JP2012151726A - Radio communication system and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a long time is required until establishment of radio connection due to a decrease in communication speed and an increase in collision probability of an access request signal, when mobile terminals are intensively connected to a specific radio base station.SOLUTION: A server 101 manages the number of mobile terminals connected to each base station capable of shifting a position. When determining that the number of the mobile terminals connected to a base station A102 reaches an upper limit value, the server 101 shifts a position of either of base stations B103 and C104, in which the number of the mobile terminals connected to the base station does not reach the upper limit value, so that its own communication range can partially overlap a communication range of the base station A102.

Description

  The present invention relates to a radio communication system and a radio communication method including a plurality of base stations and a plurality of mobile terminals.

  In recent years, with the advancement of digital wireless communication technology, wireless communication systems capable of high-speed transmission are widely used not only in offices and factories, but also in homes in general households.

  When these wireless communication systems are used in a wide space such as a company, a large store, or a large facility, a plurality of wireless base stations are distributed and installed in the space in order to increase the number of connected mobile terminals. The mobile terminal functions to select the radio base station to be connected by comparing the received power of the beacon signal transmitted by the radio base station.

  In the above method, when mobile terminals connected to a specific wireless base station are concentrated, the communication speed decreases, the collision probability of access request signals increases, and it takes time to establish a wireless connection. Occurs.

  For this problem, each radio base station shares the number of mobile radio terminals connected to its own station, and uses this shared information to transmit the beacon signal transmitted from its own station, There has been proposed a method of controlling the radio transmission rate with a connected mobile radio terminal and distributing the load of the radio base station (see, for example, Patent Document 1).

JP 2009-124461 A

  As described above, the method according to Patent Document 1 proposes a method of distributing the load of a radio base station. However, if mobile terminals connected to a specific radio base station are concentrated, the base station has already been concentrated. Since the connected wireless terminal communicates with a distant base station, the problem that communication quality deteriorates remains.

  The present invention has been made to solve such problems, and reduces degradation of communication quality when a wireless terminal already connected to a wireless base station is connected to another wireless base station. An object of the present invention is to provide a wireless communication system and a wireless communication method.

  To achieve the above object, a wireless communication system according to claim 1 of the present invention is a communication system including a plurality of mobile terminals and a plurality of base stations, and manages the arrangement of the plurality of base stations. The base station management unit, the plurality of base stations are movable, and the base station management unit has reached a predetermined upper limit for the number of connected mobile terminals for each base station. If there is a base station that has reached the upper limit value, one base station is selected from the base stations that have not reached the upper limit value, and the selected base station is selected. The base station communication range is moved so as to overlap a part of the communication range of the base station that has reached the upper limit value.

  A radio communication system according to a second aspect of the present invention is the radio communication system according to the first aspect, wherein each base station transmits the current number of connections to the base station management unit when performing radio connection with the mobile terminal. The base station management unit manages the number of connections transmitted from each base station, and determines whether the number of connections of each base station has reached the upper limit value using the number of connections.

  The wireless communication system according to claim 3 of the present invention is the wireless communication system according to claim 1, wherein each base station disconnects the wireless connection with the mobile terminal when the base station makes a wireless connection with the mobile terminal. In this case, the mobile terminal transmits a wireless connection with the mobile terminal or a connection state indicating disconnection of the wireless connection to the base station management unit, the base station management unit, according to the connection state transmitted from each base station, The number of connected base stations may be managed, and the number of connected base stations may be used to determine whether the number of connected base stations has reached the upper limit.

  A wireless communication system according to a fourth aspect of the present invention is the wireless communication system according to the first aspect, wherein when each base station performs a wireless connection with the mobile terminal, the current number of connections reaches the upper limit value. The base station management unit manages the connection state transmitted from the base station, and the connection state is used to determine the number of connected base stations. It is determined whether or not the upper limit value has been reached.

  In the wireless communication system, the base station management unit may select a base station with a small number of connected stations among base stations that have not reached the upper limit value.

  The base station management unit may select a base station located near the base station that has reached the upper limit value among base stations that have not reached the upper limit value.

  A radio communication system according to claim 9 of the present invention is the radio communication system according to claim 1, wherein each base station manages the number of connections between the base station management unit and the current mobile terminal. And when the number of connected units has reached the upper limit, the number of connected units has reached the upper limit of the number of connected units indicating that the number of connected units has reached the upper limit of other base stations. When the notification is transmitted and the base station management unit receives the connection number upper limit arrival notification, the base station management unit checks its own number of connections, and if the number of connections does not reach the upper limit, the upper limit is not reached. When the upper limit value is reached, one base station is selected from the base stations that are the source of the received mobility notification and selected. The communication range of the selected base station is within its communication range. It is to move so as to overlap a part range.

  A radio communication system according to claim 13 of the present invention is the radio communication system according to claim 1, wherein each base station manages the number of connections between the base station management unit and the current mobile terminal. And when the number of connected units has reached the upper limit, the number of connected units has reached the upper limit of the number of connected units indicating that the number of connected units has reached the upper limit of other base stations. When the base station management unit receives the connection number upper limit arrival notification, the base station management unit checks its own number of connections, and if the number of connections does not reach the upper limit, the base station moves itself The mobile station transmits a movable notification indicating that the upper limit value has not been reached to another base station, and a part of its own communication range is included in the communication range of the base station that has transmitted the connection number upper limit arrival notification. Move to overlap.

  Advantageous Effects of Invention According to the present invention, in a communication system in which mobile terminals move randomly, the communication capacity in a range where the mobile terminals are concentrated is increased, and the mobile terminal can continue stable communication and a wireless communication system. A communication method can be provided.

