JP7128922B2 - Wireless communication system, access point, and wireless communication method - Google Patents

Description

The present invention relates to a wireless communication system having a plurality of wireless LAN (Local Area Network) access points, an access point that performs wireless communication with a communication terminal, and a wireless communication method between the communication terminal and the access point.

In recent years, large-scale wireless communication systems have been installed in station premises, school buildings, company buildings, and the like. In such a wireless communication system, a large number of access points (APs) are arranged in order to increase the number of communication terminals connected to the entire network. Each access point periodically transmits a beacon containing information necessary for connection, and when the communication terminal receives the beacon, it transmits a connection request in response to the beacon and establishes a connection with the access point.

Patent Document 1 discloses a wireless communication system in which a communication terminal measures received signal strength from a beacon transmitted from each access point and determines an access point to be connected based on the measured received signal strength. .

JP 2016-63235 A

The frequency bandwidth used for beacon transmission is narrower than the frequency bandwidth used for data communication. Therefore, the beacon transmission speed is low and it takes time to transmit the beacon. In conventional wireless communication systems, all access points transmit beacons at regular intervals (often about 100 millisecond intervals). There is a problem that a sufficient speed cannot be secured.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a main object thereof is to provide a wireless communication system, an access point, and a wireless communication method capable of suppressing beacon transmission time.

In order to solve the above-described problems, a radio communication system according to one aspect of the present invention provides a first access point having a first radio communication unit that transmits a beacon, and a beacon transmitted from the communication terminal in response to the beacon. a second access point having a second wireless communication unit that transmits an association response corresponding to the association request.

In this aspect, the first wireless communication unit transmits the beacon including a MAC address indicating a transmission source, and the second wireless communication unit sends the association response including a MAC address that is the same as the MAC address as a transmission source. may be sent.

Further, in the above aspect, the wireless communication system includes a plurality of the second access points, the first wireless communication unit receives request data transmitted from the communication terminal in response to the beacon, and The wireless communication system includes a control unit provided in the first access point and determining a connection target from among the plurality of second access points for each MAC address of the communication terminal included in the request data; a first wired communication unit provided in one access point for transmitting, to the second access point determined as the connection target, notification data for notifying that the second access point is the connection target; and a second wired communication unit that receives the notification data transmitted from the first wired communication unit, wherein the second wireless communication unit receives the notification data by the second wired communication unit. , the association response addressed to the MAC address of the transmission source of the request data may be transmitted.

In the above aspect, when the second wired communication unit receives the notification data, the second wireless communication unit uses the MAC address included in the notification data as a destination and sends the beacon as the transmission source. Response data to the request data may be transmitted, including the MAC address as a source.

Further, in the above aspect, the wireless communication system includes a plurality of the second access points, the second wireless communication unit receives request data transmitted from the communication terminal in response to the beacon, and The radio communication system is provided in the second access point, and when the request data is received by the second radio communication unit, the declaration data declaring that the communication terminal is to be connected to the other communication terminal. Further comprising a second wired communication unit transmitting toward a second access point, the second wired communication unit transmitting the declaration data when the declaration data is not received from the other second access point and transmitting response data to the request data, which includes the MAC address of the transmission source of the request data as a destination and the MAC address of the transmission source of the beacon as a transmission source, and transmits the response data to the request data from the other second access point. When the declaration data is received, the declaration data may not be transmitted and the response data may not be transmitted.

In the above aspect, the second wireless communication unit receives request data transmitted from the communication terminal in response to the beacon, and the wireless communication system is provided in the first access point, 2 a control unit that determines a connection target of the communication terminal from among the plurality of second access points based on a reception state of the request data in a wireless communication unit; a first wired communication unit configured to transmit, to the second access point determined as a connection target by the method, notification data for notifying that the second access point is a connection target; provided in the second access point, the first wired communication unit a second wired communication unit that receives the notification data transmitted from the Response data to the request data may be transmitted, including the original MAC address as a destination and the MAC address of the transmission source of the beacon as a source.

Further, in the above aspect, the wireless communication system includes a plurality of the second access points, and the plurality of second wireless communication units provided in each of the plurality of second access points set different MAC addresses respectively. and the first wireless communication unit transmits a plurality of beacons separately including a plurality of MAC addresses set to the plurality of second wireless communication units as transmission sources, and the second wireless communication unit is receiving request data transmitted from the communication terminal in response to the beacon, and transmitting the MAC address when the request data includes the MAC address set in the second wireless communication unit as a destination. Response data may be sent to the request data, including the original.

In the above aspect, the first wireless communication unit may transmit the plurality of beacons in order by time division.

In the above aspect, the first radio communication unit may transmit the plurality of beacons in different directions by beamforming.

In the above aspect, the wireless communication system includes a plurality of access points each having a wireless communication unit set to either a first mode for transmitting beacons or a second mode for not transmitting beacons, The access point has the wireless communication unit set to the first mode and functions as the first access point, and the other access point has the wireless communication unit set to the second mode and functions as the second access point May function as a point.

Further, an access point according to another aspect of the present invention includes a communication unit that wirelessly communicates with a communication terminal, and an association response corresponding to an association request transmitted from the communication terminal in response to a beacon transmitted by another access point. and a control unit for causing the communication unit to transmit.

Further, in a wireless communication method according to another aspect of the present invention, a first access point transmits a beacon, a communication terminal receives the beacon, then transmits an association request in response to the beacon, and a second access point Send an association response corresponding to the association request.

According to the present invention, it is possible to reduce the beacon transmission time in the entire system.

