JP2015088782A - Radio communication system, control method for radio communication system, program, and radio base station device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To complete AP changeover by a terminal in a shorter period of time without using a communication management device.SOLUTION: A radio communication system 40 includes a radio base station device 11 and a radio base station device 12. The radio base station device 11 comprises: a radio communication unit 111 capable of performing radio communication on a first communication path identified by a first channel and BSSID; an establishment unit 112 for establishing a first communication link with a terminal by generating control information by authentication and connection establishment; an information transmission unit for transmitting taking-over information including the control information to the radio base station device 12; and a changeover transmission unit 115 for transmitting a changeover notification frame for including a fact that a radio communication channel used by the terminal is to be changed to a second channel differing from the first channel by a DFS function. The second base station device 12 comprises: a radio communication unit 121 capable of performing radio communication on a second communication path identified by the second channel and BSSID; and an establishment unit 122 for establishing a second communication link with the terminal after receiving the changeover notification frame, by using the taking-over information.

Description

  The present invention relates to a radio communication system, a radio communication system control method, a program, and a radio base station apparatus.

  Conventionally, a WLAN (Wireless Local Area Network) using a wireless communication terminal and a wireless base station apparatus (hereinafter also referred to as an access point or AP (Access Point)) that communicates with the wireless communication terminal via a wireless link has been used. Has been. The wireless communication terminal can communicate with other communication devices (such as a Web server or a mail server) on the network connected to the WLAN via the WLAN.

  An area (hereinafter referred to as a wireless communicable area) in which one wireless base station apparatus can communicate via a wireless communication link (hereinafter also referred to as a communication link) is limited. When a wireless communication terminal is used in a wide space that cannot be covered by only one wireless base station device, a plurality of wireless base station devices are installed. At that time, the wireless communication terminal establishes a communication link with any one of the wireless base station devices. When communication via the communication link cannot be performed for some reason and the wireless communication terminal can establish a communication link with another wireless base station device, the wireless communication terminal Communication can be continued (AP switching) by establishing a communication link with the station apparatus.

  Patent Document 1 discloses a wireless communication system capable of handover (AP switching) by a wireless communication terminal. According to the technique disclosed in Patent Literature 1, when an AP is switched by a radio communication terminal, the radio base station apparatus to which the AP is switched is a radio having the same BSSID as the radio base station apparatus to which the radio communication terminal is connected. Changed to provide communication. The wireless communication terminal can perform AP switching to a wireless base station device having the same BSSID as the connected wireless base station device.

JP 2010-178175 A

  However, in the wireless communication system disclosed in Patent Literature 1, the communication management device in the wireless communication system monitors the communication quality of wireless communication by each wireless communication terminal, and the wireless base station device to which each wireless communication terminal should be connected By determining, AP switching by the communication terminal is realized in a short time. That is, in the above communication system, a communication management device is essential.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a wireless communication system that completes AP switching by a communication terminal in a short time without using a communication management device.

  In order to solve the above problems, a wireless communication system according to an aspect of the present invention includes a first wireless base station, and a second wireless base station connected to the first wireless base station via a network. The first radio base station can perform radio communication with a communication terminal on a first communication path specified by a first frequency channel and a BSSID (Basic Service Set Indentifier). And a first establishment unit for establishing a first communication link with the communication terminal by generating control information necessary for wireless communication with the communication terminal via the first wireless communication unit through authentication and connection establishment. An information transmission unit that transmits handover information including the control information to the second radio base station, and a frequency channel of radio communication by the communication terminal is set to the first frequency A switching transmission unit for transmitting a switching notification frame including a change to a second frequency channel different from the channel by a DFS (Dynamic Frequency Selection) function to the communication terminal via the first wireless communication unit, The second radio base station includes a second radio communication unit capable of performing radio communication with the communication terminal on a second communication path specified by the second frequency channel and the BSSID, and the first radio base. A second establishment unit that establishes a second communication link with the communication terminal after receiving the switching notification frame using the handover information received from a station.

  According to this, the wireless communication system can cause the communication terminal to perform AP switching using the DFS function. Specifically, the radio communication system is configured such that the communication paths between the first radio base station and the second radio base station are different frequency channels and have the same BSSID. . And a communication terminal can be in the state which established the connection with the 2nd wireless base station by changing only a frequency channel by the DFS function from the state which established the connection with the 1st wireless base station. Since the channel change by the DFS function is used in this way, authentication, connection establishment, or communication path existence confirmation is performed when the communication terminal establishes a connection with the second radio base station after switching the frequency channel. The AP switching can be completed without any problem. In addition, the wireless communication system does not require a device or function corresponding to a communication management device that centrally manages the communication status of the wireless base station or the communication terminal, and is based on the function of the wireless base station and the communication terminal. Realized. Therefore, the wireless communication system can complete AP switching by the communication terminal in a shorter time without using the communication management device.

  In addition, the first radio base station further includes a determination unit that determines whether or not a condition determined from a state of radio communication by the communication terminal is satisfied after the first establishment unit generates the control information. The information transmission unit transmits the handover information when the determination unit determines that the condition is satisfied, and the switching transmission unit transmits the switching notification frame when the determination unit determines that the condition is satisfied. It may be transmitted.

