The present invention relates to a method for establishing a communication link between a mobile station and a wireless local area network LAN; and, more particularly, to a method for effectively selecting an access point AP by considering state information of access points in order to obtain maximum performance of data transmission in a mobile station for using high-speed wireless internet services.
Recently, a mobile service provider provides a high speed wireless internet service at a HOT-SPOT area by using a conventional wireless local area network LAN technology, which is introduced for wireless data communication within an indoor place. Registered users can receive the high speed Internet service after authorizing user's registered identification ID. For receiving the high speed Internet service, it requires an association step for selecting one of available access points and establishing a communication link between a mobile station and the selected access point based on IEEE 802.11. Conventionally, an access point having strongest receiving sensitivity is selected and the mobile station receives the high speed Internet service from the selected access point.
However, a performance of data transmission of mobile station may be incredibly decreased according to the number of users receiving the high speed Internet service in identical HOT SPOT area and an amount of traffic processed at the access point. Therefore, if the access point is selected by only considering the receiving sensitivity of the access point, the maximum performance of the mobile station can not be guaranteed. Also, it is not effective method for selecting the access point in a view of the service provider for managing entire network.
In other words, the mobile station of the user can not be guaranteed to have maximum data transmission speed defined in a wireless LAN standard of IEEE 802.11 in a HOT SPOT area where in a carrier sense multiple access/collision avoidance is used as a media accessing method and a number of users are frequently moving such as a bus terminal, a exhibition place and conference hall. In the above mentioned case, the performance of the mobile station is suddenly decreased according to the number of users connected to the selected access point and the amount of traffic processed at the selected access point.
It is, therefore, an object of the present invention to provide a method for effectively selecting an access point by considering state information including the number of mobile stations connected in each access point and a traffic amount at each access point.
It is another object of the present invention to provide a method for effectively selecting an access point by using a Beacon frame or a Probe response message frame in media access control layer of wireless LAN accessing device based on IEEE 802.11.
It is still another object of the present invention to provide a method for effectively selecting an access point based on state information of access point in a Beacon frame or a Probe response message frame.
In accordance with an aspect of the present invention, there is provided a method for selecting access point among a plurality of access points in a wireless local area network environment to establish a physical channel between a mobile station and a wireless local area network, the method including the steps of: a) at each of plurality of access points, inserting a first state information of the access point about the number of connected mobile stations into a Beacon frame/Probe Response message frame of wireless local area network LAN media access control MAC layer; b) at each of plurality of the access points, the Beacon frame/Probe Response message frame of the first state information is transmitted to the mobile station; c) at each of plurality of the access points, inserting a second state information about a currently processed traffic amount into the Beacon frame/Probe Response message frame; d) at each of plurality of the access points, the Beacon frame/Probe Response message frame of the second state information is transmitted to the mobile station; and e) at the mobile station, selecting one of access points based on the first and second state information.
In accordance with an aspect of the present invention, there is also provided a computer readable recoding medium storing a set of instructions for executing a method of selecting access point among a plurality of access points in a wireless local area network environment to establish a physical channel between a mobile station and a wireless local area network, the method including the steps of: a) at each of plurality of access points, inserting a first state information of the access point about the number of connected mobile stations into a Beacon frame/Probe Response message frame of wireless local area network LAN media access control MAC layer; b) at each of plurality of the access points, the Beacon frame/Probe Response message frame of the first state information is transmitted to the mobile station; c) at each of plurality of the access points, inserting a second state information about a currently processed traffic amount into the Beacon frame/Probe Response message frame; d) at each of plurality of the access points, the Beacon frame/Probe Response message frame of the second state information is transmitted to the mobile station; and e) at the mobile station, selecting one of access points based on the first and second state information.
The above and other objects and features of the present invention will become better understood with regard to the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:
Hereinafter, a method for selecting an access point AP based on state information of access points according to the present invention will be described in more detail with reference to the accompanying drawings.
For receiving the high speed wireless Internet service based on the wireless LAN technology, a user installs a wireless LAN card into the mobile station 101 and receives a permission to receive the high speed wireless Internet service from the authorization server 105 managed by the mobile service provider 108 through one of the access points 102 which are connected to the Internet 104. After receiving the permission, the user can access to a server of the service provider 108. For providing the high speed wireless Internet service, a public wireless LAN service network is constructed with a plurality of access points AP 102 within a service area in which a number of users is gathered and connecting the access points 102 to the router 103 based on a dedicated line. Furthermore, the service provider 108 implements the DHCP server 106 for allocating internet protocol IP address to the mobile station 101 and the network management device 107.
In a conventional wireless LAN environment based on IEEE 802.11, one of access points having strongest receiving sensitivity is selected and the mobile station 101 of the user receives data by establishing a physical channel between the mobile station 101 and the selected access point 102.
