Research On Wireless Location Method For Life Detection

China is a country prone to natural disasters,once earthquake and conflagration happened,tens of thousands people were buried in the ruins comprised of houses,generally,the area the disasters happened always could be referred,but the density of the buried people and the more explicit area information is known mostly.Most of the available rescue methods and localization systems always require specialized equipment,contributing to rescue measures could not be carried out quickly and effectively.With the booming development of information and technology,about 90% people in China possess smart phones and other smart equipment,and these devices are always scattered near or by the side of the survivors after earthquakes,in view of the above situation,wireless location method for urgent life detection is designed and achieved,which can search and localize the wireless smart equipment with WiFi,as a result the positions of the buried people could be determined indirectly,and the survivors could be rescued as soon as possible.This paper mainly conducted the research on wireless location method based on mobile phone in the ruins.Firstly,the characteristics of wireless channel under the ruins are studied.In the post Wenchuan earthquake ruins,some typical building types after earthquakes,such as inclined support type collapse,overturning collapse,cantilever collapse and composite collapse,have been chosen to measure the propagation feature of wireless signal on2.3-2.5GHz with the frequency sweeping,and the measured data has been analyzed by MATLAB,to obtain the ruins of the large scale attenuation parameter including the free space path loss and loss of materials.In the study of material penetration loss of the debris,the ferro-concrete and cement bricks,which is prone to block signals more seriously,were selected to analyze the attenuation of the signal we studied,and the analysises of the small scale attenuation characteristics including the average excess delay and the root mean square delay have been conducted,and the distribution of RMS delay spread has been analyzed according to the cumulative distribution function(CDF)of measured data and evaluated by Kolmogorov-Smirnov(KS)and Chi-square goodness-of-fit test,finally,the system MK propagation model was concluded for subsequent verification.Secondly,the wireless positioning life detection system based on the studied channel model under the ruins wasdesigned and achieved on the android.The system comprised two parts: client and server.The client mainly was responsible for filtering unnecessary mobile phones,WiFi network management,WiFi signal acquisition,filtering processing and storage and forwarding to the server.The server received the data from the client and quickly performed the node estimation to display the relative coordinates of the point to be measured.Finally,by testing the system in the actual environment,compared with the logarithmic model,the MK propagation model concluded in this paper can reduce the location error effectively and make rescue more quickly and efficiently.