The block diagram which shows the example of 1 structure of the communication system which concerns on Embodiment 1 of this invention. The block diagram which shows the example of 1 structure of the server which concerns on Embodiment 1 of this invention. The block diagram which shows the example of 1 structure of the base station which concerns on Embodiment 1 of this invention. The figure which shows an example of the base station management table which concerns on Embodiment 1 of this invention. The flowchart which shows operation | movement of the base station which concerns on Embodiment 1 of this invention. The flowchart which shows operation | movement of the server which concerns on Embodiment 1 of this invention. The block diagram which shows the base station after the movement which concerns on Embodiment 1 of this invention The figure which shows an example of the base station management table which concerns on Embodiment 2 of this invention. The block diagram which shows the base station after the movement which concerns on Embodiment 2 of this invention The block diagram which shows the example of 1 structure of the communication system which concerns on Embodiment 3 of this invention. The block diagram which shows the example of 1 structure of the base station which concerns on Embodiment 3 of this invention. The figure which shows an example of the base station management table which concerns on Embodiment 3 of this invention. The flowchart which shows operation | movement of the base station which concerns on Embodiment 3 of this invention. The flowchart which shows operation | movement of the management base station which concerns on Embodiment 3 of this invention. The block diagram which shows the base station after the movement which concerns on Embodiment 3 of this invention The block diagram which shows the example of 1 structure of the base station which concerns on Embodiment 4 of this invention The figure which shows an example of the base station dispersion | distribution management table which concerns on Embodiment 4 of this invention. The flowchart which shows the movement request process of the base station which concerns on Embodiment 4 of this invention. The flowchart which shows the mobile response process of the base station which concerns on Embodiment 4 of this invention. Time chart showing operation of each base station according to Embodiment 4 of the present invention The figure which shows an example of the other base station dispersion | distribution management table which concerns on Embodiment 4 of this invention. The flowchart which shows the other movement request | requirement process of the base station which concerns on Embodiment 4 of this invention. The flowchart which shows the other mobile response process of the base station which concerns on Embodiment 4 of this invention. Time chart showing other operations of each base station according to Embodiment 4 of the present invention

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

(Embodiment 1)
A communication system according to Embodiment 1 of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a configuration of a communication system according to the first embodiment.

  In FIG. 1, a server 101 is connected to a base station A102, a base station B103, a base station C104, and an external network 100. Note that the server 101, the base station A102, the base station B103, the base station C104, and the external network 100 may be connected by wired communication or wireless communication.

  In FIG. 1, a server 101 is connected to a base station A102, a base station B103, a base station C104, and an external network 100 by wired communication. Base station A102, base station B103, and base station C104 are each a base station of a wireless communication system, and connect mobile terminals by wireless communication. Further, the base station A102, the base station B103, and the base station C104 can move their positions.

  In FIG. 1, a base station A102, a base station B103, and a base station C104 are installed at coordinate points x = 10, 20, and 30 with a certain coordinate reference point x = 0 as a reference. The mobile terminals 105, 106, 107, and 108 are connected to any of the base stations and perform wireless communication with the external network 100 or other mobile terminals. As shown in FIG. 1, mobile terminals 105, 106, and 107 are connected to base station A102, and mobile terminal 108 is connected to base station B103.

  FIG. 2 is a block diagram illustrating a configuration example of the server according to the first embodiment.

  As shown in FIG. 2, the server 101 according to the first embodiment includes a communication I / F 201, a base station management table 202, a base station management unit 203, and a CPU 204.

  The communication I / F 201 performs input / output processing of data communication with other devices such as signal transmission / reception, modulation / demodulation, access control, and TCP / IP processing (Transmission Control Protocol / Internet Protocol processing). The base station management table 202 stores the connection state of the mobile terminal of each base station managed by the server 101. The base station management unit 203 performs reception of the connection state of the mobile terminal from the base station, discovery of a base station in which the number of connected mobile terminals has reached the upper limit value, and management of the base station arrangement. The CPU 204 performs general-purpose processing.

  FIG. 3 is a block diagram showing a configuration example of the base station according to the first embodiment.

  As shown in FIG. 3, base station A102, base station B103, and base station C104 according to the first embodiment include communication I / F 301, CPU 302, number management unit 303, position movement control unit 304, and movement unit 305. .

  The communication I / F 301 performs input / output processing of data communication with other devices such as signal transmission / reception, modulation / demodulation, access control, and TCP / IP processing. The CPU 302 performs general-purpose processing such as application processing. The number management unit 303 manages the number of mobile terminals connected to the base station. The position movement control unit 304 receives the movement instruction information addressed to the own station transmitted from the base station management unit 203 of the server, calculates a control amount for moving to the instructed location, and notifies the movement unit 305 of it. Is. The moving unit 305 is a mechanism for moving the position of the base station based on information input from the position movement control unit 304 such as a wheel or a motor.

  FIG. 4 is a diagram showing an example of the base station management table according to the first embodiment. As shown in FIG. 4, the base station management table 202 stores the base station ID that can be uniquely identified by each base station and the number of mobile terminals connected to the corresponding base station, received by the base station management unit 203. To do. The base station management table may store the location of each base station in addition to the number of connected units.

  In the configuration of the communication system shown in FIG. 1, mobile terminals 105, 106, and 107 are connected to a base station A102, and a mobile terminal 108 is connected to a base station B103. Accordingly, as shown in FIG. 4, the base station management table 202 in this case is 3 as the number of mobile terminals connected to the base station whose base station ID is A and 1 as the number of mobile terminals connected to the base station whose base station ID is B. , 0 is stored as the number of connected mobile terminals of the base station whose base station ID is C.

  Hereinafter, the operation of the base station according to Embodiment 1 will be described using FIG.

  FIG. 5 is a flowchart showing the operation of the base station according to the first embodiment.

  The number management unit 303 sets a counter C indicating the number of connected mobile terminals to 0 at the start (for example, immediately after power-on) (step 501). When receiving the packet, the communication I / F 301 determines whether the received packet data is a connection request from the mobile terminal (step 502). In step 502, when the received packet data is a connection request from the mobile terminal, the communication I / F 301 notifies the number management unit 303, and the number management unit 303 indicates that the counter C indicates the number of connected mobile terminals. It is determined whether the upper limit has been reached (step 503). If it is determined in step 503 that the counter C has not reached the upper limit value, the number management unit 303 notifies the communication I / F 301 to perform connection processing with the mobile terminal that transmitted the connection request. Thereafter, the communication I / F 301 performs connection processing with the mobile terminal that transmitted the connection request (step 504). When notified from the communication I / F 301 that the connection process is completed, the number management unit 303 increments the counter C by 1 (step 505). The number management unit 303 notifies the updated value of the counter C to the server 101 via the communication I / F 301 (step 506), and returns to step 502. On the other hand, when the counter C determines that the counter C has reached the upper limit of the number of connected mobile terminals in step 503, it cannot be connected to a new mobile terminal, so it is connected to the communication I / F 301. Notify that processing is not performed. The communication I / F 301 receives the notification from the number management unit 303, ignores the connection request, and returns to step 502.

