JP4634851B2 - Handover method, C-planeWireless Controller device, base station and terminal station - Google Patents

Description

  The present invention relates to a handover method that can be employed in a wireless LAN system, and more particularly, to a handover method when executing 802.1x authentication in a wireless LAN system.

  Conventionally, as a wireless LAN system (IEEE802.11) composed of a plurality of base stations (AP), for example, in a wireless LAN system used in an environment where a user moves, such as an office, the user's movement It is important for the terminal to perform handover and maintain communication quality while switching base stations.

  For example, as a handover in a wireless LAN system, “a wireless LAN system, a station, and a network switching method” described in Patent Document 1 below is disclosed. Here, the base station gives its own network information by Beacon. Thus, a method for performing network switching is disclosed.

JP 2004-229225 A

  However, the prior art described in Patent Document 1 focuses only on security without authentication as defined in 802.11, and there is no description regarding 802.1x authentication, which is security including authentication such as IEEE802.11i and WPA. If it is used as it is, reconnection is performed, so there is a problem that the instantaneous interruption time becomes long.

  In addition, the conventional technique described in Patent Document 1 has a problem that there is no description of handover across subnets.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a handover method when executing 802.1x authentication for security such as IEEE802.11i and WPA.

  Another object of the present invention is to obtain a handover method in the case of executing a handover across subnets after executing the 802.1x authentication.

  In order to solve the above-described problems and achieve the object, a handover method according to the present invention has a function of managing the state of a terminal station, and has a plurality of base stations constituting a predetermined area set at the same frequency In addition, in a wireless LAN system comprising a CWC (C-plane Wireless Controller) device that manages the plurality of base stations and terminals, and a terminal station, a specific base station is in a state of the terminal station by a predetermined authentication process. Is updated to “Association + authentication completed”, in which the specific base station transmits predetermined information (terminal station information) on the terminal station to the CWC device, and the CWC device Forwards the received terminal station information to a plurality of adjacent handover candidate base stations (HO candidate base stations), and each HO candidate base station that has received the terminal station information indicates the status of the terminal station. A first step of updating the state to “Pre-Association” representing the state before connection, and when the terminal station determines that a handover needs to be performed, a handover notification (HO notification) is handed over A second step of transmitting to the base station determined to be over (HO destination base station), and the HO destination base station updates the state of the terminal station to “Association + authentication completed”, and the received HO notification Is transferred to the CWC device, and further, a route learning frame is transmitted to the network device, and then the HO target base station triggers reception of downlink user data from the network device. Then, the handover completion notification (HO completion notification) is transmitted to the CWC device, and the CWC device that has received the HO completion notification sends the switching completion notification to the specific base station (HO Transmitted to the base station), HO source base station receiving the switching completion notification, and wherein a fourth step of updating the status of the terminal station to the "Pre-Association".

  According to the present invention, the handover method in the case of performing 802.1x authentication is defined, and the CWC centrally manages the subordinate APs and STAs belonging to the respective APs. As a result, it is possible to efficiently take over the security information between APs, and the time required for reconnection can be greatly reduced. That is, according to the present invention, it is possible to realize a handover with an extremely short interruption time.

  Hereinafter, an embodiment of a handover method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a wireless LAN system that implements a handover method according to the present invention. This wireless LAN system is a system compliant with IEEE802.11, and has, for example, a CWC (C-plane Wireless Controller) 1 that manages a plurality of base stations and has different BSSIDs (A, B,...) A plurality of base stations (AP) 2-1, 2-2,... Constituting a virtual AP area (Virtual-AP) set at the frequency f 0, and a terminal station (STA) 3 existing in the AP area; It has.

  Here, the configuration and operation of the CWC 1, each AP, and the STA 3 configuring the wireless LAN system will be described individually.

  FIG. 2 is a diagram showing an example of the configuration of the CWC 1. In particular, various messages sent from subordinate APs (2-1, 2-2,...) Are analyzed, and various messages to subordinate APs are analyzed. A message generation / analysis unit 11 that generates a message, a storage unit 12 that stores information about each AP and the STAs 3 belonging to those APs, and a STA state (STA state) as a pre-connection state (hereinafter, “Pre-Association”) And a state management instructing unit 13 for instructing to make a transition to (calling).

  In FIG. 2, the message generation / analysis unit 11 analyzes a message such as a handover notification (HO notification), STA information, or handover completion (HO completion) sent from the AP, and indicates the analysis result as a state management instruction. Notification to the unit 13. Then, a message is generated according to the instruction from the state management instruction unit 13. In addition, the storage unit 12 stores the STA status and STA information of each AP and STAs belonging to those APs. Status management instruction unit 13 transits the STA state based on information received from the AP. In addition to the state transitions (Idle, Authentication, Association) defined by IEEE802.11, the state management instruction unit 13 manages “Pre-Association”, which is a state before connection by handover. To do.

  FIG. 3 is a diagram illustrating a configuration example of the AP (2-1, 2-2). In particular, various messages sent from subordinate STAs and CWC1 are analyzed, and various messages for the STAs and CWC1 are analyzed. A message generation / analysis unit 21 that generates a message, a state management unit 22 that manages the state of the STA based on the STA information, and a route learning frame for updating the route information to the network device at the time of handover A route learning function unit 23 and a storage unit 24 that stores STA information and STA state are provided.

