Study On Node Self-Localization Algorithms For Wireless Sensor Networks

As a new information capturing and processing technology, Wireless Sensor Networks can be wiedly applied in many application areas, such as battlefield surveillance,environment monitoring, space exploration, indoor user tracking and others. Many applications of WSNs depend on knowing the location of sensor nodes. Sensor data will lose its cost without corresponding spatiotemporal information. So, localization technology of sensor nodes in WSN is becoming a sustentation technology for WSNs, and attracts the attention of domestic and overseas scholars.Firstly, the research status of localization techniques for WSN is summarized based on the study of a lot of related literatures. The criterion of performance evaluation and algorithms, the taxonomy for wireless sensor networks localization systems are introduced in this thesis, the principles and characteristics of recent representative localization algorithms and systems are mainly summarized.Secondly, the thesis introduces a localization algorithm based on differential technology. There are two schemes based on differential technology, which utilize Hop Count and Hop Distance respectively. The detailed principle for differential-based localization algorithm and the difference between differential-based localization algorithm and non-differential algorithm are well studied. Simulation results show that the differential-based localization algorithm performs better than the non-differential algorithm. Using differential technology, the thesis proposed an improved DV-Hop localization algorithm which can reduce the location error accumulated over the multiple hops by making use of a differential error correction scheme. DV-Hop algorithm calculates the distance between node pair using the average hop size, which doesn't consider the speciality for each communication link. Based on the simulation, we compare the improved DV-Hop algorithm and conventional DV-Hop algorithm. Under the same conditions, the proposed algorithm can decrease the location error efficiently. Thirdly, the thesis proposed an improved centroid algorithm based on cooperative communication technology. The location accuracy and coverage of conventional centroid algorithm will be decreased with the decrease of anchor ratio, we can not increase anchor ratio since it will increase hardware cost. Thus, the thesis proposed to use cooperative partner to construct virtual anchor node and derive the calculation eqution for virtual anchor node. As can be seen from simulation results, the proposed cooperative localization algorithm has higher location accuracy and coverage than the conventional centroid algorithm.Finally, the work of this thesis is concluded and the future research work is presented.