JP6218166B2 - Inter-base station handover method - Google Patents

Description

  The present invention relates to integrated control and network control technology for a wired network section and a wireless access section.

  Research and development aimed at realizing a new generation network around 2020 is active both in Japan and overseas. Among them, SDN (Software-Defined Network) and network that dynamically control and change the network configuration There is a great deal of technology research related to virtualization. The present invention relates to a network interface control technique and a network control technique related to integrated control of a wired network section and a wireless access section against the background of the above technical field.

  The communication network referred to in the present invention is a network used for packet communication. In general, packet communication is well known as asynchronous time division multiplexed communication. Further, the virtual network referred to in the present invention allows a communication path in packet communication to be virtually used as a dedicated communication path, can be used as a larger number of communication paths, or a band of communication paths. It is a network that can be used as a wider one. As such a virtual network technology, for example, a label switching technology for setting a communication route based on a label attached to a packet header separately from a normal header, or a flow switching for setting a communication route based on contents of a plurality of header areas Technology is known. The SDN includes a virtual network that can dynamically control and change the network configuration.

  In communication between a radio base station and a mobile terminal, various multiple access methods using techniques such as space division multiplexing, time division multiplexing, and frequency division multiplexing are used.

  In recent years, open flow technology has been introduced and put into practical use as a technology for dynamically controlling the configuration of wired network sections. On the other hand, a technique for dynamically controlling the configuration of the radio access section is also discussed in technical fields such as SDR.

  Hotspot 2.0 (Non-Patent Document 1) has been proposed as a technique for linking a plurality of wireless access networks and allowing a terminal to switch between the networks. Hotspot 2.0 links the authentication mechanisms of each wireless network and forwards an authentication request as a procedure for connecting a terminal to a certain base station to an authentication server having authentication information of the terminal. Achieve seamless connectivity.

  IEEE 802.11i (Non-Patent Document 2) is a standard that defines WLAN security standards and defines stronger encryption, authentication, and key management methods for data and system security. This standard includes two new data confidential protocols (TKIP (Temporal Key Integrity Protocol), AES (Counter Mode with Cipher Block Chaining Message Authentication Code Protocol)-CCMP (Counter Mode with Cipher Block Chaining Message Authentication Code Protocol)) and pre-authentication. Etc. are included. If the pre-authentication mechanism is used, the mobile terminal can switch base stations at high speed by completing the authentication procedure before switching the base station among the association procedures and authentication procedures required for connection to the base station. Become.

Hotspot 2.0: Wi-Fi CERTIFIED Passpoint: A new program from the Wi-Fi Alliance to enable seamless Wi-Fi access in hotspots, https://www.wi-fi.org/register.php?file=wp_20120619_Wi-Fi_CERTIFIED_Passpoint. pdf IEEE 802.11i: 802.11i-2004-IEEE Standard for information technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment 6: Medium Access Control (MAC) Security Enhancements, http://standards.ieee.org/getieee802/802.11.html

  However, in the method described in Non-Patent Document 1 or Non-Patent Document 2, when the terminal switches the base station, the association (connection) procedure is re-executed, and the connection in the data link layer between the base station and the terminal is temporarily disconnected. Will be. The present invention provides means for shortening the time required for handover between base stations.

The inter-base station handover method of the present invention includes:
In a wireless LAN system including a plurality of base stations, a mobile terminal, and a relay node in a communication network or a base station having a function corresponding to the relay node, from the first base station to which the mobile terminal is connected, In the inter-base station handover for switching the connection to the second base station,
(1) The relay node acquires terminal state information related to authentication and connection of the mobile terminal from information in the first base station to which any one of the mobile terminals is connected, and uses the acquired information as the second base station of the handover destination Notify the station in advance and share it,
(2) Using the notified terminal state information, the second base station executes a forced authentication / connection process in the wireless MAC layer for the mobile terminal, and executes an authentication / connection protocol with the terminal. Not by running internally,
(3) relay node will receive a completion notice of the authentication and connection process (2) from the second base station, to start multipath transmission, further, the relative disconnect instruction has been transmitted to the first base station in Rukoto to receive the disconnection completion notification from the first base station, switching to the second base station to forward the data from the first base station to the mobile terminal as the destination, thereby communicating the mobile terminal and the second base Only communication with the station,
(4) The first base station performs a forced disconnection process in the wireless MAC layer for the mobile terminal being connected without executing a disconnection protocol with the terminal. And

  The wireless LAN system is a system that employs WPA2 and CCMP as an authentication method and an encryption method, respectively, and the terminal state information in (1) includes at least a CCMP pair temporary key.

  The terminal state information (1) includes a CCMP pair temporary key and a CCMP packet number.

  The terminal state information (1) includes a CCMP pair temporary key, a CCMP packet number, and a WPA sequence counter.

  The terminal state information of (1) includes a CCMP pair temporary key, a CCMP packet number, a WPA sequence counter, and capability information.

  Also, the terminal state sharing method between base stations in the first base station is notified and shared to the second base station by broadcast communication or by unicast communication with the second base station as the destination. It is a method.

further,
( 5 ) The second base station of (2) immediately before the relay node or the base station having a function corresponding to the relay node requests the terminal state information from the first base station of (1). In the period from when the authentication / connection processing completion notification is received to the relay node, the base station having a function corresponding to the relay node temporarily interrupts and stores the transmission of the packet addressed to the mobile terminal. It is characterized by that.

Furthermore, when the frequency channel used by the second base station is different from the frequency channel used by the first base station,
( 6 ) Notification of forced switching to the frequency channel used by the second base station to the mobile terminal connected to the first base station, and the first base station to the terminal This is performed by unicasting a probe response frame in which the frequency channel is indicated in an announcement (CSA) field.

further,
( 7 ) After the authentication / connection process in the second base station of (2) is completed, the relay node or the base station having a function corresponding to the relay node copies a packet addressed to the mobile terminal, Each is simultaneously transmitted to the first base station and the second base station by multipath transmission.

The relay node or the base station having a function corresponding to the relay node is a first base station.

Further, the present invention is an inter-base station handover method for performing a handover between virtualized base stations,
The wireless LAN system is a network including a virtualization compatible base station, a virtualization compatible base station accommodating switch or a virtualization compatible base station having a function corresponding thereto, and a mobile terminal,
The virtualization-capable base station accommodating switch has a function of dynamically changing the amount of resource used in units of virtual networks,
The virtualized base station is connected to the virtualized base station accommodation switch as a relay node having a function corresponding to accommodate the switch or virtualized base station dynamically changes the use resource amount in virtualized network units It has a function to
In handover between base stations for switching the connection from the first virtualization compatible base station to which the mobile terminal is connected to the second virtualization compatible base station,
(1 v ) In the first virtualization compatible base station to which any one of the mobile terminals is connected, terminal state information related to the authentication and connection of the mobile terminal is acquired, and the acquired information becomes the second virtualization serving as a handover destination. Inform and share the corresponding base station in advance,
(2 v ) Using the notified terminal state information, the second virtualization compatible base station performs authentication / connection processing in the wireless MAC layer for the mobile terminal,
(3 v ) The first virtualization compatible base station performs handover between the virtualization compatible base stations, characterized in that the mobile terminal being connected performs disconnection processing at the wireless MAC layer. .

