wlanhtltf
生成HT-LTF波形
Syntax
y = wlanHTLTF(cfg)
描述
例子
生成单流HT-LTF波形
创建一个wlanhtconfig
对象具有40 MHz的通道带宽。
cfg = wlanHTConfig(“ChannelBandwidth',“CBW40');
Generate the corresponding HT-LTF.
hltfout = wlanhtltf(cfg);size(hltfOut)
ans =1×2160 1
Thecfg
参数导致一个160个样本波形,只有一个与单个流传输相对应的列。
生成具有四个时空流的HT-LTF
生成具有四个传输天线和四个时空流的HT-LTF。
创建一个wlanhtconfig
对象具有31个MC,四个传输天线和四个时空流。
cfg = wlanHTConfig('MCS',31,'num Transmitantennas',4,“ numspacetimestreams”,4)
cfg = wlanhtconfig具有属性:channelbandwidth:'cbw20'num Transmitantennas:4 numspacetimestreams:4个空间映射:'Direct'MCS:31 GuardInterval:'Long'Long'Channel编码:'BCC'psdulength:'bcc'psdulength:1024聚合Mpdu:0推荐:0推荐:0推荐:1 1 1
Generate the corresponding HT-LTF.
hltfout = wlanhtltf(cfg);
验证HT-LTF输出是否由四个流(每个天线)组成。
size(hltfOut)
ans =1×2320 4
Because the channel bandwidth is 20 MHz and has four space-time streams, the output waveform has four HT-LTF and 320 time-domain samples.
Input Arguments
cfg
—格式配置
wlanhtconfig
object
格式配置,指定为wlanhtconfig
object. Thewlanhtltf
function uses these properties:
ChannelBandwidth
— Channel bandwidth
“CBW20'
(default) |“CBW40'
Channel bandwidth in MHz, specified as“CBW20'
或者“CBW40'
。
Data Types:char
|string
Num Transmitantennas
— Number of transmit antennas
1(默认)|2 |3| 4
发射天线的数量,指定为1、2、3或4。
Data Types:double
NumSpaceTimeStreams
— Number of space-time streams
1(默认)|2 |3| 4
Number of space-time streams in the transmission, specified as 1, 2, 3, or 4.
Data Types:double
numextensionsstreams
— Number of extension spatial streams
0(默认)|1 |2 |3
变速箱中的扩展空间流数量,指定为0、1、2或3。numextensionsstreams
大于0SpatialMapping
一定是'风俗'
。
Data Types:double
SpatialMapping
— Spatial mapping scheme
'Direct'
(default) |'Hadamard'
|'Fourier'
|'风俗'
空间映射方案,指定为'Direct'
,'Hadamard'
,'Fourier'
, or'风俗'
。默认值'Direct'
,适用于何时Num Transmitantennas
和NumSpaceTimeStreams
相等。
Data Types:char
|string
SpatialMappingMatrix
— Spatial mapping matrix
1(默认)|标量|矩阵|3-D阵列
Spatial mapping matrix, specified as a scalar, matrix, or 3-D array. Use this property to rotate and scale the constellation mapper output vector. This property applies when theSpatialMapping
属性设置为'风俗'
。The spatial mapping matrix is used for beamforming and mixing space-time streams over the transmit antennas.
什么时候specified as a scalar,
Num Transmitantennas
=NumSpaceTimeStreams
= 1,恒定值适用于所有子载波。什么时候specified as a matrix, the size must be (NSTS+NESS)-经过-NT。NSTSis the number of space-time streams.NESS是扩展空间流的数量。NT是发射天线的数量。空间映射矩阵适用于所有子载波。首先NSTS和lastNESSrows apply to the space-time streams and extension spatial streams respectively.
