Patent ID: 7486736

Claim:
An apparatus for direct measurement of the channel state of an OFDM (Orthogonal Frequency Division Multiplexing) receiver comprising: a de-mapping and pilot insertion unit which receives complex OFDM signals, performs de-mapping processing corresponding to data carriers, TPSC (Transmission Parameter Signaling Carriers) and one of CPC (Continual Pilot Carrier) and SPC (Scattered Pilot Carrier) of the complex OFDM signals, and outputs the de-mapped signals; a subtraction unit which subtracts the complex OFDM signals from the de-mapped signals and outputs the subtracted values; a squared Euclidean distance calculation unit which calculates a squared value of a signal for I (In-phase) and a squared value of a signal for Q (Quadrature) of output signals of the subtraction unit, and outputs a first error which is a sum of the squared values; a non-recursive carrier filtering unit which delays the first error one carrier at a time, multiplies filtering coefficients by a present carrier value of the first error and multiple delayed carrier values, and outputs a second error which is a sum of the multiplied values; a data carrier extraction unit which extracts and outputs an error corresponding to the data carrier from the second error; a recursive symbol filtering unit which outputs a third error which averages the output error of the data carrier extraction unit and a previous symbol; and a quantization unit which receives the third error, inverts the third error with non-linear transfer function relation, and outputs a CSI (Channel State Information) signal including quantized multiple bits.