JP4925211B2 - Wireless communication system and mobile communication terminal - Google Patents

Description

  The present invention relates to a radio communication system and a mobile communication terminal, and more particularly to a radio communication system in which a mobile communication terminal has a plurality of radio communication units and performs communication while performing handover between a plurality of base stations.

  2. Description of the Related Art Conventionally, communication systems that allow base stations and mobile communication terminals to be wirelessly connected by a wireless LAN or the like and enable communication while moving are widely used.

  As the communication system, there is a system in which a communication frequency band is finely assigned to set a plurality of radio channels, and they are used while being switched according to communication conditions. For example, Patent Document 1 discloses an SN ratio of each radio channel. And a communication system that selects a channel in which the highest S / N ratio is detected as a communication channel is described. According to this system, since a channel having a good SN ratio is always selected as a communication channel, a good communication state can be maintained regardless of the movement status of the mobile communication terminal.

  In addition, as the communication system, there is a system that establishes communication while moving (handover) between a plurality of base stations. For example, in Patent Document 2, a plurality of wireless communication units are provided in a mobile communication terminal for communication purposes. A communication system is described in which a base station search is performed by other wireless communication units while communicating with the selected wireless communication unit. According to this system, it is possible to determine the connection destination base station prior to the handover, and therefore it is possible to reduce the time required for executing the handover.

JP 2003-244761 A JP 2005-341453 A

  In the communication system, the selection of the radio channel switching destination and the handover destination is determined based on information obtained by the channel setting unit and the radio communication unit (for example, information on the electric field strength). Since the information obtained from the information is influenced by external waves, reflections, and wraparound, there is a possibility that the radio channel and the base station are not correctly selected. In particular, in an environment where there are many structures and shielding objects, the communication environment changes drastically depending on the movement status of the mobile communication terminal, so it should be selected due to a temporary decrease in the electric field strength accompanying the movement of the mobile communication terminal. The wireless communication unit is not selected, and the communication performance may be deteriorated.

  Therefore, the present invention has been made in view of the above-described problems in the conventional technology, and in a wireless communication system that performs handover between a plurality of base stations, even in an environment where structures and shielding objects exist. An object of the present invention is to provide a system or the like that can increase the accuracy of selecting a handover destination and can improve reliability by continuing stable communication.

In order to achieve the above object, the present invention comprises a plurality of base stations connected to a network, and a mobile communication terminal having a plurality of radio communication units wirelessly connected to each of the plurality of base stations. A communication terminal is a wireless communication system in which one of the plurality of wireless communication units is selected as a wireless communication unit for communication and wirelessly connected to the network, wherein the mobile communication terminal includes a plurality of wireless communication units A communication state detecting means for detecting a communication state; a position detecting means for detecting a position of the mobile communication terminal; a selection history of the plurality of wireless communication units in association with the position information; and an electric field of the plurality of wireless communication units a selection history recording means intensity records the field strength information indicating the highest radio communication unit, when the communication state of said plurality of wireless communication unit detected by the communication condition detecting means is good, the location Based on the position detected by the output unit and the selection history recorded in the selection history recording unit, the wireless communication unit with the largest number of selections among the plurality of wireless communication units is selected as the wireless communication unit for communication And selecting means for selecting the selection history recording means based on the electric field strength information when the communication state is not good as a result of communication using the selected wireless communication unit. It is characterized by correcting the history .

According to the present invention, when selecting a wireless communication unit for communication, the wireless communication unit is determined based on the number of past selections. The wireless communication unit to be selected can always be selected without being influenced by As a result, even in an environment where there are structures and shielding objects, the accuracy of selecting a handover destination can be increased, and stable communication can be continued to improve reliability. Further, when the communication state is not good, the selection history is corrected based on the electric field strength information, so that the selection accuracy of the wireless communication unit can be further improved.