  According to this, the wireless communication system can perform determination based on the state of wireless communication by the communication terminal, and can perform AP switching by the communication terminal based on the determination result.

  The determination unit may determine that the condition is satisfied when the first wireless communication unit detects that the received signal strength of the radio wave received from the communication terminal is less than a threshold value.

  According to this, the wireless communication system moves so that the communication terminal established with the first wireless base station moves away from the first wireless base station, or blocks the communication path between the first wireless base station and the communication terminal. If it is detected that the received signal strength received from the communication terminal by the first radio base station is less than the threshold, AP switching in the communication terminal can be performed. This is because, in this situation, it is considered that the wireless communication by the communication terminal is better when the AP is switched.

  The second wireless communication unit further detects a received signal strength of a radio wave received from the communication terminal, and the determination unit has a received signal strength detected by the second wireless communication unit equal to or greater than a threshold value. It may be determined that the condition is satisfied when the above is detected.

  According to this, the wireless communication system moves so that the communication terminal established with the first wireless base station approaches the second wireless base station, or exists in the communication path between the second wireless base station and the communication terminal. When it is detected that the received signal strength received by the second radio base station from the communication terminal is equal to or higher than the threshold value due to the disappearance of the obstructed object, AP switching by the communication terminal can be performed. . This is because, in this situation, it is considered that the wireless communication by the communication terminal is better when the AP is switched.

  The control information is used for encrypted wireless communication between the first wireless base station and the communication terminal and includes a dynamically generated shared key. The takeover information further includes the first information A sequence number to be described in a data frame used for wireless communication between the wireless base station and the communication terminal may be included.

  According to this, the communication terminal can continue the encrypted communication performed with the first radio base station before the AP switching with the second radio base station after the AP switching.

  The switching transmission unit includes a destination determination unit that determines a destination of the switching notification frame by the switching transmission unit, and the switching transmission unit sends the switching notification frame to the destination determined by the destination determination unit. Unicast transmission may be used.

  According to this, after determining the communication terminal that performs AP switching, the wireless communication system can cause only the determined communication terminal to perform AP switching. Thereby, for example, only the communication terminal that has moved away from the first radio base station or only the communication terminal that has a shield in the communication path with the first radio base station can perform AP switching.

  The switching transmission unit may broadcast the switching notification frame.

  According to this, the wireless communication system can cause all communication terminals established with the first wireless base station to perform AP switching. As a result, for example, when the first radio base station is stopped for some reason, the communication terminal established with the first radio base station can be switched to the second radio base station.

  The switching notification frame may be a CSA (Channel Switch Announcement) frame in the DFS function, and may be a CSA frame including the channel number of the second frequency channel as a switching destination channel number.

  According to this, the wireless communication system can perform AP switching using the CSA frame in the DFS function which is a general-purpose technology. That is, if the communication terminal is compatible with the DFS function, the above AP switching can be performed without implementing any other special function.

  In order to solve the above-described problem, a control method of a radio communication system according to an aspect of the present invention includes a first radio base station, a second radio base station connected to the first radio base station through a network, and The first wireless base station performs wireless communication with a communication terminal on a first communication path specified by a first frequency channel and a BSSID (Basic Service Set Indentifier). A second wireless base station capable of performing wireless communication with the communication terminal on a second communication path specified by the second frequency channel and the BSSID. A control method of the wireless communication system, comprising: a second wireless communication unit; control information necessary for wireless communication with the communication terminal via the first wireless communication unit A first establishment step of establishing a first communication link with the communication terminal by generating by authentication and connection establishment, an information transmission step of transmitting takeover information including the control information to the second radio base station, A switching notification frame including changing the frequency channel of the wireless communication by the communication terminal to a second frequency channel different from the first frequency channel by a DFS (Dynamic Frequency Selection) function is sent via the first wireless communication unit. A switching transmission step for transmitting to the communication terminal, and a second communication link with the communication terminal after receiving the switching notification frame using the takeover information received from the first radio base station. Establishing step.

  Thereby, there exists an effect similar to said radio | wireless communications system.

  In order to solve the above problem, a program according to an aspect of the present invention is a program for causing a computer to execute the above-described control method of the wireless communication system.

  Thereby, there exists an effect similar to said radio base station apparatus.

  In order to solve the above problems, a radio base station apparatus according to an aspect of the present invention includes the first radio base station or the second radio base station in the radio communication system described above.

  Thereby, there exists an effect similar to said radio base station apparatus.

  Note that the present invention can be realized not only as an apparatus but also as a method using steps as processing units constituting the apparatus, as a program for causing a computer to execute the steps, or as a computer read recording the program. It can also be realized as a possible recording medium such as a CD-ROM, or as information, data or a signal indicating the program. These programs, information, data, and signals may be distributed via a communication network such as the Internet.

  The wireless communication system according to the present invention can complete AP switching by a communication terminal in a short time without using a communication management device.