  In step 502, if the received packet data is not a connection request from the mobile terminal, the communication I / F 301 determines whether or not the received packet data is a disconnection request from the mobile terminal (step 507). . In step 507, if the received packet data is a disconnection request from the mobile terminal, the communication I / F 301 performs a disconnection process for wireless communication with the mobile terminal that has transmitted the disconnection request (step 508). When the disconnection process ends, the communication I / F 301 notifies the number management unit 303 that the disconnection process has ended. The number management unit 303 decrements the counter C by 1 (step 509). The number management unit 303 notifies the updated value of the counter C to the server 101 via the communication I / F 301 (step 506), and returns to step 502.

  In step 507, when the received packet data is not a disconnection request from the mobile terminal, the communication I / F 301 outputs the received packet to the CPU 302. The CPU 302 performs other processing such as application processing and processing related to position movement in accordance with the contents of the received packet (step 510), and returns to step 502.

  Next, the operation of the server 101 according to the first embodiment will be described with reference to FIG.

  FIG. 6 is a flowchart showing the operation of the server according to Embodiment 1 of the present invention.

  The communication I / F 201 determines whether there is a notification of the number of connected mobile terminals from any one of the base station A102, base station B103, and base station C104 (step 601). When there is no notification of the number of connected mobile terminals from any of the base station A 102, base station B 103, and base station C 104, the communication I / F 201 outputs the received packet to the CPU 204. The CPU 204 performs another process according to the received packet (step 606), and returns to step 601. On the other hand, when there is a notification of the number of connected mobile terminals from any of the base station A 102, the base station B 103, and the base station C 104, the communication I / F 201 outputs a notification of the number of connected terminals to the base station management unit 203. The base station management unit 203 updates the base station management table 202 based on the notification of the number of connected units from the base station (step 602).

  Next, the base station management unit 203 refers to the base station management table 202 and determines whether the number of connected base stations has reached the upper limit (step 603). In the first embodiment, the upper limit value of the number of connected devices is 3. The base station management unit 203 determines that the communication range of the base station A102 is congested because the number of connected base stations A102 stored in the base station management table 202 is 3. Next, the base station management unit 203 serves as a base station that moves one of the base stations B103 and C104 that have not reached the upper limit value and has a free space to a position that compensates for the communication range of the base station A102. Select (step 604).

  In the first embodiment, the number of connected mobile terminals, that is, the “base station with the smallest number of connected mobile terminals” is used as the selection criterion for the base station to be moved. In the case of the first embodiment, since the number of connected base stations B103 is 1 and the number of connected base stations C104 is 0, the base station management unit 203 selects the base station C104. The base station management unit 203 transmits movement instruction information for approaching the base station A102 to the selected base station C104 via the communication I / F 201 (step 605), and returns to step 601. Here, as the movement instruction information, for example, when each base station knows the position of each other, the base station ID of the base station whose number of connections has reached the upper limit is transmitted as the movement destination. When the base stations do not know each other's position, the server 101 manages the position information of each base station, and transmits the position information of the base station whose connected number has reached the upper limit as the destination.

  On the other hand, if the number of connected base stations stored in the base station management table 202 has not reached the upper limit value in step 603, the base station management unit 203 returns to step 601 without doing anything.

  FIG. 7 is a block diagram showing the position of the base station after movement according to the first embodiment.

  As shown in FIG. 7, the base station C104 that has received the movement instruction from the server 101 moves to the vicinity of the base station A102 (position of x = 12), and the communication of the base station A102 where the mobile terminals are concentrated. A connection request from the mobile terminal is awaited by setting a range overlapping a part of the range as a new communication range.

  As described above, according to such a configuration, in a communication system in which mobile terminals move randomly, the communication capacity in a range where the mobile terminals are concentrated can be increased, and the mobile terminals can continue stable communication.

(Embodiment 2)
In the first embodiment, the base station selection criterion for moving the number of connected mobile terminals is used. However, in the second embodiment, the position of the base station, that is, “not congested (that is, connection of mobile terminals). Among the base stations whose number has not reached the upper limit value, the base station selection criteria for moving the congested base station (that is, the base station closest to the base station whose number of connected mobile terminals has reached the upper limit value) The case will be described.

  Since the configuration of the communication system, the server, and the base station according to Embodiment 2 is the same as that of Embodiment 1, description thereof is omitted. The difference between the second embodiment and the first embodiment is only the information stored in the base station management table 202 and the operation of the base station management unit 203, and only these will be described.

  FIG. 8 is a diagram showing an example of the base station management table according to the second embodiment.

  As shown in FIG. 8, the base station management table 202 according to the embodiment is connected to the base station ID received by the base station management unit 203 and capable of uniquely identifying each base station, and the corresponding base station. Stores the number of mobile terminals and the location information of each base station.

  In the configuration of the communication system shown in FIG. 1, with reference to a certain coordinate reference point x = 0, a mobile station 105, 106, 107 is connected to a base station A102 at a position x = 10, and a base station at a position x = 20. A mobile terminal 108 is connected to B103. In addition, the mobile terminal is not connected to the base station C104 located at x = 30. Therefore, the base station management table 202 has 3 as the number of mobile terminals connected to the base station whose base station ID is A, 10 as the position information, 1 as the number of mobile terminals connected to the base station whose base station ID is B, and the position information as 20 is stored as 0 as the number of mobile terminals connected to the base station whose base station ID is C, and 30 is stored as position information.

  Next, the operation of the base station management unit 203 of the server 101 according to the second embodiment will be described using FIG. As described above, the difference between the second embodiment and the first embodiment is a reference for the base station management unit 203 to select a base station to be moved. In the second embodiment also, the upper limit value of the number of mobile terminals connected to each base station is 3.

  In the second embodiment, since the operation of the server 101 shown in FIG. 6 is different from that of the first embodiment in step 604, the operation in step 604 will be mainly described.

