دانلود رایگان مقاله تشخیص اهداف همراه انرژی کارآمد در حضور سینک های متحرک

Abstract

Tracking moving targets has become an increasingly important application for sensor networks. Sensor nodes may sense moving targets far away from the Source, and hence a large amount of energy may be wasted by them to send sensory data to the Source. Designing efficient algorithms and protocols for data dissemination to mobile sinks is an interesting research and engineering issue, especially for large-scale wireless sensor networks (WSNs). Sink mobility brings new challenges to the design of data dissemination. The location updates for each mobile sink need to be continuously propagated through the field to all sensor nodes, so that future data reports can be correctly delivered to the sink. As energy and resources of a sensor node are limited, these algorithms and protocols should meet a high energy efficiency and a high delivery ratio. To deal with this issue, we propose a framework, called Tree Overlay Grid (TOG), for data collection and dissemination. To route queries and deliver data efficiently in our framework, a geometric routing GFB (Greedy Forwarding within Bound) is proposed to create a TTDD-like grid network, and a tree protocol is used to construct local trees around sinks. In addition, two mechanisms are introduced to prolong the network lifetime. The first mechanism tries to save energy by reducing the traffic load; the second one tries to slow down energy consumption by balancing the traffic load. The simulation results show that TOG outperforms the best known data collection solution and some current data collection solutions for WSNs with multiple mobile sinks.

5. Conclusions and future studies

Mobility of target and sink brings challenges in WSNs. In particular, a target detection application needs a reliable data dissemination scheme. The previous solutions to target detection are inefficient due to skewed longer data dissemination paths, local query flooding, and new sources information flooding. Mobility makes them infeasible. In this study, we propose a novel data dissemination framework, which is called Tree Overlay Grid, to handle mobile target detections when multiple mobile sinks appear in wireless sensor networks. A grid network, which is built on top of the structure, helps distribute traffic flow along the grid line. Trees, which are constructed at the bottom grid cells, are used to collect information of mobile targets and sinks efficiently. In addition, two mechanisms are introduced to prolong the network lifetime. First, data aggregation is implemented to lower a traffic load to save energy. Second, four techniques are implemented to balance a traffic load to slow down energy consumption. The simulation results validate that our proposed framework consumes less total energy, performs well on the query and response work, and has a longer network lifetime among all. When collecting performance data by implementing TOG on real sensor nodes, we need to pay a special attention to batteries. Since batteries for sensor nodes are designed to run for years, it is not possible to implement TOG on real sensor nodes to measure the true network lifetime. As we all experienced, some batteries’ drain rates may be faster than others’ even though they operate under the exact same conditions. Nguyen et al. [32] pointed out that a sensor node with a half dead battery may still be able to transmit messages, but not be able to receive any messages. Based on the two facts above, the collected measurement data, especially for success ratios, may not be correct if the implemented network has included some nodes with such batteries.