  In FIG. 3, a message generation / analysis unit 21 analyzes STA information (including Key information, MACAddress, etc.) and HO notification sent from the STA using a wireless LAN channel, and the result is a state management unit. 22 and the storage unit 24. In addition, STA information (including Key information, MACAddress, etc.), switching completion notification, and the like sent from CWC 1 using a wired network are analyzed, and the result is notified to state management unit 22 and storage unit 24. In addition, STA information received from the STA, HO notification, HO completion generated by an instruction from the state management unit 22 when handover is completed, and the like are transmitted to the CWC 1 using the wired network. In addition, the user data received from the STA and the network side is transferred to each destination. Note that the message generation / analysis unit 21 not only receives normal IEEE802.11 frames (STA information, user data, etc. from the STA) in the wireless LAN, but also receives unique frames (HO notifications, etc.). The unique frame may be distinguished using, for example, an IEEE 802.11 frame format and using an empty bit in the header portion.

  Further, the state management unit 22 updates the STA state of the STA 3 that is in the area and each STA that exists in the vicinity based on the STA information, the HO notification, the switching completion notification, and the like that are notified from the message generation / analysis unit 21. For example, when the STA 3 performs a handover, the route learning function unit 23 transmits a route learning frame (route information update) for updating the data route to the higher-level network device.

  FIG. 4 is a diagram illustrating a configuration example of the STA 3. In particular, a handover (HO) determination unit 31 that determines whether or not to execute a handover, various messages transmitted from the AP, In addition to a message generator / analyzer 32 that generates various messages for the AP, a state manager 34 that manages the status of the local station, a storage unit 33 that stores various information, and transmission / reception of normal IEEE802.11 frames And a wireless transmission / reception unit 35 having a function of transmitting a unique frame.

  In FIG. 4, the handover determination unit 31 monitors the reception state (reception power, etc.) of the frame, and determines whether or not to execute the handover based on the result. In addition to the STA state generation process and the user data generation / analysis process, the message generator / analyzer 32 has a function of generating a unique frame (HO notification) addressed to the handover destination AP when the handover execution is determined. Have. Further, the state management unit 34 and the storage unit 33 manage and store the state of the own station. Further, the wireless transmission / reception unit 35 checks the MAC address addressed to the own station and the current BSSID, and receives a plurality of user data from the handover destination AP or the handover source AP.

  Next, the operation of the wireless LAN system configured as described above will be described with reference to the drawings. FIG. 5 is a diagram showing the operation of each device constituting the wireless LAN system of the present embodiment, that is, the sequence of the handover method according to the present invention.

  In FIG. 5, for example, when the STA 3 turns on the power in the service providing area of the AP 2-1, an authentication process (802.1x authentication) is executed between the STA 3 and the AP 2-1 (step S1). At this time, the STA 3 transmits its own STA information (including Key information, MACAddress, etc.) to the AP 2-1 using the wireless LAN channel, and the AP 2-1 stores the received STA information, Furthermore, the STA state of the STA 3 is updated to “Association + authentication completed” based on the STA information (step S2). AP 2-1 transfers the STA information of STA 3 to CWC 1 using a wired network (step S3).

  Then, the CWC1 stores the received STA information, and further transfers the STA information of the STA3 using a wired network to a plurality of adjacent handover candidate APs (2-2, etc.) (step S4). . At this time, each handover candidate AP that has received the STA information stores the received STA information, and further updates the STA state of the STA 3 to “Pre-Association” based on the STA information (step S5). In this state, communication between the STA 3 and the AP 2-1 can be executed.

  After that, for example, when it is determined by STA3 that reception state monitoring (reception power comparison, etc.) should perform handover (step S6), STA3 generates a unique frame (HO notification), for example, The HO notification is transmitted to the AP 2-2 determined as the handover destination using the wireless LAN channel (step S7). The AP 2-2 that has received the HO notification updates the STA state of the STA 3 to “Association + authentication completed” (step S8), and transfers the received HO notification to the CWC 1 using a wired network (step S8). S9). Further, the AP 2-2 generates a route learning frame and transmits the route learning frame to the network device (step S10).

  Thereafter, the AP 2-2 is triggered by the reception of the downlink user data from the network device, recognizes the completion of the route information update, that is, the completion of the handover (Step S11), generates a HO completion notification, and generates the HO. A completion notification is transmitted to the CWC 1 using a wired network (step S12). The CWC 1 that has received the HO completion notification generates a switching completion notification and transmits the switching completion notification to the handover source AP 2-1 using the wired network (step S13). The AP 2-1 that has received STA updates the STA state of the STA 3 to “Pre-Association” (step S14).

  In FIG. 5, the downlink user data destined for STA 3 that relays AP 2-1 is different in BSSID from when STA 3 transmits a unique frame (HO notification) until the path learning of the network device ends. Therefore, it is discarded (step S15).

  As described above, in this embodiment, a handover method in the case of performing 802.1x authentication is defined, and the CWC centrally manages the subordinate APs and STAs belonging to the respective APs. As a result, it is possible to efficiently take over the security information between APs, and the time required for reconnection can be greatly reduced. That is, according to the present embodiment, it is possible to realize a handover with an extremely short interruption time.

