wlanReferenceSymbols

Reference symbols of constellation diagram

Syntax

refSym = wlanReferenceSymbols(mod)

refSym = wlanReferenceSymbols(mod,phase)

refSym = wlanReferenceSymbols(cfg)

refSym = wlanReferenceSymbols(cfg,userNumber)

Description

refSym = wlanReferenceSymbols(mod) returns the reference symbols of the constellation diagram for the specified modulation scheme.

refSym = wlanReferenceSymbols(mod,phase) returns reference symbols with counterclockwise rotation for the specified modulation scheme.

refSym = wlanReferenceSymbols(cfg) returns the reference symbols used in the data field of a single-user (SU) transmission or a recovered high-efficiency (HE) transmission parameterized by the configuration object cfg.

refSym = wlanReferenceSymbols(cfg,userNumber) returns the reference symbols used in the data field for the user specified by userNumber in a multiuser (MU) transmission specified by MU configuration object cfg.

Examples

Plot Noisy QPSK Constellation with Reference Symbols

Fine reference symbols for a quadrature phase-shift keying (QPSK) modulation scheme and plot the resulting constellation.

Generate noisy QPSK symbols.

sym =  awgn(qammod(randi([0 3],100,1),4)/sqrt(2),20);

Find the reference symbols.

refSym =  wlanReferenceSymbols('QPSK');

Plot the constellation diagram.

figure;
plot(sym,'b.');
hold on;
plot(refSym,'ro');
title('Noisy QPSK Constellation with Reference Symbols');
legend('Noisy symbols','Reference symbols','Location','South');

Find Reference Symbols with Counterclockwise Rotation

Find reference symbols for a chosen modulation scheme and counterclockwise rotation.

Reference Symbols for $\frac{\pi }{2}$-BPSK

Specify a $\frac{\pi }{2}$-BPSK modulation scheme and a counterclockwise rotation of $\frac{\pi }{6}$.

mod = 'pi/2-BPSK';
phase =  pi/6;

Find the reference symbols for the chosen modulation and rotation.

refSym = wlanReferenceSymbols(mod,phase);

Display the reference symbols on a constellation diagram.

figure;
plot(refSym,'b*');
hold on;
title('Reference Symbols for $\frac{\pi}{2}$-BPSK','Interpreter','latex');
legend('Reference symbols');

Reference Symbols for $\frac{\pi }{2}$-16-QAM

Specify a $\frac{\pi }{2}$-16-QAM modulation scheme and a counterclockwise rotation of $\frac{\pi }{3}$.

mod = 'pi/2-16QAM';
phase =  pi/3;

Find the reference symbols for the chosen modulation and rotation.

refSym = wlanReferenceSymbols(mod,phase);

Display the reference symbols on a constellation diagram.

figure;
plot(refSym,'b*');
hold on;
title('Reference Symbols for $\frac{\pi}{2}$-16-QAM','Interpreter','latex');
legend('Reference symbols');

Plot Reference Constellation for User in VHT Configuration

Plot the reference constellation for a user in a very-high-throughput (VHT) multiuser configuration.

Create a VHT-format configuration object, setting channel bandwidth, number of users, group identifier, number of transmit antennas, number of space-time streams, and modulation and coding schemes.

cfg = wlanVHTConfig('ChannelBandwidth','CBW20','NumUsers',2,'GroupID',2, ...
    'NumTransmitAntennas',2,'NumSpaceTimeStreams',[1 1],'MCS',[8 4]);

Find the reference symbols for both users and plot the constellations.

refSym1 = wlanReferenceSymbols(cfg,1);
refSym2 = wlanReferenceSymbols(cfg,2);
figure;
plot(refSym1,'b*'); hold on
plot(refSym2,'ro');
title('Reference Constellations for Both Users')
legend('User 1','User 2','Location','bestoutside');

Input Arguments

mod — Modulation scheme

'BPSK' | 'pi/2-BPSK' | 'QPSK' | 'pi/2-QPSK' | '16QAM' | 'pi/2-16QAM' | '64QAM' | 'pi/2-64QAM' | '256QAM' | '1024QAM' | '4096QAM'

Modulation scheme, specified as one of these values.

• 'BPSK' — Binary phase-shift keying (BPSK)

• 'pi/2-BPSK' — π/2-BPSK

• 'QPSK' — Quadrature phase-shift keying (QPSK)

• 'pi/2-QPSK' — π/2-QPSK

• '16QAM' — 16-point quadrature amplitude modulation (16-QAM)

• 'pi/2-16QAM' — π/2-16-QAM

• '64QAM' — 64-QAM

• 'pi/2-64QAM' — π/2-64-QAM

• '256QAM' — 256-QAM

• '1024QAM' — 1024-QAM

• '4096QAM' — 4096-QAM

Data Types: char | string

phase — Counterclockwise rotation in radians

real-valued scalar (default) | real-valued row vector

Counterclockwise rotation in radians, specified as a real-valued scalar or real-valued row vector. To return reference symbols for different phases, specify phase as a row vector. Each vector element represents a chosen phase.

Data Types: double

cfg — PHY format configuration

wlanEHTTBConfig object | wlanEHTMUConfig object | wlanEHTRecoveryConfig object | wlanHESUConfig object | wlanHEMUConfig object | wlanHETBConfig object | wlanHERecoveryConfig object | wlanDMGConfig object | wlanS1GConfig object | wlanVHTConfig object | wlanHTConfig object | wlanNonHTConfig object

Physical layer (PHY) format configuration, specified as one of these objects: wlanEHTTBConfig, wlanEHTMUConfig, wlanEHTRecoveryConfig, wlanHESUConfig, wlanHEMUConfig, wlanHETBConfig, wlanHERecoveryConfig, wlanDMGConfig, wlanS1GConfig, wlanVHTConfig, wlanHTConfig, or wlanNonHTConfig.

userNumber — Number assigned to user of interest

1 (default) | positive integer

Number assigned to user of interest, specified as a positive integer in the interval [1, N_u], where N_u is the number of users in the transmission.

This argument is required when you specify the cfg input as an object of type wlanHEMUConfig, wlanS1GConfig, or wlanVHTConfig.

When you specify cfg as a wlanEHTMUConfig object,

• this argument is required if the PPDU type is OFDMA, or non-OFDMA with multiple users.

• this argument is not required for a non-OFDMA PPDU with a single user.

If cfg is a wlanHEMUConfig or wlanEHTMUConfig object, N_u is equal to the number of elements in the value of its User property. If cfg is a wlanS1GConfig or wlanVHTConfig object, N_u is equal to the value of its NumUsers property.

Dependencies

This argument applies only when the cfg input is an object of type wlanEHTMUConfig, wlanHEMUConfig, wlanS1GConfig, or wlanVHTConfig.

Data Types: double

Output Arguments

refSym — Reference symbols of constellation diagram

complex-valued column vector

Reference symbols of constellation diagram, returned as a complex-valued column vector.

Data Types: double
Complex Number Support: Yes

Extended Capabilities

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

Version History

Introduced in R2019a

R2024b: Generate C/C++ code for EHT blind recovery

You can now generate C and C++ code using MATLAB^® Coder™ when you specify the cfg input as a wlanEHTRecoveryConfig object.

R2023b: EHT TB and recovery reference symbols

You can specify cfg as an object of type wlanEHTTBConfig or wlanEHTRecoveryConfig.

R2023a: EHT MU reference symbols

You can specify cfg as an object of type wlanEHTMUConfig.