A method is disclosed for detecting packet at a receiving system in a Multi-Carrier Modulation (MCM) system. The method starts with receiving a signal at the receiving system. Then during the plurality of symbol durations, a set of phases of the signal for each symbol duration is obtained, where each phase is a phase of a carrier of the number of carriers. Then a set of phase variances for each carrier of the number of carriers is obtained, where each phase variance is a difference of phases of a carrier in different symbol durations. Then a phase variance value based on the set of phase variances is computed and it is compared with a threshold to determine whether a packet has been detected from the received signal.