In addition,
(4) If the relay node has an OpenFlow switch function, authentication / connection processing is completed from the second base station in (2) immediately before requesting the terminal state information from the first base station in (1). In the period until receiving the notification, the packet transmission is temporarily stopped by delaying the packet-in procedure of the OpenFlow and the response to the packet-in in the OpenFlow controller for all the packets addressed to the mobile terminal. It is characterized by being interrupted and stored.

  When each mobile terminal connects to the wireless network continuously or intermittently, the time required for connection with the base station can be shortened by omitting the association process and the authentication process each time.

It is a figure which shows the whole wired / wireless integrated network of Example 1. FIG. It is a figure which shows the procedure of the new construction of a virtual network, and the procedure of a handover between virtual networks. It is a figure for demonstrating the function structure of the virtualization corresponding base station (vBS) and the virtualization corresponding base station accommodation switch (vBS-SW). It is a figure which shows the specific example of the handover between virtual networks by Open Flow. It is a figure which shows the specific example of the handover between virtual networks by Open Flow. It is a figure which shows the outline | summary of the handover between base stations. It is a figure which shows the procedure of the handover between base stations. It is a figure which shows the outline | summary of the hand-over between base stations in the case of the base station which can comprise vRF-I / F (bRF-I / F). It is a figure which shows the function structure of the WiFi base station (vBS) which can comprise vRF-I / F which enables execution of a handover between base stations (between vRF-I / F). It is a figure which shows the example of mounting of a WiFi base station (vBS). It is a figure which shows the example of mounting of a WiFi base station (vBS). It is a figure which shows the example of mounting of the virtualization corresponding base station accommodation switch (vBS-SW).

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, devices having the same function or similar functions are denoted by the same reference numerals unless there is a special reason.

  The present invention provides a wireless LAN system including a plurality of base stations and mobile terminals, and a relay node in a communication network or a base station having a function corresponding thereto, from a first base station to which the mobile terminal is connected to a second base station. This is an inter-base station handover method for switching a connection to a base station at high speed.

  The base station is connected to a relay node in the communication network via a wired link or a wireless link, and exchanges control information and data packets.

The base station may have a plurality of radio interfaces for accommodating terminals. The inter-base station handover method can also be applied to a handover in which a terminal switches a connection from a first radio interface of the base station to a second radio interface for a single base station having a plurality of radio interfaces. is there.

  In the base station, the wireless interface and the wired interface are connected via a bridge module. The bridge module performs data transfer at the data link layer between the wireless interface and the wired interface. The bridge module may perform data transfer at the network layer and operate as a router.

The relay node may exist in the communication network and may not be directly connected to the base station. Further, only control information may be exchanged with the base station.
There may be a mode in which there is no relay node and the base station has the function of a relay node instead.

  The relay node has a base station control function. The first base station control function uses the wireless interface usage status (average throughput, etc.) from the base station that it manages, and the association and authentication for each terminal generated by the association / authentication process between the terminal and the base station. This function acquires authentication information and the like. Information held for each terminal to which the base station is connected is referred to herein as a terminal state.

  The second base station control function of the relay node is a function for determining the handover timing of the terminal and the handover destination base station in consideration of the radio interface usage status, geographical location, etc., and notifying the base station It is.

  Based on the terminal state notified from the relay node, the base station has a function of internally executing association / authentication processing with the handover target terminal without executing the association / authentication protocol with the terminal.

  The present invention is a handover method in which a relay node leads a base station handover of a terminal by a base station control function possessed by the relay node and an internal execution function of authentication / connection processing possessed by the base station.

An overview of handover between base stations (H / O) is shown in FIG. It is predicted that the relay node acquires terminal state information relating to the association / authentication of the terminal in the first base station (1) to which the terminal (3) is connected, and that the acquired information becomes a handover destination. Notify the base station (2) in advance,
The second base station (2) uses the notified terminal state information to forcibly associate and authenticate the mobile terminal at the wireless MAC layer;
This is a handover method in which the first base station (1) simultaneously performs forcible disconnection processing at the wireless MAC layer on the connected mobile terminal.

  A method for realizing handover between base stations in the case of a wireless LAN (WiFi) base station that employs WPA2 and CCMP as an authentication method and an encryption method will be described below.

In a wireless LAN system employing CCMP (AES) as an encryption method, the terminal state specifically needs to include at least the following information.
-CCMP Pairwise Transient Key (384bit)
Also,
-CCMP packet number (48bit),
-WPA sequence counter (64bit),
-Capability information (16bit)
It is desirable to include
First, each role will be briefly described.

The CCMP pair temporary key is one of the key keys in the CCMP, and its constituent elements are (a) Key Confirmation Key (encryption key for sharing the Pairwise Master Key (PMK) between the base station and the terminal. KCK), (b) Key Encryption Key (KEK) for encrypting Group Transient Key (GTK), and (c) Temporal Key (TK) for encrypting individual data frames.
The CCMP pair temporary key of the handover target terminal is distributed by a procedure called a 4-way handshake between the terminal and the base station. The 4-way handshake exchanges parameters used to generate a Temporal Key (TK) and confirms that both sides are ready to start encrypted communication.
If the CCMP pair temporary key can be shared between the terminal and the base station, it is possible to decrypt the received frames encrypted on both sides.

The CCMP packet number (PN) is an ID that is sequentially assigned to each data frame. In the data frame, it is stored in the CCMP frame header. It can also be obtained by decoding the MIC (Message Integrity Code) field (8 bytes) in the data frame, which is used for data frame integrity checks. The packet number is used to check whether the data frame is a replay attack. Specifically, the packet number must be greater than or equal to the last received packet number among those that passed the integrity check.

The WPA sequence counter is information embedded in the frame header in the group key handshake for the purpose of sharing the Group Transient Key (GTK), which is executed following the 4-way handshake, and is usually a 64-bit NTP time stamp. Is used. Similarly to the above, it is used to check whether the handshake frame is a replay attack.

  Finally, the capability information is a bit string indicating the function supported by the terminal, and is targeted for the short preamble function, the short slot time function, and the like.

  When handing over from the first base station (1) to which the terminal (3) is connected to the second base station (2), the CCMP pair temporary key of the handover target terminal is first transferred to the second base station (2) that is the handover destination. By notifying in advance, the second base station (2) can encrypt the data part of the data frame transmitted to the terminal. Similarly, a data frame from the terminal can be decoded. That is, communication in the data link layer is physically possible with the handover destination base station.