  In the present embodiment, as shown in FIG. 5, STA 3 that relays AP 2-1 after STA 3 transmits a unique frame (HO notification) until the path learning of the network device ends. However, the present invention is not limited to this, and the configuration may be such that the downlink user data can be received. For example, when receiving the downlink user data, the wireless transceiver 35 checks the current BSSID, and receives user data from both the handover destination AP and the handover source AP based on the result. That is, even when the STA 3 transmits a unique frame (HO notification) and the path learning of the network device ends, in the case of the BSSID of the handover destination AP or the handover source AP, the user It is assumed that data can be received.

  In addition, for example, the wireless transmission / reception unit 35 checks whether the MAC address is addressed to the own station by a method different from the above, and based on the result, user data from both the handover destination AP and the handover source AP is obtained. It may be received. In other words, even if the STA 3 transmits a unique frame (HO notification) and the path learning of the network device ends, the user data can be received if the MAC address is addressed to the own station. . By the above two methods, data to be discarded can be greatly reduced.

Embodiment 2. FIG.
Next, the operation of the second embodiment will be described. In the first embodiment described above, the layer 2 handover that does not extend over the segment has been described. However, in the present embodiment, the layer 2 handover is realized by a method different from the first embodiment. The configuration of the wireless LAN system is the same as that of the first embodiment described above.

  Here, the configuration and operation of the CWC 1, each AP, and the STA 3 configuring the wireless LAN system will be described individually. In addition, about the structure similar to Embodiment 1 mentioned above, the same code | symbol is attached | subjected and the description is abbreviate | omitted. Hereinafter, processing different from that of the first embodiment will be described.

  FIG. 6 is a diagram illustrating a configuration example of the CWC 1 according to the second embodiment. In addition to the configuration of the first embodiment described above, the handover information collection unit 14 and the handover determination unit 15 are further provided. ing. In FIG. 6, a message generation / analysis unit 11 analyzes messages such as STA information, reception status notifications, and HO completion notifications sent from the AP, and the analysis results are sent to a state management instruction unit 13 and a handover information collection unit. 14 is notified. Then, predetermined messages (terminal state update instruction, BSSID rewriting instruction, switching completion notification, etc.) are generated in accordance with instructions from the state management instructing unit 13 and the handover information collecting unit 14. Further, the handover information collecting unit 14 collects various reception conditions (reception power, transmission rate, etc.) necessary for the handover from both the handover source AP and the handover destination AP as the handover information. Further, the handover determination unit 15 determines whether or not to execute the handover based on the handover information. The storage unit 12 also stores the above handover information and other information related to the handover in addition to various information related to the AP and the STA.

  FIG. 7 is a diagram illustrating a configuration example of an AP according to the second embodiment, and further includes a measurement unit 25 in addition to the configuration of the first embodiment described above. In FIG. 7, a message generation / analysis unit 21 analyzes STA information (including key information, MAC address, etc.) and upstream traffic sent from the STA using a wireless LAN channel, and the result is a state management unit. 22, the measurement unit 25 and the storage unit 24 are notified. It also analyzes the STA status update instruction, BSSID rewrite instruction, switching completion notification, etc. sent from the CWC 1 using the wired network, notifies the status management section 22 and storage section 24 of the results, and further BSSID. The rewriting instruction (unique frame) is transferred to the STA using the wireless LAN channel. Also, the STA information received from the STA, the reception status of the upstream traffic, and the HO completion notification generated when the handover is completed are transmitted to the CWC 1 using the wired network. Also, the user data and the route learning frame are transferred to each destination.

  Further, the measurement unit 25 monitors the reception status of the STA whose STA state is “Association”, and also monitors the uplink data of the STA of “Pre-Association”. Note that an ACK defined by IEEE802.11 is not returned to an STA that is “Pre-Association”.

  FIG. 8 is a diagram illustrating a configuration example of the STA of the second embodiment. In addition to the configuration of the first embodiment described above, the BSSID switching instruction unit 36 is further provided, while the HO determination unit 31 is deleted. Has been. In FIG. 8, the message generator / analyzer 32 analyzes the BSSID rewrite instruction from the AP in addition to the STA state generation process and the user data generation / analysis process. Also, a BSSID rewriting instruction and a route learning frame that are unique frames are generated. Further, the BSSID switching instruction unit 36 switches the BSSID when receiving a BSSID switching instruction from the handover source AP.

  Next, the operation of the wireless LAN system configured as described above will be described with reference to the drawings. FIG. 9 is a diagram showing the operation of each device constituting the wireless LAN system of the present embodiment, that is, the sequence of the handover method according to the present invention.

  First, similarly to the first embodiment described above, after executing the processing of steps S1 to S5, the AP 2-1 receives data sent from the STA 3 using the channel of the wireless LAN, and performs handover. Various necessary reception conditions (reception power, transmission rate, etc.) are measured (step S21), and ACK is returned (step S22). Then, the reception status as the measurement result is transmitted to CWC 1 (step S23).

  At the same time, each AP (2-2 in FIG. 9) that is a candidate for the handover destination monitors the uplink data of STA3 whose STA state is “Pre-Association” (does not return IEEE802.11 ACK). Then, various reception situations (reception power, transmission rate) necessary for the handover are measured (step S24). Then, the reception status as the measurement result is transmitted to CWC 1 (step S25).

