Main Content

getSIGBLength

Return information relevant to HE-SIG-B field length

Description

example

info = getSIGBLength(cfg) returns a structure, info, which contains information relevant to the HE-SIG-B field length of the high-efficiency (HE) recovery configuration object cfg. The input cfg contains the parameters recovered from decoding the signaling fields of an HE-format waveform.

Examples

collapse all

Create a WLAN HE-MU-format configuration object, specifying the allocation index.

cfgHEMU = wlanHEMUConfig(0);

Generate a WLAN waveform for the specified configuration and return the PPDU field indices.

waveform = wlanWaveformGenerator(1,cfgHEMU);
ind = wlanFieldIndices(cfgHEMU);

Decode the L-SIG field and obtain the OFDM information. This information is required to obtain the L-SIG length, which is used in the recovery configuration object.

lsig = waveform(ind.LSIG(1):ind.LSIG(2),:);
lsigDemod = wlanHEDemodulate(lsig,'L-SIG',cfgHEMU.ChannelBandwidth);
preHEInfo = wlanHEOFDMInfo('L-SIG',cfgHEMU.ChannelBandwidth);

Recover the L-SIG information bits and related information, making sure that the bits pass the parity check. For this example, we assume a noiseless channel. For more realistic results you can pass the waveform through an 802.11ax™ channel model by using the wlanTGaxChannel System object™ and work with the received waveform.

csi = ones(52,1);
[lsigBits,failCheck,lsigInfo] = wlanLSIGBitRecover(lsigDemod(preHEInfo.DataIndices,:,:),0,csi);

Decode the HE-SIG-A field and recover the HE-SIG-A information bits, ensuring that the bits pass the cyclic redundancy check (CRC).

siga = waveform(ind.HESIGA(1):ind.HESIGA(2),:);
sigaDemod = wlanHEDemodulate(siga,'HE-SIG-A',cfgHEMU.ChannelBandwidth);
preHEInfo = wlanHEOFDMInfo('HE-SIG-A',cfgHEMU.ChannelBandwidth);
[bits,failCRC] = wlanHESIGABitRecover(sigaDemod(preHEInfo.DataIndices,:,:),0,csi);

Create a WLAN recovery configuration object, specifying an HE-MU-format packet and the length of the L-SIG field.

cfg = wlanHERecoveryConfig('PacketFormat','HE-MU','LSIGLength',lsigInfo.Length);

Update the recovery configuration object with the recovered HE-SIG-A bits.

cfgUpdated = interpretHESIGABits(cfg,bits);

Return and display the HE-SIG-B information.

info = getSIGBLength(cfgUpdated);
disp(info);
    NumSIGBCommonFieldSamples: 80
               NumSIGBSymbols: 10

Input Arguments

collapse all

HE recovery configuration object, specified as a wlanHERecoveryConfig object.

Output Arguments

collapse all

Information relevant to the HE-SIG-B field length, returned as a structure containing these fields.

Number of samples in HE-SIG-B common field, returned as a nonnegative integer.

Data Types: double

Total number of symbols in HE-SIG-B field, returned as a nonnegative integer.

Data Types: double

Data Types: struct

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Introduced in R2019a