Optimizing Handoff Delay In WLAN

Continuous connectivity is one of the important requirements of Institute of Electrical and Electronics Engineers (IEEE) 802.11 Wireless Local Area Networks (WLAN) which allows user's mobility while utilizing the network. Consequently, many handoffs may occur as the mobile station (STA) is moving while accessing the network resources located at the distribution system side. The handoff originally associated from base station to another base station in the WLAN networks would affect the performance of multimedia applications which is sensitive to delay such as voice and video. This research proposed a new mechanism called Active Selective Context Caching (ASCC) which is able to reduce the delay of the re-association phase by eliminating the extra time consumed by the Inter Access Point Protocol (in order to transfer the context information of a ST A from the old AP to the new associated AP). This elimination can be achieved by transferring the context information of a ST A reactively from the old AP to the new AP prior to the re-association phase (during the discovery phase). The simulation's results show that by using the ASCC mechanism, the re-association delay can be reduced from an average of 27ms (in regular IEEE 802.11 handoff mechanism using conventional lAPP) to an average of 1.6ms (using ASCC) which is an improvement of - 94% of the total re-association delay