  The CWC 1 receives the reception status of the STA 3 from the AP 2-1 and each AP that is a handover destination candidate, and determines whether or not to execute the handover based on the reception status (step S26). For example, when it is determined that the AP 2-2 needs to be switched, a STA state change notification is transmitted to the handover destination AP 2-2 using the wired network (step S27). Upon receiving the STA state change notification, the AP 2-2 changes the STA state of the STA 3 to “Association + authentication completed” (step S28).

  Thereafter, the CWC 1 transmits a BSSID switching instruction to the handover source AP 2-1 using the wired network (step S29), and the AP 2-1 uses the wireless LAN channel for the STA 3. The BSSID switching instruction (unique frame) is transferred (step S30), and the STA3 executes a process of switching the BSSID (step S31). In addition, after receiving the BSSID switching instruction, the handover source AP 2-1 changes the STA state of the STA 3 to “Pre-Association” (step S32).

  Thereafter, the AP 2-2 is triggered by the reception of the downlink user data from the network device, recognizes the completion of the route information update, that is, the completion of the handover (Step S11), generates a HO completion notification, and generates the HO. A completion notification is transmitted to the CWC 1 using a wired network (step S12). The CWC 1 that has received the HO completion notification generates a switching completion notification and transmits the switching completion notification to the handover source AP 2-1 using the wired network (step S13). The AP 2-1 that has received STA updates the STA state of the STA 3 to “Pre-Association” (step S14).

  In FIG. 9, the downlink user data addressed to STA 3 that relays AP 2-1 after STA 3 receives the unique frame (BSSID switching instruction) from AP 2-1 and ends the route learning of the network device. Are discarded because the BSSIDs are different (step S15).

  Thus, in this embodiment, the handover method in the case of performing 802.1x authentication is defined, and further, the CWC centrally manages the subordinate APs and STAs belonging to the respective APs, and the CWC It was decided whether or not to execute handover. As a result, it is possible to efficiently take over the security information between APs, and the time required for reconnection can be greatly reduced. That is, according to the present embodiment, it is possible to realize a handover with an extremely short interruption time.

  In the present embodiment, as shown in FIG. 9, during the period from when the STA 3 receives the unique frame (BSSID switching instruction) from the AP 2-1 until the path learning of the network device ends, the AP 2-2. Although the downlink user data addressed to STA3 that relays 1 is discarded, the present invention is not limited to this, and the downlink user data may be received. For example, when receiving the downlink user data, the wireless transceiver 35 checks the current BSSID, and receives user data from both the handover destination AP and the handover source AP based on the result. That is, even when the STA 3 receives the unique frame (BSSID switching instruction) from the AP 2-1 and finishes the route learning of the network device, it is the BSSID of the handover destination AP or the handover source AP. Is configured to be able to receive the user data.

  In addition, for example, the wireless transmission / reception unit 35 checks whether the MAC address is addressed to the own station by a method different from the above, and based on the result, user data from both the handover destination AP and the handover source AP is obtained. It may be received. That is, even if the STA3 receives a unique frame (BSSID switching instruction) from the AP 2-1 and the route learning of the network device ends, the user data is received if it is a MAC address addressed to itself. Make it possible. The two ways, it is possible to significantly reduce the data to be is discarded.

Embodiment 3 FIG.
Subsequently, the operation of the third embodiment will be described. In the present embodiment, in addition to the handover that does not cross the segments described in the first embodiment, a layer 3 handover that crosses the segments is realized. Note that the configuration of the wireless LAN system when performing a handover that does not cross segments is the same as that of the first embodiment.

  Here, the configuration and operation of CWC1, each AP, and STA3 (same configuration as FIG. 4 of the first embodiment) constituting the wireless LAN system will be described individually. In addition, about the structure similar to Embodiment 1 mentioned above, the same code | symbol is attached | subjected and the description is abbreviate | omitted. Hereinafter, processing different from that of the first embodiment will be described.

  FIG. 10 is a diagram illustrating a configuration example of the CWC 1 according to the third embodiment. In addition to the configuration of the first embodiment described above, an IP tunnel instruction unit 16 and an L3 handover determination unit 17 are further provided. . In FIG. 10, the message generation / analysis unit 11 further analyzes the L3 handover information sent from the AP in addition to the processing of the first embodiment, and notifies the L3 handover determination unit 17 of the analysis result. To do. Further, a message (IP tunnel setting instruction) for generating an IP tunnel is generated according to an instruction from the IP tunnel instruction unit 16. Further, the L3 handover determination unit 17 extracts information (for example, the AP address and STA address of the handover source) necessary for handover across subnets from the L3 handover information, and performs handover based on the information. It is determined whether the subnet of the STA to be executed is different, and if it is different, it is determined that the handover is across the subnets. The IP tunnel instruction unit 16 instructs the handover source AP and the handover destination AP to set the IP tunnel.

  FIG. 11 is a diagram illustrating a configuration example of an AP (2-1, 2-2, 2-3: 2-3 is an AP of another segment) according to the third embodiment, and the configuration according to the first embodiment described above. In addition, an IP tunnel setting unit 26 is further provided. In FIG. 11, in addition to the processing of the first embodiment, the message generation / analysis unit 21 further analyzes the IP tunnel setting instruction sent from the CWC 1 using the wired network and sets the result as the IP tunnel setting. Notify the unit 26. Further, the IP tunnel setting unit 26 sets an IP tunnel at a corresponding location when receiving an IP tunnel setting instruction.

