A method, an apparatus, and a computer program product for wireless communication are provided in which a set of time intervals is obtained from a received radio frequency signal. A power profile is determined for a frequency spectrum segment in each time interval. A first list is used to identify frequency spectrum segments that exhibit a power or energy profile over a range of frequencies associated with a downlink channel bandwidth, and a second list is used to identify frequency spectrum segments that have a total or average energy greater than a threshold energy relative to a noise floor. An absolute radio frequency channel number (ARFCN) of a wireless communication system is determined based on the time intervals identified in the first and second lists.