OFDM Transmission for Time-Based Range Estimation

OFDM is proposed for time-based range estimation (TBRE) and analyzed with respect to its accuracy, both theoretically, in terms of its Cramer-Rao lower bound (CRLB), and practically, in terms of its maximum likelihood estimator (MLE). The CRLB for OFDM transmission is compared to that for pseudo-noise (PN) transmission, demonstrating a large performance gap in favour of OFDM. Moveover, the MLE for TBRE is compared to the commonly used MLE for channel estimation (CE), demonstrating a performance gap in favour of the MLE for TBRE. Finally, the CRLB for OFDM is compared to its corresponding MLE for TBRE, demonstrating a good agreement in performance except for the so-called ??threshold effect??, which is analyzed analytically in this letter.