Research On Wireless Channel Sounding And Channel Modeling In Indoor Environment

With the widespread development of smart terminals and mobile internet technology. Communication activities with others occur in an indoor environment more and more frequently,which causes increasingly demand of the wireless communications quality. The characteristics of the wireless channel is obtained through channel sounding and channel modeling,which not only can act as reference basis for communication system design,but also can be one of the effective ways to improve the communication quality.Given the indoor environment between two laboratories,channel sounding method is designed,off-line parameter extraction algorithms and channel modeling problems are studied in this paper.In this article,the mechanism of radio wave propagation is firstly explained. Classification of channel model, which includes definition of path loss models,shadow fading model and small-scale fading model.At the same time,several empirical path loss models and tapped delay line model are given.The physical meaning of time and frequency dispersion parameters is highlighted.Secondly,the experiment environment is introduced,measuring system is made of hardware platform about USRP and software platform about GNU Radio.USRP N210 motherboard,RFX400 daughterboard and RFX2400 daughterboard are actually used in hardware system.The operating order about transmitter and the receiver are shown in graph.The information of multipath channel can be got by correlation theory.Different perfomance in correlation varies with different kinds of pseudo-random sequence,which can be judged by some laws.The comparison of M sequence and CAZAC sequence with correlation performance has done.Channel sounding program is based on sliding correlation theory and realized with CAZAC sequence.Channel sounding is carried out with different measure parameters(the length of the sounding sequence and carrier frequency both are different in the experiment)through the measurement system.The meaningful parameters are declared.Finally,the off-line processing about the received data is established.The start position determination algorithm of received signal frame,multipath threshold estimation algorithm,channel impulse response estimation algorithm,channel delay power spectrum estimation algorithm and the doppler power spectrum estimation algorithm are involved in the offline processing.The channel impulse response is acted as intermediate parameters,which is made up of continuous form in correlation peaks and discrete form.Power delay profile and doppler power spectrum are obtained from the the channel impulse response correspond with different measure parameters.The impact on channel parameters caused by different measurement parameters is also analyzed.The relations of each path delay and the corresponding amplitude are studied.Applying statistical methods,a tapped delay model with some extent reference is build for the indoor environment between two laboratories,which also can be compared with theoretical model.