FIG. 1 is a network configuration diagram of a wireless communication system according to an embodiment. FIG. 2 is a hardware configuration diagram of the radio base station apparatus according to the embodiment. FIG. 3 is a functional block diagram of the radio base station apparatus according to the embodiment. FIG. 4A is an explanatory diagram of information included in the CSA frame according to the embodiment. FIG. 4B is an explanatory diagram of takeover information according to the embodiment. FIG. 5A is a flowchart of the first radio base station apparatus according to the embodiment. FIG. 5B is a flowchart of the second radio base station apparatus according to the embodiment. FIG. 6 is a flowchart of the communication terminal according to the embodiment. FIG. 7 is a sequence diagram showing communication by the wireless communication system according to the embodiment. FIG. 8 is an explanatory diagram of a first usage example of AP switching by the communication terminal according to the embodiment. FIG. 9 is an explanatory diagram of a second usage example of AP switching by the communication terminal according to the embodiment.

  Hereinafter, embodiments will be specifically described with reference to the drawings.

  Each of the embodiments described below shows a preferred specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connecting forms of the constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are described as optional constituent elements that constitute a more preferable embodiment.

  In addition, the same code | symbol is attached | subjected to the same component and description may be abbreviate | omitted.

(Embodiment)
In the present embodiment, a wireless communication system that completes AP switching by a communication terminal in a short time without using a communication management device will be described. Note that AP switching is performed, for example, at the time of handover when the wireless communication terminal moves away from the wireless base station device that has established the communication link and approaches another wireless base station device. In addition, when a wireless communication terminal existing in a communicable area of two wireless base station apparatuses establishes a communication link with one wireless base station apparatus, AP switching is also performed when the communication quality of the communication link deteriorates. Is done. In this case, a communication link can be established with the other radio base station apparatus by AP switching. Furthermore, AP switching is also performed when a radio base station apparatus with which a radio communication terminal has established a communication link stops due to a failure or when the radio base station apparatus is powered off by a maintenance person.

  In the present embodiment, AP switching is described assuming that it occurs due to handover, but the cause of AP switching in the present invention is not limited to handover.

  FIG. 1 is a network configuration diagram of a wireless communication system 40 according to the present embodiment.

  As shown in FIG. 1, the radio communication system 40 according to the present embodiment includes a radio base station apparatus 11, a radio base station apparatus 12, a LAN (Local Area Network) 31, and a communication terminal 35.

  The radio base station apparatus 11 is a radio base station apparatus having a radio communication interface, establishes a communication link 25 with a communication terminal 35 existing in a radio communicable area, and performs radio communication. The communication link 25 is established in a logical communication path 21 (hereinafter, also simply referred to as “communication path”) for wireless communication. The communication path is specified by attribute information including a frequency channel (hereinafter also simply referred to as “channel”) indicating the frequency of the radio wave used for wireless communication, and a BSSID (Basic Service Set Indentifier) that is a network identifier. The attribute information 21A of the communication path 21 of the radio base station apparatus 11 has a channel number (Ch) of 1 and a BSSID of aa. The BSSID is a numerical value expressed by 48 bits (a numerical value expressed by a 12-digit hexadecimal number) and may be expressed as “00: 00: 01: 00: 11: aa”. Note that the wireless communication is realized by a wireless LAN that conforms to, for example, the IEEE 802.11a, b, g, and n standards.

  Further, the radio base station apparatus 11 is connected to the LAN 31, and transfers the communication frame toward the destination according to the destination of the communication frame (communication packet) used for radio communication. Specifically, the radio base station apparatus 11 receives a communication frame addressed to a terminal on the LAN 31 side (a terminal connected to the LAN 31 or a terminal connected to a network connected to the LAN 31) from the communication terminal 35. Then, the communication frame is transferred to the LAN 31. Further, upon receiving a communication frame destined for the communication terminal 35 from the terminal on the LAN 31 side, the radio base station apparatus 11 transfers the communication frame to the communication terminal 35. The radio base station apparatus 11 corresponds to a first radio base station.

  Similar to the radio base station apparatus 11, the radio base station apparatus 12 is a radio base station apparatus having a radio communication interface. The radio base station apparatus 12 establishes a communication link 26 with the communication terminal 35 and performs radio communication. The attribute information 22A of the communication path 22 of the radio base station apparatus 12 has a channel number (Ch) of 36 and a BSSID of aa. That is, the communication path 21 of the radio base station apparatus 11 and the communication path 22 of the radio base station apparatus 12 have different channels and the same BSSID. The radio base station apparatus 12 corresponds to a second radio base station.

  The LAN 31 is a communication network (local area network) used for communication between the radio base station apparatus 11 and the radio base station apparatus 12. The LAN 31 is realized by, for example, a wired LAN conforming to the IEEE 802.3 standard.

  The communication terminal 35 is a wireless communication terminal having a wireless communication interface. The communication terminal 35 establishes a communication link 25 with the radio base station apparatus 11 or establishes a communication link 26 with the radio base station apparatus 12 to perform radio communication. The communication terminal 35 can communicate with the terminal on the LAN 31 side via the communication link 25 and the radio base station apparatus 11 or the communication link 25 and the radio base station apparatus 12.

  In the present embodiment, the communication terminal 35 establishes the communication link 25 with the radio base station apparatus 11 and then enters the state in which the communication link 26 is established with the radio base station apparatus 12 by handover. The process will be described. According to the wireless communication system according to the present embodiment, AP switching by a communication terminal can be completed in a short time without depending on the communication management device. Note that the radio base station apparatus that established the communication link before the communication terminal 35 is handed over is the handover source base station, and the radio base station apparatus that established the communication link after the communication terminal 35 is handed over is the handover destination base station. May be described.

