Hi Jaya,
In order to achieve robust timing and frequency synchronization for OFDM, you can follow the below steps:
Generate OFDM Signal:
Create an OFDM signal with known parameters for testing.
N = 64; % Number of subcarriers
cpLen = 16; % Cyclic prefix length
data = randi([0 1], N, 1); % Random data
modData = qammod(data, 16); % 16-QAM modulation
ifftData = ifft(modData); % IFFT
ofdmSignal = [ifftData(end-cpLen+1:end); ifftData]; % Add cyclic prefix
Add Noise and Frequency Offset:
Simulate a channel with noise and frequency offset.
freqOffset = 0.01; % Frequency offset
t = (0:length(ofdmSignal)-1)';
receivedSignal = ofdmSignal .* exp(1j*2*pi*freqOffset*t) + 0.1*randn(size(ofdmSignal));
Coarse Timing Synchronization:
Use correlation with a known preamble to estimate the start of the OFDM symbol.
preamble = ifft(ones(N, 1)); % Example preamble
corr = abs(conv(receivedSignal, flipud(conj(preamble))));
[~, timingOffset] = max(corr); % Estimate timing offset
Frequency Offset Estimation:
Estimate frequency offset using the phase difference between consecutive symbols.
phaseDiff = angle(receivedSignal(cpLen+1:N+cpLen) .* conj(receivedSignal(1:N)));
estimatedFreqOffset = mean(phaseDiff) / (2*pi*N);
Correct Frequency Offset:
Compensate for the frequency offset in the received signal.
correctedSignal = receivedSignal .* exp(-1j*2*pi*estimatedFreqOffset*t);
Refer to the documentation of "qammod" function for QAM modulation details: https://www.mathworks.com/help/comm/ref/qammod.html
Refer to the documentation of "ifft" function for inverse FFT details: https://www.mathworks.com/help/matlab/ref/ifft.html
Hope this helps!
