Research On Handoff With Its Security Of WLAN

WLAN is a very important link way in the network connections, the good mobile ability is very suitable for the locations with large floating population such as airports, stations, schools and hotels…. In these locations, the users of WLC make the handoff in WLAN frequently, if the loads of the WLC points are not balanced, it wastes lots of WLC sources, so balancing the load of wireless access point and improving the using rate of the wireless and system performance has become one very important project in the research of WLAN. During handoff, it will cause some security problems, for example, illegal mobile terminal STA to AP to visit network and hold some network resources, in this way, mobile terminal STA visit illegal AP that it will cause information leakage…, so how to find a handoff system with high security and efficiency is one important project in the research of WLAN.In this text, firstly the author make a analysis on the handoff system of IEEE802.11 WLAN, and then make a detailed analysis all kinds of causes for the handoff delays on each stage, and make the analysis for some other problems caused during the handoff process.Then, the author make a detailed introduction on the security systems for WLAN and make the analysis on the advantage and disadvantage of the security systems in 802.11 WLAN.And then, based on the present handoff technology and security system of the WLAN and on the full analysis to security system and handoff technology of the WLAN, the author put forward a secure and fast handoff mechanism: when the user arrives in the superposition edge of multi-APs, make the mutual identity authentications to all abut APs between AP and users in advance, no need the server during the authentications so as to reduce the delay of the handoff; when there are multi-Aps to be choosed, in order to keep the load balance of Aps, combine with strength single and load also the AP size of spare bandwidth,rule is: in probably near to AP,if mobile terminal need bandwidth less than AP free bandwidth, then don't consider about AP. Or choose the AP with strongest signal but with the lightest load;if being above two the same load value and AP with medium single, so choose a target as AP in random. As far as possible can make assure each of AP in basic balance. At last, the author make a simulation experiment for the scheme, the analysis and result of the simulation experiment prove that this scheme has low switch delay and higher security,in this paper, and then against the load balancing distribution of the experimental programme, the experimental results show that the proposed allocation method in the overall performance is gooder than other distribution methods.