1 is a schematic diagram showing the configuration of a radio communication system according to Embodiment 1; FIG. FIG. 2 is a block diagram showing the configuration of a first access point; FIG. FIG. 4 is a block diagram showing the configuration of a second access point; 4 is a flowchart (first half) showing the procedure of operation of the radio communication system according to Embodiment 1; 4 is a flowchart (second half) showing the operation procedure of the radio communication system according to Embodiment 1; 4 is a sequence diagram showing the flow of operations of the wireless communication system according to the first embodiment; FIG. FIG. 2 is a conceptual diagram showing the structure of a frame format specified in IEEE802.11; 4 is a conceptual diagram showing the configuration of a MAC header in a beacon frame according to Embodiment 1; FIG. 4 is a conceptual diagram showing the configuration of a MAC header in a probe request frame according to Embodiment 1; FIG. 4 is a conceptual diagram showing the configuration of a connection target list; FIG. 4 is a conceptual diagram showing the configuration of a MAC header in a probe response frame according to Embodiment 1; FIG. 4 is a conceptual diagram showing the configuration of a MAC header in a data frame (transmitted from a wireless node to a wired node) according to Embodiment 1; FIG. 4 is a conceptual diagram showing the structure of a MAC header in a data frame (transmitted from a wired node to a wireless node) according to Embodiment 1; FIG. FIG. 10 is a flowchart (first half) showing the operation procedure of the radio communication system according to the second embodiment; FIG. FIG. 11 is a flowchart (second half) showing the operation procedure of the radio communication system according to the second embodiment; FIG. FIG. 10 is a sequence diagram showing the flow of operations of the radio communication system according to the second embodiment; 10 is a flowchart (first half) showing the procedure of operation of the radio communication system according to Embodiment 3; 10 is a flowchart (second half) showing the procedure of operation of the radio communication system according to Embodiment 3; FIG. 12 is a sequence diagram showing the flow of operations of the radio communication system according to the third embodiment; FIG. 10 is a schematic diagram showing the configuration of a radio communication system according to Embodiment 4; FIG. 11 is a flowchart (first half) showing the procedure of operation of the radio communication system according to Embodiment 4; FIG. FIG. 11 is a flowchart (second half) showing the operation procedure of the radio communication system according to Embodiment 4; FIG. FIG. 12 is a sequence diagram showing the flow of operations of the radio communication system according to the fourth embodiment; FIG. 12 is a conceptual diagram showing the configuration of a MAC header in a beacon frame according to Embodiment 4; FIG. 11 is a conceptual diagram showing the configuration of a MAC header in a probe request frame according to Embodiment 4; FIG. 11 is a conceptual diagram showing the structure of a MAC header in an association response frame according to Embodiment 4; FIG. 12 is a schematic diagram showing the configuration of a radio communication system according to Embodiment 5; 11 is a flowchart (first half) showing the procedure of operation of the radio communication system according to Embodiment 5; 14 is a flowchart (second half) showing the procedure of operation of the radio communication system according to Embodiment 5; FIG. 11 is a sequence diagram showing the flow of operations of a radio communication system according to Embodiment 5;

Preferred embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
In the present embodiment, after a first access point transmits a beacon and receives a probe request transmitted by a communication terminal in response, connection with a communication terminal from among a plurality of second access points that do not transmit a beacon is performed. Determine your target. The second access point to be connected establishes connection with the communication terminal in response to the association request sent from the communication terminal.

FIG. 1 is a schematic diagram showing the configuration of a radio communication system according to this embodiment. As shown in FIG. 1, wireless communication system 100 includes one first access point 110 and multiple second access points 120 . Such a wireless communication system 100 is installed in buildings such as station premises, school buildings, company buildings, and the like. The first and second access points 110 and 120 are connected to a wired network 4 such as a wired LAN and can communicate with each other. Also, the first and second access points 110 and 120 are capable of wireless communication according to wireless standards IEEE802.11a/b/g/n/ac. A wireless LAN (WLAN) is configured by the first and second access points 110 and 120 .

Next, configurations of the first and second access points 110 and 120 will be described. FIG. 2 is a block diagram showing the configuration of the first access point 110. As shown in FIG. As shown in FIG. 2 , first access point 110 includes first wireless communication section 111 , first wired communication section 112 , and control section 113 .

The first wireless communication unit 111 is a communication module that enables wireless communication according to IEEE802.11a/b/g/n/ac, and has a plurality of antennas 111a for wireless communication. The communication terminal 6 (see FIG. 1) can perform wireless communication with the first wireless communication unit 111 according to IEEE802.11a, b, g, n, or ac.

The first wired communication unit 112 is an Ethernet communication module, and communicates via the wired network 4 with another device connected to the wired network 4 (the second access point 120 in the case of FIG. 1). It can be performed.

The control unit 113 includes a microprocessor, memory, etc., and controls communication by the first wireless communication unit 111 and the first wired communication unit 112 . Also, the control unit 113 determines the second access point 120 to be connected to the communication terminal 6 .

FIG. 3 is a block diagram showing the configuration of the second access point 120. As shown in FIG. As shown in FIG. 3 , the second access point 120 includes a second wireless communication section 121 , a second wired communication section 122 and a control section 123 . The second wireless communication unit 121 has a plurality of wireless communication antennas 121a. The configurations of the second wireless communication unit 121, the second wired communication unit 122, and the control unit 123 are the same as the configurations of the first wireless communication unit 111, the first wired communication unit 112, and the control unit 113. Therefore, its description is omitted.

The first wireless communication unit 111 of the first access point 110 and the second wireless communication units 121 of all the second access points 120 as described above are set to the same frequency band (channel) for wireless communication. . Therefore, the communication terminal 6 can perform wireless communication with the first and second access points 110 and 120 by using this channel. Also, the same MAC address (hereinafter referred to as “common MAC address”) and SSID (Service Set Identifier) are set for the first wireless communication unit 111 and all the second wireless communication units 121 .

On the other hand, the first wired communication unit 112 of the first access point 110 and the second wired communication units 122 of all the second access points 120 are set with mutually different MAC addresses (hereinafter referred to as “wired communication MAC addresses”). It is In wired communication between the first and second access points 110 and 120, all of the first and second access points 110 and 120 can be individually identified by this MAC address for wired communication.

Also, each of the control units 113 and 123 can be set to either a first mode in which beacons are transmitted by wireless communication or a second mode in which beacons are not transmitted. In this embodiment, controller 113 of first access point 110 is set to the first mode, and controller 123 of second access point 120 is set to the second mode. As a result, the first access point 110 periodically transmits beacons and the second access point 120 does not transmit beacons. By changing the setting of the control unit 113 of the first access point 110 from the first mode to the second mode and changing the setting of the control unit 123 of one second access point 120 from the second mode to the first mode, the beacon You can change the sender.

