LTE Multipath Mitigation for Positioning in Urban Environments

Mitigating multipath of cellular long-term evolution (LTE) signals for robust positioning in urban environments is considered. A computationally-efficient receiver, which uses a phase-locked loop (PLL)-aided delay-locked loop (DLL) to track the received LTE signals is presented. The DLL uses an orthogonal frequency division multiplexing (OFDM)–based discriminator function to estimate and track the time-of-arrival. The ranging error performance of the DLL in an additive white Gaussian noise (AWGN) channel is evaluated numerically. The effect of multipath on ranging error is analyzed, demonstrating robust multipath mitigation for high transmission LTE bandwidths. A coherent time integration approach is presented to reduce the pseudorange error. The proposed receiver is evaluated on a ground vehicle in an urban environment. Experimental results show a root mean squared-error (RMSE) of 3.17 m, a standard deviation of 1.06 m, and a maximum error of 6.58 m between the proposed LTE receiver and the GPS navigation solution over a 1.44 Km trajectory. The accuracy of the obtained pseudoranges with the proposed receiver is compared against two algorithms: estimation of signal parameters by rotational invariance techniques (ESPRIT) and EKAT (ESPRIT and Kalman filter).