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Permute symbols using set of shift registers with specified delays


The comm.ConvolutionalInterleaver System object™ permutes the symbols in the input sequence by using a set of shift registers, each with its own delay value. For information about delays, see Delays of Convolutional Interleaving and Deinterleaving.

To permute symbols using a set of shift registers with specified delays:

  1. Create the comm.ConvolutionalInterleaver 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.ConvolutionalInterleaver creates a default convolutional interleaver System object.


intrlvr = comm.ConvolutionalInterleaver(Name=Value) sets Properties using one or more name-value arguments. For example, NumRegisters=10 specifies 10 internal shift registers.


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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 internal shift registers, specified as a positive integer.

Data Types: double

Number of additional symbols that fit in each successive shift register, specified as a positive integer. The first register holds zero symbols.

Data Types: double

Initial conditions of the shift registers, specified as one of these options.

  • Scalar — All shift registers, except the first one, store the same specified value.

  • Column vector — If the length of the column vector equals the value of the NumRegisters property, then the kth shift register stores the kth element of the specified vector.

You do not need to specify a value for the first shift register, which has zero delay. Because the first shift register has zero delay, the object ignores the first element of this property.

Data Types: double



intrlvseq = intrlvr(inputseq) permutes the input sequence of symbols by using a set of shift registers. The object outputs the interleaved sequence of symbols.

For information about delays, see Delays of Convolutional Interleaving and Deinterleaving.

Input Arguments

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Sequence of symbols, specified as a column vector.

Data Types: numeric | logical | fi

Output Arguments

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Interleaved sequence of symbols, returned as a column vector of the same data type and size as the inputseq input.

Data Types: numeric | 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 a convolutional interleaver System object, specifying the number of shift registers and register length step.

intrlvr = comm.ConvolutionalInterleaver(NumRegisters=2, ...

Create a convolutional deinterleaver System object, specifying the number of shift registers and register length step.

deintrlvr = comm.ConvolutionalDeinterleaver(NumRegisters=2, ...

Generate a random data sequence. Pass the data sequence through the interleaver and then the deinterleaver.

data = (0:20)';
intrlvData = intrlvr(data);
deintrlvData = deintrlvr(intrlvData);

Display the original sequence, interleaved sequence, and restored sequence.

ans = 21×3

     0     0     0
     1     0     0
     2     2     0
     3     0     0
     4     4     0
     5     0     0
     6     6     0
     7     1     1
     8     8     2
     9     3     3

The delay through the interleaver and deinterleaver pair is equal to the product of the NumRegisters and RegisterLengthStep properties.

intrlvDelay = intrlvr.NumRegisters*intrlvr.RegisterLengthStep
intrlvDelay = 6

After accounting for this delay, verify that the original and deinterleaved data are identical.

numSymErrors = symerr(data(1:end-intrlvDelay), ...
numSymErrors = 0

More About

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[1] Clark, George C., and J. Bibb Cain. Error-Correction Coding for Digital Communications. Applications of Communications Theory. New York: Plenum Press, 1981.

[2] Forney, G., D., Jr. "Burst-Correcting Codes for the Classic Bursty Channel." IEEE Transactions on Communications, vol. COM-19, October 1971. 772-781.

[3] Ramsey, J. L. "Realization of Optimum Interleavers." IEEE Transactions on Information Theory, IT-16 (3), May 1970. 338-345.

Extended Capabilities

Version History

Introduced in R2012a