Next, operation of radio communication system 100 according to the present embodiment will be described. 4A and 4B are flowcharts showing the procedure of operation of radio communication system 100 according to the present embodiment, and FIG. 5 is a sequence showing the flow of operation of radio communication system 100 until connection is established with a communication terminal. It is a diagram.

First, the control unit 113 of the first access point 110 causes the first wireless communication unit 111 to periodically broadcast a beacon (step S101). FIG. 6 is a conceptual diagram showing the configuration of a frame format defined by IEEE802.11 (hereinafter referred to as "IEEE802.11 frame format"). The IEEE802.11 frame format consists of a physical header and a MAC frame, and the MAC frame includes a MAC header and data (payload) fields. The MAC header includes fields such as frame control, duration/ID, address 1, address 2, address 3, sequence control, address 4, and so on. Frames are classified into three types: management frames, control frames, and data frames, and the frame type is specified in the frame control field. In the case of communication only between wireless nodes (for example, between an access point and a communication terminal) (that is, when data is not transferred via an access point), the address 1 field stores the MAC address of the destination, and the address 2 field stores the destination MAC address. , the MAC address of the transmission source is stored, BSSID (Basic Service Set Identifier) is stored in the address 3 field, and NULL is set in the address 4 field. Here, BSSID is the MAC address for wireless communication of the access point. FIG. 7 is a conceptual diagram showing the structure of a MAC header in a beacon frame. A beacon frame is one of the management frames and has no specific destination because it is broadcast. Therefore, the address 1 field of the beacon frame is a broadcast (BC) address (FF:FF:FF:FF:FF:FF), and the address 2 and address 3 fields store common MAC addresses.

Please refer to FIG. Communication terminal 6 receives the above beacon on the channel used by first access point 110 and transmits a probe request in response to this beacon. FIG. 8 is a conceptual diagram showing the configuration of the MAC header in the probe request frame. The probe request frame is one of the management frames described above, and the address 1 field stores a common MAC address (that is, the MAC address stored in the address 2 field of the beacon frame) as the destination, and the address 2 field stores The MAC address of the communication terminal 6 itself is stored as the transmission source. Also, the above BSSID is stored in the address 3 field. The data field of the probe request frame stores the SSID set in the communication terminal 6 and the like. Further, when the communication terminal 6 supports beamforming, information indicating that it supports beamforming is added to the probe request frame.

Please refer to FIGS. 4A and 5 again. First wireless communication unit 111 of first access point 110 receives the probe request transmitted from communication terminal 6 (step S102), and control unit 113 refers to the SSID included in the probe request to determine whether to accept the request. It is determined whether or not (that is, whether or not it matches its own SSID) (step S103). If the request is not accepted (NO in step S103), control unit 113 terminates the process. On the other hand, if the request is accepted (YES in step S103), the control unit 113 determines the second access point 120 to be connected to the MAC address of the communication terminal 6 included in the address 2 field of the probe request frame ( step S104). In this process, the control unit 113 randomly determines connection targets from among all the second access points 120, or determines the second access points 120 to be connected in a predetermined order. method can determine the connection target. The probe request is received not only by the first access point 110 but also by the second access point 120, but the second access point 120 does not process the probe request.

Next, the control unit 113 stores the MAC address of the communication terminal 6 in association with the wired communication MAC address of the second access point 120 determined as the connection target (step S105). A connection target list area is provided in the memory of the control unit 113 . FIG. 9 is a conceptual diagram showing the configuration of the connection target list. In the connection target list, the MAC addresses of the communication terminals 6 as connection partners are stored in association with the MAC addresses for wired communication of all the second access points 120 that are connection targets at that time. Control unit 113 manages the connection status of second access point 120 based on this connection target list.

Each of the second access points 120 has an upper limit (for example, four) on the number of communication terminals 6 that can be connected at the same time. In the connection target determination process in step S104, the control unit 113 checks the connection target list and determines the connection target from among the access points 120 to which the number of connections of the communication terminal 6 has not reached the upper limit.

Please refer to FIGS. 4A and 5 again. Next, the control unit 113 causes the first wired communication unit 112 to transmit notification data indicating that the second access point 120 determined as the connection target is the connection target (step S106), and ends the process. This notification data includes the MAC address of the communication terminal 6 as the connection partner. As a result, the connection process is handed over from the first access point 110 to the second access point 120 determined to be the connection target. Since the common MAC address and SSID are the same between the first access point 110 and the second access point 120, the communication terminal 6 can access the second access point as if it were communicating wirelessly with the first access point 110. 120 can be in wireless communication.

The second wired communication unit 122 of the second access point 120 receives the notification data (step S107), and the control unit 123 of the second access point 120 stores the MAC address of the communication terminal 6 included in the notification data. (Step S108). The second access point 120 has received the probe request as described above. Control unit 123 refers to the probe request to determine whether communication terminal 6 can support beamforming (step S109). The propagation path to the communication terminal 6 is estimated from the reception state of (step S110). On the other hand, if beamforming is not supported (NO in step S109), control unit 123 shifts the process to step S111.

The control unit 123 causes the second wireless communication unit 121 to transmit a probe response to the stored MAC address of the communication terminal 6 (step S111). In the subsequent wireless communication processing, when the MAC address of the transmission source included in the wireless LAN frame received by the second access point 120 matches the stored MAC address, the control unit 123 receives the transmission frame from the communication partner. judge there is. Also, if the communication terminal 6 is compatible with beamforming, the phase of the signal transmitted from each antenna 121a of the second wireless communication unit 121 is controlled so that the radio wave intensity is maximized at the position of the communication terminal 6 .

FIG. 10 is a conceptual diagram showing the configuration of the MAC header in the probe response frame. The probe response frame is one of the management frames. The address 1 field stores the MAC address of the destination communication terminal 6, and the address 2 field stores the common MAC address of the second access point 120 as the source. Address is stored. A common MAC address is stored in the address 3 field as BSSID. The data field of the probe response frame stores parameters required for wireless connection such as SSID, channel, data rate, and the like.