  As in the first embodiment, in step 603, the base station management unit 203 has the number of connected base stations A102 stored in the base station management table 202 shown in FIG. Is considered crowded. Next, the base station management unit 203 moves the base station B103 or the base station C104 that has not reached the upper limit value and moves one of the base stations B103 and C104 to a position that complements the communication range of the base station A102. A station is selected (step 604).

  In the second embodiment, the base station selection criterion for moving the position of the base station is used. From the base station management table 202, the base station management unit 203 refers to the location information of the congested base station A102 and the location information of the base stations B103 and C104 whose number of connections has not reached the upper limit. The base station management unit 203 then moves the base station B103, which is the base station closest to the base station A102, from the base station B103 and the base station C104 to a position that complements the communication range of the base station A102. select. The base station management unit 203 transmits movement instruction information for approaching the base station A102 to the selected base station B103 via the communication I / F 201 (step 605), and returns to step 601. As in the first embodiment, the movement instruction information includes a base station ID, base station position information, and the like.

  FIG. 9 is a block diagram showing the base station after movement according to Embodiment 2 of the present invention.

  As shown in FIG. 9, the base station B103 that has received the movement instruction from the server 101 moves to the vicinity of the base station A102 (position of x = 15), and keeps the mobile terminal 108 to which it is connected within the communication range. In addition, the mobile station waits for a connection request from the mobile terminal with a range that overlaps a part of the communication range of the base station A102 where the mobile terminals are concentrated as a new communication range.

  According to the communication system of the second embodiment, in a communication system in which mobile terminals move randomly, the communication capacity in a range where the mobile terminals are concentrated can be increased, and the mobile terminals can continue stable communication. Become.

  Furthermore, according to the communication system of the second embodiment, since a base station that is located closer to a congested base station is selected as a base station to move, the communication capacity in a range where mobile terminals are concentrated Can be increased more quickly.

(Embodiment 3)
In the first and second embodiments, the server has a base station management unit, and the base station management unit manages the base station using the number of connected mobile terminals of each base station. Is a case where any one of the base stations includes a base station management unit, and the base station management unit manages the base station using a flag indicating the connection state of the mobile terminal of each base station.

  Hereinafter, the communication system according to the third embodiment will be described with reference to FIGS. 10 to 15.

  FIG. 10 is a block diagram showing a configuration of a communication system according to the third embodiment.

  The difference between FIG. 10 and FIG. 1 according to Embodiment 1 is the presence or absence of a server. In FIG. 10, a base station A102, a base station B103, a base station C104, and an external network 100 are connected to each other. Note that the base station A102, the base station B103, the base station C104, and the external network 100 may be connected to each other by wired communication or may be connected to each other by wireless communication. In FIG. 10, a base station A102, a base station B103, a base station C104, and an external network 100 are interconnected by wired communication.

  FIG. 11 is a block diagram showing a configuration of a base station including a base station management unit according to the third embodiment.

  11, the base station according to the present embodiment includes a communication I / F 301, a CPU 302, a number management unit 303, a position movement control unit 304, a movement unit 305, a base station management unit 1106, and a base station management table 1107. In FIG. 11, the same reference numerals are given to the components included in the base stations in Embodiment 1 and Embodiment 2, and description thereof is omitted.

  The base station management unit 1106 performs reception of the connection state of the mobile terminal from the base station, discovery of a base station in which the number of connected mobile terminals has reached the upper limit, and base station arrangement management. The base station management table 1107 stores connection states of mobile terminals of base stations to be managed. Further, the base station having the configuration shown in FIG. 11 also manages its own station.

  In the third embodiment, in the configuration of the communication system according to FIG. 10, base station B103 is a base station having the configuration shown in FIG. 11, and base station A102 and base station C104 are the configurations shown in FIG. Suppose that the base station comprises The base station B103 manages three base stations, the base station A102, the base station B103, and the base station C104. Hereinafter, in the third embodiment, a base station that manages a plurality of base stations is referred to as a management base station.

  FIG. 12 shows an example of the base station management table according to the third embodiment.

  The difference between FIG. 12 and FIG. 4 according to Embodiment 1 is information regarding the connection state of the mobile terminal of each base station stored in the base station management table. The base station management table 1107 includes a base station ID that can be uniquely identified by each base station received by the base station management unit 1106, a connection number upper limit arrival flag received from the corresponding base station, and position information of each base station. Is stored. The connected number upper limit reach flag indicates that the number of connected mobile terminals to the base station has reached the upper limit. In this embodiment, the number of connected base stations reaches 1 from the base station that has reached the upper limit. However, it is assumed that 0 is transmitted from the base station that has not reached.

  In the third embodiment, if the upper limit value of the number of mobile terminals connected to each base station is 3, in the case of the communication system shown in FIG. 10, the base station management table 1107 has a base station A102 whose base station ID is A. 1 as a connection number upper limit reach flag of the base station ID B, 0 as a connection number upper limit reach flag of the base station B103 whose base station ID is B, 0 as a connection number upper limit reach flag of the base station C104 whose base station ID is C, Each is stored. Further, in the configuration of the communication system shown in FIG. 10, with reference to a certain coordinate reference point x = 0, the base station A102 is at the position x = 10, the base station B103 is at the position x = 20, and the base station C104 is x = 30, respectively. Therefore, the base station management table 1107 stores 10 as the location information of the base station ID A, 20 as the location information of the base station ID B, and 30 as the location information of the base station ID C. .

  Hereinafter, the operation of the base station according to Embodiment 3 will be described using FIG.

  FIG. 13 is a flowchart showing an operation of the base station according to Embodiment 3 of the present invention.

  The operation shown in the flowchart of FIG. 13 is performed not only by the base station A102 and the base station C104 but also by the base station B103, which is a management base station. Also, in FIG. 13, the same processes as those in FIG. 5, which is a flowchart showing the operation of the base station in the first embodiment, are given the same numbers, and description thereof is omitted.

