Patent ID: 8111661
Filing Date: 2012-02-07
Classification: H04B,H04L,H04W

Abstract:
1. A clear channel assessment (CCA) method implemented in an orthogonal frequency division multiplexing (OFDM) system, the method comprising: estimating first energy of a received signal in a first window of a predetermined interval of two moving-average windows and estimating a second energy in a second window of the two moving-average windows; detecting a peak value according to a difference of the first and the second energies, and counting a number of detected peak values; reporting a channel status to a medium access control (MAC) according to the number of the counted peak values; determining whether a period of time of reporting CCA has started, after counting the number of the detected peak values; comparing the number of the counted peak values with a predetermined critical value if the period of time of reporting the CCA has started; and establishing the channel status according to a result of the comparing, wherein the period of time of reporting the CCA repeats every 18 OFDM symbols, and corresponds to a period of time of at least one OFDM symbol for reporting the channel status to the MAC.