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US 7,257,165 B2Granted
Method and apparatus for preamble detection and time synchronization estimation in OFDM communication systems
OwnerSteven H. Gardnerinventor
Life of this patent
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Abstract
A novel method and apparatus for preamble detection and time synchronization estimation in OFDM communication systems is described. The present invention can be easily implemented to provide preamble detection and highly accurate time synchronization estimations. The inventive method and apparatus utilizes phase and magnitude information obtained from a received signal to detect a preamble and to calculate a time synchronization estimation for the received signal.
Claims31
A receiver circuit, adapted to receive an input signal from a transmitter in a communication system, comprising:
- (a) an input node capable of receiving an analog input signal and a plurality of reference samples H(n);
- (b) an FFT generator, adapted to receive the analog input signal, wherein the FFT generator generates a plurality of complex frequency domain samples R(n);
- (c) a first complex conjugator, adapted to receive the plurality of reference samples H(n), wherein the first complex conjugator generates a plurality of reference sample complex conjugates H*(n);
- (d) a first multiplier, adapted to receive the plurality of complex frequency domain samples R(n) and the plurality of reference sample complex conjugates H*(n), wherein the first multiplier multiplies the plurality of complex frequency domain samples R(n) by the plurality of reference sample complex conjugates H*(n) and generates a plurality of resultant vectors C(n);
- (e) a difference vector multiplier, adapted to receive the plurality of resultant vectors C(n), wherein the difference vector multiplier generates a plurality of difference vectors D(n);
- (f) an accumulator, adapted to receive the plurality of difference vectors D(n), wherein the accumulator generates a vector sum S and outputs a magnitude and a phase based on the vector sum S;
- (g) a timing error estimator, adapted to receive the phase, wherein the timing error estimator generates a timing error k based on the phase;
- and
- (h) a comparator, adapted to receive the magnitude, wherein the comparator detects a preamble based on the magnitude.
6 more elements
A method of preamble detection and time synchronization in an OFDM communication system, wherein the communication system includes a transmitter capable of communicating with a receiver, and wherein the communication system utilizes an OFDM modulation scheme, and wherein the communication system utilizes a plurality of system tones to transmit data, the method comprising:
- (a) performing a Fast Fourier Transform (FFT) on an input signal to produce a plurality of complex tone samples, wherein each complex tone sample corresponds to a system tone;
- (b) performing complex conjugation on a plurality of reference samples to produce a plurality of complex conjugate reference samples;
- (c) multiplying the plurality of complex tone samples by the plurality of complex conjugate reference samples to produce a plurality of resultant vectors;
- (d) generating a plurality of difference vectors based on the plurality of resultant vectors;
- (e) summing the plurality of difference vectors to produce a vector sum;
- and
- (f) utilizing a magnitude and a phase of the vector sum to detect a preamble and estimate time synchronization.
4 more elements
An apparatus, adapted to receive an input signal from a transmitter in a communication system, comprising:
- (a) an input means for receiving an analog input signal and a plurality of reference samples H(n);
- (b) an FFT generating means, operatively coupled to and responsive to the input means, for generating a plurality of complex frequency domain samples R(n);
- (c) a first complex conjugation means for receiving a plurality of reference samples H(n) and generating a plurality of reference sample complex conjugates H*(n);
- (d) a first multiplier means, operatively coupled to the FFT generating means and the first complex conjugation means, for generating a plurality of resultant vectors C(n) by multiplying the plurality of complex frequency domain samples R(n) by the plurality of reference sample complex conjugates H*(n);
- (e) a difference vector multiplier means, operatively coupled to the first multiplier means, for generating a plurality of difference vectors D(n);
- (f) an accumulator means, operatively coupled to the difference vector multiplier means, for generating a vector sum S and outputting a magnitude and a phase based on the vector sum S;
- (g) a timing error estimator means, operatively coupled to the accumulator means, for generating a timing error k based on the phase;
- and
- (h) a comparator means, operatively coupled to the accumulator means, for detecting a preamble based on the magnitude.
6 more elements
An apparatus, comprising:
- (a) a transmitter means for transmitting a transmitted signal;
- and
- (b) a receiver means for receiving the transmitted signal, comprising:
- (1) an input means for receiving an analog input signal and a plurality of reference samples H(n);
- (2) an FFT generating means, operatively coupled to and responsive to the input means, for generating a plurality of complex frequency domain samples R(n);
- (3) a first complex conjugation means, operatively coupled to and responsive to the input means, for generating a plurality of reference sample complex conjugates H*(n);
- (4) a first multiplier means, operatively coupled to the FFT generating means and the first complex conjugation means, for generating a plurality of resultant vectors C(n) by multiplying the plurality of complex frequency domain samples R(n) by the plurality of reference sample complex conjugates H*(n);
- (5) a difference vector multiplier means, operatively coupled to the first multiplier means, for generating a plurality of difference vectors D(n);
- (6) an accumulator means, operatively coupled to the difference vector multiplier means, for generating a vector sum S and outputting a magnitude and a phase based on the vector sum S;
- (7) a timing error estimator means, operatively coupled to the accumulator means, for generating a timing error k based on the phase;
- and
- (8) a comparator means, operatively coupled to the accumulator means, for detecting a preamble based on the magnitude.
9 more elements
An apparatus, comprising:
- (a) means for performing a Fast Fourier Transform (FFT) on an input signal to produce a plurality of complex tone samples, wherein each complex tone sample corresponds to a system tone;
- (b) means for performing complex conjugation on a plurality of reference samples to produce a plurality of complex conjugate reference samples;
- (c) means, operatively coupled to the performing an FFT means and performing complex conjugation means, for multiplying the plurality of complex tone samples by the plurality of complex conjugate reference samples to produce a plurality of resultant vectors;
- (d) means, operatively coupled to the multiplying means, for generating a plurality of difference vectors based on the plurality of resultant vectors
- (e) means, operatively coupled to the generating means, for summing the plurality of difference vectors to produce a vector sum;
- and
- (f) means, operatively coupled to the summing means, for utilizing a magnitude and a phase of the vector sum to detect a preamble and estimate time synchronization.
4 more elements
A computer readable medium having imparted thereon a plurality of sets of instructions including:
- (a) a first set of instructions for performing a Fast Fourier Transform (FET) on an input signal to produce a plurality of complex tone samples, wherein each complex tone sample corresponds to a system tone;
- (b) a second set of instructions for performing complex conjugation on a plurality of reference samples to produce a plurality of complex conjugate reference samples;
- (c) a third set of instructions for multiplying the plurality of complex tone samples by the plurality of complex conjugate reference samples to produce a plurality of resultant vectors;
- (d) a fourth set of instructions for generating a plurality of difference vectors based on the plurality of resultant vectors;
- (e) a fifth set of instructions for summing the plurality of difference vectors to produce a vector sum;
- and
- (f) a sixth set of instructions for utilizing a magnitude and a phase of the vector sum to detect a preamble and estimate time synchronization.
4 more elements
Dependencies are inferred from the claim text.