  When the communication I / F 301 receives a connection request or a disconnection request from a mobile terminal, the communication I / F 301 outputs the request to the number management unit 303. The number management unit 303 performs predetermined processing, and increases or decreases the counter C indicating the number of connected mobile terminals (from step 502 to step 505 and from step 507 to step 509). The number management unit 303 determines whether the counter C has reached the upper limit of the number of connected mobile terminals (step 1311). If it is determined in step 1311 that the counter C has reached the upper limit value, the number management unit 303 sets the connected number upper limit value arrival flag to 1 (step 1312). On the other hand, if it is determined in step 1311 that the counter C has not reached the upper limit value, the number management unit 303 sets the connected number upper limit value arrival flag to 0 (step 1313). The number management unit 303 notifies the management base station of the updated connection number upper limit arrival flag via the communication I / F 301 (step 1314), and returns to step 502.

  Next, the operation of base station management section 1106 of the management base station according to Embodiment 3 will be described using FIG.

  FIG. 14 is a flowchart showing an operation of the management base station according to Embodiment 3 of the present invention.

  The communication I / F 301 determines whether or not the connected number upper limit arrival flag has been notified from the number management unit 303 of the base station A102, the base station C104, and the base station B103 that is the management base station (that is, the own station) ( Step 1401). If the communication I / F 301 determines in step 1401 that there is no notification of the connection number upper limit arrival flag from any of the base station A102, base station B103, and base station C104, the communication I / F 301 outputs the received packet to the CPU 302. The CPU 302 performs another process according to the received packet (step 606) and returns to step 1401.

  On the other hand, when there is a notification of the connection number upper limit arrival flag from any one of the base station A 102, the base station B 103, and the base station C 104, the communication I / F 301 outputs to the base station management unit 1106. The base station management unit 1106 updates the base station management table 1107 based on the notification from the base station (step 1402). Next, the base station management unit 1106 refers to the base station management table 1107 and determines whether or not the connected number upper limit arrival flag of any base station is 1 (step 1403). In step 1403, when the base station management unit 1106 determines that the connected number upper limit reach flag of all base stations is 0, the base station management unit 1106 returns to step 1401. In step 1403, when the base station management unit 1106 determines that there is a base station with the connected number upper limit reaching flag being 1, one base station is selected from the base stations with the connected number upper limit reaching flag being 0. Select (step 1404). In the third embodiment, since the base station management table 1107 is in the state shown in FIG. 12, the base station management unit 1106 has a communication range of the base station A102 in which the connection number upper limit arrival flag of the base station A102 is 1. Is considered crowded. The base station management unit 1106 moves one of the base station B103 and the base station C104 whose connected number upper limit value arrival flag is 0 to a position that overlaps a part of the communication range of the base station A102 and supplements the communication range. Select the base station to be used.

  In the third embodiment, as in the second embodiment, “the base station closest to the congested base station among the non-congested base stations” is used as a selection criterion for the base station to be moved. From the base station management table 1107, the base station management unit 1106 receives the position information of the base station A102 whose connected number upper limit reach flag is 1, and the base station B103 and base station C104 whose connected number upper limit reach flag is 0, respectively. Refer to the location information. Then, the base station management unit 1106 selects the base station B103, which is the terminal closest to the base station A102, from the base station B103 and the base station C104 as a base station that moves to a position that complements the communication range of the base station A102. To do. The base station management unit 1106 transmits movement instruction information for approaching the base station A102 to the selected base station B103 via the communication I / F 301 (step 1405), and returns to step 1401.

  In the third embodiment, base station B103 includes base station management section 1106, and the transmission destination of the movement instruction information is the own station. The base station management unit 1106 of the base station B 103 transmits movement instruction information to the position movement control unit 304 of its own station via the communication I / F 301. The position movement control unit 304 of the base station B103 receives the movement instruction information, calculates a control amount for moving to the instructed location, notifies the movement unit 305, and the movement unit 305 operates the movement mechanism.

  FIG. 15 is a block diagram showing the position of the base station after the base station B 103 has moved according to the third embodiment. The base station B103 selected as the base station to move itself moves to the vicinity of the base station A102, includes the mobile terminal 108 to which the base station B103 is connected in the communication range, and the base station A102 in which the mobile terminals are concentrated. A connection request from the mobile terminal is awaited by setting a range overlapping with a part of the communication range as a new communication range.

  As described above, according to the communication system of the third embodiment, by providing any base station with the function of managing the base station, the communication capacity in a range where mobile terminals are concentrated without a server. Can be increased more quickly.

  In the third embodiment, the management base station transmits a movement instruction to itself. Of course, depending on the selection result of the base station to be moved, the management base station issues a movement instruction to another base station. Also good.

  In the third embodiment, the base station including the base station management unit is the base station B103. However, the base station A102 and the base station C104 may include the base station management unit, or three base stations. Of these, two base stations or all base stations may include a base station management unit. However, there is only one base station in the system that causes the base station management unit to function and actually manages a plurality of base stations.

  In the third embodiment, the connection number upper limit reaching flag is used as the connection status of each base station. However, the present invention is not limited to this, and each base station stores the current number of connections, The base station management unit may determine whether the number of connected devices has reached the upper limit. At this time, the base station selection criterion to be moved may be the position of the base station, for example, “the base station closest to the congested base station among the non-congested base stations” or the number of connected mobile terminals, for example, “ A base station with the smallest number of connected mobile terminals may be used.

  Further, in the second embodiment, the connection status is managed using the number of connected units. However, each base station notifies the server of the connected number upper limit reaching flag, and the server uses the connected number upper limit reached flag, It may be determined whether the base station is congested.

(Embodiment 4)
In the first to third embodiments, the server or any one of the base stations includes the base station management unit and manages the base station. In the fourth embodiment, a case will be described in which all base stations are provided with a base station dispersion management unit, and each base station manages the connection status and position movement of each base station including its own station.

  The configuration of the communication system in the present embodiment is the same as that in the third embodiment shown in FIG.

  FIG. 16 is a block diagram showing a configuration example of a base station according to Embodiment 4 of the present invention.

  Base station A102, base station B103, and base station C104 according to Embodiment 4 are communication I / F 301, CPU 302, number management unit 1603, position movement control unit 1604, movement unit 305, base station dispersion management unit 1606, base station A station distribution management table 1607 is provided. Constituent elements similar to those of the base station of the first embodiment are given the same reference numerals and description thereof is omitted.

