PSK Modulation performance in rayleigh channel

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Yashar
Yashar 2012-11-3
评论： ABDUL 2020-10-2
Hi dear friends:
I intend to simulate the performance of PSK modulation in rayleigh channel. First I used the example of Matlab for DPSK which is:
% Create Rayleigh fading channel object.
chan = rayleighchan(1/10000,100);
% Generate data and apply fading channel.
M = 2; % DBPSK modulation order
hMod = modem.dpskmod('M', M); % Create a DPSK modulator
hDemod = modem.dpskdemod(hMod); % Create a DPSK demodulator
% using the modulator
tx = randi([0 M-1],50000,1); % Generate a random bit stream
dpskSig = modulate(hMod, tx); % DPSK modulate the signal
fadedSig = filter(chan,dpskSig); % Apply the channel effects
% Compute error rate for different values of SNR.
SNR = 0:2:20; % Range of SNR values, in dB.
numSNR = length(SNR);
BER = zeros(1, numSNR);
for n = 1:numSNR
rxSig = awgn(fadedSig,SNR(n)); % Add Gaussian noise
rx = demodulate(hDemod, rxSig); % Demodulate
reset(hDemod);
% Compute error rate.
[nErrors, BER(n)] = biterr(tx,rx);
end
% Compute theoretical performance results, for comparison.
BERtheory = berfading(SNR,'dpsk',M,1);
% Plot BER results.
semilogy(SNR,BERtheory,'b-',SNR,BER,'r*');
legend('Theoretical BER','Empirical BER');
xlabel('SNR (dB)'); ylabel('BER');
title('Binary DPSK over Rayleigh Fading Channel');
the output for this code is sensible and it fits the theoretical curve.
But when I edit the code to do the simulations for psk modulation like bellow:
hMod = modem.pskmod('M', M);
hDemod = modem.pskdemod(hMod);
This time I get an approximately flat line as the BER curve. I don't know what's wrong with it?! It will be very appreciated if you help me with this tricky problem.

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回答（1 个）

Deepak Rathore
Deepak Rathore 2013-4-21
Dear This is due to not using the channel estimation or equalizer. DPSK not require but bpsk, qpsk and qam require the channel compensation at the receiver.
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Yashar
Yashar 2020-7-19
Thank you very much for your answer to my question.
ABDUL
ABDUL 2020-10-2
which is the best channel estimation or equalizer that can be used for m-ary psk for implementing the BER of the M-ary psk systems
Regards
Abdul Azeez

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