  Next, the operation of the wireless LAN system configured as described above will be described with reference to the drawings. FIG. 12 is a diagram showing the operation of each device constituting the wireless LAN system of the present embodiment, that is, the sequence of the handover method according to the present invention.

  First, similarly to the first embodiment described above, after executing the processing of steps S1 to S5, when it is determined by STA3 that it is better to execute handover by reception status monitoring (reception power comparison, etc.) (step S41), STA3 generates a unique frame (HO notification) and transmits a HO notification using the channel of the wireless LAN to, for example, AP 2-3 of another segment determined to be a handover destination (step S41). S42).

  Then, in the handover destination AP 2-3 that has received the HO notification, information necessary for handover across subnets from the received HO notification (L3 handover information: for example, handover source AP address, STA address) The extracted L3 handover information is transmitted to the CWC 1 using a wired network (step S43).

  The CWC1 that has received the L3 handover information determines whether or not the original subnet of the STA3 that executes the handover is different based on the information, that is, whether or not the handover spans between subnets (step S44). If it is determined that the handover is across subnets, an IP tunnel generation instruction is transmitted to the handover source AP 2-1 and the handover destination AP 2-3 (step S45). Then, both APs generate an IP tunnel (step S46). Thereafter, data transfer is executed via the generated IP tunnel.

  As described above, in the present embodiment, when performing a layer 3 handover across segments, the handover source AP and the handover destination AP each generate an IP tunnel and perform data transfer via the IP tunnel. did. As a result, the IPv4 address is not changed in L3, so that the instantaneous interruption can be shortened. Moreover, since it is possible to use IPv4 instead of using MobileIP, it is possible to cope without changing the L3 protocol of the current device.

Embodiment 4 FIG.
Next, the operation of the fourth embodiment will be described. In the present embodiment, a layer 3 handover across segments is realized by a method different from that of the above-described third embodiment. At this time, in the present embodiment, a general STA that does not use a unique frame is used as the STA that executes the handover.

  Here, the configuration and operation of CWC1, each AP, and STA3 (general STAs conventionally used) constituting the wireless LAN system will be described individually. In addition, about the structure similar to Embodiment 1 mentioned above, the same code | symbol is attached | subjected and the description is abbreviate | omitted. In the following, processing different from that of the first to third embodiments will be described.

  FIG. 13 is a diagram illustrating a configuration example of the CWC 1 according to the fourth embodiment. In addition to the configuration of the first embodiment described above, an IP tunnel instruction unit 16 and an L3 handover determination unit 17 are further provided. The state management instruction 13 has an authentication resumption instruction function. In FIG. 10, the message generation / analysis unit 11 analyzes the acceptance inquiry sent from the AP, and notifies the L3 handover determination unit 17 of the analysis result. Further, a message for generating an IP tunnel (IP tunnel setting instruction) and an acceptance response are generated according to an instruction from the IP tunnel instruction unit 16. The L3 handover determination unit 17 obtains information (L3 handover information) necessary for handover such as subnet information, AP address, and STA address of each AP at the time of acceptance inquiry, and determines whether or not the handover is across subnets. Determine. The IP tunnel instruction unit 16 instructs the handover source AP and the handover destination AP to set the IP tunnel. The state management instructing unit 13 has a function of instructing the handover destination AP to resume the authentication process by an acceptance response after setting the IP tunnel.

  Further, each AP (2-1, 2-2, 2-3) is configured in the same manner as in FIG. 11 of the fourth embodiment described above, and the message generation / analysis unit 21 of the present embodiment performs “Authentication”. When the frame is received from the STA, the "Authentication" frame is not returned, but an acceptance inquiry is generated, the acceptance inquiry is sent to the CWC, and when the acceptance response is received from the CWC, no reply is returned. The “Authentication” frame is transmitted to the STA. Further, the IP tunnel setting unit 26 sets an IP tunnel at a corresponding location when receiving an IP tunnel setting instruction.

  Next, the operation of the wireless LAN system configured as described above will be described with reference to the drawings. FIG. 14 is a diagram showing the operation of each device constituting the wireless LAN system of the present embodiment, that is, the sequence of the handover method according to the present invention.

  First, when the STA 3 determines that it is better to execute the handover (step S51), the STA 3 generates an “Authentication” frame and, for example, wirelessly transmits to the AP 2-3 of the other segment determined as the handover destination. An “Authentication” frame is transmitted using the LAN channel (step S52).

  Then, the AP 2-3 of the handover destination that has received the “Authentication” frame generates an acceptance inquiry without immediately returning the “Authentication” frame, and uses the wired network to the CWC 1 for the acceptance inquiry. (Step S53).

  The CWC 1 that has received the acceptance inquiry obtains the L3 handover information at the acceptance inquiry, determines whether or not the handover is across subnets based on the information (step S54), and determines that the handover is across subnets. In this case, an IP tunnel generation instruction is transmitted to the handover source AP 2-1 and the handover destination AP 2-3 (step S55). Then, both APs generate an IP tunnel (step S56). Further, after transmitting the IP tunnel generation instruction, the CWC 1 transmits an acceptance response to the handover destination AP 2-3 using the wired network, and resumes the “Association + authentication” process (step S57).