  The number management unit 1603 manages the number of connected mobile terminals of its own station, and notifies the base station dispersion management unit 1606 when the number of connected terminals changes. The position movement control unit 1604 receives movement instruction information from the base station dispersion management unit 1606 of the own station or another station, calculates a control amount for moving to the instructed location, and notifies the movement unit 305 of it. The base station dispersion management unit 1606 manages the connection state of the mobile terminal of the own station, notification of reaching the upper limit of the number of connected terminals with other stations, movement instructions, transmission / reception of a movable notification, selection of a base station to be moved, arrangement of base stations It is for management. The base station distribution management table 1607 stores the state of each base station.

  FIG. 17 is a diagram showing an example of the base station distribution management table according to the fourth embodiment.

  As shown in FIG. 17, the base station distribution management table 1607 stores a base station ID that can uniquely identify each base station, position information that indicates the current position of the base station, and a moveable notification flag. The movement notification flag is 1 for the base station that has transmitted the movement notification and 0 for the base station that has not transmitted the movement notification in response to the notification of reaching the upper limit of the number of connections from the own station. Is stored. In addition, since the local station does not respond to the notification of reaching the upper limit number of connected stations of the local station, 0 indicating the base station that cannot move is stored in the local mobility flag. In FIG. 17, since the own station is a base station whose base station ID is A, 0 is stored in the mobility notification flag.

  Hereinafter, the operation of the present embodiment will be described with reference to the drawings.

  First, the movement request process of the base station according to the fourth embodiment will be described.

  FIG. 18 is a flowchart showing movement request processing of the base station according to Embodiment 4 of the present invention.

  In FIG. 18, the same operations as those in FIG.

  When the communication I / F 301 receives a connection request or a disconnection request from a mobile terminal, the communication I / F 301 outputs the request to the number management unit 1603. The number management unit 1603 performs predetermined processing, and increases or decreases the counter C indicating the number of connected mobile terminals (from step 502 to step 505 and from step 507 to step 509). The number management unit 1603 determines whether the counter C has reached the upper limit value of the number of connected mobile terminals (step 1810). If it is determined in step 1810 that the counter C has reached the upper limit value, the number management unit 1603 notifies the base station distribution management unit 1606. Upon receiving the notification from the number management unit 1603, the base station distribution management unit 1606 notifies other base stations that the number of connected mobile terminals has reached the upper limit value via the communication I / F 301 (step 1811). The base station distribution management unit 1606 resets the timer value Timer to 0 (step 1812), and then returns to step 502. On the other hand, if it is determined in step 1810 that the counter C has not reached the upper limit value, the number management unit 1603 notifies the base station distribution management unit 1606 that the counter C has not reached the upper limit value. Return.

  In step 507, if the received packet is not a disconnection request from the mobile terminal, that is, if it is neither a connection request nor a disconnection request, the communication I / F 301 notifies that the received packet has reached the upper limit value transmitted by the local station. It is determined whether or not the response is from another station (step 1813). If the communication I / F 301 determines in step 1813 that a response from another station has been received, the communication I / F 301 outputs a response from the other station to the base station distribution management unit 1606. The base station distribution management unit 1606 stores the content of the response from the other station in the base station distribution management table 1607. The base station distribution management unit 1606 stores 0 in the item of the movement notification of the base station that has received the movement notification in the base station distribution management table 1607. Next, the base station distribution management unit 1606 determines whether or not the current Timer value is greater than a predetermined time x (> 0) (step 1814). When the Timer value is larger than the time x (when a predetermined time has elapsed), the base station dispersion management unit 1606 selects the base station to be moved using the base station dispersion management table 1607 (step 1815).

  If it is determined in step 1814 that the Timer value is greater than the time x, the base station dispersion management unit 1606 moves the base station to be moved to the moveable notification flag in the base station dispersion management table 1607 or the number of connected mobile terminals, Alternatively, the selection is made based on the location information of the base station or a combination thereof. The base station distribution management table 1607 in FIG. 17 does not store the number of connected mobile terminals of each base station, but may store the number of connected terminals. Each time the number management unit 1603 of each base station counts, the number of mobile terminals connected is notified to base stations other than its own station, and the base station distribution management table 1607 is updated.

  The base station distribution management unit 1606 notifies the base station selected in Step 1815 to move toward the base station (that is, the own station) that transmitted the upper limit arrival notification via the communication I / F 301 (Step S15). 1816), the process returns to Step 502.

  On the other hand, if the Timer value is less than the predetermined time x in step 1814, or if the received packet data is not a connection request, a disconnection request, or a response to the upper limit arrival notification, another processing for the received packet is performed by the CPU 302. If it has been performed, the base station distribution management unit 1606 increments the timer value Timer by 1 (step 1817) and returns to step 502.

  Next, the mobile response process of the base station according to the fourth embodiment will be described.

  FIG. 19 is a flowchart showing the mobile response processing of the base station according to Embodiment 4 of the present invention.

  The communication I / F 301 determines whether there is an upper limit arrival notification from another base station (step 1901). If the communication I / F 301 determines in step 1901 that an upper limit arrival notification has been received, the communication I / F 301 notifies the base station distribution management unit 1606 that an upper limit arrival notification has been received from another base station. The base station dispersion management unit 1606 inquires of the number management unit 1603 about the counter C indicating the number of connected mobile terminals to the own station, and determines whether the number of connected mobile stations has reached the upper limit (step 1902). . In step 1902, the base station distribution management unit 1606 returns to step 1901 if it determines that the number of connections to its own station has reached the upper limit value, and if it determines that it has not reached the communication I / F 301. The other base stations are notified of the fact that they can move (step 1903).

  If there is no upper limit arrival notification from another base station in step 1901, the communication I / F 301 determines whether or not a movement instruction has been received from another base station (step 1904). When it is determined that there has been a movement instruction notification, the communication I / F 301 outputs to the position movement control unit 1604, and the position movement control unit 1604 controls the movement unit 305 in accordance with the movement instruction notification (step 1905). Return to step 1901. If it is determined in step 1904 that there is no movement instruction notification, the CPU 302 performs another process corresponding to the received packet (step 510), and returns to step 1901.

  Hereinafter, the above operation will be described with reference to FIG. 20, taking the communication system of FIG. 10 as an example.

  FIG. 20 is a time chart showing the operation of each base station according to Embodiment 4 of the present invention. In the fourth embodiment, the upper limit value of the number of connected terminals is 3.