Please refer to FIGS. 4A and 5 again. The communication terminal 6 receives the probe response, sets the wireless connection using the parameters included in the probe response, and then transmits an authentication request. The authentication request frame is a management frame for performing connection authentication using data according to a predetermined authentication method, such as a password. Since the contents of the MAC header in the authentication request frame are the same as the contents of the MAC header in the probe request frame, the description thereof will be omitted.

Second wireless communication unit 121 of second access point 120 to be connected receives the authentication request (step S112), and control unit 123 refers to data included in the authentication request and executes authentication processing. Note that the description of the case where the authentication process fails is omitted here. If the authentication succeeds, the control unit 123 causes the second wireless communication unit 121 to transmit an authentication response (step S113). The authentication response frame is a management frame indicating success of authentication processing. Since the contents of the MAC header in the authentication response frame are the same as the contents of the MAC header in the probe response frame, the description thereof will be omitted.

After completing the authentication phase in which the authentication request and the authentication response are sent and received as described above, the communication terminal 6 transmits an association request (“ASReq” in FIG. 5) addressed to the common MAC address. An association request frame is a management frame for requesting connection to an access point. The contents of the MAC header in the association request frame are the same as the contents of the MAC header in the probe request frame. That is, the address 1 field of the association request frame stores the common MAC address as the destination, and the address 2 field stores the MAC address of the communication terminal 6 itself as the source. The same common MAC address as the address 1 field is stored as BSSID in the address 3 field (see FIG. 8).

Please refer to FIGS. 4B and 5 again. Second wireless communication unit 121 of second access point 120 to be connected receives the association request (step S114), and control unit 123 determines whether or not to permit connection with communication terminal 6. FIG. The control unit 123 causes the second wireless communication unit 121 to transmit an association response (“ASRes” in FIG. 5) according to the determination result (step S115). Note that the description of the case of rejecting the connection with the communication terminal 6 is omitted here. The contents of the MAC header in the association response frame are the same as the contents of the MAC header in the probe response frame. That is, the address 1 field of the association response frame stores the MAC address of the destination communication terminal 6, and the address 2 field stores the common MAC address as the source. The same common MAC address as the address 2 field is stored as BSSID in the address 3 field (see FIG. 10).

The connection between the communication terminal 6 and the second access point is established by the communication terminal 6 receiving the association response. As a result, the communication terminal 6 can communicate with other communication devices connected to the wired network 4 or with other communication devices on the Internet (hereinafter referred to as "external communication devices") via the wired network 4. It becomes possible.

When performing data communication with an external communication device, communication terminal 6 transmits a data frame to connected second access point 120 . FIG. 11 is a conceptual diagram showing the structure of a MAC header in a data frame transmitted from a wireless node to a wired node. In a wireless LAN frame for communication from a wireless node to a wired node, the BSSID is stored in the address 1 field, the source MAC address is stored in the address 2 field, and the destination MAC address is stored in the address 3 field, The address 4 field is NULL. When communicating from the communication terminal 6 to an external communication device, as shown in FIG. 11, in the MAC header of the data frame, the common MAC address is stored as the BSSID in the address 1 field. The address 2 field stores the MAC address of the communication terminal 6 itself as the source, and the address 3 field stores the MAC address of the external communication device as the destination. The data field of the data frame stores the data body to be transmitted to the external communication device.

Please refer to FIGS. 4A and 5 again. The second access point 120 to be connected receives the data frame through the second wireless communication unit 121 (step S116), the control unit 123 converts the data frame into an Ethernet frame, and the second wired communication unit 122 transmits the data frame to the external communication device. (step S117).

Also, when data (Ethernet frame) is transmitted from the external communication device to the communication terminal 6, the Ethernet frame is received by the second wired communication unit 122 of the second access point 120 (step S118). The control unit 123 of the second access point 120 converts the Ethernet frame into a wireless LAN data frame, and the second wireless communication unit 121 transfers it to the communication terminal 6 (step S119). FIG. 12 is a conceptual diagram showing the structure of a MAC header in a data frame transmitted from a wired node to a wireless node. In a wireless LAN frame for communication from a wired node to a wireless node, the MAC address of the destination is stored in the address 1 field, the BSSID is stored in the address 2 field, the MAC address of the transmission source is stored in the address 3 field, The address 4 field is NULL. When communicating from an external communication device to the communication terminal 6, as shown in FIG. 12, in the MAC header of the data frame, the MAC address of the communication terminal 6 is stored in the address 1 field as the destination, and the BSSID is stored in the address 2 field. A common MAC address is stored. Also, the address 3 field stores the MAC address of the external communication device as the transmission source.

In wireless communication system 100 according to the present embodiment, second access point 120 that does not transmit a beacon establishes a wireless connection with communication terminal 6 instead of first access point 110 that transmits a beacon. FIG. 1 shows a state in which a plurality of communication terminals 6 are connected to a wireless communication system 100 according to this embodiment. Since the first and second access points 110, 120 share the same channel, SSID, MAC address of the first and second wireless communication units 111, 121, all the second access points 120 from the communication terminal 6, It is recognized as the first access point 110 that transmitted the beacon. Therefore, communication is actually performed between the communication terminal 6 and the second access point 120 by operating as if the communication terminal 6 were to perform wireless communication with the first access point 110 . In such a wireless communication system 100, a plurality of communication terminals 6 responding to beacons can be assigned to each of the second access points 120 for data transfer. can increase the number of connections.

In wireless communication system 100 according to the present embodiment, only first access point 110 transmits beacons, and second access point 120 is for data transfer. 2 is constant regardless of the number of access points 120, and the beacon transmission time in the entire system can be suppressed.

Also, by using beamforming, the S/N ratio of communication between the second access point 120 and the communication terminal is improved, thereby improving communication efficiency. In addition, beamforming enables high-precision wireless communication with a plurality of communication terminals 6 at the same time, further improving the throughput of the entire system.

(Embodiment 2)
In this embodiment, the first access point transmits a beacon, and in response, one of the second access points that receives the probe request transmitted from the communication terminal declares itself to be a connection target. do. The second access point to be connected establishes connection with the communication terminal in response to the association request sent from the communication terminal.

