Research On Indoor Ranging Method Based On Channel State Information

Nowadays,mobile wireless devices have fully integrated into people's lives,and various applications surrounding them are emerging endlessly.Outdoor wireless applications have basically achieved seamless experience under the support of cellular networks and GPS,but due to the lack of indoor GPS coverage,location-based wireless applications cannot be well implemented.The realization of accurate positioning services is inseparable from the stable and accurate distance measurement.This paper analyzed the related technologies involving wireless ranging and realized the indoor ranging by using the channel status information.Finally,experimental verification shows that the wireless ranging implementation method in this paper can meet the requirements of indoor environment ranging.Firstly,through the error analysis of commonly used wireless signal ranging methods,the common error sources of different ranging methods are found—shadow fading,and statistical characteristics of the test sample data are analyzed using statistical methods.On this basis,the linear relationship between ranging error and test distance is deduced based on the lognormal shadow model,and an online correction method for the normal shadow model is proposed by using this rule,which improves stability of the traditional wireless ranging method.In the stage of selecting wireless signal ranging means,by comparing the advantages and disadvantages between the channel state information and the received signal strength,the channel state information with finer granularity and good multi-path suppression characteristics is finally selected as the wireless ranging means of this article.And analyzed the feasibility of ranging as an indoor environment.The analysis shows that the channel state information of the wireless signal as a more comprehensive channel indicator can meet the ranging requirements in the indoor environment,and even can complete wireless applications that cannot be achieved by traditional ranging methods.The channel state information can reflect the amplitude and phase changes in the process of wireless signal propagation.Therefore,this paper uses these two parts of information respectively to make distance measurement attempts and builds a hardware test platform for channel state information acquisition and processing.Analyzing the measurement results,we found that using the wireless signal amplitude information measurement method can not avoid the shadow fading and multipath effect in the indoor environment.Although we can distinguish the line-of-sight path,we cannot remove the error caused by shadow fading,and finally The ranging result is equivalent to the traditional ranging method.On the premise of recognizing the line-of-sight path,the phase ranging method using multi-carrier technology adopts different ranging principles to avoid the influence of shadow fading.Experiments have proved that the phase ranging method can be stable and accurate.Ranging results to meet the indoor wireless application of ranging requirements.