In CCMP, not only the CCMP pair temporary key but also the CCMP packet number is used for encryption of the data frame. Even if the CCMP packet number is not notified to the second base station (2), the second base station (2) If the CCMP packet number of the transmitted data is larger than that of the frame sent from the first base station (1), the terminal does not discard the received frame and can continue processing in the data link layer.
If the transmission from the first base station (1) to the terminal is stopped and the transmission from the second base station (2) is continued, the CCMP packet number of the transmission frame from the second base station (2) will eventually be greater. Therefore, the terminal can perform normal processing without discarding the frame received from the second base station (2).
When the relay node (4) notifies the second base station (2) of the CCMP packet number, the terminal (3) receives from the first base station (1) up to a certain frame and starts from the next frame. The effect that the inter-base station handover without frame loss, such as reception from two base stations (2), can be obtained.

Even when the relay node (4) does not notify the second base station (2) of the WPA sequence counter, a new Group Transient Key (GTK) is exchanged between the second base station (2) and the CCMP packet number. It takes time to share.
However, even if the new GTK cannot be shared, the broadcast frame and the multicast frame cannot be encrypted / decrypted, and ordinary data frames can be transmitted / received and encrypted / decrypted.
When the relay node (4) notifies the second base station (2) of the WPA sequence counter, an effect is obtained that transmission / reception of a broadcast frame to / from the second base station becomes possible immediately at the time of handover.

Even when the relay node (4) does not notify the second base station (2) of the capability information, all the terminals that perform the handover have a common capability and can be shared in advance by the entire system, The terminal (3) can communicate with the second base station (2) in an appropriate communication mode by having the general capability and the second base station predicting it.
When the relay node (4) notifies the second base station (2) of the capability information, it is possible to select an appropriate communication mode even when the capability of the terminal is not known in advance. .

The terminal state can further include the following information as an option.
-Association ID (16bit),
-ht_capability (208bit),
-Station flag (32bit),
-Listen interval (16bit).
The association ID and listening interval are required when enabling sleep mode at the terminal, ht_capability is required at IEEE 802. When operating at 11n mode, and the station flag is required when enabling WMM at the terminal. Become.

The terminal state notification from the first base station (1) to the second base station (2) may be either a direct notification or an indirect notification relayed by the relay node. Direct notification is possible by broadcast communication or unicast communication destined for the second base station.
Neighboring base stations can be detected by a method in which each base station knows neighboring base stations in advance by broadcasting control information, and the base stations that can communicate with each other using the GPS information and geographic information of each base station. Possible ways to discover.
At this time, for the notification of the terminal state, a shared key is generated using a secure communication protocol such as SSH in the case of unicast, or a secure key exchange protocol in the group for multicast communication in the case of broadcast. The terminal state encrypted with the shared key is notified above.

FIG. 7 shows a procedure for inter-base station handover when the terminal (STA) (3) in FIG. 6 performs handover from the base station (1) to the base station (2).
Handover includes (a) handover preparation processing, (b) terminal state notification / sharing, (c) start transmission / reception at the H / O destination base station, (d) stop transmission / reception at the H / O source base station, ) It consists of five phases of handover completion processing.

(A) As handover preparation processing, buffering (temporary storage) of data addressed to the terminal is started, and if necessary, duplicate data detection and discard using the terminal as a transmission source is started. The buffering function of the wired node may be provided by the H / O destination base station. Further, the RF-I / F (2a) to be switched to may be either in the same base station (a base station having a plurality of RF-I / Fs) or different base stations.
(B) In the terminal state notification / sharing phase, (A) the base station (1) acquires the terminal state related to the terminal (3) from the radio interface (RF-I / F) (1a), and (B) the base station Notify (2). The base station (2) that has received the terminal state uses the terminal state for (C) the RF-I / F (2a) that is the connection switching destination of the terminal, Performs forced association / authentication processing. At this time, the base station (2) performs the above process internally without any communication with the terminal.
On the other hand, it is confirmed that the terminal (3) is actually performing data communication with the base station (2) and that the broadcast key (Group Transient Key (GTK)) is notified from the base station (2). When 4) is confirmed, the relay node instructs the base station (1) to delete the terminal state information of the terminal (4), and the base station (1) notifies the terminal at the wireless MAC layer. Perform a forced disconnection process.
The relay node (wired node) (4) temporarily stores (buffers) data destined for the terminal (3) and completes the association / authentication procedure during the terminal state notification / sharing phase It is also possible to cancel the storage and release the stored data together.
A packet destined for the terminal (3) is detected by capturing the packet header.
By synchronizing the terminal state in the base station (1) of the connection source and the terminal state in the base station (2) of the switching destination, data is continuously transmitted from the base station (1) during the notification of the terminal state. The CCMP packet number and WPA sequence number in (1) are prevented from being preceded.
As a result, data loss at the time of handover can be prevented.

The base station (2) may be the same frequency channel as the base station (1) or a different frequency channel.
When the base station (2) is activated with a different frequency channel, it is necessary to notify the terminal of a new channel. For the channel change notification, a probe response frame is used, and the channel switch assignment (CSA) field in the Vender Specific field of the packet is used to send the switching destination RF− to the terminal. Notifies the frequency channel of the I / F.
However, when the handover destination base station is activated on the same frequency channel, the channel change notification is not necessary.
(C) After the temporary buffering of data is stopped on the relay node, the data addressed to the terminal may be multipath-transmitted so as to pass through both the base station (1) and the base station (2). .
The effect of multipath transmission is minimization of frame loss when switching frequency channels in the radio interface of the terminal. Since the base station (1) and the base station (2) transmit the same data, the terminal (3) receives from the base station (1) up to a certain frame and from the base station (2) from the next frame. An effect is obtained that handover between base stations without frame loss can be performed smoothly without strict time synchronization in units of frames.
When the relay node has the OpenFlow function, it can be realized by the OpenFlow packet duplication function and the output port selection function for each flow.
Here, when different communication channels are used in the communication between the terminal and the base station 1 or the base station 2, a channel change instruction is issued to the base station 1 and the terminal, and the wired node Send channel change completion notification to Also, a terminal connection completion notification is sent from the base station 2 to the wired node. The H / O destination base station may have the same frequency as the H / O source base station or a different frequency.
(D) As a procedure for stopping transmission / reception of the base station 1, a broadcast key update instruction is issued from the wired node to the base station 2. This enables a group key handshake between the base station 2 and the terminal. When receiving the broadcast key update completion notification, the wired node issues a disconnection instruction to the base station 1, that is, a terminal state deletion instruction. As a result, the multipath transmission is completed, and the terminal only performs communication with the base station 2 thereafter.
(E) As a handover completion process, the duplicate data detection discard using the terminal as the transmission source is terminated.
This makes it possible to switch the RF-I / F of the base station used for data transmission / reception without disconnecting the connectivity of the data link layer between the terminal and the base station.