Since the configuration of the radio communication system according to the present embodiment is the same as the configuration of the radio communication system 100 according to Embodiment 1, the same components are denoted by the same reference numerals, and descriptions thereof are omitted. Note that, in the present embodiment, as in the first embodiment, all of the first and second wireless communication units 111 and 121 of the first and second access points 110 and 120 use the same channel, the same SSID, and the same MAC address (common MAC address).

The operation of the radio communication system according to this embodiment will be described. 13A and 13B are flowcharts showing the procedure of operation of the radio communication system according to this embodiment, and FIG. 14 is its sequence diagram. The control unit 113 of the first access point 110 causes the first wireless communication unit 111 to periodically broadcast a beacon (step S201). This beacon frame contains the broadcast address as the destination in the address 1 field, and the common MAC address as the source and BSSID in each of the address 2 and address 3 fields, as in the case of the first embodiment.

The communication terminal 6 receives the beacon and transmits a probe request accordingly. This probe request frame has a common MAC address in the address 1 field (destination), a MAC address of the communication terminal 6 itself in the address 2 field (source), and an address 3 field as in the case of the first embodiment. (BSSID) each contain a common MAC address.

A probe request sent from the communication terminal 6 is received by one or more second access points 120 (step S202). The control unit 123 of the second access point 120 refers to the SSID included in the probe request and determines whether or not to accept the request (that is, whether or not it matches its own SSID) (step S203). If the request is not accepted (NO in step S203), control unit 123 terminates the process. On the other hand, if the request is accepted (YES in step S203), control unit 123 determines whether or not second wired communication unit 122 has received declaration data from another second access point 120 (step S204). . The declaration data is data for declaring that the second access point 120 that is the transmission source is to be connected to the communication terminal 6 , and the second access point 120 that transmitted the declaration data will establish communication with the communication terminal 6 . acquire rights. That is, when second access point 120 receives declaration data transmitted from another second access point 120 (YES in step S204), second access point 120 does not have the right to communicate with communication terminal 6. , the control unit 123 terminates the process.

On the other hand, if second access point 120 has not received the declaration data (NO in step S204), control unit 123 transmits the declaration data to all other access points 120 on the second wire, for example, by broadcasting or multicasting. It is transmitted to the communication unit 122 (step S205). Thereby, the second access point 120 acquires the communication right with the communication terminal 6 . Note that when a plurality of second access points 120 transmit declaration data at the same time, the declaration data transmitted by each collide. In order to avoid such collisions, known collision avoidance methods such as CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) and RTS/CTS (Request to Send/Clear to Send) can be employed.

Control unit 123 of second access point 120 that has acquired the right to communicate stores the MAC address of communication terminal 6 as a communication partner (step S206). After that, the control unit 123 performs channel estimation for beamforming, transmission of probe responses, transmission and reception of authentication requests and authentication responses, and transmission and reception of association requests and responses, and establishes connection with the communication terminal 6 . Note that the processing after step S207 is the same as the processing after step S109 described in the first embodiment, so description thereof will be omitted.

In this embodiment, the second access point 120 that has transmitted the declaration data earliest acquires the right to communicate with the communication terminal 6 . Also, the second access point 120 whose number of simultaneous connections with the communication terminal 6 has reached the upper limit may determine not to accept the probe request in step S203. As a result, this second access point 120 will not try to connect to the communication terminal 6 beyond the above upper limit.

With the above configuration, by increasing the number of second access points 120 for data transfer, the number of connected communication terminals 6 can be increased. In addition, since only the first access point 110 transmits beacons, the beacon transmission time in the entire system can be reduced.

(Embodiment 3)
In this embodiment, a first access point transmits a beacon, and a plurality of second access points receive probe requests transmitted from communication terminals in response to this. Among the plurality of second access points, the one with the best probe request reception state is determined as a connection target. The second access point to be connected establishes connection with the communication terminal in response to the association request sent from the communication terminal.

Since the configuration of the radio communication system according to the present embodiment is the same as the configuration of the radio communication system 100 according to Embodiment 1, the same components are denoted by the same reference numerals, and descriptions thereof are omitted. Note that, in the present embodiment, as in the first embodiment, all of the first and second wireless communication units 111 and 121 of the first and second access points 110 and 120 use the same channel, the same SSID, and the same MAC address (common MAC address).

The operation of the radio communication system according to this embodiment will be described. 15A and 15B are flowcharts showing the procedure of operation of the radio communication system according to this embodiment, and FIG. 16 is a sequence diagram thereof. Control unit 113 of first access point 110 causes first wireless communication unit 111 to periodically broadcast a beacon (step S301). This beacon frame contains the broadcast address as the destination in the address 1 field, and the common MAC address as the source and BSSID in each of the address 2 and address 3 fields, as in the case of the first embodiment.

The communication terminal 6 receives the beacon and transmits a probe request accordingly. This probe request frame has a common MAC address in the address 1 field (destination), a MAC address of the communication terminal 6 itself in the address 2 field (source), and an address 3 field as in the case of the first embodiment. (BSSID) each contain a common MAC address.

A probe request sent from the communication terminal 6 is received by one or more second access points 120 (step S302). The control unit 123 of the second access point 120 refers to the SSID included in the probe request and determines whether or not to accept the request (that is, whether or not it matches its own SSID) (step S303). If the request is not accepted (NO in step S303), control unit 123 terminates the process. On the other hand, if the request is accepted (YES in step S303), control unit 123 causes second wired communication unit 122 to transmit reception state data to first access point 110 (step S304). This reception state data indicates the reception strength of the probe request at the second access point 120 and is information including the MAC address of the communication terminal 6 .

First wired communication unit 112 of first access point 110 receives the reception state data transmitted from second access point 120 (step S305). The control unit 113 of the first access point 110 refers to the reception state data received from each of the second access points 120, and determines the second access point 120 with the highest reception strength as a connection target (step S306).

Next, the control unit 113 associates and stores the wired communication MAC address of the second access point 120 determined as the connection target with the MAC address of the communication terminal 6 in the connection target list (step S307). The first wired communication unit 112 is caused to transmit notification data indicating that the second access point 120 determined as a target is a connection target (step S308), and the process ends. The connection target list and notification data are the same as the connection target list and notification data described in Embodiment 1, so description thereof will be omitted.

