Earticle

Link quality estimation (LQE) is an effective basic building block in wireless sensor networks (WSNs) and higher cross layer design of network protocol. Some researchers have investigated the statistical properties of the link quality estimators independently from higher-layer protocols, and their impact on the Collection Tree Routing Protocol (CTP). Then they set up a dedicated LQE, independent of the protocol interface, which has in total of four bits information: one from the physical layer, one from the link layer, and two from the network layer. Four-bit has been found to be a good estimator; however its performance heavily depends on the tuning of its parameters. But we found that Four-bit couldn’t be working effectively in responding to the burst situation after repeated experiments. So we redesigned the link estimation method, called Stable Link Quality Estimation (SLQE), which combines active probing with passive snooping to make estimation more stable. We have found that the new design can cope with the emergency. Moreover it also enhances the robustness of the network, and saves the overall energy consumption of the network.

In Wireless Sensor Networks (WSNs), as the network consists of low-cost sensor nodes with finite battery power, power efficient strategies must be applied for data transmission in order to prolong the lifetime of the network. It is important to minimize the total energy consumption in each round so that the network lifetime is maximized. In this study, we propose a new energy efficient protocol E-CTP based on the Collection Tree Protocol (CTP). Taking into account the power available to the whole network and single node, the Expected Transmission Value (ETX) was updated according to the proposed protocol. The related experiments were carried on TelosB, the results were compared in terms of lifetime and efficiency. We conclude that the new protocol has a longer lifetime and higher efficiency.