A Mobility Based Link Layer Approach for Mobile Wireless Sensor Networks

Abstract

Several MAC protocols have been proposed forWireless Sensor Networks (WSNs). These include T-MAC , D-MAC and the more commonly utilized SMAC. In this paper, we propose a new MAC layer approach to support mobility in WSNs. The proposed technique utilizes an adaptive frame size approach to overcome the effect of frame losses caused by the Doppler shifts under mobile scenarios. An Extended Kalman Filter is used to predict the frame size for each transmission, which also directly enhances the energy efficiency of the system. Our results show that based on the adaptive frame size predictor and its comparison with the SMAC protocol, the proposed technique can improve overall system performance and deliver enhanced energy efficiency of 24% under mobility. The current implementation of ns-2 does not take into consideration the packet error rate. As another contribution of our work, we have developed a physical layer model for ns-2, which processes the received frame based not only on the fading characteristics of the signal but also the SNR and relative velocity between the nodes. To characterize a more accurate wireless sensor networks' physical layer, we have modeled the Mica-2 sensors in MATLAB and implemented the model in ns-2 for simulations.

A Wireless Sensor Network for RF-Based Indoor Localization

“…Raviraj et al [63] propose an adaptive frame size predictor to overcome the energy-inefficiency caused by frame losses in mobile scenarios. The approach can improve energy-efficiency by using smaller frame sizes when the wireless channel characteristics are poor.…”

On the Design of Mobility-Tolerant TDMA-Based Media Access Control (MAC) Protocol for Mobile Sensor Networks

“…In contrast, our approach does not rely on a localization service, and also does not depend on computing the 2-hop neighbourhood. Another strand of work focuses on tolerating bit errors that resulting from Doppler shifts, as a result of mobility [13]. This bit errors cause frame corruptions, and hence retransmissions that in turn deplete the energy resources of the system.…”