Research On Indoor Wireless Location Technology Based On UAB

Location is not only the natural attribute of human or object in the physical world,but also an indispensable basic information in the information world.High precision location information is very important for traffic alarm,first-aid service,battle scene command and control and other applications.It can greatly improve the social response ability to emergencies and improve people's lives.The technology and system of wireless location using the characteristic parameters of radio wave signal to estimate the coordinate position of a specific object in a certain reference system have developed rapidly,and based on ultra wideband(ultra Wideband(UWB)positioning has become an important means in the field of wireless positioning due to its advantages of ultra wide bandwidth,insensitivity to channel fading,low power spectral density of transmitted signal,high security,low system complexity and high positioning accuracy.It has attracted the attention of academia and industry.In the current UWB positioning system,the commonly used method is to measure the received signal strength indication(RSSI),time of arrival(TOA),time difference of arrival(of Arrival,TDOA)and other parameters,and then calculate the distance between the beacon node and the positioning terminal.However,due to the complex positioning environment and serious multipath interference,UWB positioning system is faced with the problems of rough characterization of traditional channel model,errors in toa measurement results and estimation accuracy.Aiming at the above problems,this paper first introduces the principle and method of wireless positioning,discusses the characteristics of several mainstream wireless positioning technology schemes,as well as the factors affecting positioning accuracy,such as channel multipath effect,channel non line of sight distance and beacon point density.Secondly,on the basis of wireless channel distance path loss model and smallscale fading model,an improved UWB model based on Saleh Valenzuela channel model is proposed,and the corresponding simulation algorithm is established to carry out simulation experiment analysis.In the indoor Los environment,the channel impulse response of the improved UWB model is closer to the measured data,and the fitting degree of indoor propagation characteristics is higher.Finally,the infrared ultra wideband system based on impulse radio(IR)and the commonly used TOA estimation methods are analyzed.Based on the construction of MB-OFDM ultra wideband system model,the toa estimator model based on the combination of correlation and energy detection is proposed.By compiling simulation algorithm,the simulation experiment analysis is carried out.The algorithm can achieve higher diversity gain,which is related to the number of subbands and channel Sub integration proportion.