Here is the outline of the procedure along with documentation links to generate the bitstream using a protocol and then passing this to Simulink for further analysis:
- Generate Protocol frame: You need to create a function that generates a protocol frame with a header and a payload. You may use any other protocol too.
function bitStream = generateProtocolFrame(frameNum, frameSize)
headerSize = 16; % Number of bits in the header
payloadSize = frameSize - headerSize; % Number of bits in the payload
% Header: Frame number (16 bits)
header = de2bi(frameNum, headerSize, 'left-msb')';
% Payload: Random data bits
payload = randi([0 1], payloadSize, 1);
% Combine header and payload
bitStream = [header; payload];
end
2. Modulation: For DBPSK modulation, use ‘dpskmod’ function in MATLAB. Documentation link: https://www.mathworks.com/help/comm/ref/comm.dpskmodulator-system-object.html
txSignal = dpskmod(txBits, 2);
3. Tx filtering (RRC Filter): Design and apply an RRC filter using ‘rcosdeign’. Documentation link: https://www.mathworks.com/help/signal/ref/rcosdesign.html
rolloff = 0.25; % Roll-off factor
span = 10; % Filter span in symbols
sps = 4; % Samples per symbol
rrcFilter = rcosdesign(rolloff, span, sps);
txSignalFiltered = filter(rrcFilter, 1, txSignalUpsampled);
4. Upconvert from Baseband (BB) to RF: Upconvert the signal to RF using a carrier frequency ‘fc’.
fc = 1e3; % Carrier frequency
fs = 10e3; % Sampling frequency
t = (0:length(txSignalFiltered)-1)'/fs;
txSignalRF = real(txSignalFiltered .* exp(1i*2*pi*fc*t));
5. Send over an AWGN Channel: Pass the signal through an AWGN channel using ‘awgn’. Documentation link: https://www.mathworks.com/help/comm/ref/awgn.html
SNR = 10; % Signal-to-Noise Ratio in dB
rxSignalRF = awgn(txSignalRF, SNR, 'measured');
6. Downconvert from RF to BB: Downconvert the received RF signal back to baseband.
rxSignalBB = rxSignalRF .* exp(-1i*2*pi*fc*t);
7. Automatic Gain Control(AGC): Normalize the received signal.
rxSignalAGC = rxSignalBB / max(abs(rxSignalBB));
8. RX Filtering (RRC filter): Apply the same RRC filter to the received signal.
rxSignalFiltered = filter(rrcFilter, 1, rxSignalAGC);
9. Demodulation: Demodulate the signal using ‘dpskdemod’. Documentation link: https://ww.mathworks.com/help/comm/ref/dpskdemod.html
rxBits = dpskdemod(rxSignalDownsampled, 2);
10. Calculate the PER: Compare the transmitted and received bits and calculate the PER.
numErrors = sum(txBits ~= rxBits);
PER = numErrors / (numFrames * frameSize);
disp(['Packet Error Rate (PER): ', num2str(PER)]);
11. Pass data to Simulink: Pass the bitstream data to Simulink for further processing. Documentation link: https://www.mathworks.com/help/simulink/slref/sim.html
bitstreamData = bitstreamData';
simOut = sim('bitstream_processing', 'SimulationMode', 'normal', ...
'SaveOutput', 'on', 'OutputSaveName', 'yout', ...
'SrcWorkspace', 'current');
Hope it helps!
Best,
Zinea
