A smooth handoff scheme for real-time services in wireless LANs

Wireless LANs based on the IEEE 802.11 standard have become popular and widely used for mobile internet services, and Voice over IP (VoIP) is one of the most promising to be used in mobile devices over wireless networks. Up to date, many researches try to improve Wireless LAN system to provide higher data rate in order to support various kind of real-time applications such as VoIP. However, besides the need for higher data rates, smooth handoff is another important issue to be addressed in order to continue supporting real-time services across wireless LANs. In this paper, we proposed a Smooth Handoff Scheme that uses an Access Point (AP) Module with 2 transceivers in order to improve network efficiency in terms of supporting smooth handoff and avoid packet losses. In our proposed scheme, APs use the second transceiver to search for information of neighbor STAs in the transmission range by using a Passive Scan Mode, and later send the result back to associate AP, which in turn compare and analyze whether the STA should perform a handoff or not. The initial results from our simulations show that the proposed handoff scheme is more effective than conventional scheme in terms of latency and resource allocation control.