  Thereafter, EAP / authentication, inquiry to the DHCP server, and communication of user data are performed via the IP tunnel generated between the handover destination AP 2-3 and the handover source AP 2-1.

  As described above, in this embodiment, when a general STA that does not use a unique frame performs a layer 3 handover across segments, the handover source AP and the handover destination AP each generate an IP tunnel. Therefore, data transfer is performed via the IP tunnel. As a result, the IPv4 address is not changed in L3, so that the instantaneous interruption can be shortened. Moreover, since it is possible to use IPv4 instead of using MobileIP, it is possible to cope without changing the L3 protocol of the current device.

  As described above, the handover method according to the present invention is useful for a wireless LAN system, and is particularly suitable as a handover method compatible with 802.1x authentication.

It is a figure which shows the structural example of the wireless LAN system which implement | achieves the hand-over method concerning this invention. 3 is a diagram illustrating a configuration example of a CWC according to Embodiment 1. FIG. 3 is a diagram illustrating a configuration example of an AP according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of a STA according to Embodiment 1. FIG. It is a figure which shows an example of the sequence of the hand-over method concerning this invention. 6 is a diagram illustrating a configuration example of a CWC according to Embodiment 2. FIG. 6 is a diagram illustrating a configuration example of an AP according to a second embodiment. FIG. 6 is a diagram illustrating a configuration example of a STA according to Embodiment 2. FIG. It is a figure which shows an example of the sequence of the hand-over method concerning this invention. FIG. 10 is a diagram illustrating a configuration example of a CWC according to a third embodiment. FIG. 10 is a diagram illustrating a configuration example of an AP according to the third embodiment. It is a figure which shows an example of the sequence of the hand-over method concerning this invention. FIG. 10 is a diagram illustrating a configuration example of a CWC according to a fourth embodiment. It is a figure which shows an example of the sequence of the hand-over method concerning this invention.

Explanation of symbols

1 CWC
2-1, 2-2 Base station (AP)
3 Terminal station (STA)
DESCRIPTION OF SYMBOLS 11 Message production | generation / analysis part 12 Memory | storage part 13 State management instruction | indication part 14 Handover information collection part 15 Handover determination part 16 IP tunnel instruction | indication part 17 L3 handover determination part 21 Message generation / analysis part 22 State management part 23 Path | route learning function Unit 24 storage unit 25 measurement unit 26 IP tunnel setting unit 31 handover (HO) determination unit 32 message generation unit / analysis unit 33 storage unit 34 state management unit 35 wireless transmission / reception unit 36 BSSID switching instruction unit

Claims (20)

