A ranging method of an access terminal comprising receiving and analyzing UL-MAP/DL-MAP; selecting a given uplink sub-channel number and a symbol number from the UL_MAP when a ranging event is generated; requesting a ranging process by transmitting a CDMA code; receiving a ranging response message broadcasted from the access point; extracting a CDMA code, a sub-channel number, and a symbol number from the received ranging response message, comparing the extracted result and the stored ranging parameters, and adjusting transmission power, timing, and frequency offset on the basis of the extracted result or discarding the ranging response message; and terminating a ranging response message receipt operation.