Create VHT format configuration object. Generate a time-domain waveform for an 802.11ac VHT packet.

vht = wlanVHTConfig;
txWaveform = wlanWaveformGenerator([1;0;0;1],vht);

Multiply the transmitted VHT signal by -0.1 + 0.5i and pass it through an AWGN channel with a 30 dB signal-to-noise ratio.

rxWaveform = awgn(txWaveform*(-0.1+0.5i),30);

Extract the L-LTF field indices and demodulate the L-LTF. Perform channel estimation without frequency smoothing.

idxLLTF = wlanFieldIndices(vht,'L-LTF');
demodSig = wlanLLTFDemodulate(rxWaveform(idxLLTF(1):idxLLTF(2),:),vht);

est = wlanLLTFChannelEstimate(demodSig,vht);

Plot the channel estimate.

scatterplot(est)
grid

The channel estimate matches the complex channel multiplier.

Generate a time domain waveform for an 802.11n HT packet, pass it through a TGn fading channel and perform L-LTF channel estimation. Trailing zeros are added to the waveform to allow for TGn channel delay.

Create the HT packet configuration and transmit waveform.

cfgHT = wlanHTConfig;
txWaveform = wlanWaveformGenerator([1;0;0;1],cfgHT);

Configure a TGn channel with 20 MHz bandwidth.

tgnChannel = wlanTGnChannel;
tgnChannel.SampleRate = 20e6;

Pass the waveform through the TGn channel, adding trailing zeros to allow for channel delay.

rxWaveform = tgnChannel([txWaveform; zeros(15,1)]);

Skip the first four samples to synchronize the received waveform for channel delay.

rxWaveform = rxWaveform(5:end,:);

Extract the L-LTF and perform channel estimation.

idnLLTF = wlanFieldIndices(cfgHT,'L-LTF');
sym = wlanLLTFDemodulate(rxWaveform(idnLLTF(1):idnLLTF(2),:),cfgHT);
est = wlanLLTFChannelEstimate(sym,cfgHT);

Create a VHT format configuration object. Using these objects, generate a time-domain waveform for an 802.11ac VHT packet.

vht = wlanVHTConfig('ChannelBandwidth','CBW80');
txWaveform = wlanWaveformGenerator([1;0;0;1],vht);

Multiply the transmitted VHT signal by -0.4 + 0.3i and pass it through an AWGN channel.

rxWaveform = awgn(txWaveform*(-0.4+0.3i),30);

Specify the channel bandwidth for demodulation and channel estimation. Extract the L-LTF field indices, demodulate the L-LTF, and perform channel estimation without frequency smoothing.

chanBW = 'CBW80';
idxLLTF = wlanFieldIndices(vht,'L-LTF');
demodSig = wlanLLTFDemodulate(rxWaveform(idxLLTF(1):idxLLTF(2),:),chanBW); 
est = wlanLLTFChannelEstimate(demodSig,chanBW);

Plot the channel estimate.

scatterplot(est)
grid

The channel estimate matches the complex channel multiplier.

Create a VHT format configuration object. Generate a time-domain waveform for an 802.11ac VHT packet.

vht = wlanVHTConfig;
txWaveform = wlanWaveformGenerator([1;0;0;1],vht);

Multiply the transmitted VHT signal by 0.2 - 0.6i and pass it through an AWGN channel having a 10 dB SNR.

rxWaveform = awgn(txWaveform*complex(0.2,-0.6),10);

Extract the L-LTF from the received waveform. Demodulate the L-LTF.

idxLLTF = wlanFieldIndices(vht, 'L-LTF');
lltfDemodSig = wlanLLTFDemodulate(rxWaveform(idxLLTF(1):idxLLTF(2),:),vht);

Use the demodulated L-LTF signal to generate the channel estimate.

est = wlanLLTFChannelEstimate(lltfDemodSig,vht);

Plot the channel estimate.

scatterplot(est)
grid

The channel estimate is noisy, which may lead to inaccurate data recovery.

Estimate the channel again with the filter span set to 11.

est = wlanLLTFChannelEstimate(lltfDemodSig,vht,11);
scatterplot(est)
grid

The filtering provides a better channel estimate.

Create a VHT format configuration object. Generate L-LTF and VHT-SIG-A fields.

vht = wlanVHTConfig;
txLLTF = wlanLLTF(vht);
txSig = wlanVHTSIGA(vht);

Create a TGac channel for an 80 MHz bandwidth and a Model-A delay profile. Pass the transmitted L-LTF and VHT-SIG-A signals through the channel.

tgacChan = wlanTGacChannel('SampleRate',80e6,'ChannelBandwidth','CBW80', ...
    'DelayProfile','Model-A');

rxLLTFNoNoise = tgacChan(txLLTF);
rxSigNoNoise = tgacChan(txSig);

Create an AWGN noise channel with an SNR = 15 dB. Add the AWGN noise to L-LTF and VHT-SIG-A signals.

chNoise = comm.AWGNChannel('NoiseMethod','Signal to noise ratio (SNR)', ...
    'SNR',15);

rxLLTF = chNoise(rxLLTFNoNoise);
rxSig = chNoise(rxSigNoNoise);

Create an AWGN channel having a noise variance corresponding to a 9 dB noise figure receiver. Pass the faded signals through the AWGN channel.

nVar = 10^((-228.6 + 10*log10(290) + 10*log10(80e6) + 9)/10);
awgnChan = comm.AWGNChannel('NoiseMethod','Variance','Variance',nVar);

rxLLTF = awgnChan(rxLLTF);
rxSig = awgnChan(rxSig);

Demodulate the received L-LTF.

demodLLTF = wlanLLTFDemodulate(rxLLTF,vht);

Estimate the channel using the demodulated L-LTF.

chEst = wlanLLTFChannelEstimate(demodLLTF,vht);

Recover the VHT-SIG-A signal and verify that there was no CRC failure.

[recBits,crcFail] = wlanVHTSIGARecover(rxSig,chEst,nVar,'CBW80');
crcFail

crcFail = logical
   0