A plurality of base stations having a function of managing the state of the terminal station and constituting a predetermined area set at the same frequency; a CWC (C-plane Wireless Controller) device for managing the plurality of base stations and terminals; In a wireless LAN system comprising a terminal station, a handover method after a specific base station updates the state of the terminal station to “Association + authentication completed” by a predetermined authentication process,
The specific base station transmits predetermined information (terminal station information) regarding the terminal station to the CWC device, and the CWC device receives the received terminal station information as a plurality of adjacent handover candidate base stations. A first step in which each HO candidate base station that has transferred to (HO candidate base station) and received the terminal station information updates the state of the terminal station to “Pre-Association” indicating the state before connection; ,
When the terminal station determines that the handover needs to be performed, the base station (HO destination) that determines the handover notification (HO notification) to notify the base station that the handover is to be performed is the handover destination. A second step of transmitting to the base station);
The HO-destination base station updates the state of the terminal station to “Association + authentication completed”, transfers the received HO notification to the CWC device, and further transmits a route learning frame to the network device. 3 steps,
Thereafter, the HO destination base station sends a handover completion notification (HO completion notification) for notifying that handover has been completed at the HO destination base station, triggered by reception of downlink user data from the network device. The CWC device that transmitted to the CWC device and received the HO completion notification transmits the switch completion notification to the specific base station (HO source base station), and the HO source base station that received the switch completion notification , A fourth step of updating the state of the terminal station to “Pre-Association”;
A handover method comprising:   The terminal station receives downlink user data from both the HO destination base station and the HO source base station from when the HO notification is transmitted until the path learning of the network device ends. The handover method according to claim 1. A plurality of base stations having a function of managing the state of the terminal station and constituting a predetermined area set at the same frequency; a CWC (C-plane Wireless Controller) device for managing the plurality of base stations and terminals; In a wireless LAN system comprising a terminal station, a handover method after a specific base station updates the state of the terminal station to “Association + authentication completed” by a predetermined authentication process,
The specific base station transmits predetermined information (terminal station information) regarding the terminal station to the CWC device, and the CWC device receives the received terminal station information as a plurality of adjacent handover candidate base stations. A first step in which each HO candidate base station that has transferred to (HO candidate base station) and received the terminal station information updates the state of the terminal station to “Pre-Association” indicating the state before connection; ,
A second step in which the specific base station and the HO candidate base station measure a reception situation necessary for handover using data transmitted from the terminal station, and transmit the reception situation to the CWC device; ,
When the CWC device determines that it is better to execute a handover based on the received reception status, it transmits a state change notification to the base station (HO destination base station) determined to be the handover destination, A third step in which the HO-destination base station updates the state of the terminal station to “Association + authentication completed”;
The CWC device transmits a BSSID switching instruction to the specific base station (HO source base station), the HO source base station updates the state of the terminal station to “Pre-Association”, and A fourth step of transferring a BSSID switching instruction to the terminal station;
A fifth step in which the terminal station performs a process of switching the BSSID, and further transmits a route learning frame to the network device via the HO destination base station;
Thereafter, the HO-destination base station transmits a handover completion notification (HO completion notification) to the CWC device triggered by reception of downlink user data from the network device, and receives the HO completion notification. The device transmits a switching completion notification to the specific base station (HO source base station), and the HO source base station that has received the switching completion notification updates the state of the terminal station to “Pre-Association”. A sixth step;
A handover method comprising:   The terminal station receives downlink user data from both the HO destination base station and the HO source base station after receiving the BSSID switching instruction from the HO source base station until the path learning of the network device is completed. The handover method according to claim 3, wherein the handover method is received. A plurality of base stations having a function of managing a state of the terminal station, constituting a predetermined area, a CWC (C-plane Wireless Controller) device for managing the plurality of base stations and terminals, and a terminal station; In a wireless LAN system provided, a handover method between different segments after a specific base station updates the state of the terminal station to “Association + authentication completed” by a predetermined authentication process,
The specific base station transmits predetermined information (terminal station information) regarding the terminal station to the CWC device, and the CWC device receives the received terminal station information as a plurality of adjacent handover candidate base stations. A first step in which each HO candidate base station that has transferred to (HO candidate base station) and received the terminal station information updates the state of the terminal station to “Pre-Association” indicating the state before connection; ,
A second step of transmitting a handover notification (HO notification) to a base station (HO destination base station) determined to be a handover destination when the terminal station determines that a handover needs to be executed; When,
A third step in which the HO destination base station extracts information necessary for handover between subnets (handover information) from the received HO notification and transmits the handover information to the CWC device;
When the CWC device determines that the handover is between subnets based on the received handover information, the CWC device issues an IP tunnel generation instruction to the specific base station (HO source base station) and the HO destination base station. A fourth step of transmitting;
A fifth step in which the HO source base station and the HO destination base station each generate an IP tunnel;
Including
Thereafter, a handover method characterized by executing data transfer via the generated IP tunnel. When performing handover between different segments,
A fifth step of transmitting an “Authentication” frame to a base station (HO-destination base station) determined to be a handover destination when the terminal station determines that a handover needs to be performed;
A sixth step in which the HO-destination base station generates an acceptance query without returning an “Authentication” frame, and transmits the acceptance query to the CWC device;
When the CWC device obtains information necessary for handover between subnets (handover information) at the time of acceptance inquiry, and determines that the handover is between subnets based on the handover information, A seventh step of transmitting an IP tunnel generation instruction to the base station (HO source base station) and the HO destination base station;
An eighth step in which the HO source base station and the HO destination base station each generate an IP tunnel;
Thereafter, the CWC device transmits an acceptance response to the HO-destination base station, and resumes the authentication process (“Authentication” frame reply), ninth step;
Including
2. The handover method according to claim 1 , wherein the EAP / authentication, inquiry to the DHCP server, and communication of user data are executed via the generated IP tunnel. A CWC (C-plane Wireless) that configures a wireless LAN system together with a plurality of base stations that have a function of managing the state of the terminal station and configure a predetermined area set at the same frequency, and manages each of the base stations and terminals Controller) device,
State management instruction means for transitioning the state of the terminal station held by the base station;
Storage means for storing predetermined information about the base station and the terminal station;
With
The state management instruction means includes
By transferring predetermined information (terminal station information) about the terminal station sent from the base station at the time of terminal authentication to a plurality of adjacent handover candidate base stations (HO candidate base stations), the HO candidate Transition the state of the terminal station held by the base station to "Pre-Association" that represents the state before connection,
