Research On Energy Efficiency Of Cooperative MIMO Technique In Wireless Sensor Networks

Wireless sensor networks have been widely used in a broad range of applicationareas, such as military, industry monitoring, environment monitoring and pricisionagriculture. In the most of its application scenarios, sensor nodes are powered by smallbatteries with limited energy, which are difficult or prohibitively expensive to rechargeor replace. Thus, improving energy efficiency has very important significance.Wirelesscommunication energy consumption is the main portion of energy consumption inWSN，through configuring multiple-antennas in transmitter and receiver, the MIMOtechnique could achieve diversity gain, multiplexing gain and interference management,which could significantly reduce energy consumption and improve energy efficiencyunder the same system performance requirements. However, due to the limitation ofcost, size and power, it is difficult to configure multiple-antennas for wireless sensornodes. Cooperative MIMO technique forms virtual antenna arrays by multiplesingle-antenna wireless sensor nodes, which could significantly reduce energyconsumption under the same system performance requirements. Therefore, thecooperative MIMO technique is regarded as a promising solution to improve energyefficiency and prolong the lifetime of WSN. However, taking cooperative MIMOtechnique to WSN still faces many problems: how to establish a precise transmissionenergy consumption mathematical model for cooperative MIMO, how to optimizecommunication parameters for cooperative MIMO transmission and how to design anenergy efficient cooperative MIMO transmission strategy for special applicationenvironment.The work in this paper has been supported by the National Science Foundation ofChina “Applied research on real-time monitoring of drilling engineering withcooperative MIMO in wireless sensor networks”(No.51174084).Improving energyefficiency as our primary purpose, we investigate the problem on how to optimizecommunication parameters for a single source cooperative MIMO transmission systemand how to design an energy efficient cooperative MISO transmission strategy. Themajor contents of this paper are as follows:1）Existing research on energy efficiency of cooperative MIMO technique in WSNmostly based on a fixed modulation scheme or a fixed number of cooperative nodes,without considering adaptive modulation or a variable number of nodes. To solve thisproblem, the problem of energy consumption optimization based on STBC, V-BLASTand cooperative beamforming for a single source node cooperative MIMO system in WSN was studied in this paper. Then, we propose a two-step optimization to minimizethe total energy consumption by optimizing the modulation parameters and the numberof cooperative nodes，the optimization reduce total energy consumption and improveenergy efficiency.2）Existing research on lifetime of cooperative MISO technique in WSN mostlybased on single-hop transmission scheme or multi-hop transmission scheme. Due to theuneven energy consumption of two clusters caused by solely cooperative MISOsingle-hop transmission scheme or cooperative MISO multi-hop transmission scheme,we propose a cooperative MISO based on hybrid transmission scheme which combineboth of the two schemes in this paper. Simulation results show that: cooperative MISObased on hybrid transmission scheme can effectively improve energy efficiency andextend lifetime of the network.