Means for maintaining connectable access points owing to movement of a mobile station between cells in a wireless LAN system
First Claim
1. A wireless LAN system comprising two or more access points connected to a LAN, each access point having a slave-station management table for managing user station addresses that are under its supervision, and user stations connected to terminals for wirelessly sending and receiving signals to and from the access points, each of said user stations searching for a connectable access point for connection thereto as a new access point when said user station moves, connecting itself to a new access point that has been found, and subsequently sending signals to and receiving signals from the new access point, wherein each of said user stations comprises:
- search means for searching for a connectable access point, said searching being performed before connection to the connectable access point becomes necessary;
a master-station management table for holding the address of the connectable access point; and
master/user station connection control means for sending a connection request to the connectable access point having said address held in said master-station management table when connection to the new access point becomes necessary.
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Accused Products
Abstract
A mobile user station periodically searches for a connectable access point and stores the address of a connectable access point that has been found in a master-station management table. When the mobile user station moves from one cell to another under these conditions, the state of communication with the old access point deteriorates. When the state of communication with the old access point deteriorates to such a degree that it becomes necessary for the mobile user station to connect to a new access point, the mobile user station sends a connection request to the access point stored in the master-station management table and performs communication via the new access point. As a result, when connection to a new access point becomes necessary owing to movement of the mobile user station between cells, the changeover between access points can be performed quickly without searching for an access point.
200 Citations
27 Claims
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1. A wireless LAN system comprising two or more access points connected to a LAN, each access point having a slave-station management table for managing user station addresses that are under its supervision, and user stations connected to terminals for wirelessly sending and receiving signals to and from the access points, each of said user stations searching for a connectable access point for connection thereto as a new access point when said user station moves, connecting itself to a new access point that has been found, and subsequently sending signals to and receiving signals from the new access point, wherein each of said user stations comprises:
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search means for searching for a connectable access point, said searching being performed before connection to the connectable access point becomes necessary; a master-station management table for holding the address of the connectable access point; and master/user station connection control means for sending a connection request to the connectable access point having said address held in said master-station management table when connection to the new access point becomes necessary. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A user station in a wireless LAN system for wirelessly sending and receiving signals to and from access points connected to a LAN, searching for a connectable new access point when the user station moves, connecting itself to the new access point that has been found and subsequently sending signals to and receiving signals from the new access point, said user station comprising:
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means for searching for a connectable access point in advance; a master-station management table for holding the address of said connectable access point; master/user station connection control means for sending a connection request to the access point held in said master-station management table when connection to the new access point becomes necessary; means which, after connection to the new access point has been established, is for sending a transfer request frame to an old access point via the new access point so as to request that data, which is addressed to a mobile user station and accumulated in a buffer of said old access point, be transferred to said mobile user station; means for sending a disconnection request to the old access point via the new access point in response to reception of notification of completion of transfer of the data, addressed to the mobile user station, from the old access point; and means for sending notification that reception is possible to the new access point after notification of disconnection is received from the old access point.
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18. A access point in a wireless LAN system in which the access point is connected to a LAN for wirelessly sending and receiving signals to and from user stations that are under its supervision, said access point comprising:
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a slave-station management table for managing addresses of user stations that are under supervision; connection control means for establishing a connection between the access point itself and a mobile user station in response to a connection request from said mobile user station; means for writing the address of the mobile user station that issued the connection request in said slave-station management table; means which, after connection between the mobile user station and the access point itself is established, relays to the mobile user station only those frames from a previously prevailing access point that are among frames addressed to said mobile user station and discards other frames addressed to said mobile user station; means for performing relay control of a control frame between the mobile user station and the previously access point; and means for relaying all frames, which are addressed to the mobile user station, after reception of notification that reception is possible sent from the mobile user station following cutting of a communication path to the previously prevailing access point. - View Dependent Claims (19)
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20. A wireless LAN system comprising access points connected to the LAN and user stations connected to terminals for wirelessly sending and receiving signals to and from the access points, wherein each access point comprises:
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a non-accessing terminal address table for storing the address of a non-accessing terminal to which power is being supplied from a power supply but which is not accessing the LAN; a master address table for registering the addresses of all terminals, which are the object of retrieval, in the non-accessing state; means for successively transmitting a request frame, which includes an address stored in said master address table as an address of a destination terminal, to user stations that are under supervision; and means for receiving a response frame which is sent from a user station in response to the request frame when the destination terminal is being supplied with power from a power supply but is not accessing the LAN, and registering the address of said destination terminal in the non-accessing terminal address table; and means for transferring the contents of said non-accessing terminal address table to a server connected to the LAN in response to a request of said server. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. A wireless LAN system comprising access points connected to the LAN, each access point having a user station absence/presence management table for managing absence/presence of user stations that are under supervision, and user stations connected to terminals for wirelessly sending and receiving signals to and from the access points, wherein the access point comprises:
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a non-accessing terminal address table for storing the address of a non-accessing terminal to which power is being supplied from a power supply but which is not accessing the LAN; a master address table for registering the addresses of all terminals, which are the object of retrieval, in the non-accessing state; means for successively transmitting a request frame, which includes an address stored in said master address table as an address of a destination terminal, to user stations that are under supervision; means which, when the user station has transmitted a response frame in response to the request frame because the destination terminal is being supplied with power from a power supply but is not accessing the LAN, is for receiving the response frame and registering the address of said destination terminal in said non-accessing terminal address table; and means for deleting the address of said destination terminal from said non-accessing terminal address table if a response frame in answer to said request frame is not received; and means for transferring contents of said non-accessing terminal address table to a server connected to the LAN in response to a request of said server.
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Specification