A Pre-registered Handoff Scheme in IEEE 802.11r Wireless Local Area Networks

Nowadays, with the wide establishment of IEEE 802.11, more and more people use Wi-Fi to surf on the Internet. Due to the convenience and mobility of the mobile devices, a number of mobile users have been increasing greatly. For real-time video and VOIP have attracted much attention, the delay time of handoff is the most important issue for the service. In order to provide high-speed service with low delay, IEEE 802 family defines the standard IEEE 802.11r to reduce the delay time of services. Due to IEEE 802.11r will expect that all AP has exchanged secure keys, which will reduce handoff delay time but will cause the authenticated information increment, a method is proposed. This paper executes pre-register with several specific AP to reduce exchanged secure keys. First, APs are divided into four regions according to RSSI. Second, the faster the mobile device moves, the less probable it is to change the direction suddenly and the region in front of the mobile device is more concentrative. Finally, after predicting the user number that all APs serve, the AP that serves the fewest people is selected. With the above three suggestions in this algorithm, IEEE 802.11r not only executes fast handoff, but also avoids too many authenticated messages.