With the rapid development of the network and the popularization of laptops, the requirements on mobile office is becoming higher and higher. The conventional wired local area network is limited by the layout, and the wires are easy to be damaged, bringing inconvenience to maintenance and capacity expansion, and also the relocation and movement of various nodes in the network are quite cumbersome. Therefore, a wireless local area network which is high efficient and convenient and flexible in networking emerges because of demand.
The wireless local area network (WLAN) is a product of the combination of computer networks and wireless communication technologies. It takes a wireless multi-access channel as the transmission media, carries out data interaction using electromagnetic waves, and achieves the function of the conventional wired local area networks. Currently, the American Institute of Electrical and Electronics Engineers (IEEE) 802.11 has become the standard of WLAN and obtains a great deal of application and support. WLAN at least has to include a wireless access point (AP), and AP provides service within a limited physical area (abbreviated as cell in the following); if a large area of service coverage is to be achieved, a plurality of APs need to be installed. Different APs provide service for different cells, and a plurality of APs achieve a large area of service coverage all together. In the WLAN, when the mobile terminal (MT) moves from a cell to another cell, i.e. “handover” occurs to MT, there will be the problem of how to keep continuous data transmission. In order to solve this problem, IEEE802.11 working committee established an IEEE802.11f research group in March 2000, which is responsible for the development and implementation of the Inter Access Point Protocol (IAPP).
As shown in FIG. 1, FIG. 1 is a schematic diagram of an MT handover scenario in the related art. In the figure, there are two APs: AP1 and AP2; two cells: area 1 and area 2; and one MT. In the related art, the handover procedure of the MT mainly includes: when the MT moves from the cell (area1) covered by AP1 service to the cell (area2) covered by AP2 service, the MT sends a reconnection request to AP2, which carries the media access control (MAC) address of AP1 to which the MT is previously connected; AP2 returns a reconnection acknowledgement to the MT, and then sends handover information to AP1; AP1 sends information about the MT to AP2 according to the handover information and queries the maintenance time of the connection with the MT, if the connection maintenance time is less than the handover suppression time, then AP1 sends a connection relief frame to the MT in the cell covered by its service and deletes the MT from the local service list, if the connection maintenance time is greater than the handover suppression time, then AP1 does not send the connection relief frame but only deletes the MT from the local service list; AP2 associates with the MT according to the information about the MT and allocates a key to the MT, which is shared in an extended service set (ESS); and the MT carries out data transmission with AP2 using this key.
The problems existing in the above solution of the related art at least include: when the MT hands over from a cell covered by AP1 service to a cell covered by AP2 service, AP2 has to re-certificate the MT and has to acquire the information about the MT from AP1 actively, which causes that the entire handover procedure needs longer time and consumes additional radio resources, greatly reducing the communication efficiency of WLAN; and the key allocated by AP2 to the MT is shared within the same ESS, significantly reducing communication security.