Ranging method

A method of ranging between a first and a second radio signal transceiver, the method comprising:

• receiving a first set of measurement results and a second set of measurement results, wherein:
• the first set of measurement results is acquired by the first radio signal transceiver using a first set of antennas based on signals transmitted from the second radio signal transceiver using a second set of antennas,
• the second set of measurement results is acquired by the second radio signal transceiver using the second set of antennas based on signals transmitted from the first radio signal transceiver using the first set of antennas,
• the first set of measurement results comprising, for each of a plurality of frequencies and each of a plurality of antenna combinations between the first set of antennas and the second set of antennas, a measurement pair of a phase value and a signal strength value, and
• the second set of measurement results comprising, for each of the plurality of frequencies and the plurality of antenna combinations, a phase value, or optionally, a measurement pair of a phase value and a signal strength value;
• calculating a preliminary estimate of a value proportional to a one-way frequency domain channel response for a frequency of the plurality of frequencies and for each of a first antenna combination and a second antenna combination of the plurality of antenna combinations based on:
• from the first set of measurement results, the measurement results for the frequency and the respective antenna combination, and,
• from the second set of measurement results, the phase value for the frequency and the respective antenna combination, or the measurement results for the frequency and the respective antenna combination;
• calculating a comparison value for the preliminary estimate for the frequency and for each of the first antenna combination and the second antenna combination based on, from one of the first set or the second set of measurement results, the phase value for the frequency and the respective antenna combination, or the measurement results for the frequency and the respective the antenna combination;
• determining, for the frequency and the first antenna combination, a corrected estimate of the value proportional to the one-way frequency domain channel response based on the preliminary estimate and the comparison value for the first antenna combination and the second antenna combination;
• and
• performing a ranging calculation between the first radio signal transceiver and the second radio signal transceiver based on a plurality of such corrected estimates.