wlanVHTConfig

Configure VHT transmission

Description

The wlanVHTConfig object is a configuration object for the WLAN very high throughput (VHT) packet format.

Creation

Syntax

cfgVHT = wlanVHTConfig

cfgVHT = wlanVHTConfig(Name,Value)

Description

cfgVHT = wlanVHTConfig creates a configuration object that initializes parameters for an IEEE^® 802.11™ VHT PPDU.

cfgVHT = wlanVHTConfig(Name,Value) sets properties using one or more name-value pairs. Enclose each property name in quotation marks. For example, wlanVHTConfig('GuardInterval','Short') specifies a 400-nanosecond guard interval (cyclic prefix) duration.

At runtime, the calling function validates object settings for properties relevant to the operation of the function.

Properties

ChannelBandwidth — Channel bandwidth of PPDU transmission

'CBW80' (default) | 'CBW20' | 'CBW40' | 'CBW160'

Channel bandwidth of PPDU transmission, 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

Data Types: char | string

NumUsers — Number of users

1 (default) | 2 | 3 | 4

Number of users, specified as 1, 2, 3, or 4.

Data Types: double

UserPositions — User positions

[0 1] (default) | vector of integers

User positions, specified as a 1-by-NumUsers vector of integers in the interval [0, 3] in strictly increasing order.

Example: [0 2 3] specifies the positions for three users. The first user occupies position 0, the second user occupies position 2, and the third user occupies position 3.

Dependencies

This property applies only when you specify the NumUsers property as a value greater than 1.

Data Types: double

NumTransmitAntennas — Number of transmit antennas

1 (default) | positive integer

Number of transmit antennas, specified as a positive integer.

Data Types: double

PreVHTCyclicShifts — Cyclic shift values of additional transmit antennas

-75 (default) | integer in the interval [–200, 0] | row vector

Cyclic shift values, in nanoseconds, of additional transmit antennas for the pre-VHT fields of the waveform. The first eight antennas use the cyclic shift values specified in Table 21-10 of [1]. The remaining L antennas use the values you specify in this property, where L = NumTransmitAntennas – 8. Specify this property as one of these values:

• An integer in the interval [–200, 0] – the wlanVHTConfig object uses this cyclic shift value for each of the L additional antennas.

• A row vector of length L of integers in the interval [–200, 0] – the wlanVHTConfig object uses the kth element as the cyclic shift value for the (k + 8)th transmit antenna.

  Note

  If you specify this property as a row vector of length greater than L, the wlanVHTConfig object uses only the first L elements. For example, if you set the NumTransmitAntennas property to 16, the wlanVHTConfig object uses only the first L= 16 – 8 = 8 elements of this vector.

Dependencies

To enable this property, set the NumTransmitAntennas property to a value greater than 8.

Data Types: double

NumSpaceTimeStreams — Number of space-time streams

1 (default) | integer in the interval [1, 8] | vector of integers in the interval [1, 4]

Number of space-time streams in the transmission, specified as one of these values:

• An integer in the interval [1, 8], applicable when the NumUsers property is 1

• A 1-by-NumUsers vector of integers in the interval [1, 4], applicable when the NumUsers property is greater than 1.

Example: [1 3 2] is the number of space-time streams for each user in a three-user transmission.

Note

The sum of the elements of this property must not exceed eight.

Data Types: double

SpatialMapping — Spatial mapping scheme

'Direct' (default) | 'Hadamard' | 'Fourier' | 'Custom'

Spatial mapping scheme, specified as 'Direct', 'Hadamard', 'Fourier', or 'Custom'.

Dependencies

The default value, 'Direct', applies only when you set the NumTransmitAntennas and NumSpaceTimeStreams properties to the same value.

Data Types: char | string

SpatialMappingMatrix — Spatial mapping matrix

1 (default) | complex-valued scalar | complex-valued matrix | complex-valued 3-D array

Spatial mapping matrix, specified as one of these values:

• A complex-valued scalar. This value applies to all the subcarriers.

• A complex-valued matrix of size N_STS -by-N_T, where:

  • N_STS is the number of space-time streams;

  • N_T is the number of transmit antennas.

  In this case, the spatial mapping matrix applies to all the subcarriers.

• A complex-valued 3-D array of size N_ST-by-N_STS-by-N_T, where N_ST is the number of occupied subcarriers. The value of N_ST is the number of occupied subcarriers. The ChannelBandwidth property determines the value of N_ST. In this case, each occupied subcarrier has its own spatial mapping matrix.