  In the case of FIG. 10, since the number of connected terminals of the base station A102 has reached the upper limit value of 3 (step 2001), the base station A102 notifies the base station B103 and the base station C104, respectively, an upper limit value arrival notification 2002, 2003 is transmitted. The base station B103 and the base station C104 receive the upper limit arrival notification from the base station A102, and check whether the number of connected mobile terminals of the own station has reached the upper limit (step 2004). In this case, since neither the base station B103 nor the base station C104 has reached the upper limit value, the mobile station notifies the base station A102 of the mobility notifications 2005 and 2006, respectively.

  When the predetermined time x elapses, the base station A102 selects either the base station B103 or the base station C104 that is the transmission source of the mobility notification received within that time as a mobile station (step 2007). In this case, the base station A102 selects the base station B103 and notifies the base station B103 of the movement instruction notification 2008. Upon receiving the movement instruction notification 2008, the base station B103 moves in accordance with the movement instruction notification 2008 (step 2009). A block diagram showing the position of the base station after the base station B103 has moved is shown in FIG.

  In this embodiment, each base station controls the moving unit 305 when there is a movement instruction notification. However, when the own station is movable and another base station has not responded. May move without waiting for notification of a movement instruction.

  The operation in this case will be described with reference to FIGS.

  FIG. 21 is a diagram showing another base station distribution management table according to the fourth embodiment.

  The difference between the base station distribution management table shown in FIG. 21 and FIG. 17 is the presence / absence of a mobility notification flag.

  FIG. 22 is a flowchart showing another movement request process of the base station according to the fourth embodiment. In FIG. 22, the same operations as those in FIG. 18 are denoted by the same reference numerals and description thereof is omitted.

  In the movement request process shown in FIG. 22, since the moving base station moves without waiting for the notification of the movement instruction, the base station that has made the movement request does not select the base station to be moved. For this reason, after transmitting the upper limit arrival notification to another base station in step 1811, the base station distribution management unit 1606 returns to step 502. If the packet received in step 502 and step 507 is neither a connection request nor a disconnection request, the communication I / F 301 outputs to the CPU 302 and performs another process corresponding to the packet received by the CPU 302 (step 510). Return to step 502.

  FIG. 23 is a flowchart showing another mobile response process of the base station according to Embodiment 4 of the present invention. In FIG. 23, the same operations as those in FIG.

  When there is an upper limit arrival notification from another base station, the communication I / F 301 notifies the base station distribution management unit 1606 that the upper limit arrival notification has been received from the other base station (step 1901). The base station dispersion management unit 1606 inquires of the number management unit 1603 about a counter C indicating the number of mobile terminals connected to the own station, and determines whether the number of connections to the own station has reached the upper limit (step 1902). ). If the base station distribution management unit 1606 determines in step 1902 that the number of connected mobile terminals of the local station has reached the upper limit value, it returns to step 1901 without doing anything.

  On the other hand, if the base station distribution management unit 1606 determines in step 1902 that the number of connected mobile terminals of the local station has not reached the upper limit value, it determines whether or not a mobility notification has been received from another base station. (Step 2303). In Step 2303, if the base station distribution management unit 1606 determines that a movement enable notification has been received from another base station, it returns to Step 1901 without doing anything.

  If the base station distribution management unit 1606 determines in step 2303 that it has not received a movement notification from another base station, the base station distribution management unit 1606 selects the base station to move the base station through the communication I / F 301. It notifies other base stations that it can move (step 2304). The base station distribution management unit 1606 refers to the base station distribution management table 1607 to determine the position of the movement destination, creates position information indicating the determined position, and outputs the position information to the position movement control unit 1604. The position movement control unit 1604 controls the moving unit 305 to move the position of the own station so as to overlap with a part of the communication range of the base station that has notified the upper limit arrival notification (step 2305).

  Hereinafter, the above operation will be described with reference to FIG. 24 taking the communication system of FIG. 10 as an example. In FIG. 24, the same operations as those in FIG.

  The base station B103 that has received the upper limit arrival notification 2002 from the base station A102 determines whether or not it can move. (Step 2004). The base station B103 determines that it can move, notifies the base station A102 and the base station C104 of a movement availability notification 2405, and then moves to approach the base station A102 (step 2406).

  In step 1814 in the present embodiment, the base station to be moved is selected when the Timer value exceeds the predetermined value x. However, the base station moves first without waiting for the Timer value to exceed the predetermined value x. The station that has notified the possible notification may be selected.

  In addition, when each base station reaches the upper limit value of the number of connected mobile terminals, it sends an upper limit value notification to other base stations, but notifies each other base station each time the number of connected terminals increases or decreases. However, another base station may determine that the upper limit has been reached.

  In each embodiment, the selection criterion for the base station to be moved is the number of connected mobile terminals or the position of the base station. However, a selection criterion combining these two may be used. In each of the embodiments, the base station with the fewest number of connections or the closest base station is selected based on this selection criterion. Among the base stations to be selected, the base station with the smaller number of connections or the connection is selected. You may select from the base stations in the position close | similar to the base station in which the number reached the upper limit.

  The present invention is useful in a radio communication system in which a plurality of base stations and a plurality of radio terminals exist in a relatively wide space.

100 External network 101 Server 102, 103, 104 Base station 105, 106, 107, 108 Mobile terminal 201, 301 Communication I / F
202, 1107 Base station management table 203, 1106 Base station management unit 204, 302 CPU
303, 1603 Number management unit 304, 1604 Position movement control unit 305 Movement unit 1606 Base station distribution management unit 1607 Base station distribution management table

Claims (23)