  FIG. 2 is a hardware configuration diagram of radio base station apparatus 11 according to the present embodiment.

  As illustrated in FIG. 2, the radio base station apparatus 11 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a storage device 104, and a WNIC (Wireless). A network interface card (NIC) 105 and a network interface card (NIC) 106 are provided. Note that the radio base station apparatus 12 according to the present embodiment has the same hardware configuration as that of the radio base station apparatus 11.

  The CPU 101 is a processor that executes a control program stored in the ROM 102.

  The ROM 102 is a read-only storage area that holds a control program and the like.

  The RAM 103 is a volatile storage area used as a work area used when the CPU 101 executes a control program.

  The storage device 104 is a non-volatile storage area that holds a control program or image data.

  The WNIC 105 is a wireless communication interface that performs wireless communication with the communication terminal 35. The WNIC 105 is a wireless LAN communication interface that conforms to, for example, the IEEE 802.11a, b, g, and n standards.

  The NIC 106 is a communication interface that transmits communication data to the LAN 31 or receives communication data from the LAN 31. The NIC 106 may be a wired LAN interface that conforms to the IEEE 802.3 standard or the like, or may be a wireless LAN interface that conforms to the IEEE 802.11a, b, g, n standard, or the like. The NIC 106 may be realized using the WNIC 105.

  As described above, radio base station apparatus 12 according to the present embodiment has the same hardware configuration as radio base station apparatus 11, and thus detailed description of radio base station apparatus 12 will be omitted.

  FIG. 3 is a functional block diagram of radio base station apparatus 11 and radio base station apparatus 12 according to the present embodiment.

  As illustrated in FIG. 3, the radio base station apparatus 11 includes a radio communication unit 111, an establishment unit 112, a determination unit 113, an information transmission unit 114, and a switching transmission unit 115. In addition, the radio base station apparatus 12 includes a radio communication unit 121 and an establishment unit 122.

  The wireless communication unit 111 can perform wireless communication with the communication terminal 35 using the communication path 21. As described above, the communication path 21 has the channel 1 and the BSSID aa. The wireless communication unit 111 corresponds to the first wireless communication unit, the communication path 21 corresponds to the first communication path, and the channel of the communication path 21 corresponds to the first frequency channel. The wireless communication unit 111 is realized by the WNIC 105 or the like.

  The establishment unit 112 performs authentication and connection establishment with the communication terminal 35 via the wireless communication unit 111, thereby generating control information necessary for wireless communication with the communication terminal 35 and establishing the communication link 25. Specifically, the establishment unit 112 generates control information necessary for communication with the communication terminal 35 by performing authentication (Authentication) and connection establishment (Association) with the communication terminal 35. Specifically, the control information corresponds to IEEE 802.11 authentication information, and WPA (Wi-Fi Protected Access) or WPA2 key information (PMK (Pairwise Master Key)) used for encryption. . In addition, after the establishing unit 112 establishes the communication link 25, the state in which the communication link exists may be referred to as a “connection established state”.

  The determination unit 113 is a condition for switching the connection from the radio base station apparatus 11 to the radio base station apparatus 12 by the communication terminal 35 after the establishment unit 112 generates the control information (hereinafter also referred to as radio base station switching condition). Whether or not is satisfied is determined. The radio base station switching condition is that, when the communication terminal 35 is connected to the radio base station apparatus 11, higher quality or higher speed communication is achieved when the connection is established with the radio base station apparatus 12 than with the radio base station apparatus 11. This is a condition indicating that it can be performed. Note that the determination unit 113 is not an essential component of the present invention.

  The wireless base station switching condition is determined using, for example, the received signal strength of the radio wave received from the communication terminal 35 by the wireless communication unit 111. That is, the determination unit 113 monitors the received signal strength of the radio wave received by the wireless communication unit 111 from the communication terminal 35 after the establishment unit 112 generates the control information, and detects that the received signal strength is less than the threshold value. In this case, it is determined that the radio base station switching condition is satisfied. Further, the radio base station switching condition may be determined using the reception intensity of the radio wave received from the communication terminal 35 by the radio base station device 12. That is, the determination unit 113 determines that the wireless base station switching condition is satisfied when it is detected that the received signal strength of the radio wave from the communication terminal 35 received by the wireless communication unit 121 of the wireless base station device 12 is greater than or equal to the threshold value. You may do that. The radio base station apparatus 12 transmits the received signal strength to the radio base station apparatus 11 to determine whether or not the received signal intensity of the radio wave from the communication terminal 35 observed by the radio base station apparatus 12 is greater than or equal to the threshold value. After that, the radio base station apparatus 11 may perform it. Alternatively, the radio base station apparatus 12 that observes the received signal strength may perform the determination and notify the radio base station apparatus 11 of the determination result.

  The information transmission unit 114 transmits handover information including control information to the radio base station apparatus 12 when the determination unit 113 determines that the radio base station switching condition is satisfied. Inheritance information includes a sequence number in addition to control information. The takeover information will be described in detail later.