In (a) handover preparation phase and (e) handover completion processing phase, duplicate data detection / discarding with the handover terminal as the transmission source is operated at the same frequency by the base station (1) and the base station (2). Run if.
In the above case, after the association / authentication process in the base station (2) is completed, both the base station (1) and the base station (2) can receive the data frame transmitted by the terminal, and these base stations receive the received frame. To the wired network. The same packet is duplicated in the wired network. The relay node captures the source IP address or source MAC address field and performs a duplicate check.

  A wireless LAN base station and a relay node having all the above functions were developed, and when two base stations were operated on different frequency channels, the time required for handover was actually measured.

Specifically, from (1) “buffering of data addressed to H / O terminal” in the handover preparation processing phase to (4) “data transmission to H / O terminal in the H / O source base station transmission / reception stop phase” The time until "end of multi-pass transmission" was measured. The measurement result was about 100 milliseconds on average, excluding the effects of the timer immediately after “buffering data destined for H / O terminal” and the timer immediately after “channel change instruction” (both 100 milliseconds).
However, the terminal only slightly increased the packet reception interval when the channel was changed, and was able to execute handover between base stations without making the user aware of it.

  The present invention can also be applied to a virtual inter-base station handover. Here, the virtualization compatible base station is a base station having a function of constructing a virtual radio interface (vRF-I / F) in the base station. First, the basic items will be described below. Here, the reason that one side is a wired network is to make the explanation easy to understand. Alternatively, a wireless network connecting relay nodes may be used.

  First, the wired / wireless integrated network is composed of a wired network section (entrance link section and core network section) and a wireless access section, and resource use in each section is integrated based on user service requests recognized within the network. It is defined as a network that is constructed by controlling dynamically and dynamically.

  That is, the mobile network corresponds to a wired / wireless integrated network, the wired network section corresponds to a virtual network that can form a virtual network, and the virtual wireless network corresponds to a wireless access section.

  Mobile network virtualization is the virtual construction of a logical mobile network on a common physical mobile network by realizing the characteristic functionality of resource separation and programmability in each section using network virtualization technology. It is. At this time, based on the technology (service awareness technology) that recognizes and identifies the service usage status of mobile users in the network, it dynamically secures network resources for important services that should be prioritized, and a new virtual mobile network Assign.

  An overall view of the wired / wireless integrated network is shown in FIG. Each virtualization compatible base station is accommodated in a virtualization compatible base station accommodating switch (vBS-SW) serving as a gateway to the core network. Here, a model in which one base station has multiple wireless IFs and supports different types of wireless access, a model in which multiple base stations with different wireless access methods are accommodated by one vBS-SW, and a macro cell It assumes a general-purpose mobile network model including heterogeneous networks that contain both microcells and microcells.

  In mobile network virtualization, as shown in FIG. 1, in order to provide a specific service on a dedicated mobile network (that is, a virtual network) virtually constructed without making the user aware of it, it is common for all services first. After defining a virtual network (that is, a common slice), and if necessary, constructing a new virtual network (that is, a new slice) that is specialized for a specific service, then changing the network that provides the service from the common slice to the new slice Handover (that is, handover between virtual networks) is performed.

  FIG. 2 shows a procedure for newly constructing a virtual network and a handover between virtual networks. As shown in Fig. 1, the components of the mobile network virtualization system assumed in this paper are vBS (virtual base station), vBS-SW (virtual base station accommodating switch), virtual network (NW) ) Control server, application server, and terminal.

  The functions that characterize this system are related to vBS (that is, a virtual base station corresponding to a virtual network), virtual network control, and radio IF (interface) control of vBS-SW.

  The main point here is that after introducing the virtual radio interface (vRF-IF) in the vBS, the vBS-SW collectively controls the change of the route from the application server to the vRF-IF in the vBS due to handover between virtual networks In the point.

  The important point is that when viewed from the wired network side, handover between virtual networks can be regarded as switching of virtual wireless IF in vBS.

Using WiFi as a case study, we will describe the construction of a specific new virtual network in the following assumed environment, and means for realizing handover between virtual networks. However, the following handover procedure can be applied to other radio access methods and service requirements.
First, the wireless access method is limited to WiFi, and the base station has a plurality of WiFi interfaces. Further, it is assumed that the service requirement of the priority service is the minimum bandwidth.

  Here, consider the case where a new virtual network construction decision is made after the service is started (new construction based on measurement results). It is assumed that the common virtual network has been constructed.

・ Activation and registration of priority service (on common virtual network)
The service provider (application (APP) server) establishes a connection with the common virtual network via a virtualization compatible node that is an access GW to the common virtual network.
The service provider pre-registers priority service information in vBS-SW. Here, the priority service is assumed to be agreed in advance based on the service content.
The priority service information is composed of flow information and service quality requirements.
The flow information includes a flow whose source or destination is the service provider (APP server). For a client-server service, [source address = IP address of APP server, destination address = ANY (optional) ), Port number = port number for the service] (APP server-> recipient), or [source address = ANY (optional), destination address = IP address of the APP server, port number = port number for the service] ( (Recipient-> APP server).
It is possible to prioritize only the flow of a specific terminal among the flows transmitted and received by the APP server. In that case, the above “ANY (arbitrary)” portion may be replaced with the IP address of each user, the network address of the subnet to which each user is connected, or the like.
On the other hand, the service quality requirement is a necessary minimum bandwidth. (Depending on the characteristics of the service, requirements such as maximum delay and maximum packet loss rate may be considered.)
At this time, a service providing form using a plurality of APP servers or a plurality of IP addresses may be used.
The vBS-SW holds the priority service information in the “service registration / filter unit”.

  As a method of registering services in vBS-SW, in addition to the method of explicitly registering services from the server to vBS-SW as described above, a list of services that vBS-SW should provide in advance as a virtual network is provided. The method of holding, the method of registration by a third party other than the service providing server based on the network usage, etc., vBS-SW itself recognizes the service based on the traffic pattern, protocol pattern, header, payload information, etc There are several possible methods, such as registering with.

・ Start priority service (on common virtual network)
Based on the registered priority service information, the service provider starts a service providing program on the APP server, and enables server access from the service receiver on the common virtual network.
At this timing, priority service data starts to flow on the common virtual network.

・ Quality measurement of common services on common virtual network (on common virtual network)
On the common virtual network, quality measurement is performed periodically (for example, every minute) to check whether the priority service meets the service quality requirement.
For services that require the minimum bandwidth, passive measurement is used to calculate the throughput in units of flow from the amount of data actually transmitted / received at the receiver after the service data transmission / reception has started between the APP server and the receiver. I do. Active measurement using a packet for measurement such as Packet Pair can be performed between the APP server and the receiver. Measurement results are first collected by the APP server.
For a service that requires a maximum delay, the round trip delay can be measured using Ping (SNMP Request message) from the APP server to each recipient, or Ping from each recipient to the server. For services that require a maximum packet loss rate, measurement burst data of a certain size can be measured by transmitting and receiving between the APP server and a specific receiver.
The measurement result is notified to vBS-SW from the APP server that acquired the measurement data.

