Generate HT-Data field waveform
Generate the waveform signal for a 40 MHz HT-mixed data field with multiple transmit antennas. Create an HT format configuration object. Specify 40 MHz channel bandwidth, two transmit antennas, and two space-time streams.
cfgHT = wlanHTConfig('ChannelBandwidth','CBW40','NumTransmitAntennas',2,'NumSpaceTimeStreams', 2,'MCS',12)
cfgHT = wlanHTConfig with properties: ChannelBandwidth: 'CBW40' NumTransmitAntennas: 2 NumSpaceTimeStreams: 2 SpatialMapping: 'Direct' MCS: 12 GuardInterval: 'Long' ChannelCoding: 'BCC' PSDULength: 1024 AggregatedMPDU: 0 RecommendSmoothing: 1
PSDULength bytes of random data to a bit stream and generate the HT data waveform.
PSDU = randi([0 1],cfgHT.PSDULength*8,1); y = wlanHTData(PSDU,cfgHT);
Determine the size of the waveform.
ans = 1×2 2080 2
The function returns a complex two-column time-domain waveform. Each column contains 2080 samples, corresponding to the HT-Data field for each transmit antenna.
The HT-Data field follows the last HT-long training field (HT-LTF) of an HT-mixed packet.
The HT-Data field is carries one or more frames from the medium access control (MAC) layer and consists of four subfields.
Service — Contains 16 zeros to initialize the data scrambler
PSDU — Variable-length field containing a PLCP service data unit (PSDU)
Tail — Contains six zeros for each encoding stream, required to terminate a convolutional code
Pad Bits — Variable-length field required to ensure that the HT-Data field consists of an integer number of symbols
Physical layer (PHY) 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 22.214.171.124.
The HT-Data field follows the last HT-LTF in the packet structure.
The HT-Data field includes the user payload in the PSDU, plus 16 service bits, 6 × NES tail bits, and additional padding bits as required to fill out the last OFDM symbol.
For algorithm details, refer to IEEE Std 802.11™-2012 , Section 20.3.11.
wlanHTData function performs transmitter
processing on the HT-Data field and
outputs the time-domain waveform for NT transmit
|NES is the number of BCC encoders.|
|NSS is the number of spatial streams.|
|NSTS is the number of space-time streams.|
|NT is the number of transmit antennas.|
BCC channel coding is shown. STBC and spatial mapping are optional modes for HT format.
 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.
 IEEE Std 802.11-2012 Adapted and reprinted with permission from IEEE. Copyright IEEE 2012. All rights reserved.