Further, when the HO completion notification is received from the handover destination base station (HO destination base station), the switching completion notification is transmitted to the handover source base station (HO source base station), and the HO source base station The CWC device is characterized in that the state of the terminal station held by the device is shifted from “Association + authentication completed” to “Pre-Association”. Further, handover for determining whether or not to execute handover based on “reception status of data transmitted from terminal to HO source base station” sent from the HO source base station and HO candidate base station Determination means,
With
The state management instruction means includes
When the handover determination means determines that it is better to execute the handover, by transmitting a state change notification to the base station determined to be the handover destination (HO destination base station), the HO destination base station Transition the state of the terminal station held by “Pre-Association” to “Association + Authentication Complete”
In addition, when the handover determination unit determines that it is better to execute the handover, by transmitting a BSSID switching instruction to the HO source base station, the state of the terminal station held by the HO source base station is changed. 8. The CWC device according to claim 7, wherein a transition is made from “Association + authentication completed” to “Pre-Association”. Furthermore, based on information necessary for handover (handover information) sent from the HO-destination base station, L3 handover determination means for determining whether to execute handover between subnets;
IP tunnel instruction means for instructing the HO source base station and the HO destination base station to generate an IP tunnel when the L3 handover determination means determines that it is necessary to execute handover between subnets;
The CWC device according to claim 7, comprising: When the terminal station determines that it is necessary to execute handover between different segments , the terminal station transmits an “Authentication” frame to the base station (HO destination base station) that has been determined as the handover destination, and the HO destination In a situation where the base station transmits an acceptance inquiry to its own device without returning an “Authentication” frame, based on information necessary for handover (handover information) obtained by the acceptance inquiry, L3 handover determination means for determining whether to execute handover;
IP tunnel instruction means for instructing the HO source base station and the HO destination base station to generate an IP tunnel when the L3 handover determination means determines that it is necessary to execute handover between subnets;
After the IP tunnel is generated, an acceptance response is transmitted to the HO-destination base station, and authentication processing is resumed (“Authentication” frame reply);
The CWC device according to claim 7, further comprising: In a base station constituting a wireless LAN system together with a CWC (C-plane Wireless Controller) device that manages the base station and the terminal,
State management means for managing the state of the terminal station;
Storage means for storing predetermined information about the terminal station (terminal station information);
With
The state management means includes
Update the status of the corresponding terminal station to “Association + Authentication Completed” by the prescribed authentication process.
When the terminal station information sent from the CWC device is received, the state of the corresponding terminal station is updated to “Pre-Association” indicating the state before connection,
In addition, when the handover notification (HO notification) sent from the terminal station is received, the status of the corresponding terminal station is updated to “Association + authentication completed”
In addition, the base station is configured to update the state of the corresponding terminal station to “Pre-Association” when a switching completion notification sent from the CWC device is received. Furthermore, when receiving the HO notification, a route learning means for performing control for transmitting a route learning frame for updating the data route to the upper network device,
With
The state management means includes
Triggering reception of downlink user data from the network device as a trigger to recognize completion of data path update, and then performing control for transmitting a handover completion notification (HO completion notification) to the CWC device The base station according to claim 11. In a base station constituting a wireless LAN system together with a CWC (C-plane Wireless Controller) device that manages the base station and the terminal,
State management means for managing the state of the terminal station;
Storage means for storing predetermined information about the terminal station (terminal station information);
Measuring means for measuring the reception status required for handover using data transmitted by the terminal station, and transmitting the reception status to the CWC device;
With
The state management means includes
Update the status of the corresponding terminal station to “Association + Authentication Completed” by the prescribed authentication process.
When the terminal station information sent from the CWC device is received, the state of the corresponding terminal station is updated to “Pre-Association” indicating the state before connection,
In addition, when the status change notification sent from the CWC device is received, the status of the corresponding terminal station is updated to “Association + authentication completed”
Also, based on the reception status, the CWC device determines that it is necessary to perform handover, transmits a BSSID switching instruction, and when the instruction is received, the state of the corresponding terminal station is set to “Pre-Association” Updated to
In addition, the base station is configured to update the state of the corresponding terminal station to “Pre-Association” when a switching completion notification sent from the CWC device is received. Furthermore, the state management means includes
Triggering reception of downlink user data from the network device as a trigger to recognize completion of data path update, and then performing control for transmitting a handover completion notification (HO completion notification) to the CWC device The base station according to claim 13. Further, when performing a handover between subnets, an IP tunnel setting means for setting an IP tunnel connecting a handover destination subnet and a handover source subnet in accordance with an IP tunnel generation instruction sent from the CWC device ,
With
The base station according to claim 11 or 12, wherein after the IP tunnel is set, data transfer is performed via the IP tunnel. After the terminal station determines that it is necessary to execute a handover between different segments , if it receives an "Authentication" frame from the terminal station, it generates an acceptance query without returning an "Authentication" frame, Message generation and analysis means for transmitting an acceptance inquiry to the CWC device;
If it is determined in the acceptance inquiry that handover between subnets needs to be executed, an IP for connecting the handover destination subnet and the handover source subnet in accordance with an IP tunnel generation instruction sent from the CWC device IP tunnel setting means for setting a tunnel;
Further comprising
The message generation and analysis unit returns an “Authentication” frame that has not been returned to the terminal station when an acceptance response is received from the CWC device after setting the IP tunnel by the IP tunnel setting unit. The base station according to claim 11, wherein: A plurality of base stations according to claim 11 or 12 constituting a predetermined area set at the same frequency, and a CWC (C-plane that manages the base stations and terminal stations according to claims 11 or 12. (Wireless Controller) In a terminal station that forms a wireless LAN system together with a device,
When it is determined that the handover needs to be executed, the base station (HO destination base) that has determined that the handover notification (HO notification), which is a unique frame for notifying the base station to execute the handover, is the handover destination. Handover determination means for transmitting to the station),
A terminal station comprising:   Receiving downlink user data from both the HO destination base station and the handover source base station (HO source base station) from when the HO notification is transmitted until the path learning of the network device ends. The terminal station according to claim 17, characterized in that: 15. A plurality of base stations according to claim 13 or 14 constituting a predetermined area set at the same frequency, and a CWC (C-plane that manages the base stations and terminal stations according to claim 13 or 14 above. In the terminal station that together with the (Wireless Controller) device,
When it is determined that the CWC device needs to execute a handover and a BSSID switching instruction (unique frame) transferred from the handover source base station (HO source base station) is received, the BSSID switching instruction BSSID switching means for performing processing for switching BSSID from handover source to handover destination based on
A terminal station comprising:   Receiving downlink user data from both the handover destination base station and the HO source base station from when the BSSID switching instruction is received from the HO source base station until the path learning of the network device ends. The terminal station according to claim 19, characterized in that:

Images