Mechanisms For Reliability And Energy Efficiency In Wireless Sensor Networks

With the rapid development of human society, Internet of Things (IoT) based on the com-munications of Human-to-Human, Human-to-Machine and Machine-to-Machine are gradually being realized. As an important foundation of Internet of Things, the technologies wireless sen-sor network have been focused on. the characteristics of the light-weighted computing, storage and communication ability in wireless sensor networks enable Quality of Service and energy efficiency hot research point. In order to meet the demands of the rapid development of Inter-net of Things, addressing the key issues of network Quality of Service and energy efficiency in wireless sensor networks, We analyze and summarize the technologies of the current extensive and efficient energy-saving technologies in wireless sensor networks in detail. To break through the key technologies of building efficient, reliable and energy-efficient wireless sensor networks, this thesis study a software-level and protocol in a deep manner.The contents in the thesis involve in overland wireless sensor networks and underwater wireless sensor networks, and distribute in the four protocol layers, which are physical layer, network layer, transport layer and application layer. Summarily, the main contributions and work in this thesis are:(1) An adaptive PA scheme for energy efficiency with QoS guarantee is proposed in WSNs. Firstly, we formulate the scheme as an optimization problem. We improve the PA-based scheme by an asynchronous waiting algorithm for event-driven communications based on delay-tolerant (DT) with priority to energy efficiency. And then we propose an adaptive waiting algorithm to improve the PA-based scheme for voice delivering based on delay-intolerant (DIT) with QoS guarantee. Furthermore, we analyze the performance theoretically. Finally, we conduct some simulations to evaluate the performance of these proposed solutions, comparing with the existing solutions in WSNs. The performance results show that this scheme outperforms the existing ones.(2) A novel Layered Multi-path Power Control (LMPC) scheme is proposed for reducing the energy consumption as well as enhancing reliable and robust communication in USNs. To this end, we first formalize an optimization problem to manage transmission power and control data rate across the whole network. The objective is to minimize energy consumption and simul-taneously guarantee the other performance metrics. After proving that this optimization problem is NP-complete, we solve the key problems of LMPC including establishment of the energy-efficient tree and management of energy distribution and further develop a heuristic algorithm to achieve the feasible solution of the optimization problem. Finally, the extensive simulation experiments are conducted to evaluate the network performance under different working condi-tions. The results reveal that the proposed LMPC scheme outperforms the existing mechanism significantly.(3) A novel Multiple-path Segment-based FEC (MS-FEC) mechanism with Hamming Coding is proposed for improving reliability and energy efficiency in USNs. A Markov Chain model is developed to formulate the probability of MS-FEC and calculate the overall PER for the proposed decision and feedback algorithm, which can reduce the number of the required multi-ple paths and guarantee the desirable overall PER in MS-FEC. Hence, this proposed mechanism is able to improve energy efficiency and enhance reliability for USNs. Compared to the tradi-tional multiple-path communication scheme, experimental results show that the proposed design achieves significantly shorter packet delay while consuming only 20%～30% of transmission energy in multiple-path USNs under various Bit Error Ratio (BER) of acoustic channels.(4) A new three-dimension localization strategy (3D-ARP) based on AOA, RSSI and water pressure is proposed.3D-ARP enables localizing all nodes in the networks straightforwardly where only one surface beacon node is deployed and non-linear least square method is employed to decrease measure error and non-line propagation error. The experimental simulation results show that 3D-ARP improves localization accuracy, localization duration and energy efficiency significantly, but also makes network setting easier.