Robust range estimation in the presence of the non-line-of-sight error

The evolution to location-dependent services and applications in wireless systems continues to require the development of more accurate and reliable mobile positioning technologies. The major challenge to accurate location estimation is in creating techniques that yield acceptable performance when the direct path from the transmitter to the receiver is intermittently blocked. This is the non-line-of-sight (NLOS) problem, and it is known to be a major source of error in mobile location since it systematically causes the mobile to appear farther away from the base station than it actually is, thereby increasing the positioning error. We present a simple yet robust method for distinguishing between LOS and NLOS range measurements in a mixed measurement set and we validate its performance using simulations in several multipath channel environments.