Research On Energy Efficiency Optimization Based On Cooperative MIMO In WSNs

Wireless Sensor Networks consist of a large number of miniature sensor nodes with the abilities of communication and computing, which deploy in unattended surveillance area to complete monitoring task through mutual cooperation and gather various object information to remote users, are intelligent monitoring network systems. WSNs have broad application prospect in many fields, and become a new study field in recent years. Sensors usually operate on battery which are difficult to recharge due to running in severe environment. Therefore, energy-constrained is a fundamental feature of WSNs which directly influences the lifetime of the network, so energy efficiency becomes one of the hot researches in WSNs.Recently proposed cooperative MIMO is an effective energy-saving technology of WSNs, which exploits individual single-antenna nodes to cooperate on information transmission and reception to resist multi-path fading, and realizes reliable communication with lower energy consumption. We mainly research on energy optimization problem based on cooperative MIMO for WSNs in order to improve energy efficiency and network lifetime.This thesis briefly describes cooperative related theoretical knowledge of WSNs, background and significance of the research, reviews current status at home and abroad, then especially investigates energy optimization problem based on cooperative MIMO and cooperation transmission scheme based on LEACH in detail. Firstly, the number of cooperative nodes and modulation rate are analyzed to impact on energy consumption of cooperative MIMO system. Then, an energy-efficiency adaptive transmission scheme is proposed for WSNs where energy consumption is the most important design criterion. A synthetic optimization of the number of antennas at both the transmission and the reception sides and modulation rate are selected with respect to the transmission distance to minimize the total energy consumption. Secondly, the cooperation transmission scheme based on LEACH is designed to configure different communication parameters (the number of cooperative nodes, modulation rate) according to the distance between cluster head to sink dynamically, the total energy consumption can meet minimum. At the same time, the maximum residual energy and minimum transmission power (MREMTP) collaboration nodes selection strategy is proposed to further save energy and balance energy consumption of networks. Lastly, with regard to two different distribution cases that nodes are sparse and dense, intra-cluster and inter-cluster collaboration schemes are designed to improve network lifetime effectively.