Patent ID: 8665695

Claim:
A communications apparatus in a communications system, comprising: a receiving module, receiving a signal with a predetermined signal bandwidth, wherein the signal comprises a plurality of regular sub-carrier frequency components and a plurality of guard sub-carrier frequency components, and the signal carries data on both the regular and the guard sub-carrier frequency components; a low pass filter, filtering the signal to obtain a filtered signal, wherein a filter bandwidth of the low pass filter is wide enough to pass the regular sub-carrier frequency components and at least half of the guard sub-carrier frequency components of the signal; an analog to digital converter (ADC), sampling the filtered signal with a sampling rate exceeding a standard sampling rate defined in accordance with the predetermined signal bandwidth of the signal to obtain a plurality of digital samples; a Fast Fourier Transform (FFT) module, performing a fast Fourier transform on a predetermined number of points of the digital samples to obtain a plurality of transformed samples, wherein the predetermined number exceeds a standard number defined in accordance with the predetermined carrier bandwidth; and a sub-carrier collector, collecting the data from the transformed samples.