Abstract: A method and an apparatus for modulation recognition in communication system are provided. First, a plurality of constellation corresponding different modulation types are provided, wherein each constellation has a plurality of points. An input signal is de-mapped to find out a nearest point located nearest to a position of the input signal in each constellation. The distances from the nearest points to the position of the input signal are respectively counted to obtain a plurality of distance statistics values corresponding to different modulation types. The apparatus compares the distance statistics values for recognizing the modulation type of the input signal.

Abstract: A method and an apparatus for modulation recognition in communication system are provided. First, a plurality of constellation corresponding different modulation types are provided, wherein each constellation has a plurality of points. An input signal is de-mapped to find out a nearest point located nearest to a position of the input signal in each constellation. The distances from the nearest points to the position of the input signal are respectively counted to obtain a plurality of distance statistics values corresponding to different modulation types. The apparatus compares the distance statistics values for recognizing the modulation type of the input signal.

Abstract: A novel and simplified orthogonal frequency division multiplexing (OFDM) equalizer uses a coordinate rotation digital computer (CORDIC) to convert the estimated channel effects from rectangular coordinate to polar coordinate and to compensate the phase error with the same CORDIC circuit of synchronization. The OFDM equalizer comprises: a fast Fourier transformer (FFT); a channel estimation circuit; a coordinate translator, comprising a CORDIC circuit, to translate the channel estimation value into a polar coordinate value; a pilot extractor to extract pilot signals and to track minor phase offsets of the received signal to synchronize phase of said received signal; a phase rotator to compensate phase of the received signal according to the channel estimation value and the phase tracking estimation value, to generate the real value and imaginary value of the phase compensated signal; and an amplitude adjustment circuit. The coordinate translator and the phase rotator use the same CORDIC circuit.

Abstract: The CORDIC circuit of this invention comprises a buffer memory to record a plurality or a plurality of group of coordinate values; a phase selector to determine a rotation direction according to values recorded in said buffer memory; a rotation calculator to rotate an input coordinate for a predetermined angle and to calculate resulting coordinate value after such rotation; a rotation counter to count number of rotation being made to said input coordinate; and an angle accumulator to accumulate total rotation angle being made to said input coordinate according to value recorded by said rotation counter. The CORDIC circuit of this invention may further comprise a bit selector to shift bits of said input coordinate.

Abstract: A novel and simplified orthogonal frequency division multiplexing (OFDM) equalizer uses a coordinate rotation digital computer (CORDIC) to convert the estimated channel effects from rectangular coordinate to polar coordinate and to compensate the phase error with the same CORDIC circuit of synchronization.