Research On Energy Efficiency Of Wireless Sensor Networks With Cooperative Diversity

Wireless Sensor Networks (WSN) is a self-organization network. It is composed of large amounts of sensor nodes through wireless communication. Because Wireless Sensor Network is generally deployed in very complex environment and meanwhile sensor batteries are energy-constrained and difficult to replace, energy efficiency is a principle issue. To reduce energy consumption, cooperative diversity technology based on Multiple-Input Multiple-Output (MIMO) is introduced into WSN.Firstly, this paper summarizes characteristics of WSN and MIMO systems. Coding and decoding algorithms of Space-Time Block Code (STBC) and Vertical-Bell labs Layered Space-Time Code (V-BLAST) in MIMO are analyzed, and methods combined MIMO technology and WSN are presented.Then cooperative diversity technology based on STBC is studied. Propose system model of cooperative diversity at the receiver and STBC cooperation. By analyzing the circuit energy consumption and the transmission energy consumption of each sensor nodes, total energy consumption of the two cooperative models is presented, respectively. Influence of the number collaborative nodes number on total energy consumption is studied to get the optimal collaborative nodes number of the two model with different transmission distances. Results show that the optimal collaborative nodes number changes with various transmission distances. It also shows that the optimized STBC cooperation can save more energy for long-haul distances larger than a given threshold.At last, influence of constellation size on total energy consumption of local communication and long haul communication is presented, respectively. Optimal transmission scheme under different long-haul transmission distances is obtained by combing constellation size and the number of collaborative nodes. Simulation shows that optimal STBC cooperation can save more than 90% energy than traditional system.