Mobile IPv6 function in the OPNET shows quite a long handover delay and lots of packet transmission errors. The reason is that relatively small-sized beacons can be successfully received in some border area where the longer data packets can not be transmitted because the longer in packet size, the higher in transmission error probability in wireless communication. New scan procedure will not start before a mobile node goes far away from the AP enough to occur the beacon reception error. In this paper, the modified WLAN simulation model is developed to improve the handover performance. In the developed WLAN model, new scan procedure starts when the number of beacons received successfully but with the power less than the designated threshold exceed the predefined threshold.