A communication system comprising a plurality of mobile terminals and a plurality of base stations,
A base station management unit for managing the arrangement of the plurality of base stations;
The plurality of base stations are movable;
The base station management unit determines, for each base station, whether or not the number of connected mobile terminals has reached a predetermined upper limit value,
When there is a base station that has reached the upper limit value, one base station is selected from the base stations that have not reached the upper limit value, and the communication range of the selected base station is selected as the selected base station. A wireless communication system that moves so as to overlap a part of a communication range of a base station that has reached the upper limit value. When each base station makes a wireless connection with the mobile terminal, it transmits the current number of connections to the base station management unit,
2. The base station management unit manages the number of connections transmitted from each base station, and determines whether the number of connections of each base station has reached the upper limit value using the number of connections. Wireless communication system. When each base station has made a wireless connection with the mobile terminal or has disconnected a wireless connection with the mobile terminal, the base station indicates a connection state indicating a wireless connection with the mobile terminal or a disconnection of the wireless connection with the base station. To the station management department,
The base station management unit manages the number of connected base stations according to the connection state transmitted from each base station, and uses the number of connected, the number of connected base stations reaches the upper limit value. The wireless communication system according to claim 1, wherein it is determined whether or not there is. Each base station, when performing a wireless connection with the mobile terminal, transmits a connection state indicating whether or not the current number of connections has reached the upper limit value to the base station management unit,
The said base station management part manages the connection state transmitted from the said base station, and determines whether the connection number of each base station has reached the said upper limit using the said connection state. Wireless communication system.   4. The wireless communication system according to claim 2, wherein the base station management unit selects a base station with a small number of connected units among base stations that have not reached the upper limit value. 5.   6. The radio according to claim 2, wherein the base station management unit selects a base station located near a base station that has reached the upper limit value among base stations that have not reached the upper limit value. Communications system. With a server,
The wireless communication system according to claim 1, wherein the server includes a base station management unit.   The wireless communication system according to claim 1, wherein at least one base station of the plurality of base stations includes the base station management unit. Each base station includes the base station management unit,
A unit management unit for managing the number of connected mobile terminals,
If the number management unit determines that the current number of connected devices has reached the upper limit value, it transmits a connection number upper limit arrival notification indicating that the number of connected devices has reached the upper limit value to another base station,
When the base station management unit receives the connection number upper limit arrival notification, the base station management unit checks its own number of connections, and if the number of connections does not reach the upper limit value, it indicates that the upper limit value has not been reached. Send notifications to other base stations,
If the upper limit value has been reached, one base station is selected from the base stations from which the received movable notification is transmitted, and the communication range of the selected base station is the communication range of the selected base station. The wireless communication system according to claim 1, wherein the wireless communication system is moved so as to overlap a part of the range.   The wireless communication system according to claim 9, wherein the base station management unit selects a base station that is a transmission source of the first received mobility notification in the selection.   The wireless communication system according to claim 9, wherein, in the selection, the base station management unit selects a base station that is in a position close to itself among base stations from which the movable notification is transmitted. The moveable notification includes the current number of connections,
The wireless communication system according to claim 9 and 11, wherein the base station management unit selects a base station with a small number of connections among base stations from which the mobility notification is transmitted in the selection. Each base station includes the base station management unit,
A unit management unit for managing the number of connected mobile terminals,
If the number management unit determines that the current number of connected devices has reached the upper limit value, it transmits a connection number upper limit arrival notification indicating that the number of connected devices has reached the upper limit value to another base station,
When the base station management unit receives the connection number upper limit arrival notification, the base station management unit checks its own number of connections, and if the number of connections does not reach the upper limit, selects the base station to move itself, A movement possible notification indicating that the value has not been reached is transmitted to another base station, and the communication range of the base station that has transmitted the connection number upper limit arrival notification is moved so that a part of its communication range overlaps. The wireless communication system according to claim 1. A base station management method for managing arrangement of base stations in a communication system including a plurality of mobile terminals and a plurality of base stations,
The plurality of base stations are movable;
The base station management unit that manages the arrangement of the plurality of base stations determines, for each base station, whether or not the number of connected mobile terminals has reached a predetermined upper limit value,
When there is a base station that has reached the upper limit value, one base station is selected from the base stations that have not reached the upper limit value, and the communication range of the selected base station is selected as the selected base station. A management method of a base station that moves so as to overlap a part of the communication range of the base station that has reached the upper limit value. When each base station makes a wireless connection with the mobile terminal, it transmits the current number of connections to the base station management unit,
The said base station management part manages the number of connections transmitted from each said base station, and determines whether the number of connections of each base station has reached the said upper limit using the said number of connections. Base station management method. When each base station has made a wireless connection with the mobile terminal or has disconnected a wireless connection with the mobile terminal, the base station indicates a connection state indicating a wireless connection with the mobile terminal or a disconnection of the wireless connection with the base station. To the station management department,
The base station management unit manages the number of connected base stations according to the connection state transmitted from each base station, and uses the number of connected, the number of connected base stations reaches the upper limit value. The base station management method according to claim 14, wherein it is determined whether or not there is any. Each base station, when performing a wireless connection with the mobile terminal, transmits a connection state indicating whether or not the current number of connections has reached the upper limit value to the base station management unit,
The said base station management part manages the connection state transmitted from the said base station, and determines whether the connection number of each base station has reached the said upper limit using the said connection state. Base station management method.   The base station management method according to claim 15 or 16, wherein the base station management unit selects a base station with a small number of connected units among base stations that have not reached the upper limit value.   The base station according to any one of claims 15 to 18, wherein the base station management unit selects a base station located near a base station that has reached the upper limit value among base stations that have not reached the upper limit value. Station management method. Each base station includes the base station management unit,
A unit management unit for managing the number of connected mobile terminals,
If the number management unit determines that the current number of connected devices has reached the upper limit value, it transmits a connection number upper limit arrival notification indicating that the number of connected devices has reached the upper limit value to another base station,
When the base station management unit receives the connection number upper limit arrival notification, the base station management unit checks its own number of connections, and if the number of connections does not reach the upper limit value, it indicates that the upper limit value has not been reached. Send notifications to other base stations,
If the upper limit value has been reached, one base station is selected from the base stations from which the received movable notification is transmitted, and the communication range of the selected base station is the communication range of the selected base station. The base station management method according to claim 14, wherein the base station is moved so as to overlap a part of the range.   21. The base station management method according to claim 20, wherein, in the selection, the base station management unit selects a base station that is a transmission source of the first received mobility notification.   The base station management method according to claim 20, wherein, in the selection, the base station management unit selects a base station in a position close to itself among base stations from which the movable notification is transmitted. The moveable notification includes the current number of connections,
The base station management method according to claim 21 and 22, wherein, in the selection, the base station management unit selects a base station with a small number of connections among base stations from which the movable notification is transmitted.