  When the determination unit 113 determines that the wireless base station switching condition is satisfied, the switching transmission unit 115 is a switching notification frame in the DFS (Dynamic Frequency Selection) function, and changes the frequency channel of the wireless communication by the communication terminal 35 to the wireless A switching notification frame including a change to the frequency channel of the communication path 22 of the base station apparatus 12 is transmitted via the wireless communication unit 111. The switching notification frame is realized by using a CSA (Channel Switch Announcement) frame. The transmission of the CSA frame may be unicast transmission that designates a destination terminal or may be broadcast transmission that has all terminals as destinations. An example of use when each of the above transmissions is used will be described in detail later.

  Each of the establishment unit 112, the determination unit 113, the information transmission unit 114, and the switching transmission unit 115 is realized by the CPU 101, the ROM 102, the RAM 103, the storage device 104, the WNIC 105, the NIC 106, or the like.

  The wireless communication unit 121 can perform wireless communication with the communication terminal 35 using the communication path 22. As described above, the communication path 22 has the channel 36 and the BSSID aa. The wireless communication unit 121 corresponds to the second wireless communication unit, the communication path 22 corresponds to the second communication path, and the channel of the communication path 22 corresponds to the second frequency channel. Further, the wireless communication unit 121 is realized by a WNIC or the like. Note that the wireless communication unit 121 is realized by a WNIC or the like.

  Using the takeover information received from the radio base station apparatus 11, the establishment unit 122 establishes a connection with the communication terminal 35 after receiving the switch notification frame, that is, establishes the communication link 26. The establishing unit 122 is realized by a CPU, ROM, RAM, storage device, WNIC, NIC, or the like.

  Here, a general description of the DFS function is shown. The DFS function is a communication path generally used for connection between a radio base station apparatus and a communication terminal in a communication system including a radio base station apparatus and a communication terminal established in connection with the radio base station apparatus. It is a function to change the channel. The DFS function is used, for example, when radio waves for different uses from information communication (for example, weather radar radio waves) and the information communication radio waves use the same frequency band. In this case, the radio base station apparatus monitors whether or not the radio wave transmitted by the weather radar is received. When a weather radar radio wave is detected, a CSA frame, which is a management frame including changing the channel of the communication path used for connection with the communication terminal, is transmitted to the communication terminal. Move. Specifically, the CSA frame includes a channel number of a channel newly used by the radio base station apparatus. The communication terminal that has received the CSA frame acquires the channel number included in the CSA frame, and changes the channel of its own communication path to the acquired channel number. When changing a channel, the communication terminal does not perform an operation such as authentication or connection establishment or reception of a beacon for confirming that a new communication path with the channel number exists, and uses a new channel. Start communication. The DFS function is defined, for example, in the IEEE 802.11h standard.

  FIG. 4A is an explanatory diagram of information included in the CSA frame 401 according to the present embodiment. A CSA frame 401 shown in FIG. 4A is an example of a CSA frame transmitted by the switching transmission unit 115 of the radio base station apparatus 11. The CSA frame 401 includes a switching destination channel number 411.

  In the switching destination channel number 411, the channel number of the communication path 22 of the radio base station apparatus 12 is written. In the network configuration (FIG. 1) in the present embodiment, “36” is written.

  FIG. 4B is an explanatory diagram of takeover information according to the present embodiment.

  As illustrated in FIG. 4B, the takeover information 421 includes control information 431 and a sequence number 432.

  In the control information 431, control information generated by the establishing unit 112 through authentication and connection establishment is written.

  In the sequence number 432, a serial number used for data communication with the communication terminal 35 is written. In general, a data frame in wireless communication is assigned a serial number that can identify the new and old (first and second) of the data frame. In the sequence number 432, the latest serial number in the radio base station apparatus 11 is written. Note that in IEEE 802.11, the above serial number corresponds to information written in the “sequence control” field.

  FIG. 5A is a flowchart of radio base station apparatus 11 according to the present embodiment. FIG. 5B is a flowchart of radio base station apparatus 12 according to the present embodiment. FIG. 6 is a flowchart of the communication terminal according to the present embodiment. FIG. 7 is a sequence diagram showing communication by the radio communication system according to the present embodiment. The operation of the wireless communication system 40 will be described with reference to these. In these drawings, the communication terminal is described as “STA”, and the radio base station apparatus is described as “AP”. The same description may be used in the subsequent figures.

  Processing of radio base station apparatus 11 according to the present embodiment will be described with reference to FIG. 5A.

  In step S500, the radio base station apparatus 11 acquires the attribute information 22A of the radio base station apparatus 12 from the radio base station apparatus 12 via the LAN 31. There are various methods for the radio base station apparatus 11 to acquire the attribute information 22A. For example, the radio base station apparatus 11 transmits a signal requesting the attribute information 22A to the radio base station apparatus 12, and the radio base station apparatus 11 transmits the attribute information 22A transmitted by the radio base station apparatus 12 according to the signal. There is a way to get. Alternatively, the radio base station apparatus 12 may spontaneously transmit the attribute information 22A to the radio base station apparatus 11, and the radio base station apparatus 11 may receive the transmitted attribute information 22A.

