wlanAPEPLength

Calculate APEP length in octets

Syntax

APEPLength = wlanAPEPLength(cfgPHY,unit,value)

Description

APEPLength = wlanAPEPLength(cfgPHY,unit,value) returns APEPLength, the aggregate MAC protocol data unit (A-MPDU) pre-EOF padding (APEP) length, in octets from the given value and the physical layer configuration, cfgPHY. The units of value can be in terms of physical layer conformance procedure (PLCP) protocol data unit (PPDU) transmission time or number of data symbols, specified by the unit input argument.

Examples

Generate VHT Waveform with Specified Transmission Time

Create a wlanVHTConfig object, 'cfgPHY', and specify the transmission time, 'txTime', in microseconds.

cfgPHY = wlanVHTConfig;
txTime = 200;

Calculate the APEP length in octets.

apepLength = wlanAPEPLength(cfgPHY,'TxTime',txTime)

apepLength = 
580

Set the number of bytes carried in the user payload for the configuration object, 'cfgPHY', to this APEP length.

cfgPHY.APEPLength = apepLength;

Create a wlanMACFrameConfig object, 'cfgMAC'. Use this object to generate a VHT-format QoS data frame.

cfgMAC = wlanMACFrameConfig('FrameType','QoS Data', ...
    'FrameFormat','VHT');

Calculate the MAC service data unit (MSDU) lengths required to generate a MAC frame of size 'APEPLength'.

msduLengths = wlanMSDULengths(apepLength,cfgMAC,cfgPHY);

Create random MSDUs using 'msduLengths'.

msduList = cell(1, numel(msduLengths));
for i = 1:numel(msduLengths)
    msduList{i} = randi([0 255],1,msduLengths(i));
end

Generate MAC frame bits using the MSDUs, 'msduList'.

macFrameBits = wlanMACFrame(msduList,cfgMAC,cfgPHY,'OutputFormat','bits');

Generate a VHT waveform using 'cfgPHY' and the generated MAC frame bits, 'macFrameBits'.

waveform = wlanWaveformGenerator(macFrameBits,cfgPHY);

Generate HE-SU Waveform with Specified Number of Data Symbols

Create a wlanHESUConfig object, 'cfgPHY'.

cfgPHY = wlanHESUConfig;

Calculate the APEP length in octets, specifying 200 data symbols.

apepLength = wlanAPEPLength(cfgPHY,'NumDataSymbols',200)

apepLength = 
2920

Set the number of bytes carried in the user payload for the configuration object, 'cfgPHY', to this APEP length. Calculate the PSDU length.

cfgPHY.APEPLength = apepLength;
psduLength = getPSDULength(cfgPHY)*8;

Create a random PSDU, 'psdu', using the calculated PSDU length.

psdu = randi([0 1],getPSDULength(cfgPHY)*8,1);

Generate an HE-SU waveform using 'cfgPHY' and 'psdu'.

waveform = wlanWaveformGenerator(psdu,cfgPHY);

Input Arguments

cfgPHY — PHY format configuration

wlanEHTMUConfig object | wlanHESUConfig object | wlanVHTConfig object

PHY format configuration, specified as a wlanEHTMUConfig, wlanHESUConfig, or wlanVHTConfig object. This object defines a PHY format configuration and its applicable properties.

Note

When you specify this input as a wlanEHTMUConfig object, it must be single-user.

unit — Units of argument value

'TxTime' | 'NumDataSymbols'

Units of the argument value, specified as one of 'TxTime' or 'NumDataSymbols'. This value indicates the units of value from which the APEP length is calculated.

Data Types: char | string

value — Value from which APEP length is calculated

numeric scalar

Value from which the APEP length is calculated, specified as a numeric scalar. Input argument unit specifies the unit of value. This table describes how the function interprets value based on unit.

unit Value	value Description
'TxTime'	Scalar number specifying the time in microseconds
'NumDataSymbols'	Scalar number specifying the number of data symbols

Data Types: double

Output Arguments

APEPLength — Length of APEP

numeric scalar

Length of the APEP, in octets, returned as a numeric scalar. This value returns the maximum APEP length that fits into the specified value of 'TxTime' or 'NumDataSymbols'.

Data Types: double

Extended Capabilities

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

Version History

Introduced in R2019b

R2024b: Calculate APEP length for EHT SU configurations

You can now calculate the maximum APEP length for EHT single-user configurations. To use this feature, specify the cfgPHY input as a wlanEHTMUConfig object that has one user.

R2024b: Exceeding TxTime limit for symbol boundary no longer causes error

When you specify unit as 'TxTime' and the value you specify makes the transmit time that corresponds to the next symbol boundary higher than the maximum allowed, the function returns the APEP length that corresponds to the highest valid transmit time. Previously, the function threw an error in this case.