Research Of Key Technolugies On Reducing The Bit Error Rate Of Wireless Sensor Networks

With the development of sensor technology, wireless communication technology, network technology and micro-electromechanical systems, wireless sensor network has become one of the hot research topics in IT field, and has promising applications on areas like military defense, envi-ronmental monitoring, biomedical treatment and smart home. Currently, the reliability of data transmission is a challenge in wireless sensor net-work, thus this thesis researches on key technologies like coding tech-nology and nonlinear distortion cancellation technology to reduce the bit error bit and improve data transmission’s reliability in wireless sensor network. The paper’s study points have gained supports from the National Natural Science Foundation of China and the Fundamental Research Funds for the Central Universities, and have important research signific-ance and application prospects.On one hand, coding schemes suitable for wireless sensor network are designed with both considerations on data transmission’s reliability and system’s data requirements. With the development of wireless sensor network’s applications on various sub-systems, more flexible and higher rates are needed and the data requirement of smart home is just a typical example. In order to meet such requirements, this paper proposes to use the punctured convolutional code as the coding scheme to improve sys-tem’s reliability and reduce the bit error rate. Taking the searching com-plexity of exhaustive searching method into consideration, this paper presents a new good punctured convolutional code searching method based on quantum genetic algorithm to improve search speed and avoid local convergence. On the other hand, aiming at eliminating the adverse effects of white noise and nonlinear distortion caused by RF power amplifier and im-proving the reliability of wireless sensor network, this paper presents a new hybrid system of the fuzzy c-means clustering algorithm and adap-tive-two-stage linear approximation for the nonlinear distortion cancella-tion. This mechanism can eliminate the noise, adaptively model the PA’s instantaneous change, and then correct the nonlinear distortion efficiently.Finally, this paper designs a set of reliable multi-rate communication system for smart home scenario based on wireless sensor network which can meet flexible and high data rates requirements of different application systems and improve the system’s reliability and reduce the effect of non-linear distortion. The system uses the punctured convolutional codes searched in the second chapter as the encoding method, and then mod-ulates the encoded code and transmits them to the sending device. At the receiving device, the received signals firstly go through the nonlinear distortion cancellation module proposed in the third chapter to eliminate noise and nonlinear distortion, then are decoded through the demodula-tion joint decoding, i.e. sample, eight levels quantization, demodulation, and zeros pad-Viterbi decoding. According to the simulation, the result shows that this design can reduce the bit error rate of the received signal efficiently.