A Proxy Based Solution to Address the Unsuccessful Handover Occurrence in 6LoWPAN-WSN

The handover (HO) process in mobile networks mainly comprises layer 2 (L2) disconnection of the mobile node (MN) at previous link, registration with new network and delivery of packets in the new domain. In order to reduce the registration time, several solutions based on pre-registration have been proposed where the MN can initiate and complete the registration process well before the L2 handover. However, in some mobility scenarios with high mobility speed (e.g. vehicular mobility models), the pre-registration is not always possible to achieve the successful HO process, thus the result is failed or unsuccessful-HO. Therefore, in this paper we first articulate the problem by analyzing the issues responsible for the unsuccessful-HO followed by its theoretical analysis. On the basis of observations, we propose a mobility scheme that utilizes the link quality and mobility speed to trigger the HO process earlier for high mobility speed and vice versa. Due to the speed estimation we are able to categorize the HO into successful or unsuccessful one at the initial stage of HO process, thus reducing the delay operations to some extent. Furthermore, the gateway routers assisting mobility maintain a list of neighboring ANs which helps in HO triggering and establishing a bidirectional tunnel between Previous Gateway Router (PGR) and New Gateway Router (NGR) if the unsuccessful-HO occurs. To test the effectiveness, the proposed scheme is analyzed and evaluated by using the Network Simulator-2 (NS2). The handover performance is observed in two phases with respect to the variations in Wireless Link Delay (WLD) and Data Rate at different values of MN speed (v). The performance parameters namely HO delay, packet loss and signaling cost were observed. The data result shows that the proposed scheme improves the handover performance by reducing the HO-delay and packet loss to 15.1ms and 4% respectively. The proposed scheme also outperforms some of the highly cited solution in the field.