什么时候specified as a 3-D array, the size must beNST-经过-(NSTS+NESS)-经过-NT。NSTis the sum of the data and pilot subcarriers, as determined by
ChannelBandwidth
。NSTSis the number of space-time streams.NESS是扩展空间流的数量。NT是发射天线的数量。In this case, each data and pilot subcarrier can have its own spatial mapping matrix.The table shows the
ChannelBandwidth
设置和相应的NST。ChannelBandwidth
NST “CBW20'
56 “CBW40'
114
The calling function normalizes the spatial mapping matrix for each subcarrier.
例子:[0.5 0.3; 0.4 0.4; 0.5 0.8]
represents a spatial mapping matrix having three space-time streams and two transmit antennas.
Data Types:double
Complex Number Support:Yes
Output Arguments
y
- HT-LTF波形
matrix
HT-LTF waveform, returned as an (NS×NHTLTF)-经过-NTmatrix.NS是时间域样本的数量NHTLTF, whereNHTLTFis the number of OFDM symbols in theHT-LTF。NT是发射天线的数量。
NSis proportional to the channel bandwidth. Each symbol contains 80 time samples per 20 MHz channel.
ChannelBandwidth |
NS |
---|---|
“CBW20' |
80 |
“CBW40' |
160 |
确定数量NHTLTFis described inHT-LTF。
Data Types:double
Complex Number Support:Yes
More About
HT-LTF
The high throughput long training field (HT-LTF) is located between the HT-STF and data field of an HT-mixed packet.
As described in IEEE®STD 802.11™-2012,第20.3.9.4.6节,接收器可以使用HT-LTF来估计QAM映射器输出集(或应用STBC)之间的MIMO通道和接收链。HT-LTF部分有一个或两个部分。第一部分由一个,两个或四个HT-LTF组成,这些HT-LTF是解调PPDU的HT-DATA部分所必需的。这些HT-LTF被称为HT-DLTF。可选的第二部分由零,一,两个或四个HT-LTF组成,可用于在PPDU的HT-DATA部分使用的MIMO通道的额外空间尺寸。这些HT-LTF被称为HT-eltfs。每个HT长训练符号为4μs。时空流的数量和扩展流的数量决定了传输的HT-LTF符号的数量。
Tables 20-12, 20-13 and 20-14 from IEEE Std 802.11-2012 are reproduced here.
NSTS Determination |
Nhtdltf Determination |
Nhteltf Determination |
|||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Table 20-12 defines the number of space-time streams (NSTS) based on the number of spatial streams (NSS) from the MCS and the STBC field. |
Table 20-13 defines the number of HT-DLTFs required for theNSTS。 |
表20-14定义了扩展空间流数量所需的HT-teltf数量(NESS).NESSis defined in HT-SIG2。 |
|||||||||||||||||||||||||||||||||||||||||||||||
|
|
|
Additional constraints include:
NHTLTF=Nhtdltf+Nhteltf≤5。
NSTS+NESS≤4。
什么时候NSTS= 3,NESScannot exceed one.
如果NESS= 1whenNSTS= 3thenNHTLTF= 5。
HT-mixed
如IEEE STD 802.11-2012,第20.1.4节中所述,高吞吐量混合(HT混合)格式数据包包含与IEEE STD 802.11-2012,第18节和第19节接收器兼容的序言。非HT(第18和第19节)Stas可以解码非HT场(L-STF,L-LTF和L-SIG)。其余的前序场(HT-SIG,HT-STF和HT-LTF)用于HT传输,因此第18节和第19节Stas无法解码它们。该数据包的HT部分在IEEE STD 802.11-2012,第20.3.9.4节中进行了描述。万博1manbetx对HT混合格式的支持是必须的。
PPDU
物理层收敛过程(PLCP)协议数据单元(PPDU)是完整的PLCP框架,包括PLCP标头,MAC标头,MAC数据字段以及MAC和PLCP预告片。
参考
[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 ++代码生成
使用MATLAB®CODER™生成C和C ++代码。
Usage notes and limitations:
Use in aMATLAB功能block is not supported.
在R2015B中引入
[1]IEEE STD 802.11-2012经IEEE许可改编并重印。版权所有2012。保留所有权利。
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