Method and apparatus for modulation recognition in communication system
AssigneeNovatek Microelectronics Corp.
InventorYuan-Shin Chuang
Life of this patent
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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.
Claims3
A modulation recognition apparatus in a communication system, comprising:
- a first multiplication unit, for multiplying an absolute value of an input signal by the absolute value of the input signal;
- a de-mapping unit, coupled to the first multiplication unit, for respectively finding out a nearest point located nearest to a position of the input signal in a plurality of constellations according to an output of the first multiplication unit, wherein the constellations correspond to a plurality of modulation types;
- a statistics unit, coupled to the de-mapping unit, for respectively counting a signal distance between the nearest point and the position of the input signal in each of the constellations, so as to obtain a plurality of distance statistics values corresponding to the modulation types, wherein the statistics unit comprises a plurality of statistics devices, wherein each of the statistics devices counts the signal distance between the nearest point and the position of the input signal of a corresponding constellation, so as to obtain the distance statistics value of the corresponding constellation, wherein the statistics device comprises:
- a subtractor, for subtracting the output of the first multiplication unit from the nearest point;
- a value generating unit, for determining a point space between the nearest point and a neighbouring point according to an output of the subtractor, and outputting a reciprocal of the point space, wherein the output of the first multiplication unit is located between the nearest point and the neighbouring point;
- a second multiplication unit, for multiplying the reciprocal of the point space with the output of the subtractor;
- and
- an accumulator, for eliminating a positive/negative symbol of an output of the second multiplication unit, and accumulating the output of the second multiplication unit having the positive/negative symbol eliminated, so as to obtain one of the distance statistics values;
- and
- a decision unit, coupled to the statistics unit, for comparing the distance statistics values to recognize a modulation type of the input signal.
Dependencies are inferred from the claim text.