LTE Symbol Modulation of Data Bits

This example shows how to use the LTE Symbol Modulator block to modulate data bits to complex data symbols. You can generate HDL code from this block.

Set up Input Parameters

Choose a data length for each modulation type. The data length must be an integer multiple of number of bits per symbol.

rng(0);
framesize = 240;

% Map modulation names to values
% 0 - BPSK
% 1 - QPSK
% 2 - 16-QAM
% 3 - 64-QAM
% 4 - 256-QAM
% others - QPSK

% For LTE Symbol Modulator Simulink(R) block
modSelVal = [0;1;2;3;4];

% For |lteSymbolModulate| function
modSelStr = {'BPSK','QPSK','16QAM','64QAM','256QAM'};

outWordLength = 16;
numframes = length(modSelVal);
dataBits  = cell(1,numframes);
modSelTmp = cell(1,numframes);
lteFcnOutput = cell(1,numframes);

Generate Input Data

Generate frames of random input samples. Convert the framed input data to a stream of samples and provide these samples as input to the Simulink block.

for ii = 1:numframes
    dataBits{ii} = logical(randi([0 1],framesize,1));
    modSelTmp{ii} = fi(modSelVal(ii)*ones(framesize,1),0,3,0);

end

idlecyclesbetweensamples = 0;
idlecyclesbetweenframes  = 0;
[sampleIn, ctrl] = whdlFramesToSamples(dataBits,idlecyclesbetweensamples,...
    idlecyclesbetweenframes);
[modSel, ~] = whdlFramesToSamples(modSelTmp,idlecyclesbetweensamples,...
    idlecyclesbetweenframes);
load = logical(ctrl(:,1)');
validIn = logical(ctrl(:,3)');

sampletime = 1;
samplesizeIn = 1;
simTime = size(ctrl,1);

Run Model

Running the Simulink model exports the stream of modulated samples from Simulink to the MATLAB® workspace.

modelname = 'ltehdlSymbolModulatorModel';
open_system(modelname);
sim(modelname);

sampleOut = squeeze(sampleOut).';
lteHDLOutput = sampleOut(squeeze(validOut));

Generate Reference Data

Modulate data bits with the <docid:lte_ref#bt16g53 lteSymbolModulate function and use the output of this function as a reference data.

for ii = 1:numframes
    lteFcnOutput{ii} = lteSymbolModulate(dataBits{ii},modSelStr{ii}).';
end

Compare Model Output with Function Output

Compare the output of the Simulink model against the output of the lteSymbolModulate function.

fprintf('\nLTE Symbol Modulator\n');
lteFcnOutput = fi(cell2mat(lteFcnOutput),1,outWordLength,outWordLength-2);
difference = sum(abs(lteHDLOutput-lteFcnOutput(1:length(lteHDLOutput))));
fprintf('\nTotal number of samples differed between Simulink block output and Reference data output: %d \n',difference);

LTE Symbol Modulator

Total number of samples differed between Simulink block output and Reference data output: 0