Determining location of a receiver with a multi-subcarrier signal

A method for determining a location of a receiver using a multi-carrier signal, the method comprising:

• receiving a plurality of multiplexed multitone signals, each multiplexed multitone signal having subcarriers and modulated with a pseudo-random noise code and transmitted from a transmitter with a known location;
• determining a coarse estimate of a time of arrival of a set of subcarriers of the multiplexed multitone signals by adjusting the coarse estimate of the time of arrival of the set in accordance with a code correlation function;
• determining a precise estimate of the time of arrival of the set of subcarriers of the multitone signals by adjusting the precise time of arrival to align the slope of the subcarrier phases of the multitone signals in accordance with a phase correlation function and consistent with the coarse estimate of the time of arrival associated with the code correlation function;
• estimating the location of the receiver or estimated range between the receiver and the transmitter based on the precise estimate;
• identifying a multipath-impacted signal arising from the transmitted multitone signal, wherein the identifying is accomplished by evaluating a received amplitude of the at least one subcarrier of the multitone signal;
• and
• compensating with multipath phase compensation data for a multipath phase error in the at least one subcarrier phase associated with the multipath-impacted signal arising from the transmitted multitone signal;
• wherein the phase compensation data results in or comprises an adjustment to the estimated range based on a direct signal vector length of a direct path signal and a multipath-impacted signal vector length of a multipath-impacted signal that are determined through observed signals or observed signal vectors of the receiver, wherein the vector lengths are indicative of corresponding amplitudes of the observed signals.