Research On Energy-efficient Transmission Schemes For Wireless Sensor Networks Base On Cooperative MIMO

Wireless sensor networks(WSN) is a new technology of information access andprocessing, which has aroused the attention of many researchers for its greatprospect. It consists of a large number of tiny sensor nodes that contain sensor unit,data processing unit and communication unit and so on. Generally speaking, thebatteries of those nodes cannot timely be replaced or charged. Thus, how to design ahighly efficient energy transmission strategy becomes a key problem in WSN.Cooperative Multiple-Input Multiple-Output(MIMO) is an emerging energyefficient technology inWSN, which selects multiple sensor nodes with a singleantenna to act as transmitting/receiving antennas and form a virtual antenna array totransmit information.On the basis of previous studies, we have done the following researches for theproblems above.(1)The cooperative nodes selecting: in the middle-size and small-size intensivewireless sensor networks, the distance among nodes is very short and the channelsare not entirely orthogonal. Thus we should consider the channel orthogonal whichis an important factor effecting the cooperative transmission. A Network LifetimeMaximization-aware cooperative nodes selection algorithm is proposed in the article.In this algorithm, not only residual energy and SNR are considered, but also channelorthogonal condition which has emerged as an alternative to cooperativetransmission. Simulation results show that when compared with cooperative nodesselection algorithms with respect to channel gain and Leach algorithm, this newalgorithm has prolonged the network lifetime respectively, and significantlyimproves the survival rate of the nodes.(2)Research on multi-hop transmission strategy: the strategy proposed in thisarticle is based on multi-hop cooperative transmission model that widely apply inpractical applications; WSN has been divided based on geographic information, thenumber of clusters of each round associated with the probability of the number ofsurvival nodes; the strategy uses the cooperative nodes selection algorithmabove-mentioned; establishes routing tables in the cluster heads and selects theminimum energy path as a multi-hop routing. Simulation results show that compared to Leach protocol, this new strategy has prolonged the network lifetime andsignificantly improves the network performance.(3)Existing cooperative MIMO-based transmission strategies for WSN pay toomuch attention on how to save energy and how to increase the network lifetime.However，the data rate isn’t considered almost. In this article，the data rate, the powerand the lifetime of WSN are analyzed firstly, and then we propose a multi-objectiveevolution algorithm based on those objectives. In NSGA-Ⅱ, we select thepopulation by using the binary tournament firstly, then using single point selectionand dynamic mutation rate to evolve the population. At last, for the purpose of thebest distribution of the population, we use the Minimum Spanning Tree (MST)algorithm. The simulation results show that our algorithm is better than aggregatingfunctions on the network lifetime, and also give some parameter values that canreach good balance between the three objectives. Moreover, the results can give aneffective guidance for engineering applications.