  This table shows the ChannelBandwidth setting and the corresponding N_ST:

  ChannelBandwidth	Number of Occupied Subcarriers, NST	Number of Data Subcarriers	Number of Pilot Subcarriers
  'CBW20'	56	52	4
  'CBW40'	114	108	6
  'CBW80'	242	234	8
  'CBW160'	484	468	16

Use this property to rotate and scale the output vector of the constellation mapper. The spatial mapping matrix is used for beamforming and mixing space-time streams over the transmit antennas. For more information, see Section 19.3.11.11.2 of [1]. The calling function normalizes the spatial mapping matrix for each subcarrier.

Example: [0.5 0.3; 0.4 0.4; 0.5 0.8] represents a spatial mapping matrix with three space-time streams and two transmit antennas.

Dependencies

This property applies only when you set the SpatialMapping property to 'Custom'.

Data Types: double
Complex Number Support: Yes

Beamforming — Enable beamforming

true or 1 (default) | false or 0

Enable beamforming, specified as a numeric or logical value of 1 (true) or 0 (false). To apply a beamforming steering matrix, set this property to 1 (true). The SpatialMappingMatrix property specifies the beamforming steering matrix.

Dependencies

This property applies only when the NumUsers property is set to 1 and the SpatialMapping property is set to 'Custom'.

Data Types: logical

STBC — Enable STBC

false or 0 (default) | true or 1

Enable space-time block coding (STBC) of the PPDU data field, specified as a numeric or logical value of 1 (true) or 0 (false). STBC transmits multiple copies of the data stream across assigned antennas.

• When you set this property to 0 (false), STBC is not applied to the data field. The number of space-time streams is equal to the number of spatial streams.

• When you set this property to 1 (true), STBC is applied to the data field. The number of space-time streams is twice the number of spatial streams.

For more information, see Section 22.3.10.9.4 of

Dependencies

This property applies only when the NumUsers property is 1.

Data Types: logical

MCS — Modulation and coding scheme used for transmission

0 (default) | integer in the interval [0, 9] | vector of integers

Modulation and coding scheme used for transmission, specified as one of these values:

• an integer in the interval [0, 9], applicable when the NumUsers property is 1

• a 1-by-NumUsers vector of integers in the interval [0, 9], applicable when the NumUsers property is greater than 1.

This table shows the modulation type and coding rate for each valid value of MCS:

MCS	Modulation	Coding Rate
0	Binary phase-shift keying (BPSK)	1/2
1	Quadrature phase-shift keying (QPSK)	1/2
2	QPSK	3/4
3	16-point quadrature amplitude modulation (16-QAM)	1/2
4	16-QAM	3/4
5	64-QAM	2/3
6	64-QAM	3/4
7	64-QAM	5/6
8	256-QAM	3/4
9	256-QAM	5/6

Data Types: double

ChannelCoding — FEC coding type

'BCC' (default) | 'LDPC' | cell array of character vectors | cell array of strings

Forward-error-correction (FEC) coding type for the VHT-Data field, specified as one of these values:

• 'LDPC' – Low-density parity-check (LDPC) coding applies to all users in the transmission

• 'BCC' – binary convolutional coding (BCC) applies to all users in the transmission

• A 1-by-NumUsers cell array containing the values 'LDPC' and 'BCC', where the kth element specifies the channel coding for user k

For more information, see Section 21.3.10.5 of [1].

Data Types: char | cell | string

APEPLength — APEP length

1024 (default) | nonnegative integer | vector of nonnegative integers

Aggregated MPDU (A-MPDU) pre-end-of-frame (pre-EOF) padding (APEP) length, in bytes.

• When the NumUsers property is 1, specify this property as a nonnegative integer in the interval [0, 2²⁰ – 1].

• When the NumUsers property is a value other than 1, specify this property as a 1-by-NumUsers vector of integers in the interval [0, 2²⁰ – 1].

• For a null data packet (NDP), set this property to 0.

The wlanVHTConfig object uses this property to determine the number of OFDM symbols in the data field. For more information, see Table 21-1 of [1].

Note

This object supports only aggregated data transmission.

Data Types: double

PSDULength — PSDU length

integer in the interval [0, 2²⁰ – 1] | vector of integers in the interval [0, 2²⁰–1]

This property is read-only.

Physical layer convergence procedure (PLCP) service data unit (PSDU) length, in bytes, specified as one of these values:

• An integer in the interval [0, 2²⁰ – 1], applicable when the NumUsers property is 1. A value of 0 corresponds to a null data packet (NDP).

• A vector of integers in the interval [0, 2²⁰ – 1], applicable when the NumUsers property is greater than 1.

• An empty array, applicable when this property is undefined, for example, when the set of property values is invalid.

