OSTBC组合

Combine inputs for received signals and channel estimate according to orthogonal space-time block code (OSTBC)

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MIMO

描述

The OSTBC Combiner block combines the input signal (from all of the receive antennas) and the channel estimate signal to extract the soft information of the symbols that were encoded using an OSTBC. The input channel estimate may not be constant during each codeword block transmission and the combining algorithm uses only the estimate for the first symbol period per codeword block. A symbol demodulator or decoder would follow the Combiner block in a MIMO communications system.

The block conducts the combining operation for each symbol independently. The combining algorithm depends on the structure of the OSTBC. For more information, see theOSTBC Combining Algorithms此帮助页的部分。

方面

与OSTBC传输的时间和空间结构域一起，该块支持可选的维度，在该维度上，合并计算是独立的。金宝app可以将此维度视为基于OFDM的应用程序的频域。下图表示OSTBC组合块的输入和输出的受支持的维度。金宝app

下表描述了块的每个变量。

Variable	描述
F	附加尺寸；通常是频率维度。组合计算与该维度无关。
N	发射天线的数量。
M	接收天线的数量。
T	时间域中的输出符号序列长度。
R	代码的符号率。

Note

On the two inputs, T/R is the symbol sequence length in the time domain.

Fcan be any positive integers.Mcan be 1 through 8, indicated by the接收天线的数量范围。Ncan be 2, 3 or 4, indicated by the发射天线的数量范围。时间域长度T/R必须是代码字块长度的倍数（对于Alamouti；对于所有其他OSTBC，4）。为了N= 2, T/R must be a multiple of 2. WhenN> 2，T/R必须是4的倍数。R默认为2个天线。R可以是 $\frac{3}{4}$ or $\frac{1}{2}$ 对于2个以上的天线。

块的支持金宝app维度取决于FandM。为了one receive antenna (M= 1), the received signal input must be a column vector or a full 2–D matrix, depending on the value forF。相应的通道估计输入必须是完整的2-D或3-D矩阵。

多个接收天线(M> 1），接收的信号输入必须是完整的2-D或3-D矩阵，具体取决于F。Correspondingly, the channel estimate input must be a 3-D or 4-D matrix, depending on the value forF。

To understand the block's dimension propagation, refer to the following table.

	输入1（接收信号）	Input 2 (Channel Estimate)	出去put
F = 1 and M = 1	列向量	2-D	列向量
F = 1和M> 1	2-D	3-D	列向量
F> 1和M = 1	2-D	3-D	2-D
F > 1 and M > 1	3-D	4-D	2-D

数据类型

有关每个块端口支持的数据类型的信息，请参见金宝appSupported Data Typetable on this page. The output signal inherits the data type from the inputs. The block supports different fixed-point properties for the two inputs. For ﬁxed-point signals, the output word length and fractional length depend on the block’s mask parameter settings. See Fixed-Point Signals for more information about fixed-point data propagation of this block.

帧

The output inherits the frameness of the received signal input. For either column vector or full 2-D matrix input signal, the input can be either frame-based or sample-based. A 3–D or 4–D matrix input signal must have sample-based input.

OSTBC Combining Algorithms

The OSTBC Combiner block supports five different OSTBC combining computation algorithms. Depending on the selection for速度and发射天线的数量，您可以选择下表中显示的算法之一。

