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Permute input symbols using helical array


The comm.HelicalInterleaver System object™ permutes the symbols in the input signal by placing them in an array in a helical arrangement and then sending rows of the array to the output port. For more information, see Algorithms.

To helically interleave input symbols:

  1. Create the comm.HelicalInterleaver object and set its properties.

  2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?




intrlvr = comm.HelicalInterleaver creates a default helical interleaver System object.

intrlvr = comm.HelicalInterleaver(Name=Value) sets properties using one or more name-value arguments. For example, NumColumns=6 sets the number of columns in the helical array to 6.


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Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects.

Number of columns in the helical array, specified as a positive integer.

Size of each group of input symbols, specified as a positive integer.

Helical array step size, specified as a positive integer. Step size indicates the number of rows of separation between consecutive input groups in their respective columns of the helical array.

Initial conditions of the helical array, specified as a numeric scalar value. This is the initial value stored in the helical array.



intrlvseq = intrlvr(inputseq)

Input Arguments

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Sequence of symbols, specified as a column vector. Input sequence is of size NumColumns × GroupSize.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | logical | fi

Output Arguments

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Interleaved sequence of symbols, returned as a column vector with the same data type and length as the inputseq argument.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | logical | fi

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:


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stepRun System object algorithm
releaseRelease resources and allow changes to System object property values and input characteristics
resetReset internal states of System object


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Create helical interleaver and deinterleaver System objects.

intrlver = comm.HelicalInterleaver(GroupSize=2,NumColumns=3, ...
deintrlvr = comm.HelicalDeinterleaver(GroupSize=2,NumColumns=3, ...

Generate random data. Interleave and then deinterleave the data.

[dataIn,dataOut] = deal([]);
for k = 1:10
    data = randi(7,6,1);
    intData = intrlver(data);
    deIntData = deintrlvr(intData);
    dataIn = cat(1,dataIn,data);
    dataOut = cat(1,dataOut,deIntData);

Determine the delay through the interleaver and deinterleaver pair.

intlvDelay = finddelay(dataIn,dataOut)
intlvDelay = 6

After taking the interleaving delay into account, confirm that the original and deinterleaved data are identical.

ans = logical


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[1] Berlekamp, E. R. and P. Tong. "Improved Interleavers for Algebraic Block Codes." US Patent 4559625, Dec. 17, 1985.

Extended Capabilities

Version History

Introduced in R2012a