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lteFrequencyCorrect

Frequency offset correction

Syntax

  • out = lteFrequencyCorrect(cfg,in,foffset)
    example

Description

example

out = lteFrequencyCorrect(cfg,in,foffset) corrects for a specified frequency offset, foffset, in the time-domain waveform, in, by performing simple frequency modulation (FM). The parameters of the waveform, in, are specified in a settings structure, cfg, which must contain either the field NDLRB or NULRB to control whether a downlink or uplink signal is expected in in.

The input, foffset is the frequency offset, in hertz, present on the waveform, in. Therefore, the correction applied is FM modulation by –foffset.

Examples

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Perform frequency offset estimation and correction on an uplink signal, to which a frequency offset has been applied.

Generate uplink RMC A3-2.

[txWaveform,rgrid,cfg] = lteRMCULTool('A3-2',[1;0;0;1],'Fdd',2);

Apply an arbitrary frequency offset of 51.2 Hz.

t = (0:length(txWaveform)-1).'/cfg.SamplingRate;
txWaveform = txWaveform .* exp(1i*2*pi*51.2*t);

Estimate and display the frequency offset.

offset = lteFrequencyOffset(cfg,txWaveform);
disp(['Frequency offset: ' num2str(offset) ' Hz'])
Frequency offset: 51.2 Hz

Correct for the frequency offset.

rxWaveform = lteFrequencyCorrect(cfg,txWaveform,offset);

Finally, perform SC-FDMA demodulation.

rxGrid = lteSCFDMADemodulate(cfg,rxWaveform);

Input Arguments

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Waveform parameter settings, specified as a structure. cfg must contain either the field NDLRB, to specify a downlink configuration, or the field NULRB, to specify an uplink configuration.

Parameter FieldRequired or OptionalValuesDescription
NDLRBRequired

Positive scalar integer

Number of downlink resource blocks. (NRBDL)

Set this parameter field to specify a downlink configuration.

CyclicPrefixRequired

'Normal' (default), 'Extended'

Cyclic prefix length in the downlink

Only set this parameter field if you are specifying a downlink configuration.

NULRBRequired

Scalar integer from 6 to 110

Number of uplink resource blocks. (NRBUL)

Set this parameter field to specify an uplink configuration.

CyclicPrefixULRequired

'Normal' (default), 'Extended'

Uplink cyclic prefix length. Only set this parameter field if you are specifying an uplink configuration.

Data Types: struct

Time-domain waveform, specified as a numeric column vector.

Data Types: double | single
Complex Number Support: Yes

Waveform frequency offset, specified as a scalar value expressed in Hertz. The correction applied to in is FM modulation by –foffset.

Data Types: double

Output Arguments

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Offset-corrected waveform, returned as a numeric column vector.

Data Types: double | single
Complex Number Support: Yes

Introduced in R2014a

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