・ Necessity determination of priority virtual network
vBS-SW requires a priority virtual network for the priority service when the above measurement results do not satisfy the quality of service requirements for all or a certain percentage of the priority flow (s). It is judged that. The virtual network construction / management department in vBS-SW is in charge.

・ Calculation of resources allocated to the priority virtual network
The virtual network construction / management unit in vBS-SW performs the calculation. However, the virtual network construction / management unit may be on an external server that can communicate with the vBS-SW.
The vBS-SW determines the initial value of the allocated resource for the new virtual network so as to satisfy the service quality requirement.
Specifically, in a service that requires the minimum bandwidth (R) for each user, the bandwidth required by the product of the minimum bandwidth and the assumed number of users (addition of parameters that further anticipate the statistical multiplexing effect) is calculated. .
In the core network, when the standard route does not satisfy the service quality requirement, an appropriate virtual network topology (network configuration, route) is determined.
In the radio access network, the radio access method to be used and the corresponding radio IF setting are determined so as to satisfy the service quality requirement. In the case of WiFi, specifically, the channel setting in the wireless IF at the handover destination and the ratio of resources allocated to the virtual network among the wireless IF resources are performed.
In order for the terminal to recognize the virtual radio IF of the handover destination, the priority virtual network ID (VN-ID) corresponding to the virtual radio IF one-to-one is determined. In the case of WiFi, EEID and ESSID can be used as VN-ID.

  With respect to the amount of resources allocated to each virtual network in the virtualized wireless network, the resource allocation ratio to each virtual network in the virtualized network is set to the same ratio, or the absolute amount of resources allocated to each virtual network in the virtualized network (for example, Various allocation policies such as allocation of the same resources as the network bandwidth) can be adopted.

-Notification of priority virtual network configuration and allocated resources
vBS-SW notifies each vBS of the above-mentioned priority virtual network configuration, allocated resources, and priority service information.
At the same time, the same information is notified to the virtual network control server in the core network or the virtualization-compatible wired node.

-Virtual network construction in the core network.
In the core network, based on the above notification regarding the priority service, the route table of the virtualized wired node and the traffic control parameters for the priority service flow are set.

・ Virtual network construction in wireless access network.
In the radio access network, the traffic control parameters for the vBS-SW routing table and the priority service flow are set based on the above notification regarding the priority service.

-Setting of radio IF of base station In the radio access network, the radio IF of vBS is set based on the above notification regarding the priority service.
Specifically, a frequency to be used, a ratio of base station resources to be used, and the like are set.

・ Initial quality measurement in priority virtual network (optional)
Same as “Measurement of quality of priority service in common virtual network”.
However, since the APP server and the receiver are still connected to the common virtual network at this point, the measurement is performed not between the APP server and the receiver but between the virtualization-compatible wired node and the vBS.

-Check for excess / deficiency of allocated resources (optional)
After adding a certain amount of resources, the same processing as the above-mentioned “notification of configuration of priority virtual network and allocated resources” is performed. It is also possible to execute it repeatedly periodically until the excess or deficiency is resolved.

-Inter-virtual network handover The vBS wireless IF setting is changed so that the terminal switches the connection from the vBS wireless IF corresponding to the common virtual network to the vBS wireless IF corresponding to the priority virtual network.
Specifically, the terminal is forcibly disconnected by de-auth or the like, and access control is performed so that the terminal cannot access the wireless IF.
At the same time, access control is performed so that the wireless IF at the switching destination can be accessed from the terminal concerned.
When the terminal includes a plurality of wireless IFs, the terminal tries connection with each wireless IF in order or simultaneously.
Priority service resumed.
The process is the same as the “priority service start”, and the server access from the terminal can be accepted on the new virtual network.

-Quality measurement of priority service in priority virtual network The same processing as the above "initial quality measurement in priority virtual network" is performed.

  At the end of the service, the corresponding virtual NW is erased by instructing each node constituting the virtual NW to release the network resources being used in the same procedure as the construction of the new virtual NW.

  According to the service definition described above, even for traffic transmitted from the same server, individual flows may be transmitted separately for a plurality of virtual networks for each importance. In this case, in order not to make the server aware of switching of the virtual network for each flow, the gateway that accommodates the server in the virtual network (a type of node that configures the virtual network and has the virtual network function) Is the switching point for virtualized networks. In the section between the server and the gateway, a virtual line is set by the same method as the virtual network.

  A network configuration in which a plurality of vBS-SWs are connected to the core network is also conceivable. In that case, the master vBS-SW is determined using information such as the network configuration, the access pattern to the server, the load status of each vBS-SW, etc., and the master vBS-SW information among all the vBS-SWs. Synchronize between vBS-SW by sharing.

  Next, the function of the virtual base station (vBS) and the method for realizing the virtual wireless IF (virtual wireless data transmission / reception circuit) will be described with reference to FIG.

Each section of vBS-SW in FIG. 3 has the following functions.
Virtual NW construction / management section: Determines NW resource allocation and NW configuration (topology) in each section for the virtual NW.
The above information is notified to the virtual network control server on the core network.
Switching device controller: Centralized control of switching settings (association) of programmable switching devices in vBS-SW and vBS.
Manages connections between vBS-SW or virtual wireless IF (virtual base station) built in vBS and each wired IF.
Wireless IF control unit: Centrally manages the settings of each wireless IF of vBS.
Virtual NW H / O control function: Determines the appropriate radio IF for connection to each terminal and instructs terminal IF switching.
Service registration / filter function: Service information is acquired from the service provider (application server). Determine whether the service should be prioritized.
Programmable switch (see below)

Each section of the vBS in FIG. 4 has the following functions.
Wireless IF (transmission / reception unit): Sends and receives wireless signals including data and control information to and from wireless terminals.
Virtual wireless IF (virtual wireless data transmission / reception circuit): A wireless data transmission / reception circuit that is logically divided or grouped together, independent of the wireless data transmission / reception circuit (wireless IF).
Wired IF (transmission / reception unit): Sends / receives signals including data and control information to / from vBS-SW.
Programmable switcher: For each data frame received from the wired IF, the wireless IF used for transmission is switched in frame units.
For each data frame received from the wireless IF, the wired IF or wireless IF used for transmission is switched in frame units.
(Constructs a virtual wireless IF in the switcher)
It is also possible to extract only the priority service flow.
Wireless IF management unit: Manages the setting information of each wireless IF based on the instruction from vBS-SW, and sets the wireless IF.