  In step S <b> 501, the establishment unit 112 generates control information through authentication (Authentication) and connection establishment (Association) with the communication terminal 35. The above authentication and connection establishment correspond to Authentication 701 and Association 702 in FIG. 7, respectively. When the authentication 701 and the association 702 are completed, the radio base station apparatus 11 establishes the communication link 25 with the communication terminal 35 and becomes communicable with the communication terminal 35.

  In step S <b> 502, the determination unit 113 determines whether a condition for switching the connection from the radio base station apparatus 11 to the radio base station apparatus 12 (radio base station switching condition) by the communication terminal 35 is satisfied. If the determination unit 113 determines that the radio base station switching condition is satisfied, step S503 is executed. On the other hand, when the determination unit 113 determines that the radio base station switching condition is not satisfied, step S502 is executed again. That is, the determination in step S502 is repeated until the radio base station switching condition is satisfied. The above determination corresponds to the determination 704 in FIG.

  In step S503, the information transmission unit 114 transmits the takeover information to the radio base station apparatus 12. This corresponds to the takeover information 705 in FIG.

  In step S <b> 504, the switching transmission unit 115 of the radio base station apparatus 11 transmits a CSA frame including the channel number of the communication path 22 of the radio base station apparatus 12 to the communication terminal 35. This corresponds to the CSA frame 706 in FIG.

  Processing of radio base station apparatus 12 according to the present embodiment will be described with reference to FIG. 5B.

  In step S521, the establishing unit 122 receives the takeover information transmitted by the information transmitting unit 114 of the radio base station apparatus 11. This corresponds to the takeover information 705 in FIG.

  In step S522, the establishing unit 122 establishes a connection with the communication terminal 35 using the control information included in the takeover information received in step S521. This corresponds to communication possible 712 in FIG.

  In step S523, the wireless communication unit 121 starts communication with the communication terminal 35 using the sequence number included in the takeover information. Specifically, the wireless communication unit 121 describes the sequence number included in the takeover information in the sequence number field of the data frame transmitted in the wireless communication with the communication terminal 35 via the communication link 26. In this way, by transmitting the sequence number from the radio base station apparatus 11 to the radio base station apparatus 12, the communication performed by the radio base station apparatus 11 (radio communication unit 111) and the communication terminal 35 is taken over. This can be performed by the radio base station apparatus 12 (the radio communication unit 121) and the communication terminal 35.

  Processing of the communication terminal 35 according to the present embodiment will be described with reference to FIG.

  In step S601, the communication terminal 35 performs authentication and connection establishment with the radio base station apparatus 11. The above authentication and connection establishment correspond to Authentication 701 and Association 702 in FIG. 7, respectively. When the authentication 701 and the association 702 are completed, the communication terminal 35 establishes the communication link 25 with the radio base station apparatus 11 and becomes communicable with the radio base station apparatus 11.

  In step S602, the communication terminal 35 enters a state of waiting for reception of a CSA frame (CSA frame 706 in FIG. 7) from the radio base station apparatus 11. Upon receiving the CSA frame 706, the communication terminal 35 executes step S603.

  In step S603, the communication terminal 35 acquires the switching destination channel number included in the CSA frame.

  In step S604, the communication terminal 35 performs channel switching 711 on the switching destination channel number acquired in step S603. As a result, the communication terminal 35 is in a state where the communication link 26 is established in the communication path 22 of the wireless communication terminal 12, and becomes communicable 712 with the wireless base station device 12.

  In step S604, the communication terminal 35 does not perform authentication and connection establishment with the radio base station apparatus 12, and does not receive a beacon for confirming the existence of a communication path. Communication with the device 12 is possible. This is because the channel switching 711 in step S604 is realized by the DFS function. The DFS function is originally used for the radio base station apparatus to switch the channel of its own communication path. Therefore, the radio base station apparatus starts using the switching destination channel after transmitting the CSA frame while having the control information generated by the authentication and connection establishment with the communication terminal before the channel switching. The communication terminal already has control information generated with the radio base station apparatus, and communication with the radio base station apparatus can be continued even after channel switching using the control information. In addition, since the communication terminal is determined by the DFS function that a communication channel by the radio base station apparatus is provided for the switching destination channel, the communication terminal can communicate without confirming the existence of the communication channel.

  Hereinafter, AP switching in a wireless communication system including a plurality of communication terminals using AP switching by a communication terminal performed as described above will be described.

  FIG. 8 is an explanatory diagram of a first usage example of AP switching by the communication terminal according to the present embodiment. A radio communication system 41 illustrated in FIG. 8 includes a radio base station apparatus 11, a radio base station apparatus 12, a LAN 31, and communication terminals 35a to 35c. FIG. 8 shows a case where all three communication terminals perform AP switching.

  In FIG. 8, the communication terminals 35a to 35c have initially established communication links 25a to 25c with the radio base station apparatus 11, respectively. In this state, the radio base station apparatus 11 transmits a CSA frame 801 (corresponding to the CSA frame 706 in FIG. 7) by broadcast transmission destined for all terminals.