The control unit 123 of the second access point 120 determines whether or not the second wired communication unit 122 has received the notification data (step S309). If notification data has not been received (NO in step S309), control unit 123 terminates the process. On the other hand, when notification data is received (YES in step S309), control unit 123 stores the MAC address of communication terminal 6 included in the notification data (step S310). After that, the control unit 123 performs channel estimation for beamforming, transmission of probe responses, transmission and reception of authentication requests and authentication responses, and transmission and reception of association requests and responses, and establishes connection with the communication terminal 6 . Note that the processing after step S311 is the same as the processing after step S109 described in the first embodiment, so description thereof will be omitted.

In the present embodiment, the second access point 120 with the best probe request reception state is determined as the connection target with the communication terminal 6 . Thereby, the second access point 120 with which the communication state with the communication terminal 6 is good can be set as the connection target.

In the present embodiment, the reception strength of the probe request is used as an index of the communication state, and the second access point 120 with the best communication state is determined as the connection target, but the present invention is not limited to this. The data retransmission rate associated with data errors or packet collisions may be used as an indicator of the communication state, and the second access point 120 with the lowest retransmission rate may be determined as the connection target.

With the above configuration, by increasing the number of second access points 120 for data transfer, the number of connected communication terminals 6 can be increased. In addition, since only the first access point 110 transmits beacons, the beacon transmission time in the entire system can be reduced.

(Embodiment 4)
In the present embodiment, individual MAC addresses are set for each of the plurality of second access points. The first access point repeatedly transmits a beacon while switching the source MAC address. The source MAC address is an individual MAC address set for each second access point. A communication terminal that receives a beacon transmits a probe request to the MAC address set as the transmission source in this beacon, and the second access point set with the MAC address receives the probe request. The second access point that has received the probe request responds to the association request sent from the communication terminal and establishes connection with the communication terminal.

FIG. 17 is a schematic diagram showing the configuration of a radio communication system according to this embodiment. A radio communication system 400 according to the present embodiment includes one first access point 110 and a plurality of second access points 120a to 120d. Different MAC addresses (hereinafter referred to as “individual MAC addresses”) are set in the second wireless communication units 121 of the second access points 120a to 120d. Also, all of the first and second wireless communication units 111 and 121 of the first and second access points 110 and 120a to 120d are set to the same channel and the same SSID. The configurations of the first and second access points 110, 120a to 120d are the same as those of the first and second access points 110, 120 described in Embodiment 1, so the same components are denoted by the same reference numerals. and the description thereof is omitted.

The first access point 110 sequentially transmits a plurality of beacons while switching the source MAC address. Each beacon separately includes the individual MAC address of each of the second access points 120a-120d as a source. For example, after a beacon containing the individual MAC address of the second access point 120a as a transmission source is transmitted, a beacon containing the individual MAC address of the second access point 120b as a transmission source is transmitted.

Next, operation of radio communication system 400 according to the present embodiment will be described. 18A and 18B are flowcharts showing the procedure of operation of radio communication system 400 according to the present embodiment, and FIG. 19 is a sequence diagram showing the flow of operation of radio communication system 400 until connection is established with a communication terminal. It is a diagram. In the following description, the second access points 120a-120d are also referred to as the second access point 120. FIG.

Control unit 113 of first access point 110 causes first wireless communication unit 111 to transmit a beacon including an individual MAC address as a transmission source (step S401). The beacon will be explained more specifically. FIG. 20 is a conceptual diagram showing the structure of a MAC header in a beacon frame. As shown in FIG. 20, the address 1 field of the beacon frame is a broadcast address (FF:FF:FF:FF:FF:FF), and the address 2 and address 3 fields store individual MAC addresses.

Refer again to FIG. 18A. Next, the control unit 113 switches the transmission source MAC address to the next individual MAC address of the second access point 120 (step S402), and returns the process to step S401. Thereafter, by repeating the processing of steps S401 and S402, the first access point 110 sequentially transmits beacons while switching the source MAC address.

The communication terminal 6 receives the beacon and transmits a probe request accordingly. FIG. 21 is a conceptual diagram showing the configuration of the MAC header in the probe request frame. The individual MAC address of the source of the beacon is stored as the destination and BSSID in the address 1 field and the address 3 field of the probe request frame, respectively. The address 2 field stores the MAC address of the communication terminal 6 itself as the transmission source. For example, when the communication terminal 6a receives a beacon including the individual MAC address of the second access point 120a as the source, the communication terminal 6a transmits a probe request including the individual MAC address of the second access point 120a as the destination. On the other hand, when the communication terminal 6b receives a beacon containing the individual MAC address of the second access point 120b as the transmission source, the communication terminal 6b transmits a probe request containing the individual MAC address of the second access point 120b as the destination ( 17 and 19).

Refer again to FIG. 18A. The probe request transmitted from the communication terminal 6 is received by the second wireless communication unit 121 of the second access point 120 to which the destination individual MAC address is set (step S403). For example, a probe request containing the individual MAC address of the second access point 120a as a destination is received by the second access point 120a. On the other hand, a probe request containing the individual MAC address of the second access point 120b as the destination is received by the second access point 120b (see FIGS. 17 and 19).

Refer again to Figures 18A and 18B. The control unit 123 of the second access point 120 refers to the SSID included in the probe request and determines whether or not to accept the request (that is, whether or not it matches its own SSID) (step S404). If the request is not accepted (NO in step S404), control unit 123 terminates the process. On the other hand, if the request is accepted (YES in step S404), control unit 123 stores the MAC address of communication terminal 6 as a communication partner (step S405). After that, the control unit 123 performs channel estimation for beamforming, transmission of probe responses, transmission and reception of authentication requests and authentication responses, and transmission and reception of association requests and responses, and establishes connection with the communication terminal 6 . Note that the processing after step S406 is the same as the processing after step S109 described in the first embodiment, so description thereof will be omitted. However, in the frame transmitted from the communication terminal 6 to the second access point 120, the destination or BSSID, which is the common MAC address in the first embodiment, is the individual MAC address. In addition, in the frame transmitted from the second access point 120 to the communication terminal 6, the transmission source or BSSID, which is the common MAC address in the first embodiment, is the individual MAC address. For example, in the association response frame, the address 1 field stores the MAC address of the destination communication terminal 6, and the address 2 and address 3 fields store the individual MAC address as the source and BSSID (see FIG. 22).