Transmit Antenna	速度	计算算法每个代码字块长度
2	1	$(\begin{matrix} {\hat{s}}_{1} \\ {\hat{s}}_{2} \end{matrix}) = \frac{1}{^{{‖ H ‖}^{2}}} \sum_{j = 1}^{M} (\begin{matrix} h_{1, j}^{} r_{1, j} + h_{2},_{j} r_{2, j}^{} \\ h_{2,}^{}_{j} r_{1, j} - h_{1},_{j} r_{2, j}^{} \end{matrix}) \cdot$
3	1/2	$(\begin{matrix} {\hat{s}}_{1} \\ {\hat{s}}_{2} \end{matrix}) = \frac{1}{^{{‖ H ‖}^{2}}} \sum_{j = 1}^{M} (\begin{matrix} h_{1, j}^{} r_{1, j} + h_{2, j} r_{2, j}^{} + h_{3,}^{}_{j} r_{3, j} \\ h_{2,}^{}_{j} r_{1, j} - h_{1, j} r_{2, j}^{} - h_{3, j} r_{4, j}^{} \end{matrix}) \cdot$
3	3/4	$(\begin{matrix} {\hat{s}}_{1} \\ \begin{array}{l} {\hat{s}}_{2} \\ {\hat{s}}_{3} \end{array} \end{matrix}) = \frac{1}{^{{‖ H ‖}^{2}}} \sum_{j = 1}^{M} (\begin{matrix} h_{1, j}^{} r_{1, j} + h_{2, j} r_{2, j}^{} - h_{3, j} r_{3, j}^{} \\ h_{2,}^{}_{j} r_{1, j} - h_{1, j} r_{2, j}^{} - h_{3, j} r_{4, j}^{} \\ h_{3, j}^{} r_{1, j} + h_{1, j} r_{3, j}^{} + h_{2, j} r_{4, j}^{*} \end{matrix}) \cdot$
4	1/2	$(\begin{matrix} {\hat{s}}_{1} \\ {\hat{s}}_{2} \end{matrix}) = \frac{1}{^{{‖ H ‖}^{2}}} \sum_{j = 1}^{M} (\begin{matrix} h_{1, j}^{} r_{1, j} + h_{2, j} r_{2, j}^{} + h_{3, j}^{}_{3, j} r_{3, j} + h_{4, j} r_{4, j}^{} \\ h_{2,}^{}_{j} r_{1, j} - h_{1, j} r_{2, j}^{} + h_{4, j}^{} r_{3, j} - h_{3, j} r_{4, j}^{} \end{matrix}) \cdot$
4	3/4	$(\begin{matrix} {\hat{s}}_{1} \\ \begin{array}{l} {\hat{s}}_{2} \\ {\hat{s}}_{3} \end{array} \end{matrix}) = \frac{1}{^{{‖ H ‖}^{2}}} \sum_{j = 1}^{M} (\begin{matrix} h_{1, j}^{} r_{1, j} + h_{2, j} r_{2, j}^{} - h_{3, j} r_{3, j}^{} - h_{4}^{}_{, j} r_{4 j} \\ h_{2,}^{}_{j} r_{1 j} - h_{1, j} r_{2, j}^{} + h_{4}^{}_{, j} r_{3, j} - h_{3, j} r_{4, j}^{} \\ h_{3,}^{}_{j} r_{1 j} + h_{4, j}^{}_{} r_{2, j} + h_{1, j} r_{3, j}^{} + h_{2, j} r_{4, j}^{} \end{matrix}) \cdot$

${\hat{s}}_{k}$ represents the estimatedkOSTBC代码字矩阵中的符号。h_IJrepresents the estimate for the channel from theith transmit antenna and thej接收天线。值iandj可以从1到N(the number of transmit antennas) and toM(the number of receive antennas) respectively.r_ljrepresents thelth symbol at thej每个代码字块接收天线。的价值l可以从1到the codeword block length. ${‖ H ‖}^{2}$ represents the summation of channel power per link, i.e., ${‖ H ‖}^{2} = {\sum_{i = 1}^{N} \sum_{j = 1}^{M} ‖ h_{i j} ‖}^{2}$

Fixed-Point Signals

Use the following formula for ${\hat{s}}_{1}$ for Alamouti code with 1 receive antenna to highlight the data types used for fixed-point signals.

${\hat{s}}_{1} = \frac{h_{1, 1,}^{*} r_{1, 1} + h_{2, 1,} r_{2, 1}^{*}}{^{{‖ H ‖}^{2}}} = \frac{h_{1, 1,}^{*} r_{1, 1} + h_{2, 1,} r_{2, 1}^{*}}{^{h_{1, 1} h_{1, 1,}^{*} + h_{2, 1,} h_{2, 1}^{*}}}$

在这个equation, the data types forProduct outputandAccumulator对应于分子中的产品和求和。同样，类型Energy product outputand能量蓄能器对应于分母中的产品和求和。

Signal Flow Diagram for s₁Combining Calculation of Alamouti Code with One Receive Antenna

