wlanHESIGABitRecover
Recover information bits in HE-SIG-A field
Syntax
Description
[
recovers bits
,failCRC
] = wlanHESIGABitRecover(siga
,noiseVarEst
)bits
, the information bits contained in
siga
, the HE-SIG-A field of an IEEE®
802.11™ high-efficiency transmission subject to channel noise with estimated variance
noiseVarEst
. The function also returns failCRC
,
the result of the cyclic redundancy check (CRC) on bits
.
For more information on 802.11ax™ signal recovery, see Recovery Procedure for an 802.11ax Packet.
Examples
Recover Information Bits in HE-SIG-A Field
Create a WLAN HE SU configuration object with default settings and use it to generate a waveform.
cfgHE = wlanHESUConfig; cbw = cfgHE.ChannelBandwidth; waveform = wlanWaveformGenerator(1,cfgHE);
Get the WLAN field indices. Use them to isolate the HE-SIG-A field.
ind = wlanFieldIndices(cfgHE); rxSIGA = waveform(ind.HESIGA(1):ind.HESIGA(2),:);
Perform OFDM demodulation to extract the HE-SIG-A field.
sigaDemod = wlanHEDemodulate(rxSIGA,'HE-SIG-A',cbw);
Return the pre-HE OFDM information and use it to extract the demodulated HE-SIG-A data symbols.
preHEInfo = wlanHEOFDMInfo('HE-SIG-A',cbw);
siga = sigaDemod(preHEInfo.DataIndices,:);
Recover the HE-SIG-A information bits and other information, assuming no channel noise. Display the parity check result.
noiseVarEst = 0; [bits,failCRC] = wlanHESIGABitRecover(siga,noiseVarEst); disp(failCRC);
0
Recover HE-SIG-A Information Bits with Channel State Information
Recover the information bits in the HE-SIG-A field of a WLAN HE multiuser (HE-MU) waveform with specified channel state information.
Create a WLAN HE-MU-format configuration object with default settings and use it to generate an HE-MU waveform.
cfgHE = wlanHEMUConfig(0); cbw = cfgHE.ChannelBandwidth; waveform = wlanWaveformGenerator(1,cfgHE);
Obtain the WLAN field indices, which contain the modulated HE-SIG-A symbols.
ind = wlanFieldIndices(cfgHE); rxSIGA = waveform(ind.HESIGA(1):ind.HESIGA(2),:);
Perform OFDM demodulation to extract the HE-SIG-A field.
sigaDemod = wlanHEDemodulate(rxSIGA,'HE-SIG-A',cbw);
Return the pre-HE OFDM information and extract the demodulated HE-SIG-A symbols.
preHEInfo = wlanHEOFDMInfo('HE-SIG-A',cbw);
siga = sigaDemod(preHEInfo.DataIndices,:);
Specify the channel state information and assume no channel noise.
csi = ones(52,1); noiseVarEst = 0;
Recover the HE-SIG-A information bits and other information. Display the CRC result.
[bits,failCRC] = wlanHESIGABitRecover(siga,noiseVarEst,csi); disp(failCRC);
0
Update HE MU Recovery Configuration Object
Update a WLAN HE recovery configuration object by interpreting recovered HE-SIG-A and HE-SIG-B information bits.
Generate HE MU Waveform
Create a WLAN HE MU configuration object, setting the allocation index to 0
.
cfgHEMU = wlanHEMUConfig(0);
Generate a WLAN waveform and PPDU field indices for the specified configuration.
waveform = wlanWaveformGenerator(1,cfgHEMU); ind = wlanFieldIndices(cfgHEMU);
Recover L-SIG Bits
Create a WLAN recovery configuration object, specifying an HE MU packet format and the length of the L-SIG field.
cfg = wlanHERecoveryConfig('PacketFormat','HE-MU','ChannelBandwidth','CBW20');
Decode the L-SIG field and obtain the orthogonal frequency-division multiplexing (OFDM) information. The recovery configuration object requires this information to obtain the L-SIG length.