In the present embodiment, the first access point 110 transmits beacons originating from the individual MAC addresses of the second access points 120a to 120d by time division. Therefore, multiple beacons containing individual MAC addresses can be efficiently transmitted without collision. Also, by increasing the number of second access points 120 for data transfer, the number of connected communication terminals 6 can be increased. In such a wireless communication system 400, only the first access point 110 transmits a beacon, so the beacon transmission time in the entire system can be reduced.

(Embodiment 5)
In the present embodiment, individual MAC addresses are set for each of the plurality of second access points. A first access point simultaneously transmits a beacon in each of a plurality of different directions. A second access point is arranged in the direction in which the beacon is transmitted, and the beacon contains the MAC address of the second access point arranged in the transmission direction as the transmission source. A communication terminal that receives a beacon transmits a probe request to the MAC address set as the transmission source in this beacon, and the second access point set with the MAC address receives the probe request. The second access point that has received the probe request responds to the association request sent from the communication terminal and establishes connection with the communication terminal.

FIG. 23 is a schematic diagram showing the configuration of radio communication system 500 according to the present embodiment. The first access point 110 has a directional antenna 111a (see FIG. 2) and can radiate radio waves in any direction. A plurality of beacon transmission areas 501a to 501f are provided around the first access point 110, and the first access point 110 individually transmits a beacon to each of the beacon transmission areas 501a to 501f. Second access points 120a to 120f are arranged in the beacon transmission areas 501a to 501f, respectively. The configurations of the first and second access points 110, 120a to 120f are the same as those of the first and second access points 110, 120a to 120d described in the fourth embodiment, so the same components are The same reference numerals are given and the description thereof is omitted.

The first access point 110 simultaneously transmits a plurality of beacons toward each of the beacon transmission areas 501a-501f. Each beacon contains, as a source, the individual MAC address of the second access point 120a-120f arranged in the transmission direction. For example, the beacon transmitted toward the beacon transmission area 501a contains the individual MAC address of the second access point 120a as the transmission source, and the beacon transmitted toward the beacon transmission area 501b contains the second MAC address as the transmission source. The individual MAC addresses of the two access points 120b are included.

The operation of the radio communication system according to this embodiment will be described. 24A and 24B are flowcharts showing the procedure of operation of the radio communication system according to this embodiment, and FIG. 25 is its sequence diagram. As described above, the control unit 113 of the first access point 110 causes the first wireless communication unit 111 to simultaneously transmit beacons including individual MAC addresses as transmission sources to the beacon transmission areas 501a to 501f (step S501). Since the configuration of the beacon frame in this embodiment is the same as the configuration of the beacon frame described in Embodiment 4, the description thereof will be omitted.

Communication terminal 6 receives a beacon transmitted toward the area in which it is located among beacon transmission areas 501a to 501f, and transmits a probe request accordingly. For example, the communication terminal 6a located in the beacon transmission area 501a receives the beacon including the individual MAC address of the second access point 120a as the transmission source, and transmits a probe request including the individual MAC address as the destination. On the other hand, the communication terminal 6b located in the beacon transmission area 501b receives the beacon including the individual MAC address of the second access point 120b as the transmission source, and transmits a probe request including the individual MAC address as the destination (FIG. 23 and See Figure 25). Since the structure of the probe request frame in this embodiment is the same as the structure of the probe request frame described in the fourth embodiment, the description thereof will be omitted.

Refer again to FIG. 24A. The probe request transmitted from the communication terminal 6 is received by the second access point 120 to which the destination individual MAC address is set (step S502). For example, a probe request containing the individual MAC address of the second access point 120a as a destination is received by the second access point 120a. On the other hand, a probe request containing the individual MAC address of the second access point 120b as the destination is received by the second access point 120b (see FIGS. 23 and 25).

Refer again to Figures 24A and 24B. The control unit 123 of the second access point 120 refers to the SSID included in the probe request and determines whether or not to accept the request (that is, whether or not it matches its own SSID) (step S503). If the request is not accepted (NO in step S503), control unit 123 terminates the process. On the other hand, if the request is accepted (YES in step S503), control unit 123 stores the MAC address of communication terminal 6 as a communication partner (step S504). After that, the control unit 123 performs channel estimation for beamforming, transmission of probe responses, transmission and reception of authentication requests and authentication responses, and transmission and reception of association requests and responses, and establishes connection with the communication terminal 6 . Note that the processing after step S505 is the same as the processing after step S109 described in the first embodiment, so description thereof will be omitted. However, in the frame transmitted from the communication terminal 6 to the second access point 120, the destination or BSSID, which is the common MAC address in the first embodiment, is the individual MAC address. In addition, in the frame transmitted from the second access point 120 to the communication terminal 6, the transmission source or BSSID, which is the common MAC address in the first embodiment, is the individual MAC address.

In this embodiment, the first access point 110 transmits a beacon whose transmission source is the individual MAC addresses of the second access points 120a to 120f by space division. Therefore, multiple beacons containing individual MAC addresses can be efficiently transmitted without collision. Also, by increasing the number of second access points 120 for data transfer, the number of connected communication terminals 6 can be increased. In such a wireless communication system 500, only the first access point 110 transmits a beacon, so the beacon transmission time in the entire system can be reduced.

(Other embodiments)
In Embodiments 1 to 5 described above, the first access point 110 is used for beacon transmission, but the present invention is not limited to this. The first access point 110 can also be configured to perform both beacon transmission and data communication. In this case, any one of the first access point 110 and all the second access points 120 becomes a connection target with the communication terminal 6 .

Further, in Embodiments 1 to 5, an access point that can be set to either the first mode or the second mode functions as the first access point 110 when set to the first mode, and functions as the second mode. Although the configuration functioning as the second access point 120 has been described, the configuration is not limited to this. The first access point 110 can be configured to have only the beacon transmission function, and the second access point 120 can be configured to have only the data communication function.

