Quasi-Optimal Subcarrier Selection Dedicated for Localization With Multicarrier-Based Signals

The objective of this paper is to design dedicated probing signals for localization based on orthogonal multicarriers that attain the lowest value of the possible fundamental limits. The proposed scheme named Quasi-Optimal Subcarrier Selection (QOSS) attempts to generate the probing signals in positioning systems by minimizing the Cramer-Rao lower bound of range estimation in nonoverlapping multipath channels instead, which do indirectly depress the performance bounds in overlapping multipath channels to a certain extent. Based on the optimization of power allocation on orthogonal subcarriers, two kinds of QOSS signals are proposed for: 1) basestation (BS)-based localization networks where mobile station (MS) transmits to all BSs, and 2) MS-based localization networks where multiple BSs simultaneously transmit to the MS. Two adaptive search algorithms have been presented to generate the QOSS signal for MS-based localization networks. The fundamental limits of both QOSS signals are theoretically derived, the close relationship between the bound of range estimation and that of localization is disclosed and the lower bound of position dilution of precision is further obtained. Numerical results and experiments demonstrate our proposed theory.