・ Definition and realization method of virtual wireless IF (virtual wireless data transmission / reception circuit) Physical that enables access to wireless resources divided and abstracted by wireless IF (wireless data transmission / reception circuit) by time axis / frequency axis / space axis Wireless IF (≈physical AP / base station).
A virtual radio IF (virtual radio data transmission / reception circuit) is an independent logical radio IF that can be provided to a mobile user by a plurality of physical radio IFs. ≒ Virtual AP / Base station)
The virtual wireless IF has a one-to-one correspondence with the virtual NW.
The presence of the physical RF-IF is hidden from the virtual radio IF user, and it appears that there is only a specific virtual RF-IF that can be accessed (including the virtual RF-IF for the common virtual NW).
The data frame is switched between the virtual wireless IF and the wired IF by the programmable switch based on the path control separately specified from the vSB-SW (built-in OpenFlow controller function).
The logical division of the wireless IF is realized by division on the time axis / frequency axis / space axis.
The logical integration of the wireless IF is realized by link aggregation, channel bonding, coordinated transmission technology (CoMP) between base stations in the LTE system, and the like.

・ Virtualization compatible base station (vBS):
Connected to vBS-SW by wired link (entrance link).
The data frame is switched between the virtual wireless IF and the wired IF by the programmable switch based on the path control separately specified from the vSB-SW (built-in OpenFlow controller function).
The wireless IF management unit is a function for setting a physical / virtual wireless IF in response to an instruction from the vBS-SW wireless IF control unit.
In addition, the wireless IF management unit also receives instructions from the vBS-SW inter-virtual network handover control unit, so that the terminal can switch the virtual radio IF (inter-virtual network handover), such as access control based on the MAC address. Set up.
It has a measurement unit and can measure the usage status (transmission / reception data amount, etc.) of the wireless IF and the wired IF.

  In the vBS configuration described above, there is no limitation on the means for transferring a signal (data) input / output from the wireless IF of the virtual base station to the virtual base station accommodating switch. In other words, any one of transfer as a radio signal (L1 transmission), transfer as a MAC frame (L2 transmission), or termination of IP at the base station (L3 transmission) may be used.

  Regarding the virtual radio IF, a configuration in which the same configuration as that of the virtual radio base station is also introduced into the terminal is possible. In that case, the virtual wireless IF in the terminal is logically connected to the virtual wireless IF constructed in the virtualization compatible base station. In order to construct a virtual circuit between the virtual radio IFs, a link is actually established between the available radio IFs of the terminal and the base station based on an instruction from the vBS-SW.

・ Virtualization-capable base station accommodation switch (vBS-SW):
It has an important controller function to manage the entire virtual network on the mobile network.
In addition to the handover between virtual networks, it also has a role to secure the interconnection between the wired network section and the wireless network section of the virtual network.
All users connected to the base stations to be accommodated are stored as a list.
The characteristic functions are as follows.
1. Service registration / identification, service filtering 2. Virtual NW control of wired section Virtual NW control for wireless section (vBS virtual IF control)
4). Handover control between virtual networks

Next, a method for realizing handover between virtual networks (radio access part) will be described.
As a method for providing the inter-virtual NW handover means to the terminal, several realizing means are conceivable.
First, the vBS-SW explicitly notifies the terminal of information related to the handover destination NW (NW-ID, etc.).
Next, dynamically change the access control settings in the physical radio IF of the vBS (rejection of connection to the physical radio IF of the handover source, permission of connection to the physical radio IF of the handover destination), and force the already established connection Using the disconnection as a trigger and using the base station automatic search / connection function of the terminal, the connection to the physical radio IF of the handover destination is guided.

Next, a method for realizing handover between virtual networks (in the case of OpenFlow) will be described with reference to FIGS. 4 and 5.
One way to implement a programmable switch is to use OpenFlow. In this case, the vBS-SW and each vBS operate as an OpenFlow switch (OF-SW). The OpenFlow controller function is vBS-SW, and all base stations accommodated therein are centrally managed.
FIG. 4 shows an example of connection between vBS-SW and each vBS when an OpenFlow switch is used as a programmable switch.

Next, a method for realizing handover between virtual networks (in the case of OpenFlow), in particular, handover between logically divided virtual radio IFs will be described with reference to FIG.
The inter-virtual network handover is switching of the virtual wireless IF. It supports both inter-base station handover and intra-base station handover models, and OpenFlow controls traffic path changes between virtual radio IFs accompanying handover.

  FIG. 5 shows a specific example of handover between virtual networks by OpenFlow. In this example, the virtual radio IF corresponding to a specific service is switched from vRF-IF ¥ # 11 of vBS ¥ # 1 to vRF-FI ¥ # 21 of vBS ¥ # 2. At this time, the flow table of the vBS-SW is updated, and the traffic is switched from vBS ¥ # 1 to vBS ¥ # 2. On the other hand, the flow table is similarly updated in vBS ¥ # 1 and vBS ¥ # 2, and a new flow ID1 entry is added in the handover destination vBS ¥ # 2. As the vBS setting is changed, the receiving terminal of the service switches the connection-destination base station from vBS ¥ # 1 to vBS ¥ # 2, thereby completing the inter-virtual network handover.

  When performing a handover between virtual NWs across physical wireless IFs, a virtual wireless IF connected to the handover source virtual NW is replaced with a physical wireless IF that provides a virtual wireless IF connected to the handover target virtual NW. Before switching the virtual circuit, the virtual NW traffic of the handover source is duplicated by the vBS-SW through which it is passed and simultaneously transferred to the two virtual wireless IFs. Seamless handover with no data loss during switching is possible.

Next, embodiments relating to the claims of the present invention will be described. Here, the virtual wireless IF and the wireless IF are referred to as vRF-I / F and RF-I / F, respectively.
The vRF-I / F shown below is a bridge module that connects a wired interface and one or more wireless interfaces (RF-I / F) in a base station. The feature of vRF-I / F is that one vRF-I / F is constructed for one or more RF-I / Fs regardless of the physical RF-I / F configuration. The vRF-I / F is constructed in one-to-one correspondence with the virtual NW (service dedicated slice) in the base station. That is, at the base station, one or more RF-I / Fs are assigned to one virtual NW. At this time, each RF-I / F may be the same wireless communication method or a different wireless communication method. A base station capable of constructing a vRF-I / F is referred to as a virtual base station (vBS). The vRF-I / F is connected to the wired I / F and the RF-I / F at the data link layer, and performs switching between these interfaces based on a routing table that associates the destination MAC address with the RF-I / F. Each entry in the routing table is generated by MAC address learning or forced addition / update from an external node.

  The vRF-I / F can be connected to a wired I / F or RF-I / F at the network layer. In this case, the vRF-I / F performs routing between these interfaces based on the destination IP address and the routing table that associates the RF-I / F.