Further, in Embodiment 1, the first access point 110 receives a probe request transmitted from the communication terminal 6 in response to a beacon, determines the second access point 120 to which the communication terminal 6 is to be connected, and connects. Although the configuration in which the target second access point 120 executes the communication processing after the probe response has been described, the configuration is not limited to this. The first access point 110 can also perform communication processing (probe response transmission, authentication request reception, authentication response transmission, and association request reception) prior to transmission of an association response for establishing a connection. . For example, after the first access point 110 transmits a probe response and receives an authentication request, the second access point 120 to be connected transmits an authentication response, receives an association request, and transmits an association response. can also

Further, in Embodiment 1, the control unit 113 of the first access point 110 uses the received probe request to identify the second to-be-connected MAC address of the communication terminal 6 included as the source of the probe request. Although the configuration for determining the access point 120 has been described, it is not limited to this. The second access point 120 to be connected is determined using request data (authentication request, association request) other than the probe request, and the second access point 120 sends response data (authentication response, association response) corresponding to the request data. It may be configured to transmit to the communication terminal 6 . For example, the first access point 110 receives the authentication request as described above, and the second access point 120 to be connected can be determined for each MAC address of the communication terminal 6 included as the transmission source. In this case, the probe response is sent from the first access point 110 and the response data, the authentication response, is sent from the second access point 120 .

That is, the wireless communication system may have any of the following configurations.
(1) The first access point 110 transmits a beacon. The second access point 120 determined as a connection target transmits a probe response in response to the probe request transmitted from the communication terminal 6, transmits an authentication response in response to the authentication request transmitted from the communication terminal 6, and performs communication. An association response is sent in response to the association request sent from the terminal 6 .
(2) The first access point 110 transmits a beacon and transmits a probe response in response to the probe request transmitted from the communication terminal 6; The second access point 120 determined as a connection target transmits an authentication response in response to the authentication request transmitted from the communication terminal 6, and transmits an association response in response to the association request transmitted from the communication terminal 6.
(3) The first access point 110 transmits a beacon, transmits a probe response in response to the probe request transmitted from the communication terminal 6, and transmits an authentication response in response to the authentication request transmitted from the communication terminal 6. The second access point 120 determined as a connection target transmits an association response in response to the association request transmitted from the communication terminal 6 .

Also, in the second embodiment, the configuration has been described in which declaration data is transmitted when the second access point 120 receives a probe request from the communication terminal 6, but the configuration is not limited to this. When request data (authentication request, association request) other than a probe request is received, declaration data is transmitted, and response data (authentication response, association response) corresponding to the request data is sent from the second access point 120 to the communication terminal 6. It is good also as a structure which transmits. For example, when the second access point 120 receives an authentication request from the communication terminal 6, it can also send the declaration data. In this case, the probe response is sent from the first access point 110 and the response data, the authentication response, is sent from the second access point 120 .

Further, in Embodiment 3, the configuration for determining the second access point 120 to be connected based on the reception state of the probe request at the second access point 120 has been described, but the present invention is not limited to this. . Based on the reception state of request data (authentication request, association request) other than the probe request from the communication terminal 6, the second access point 120 to be connected is determined, and response data (authentication response, association request) corresponding to the request data is sent. response) to the communication terminal 6 from the second access point 120 . For example, the second access point 120 to be connected can be determined based on the reception status of the authentication request at the second access point 120 . In this case, the probe response is sent from the first access point 110 and the response data, the authentication response, is sent from the second access point 120 .

Further, in Embodiment 1, a configuration has been described in which connection targets are managed by storing the wired communication MAC address of the second access point 120 in the connection target list, but the present invention is not limited to this. . Information used for management is not limited to wired communication MAC addresses as long as each second access point 120 can be individually identified. Alternatively, the IP address assigned to the second wired communication unit 122 of each second access point 120 may be used.

A wireless communication system, an access point, and a wireless communication method according to the present invention are a wireless communication system having a plurality of wireless LAN access points, an access point that performs wireless communication with a communication terminal, and a wireless communication method between the communication terminal and the access point. Useful.

100 wireless communication system 110 first access point 111 first wireless communication unit 111a antenna 112 first wired communication unit 113 control unit 120 second access point 121 second wireless communication unit 121a antenna 122 second wired communication unit 123 control unit 6 communication terminal

Claims (4)

a first access point that transmits a plurality of beacons in different directions by beamforming;
a plurality of second access points that transmit association responses corresponding to association requests transmitted from communication terminals in response to the beacons;
each of the plurality of second access points is configured with a different MAC address;
The first access point transmits the plurality of beacons each including, as a transmission source, the MAC address of the second access point assigned in each direction in which the plurality of beacons are transmitted;
Each of the plurality of second access points, when the association request transmitted from the communication terminal in response to the beacon includes the MAC address set to the second access point as a destination, the MAC sending the association response to the association request, including an address as a source;
wireless communication system. A plurality of access points each having a wireless communication unit set to either a first mode for transmitting beacons or a second mode for not transmitting beacons,
The one access point has the wireless communication unit set to the first mode and functions as the first access point,
The other access point has the wireless communication unit set to the second mode and functions as the second access point.
A wireless communication system according to claim 1 . a communication unit that wirelessly communicates with a communication terminal;
a control unit that causes the communication unit to transmit an association response corresponding to an association request transmitted from the communication terminal in response to one of a plurality of beacons transmitted in different directions by beamforming from another access point,
the plurality of beacons transmitted by the other access points each include, as a transmission source, the MAC address of the access point assigned to each direction in which the plurality of beacons are transmitted;
When the association request transmitted from the communication terminal in response to the beacon includes the MAC address set to itself as a destination, the communication unit responds to the association request including the MAC address as a source. sending said association response;
access point. A first access point transmits a plurality of beacons in different directions by beamforming,
after the communication terminal receives the beacon, transmits an association request according to the beacon;
A wireless communication method in which one of a plurality of second access points transmits an association response corresponding to the association request,
each of the plurality of second access points is configured with a different MAC address;
The first access point transmits the plurality of beacons each including, as a transmission source, the MAC address of the second access point assigned in each direction in which the plurality of beacons are transmitted;
Each of the plurality of second access points, when the association request transmitted from the communication terminal in response to the beacon includes the MAC address set to the second access point as a destination, the MAC sending the association response to the association request, including an address as a source;
wireless communication method.

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