A modified bumpless transfer technique for seamless handoff in mobile ad-hoc 802.15.4 wireless sensor networks

In this paper a modified anti-windup-bumpless-transfer (AWBT) power control technique is proposed, to enable seamless handoff in mobile ad-hoc wireless sensor networks, that are subject to hardware limitations. The approach adopts an intuitively appealing two step design procedure where firstly a linear controller is designed ignoring the inherent nonlinearities in the system. Quantitive feedback theory is used in this regard and provides pre-specified levels of robust stability and performance. In the second stage of the design process an AWBT controller is designed to account for hardware saturation constraints. This scheme is subsequently modified to account for feedback discrepancies due to a varying propagation environment, ensuring smooth handoff in the network. The proposed method is extensively tested on a fully compliant 802.15.4 wireless sensor testbed.