Research On Energy Balanced Transmission Strategy In Wireless Sensor Networks

With the rapid development of chip, communication and sensing technologies, wireless sensor network (WSN) has become the key technology in the new era of sensing technologies. In WSN, the tiny nodes, which consist of sensing, data processing and wireless communication components, are deployed densely and randomly in large numbers. The tiny nodes form the WSN in a self-organization manner. Based on the diverse onboard sensors, the WSN can sense the field and communicate the information to the remote sink in an efficient and timely manner. The sensing performance and reliability have been improved significantly in WSN. So the WSN can be widely used in military sensing, security, environmental monitoring, traffic surveillance, medical treatment, building and structures monitoring, even anti-terrorism, etc.Sensors in the wireless sensor networks usually have limited power and it is impractical to replace the batteries once the sensors have been deployed. A main goal in designing such WSNs is conserving energy so as to maximize the network lifetime. Unbalanced energy consumption is an inherent problem in wireless sensor networks where some nodes may be overused and die out early, resulting in a short network lifetime. There are two traditional transmission protocols: hop-by-hop and direct transmission. The thesis identifies the drawbacks of two transmission protocols which result in the unbalanced energy consumption of the sensors. As we know, clustering is one of the most efficient schemes for prolonging network lifetime. However, to achieve a better balance of energy consumption, the cluster-head selection algorithm must be performed frequently, which will add excessive processing and communication overheads to the network.The research work and innovation of the thesis are as follows:(1) The thesis analyzes the problem of the unbalanced energy consumption of the two traditional transmission protocols and proposes the energy balanced transmission strategy, including hybrid transmission strategy and rang-adjustable transmission strategy. The hybrid transmission strategy is mainly studied in the thesis and we make further study to improve the balance of the strategy. The simulation shows that the strategy better balances the energy consumption of the nodes and prolongs the network lifetime.(2)The thesis proposes an energy balanced transmission strategy for cluster-based wireless sensor networks. Simulations show that the network lifetime by this transmission approach extends about 1.5 times of that in single hop mode and 6.5 times of that in multi-hop mode. The thesis considers a cluster-based WSN, which is partitioned into a number of Voronoi cells. For a Voronoi cell, the paper presents an energy-balance transmission approach to balance the energy dissipation, by adjusting the ratio of data transmitted to the next hop and the cluster head directly. The approach avoids the processing and communication overheads incurred by cluster heads reelection.