Research Of Target Positioning Technology Based On Wireless Sensor Networks

Wireless sensor networks(WSN) technology is one of those who has deep implication tohuman’s future life. Position information is of great importance to WSN’s applications. To mostof the applications, data without target’s position information is no use. Dozens of targetpositioning algorithm based on WSN are born in practice, among which the time difference ofarrival(TDOA) technology is with higher positioning accuracy. Though this algorithm requireshigher hardware support, the hardware price goes down with technology develops, and TDOAtechnology is to with more application situations in the future. Therefore, this article focuses ontarget positioning algorithm based on TDOA technology, and mainly talks about the issue ofimproving positioning accuracy in non-ideal situations. In short, this article mainly about:1. With extensive reading of related articles, the WSN’s beacon nodes structure, networks’architecture, characteristics, researching backgrounds and researching status at home and abroadare generalized. The theoretical basis and development process of positioning algorithms aresummarized. The performance evaluation criteria and error representation of positioningalgorithm are showed. Introductions to several typical WSN target positioning algorithms andcontrasts to their performance indicators are provided.2. Introducing TDOA positioning algorithm and AF cooperative communication. Aiming atthe insufficient beacon nodes number of conventional TDOA positioning algorithm when appliedto bad channel environment, possible reasons are analyzed and improvement measures arepresent. AF cooperative communication technology is introduced to solve this problem. Whenchannel fades, cheap relay nodes using AF protocol to amplify and forward source signal areintroduced. These relay nodes become beacon nodes by broadcasting positioning signal to wholenet. The newly changed beacon nodes fulfill the demand of beacon nodes and recover WSN’spositioning ability.3. Since the factors affect positioning accuracy are not only related to beacon nodes but alsorelated to target source’s position change, researching aiming at the accuracy defect ofconventional trilateration-based TDOA positioning algorithm when target source is at theapproximately equal distance with beacon nodes are carried on. By analyzing the root of thisproblem, usual trilateration-based TDOA positioning algorithm is proved not to be appropriate tothis situation, and perpendicular-bisector-based TDOA algorithm is considered to be use. Tomeet the demand of positioning solving, using a preset threshold to filter TDOA data and selectappropriate beacon nodes to establish perpendicular bisector equations. The target position is to be solved by solving those perpendicular bisector equations4. A TDOA positioning algorithm based on AF cooperative communication as ChapterThree shows has been realized on personal computer. This algorithm helps to recover WSN’spositioning ability without adding beacon nodes number by broadcasting positioning signal towhole net, amplifying and forwarding the source signal using AF protocol.Finally, the thesis summarizes all the completed work and gives out the prospect of futureresearch.