The present invention also provides a mobile communication terminal having a plurality of wireless communication units that are wirelessly connected to different base stations, and performing communication processing by selecting one of the plurality of wireless communication units as a wireless communication unit for communication The communication status detection means for detecting the communication status of the plurality of wireless communication sections, the position detection means for detecting the position of the mobile communication terminal, and the selection history of the plurality of wireless communication sections in association with the position information And a selection history recording unit that records field strength information indicating a wireless communication unit having the highest electric field strength among the plurality of wireless communication units, and communication between the plurality of wireless communication units detected by the communication state detection unit When the state is good, based on the position detected by the position detecting unit and the selection history recorded in the selection history recording unit, the wireless communication with the largest number of selections among the plurality of wireless communication units Part for the communication And selecting means for selecting the wireless communication unit, the selection unit, the selection result of the communication using the wireless communication unit selected, when the communication state is not good, based on the field strength information The selection history of the history recording means is corrected . According to the present invention, as in the case of the above-described invention, even in an environment where there are structures and shielding objects, the accuracy of selecting a handover destination can be improved, and stable communication can be continued to improve reliability. As a result, it is possible to improve the selection accuracy of the wireless communication unit .

  In the mobile communication terminal, when the selection unit has a single radio communication unit with a good communication state, the selection unit selects the radio communication unit as the radio communication unit for communication, and the radio with a good communication state. When there are a plurality of communication units, it is possible to select a radio communication unit with the largest number of selections from among a plurality of radio communication units in good communication state as the radio communication unit for the communication.

  As described above, according to the present invention, in a wireless communication system that performs handover between a plurality of base stations, the accuracy of selecting a handover destination can be improved even in an environment where a structure or a shield exists. It becomes possible to continue stable communication and improve reliability.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an overall configuration diagram showing an embodiment of a wireless communication system according to the present invention. In the following description, in the wireless communication system according to the present invention, the upper apparatus 1 remotely monitors the lower apparatus 10 through the fixed network 2 under a predetermined area (closed area) such as a premises or a store. The case where it applies to a system is illustrated.

  As shown in FIG. 1, the wireless communication system includes a host device 1 wired to a fixed network 2, first and second base stations 3 and 4 wired to the fixed network 2, And a mobile communication terminal 11 including a lower level device 10 that is wirelessly connected to the second base stations 3 and 4.

  The mobile communication terminal 11 includes a first wireless communication unit 12 that communicates with the first base station 3, a second wireless communication unit 13 that communicates with the second base station 4, and the first and second wireless communication units 12 and 13. The communication control part 14 which controls the communication state between the low-order apparatus 10 and the GPS apparatus 15 which detects the position of the mobile communication terminal 11 using a GPS function is provided. The communication control unit 14 includes a communication unit 16 that transmits and receives signals to and from the lower level device 10, a route selection unit 17 that selects a communication path when a response signal is transmitted from the lower level device 10 to the higher level device 1, Selection information recording means 19 for recording a route selection history or the like in the selection history storage area 18 is included.

  In the selection history storage area 18, as shown in FIG. 2, the location information of the mobile communication terminal 11 is recorded, and the past three route selection histories and the previous route selection are associated with the location information. Sometimes, field strength information indicating the wireless communication unit on the side where the field strength is high is recorded. Here, “1” in the figure indicates the first wireless communication unit 12, and “2” indicates the second wireless communication unit 13.

  Next, the operation of the wireless communication system having the above configuration will be described with reference to FIGS. Here, first, a case where a control signal is transmitted from the upper apparatus 1 to the lower apparatus 10 will be described.

  In the transmission of the control signal, as shown in FIG. 3, first, the upper apparatus 1 sends the control signal to the lower apparatus 10 via the fixed network 2 to both the first and second base stations 3 and 4. (Step S1). After that, after waiting for a predetermined time, it is determined whether or not a response signal is transmitted from the lower level device 10 (step S2). If the response signal is received, the next control signal is waited for transmission. (Step S3) If the response signal is not received, the same signal as the control signal transmitted last time is retransmitted (Step S4).

  When the control signal is transmitted from the host device 1, on the mobile communication terminal 11 side, as shown in FIG. 4, the first radio communication unit 12 receives the control signal from the first base station 3, and the second radio communication unit 13 receives the control signal from the second base station 4 and notifies the communication control unit 14 thereof (step S5). Next, the communication control unit 14 determines whether or not the received control signal has been retransmitted (step S6). If it has not been retransmitted, the communication control unit 14 controls the lower apparatus 10 through the communication means 16. The signal is transferred (step S7). On the other hand, if the control signal is retransmitted, the recorded information in the selection history storage area 18 is corrected by the selection information recording means 19 (step S8), which will be described later.

