality of base stations located at geographically distant locations may respond to signals transmitted from the mobile station 101. In such a case, the base station with the higher response signal strength may be selected for establishing the communication path. Alternatively, based on the distribution information held by the storage unit of the mobile station 101, the base station that is more likely to maintain communication for a longer time may be selected in consideration of the direction in which the mobile station moves.

  When the base stations 301 and 302 make a call for the first time at the start of communication, location registration information periodically sent from the mobile station 101 is detected, and a communication method is selected based on this.

  When a valid signal is not detected in the position registration information transmitted from the mobile station 101, a signal is transmitted from both the digital radio base station 301 and the analog radio base station 302. A communication method is selected based on the response to this signal returned from the mobile station 101. Even in the case where a plurality of mobile stations are present and communicate with all the mobile stations all at once, signals may be transmitted from both the digital radio base station 301 and the analog radio base station 302.

  In the communication system according to the present embodiment, the radio transceiver unit of the mobile station radio apparatus is configured by software radio. As a result, the mobile station can support both the digital transmission / reception system and the analog transmission / reception system with a small configuration.

  By switching the communication method, the communication range of the mobile device is expanded, and stable communication is possible similarly in an area where only analog transmission / reception is possible or an area where only digital transmission / reception is possible.

  According to the communication method switching method according to the present embodiment, an appropriate communication method is automatically selected from the analog mode and the digital mode based on the position information acquired by the GPS receiving unit 103. As a result, even if the signal strength in the digital mode decreases due to movement of the mobile station 101, the user does not need to worry about changing the communication method.

  Based on the distribution information of the communication environment of the analog communication system and the distribution environment of the digital communication system, the position of the mobile device is detected by a positioning means such as GPS, and which communication system is selected. It is determined whether to select at the time. The distribution information of the communication environment is sequentially updated based on the position information acquired by positioning and the actually measured value information about the communication quality in the selected communication method.

In addition, by actually measuring the signal intensity at the moved position and determining which communication method to select, and updating the distribution information based on this, the distribution of the communication state that changes with time is stored in the storage unit 105. It can be automatically reflected in the distribution information held. This makes it possible to select a highly accurate communication method based on the latest distribution information. Thereby, the distribution information of the communication environment can be obtained corresponding to the communication environment changing with time.
[Modification]
In the embodiment of the present invention, the distribution information is updated with the position information acquired by the GPS receiving unit 103, but the present invention is not limited to this.

  For example, the updated distribution information is periodically transmitted to the base station, and the base station accumulates the update information and periodically distributes the updated information to all the mobile stations. Can be shared on As a result, the latest accurate distribution information can be acquired even for a mobile station with little movement, and the communication method can be determined even at the first visit location.

  By notifying this update information to other communication devices, the latest distribution information is shared and efficient update processing becomes possible.

  If the mobile station 101 has sufficiently accurate distribution information, the procedure from step S409 to step S408 in FIG. 6 can be omitted. As a result, the time and processing required to detect the signal intensity and update the distribution information can be reduced, so that power consumption can be suppressed.

  Further, in a communication system in which data is communicated by a digital communication method such as SCPC, there are cases where there is no usable channel even when the digital mode is selected. In such a communication system, switching means for automatically switching the communication method to the analog mode may be provided.

  Further, the movement of the mobile station 101 is detected based on the position information acquired by the GPS receiving unit 103, and the switching timing of the communication method is predicted based on the distribution information about the transmission / reception method as shown in FIG. It is possible. As a result, the communication method can be switched to the analog mode before the communication quality deteriorates due to the decrease in the digital signal strength, so that the data communication can be continued while maintaining the communication quality.

  Based on the elapsed time of the location information acquired by positioning, the mobile device's movement direction and speed are calculated, and the communication system switching time is predicted from the distribution information of the communication environment so as to avoid deterioration in communication quality. Can also be scheduled. Switching processing considering the delay time required for switching is possible, and communication quality is stabilized.

  Further, when switching the communication method, it cannot be determined whether the communication quality of the other communication method of the switching destination is superior even at the position where the mobile station has moved thereafter. For example, if the communication quality of the digital signal is degraded due to accidental entry into the shadow, it may be expected that the communication quality of the digital signal will be recovered when coming out of the shadow. When the mobile station is in such a state, it may have means for suggesting the movement of the mobile device. In this case, communication can be maintained by changing the position of the mobile device rather than changing the communication method.