The following formula shows the data types used within the OSTBC Combiner block for fixed-point signals for more than one receive antenna for Alamouti code, whereMrepresents the number of receive antennas.
${\hat{s}}_{1} = \frac{h_{1, 1,}^{*} r_{1, 1} + h_{2, 1,} r_{2, 1}^{*} + h_{1, 2}^{*} r_{1, 2} + h_{2, 2} r_{2, 2}^{*} + 。。。 + h_{1, M,}^{*} r_{1, M} + h_{2, M} r_{2, M}^{*}}{h_{1, 1} h_{1, 1}^{*} + h_{2, 1} h_{2, 1}^{*} + h_{1, 2} h_{1, 2}^{*} + h_{2, 2} h_{2, 2}^{*} + 。。。 + h_{1, M} h_{1, M}^{*} + h_{2, M,} h_{2, M}^{*}}$

Signal Flow Diagram for Complex Multiply ofa+IBandc+ID

为了Binary point scaling, you cannot specifyWL_pandFL_p。相反，块隐含地确定这些值WL_aandFL_a

The Internal Rule forProduct outputandEnergy product outputare:

When you select通过内部规则继承,内部规则determinesWL_pandFL_p。Therefore,WL_a=WL_p+ 1和FL_a=FL_p
为了Binary point scaling, you specifyWL_aandFL_a。Therefore,WL_p=WL_a–1和FL_a=FL_p。

为了information on how the Internal Rule applies to theAccumulatorand能量蓄能器, seeInherit via Internal Rule。

Parameters

发射天线的数量: 设置发射天线的数量。该块支持2、3或4个金宝app发射天线。此值默认为2。
速度: 设置代码的符号率。您可以指定3/4或1/2。仅当您使用2个以上的传输天线时才会出现此字段。此字段默认为 $\frac{3}{4}$ for more than 2 transmit antennas. For 2 transmit antennas, there is no rate option and the implicit (default) rate defaults to 1.
接收天线的数量: The number of antennas the block uses to receive signal streams. The block supports from 1 to 8 receive antennas. This value defaults to 1.

Rounding mode

为定点计算设置圆形模式。如果无法通过指定的数据类型和缩放来准确表示值，则该块使用圆形模式。发生这种情况时，该值将四舍五入为代表数字。有关更多信息，请参阅Rounding（定点设计师）。

整数溢出饱和

为定点计算设置溢出模式。如果固定点计算结果的幅度不符合存储结果的数据类型和缩放范围，则使用此参数指定要使用的方法。有关更多信息，请参阅精度和范围。

Product Output

Complex product in the numerator for the diversity combining. For more information refer to the Fixed-Point Signals section of this help page.

Accumulator

在分子中的多样性组合中的求和。

定点通信工具箱™块必须保留进一步计算的求和结果，通常允许您指定累加器的数据类型和缩放。总结之前，大多数这样的块施放在累加器数据类型上：

Use theAccumulator—Modeparameter to specify how you would like to designate the accumulator word and fraction lengths:

When you select通过内部规则继承，累加器输出单词和分数长度自动为您计算。参考Inherit via Internal Rule了解更多信息。
When you selectSame as product output，这些特征与产品输出的特征相匹配。
When you selectSame as input，这些特征与第一个输入的特征与块相匹配。
When you selectBinary point scaling，您能够以位输入单词长度和累加器的分数。
When you select斜率和偏见缩放, you are able to enter the word length, in bits, and the slope of the accumulator. The bias of all signals in DSP System Toolbox™ software is zero.

Energy product output

分母中的复杂产物用于计算MIMO通道中的总能量。

能量蓄能器

Summation in the denominator for calculating total energy in the MIMO channel.

分区输出

MIMO通道中总能量结合的归一化多样性。

Supported Data Type

Port	金宝app支持的数据类型
Rx	Double-precision floating point Single-precision floating point Signed Fixed-point
cEst	Double-precision floating point Single-precision floating point Signed Fixed-point
出去	Double-precision floating point Single-precision floating point Signed Fixed-point

例子

为了an example of this block in use, seeOSTBC Over 3x2 Rayleigh Fading Channel。The model shows the use of a rate ¾ OSTBC for 3 transmit and 2 receive antennas with BPSK modulation using independent fading links and AWGN.

您还可以通过键入与TCM示例在串联OSTBC中看到块commtcmastBC在Matlab^®命令行。

Extended Capabilities

C/C ++代码生成
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2009a