  Each of the communication terminals 35a to 35c that has received the CSA frame 801 performs connection switching to the radio base station apparatus 12 by executing the connection switching process shown in FIG. As a result, the communication terminals 35a to 35c establish communication links 26a to 26c with the radio base station apparatus 12, respectively. Note that, when establishing the communication links 26a to 26c, communication is possible without performing authentication, connection establishment, or confirmation of a communication path.

  By doing in this way, all the communication terminals that have established a connection with the radio base station apparatus 11 can be switched to a state in which a connection with the radio base station apparatus 12 has been established.

  FIG. 9 is an explanatory diagram of a second usage example of AP switching by the communication terminal according to the present embodiment.

  The radio communication system 42 illustrated in FIG. 9 includes the radio base station apparatus 11, the radio base station apparatus 12, a LAN 31, and communication terminals 35a to 35c. FIG. 9 shows a case where only one of the three communication terminals performs AP switching.

  In FIG. 9, initially, the communication terminals 35 a to 35 c have established communication links 25 a to 25 c with the radio base station apparatus 11, respectively. In this state, the radio base station apparatus 11 transmits a CSA frame 901 (corresponding to the CSA frame 706 in FIG. 7) by unicast transmission destined for the communication terminal 35a.

  The communication terminal 35a that has received the CSA frame 901 performs connection switching to the radio base station apparatus 12 by executing the connection switching process shown in FIG. As a result, the communication terminal 35a establishes a communication link 26a with the radio base station apparatus 12. Note that when establishing the communication link 26a, the communication terminal 35a enters a communicable state without performing authentication, connection establishment, or confirmation of the communication path.

  In this way, it is possible to switch the designated one of the communication terminals that have established a connection with the radio base station apparatus 11 to a state in which a connection with the radio base station apparatus 12 has been established. By using this, the connection can be switched to the optimum radio base station apparatus according to the position of each communication terminal. Also, it is possible to perform load distribution between the radio base station devices by connecting the communication terminals to the surrounding radio base station devices.

  There are various methods for determining a radio base station apparatus to which an AP is switched by a communication terminal. For example, when the wireless base station device 11 and the like share the position information of its own device with other wireless base station devices and the communication terminal is moving, each neighboring wireless base station The optimum radio base station apparatus may be determined as the switching-destination radio base station apparatus based on the distance to the apparatus or the radio wave condition and the received signal strength of the radio wave received from each radio base station apparatus.

  As described above, according to the radio base station apparatus according to the present embodiment, the radio communication system can cause the communication terminal to perform AP switching using the DFS function. Specifically, the radio communication system is configured such that the communication paths between the first radio base station and the second radio base station are different frequency channels and have the same BSSID. . And a communication terminal can be in the state which established the connection with the 2nd wireless base station by changing only a frequency channel by the DFS function from the state which established the connection with the 1st wireless base station. Since the channel change by the DFS function is used in this way, authentication, connection establishment, or communication path existence confirmation is performed when the communication terminal establishes a connection with the second radio base station after switching the frequency channel. The AP switching can be completed without any problem. In addition, the wireless communication system does not require a device or function corresponding to a communication management device that centrally manages the communication status of the wireless base station or the communication terminal, and is based on the function of the wireless base station and the communication terminal. Realized. Therefore, the wireless communication system can complete AP switching by the communication terminal in a shorter time without using the communication management device.

  Also, the wireless communication system can make a determination based on the state of wireless communication by the communication terminal, and can perform AP switching by the communication terminal based on the determination result.

  In addition, in the wireless communication system, a communication terminal that has established a connection with the first wireless base station moves away from the first wireless base station, or there is a shield in the communication path between the first wireless base station and the communication terminal. As a result, when it is detected that the received signal strength received by the first radio base station from the communication terminal is less than the threshold, AP switching in the communication terminal can be performed. This is because, in this situation, it is considered that the wireless communication by the communication terminal is better when the AP is switched.

  In addition, the wireless communication system moves so that the communication terminal established with the first wireless base station moves closer to the second wireless base station, or shields that existed in the communication path between the second wireless base station and the communication terminal. When it is detected that the received signal strength received by the second radio base station from the communication terminal is equal to or higher than the threshold due to the loss of objects, AP switching by the communication terminal can be performed. This is because, in this situation, it is considered that the wireless communication by the communication terminal is better when the AP is switched.

  Further, the communication terminal can continue the encrypted communication performed with the first radio base station before the AP switching with the second radio base station after the AP switching.

  In addition, the wireless communication system can cause only the determined communication terminal to perform AP switching after determining the communication terminal to perform AP switching. Thereby, for example, only the communication terminal that has moved away from the first radio base station or only the communication terminal that has a shield in the communication path with the first radio base station can perform AP switching.

  In addition, the wireless communication system can cause all communication terminals established with the first wireless base station to perform AP switching. As a result, for example, when the first radio base station is stopped for some reason, the communication terminal established with the first radio base station can be switched to the second radio base station.

  In addition, the wireless communication system can perform AP switching using a CSA frame in the DFS function, which is a general-purpose technology. That is, if the communication terminal is compatible with the DFS function, the above AP switching can be performed without implementing any other special function.