lsig = waveform(ind.LSIG(1):ind.LSIG(2)); lsigDemod = wlanHEDemodulate(lsig,'L-SIG',cfg.ChannelBandwidth); info = wlanHEOFDMInfo('L-SIG',cfg.ChannelBandwidth); lsigDemod = lsigDemod(info.DataIndices,:);
Recover the L-SIG bits and related information, making sure that the bits pass the parity check, and update the recovery configuration object with the L-SIG length. 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,0,csi); cfg.LSIGLength = lsigInfo.Length;
Update Recovery Configuration Object with HE-SIG-A Bits
Decode the HE-SIG-A field and recover the HE-SIG-A 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',cfg.ChannelBandwidth);
sigaDemod = sigaDemod(info.DataIndices,:);
[sigaBits,failCRC] = wlanHESIGABitRecover(sigaDemod,0,csi);
disp(failCRC)
0
Update the recovery configuration object with the recovered HE-SIG-A bits. Display the updated object. A property value of -1
or 'Unknown'
indicates an unknown or undefined property, which can be updated after decoding the HE-SIG-B common and user fields of the HE MU packet.
[cfg,failInterpretation] = interpretHESIGABits(cfg,sigaBits)
cfg = wlanHERecoveryConfig with properties: PacketFormat: 'HE-MU' ChannelBandwidth: 'CBW20' LSIGLength: 878 SIGBCompression: 0 SIGBMCS: 0 SIGBDCM: 0 NumSIGBSymbolsSignaled: 10 STBC: 0 LDPCExtraSymbol: 1 PreFECPaddingFactor: 1 PEDisambiguity: 0 GuardInterval: 3.2000 HELTFType: 4 NumHELTFSymbols: 1 UplinkIndication: 0 BSSColor: 0 SpatialReuse: 0 TXOPDuration: 127 HighDoppler: 0 AllocationIndex: -1 NumUsersPerContentChannel: -1 RUTotalSpaceTimeStreams: -1 RUSize: -1 RUIndex: -1 STAID: -1 MCS: -1 DCM: -1 ChannelCoding: 'Unknown' Beamforming: -1 NumSpaceTimeStreams: -1 SpaceTimeStreamStartingIndex: -1
failInterpretation = logical
0
Update Recovery Configuration Object with HE-SIG-B Common Field Bits
Decode the HE-SIG-B common field, ensuring that all content channels pass the CRC.
len = getSIGBLength(cfg);
sigbCommon = waveform(double(ind.HESIGA(2))+(1:len.NumSIGBCommonFieldSamples),:);
sigbCommonDemod = wlanHEDemodulate(sigbCommon,'HE-SIG-B',cfgHEMU.ChannelBandwidth);
sigbCommonDemod = sigbCommonDemod(info.DataIndices);
[sigbCommonBits,status,~] = wlanHESIGBCommonBitRecover(sigbCommonDemod,0,csi,cfg);
disp(status)
Success
Update the recovery configuration object with the recovered HE-SIG-B common field bits and display the updated object. A field returned as -1
or 'Unknown'
indicates an unknown or undefined property value, which can be updated after decoding the HE-SIG-B user field of the HE MU packet.
[cfg,failInterpretation] = interpretHESIGBCommonBits(cfg,sigbCommonBits,status)
cfg = wlanHERecoveryConfig with properties: PacketFormat: 'HE-MU' ChannelBandwidth: 'CBW20' LSIGLength: 878 SIGBCompression: 0 SIGBMCS: 0 SIGBDCM: 0 NumSIGBSymbolsSignaled: 10 STBC: 0 LDPCExtraSymbol: 1 PreFECPaddingFactor: 1 PEDisambiguity: 0 GuardInterval: 3.2000 HELTFType: 4 NumHELTFSymbols: 1 UplinkIndication: 0 BSSColor: 0 SpatialReuse: 0 TXOPDuration: 127 HighDoppler: 0 AllocationIndex: 0 NumUsersPerContentChannel: 9 RUTotalSpaceTimeStreams: -1 RUSize: -1 RUIndex: -1 STAID: -1 MCS: -1 DCM: -1 ChannelCoding: 'Unknown' Beamforming: -1 NumSpaceTimeStreams: -1 SpaceTimeStreamStartingIndex: -1
failInterpretation = logical
0
Update Recovery Configuration Object with HE-SIG-B User Field Bits
Decode the HE-SIG-B user field, ensuring that all users pass the CRC.
