Azzera filtri
Azzera filtri

I am getting some errors of a script that I try to run

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When I run below script
% Parameters
M = 16; % Modulation order
k = log2(M); % Bits per symbol
numBits = k * 2.5e5; % Total bits to process
sps = 4; % Samples per symbol (oversampling factor)
filtlen = 10; % Filter length in symbols
rolloff = 0.25; % Filter rolloff factor
% Generate random binary data
dataIn = randi([0 1], numBits, 1);
% Apply convolutional encoding
constrlen = [5 4]; % Code constraint length
genpoly = [23 35 0; 0 5 13]; % Generator polynomials
tPoly = poly2trellis(constrlen, genpoly);
dataEnc = convenc(dataIn, tPoly);
% Modulate using 16-QAM
dataSymbolsIn = bit2int(dataEnc, k);
dataMod = qammod(dataSymbolsIn, M);
% Apply raised cosine filtering
rrcFilter = rcosdesign(rolloff, filtlen, sps);
txSignal = upfirdn(dataMod, rrcFilter, sps, 1);
% Add AWGN (simulate noisy channel)
SNR_dB = 10; % Signal-to-noise ratio in dB
rxSignal = awgn(txSignal, SNR_dB, 'measured');
% Demodulate 16-QAM
dataSymbolsOut = qamdemod(rxSignal, M, 'OutputType', 'bit');
% Viterbi decoding
decodedData = vitdec(dataSymbolsOut, tPoly, 100, 'trunc', 'hard');
% Calculate bit error rate
bitErrors = biterr(dataIn, decodedData);
bitErrorRate = bitErrors / numBits;
fprintf('Bit Error Rate: %.4f\n', bitErrorRate);
I am getting below errors,
Error using vitdec (line 271)
Length of the input code vector must be a multiple of the number of bits in an
input symbol.
Error in test3 (line 34)
decodedData = vitdec(dataSymbolsOut, tPoly, 100, 'trunc', 'hard');
can someone help me to correct them

Risposte (1)

Alberto Alvarez Polegre
Alberto Alvarez Polegre il 17 Apr 2024
You forgot to include the filter at the receiver. Try this:
% Parameters
M = 16; % Modulation order
k = log2(M); % Bits per symbol
numBits = k * 2.5e5; % Total bits to process
sps = 4; % Samples per symbol (oversampling factor)
filtlen = 10; % Filter length in symbols
rolloff = 0.25; % Filter rolloff factor
% Generate random binary data
dataIn = randi([0 1], numBits, 1);
% Apply convolutional encoding
constrlen = [5 4]; % Code constraint length
genpoly = [23 35 0; 0 5 13]; % Generator polynomials
tPoly = poly2trellis(constrlen, genpoly);
dataEnc = convenc(dataIn, tPoly);
% Modulate using 16-QAM
dataMod = qammod(dataEnc,M,InputType='bit');
% Transmit filter
rrcFilter = rcosdesign(rolloff,filtlen,sps);
txSignal = upfirdn(dataMod,rrcFilter,sps);
% Add AWGN (simulate noisy channel)
SNR_dB = 10; % Signal-to-noise ratio in dB
rxSignal = awgn(txSignal, SNR_dB, 'measured');
% Receive filter
rxSignalFilt = upfirdn(rxSignal,rrcFilter,1,sps); % Apply receive filter
rxSignalFilt = rxSignalFilt(filtlen+1:end-filtlen); % Account for filter delay
% Demodulate 16-QAM
dataSymbolsOut = qamdemod(rxSignalFilt, M, 'OutputType', 'bit');
% Viterbi decoding
decodedData = vitdec(dataSymbolsOut, tPoly, 100, 'trunc', 'hard');
% Calculate bit error rate
bitErrors = biterr(dataIn, decodedData);
bitErrorRate = bitErrors / numBits;
fprintf('Bit Error Rate: %.4f\n', bitErrorRate);
You might want to take a look at the Wireless Communications Onramp course.

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