A ranging method of an access terminal that requests a ranging to an access point through a wireless network and performs the ranging, the ranging method including a) initializing a ranging period, b) setting a timer with the ranging period and starting the timer, c) requesting a ranging by transmitting a given ranging code to the access point based on radio resource allocation information provided by the access point, d) receiving a ranging response message from the access point, and controlling transmission power, timing, and frequency offset of an access terminal according to transmission parameters included in the received ranging response message, e) estimating a downlink channel condition through which a signal from the access point is transmitted, f) resetting the ranging period according to the estimated downlink channel condition, and g) iteratively performing b) to f) according to the reset ranging period.