wlanNonHTData

Generate non-HT-Data field waveform

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Syntax

y = wlanNonHTData(psdu,cfg)
y = wlanNonHTData(psdu,cfg,scramInit)

Description

example

y = wlanNonHTData(psdu,cfg) generates the non-HT-Data field[1] time-domain waveform for the input PSDU bits.

y = wlanNonHTData(psdu,cfg,scramInit) uses scramInit for the scrambler initialization state.

Examples

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Open Live Script

Generate the waveform for a 20MHz non-HT-Data field for 36 Mbps.

Create a non-HT configuration object and assign MCS to 5.

cfg = wlanNonHTConfig('MCS',5);

Assign random data to the PSDU and generate the data field waveform.

psdu = randi([0 1],cfg.PSDULength*8,1);
y = wlanNonHTData(psdu,cfg);
size(y)
ans = 1×2

        4480           1

Input Arguments

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PLCP service data unit (PSDU), specified as an Nbits-by-1 vector, where Nbits = PSDULength × 8. PSDU vector can range from 1 byte to 4095 bytes, as specified by PSDULength.

Data Types: double

Format configuration, specified as a wlanNonHTConfig object.

Scrambler initialization state for each packet generated, specified as an integer in the interval [1, 127] or as the corresponding binary vector of length seven. The default value of 93 is the example state given in IEEE Std 802.11™-2012, Section L.1.5.2.

The scrambler initialization used on the transmission data follows the process described in IEEE® Std 802.11-2012, Section 18.3.5.5 and IEEE Std 802.11ad™-2012, Section 21.3.9. The header and data fields that follow the scrambler initialization field (including data padding bits) are scrambled by XORing each bit with a length-127 periodic sequence generated by the polynomial S(x) = x7+x4+1. The octets of the PSDU (Physical Layer Service Data Unit) are placed into a bit stream, and within each octet, bit 0 (LSB) is first and bit 7 (MSB) is last. The generation of the sequence and the XOR operation are shown in this figure:

Conversion from integer to bits uses left-MSB orientation. For the initialization of the scrambler with decimal 1, the bits are mapped to the elements shown.

ElementX7X6X5X4X3X2X1
Bit Value0000001

To generate the bit stream equivalent to a decimal, use de2bi. For example, for decimal 1:

de2bi(1,7,'left-msb')
ans =

     0     0     0     0     0     0     1

Example: [1; 0; 1; 1; 1; 0; 1] conveys the scrambler initialization state of 93 as a binary vector.

Data Types: double | int8

Output Arguments

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Non-HT-Data field time-domain waveform, returned as an NS-by-NT matrix. NS is the number of time domain samples, and NT is the number of transmit antennas.

More About

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PSDU

Physical layer convergence procedure (PLCP) service data unit (PSDU). This field is composed of a variable number of octets. The minimum is 0 (zero) and the maximum is 2500. For more information, see IEEE Std 802.11™-2012, Section 15.3.5.7.

non-HT-Data field

The non-high throughput data (non-HT data) field is used to transmit MAC frames and is composed of a service field, a PSDU, tail bits, and pad bits.

  • Service field — Contains 16 zeros to initialize the data scrambler.

  • PSDU — Variable-length field containing the PLCP service data unit (PSDU).

  • Tail — Tail bits required to terminate a convolutional code. The field uses six zeros for the single encoding stream.

  • Pad Bits — Variable-length field required to ensure that the non-HT data field contains an integer number of symbols.

Algorithms

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non-HT-Data Field Processing

The non-HT-Data field follows the L-SIG in the packet structure. For algorithm details, refer to IEEE Std 802.11-2012 [1], Section 18.3.5. The non-HT-Data field includes the user payload in the PSDU plus 16 service bits, 6 tail bits, and additional padding bits as required to fill out the last OFDM symbol. The wlanNonHTData function performs transmitter processing on the non-HT-Data field and outputs the time-domain waveform.

References

[1] IEEE Std 802.11™-2012 IEEE Standard for Information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.

Extended Capabilities

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

See Also

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Introduced in R2015b

[1] IEEE Std 802.11-2012 Adapted and reprinted with permission from IEEE. Copyright IEEE 2012. All rights reserved.

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