Design and Implementation of Location-Based Handoff Scheme for Multimedia Data

The handoff technology of the IEEE 802.11 refers to the process of transferring an Internet service from one channel connected to the Access Point (AP) to another. In order to provide mobility in wide area like port logistics, a handoff among APs is essential. However, the IEEE 802.11 handoff using hard-handoff may easily lose the connection and it wasters much time on recognizing the connection severance and channel search time for re-connection. In order to solve this problem, there have been several studies on the method of handoff prediction using (RSSI) Received Signal Strength Indication, moving pattern, multi-interface and Global Positioning System (GPS) technology. The handoff prediction methods that only consider one element compensate for the disadvantage of the legacy handoff method, but such handoff prediction methods still have problems. Especially, in case of a lot of mobile stations, the handoff prediction method using GPS causes a lot of data in GPS server and network. Then, if a mobile station handoffs only with distance or location information between APs, it is easy to cause a problem of frequent handoff in the border area. In order to solve such problems, we use GPS information to find out the location of the mobile station and predict the handoff point. Then, to guarantee the bandwidth, we propose the handoff algorithm using direction, velocity, and RSSI of the station. We implement the proposed handoff algorithm and evaluate its performance. As a result, we confirm the superiority of our algorithm by reducing disconnection time by about 3.7 ms. Our location-based handoff scheme improved the communication bandwidth by about 24 % more than that of location-based handoff.