Summary: This paper proposes a new method which simultaneously undertakes ranging and communications based on the PHY of MB-OFDM technology. A transmitter modulated one or multiple OFDM subcarriers with a low-frequency (1.05 MHz) ranging signal; and a receiver sampled the received signal at a 3.2-MHz sampling rate to estimate the time of arrival of the ranging signal. This configuration and an additional protocol supporting bidirectional ranging achieved a 140-mm resolution (equivalent to 2.15 GHz sampling). This method does not modify the PHY but only changes the baseband signal processing. The validity of this method was demonstrated using computer simulation and prototype experiments.