Research Of Wireless Network Modulation Optimization Based On Energy Constraint

The Internet of Things(IOT)creatively implements the communication between objects and objects,which brings great convenience to human life.The Wireless sensor network technology(WSNs)has become a hot research topic as one of the IOT support technologies.WSNs is a network constructed by a large number of micro-sensors scattered in the monitoring area,which is used in military defense,biomedical,disaster relief,commercial application and so on.However,nodes are usually limited by the special geographical environment.Some of them can only use micro-battery and can't replace the battery in time.Therefore,reducing the unit energy consumption of nodes can greatly enhance the work time of the node,which has important effect on the development of wireless sensor network.This thesis proposes a modulation optimization scheme based on energy constraint to select the appropriate modulation order combined with the characteristics of small coverage radius and narrow working bandwidth.The research in this thesis are as follows:(1)The modulation and demodulation techniques in the communication system are analyzed and compared,and the comparison between single carrier and multi carrier is carried out.Based on the general model of communication system,the basic model of node wireless communication is simplified and the communication system model suitable for the research is obtained.Combined with the general structure of IF transceiver to establish a communication link model,and converted into energy constraints under the node energy consumption of the mathematical model.(2)The effects of the use of coding under energy constraints,the selection of modulation techniques,the selection of transmission distance,and the different modulation schemes on the modulation scheme are studied.Taking one hardware circuit of an industrial scientific medical band as an example,the thesis uses correlative parameters.The three different modulation techniques of MQAM,MPSK and MFSK are selected to establish the energy consumption model of unit bit information in Gaussian white noise channel respectively.Taking MQAM and MFSK as an example,the difference between the coded system and the uncoded system is compared,and the relationship between the transmission unit bit information energy consumption and the transmission distance and the modulation order is obtained through the simulation results.In addition,for the Rayleigh fading channel in wireless communication,the coded and the uncoded modulation optimization scheme are studied,and the experimental simulation and analysis are carried out under the given parameters.(3)Based on the above research,the modulation optimization scheme is extended to the multi-carrier system and the OFDM system is selected as the research object.The influence of the modulation order of the signal subcarrier on the high power amplifier is studied.The unit bit information energy consumption model of OFDM is established,and the simulation analysis.On the basis of previous studies,this thesis study the unit bit information energy consumption model of MIMO-OFDM,and the simulation analysis is carried out.