However, the present invention selects one of the access points 102 by considering not only the receiving sensitivity but also the number of the mobile station connected to each access point and an amount of traffic processed at each access point for establishing the physical channel between the mobile station 101 and access point 102.
Referring to
At first, the mobile station needs to establish a physical channel to the access point based on IEEE 802.11 through an authorization step of the service provider. That is, the mobile station 212 passively or actively searches the access point when the mobile station 212 is powered on or the mobile station 212 enters a service area 210 of the access point 211. The mobile station 212 selects an access point by considering the receiving sensitivity of the access point and establishes the physical channel to the selected access point having strongest receiving sensitivity. In case of Roaming operation which the mobile station connected to the selected access point enters a service area of another access point, the mobile station establishes new physical channel to another access point by detecting decrease of receiving sensitivity of the previously selected access point through an AP re-association step.
That is, when the Roaming operation is invoked by the mobiles station 212 entering to the services area 220 or 230 of the access points 221 or 231, the mobile station detects decrease of receiving sensitivity of the access point 211 and establishes new physical channel to another access point by selecting another access point between the access points 221 and 231 through AP re-association step.
However, in the present invention, the access point is effectively selected by comparing state information of access points received from the access points in order to have the maximum performance of data transmission during initial association step and re-association step. The state information is includes not only the receiving sensitivity of the access points but also the number of mobile stations connected to the access point and the traffic amount of the access point.
Referring to
The mobile station compares the first and second state information of access points and selects one of access points which provides comparatively high data transmission performance to the mobile station at step 305. Reference for selecting access point may be alternative. However, lowest traffic amount currently processed and less number of mobile stations connected are preferable to set as a reference to select appropriate access point.
Referring to
Referring to
At first, the mobile station 501 transmits a Probe message to access points 502 and 503 having identical SSID value as “nespot” by searching each channel at physical layer. The access points 502 and 503 transmit a Probe response message by inserting a first state information about the number of mobile station connected and a second state information about the traffic amount in the Probe response message.
The mobile station 501 compares the first and second state information in the probe response messages of the access points 502 and 503 and selects appropriate access points between the access points 502 and 503. If the access point 502 is selected, the mobile station transmits a request message for establishing the physical channel. If the access pint 502 receives the request message, the physical channel is established.
In the present invention, the first state information about the number of mobile stations connected to an access point and the second stat information about the traffic amount processed at the access point are inserted into a capability information region of the Beacon frame, which represents media accessing information broadcasted to mobile stations in passive AP searching method at MAC layer based on IEEE 802.11.
Referring to
In the present invention, the reserved region 604 is used as an AP capability region 604 representing the first or second state information of corresponding access point. Among 8 bits of the AP capability region 604, the first bit is used as an indication bit 605 and remained 7 bits are used as amount bits 606. That is, if the indication bit is “0” in binary number, it represents the first state information. That is, the AP capability region 604 contains information about the number of mobile station connected to the access point. The amount bits 606 contains the number of mobile stations connected to the access point in binary number form. If the indication bit is “1” in binary format, the AP capability region 604 contains the second state information about the amount of traffic processed at a port of MAC of access point.
The Probe message frame 701 is transmitted to access points in an active AP searching method in a wireless LAN environment based on IEEE 802.11. The present invention uses a capability information region of the Probe Response message frame to represent the first and second state information of the access point.
Referring to
That is, if the indication bit 705 is “0” in binary number, the AP capability region 704 contains the first state information about the number of mobile station connected to an access point. Accordingly, the amount bits 706 contains the number of the mobile stations connected to the access point in binary number. If the indication bit 705 is “1” in binary number, the AP capability region 704 includes the second state information about the traffic amount and the amount bits 706 contains a binary number representing the amount of traffic processed at the access point.
Referring to
As mentioned above, in the present invention, an AP searching step between a passive type and active type is distinguished and state information of access point are transmitted to the mobile station by inserting the first and second state information into the Beacon frame or the Probe Response message frame, respectively. The mobile station compares the first and second state information of access points and selects appropriate access point based on the state information of access points including the receiving sensitivity, the number of mobiles station connected to the access point and the traffic amount.
The present invention can be implemented as a software program which can be stored at a computer readable recoding medium such as a CD-ROM, RAM, ROM, floppy disk, hard disk and optical magnetic disk.
As mentioned above, in the present invention, the mobile station can have the maximum performance of transmitting data by effectively selecting access point based on state information of access points about an receiving sensitivity, the number of mobile stations connected to each access point and the traffic amount of each access point included in a Beacon frame and a Probe response message frame.
The present application contains subject matter related to Korean patent application No. KR 2003-0054588, filed in the Korean patent office on Aug. 7, 2003, the entire contents of which being incorporated herein by reference.
While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
Number | Date | Country | Kind |
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2003-54588 | Aug 2003 | KR | national |