A method for position determination based on carrier-phase measurements is disclosed. The method comprises receiving one or more downlink signals transmitted from a base station (BS) during a downlink period, wherein the downlink signals are modulated using a downlink carrier wave, measuring, during the downlink period, a first carrier phase associated with the downlink carrier wave, estimating, during an uplink period subsequent to the downlink period, an integer ambiguity (IA) change, and measuring, during a later downlink period subsequent to the uplink period, a second carrier phase based on the resolved first carrier phase and the estimated IA change.