  Next, a case where a response signal is transmitted (returned) from the lower apparatus 10 to the upper apparatus 1 will be described.

  When the control signal is received from the upper apparatus 1 by the above operation, as shown in FIG. 5, first, the lower apparatus 10 transmits a response signal to the communication means 16 of the communication control unit 14 (step S11). Next, the route selection unit 17 of the communication control unit 14 confirms the operating status of the first wireless communication unit 12 and determines whether or not the first wireless communication unit 12 is operating (step S12). Here, “in operation” means that the first wireless communication unit 12 can communicate with the communication control unit 14 and can detect and communicate with the first base station 3. The operation status of the first wireless communication unit 12 is confirmed by periodically exchanging a predetermined signal between the communication control unit 14 and the first wireless communication unit 12.

  As a result of the determination, when the state of the first wireless communication unit 12 is “carrier not detected” or “function stopped” and is not in operation (step S12: No), the route selection unit 17 determines that the second wireless communication unit 12 The operating status of the communication unit 13 is confirmed, and it is determined whether or not the second wireless communication unit 13 is operating (step S13). As a result, when the second wireless communication unit 13 is in operation, the second wireless communication unit 13 is selected as a wireless communication unit for communication (step S14). Since both the second wireless communication units 12 and 13 cannot be used, the transmission of the response signal is stopped.

  Further, even when the state of the first wireless communication unit 12 is in operation (step S12: Yes), the route selection unit 17 determines whether or not the second wireless communication unit 13 is in operation ( Step S15) If the second wireless communication unit 13 is not in operation, the first wireless communication unit 12 is selected as a communication wireless communication unit (step S16).

  On the other hand, when both the first and second wireless communication units 12 and 13 are in operation (step S15: Yes), the route selection unit 17 uses the GPS device 15 to obtain the position information of the mobile communication terminal 11. (Step S17). Here, it is assumed that the content of the acquired position information is “X2, Y3”.

  Next, the route selection unit 17 refers to the selection history storage area 18 using the acquired position information (step S18), and extracts a selection history corresponding to the position (X2, Y3) (see FIG. 2A). . Then, the wireless communication unit having the largest number of selections in the past three selection processes is determined, and the wireless communication unit is selected as a wireless communication unit for communication (step S19). Here, as shown in FIG. 2A, since the second wireless communication unit 13 is selected many times, the second wireless communication unit 13 is selected as a wireless communication unit for communication.

  When the wireless communication unit is selected as described above, the oldest selection history (selection history three times before) in the selection history storage area 18 is deleted by the selection information recording unit 19 as shown in FIG. Then, the current selection result is recorded as the latest selection history (the previous selection history) (step S20). At the same time, the electric field strengths of the first and second radio communication units 12 and 13 are confirmed, and the radio communication unit having the higher electric field strength is recorded in the electric field strength information (see FIG. 2B) and selected. The recorded contents of the history storage area 18 are updated. At this time, the selection information stored as the selection history of the previous time and the previous time is rewritten as the selection history of the previous time and the previous time, respectively.

  When the update of the selection history storage area 18 is completed, a response signal is transmitted from the lower level device 10 to the communication means 16 of the communication control unit 14, and is output toward the fixed network 2 through the selected wireless communication unit (step S21). At this time, if the selection of the wireless communication unit performed in steps S12 to S19 is appropriate, the response signal is transmitted to the fixed network 2 and transmitted to the host device 1.

  On the other hand, when the selection of the wireless communication unit is not appropriate, the response signal is not transmitted to the host device 1, and the host device 1 retransmits the same control signal as shown in FIG. S2, S3). Then, as shown in FIG. 4, the retransmitted control signal is received by the mobile communication terminal 11 through the first and second wireless communication units 12 and 13 (step S5), and in the subsequent determination process (step S6), It is determined that the control signal is a retransmission control signal.

  As a result of the determination, the route selection unit 17 recognizes that the previous selection was not appropriate, and thereafter, through the selection information recording unit 19, the previous selection result recorded in the selection history storage area 18 ( 2a-1) is rewritten to the electric field strength information (information indicating the wireless communication unit on the side where the electric field strength is higher) recorded in step S20 of FIG. 5 (step S8 of FIG. 4). As a result, the contents of the selection history are changed and reflected in the next selection process.

