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Permute input symbols by selecting matrix elements along diagonals

Block sublibrary of Interleaving

The Matrix Helical Scan Interleaver block performs block interleaving
by filling a matrix with the input symbols row by row and then sending
the matrix contents to the output port in a helical fashion. The **Number
of rows** and **Number of columns** parameters
are the dimensions of the matrix that the block uses internally for
its computations.

Helical fashion means that the block selects output symbols
by selecting elements along diagonals of the matrix. The number of
elements in each diagonal matches the **Number of columns** parameter,
after the block wraps past the edges of the matrix when necessary.
The block traverses diagonals so that the row index and column index
both increase. Each diagonal after the first one begins one row below
the first element of the previous diagonal.

The **Array step size** parameter is the slope
of each diagonal, that is, the amount by which the row index increases
as the column index increases by one. This parameter must be an integer
between zero and the **Number of rows** parameter.
If the **Array step size** parameter is zero, then
the block does not interleave and the output is the same as the input.

This block accepts a column vector input signal. The number
of elements of the input vector must be the product of **Number
of rows** and **Number of columns**.

The block accepts the following data types: `int8`

, `uint8`

, `int16`

, `uint16`

, `int32`

, `uint32`

, `boolean`

, `single`

, `double`

,
and fixed-point. The output signal inherits its data type from the
input signal.

**Number of rows**The number of rows in the matrix that the block uses for its computations.

**Number of columns**The number of columns in the matrix that the block uses for its computations.

**Array step size**The slope of the diagonals that the block reads.

If the **Number of rows** and **Number
of columns** parameters are 6 and 4, respectively, then the
interleaver uses a 6-by-4 matrix for its internal computations. If
the **Array step size** parameter is 1, then the
diagonals are as shown in the figure below. Positions with the same
color form part of the same diagonal, and diagonals with darker colors
precede those with lighter colors in the output signal.

Given an input signal of `[1:24]'`

, the block
produces an output of

[1; 6; 11; 16; 5; 10; 15; 20; 9; 14; 19; 24; 13; 18; 23;... 4; 17; 22; 3; 8; 21; 2; 7; 12]

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