Abstract: A channel estimation apparatus and a method for the same are provided. The channel estimation apparatus includes a preamble buffer unit, a gain adjusting unit, a demodulation unit, and an estimation unit. The preamble buffer unit receives and temporarily stores a plurality of symbols in preamble signal. The symbols correspond to a plurality of gain control values. The gain adjusting unit adjusts the symbols to a plurality of gain normalized symbols according to the gain control values. The demodulation unit receives the gain normalized symbols and demodulates the same to obtain a frequency domain demodulation signal. The estimation unit receives the frequency domain demodulation signal and performs a channel estimation about the frequency domain demodulation signal and a frequency domain reference value of a standard preamble signal, so as to obtain a channel frequency response.

Abstract: An apparatus and a method for estimating noise power in frequency domain are provided. The apparatus and the method are applied to a state where no packet is transmitted over the channels. And the apparatus and the method acquire noise in every sub-carrier, and obtain the transmission status in every sub-channel to adjust bit-loading in every sub-carrier and improve the spectral-efficiency.

Abstract: A method for detecting a periodic signal in a communication system. The method includes converting a time domain digitized signal to obtain a corresponding frequency domain digitized signal, quantizing at least two symbols of the frequency domain digitized signal to obtain quantization information, utilizing the quantization information to compute a detection metric for periodic signal detection, and determining that a periodic signal is detected if the detection metric is greater than a predetermined threshold.

Abstract: A method includes converting a received time domain digital signal to a corresponding frequency domain digital signal, calculating phase angles of tones of at least one symbol of the frequency domain digital signal when a symbol timing offset exists, and calculating at least one differential phase offset (DPO). A DPO is the difference between two consecutive gaps, a gap being the difference between the phase angle of a tone of the symbol of the frequency domain digital signal when the timing offset of the symbol exists and a correct phase angle of the tone of the symbol of the frequency domain digital signal. The method estimates the symbol timing offset with at least one DPO.