Research On Key Localization Technologies In Wireless Sensor Network Syncretizing Radio Frequency Identification

With the increasing demand of localization,localization applications have been applied from military and national defense to the civilian field.As the means of acquiring location,localization technology plays a crucial role in localization applications.The Radio Frequency Identification(RFID)is a typical wireless identification technology,which is commonly used in warehousing and logistics,retail manufacturing and food traceability.However,the short communication range and cellular communications limit the further application of the RFID.The Wireless Sensor Network(WSN),which consists of lots of sensor nodes with self-organizing and multi-hop wireless communication,has been extensively applied to the fields of military,industrial monitoring,smart home and traffic management.But the WSN causes a waste of hardware,software and information resources when it is only used for localization.In view of the advantage and shortage of the WSN and RFID,the RFID is integrated into the WSN in this paper.The established WSN Syncretizing RFID(WSID)can not only exert the advantages of network self-organization and multi-hop communication,but also achieve the efficient identification and localization of a target with high precision,low energy consumption and low system cost.Hence,the WSID presents significant research value and is of great utilization potential.Based on the basic theory and localization technology of the WSID networks,the requirement of the localization in modern greenhouse environment,in indoor environment with obstacles distributed and in complex and changeable outdoor environment are analyzed.Then,the existing problems in localization by range-free methods,localization in sparse distributed network and localization in energy heterogeneous network are studied.Main contents are as follows:(1)The localization theory system of the WSID is established.Based on the current research on the integration of the WSN and RFID,the localization system structure,node structure,operating system,protocol stack,network characteristic,typical application and localization technology of the WSID are defined,studied,supplemented and improved.The performance of the range-based and range-free localization algorithms of the WSID is compared and evaluated.(2)The problems of the large estimated distance error and poor evaluation effect of fitness function of the Distance Vector-Hop(DV-Hop)algorithm is studied.The bat algorithm(BA)is applied to solve the multi-objective optimization problems in DV-Hop algorithm.Then,the BA based DV-Hop(BDVHop)algorithm and the improved BA based DV-Hop(IBDV-Hop)are proposed.In the BDV-Hop algorithm,optimized methods of the average hop distance,velocity of bat and feasible solution updating are introduced.In the IBDV-Hop algorithm,an improved strategy of fitness function is given and further optimization of the BDV-Hop algorithm are presented.Simulation experiment results show that the BDV-Hop and IBDV-Hop algorithms present high localization accuracy,low complexity and good convergence.In greenhouse environment,the BDV-Hop and IBDV-Hop algorithms also show better localization performance than other algorithms.(3)The non-localizable problem in sparse distributed network is studied.The Gaussian mixture model is established to train and predict the trajectory of a target.A collaborative and predictive localization algorithm(CPLA)and a Radio Signal Strength Indicator(RSSI)-based CPLA(RCPLA)are proposed.In the CPLA,the collaborative and predictive localization schemes for multiple anchor nodes locating situation,two-anchor nodes locating situation,one-anchor node locating situation and non-anchor node locating situation are designed to solve the non-localizable problems.In the RCPLA,the RSSI is used to narrow the residence area of the target,and methods are introduced to improve the accuracy of the CPLA.Simulation experiment results demonstrate that the CPLA and RCPLA achieve accurate localization of the target in sparse distributed network.The RCPLA shows high localization accuracy when the measures error is little,while the CPLA presents high localization when the measure error is large.In indoor environment,the localization accuracy of the CPLA and RCPLA is higher than other algorithms.(4)The problems of unbalanced energy consumption and short lifetime in energy heterogeneous network is studied.The signal attenuation model is analyzed and the multi-energy dissipation model of nodes is established.An energy-efficient distributed localization algorithm(EEDLA)is proposed.In consideration of the dissipated and residual energy of nodes and the connectivity and distribution of network,the weighted subnetworks formation strategy,distributed localization method,energy state management of nodes and the data integration and transmission strategy are given to reduce complexity,improve localization accuracy and decrease energy consumption of the EEDLA.Simulation experiment results show that the EEDLA performs high localization accuracy and balanced energy consumption.In outdoor environment,the localization performance of the EEDLA is better than other algorithms.