Patent ID: 8194804
Filing Date: 2012-06-05
Classification: H04L

Abstract:
1. An automatic gain controller of a mobile station in an orthogonal frequency division multiplexing (OFDM) system, the automatic gain controller comprising: an amplifier for at least one of amplifying or attenuating a received forward frame signal according to a predetermined gain value; an analog to digital converter (ADC) for converting the at least one of amplified or attenuated signal to digital data; a fast Fourier transform (FFT) unit for fast Fourier transforming the digital data to frequency domain data; a synchronizer for providing preamble section and data symbol section information of the received forward frame signal; a channel estimator, identifying a preamble section and a data symbol section based on the information provided from the synchronizer, for measuring and outputting a power value of a preamble during the preamble section, and measuring and outputting an average power value of a pilot signal in a data symbol during the data symbol section; and a gain controller for receiving the power value of the preamble from the channel estimator during the preamble section, receiving the measured average power value of the pilot signal in the data symbol from the channel estimator during the data symbol section, and establishing gain of the amplifier for the preamble section according to a difference between the power value of the preamble and a threshold value, wherein, the gain controller compares the measured average power value of the pilot signal in the data symbol with the threshold value and reduces the gain of the amplifier by a predetermined value when the measured average power value of the pilot signal in the data symbol is equal to or higher than the threshold value, and wherein the gain controller increases the gain of the amplifier by the predetermined value when the measured average power value of the pilot signal in the data symbol is lower than the threshold value.