  As described above, according to the present embodiment, when selecting a wireless communication unit for communication, since the wireless communication unit is determined based on the number of past selections, the selection result of the wireless communication unit is temporary. A wireless communication unit to be selected can be selected at any time without being influenced by changes in the communication environment. As a result, even in an environment where there are structures and shielding objects, the accuracy of selecting a handover destination can be increased, and stable communication can be continued to improve reliability.

  In addition, according to the present embodiment, field strength information is recorded in the selection history storage area 18 in addition to the selection history of the wireless communication unit, and if the selection result is not appropriate, based on the field strength information. Since the selection history is corrected, the selection accuracy can be further improved.

  In the above-described embodiment, the case where there are two base stations and two wireless communication units is illustrated, but the number thereof may be three or more. In this case, when a single wireless communication unit is in operation, the wireless communication unit is selected as a wireless communication unit for communication, and there are a plurality of active wireless communication units. Sometimes, it can be performed by selecting the wireless communication unit having the largest number of selections as the wireless communication unit for communication.

1 is an overall configuration diagram showing an embodiment of a wireless communication system according to the present invention. It is a figure which shows the information recorded on the selection log | history memory area of FIG. It is a flowchart which shows the transmission procedure of a control signal. It is a flowchart which shows the reception procedure of a control signal. It is a flowchart which shows the transmission procedure of a response signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Host apparatus 2 Fixed network 3 First base station 4 Second base station 10 Lower apparatus 11 Mobile communication terminal 12 1st wireless communication part 13 2nd wireless communication part 14 Communication control part 15 GPS apparatus 16 Communication means 17 Path selection means 18 Selection history storage area 19 Selection information recording means

Claims (3)

A plurality of base stations connected to a network, and a mobile communication terminal having a plurality of radio communication units wirelessly connected to each of the plurality of base stations, the mobile communication terminal being one of the plurality of radio communication units A wireless communication system for selecting a wireless communication unit for communication and wirelessly connecting to the network,
The mobile communication terminal is
Communication state detecting means for detecting communication states of the plurality of wireless communication units;
Position detecting means for detecting the position of the mobile communication terminal;
Selection history recording means for recording selection history of the plurality of wireless communication units in association with position information and field strength information indicating a wireless communication unit having the highest electric field strength among the plurality of wireless communication units ;
Based on the position detected by the position detection means and the selection history recorded in the selection history recording means when the communication status of the plurality of wireless communication units detected by the communication status detection means is good A selection means for selecting a wireless communication unit having the largest number of selections among the plurality of wireless communication units as the wireless communication unit for communication ,
The selection unit corrects the selection history of the selection history recording unit based on the electric field strength information when the communication state is not good as a result of performing communication using the selected wireless communication unit. A wireless communication system. A mobile communication terminal that has a plurality of wireless communication units that are wirelessly connected to different base stations, performs communication processing by selecting one of the plurality of wireless communication units as a wireless communication unit for communication,
Communication state detecting means for detecting communication states of the plurality of wireless communication units;
Position detecting means for detecting the position of the mobile communication terminal;
Selection history recording means for recording selection history of the plurality of wireless communication units in association with position information and field strength information indicating a wireless communication unit having the highest electric field strength among the plurality of wireless communication units ;
Based on the position detected by the position detection means and the selection history recorded in the selection history recording means when the communication status of the plurality of wireless communication units detected by the communication status detection means is good A selection means for selecting a wireless communication unit having the largest number of selections among the plurality of wireless communication units as the wireless communication unit for communication ,
The selection unit corrects the selection history of the selection history recording unit based on the electric field strength information when the communication state is not good as a result of performing communication using the selected wireless communication unit. Mobile communication terminal.   The selection unit selects a wireless communication unit as the communication wireless communication unit when there is a single wireless communication unit with a good communication state, and there are a plurality of wireless communication units with a good communication state. 3. The mobile communication terminal according to claim 2, wherein a radio communication unit with the largest number of selections is selected as the radio communication unit for the communication among the plurality of radio communication units in good communication state. .

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