Impact of IR-UWB waveform distortion on NLOS localization system

A large absolute bandwidth of UWB pulse offers high resolution localization system with improved ranging accuracy and the probability of go through obstacles. However, in completely non-line-of-sight (NLOS) environment, the impulse radio (IR) signal will undergo deeply waveform distortion due to frequency dispersion, which cause inaccuracy in peak position detection in correlation receiver, consequently result in ranging error in time based localization system. Although IR frequency dependence has already been addressed in aspect of channel modeling, in this paper, the influences of material frequency properties and IR propagation distortion on completely NLOS localization system performance are taken into account through frequency domain method. The successive internal reflection model is introduced to the process of IR transmitted through obstacles in indoor environment, with the electrical characteristics of different materials, the pulse distortions are compared in time domain using inverse fast Fourier transform (IFFT). The NLOS ranging errors caused by both pulse distortion and geometric configuration are derived in a simple way. Numerical results shown that larger variations of material electrical parameters in UWB bandwidth lead to greater pulse waveform distortion and propagation loss in obstacles, which can considerably decline the ranging accuracy.