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wlanPreEHTChannelEstimate

Channel estimation using pre-EHT fields

Since R2023b

Description

chEst = wlanPreEHTChannelEstimate(demodSym,chEstLLTF,cbw) returns the channel estimate at the legacy signal field (L-SIG) using the demodulated L-SIG field symbols, demodSym, and the channel estimate at the legacy long training field (L-LTF), chEstLLTF. The channel bandwidth is specified in cbw. For more information about these fields, see L-SIG and L-LTF.

example

chEst = wlanPreEHTChannelEstimate(___,span) specifies the span of a moving-average filter in addition to the input arguments in the previous syntax. The function uses this filter to perform frequency smoothing.

example

Examples

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Create an EHT MU configuration object with a channel bandwidth of 20 MHz. Generate a time-domain waveform for the configuration.

cfg = wlanEHTMUConfig("CBW20");
cbw = cfg.ChannelBandwidth;
txSig = wlanWaveformGenerator([1;0;0;1],cfg);

Pass the signal through an AWGN channel with a signal-to-noise ratio of 20 dB.

rxSig = awgn(txSig,20);

Get the field indices of the configuration, demodulate the L-LTF, and perform L-LTF channel estimation.

ind = wlanFieldIndices(cfg);
demodSigLLTF = wlanEHTDemodulate(rxSig(ind.LLTF(1):ind.LLTF(2),:),"L-LTF",cfg);
chEstLLTF = wlanLLTFChannelEstimate(demodSigLLTF,cbw);

Demodulate the L-SIG and RL-SIG fields.

demodSigLSIG = wlanEHTDemodulate(rxSig(ind.LSIG(1):ind.RLSIG(2),:),"L-SIG",cfg);

Using a frequency smoothing span of 5, perform the full channel estimation.

est = wlanPreEHTChannelEstimate(demodSigLSIG,chEstLLTF,cbw,5);

Display the absolute value of the channel estimate.

imagesc(abs(est.'))
title("Absolute Value of Channel Estimate")
xlabel("Subcarriers")
set(gca,YTickLabels=[])
colorbar

Figure contains an axes object. The axes object with title Absolute Value of Channel Estimate, xlabel Subcarriers contains an object of type image.

Input Arguments

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Demodulated L-SIG field symbols, specified as an NST-by-NSYM-by-NR array. NST is the number of occupied subcarriers. NSYM is the number of OFDM symbols in the L-SIG and repeated legacy signal (RL-SIG) fields. NR is the number of receive antennas.

Data Types: single | double
Complex Number Support: Yes

Channel estimate at the legacy long training field, specified as an NST-by-1-by-NR array. NST is the number of occupied subcarriers and NR is the number of receive antennas.

Data Types: single | double
Complex Number Support: Yes

Channel bandwidth, specified as one of these values.

  • "CBW20" — Channel bandwidth of 20 MHz

  • "CBW40" — Channel bandwidth of 40 MHz

  • "CBW80" — Channel bandwidth of 80 MHz

  • "CBW160" — Channel bandwidth of 160 MHz

  • "CBW320" — Channel bandwidth of 320 MHz

Data Types: char | string

Span of the frequency smoothing filter, specified as a positive odd integer and expressed as a number of subcarriers. The function applies frequency smoothing only when span is greater than one. For more information on when to specify this input, see Frequency Smoothing.

Data Types: double

Output Arguments

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Channel estimate at all data and pilot subcarriers, returned as an NST-by-1-by-NR array. NST is the number of occupied subcarriers and NR is the number of receive antennas. The output includes the channel estimates for the extra four subcarriers per each 20 MHz subchannel in the L-SIG field.

More About

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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.

[3] IEEE P802.11be™/D5.0. “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Amendment 8: Enhancements for Extremely High Throughput (EHT).” Draft Standard for Information Technology — Telecommunications and Information Exchange between Systems — Local and Metropolitan Area Networks — Specific Requirements, https://ieeexplore.ieee.org/document/10381585

Extended Capabilities

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

Version History

Introduced in R2023b