The wlanVHTConfig object calculates this property based on the value of the APEPLength property and other coding related properties. The details of this calculation are specified in Section 21.4.3 of [1].

Example: [1035 4150] is the PSDU length vector for a wlanVHTConfig object where the NumUsers property is 2 and the MCS property is [0 3].

Data Types: double

GuardInterval — Guard interval (cyclic prefix) duration

'Long' (default) | 'Short'

Guard interval (cyclic prefix) duration for the data field within a packet specified as one of these values:

• 'Long' – Guard interval duration of 800 ns

• 'Short' – Guard interval duration of 400 ns

Data Types: char | string

GroupID — Group identification number

63 (default) | integer in the interval [0, 63]

Group identification number, specified as an integer in the interval [0, 63].

Dependencies

The values 0 and 63 apply only when you set the NumUsers property to 1. Values in the interval [1, 62] apply only when you set the NumUsers property to a value other than 1.

Data Types: double

PartialAID — Abbreviated indication of PSDU recipients

275 (default) | integer in the interval [0, 511]

Abbreviated indication of the PSDU recipients, specified as an integer in the interval [0, 511].

• For an uplink transmission, the partial identification number is the last nine bits of the basic service set identifier (BSSID).

• For a downlink transmission, the partial identification number is an identifier that combines the association ID with the BSSID of its serving AP.

For more information, see Table 21-1 of [1].

Data Types: double

Examples

Create wlanVHTConfig Object for Single User

Create a VHT configuration object with the default settings.

cfgVHT = wlanVHTConfig

cfgVHT = 
  wlanVHTConfig with properties:

       ChannelBandwidth: 'CBW80'
               NumUsers: 1
    NumTransmitAntennas: 1
    NumSpaceTimeStreams: 1
         SpatialMapping: 'Direct'
                   STBC: 0
                    MCS: 0
          ChannelCoding: 'BCC'
             APEPLength: 1024
          GuardInterval: 'Long'
                GroupID: 63
             PartialAID: 275

   Read-only properties:
             PSDULength: 1035

Update the channel bandwidth.

cfgVHT.ChannelBandwidth = 'CBW40'

cfgVHT = 
  wlanVHTConfig with properties:

       ChannelBandwidth: 'CBW40'
               NumUsers: 1
    NumTransmitAntennas: 1
    NumSpaceTimeStreams: 1
         SpatialMapping: 'Direct'
                   STBC: 0
                    MCS: 0
          ChannelCoding: 'BCC'
             APEPLength: 1024
          GuardInterval: 'Long'
                GroupID: 63
             PartialAID: 275

   Read-only properties:
             PSDULength: 1030

Create wlanVHTConfig Object for Two Users

Create a VHT configuration object for a 20 MHz two-user transmission with one antenna per user.

Create a wlanVHTConfig object using a combination of name-value pairs and inline initialization to change default settings. Vector-valued properties apply user-specific settings.

cfgMU = wlanVHTConfig('ChannelBandwidth','CBW20','NumUsers',2, ...
    'GroupID',2,'NumTransmitAntennas',2);
cfgMU.NumSpaceTimeStreams = [1 1];
cfgMU.MCS = [4 8];
cfgMU.APEPLength = [1024 2048];
cfgMU.ChannelCoding = {'BCC' 'LDPC'}

cfgMU = 
  wlanVHTConfig with properties:

       ChannelBandwidth: 'CBW20'
               NumUsers: 2
          UserPositions: [0 1]
    NumTransmitAntennas: 2
    NumSpaceTimeStreams: [1 1]
         SpatialMapping: 'Direct'
                    MCS: [4 8]
          ChannelCoding: {'BCC'  'LDPC'}
             APEPLength: [1024 2048]
          GuardInterval: 'Long'
                GroupID: 2

   Read-only properties:
             PSDULength: [1030 2065]

The configuration object settings reflect the updates specified. Properties that aren't modified take their default values.

More About

PPDU

The physical layer (PHY) protocol data unit (PPDU) is the complete physical layer convergence procedure (PLCP) frame, including PLCP headers, MAC headers, the MAC data field, and the MAC and PLCP trailers.

References

[1] IEEE Std 802.11-2016 (Revision of IEEE Std 802.11-2012). “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.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations: After the first use of this object for a VHT MU-MIMO transmission, you cannot change the number of elements in any of these properties.

• UserPositions

• NumSpaceTimeStreams

• MCS

• ChannelCoding

• APEPLength

In addition, if you specify the ChannelCoding property as a cell array, you cannot change any of the elements of this property after the first use of this object for a VHT MU-MIMO transmission.