  The vRF-I / F is constructed in a one-to-one correspondence with the virtual NW (service dedicated slice) in the base station. When the virtual NW includes a plurality of base stations, one vRF-I / F having the same vif-ID (described below) is constructed on each of the plurality of base stations.

  The vRF-I / F has a 12-bit unique identifier (GUID), which is a vRF-I / F ID (vif-ID). The vif-ID is generated by the mobile network operator who manages the base station using a hash function. The vRF-I / F has a 12-bit virtual BSS ID and a virtual ESS ID of up to 32 characters. Regarding the GUID, a size of 12 or more can be set.

The following functions can be given as characteristic functions of the vRF-I / F.
(1) A function of distributing data received from a wired I / F to a plurality of RF-I / Fs based on a routing table that associates a destination MAC address with an RF-I / F.
(2) At the start of connection with a base station (initial connection vRF-I / F) and at the time of handover between base stations, a mobile terminal (from a connectable RF-I / F to an arbitrary RF-I / F) Hereinafter, the function of connecting the terminal).
(3) A function of dynamically adding / deleting an RF-I / F constituting a vRF-I / F.
(4) For the wired NW (vBS-SW), information on the use status of the base station configured at least from the number of associations in the base station, the average transmission / reception rate, and the total PHY rate (standard value) of RF-I / F Provide function.
(5) State information such as CCMP pairwise transient key (CCMP pair temporary key), CCMP packet number, WPA sequence counter, capability information, etc. for each terminal in the base station to which the terminal is connected may be extracted and become a handover destination. A function to notify and share the predicted base station in advance.
(6) A function that, based on the notified terminal state, forcibly connects (association and authentication) processing at the wireless MAC layer to the terminal without completion of communication with the terminal.
(7) A function for forcing frequency switching notification to an arbitrary frequency among the frequencies that can be set by the terminal to an arbitrary terminal that is connected.
(8) A function of performing a forced disconnection (authentication stop) process in the wireless MAC layer for any connected terminal.

  Here, the vRF-I / F handover is a form of handover between base stations by switching the vRF-I / F to which the terminal is connected. Since the vRF-I / F is composed of one or more RF-I / Fs in the base station, the handover between the vRF-I / F naturally involves switching of the RF-I / F. Here, the handover destination vRF-I / F may be in the same base station or in a different base station.

FIG. 8 shows an outline of handover between base stations (bRF-I / F) handover in the case of a base station capable of configuring vRF-I / F. FIG. 8 shows an operation in which the terminal performs a handover from the vRF-I / F1 of the virtual base station (1) (vBS1) to the vRF-I / F2 of the virtual base station (2) (vBS2). The terminal state is not managed centrally by the entire base station, but is managed by the vRF-I / F in units of vRF-I / F.
In this example, in vBS1, vRF-I / F1 is composed of two RF-I / Fs, and in vBS2, RF-I / F1 is vRF-I / F1 and RF-I / F2 is vRF- Each I / F 2 is configured.

  FIG. 9 shows a software process configuration of the virtualization compatible base station (vBS) (10) capable of configuring the vRF-I / F that enables execution of handover between base stations (between vRF and I / F). The vBS (10) includes a vRF-I / F (10a), one or more RF-I / F (10b), a wired I / F (10e), a vRF-I / F management function (10c), and an RF-I. / F management function (10d). The vRF-I / F (10a) has an RF-I / F data distribution function (10f), and the data flow destined for the terminal that has performed the vRF-I / F handover is set as the destination MAC address. Based on this, switching is performed to the RF-I / F to which the terminal is actually connected.

  FIG. 10 shows an implementation example of vBS (11). The vBS is composed of four IEEE 802.11a / b / g / n compatible RF-I / F (12a), a CPU board (12) equipped with Linux (registered trademark), and an OpenFlow switch device (13). . After setting the same BSSID and ESSID for all RF-I / Fs, a unique virtual BSSID (vBSSID) and virtual ESSID (vESSID) were set for each vRF-I / F.

Further, in FIG. 11, in order to enable the terminal to identify the vRF-I / F, the vBSSID and the vESSID are notified to the terminal using the Vendor Specific (user identification) field of the beacon. vRF-I / F is
(1) vRF-I / F module that transmits / receives a frame to / from a wired I / F RAW socket,
(2) In-kernel TUN / TAP device (14i),
(3) Open vSwitch OVS (14c) bridge device that connects RF-I / F and TUN / TAP device and performs switching between RF-I / F of downstream flow at RF-I / F switching Configured. Trema (14b) was used as a common OpenFlow controller for Open vSwitch in vRF-I / F and OpenFlow switch device. The flow processing rule for the OpenFlow controller is a method in which the vBS-SW registers via the vBS controller (14a) based on the service identification function. The hostapd program (14d) was used for setting, management, and terminal authentication of multiple RF-I / Fs. Further, the individual notification of the change destination frequency to the H / O terminal is realized by using the CSA field of the management frame. On the other hand, the function for the terminal to acquire the vBSSID and vESSID from the Vendor Specific field of the beacon is implemented by modifying the iw command.

FIG. 12 shows an implementation example of the virtualization-compatible base station accommodation switch (vBS-SW) (11). The vBS-SW is (1) a vBS-SW control node unit including a vBS-SW controller (15b) mainly for setting and controlling vRF-I / F of each vBS and controlling inter-vRF-I / F handover of a terminal. (15a) and (2) an OpenFlow device unit (15c) that routes the data flow to each connected vBS based on the destination IP address.
When the base station to which the terminal is connected is switched due to the handover between the vRF-I / F, the OpenFlow switch apparatus of the vBS-SW temporarily stores data flows destined for the terminal, the handover source vBS and the handover Multipath transmission to the destination vBS, forcible route change to the handover destination vBS, and the like are performed.

From the viewpoint of inter-base station handover, the advantage of introducing vBS-SW in which vRF-I / F is introduced and vBS-SW that performs integrated control for multiple vBSs is that handover between base stations of a terminal with vBS-SW is determined. In doing so, it is not necessary to explicitly specify the handover destination base station or RF-I / F.
In the case of the base station that does not have the vRF-I / F shown in the first embodiment, the relay node grasps the usage status of each RF-I / F, and then determines each of the individual terminals. It was necessary to specify RF-I / F.
On the other hand, when vBS introduces vRF-I / F, vRF-I / F conceals the physical RF-I / F configuration in each vBS, so vBS-SW (corresponding to a relay node) is vRF- A handover destination may be selected in units of I / F. Furthermore, the vBS-SW can acquire information necessary for determining the handover destination such as the number of associations in the unit of vRF-I / F, the average throughput, and the sum of physical rates for each vRF-I / F.

