In this paper, we propose a method for increasing the handover performance of the 802.11 link layer. The method reduces the number of scanning channels by referencing an AP map based on GPS. Also, by monitoring the SNRs of the mobile node and neighbor APs, it enables the handover to maintain a higher SNR than a given threshold. The experimental results establish that it has an average disconnection rate of 6.7% and an average SNR of 16.8dB. It is 8.1% lower rate and 42% higher SNR than the method that makes a handover to the nearest AP without considering SNR. Also, it is 4.1% lower rate and 26% higher SNR than the method used by MadWifi.