  As described above, the wireless communication system of the present invention has been described based on the embodiment, but the present invention is not limited to this embodiment. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can think to this embodiment, and the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

  For example, in the embodiment, the description has been given on the assumption that the radio base station apparatus is a pair (two), but in an actual radio communication system, there may be a case where there are three or more radio base station apparatuses. Also in this case, if the frequency channels used for each radio base station are allocated in advance so as not to overlap, the embodiments described so far can be applied.

  The present invention can be used for a wireless communication system that completes AP switching by a communication terminal in a short time without using a communication management device. Specifically, it can be used for a wireless communication system or a wireless LAN access point in a wireless LAN or a public wireless LAN in a factory or office.

11, 12 Radio base station apparatus 21, 22 Communication path 21A, 22A Attribute information 25, 25a, 25b, 25c, 26, 26a, 26b, 26c Communication link 31 LAN
35, 35a, 35b, 35c Communication terminal 40, 41, 42 Wireless communication system 101 CPU
102 ROM
103 RAM
104 Storage device 105 WNIC
106 NIC
111, 121 Wireless communication unit 112, 122 Establishment unit 113 Determination unit 114 Information transmission unit 115 Switching transmission unit 401, 706, 801, 901 CSA frame 411 Switching destination channel number 421, 705 Takeover information 431 Control information 432 Sequence number

Claims (11)

A wireless communication system comprising a first wireless base station and a second wireless base station connected to the first wireless base station via a network,
The first radio base station is
A first wireless communication unit capable of performing wireless communication with a communication terminal on a first communication path specified by the first frequency channel and BSSID (Basic Service Set Indentifier);
A first establishment unit for establishing a first communication link with the communication terminal by generating control information necessary for wireless communication with the communication terminal via the first wireless communication unit by authentication and connection establishment;
An information transmitter for transmitting the handover information including the control information to the second radio base station;
A switching notification frame including changing the frequency channel of the wireless communication by the communication terminal to a second frequency channel different from the first frequency channel by a DFS (Dynamic Frequency Selection) function is sent via the first wireless communication unit. A switching transmission unit for transmitting to the communication terminal.
The second radio base station is
A second wireless communication unit capable of performing wireless communication with the communication terminal on a second communication path specified by the second frequency channel and the BSSID;
A wireless communication system comprising: a second establishment unit that establishes a second communication link with the communication terminal after receiving the switching notification frame using the takeover information received from the first wireless base station. The first radio base station further includes
After the first establishment unit generates the control information, the determination unit includes a determination unit that determines whether a condition determined from the state of wireless communication by the communication terminal is satisfied,
The information transmitting unit
When the determination unit determines that the condition is satisfied, the handover information is transmitted,
The switching transmission unit
The wireless communication system according to claim 1, wherein the switching notification frame is transmitted when the determination unit determines that the condition is satisfied. The determination unit
The wireless communication system according to claim 2, wherein when the first wireless communication unit detects that the received signal strength of the radio wave received from the communication terminal is less than a threshold value, the condition is satisfied. The second wireless communication unit further includes:
Detecting the received signal strength of radio waves received from the communication terminal,
The determination unit
The wireless communication system according to claim 2, wherein the condition is determined to be satisfied when it is detected that the received signal strength detected by the second wireless communication unit is equal to or greater than a threshold value. The control information is used for encrypted wireless communication between the first wireless base station and the communication terminal, and includes a dynamically generated shared key,
The wireless communication according to any one of claims 1 to 4, wherein the handover information further includes a sequence number to be described in a data frame used for wireless communication between the first wireless base station and the communication terminal. Communications system. The switching transmission unit
A destination determination unit that determines a destination of the switching notification frame by the switching transmission unit;
The switching transmission unit
The wireless communication system according to claim 1, wherein the switching notification frame is unicast-transmitted to the destination determined by the destination determination unit. The wireless communication system according to any one of claims 1 to 5, wherein the switching transmission unit broadcasts the switching notification frame. The switching notification frame is a CSA (Channel Switch Announcement) frame in the DFS function, and is a CSA frame including the channel number of the second frequency channel as a switching destination channel number. The wireless communication system described. A control method of a radio communication system comprising a first radio base station and a second radio base station connected to the first radio base station via a network,
The first radio base station is
A first wireless communication unit capable of performing wireless communication with a communication terminal on a first communication path specified by a first frequency channel and BSSID (Basic Service Set Indentifier);
The second radio base station is
A second wireless communication unit capable of performing wireless communication with the communication terminal on a second communication path specified by the second frequency channel and the BSSID;
The wireless communication system control method includes:
A first establishment step of establishing a first communication link with the communication terminal by generating control information necessary for wireless communication with the communication terminal via the first wireless communication unit by authentication and connection establishment;
An information transmission step of transmitting handover information including the control information to the second radio base station;
A switching notification frame including changing the frequency channel of the wireless communication by the communication terminal to a second frequency channel different from the first frequency channel by a DFS (Dynamic Frequency Selection) function is sent via the first wireless communication unit. A switching transmission step for transmitting to the communication terminal;
A control method for a radio communication system, comprising: a second establishment step of establishing a second communication link with the communication terminal after receiving the switching notification frame using the takeover information received from the first radio base station.   The program for making a computer perform the control method of the radio | wireless communications system of Claim 9.   A radio base station apparatus comprising a first radio base station or a second radio base station in the radio communication system according to claim 1.

Images