## BER curve from this code

### abdullah qasim (view profile)

on 10 Jan 2019
my friends
I want to do BER curve of this code but here gives me one value and be raised to the positive please help me solve this problem for the FBMC & OFDM,
this code from Mathwork.
s = rng(211); % Set RNG state for repeatability
%%
numFFT = 1024; % Number of FFT points
numGuards =212 ; % Guard bands on both sides
K = 4; % Overlapping symbols, one of 2, 3, or 4
numSymbols = 100; % Simulation length in symbols
bitsPerSubCarrier = 2; % 2: 4QAM, 4: 16QAM, 6: 64QAM, 8: 256QAM
snrdB = 12; % SNR in dB
%%
% Prototype filter
switch K
case 2
HkOneSided = sqrt(2)/2;
case 3
HkOneSided = [0.911438 0.411438];
case 4
end
% Build symmetric filter
Hk = [fliplr(HkOneSided) 1 HkOneSided];
% QAM symbol mapper
qamMapper = comm.RectangularQAMModulator(...
'ModulationOrder', 2^bitsPerSubCarrier, ...
'BitInput', true, ...
'NormalizationMethod', 'Average power');
% Transmit-end processing
% Initialize arrays
L = numFFT-2*numGuards; % Number of complex symbols per OFDM symbol
KF = K*numFFT;
KL = K*L;
dataSubCar = zeros(L, 1);
dataSubCarUp = zeros(KL, 1);
sumFBMCSpec = zeros(KF*2, 1);
sumOFDMSpec = zeros(numFFT*2, 1);
numBits = bitsPerSubCarrier*L/2; % account for oversampling by 2
inpData = zeros(numBits, numSymbols);
rxBits = zeros(numBits, numSymbols);
txSigAll = complex(zeros(KF, numSymbols));
symBuf = complex(zeros(2*KF, 1));
%%
% Loop over symbols
for symIdx = 1:numSymbols
% Generate mapped symbol data
inpData(:, symIdx) = randi([0 1], numBits, 1);
modData = qamMapper(inpData(:, symIdx));
% OQAM Modulator: alternate real and imaginary parts
if rem(symIdx,2)==1 % Odd symbols
dataSubCar(1:2:L) = real(modData);
dataSubCar(2:2:L) = 1i*imag(modData);
else % Even symbols
dataSubCar(1:2:L) = 1i*imag(modData);
dataSubCar(2:2:L) = real(modData);
end
% Upsample by K, pad with guards, and filter with the prototype filter
dataSubCarUp(1:K:end) = dataSubCar;
% Remove 1/2 filter length delay
X = [X1(K:end); zeros(K-1,1)];
% Compute IFFT of length KF for the transmitted symbol
txSymb = fftshift(ifft(X));
% Transmitted signal is a sum of the delayed real, imag symbols
symBuf = [symBuf(numFFT/2+1:end); complex(zeros(numFFT/2,1))];
symBuf(KF+(1:KF)) = symBuf(KF+(1:KF)) + txSymb;
% Compute power spectral density (PSD)
currSym = complex(symBuf(1:KF));
[specFBMC, fFBMC] = periodogram(currSym, hann(KF, 'periodic'), KF*2, 1);
sumFBMCSpec = sumFBMCSpec + specFBMC;
% Store transmitted signals for all symbols
txSigAll(:,symIdx) = currSym;
end
%% Plot power spectral density
sumFBMCSpec = sumFBMCSpec/mean(sumFBMCSpec(1+K+2*numGuards*K:end-2*numGuards*K-K));
plot(fFBMC-0.5,10*log10(sumFBMCSpec));
grid on
axis([-0.5 0.5 -220 10]);
xlabel('Normalized frequency');
ylabel('PSD (dBW/Hz)')
title(['FBMC, K = ' num2str(K) ' overlapped symbols'])
set(gcf, 'Position', figposition([15 50 30 30]));
%%
for symIdx = 1:numSymbols
inpData2 = randi([0 1], bitsPerSubCarrier*L, 1);
modData = qamMapper(inpData2);
symOFDM = [zeros(numGuards,1); modData; zeros(numGuards,1)];
ifftOut = sqrt(numFFT).*ifft(ifftshift(symOFDM));
[specOFDM,fOFDM] = periodogram(ifftOut, rectwin(length(ifftOut)), ...
numFFT*2, 1, 'centered');
sumOFDMSpec = sumOFDMSpec + specOFDM;
end
% Plot power spectral density (PSD) over all subcarriers
sumOFDMSpec = sumOFDMSpec/mean(sumOFDMSpec(1+2*numGuards:end-2*numGuards));
figure;
plot(fOFDM,10*log10(sumOFDMSpec));
grid on
axis([-0.5 0.5 -180 10]);
xlabel('Normalized frequency');
ylabel('PSD (dBW/Hz)')
title(['OFDM, numFFT = ' num2str(numFFT)])
set(gcf, 'Position', figposition([46 50 30 30]));
%%
% QAM demodulator
qamDemod = comm.RectangularQAMDemodulator(...
'ModulationOrder', 2^bitsPerSubCarrier, ...
'BitOutput', true, ...
'NormalizationMethod', 'Average power');
BER = comm.ErrorRate;
% Process symbol-wise
for symIdx = 1:numSymbols
rxSig = txSigAll(:, symIdx);
rxNsig = awgn(rxSig, snrdB, 'measured');
% Perform FFT
rxf = fft(fftshift(rxNsig));
% Matched filtering with prototype filter
rxfmf = filter(Hk, 1, rxf);
% Remove K-1 delay elements
rxfmf = [rxfmf(K:end); zeros(K-1,1)];
% Remove guards
rxfmfg = rxfmf(numGuards*K+1:end-numGuards*K);
% OQAM post-processing
% Downsample by 2K, extract real and imaginary parts
if rem(symIdx, 2)
% Imaginary part is K samples after real one
r1 = real(rxfmfg(1:2*K:end));
r2 = imag(rxfmfg(K+1:2*K:end));
rcomb = complex(r1, r2);
else
% Real part is K samples after imaginary one
r1 = imag(rxfmfg(1:2*K:end));
r2 = real(rxfmfg(K+1:2*K:end));
rcomb = complex(r2, r1);
end
% Normalize by the upsampling factor
rcomb = (1/K)*rcomb;
% Demapper: Perform hard decision
rxBits(:, symIdx) = qamDemod(rcomb);
end
% Measure BER with appropriate delay
ber = BER(inpData(:), rxBits(:));
% Display Bit error
disp(['FBMC Reception for K = ' num2str(K) ', BER = ' num2str(ber(1)) ...
' at SNR = ' num2str(snrdB) ' dB'])
% Restore RNG state
rng(s);