  In addition, as a prediction method of a base station that is a handover destination, (1) the position (latitude and longitude) information of each vBS is acquired in advance, and the GPS information that the terminal has is periodically unicasted from the terminal. Obtain and predict the nearest vBS from the positional relationship between them. (2) Monitor data transmitted to the vBS to which the terminal is connected by a nearby vBS connected to the vBS and the network, A method such as confirming whether communication is possible can be considered. Information such as the number of vRF-I / F associations and average throughput is acquired from these vBSs, and the handover destination vBS is finally determined based on policies such as the smallest number of associations and the smallest average throughput. .

The vBS and vBS-SW described above were developed. In a configuration in which two vBSs having four RF-I / Fs are connected to the vBS-SW, the time required for the actual handover was measured.
Specifically, from (1) “buffering of data addressed to H / O terminal” in the handover preparation processing phase to (4) “data transmission to H / O terminal in the transmission / reception stop phase in the H / O source base station” The time until "end of multi-pass transmission" was measured. As a result of the measurement, an average of about 100 milliseconds was obtained excluding the influence of the timer immediately after “starting buffering of data addressed to the H / O terminal” and the timer immediately after “channel change instruction” (both 100 milliseconds).
However, the terminal only increased the average packet reception interval by several tens of milliseconds when the channel was changed, and was able to execute handover between base stations without making the user aware of it.

  For a multi-function WiFi base station that is assumed to be installed in an area where user concentration is expected, the method of the present invention can be applied by expanding, reducing, or parallelizing functions as necessary. .

1 Base station 1a RF-I / F
1b vRF-I / F
1c Wired I / F
2 Base station 2a RF-I / F
2b vRF-I / F
2c Wired I / F
3 Terminal 4 Relay node 10 vBS
10b RF-I / F
10c vRF-I / F management function 10d RF-I / F management function 10e Wired I / F
10f RF-I / F data distribution function 11 vBS
12 CPU board 12a RF-I / F
13 Open flow switch device

Claims (12)

In a wireless LAN system including a plurality of base stations, a mobile terminal, and a relay node in a communication network or a base station having a function corresponding to the relay node, from the first base station to which the mobile terminal is connected, In the inter-base station handover for switching the connection to the second base station,
(1) The relay node acquires terminal state information related to authentication and connection of the mobile terminal from information in the first base station to which any one of the mobile terminals is connected, and uses the acquired information as the second base station of the handover destination Notify the station in advance and share it,
(2) Using the notified terminal state information, the second base station executes a forced authentication / connection process in the wireless MAC layer for the mobile terminal, and executes an authentication / connection protocol with the terminal. Not by running internally,
(3) will receive a completion notice of the authentication and connection process of the relay node is the second base station (2), to start the multipath transmission for further disconnect instruction has been transmitted to the first base station, in Rukoto to receive the disconnection completion notification from the first base station, switching to the second base station to forward the data from the first base station to the mobile terminal as the destination, thereby completed the multipath transmission The mobile terminal only communicates with the second base station,
(4) The first base station performs a forced disconnection process in the wireless MAC layer for the mobile terminal being connected without executing a disconnection protocol with the terminal,
And a handover method between base stations.   The wireless LAN system according to claim 1 is a system that employs WPA2 and CCMP as an authentication method and an encryption method, respectively, and the terminal state information of (1) includes at least a CCMP pair temporary key. The inter-base station handover method according to claim 1.   3. The inter-base station handover method according to claim 1, wherein the terminal state information of (1) includes a CCMP pair temporary key and a CCMP packet number.   The inter-base station handover method according to any one of claims 1 to 3, wherein the terminal state information of (1) includes a CCMP pair temporary key, a CCMP packet number, and a WPA sequence counter. .   The terminal according to any one of claims 1 to 4, wherein the terminal state information of (1) includes a CCMP pair temporary key, a CCMP packet number, a WPA sequence counter, and capability information. Inter-station handover method.   The terminal state sharing method between the base stations is a method in which the first base station notifies and shares the second base station by broadcast communication or by unicast communication with the second base station as the destination. 6. The inter-base station handover method according to claim 1, wherein the inter-base station handover method is provided. further,
( 5 ) The second base station of (2) immediately before the relay node or the base station having a function corresponding to the relay node requests the terminal state information from the first base station of (1). The transmission of the packet addressed to the mobile terminal is temporarily interrupted and stored in a period from the reception of the notification of the completion of the authentication / connection processing to the mobile terminal. The inter-base station handover method as described in 1. above. Furthermore, when the frequency channel used by the second base station is different from the frequency channel used by the first base station,
( 6 ) Notification of forced switching to the frequency channel used by the second base station to the mobile terminal connected to the first base station, and the first base station to the terminal This is performed by unicasting a probe response frame in which the frequency channel is indicated in the announcement (CSA) field.
The inter-base station handover method according to any one of claims 1 to 7, characterized in that further,
( 7 ) After the authentication / connection processing in the second base station in (2) is completed, the relay node or the base station having a function corresponding to the relay node copies a packet addressed to the mobile terminal, The inter-base station handover method according to any one of claims 1 to 8, wherein each of them is simultaneously multipath-transmitted to the first base station and the second base station.   The inter-base station handover method according to any one of claims 1 to 9, wherein the relay node or the base station having a function corresponding to the relay node is a first base station. . The wireless LAN system is a network including a virtualization compatible base station, a virtualization compatible base station accommodating switch or a virtualization compatible base station having a function corresponding thereto, and a mobile terminal,
The virtualization-capable base station accommodating switch has a function of dynamically changing the amount of resource used in units of virtual networks,
The virtualization-capable base station is connected to the virtualization-capable base station accommodating switch using the virtualization-capable base station accommodating switch as a relay node, and has a function of dynamically changing the amount of resources used in a virtual network unit Is,
In handover between base stations for switching the connection from the first virtualization compatible base station to which the mobile terminal is connected to the second virtualization compatible base station,
(1v) In the first virtualization compatible base station to which any one of the mobile terminals is connected, terminal state information related to authentication and connection of the mobile terminal is acquired, and the acquired information is used as a handover destination for the second virtualization compatible Notify the base station in advance and share it,
(2v) The second virtualization compatible base station performs authentication / connection processing in the wireless MAC layer for the mobile terminal using the notified terminal state information,
(3v) The first virtualization compatible base station performs a disconnection process in the wireless MAC layer on the mobile terminal being connected,
The inter-base station handover method according to any one of claims 1 to 10, wherein a handover between virtualization compatible base stations is performed.   Further, when the relay node has an open flow switch function, the authentication / connection process is completed from the second base station in (2) immediately before requesting the terminal state information from the first base station in (1). During the period until the notification is received, the packet transmission is temporarily suspended by delaying the packet-in procedure of the OpenFlow and the response to the packet-in in the OpenFlow controller for all the packets addressed to the mobile terminal. The inter-base station handover method according to any one of claims 1 to 11, characterized by being interrupted and stored.

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