  Furthermore, even if the signal strength is equal to or higher than a threshold necessary for maintaining communication, the communication quality may not be sufficient. In such a case, there is a case where it is desired to maintain the communication in the digital mode even if the deterioration of the communication quality is allowed. In addition, when the signal strength in the analog mode is a sufficiently large value in a wide range, it may be desired to maintain communication in the analog mode as much as possible. A setting unit that can set the priority of the digital mode and the priority of the analog mode according to the user's request may be provided.

  A program for executing the above-described processing operations is stored and distributed in a computer-readable recording medium such as a flexible disk, a CD-ROM (Compact Disk Read-Only Memory), and an MO (Magneto-Optical disk). A device that executes the above-described processing operation may be configured by installing the program in a computer.

  The present invention is not limited to the above-described embodiment, and can be suitably applied to a communication system capable of communication using a plurality of communication methods.

DESCRIPTION OF SYMBOLS 101 Mobile station 102 Control part 103 GPS receiving part 104 Data transmission / reception part 105 Storage part 106 A / D switching control part 107 Input / output interface 301 Digital radio base station 302 Analog radio base station 1102 Control means 1103 Positioning means 1104 Communication means 1105 Storage means

Claims (8)

A mobile station that communicates with a base station that communicates with a plurality of different communication methods,
Positioning means for acquiring position information about the current position of the mobile station;
Communication environment information including distribution information for the current position with respect to communication quality of the plurality of communication methods, storage means for holding a program,
Communication means controlled by the program to communicate with the base station in one of the plurality of communication methods;
Control means for selecting a communication method in which the communication means communicates with the base station from the plurality of communication methods based on communication quality indicated by the distribution information with respect to the position information acquired by the positioning means;
Switching means for switching the selected communication method to another communication method different from the selected communication method among the plurality of communication methods when there is no communication channel usable in the communication method selected by the control means. And
The control means, when the selected communication method at the current position is different from the communication method indicated by the distribution information for the current position, or the signal strength in the communication method indicated by the distribution information The mobile station is characterized in that the distribution information is updated when it is determined that is not sufficient.   Based on the movement direction and movement speed of the mobile station acquired based on the position information acquired by the positioning means and the communication environment information, the control means switches the communication method of the communication means. The mobile station according to claim 1, wherein the mobile station is predicted. The communication means notifies the update information about the update of the communication environment information to the base station, receives distribution information distributed at a predetermined time by the base station,
The mobile station according to claim 1, wherein the control unit updates the communication environment information based on the received distribution information.   The mobile station according to any one of claims 1 to 3, wherein the control means suggests movement of the mobile station based on communication quality of communication by the communication means. A communication system comprising: the mobile station according to claim 1; and a base station that communicates with the mobile station. The mobile station communication means notifies the base station of update information about the update of the communication environment information,
The base station generates distribution information based on the update information, and transmits it to the mobile station at a predetermined time,
6. The communication system according to claim 5, wherein the control unit of the mobile station updates communication environment information of the mobile station based on the distribution information. A communication method switching method for switching a communication method for communication between a base station and a mobile station that communicate with each other by a plurality of different communication methods,
Obtaining location information about the current location of the mobile station;
Referring to communication quality for the position information from communication environment information including distribution information for the current position for communication quality of the plurality of communication methods;
Selecting a communication method for communication between the base station and the mobile station from the plurality of communication methods based on the referenced communication quality;
When there is no communication channel that can be used in the communication method selected in the step of selecting the communication method, the selected communication method is changed to another communication method different from the selected communication method among the plurality of communication methods. Step to switch to
When the selected communication method at the current position is different from the communication method indicated by the distribution information for the current position, or the signal strength in the communication method indicated by the distribution information is not sufficient And a method for switching the distribution information when the communication method is switched. A communication method switching program for switching a communication method for communication between a base station and a mobile station that communicate with each other by a plurality of different communication methods,
A process of obtaining location information about the current location of the mobile station;
Processing for referring to communication quality for the position information from communication environment information including distribution information for the current position for communication quality of the plurality of communication methods;
Based on the referenced communication quality, a process of selecting a communication method for communication between the base station and the mobile station from the plurality of communication methods;
When there is no communication channel that can be used in the communication method selected in the process of selecting the communication method, the selected communication method is changed to another communication method different from the selected communication method among the plurality of communication methods. The process of switching to
When the selected communication method at the current position is different from the communication method indicated by the distribution information for the current position, or the signal strength in the communication method indicated by the distribution information is not sufficient In this case, a communication system switching program that causes a computer to perform the process of updating the distribution information.

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