sigbUser = waveform(ind.HESIGB(1):ind.HESIGB(2));
sigbUserDemod = wlanHEDemodulate(sigbUser,'HE-SIG-B',cfgHEMU.ChannelBandwidth);
sigbUserDemod = sigbUserDemod(info.DataIndices,:);
[sigbUserBits,failCRC,~] = wlanHESIGBUserBitRecover(sigbUserDemod,0,csi,cfg);
disp(failCRC)
0 0 0 0 0 0 0 0 0
Update the recovery configuration object with the recovered HE-SIG-B user field bits.
[user,failInterpretation] = interpretHESIGBUserBits(cfg,sigbUserBits,failCRC);
Display the results of interpretation and the third element of the user
output.
disp(failInterpretation)
0 0 0 0 0 0 0 0 0
disp(user{3})
wlanHERecoveryConfig with properties: PacketFormat: 'HE-MU' ChannelBandwidth: 'CBW20' LSIGLength: 878 SIGBCompression: 0 SIGBMCS: 0 SIGBDCM: 0 NumSIGBSymbolsSignaled: 10 STBC: 0 LDPCExtraSymbol: 1 PreFECPaddingFactor: 1 PEDisambiguity: 0 GuardInterval: 3.2000 HELTFType: 4 NumHELTFSymbols: 1 UplinkIndication: 0 BSSColor: 0 SpatialReuse: 0 TXOPDuration: 127 HighDoppler: 0 AllocationIndex: 0 NumUsersPerContentChannel: 9 RUTotalSpaceTimeStreams: 1 RUSize: 26 RUIndex: 3 STAID: 0 MCS: 0 DCM: 0 ChannelCoding: 'LDPC' Beamforming: 0 NumSpaceTimeStreams: 1 SpaceTimeStreamStartingIndex: 1
Input Arguments
siga
— Demodulated HE-SIG-A symbols
complex-valued matrix
Demodulated HE-SIG-A symbols, specified as a complex-valued matrix. The size of
siga
depends on the packet format.
For high-efficiency single-user (HE SU) or high-efficiency multiuser (HE MU) packets, specify a 52-by-2 matrix.
For high-efficiency extended-range single-user (HE ER SU) packets, specify a 52-by-4 matrix.
Data Types: single
| double
Complex Number Support: Yes
noiseVarEst
— Channel noise variance estimate
nonnegative scalar
Channel noise variance estimate, specified as a nonnegative scalar.
Data Types: single
| double
csi
— Channel state information
52-by-1 real-valued vector
Channel state information, specified as a 52-by-1 real-valued vector. To use the channel state information for enhanced demapping of the orthogonal frequency-division multiplexing (OFDM) symbols, specify this argument.
Data Types: single
| double
Output Arguments
bits
— Information bits recovered from HE-SIG-A field
52-by-1 binary column vector
Information bits recovered from HE-SIG-A field, returned as a 52-by-1 binary column vector.
Data Types: int8
failCRC
— CRC result
1
(true
) | 0
(false
)
CRC result, returned as a logical value of 1
(true
) or 0
(false
). The
function returns this argument as 1
(true
) if the
recovered bits fail the CRC. The function returns this argument as 0
(false
) if the recovered bits pass the CRC.
Data Types: logical
References
[1] IEEE Std 802.11-2020 (Revision of IEEE Std 802.11-2016). “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.” IEEE Standard for Information Technology — Telecommunications and Information Exchange between Systems — Local and Metropolitan Area Networks — Specific Requirements.
[2] IEEE Std 802.11ax-2021 (Amendment to IEEE Std 802.11-2020). “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Amendment 1: Enhancements for High Efficiency WLAN.” IEEE Standard for Information Technology — Telecommunications and Information Exchange between Systems. Local and Metropolitan Area Networks — Specific Requirements.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2019a
See Also
Functions
wlanFieldIndices
|wlanHEDataBitRecover
|wlanHESIGBCommonBitRecover
|wlanHESIGBUserBitRecover
|wlanLSIGBitRecover
Objects
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