Main Content

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

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 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 frames of random input samples.

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


Convert the framed input data to a stream of samples and input the stream to the LTE Symbol Modulator Simulink block.

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

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

Run the Simulink model.

modelname = 'ltehdlSymbolModulatorModel';

Export the stream of modulated samples from Simulink to the MATLAB workspace.

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

Modulate data bits with lteSymbolModulate function and use its output as a reference data.

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

Compare the output of the Simulink model against the output of 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 

See Also