comm.ConvolutionalInterleaver

Permute input symbols using shift registers with same property values

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Description

The ConvolutionalInterleaver object permutes the symbols in the input signal. Internally, this class uses a set of shift registers.

To convolutionally interleave binary data:

  1. Define and set up your convolutional interleaver object. See Construction.

  2. Call step to convolutionally interleave according to the properties of comm.ConvolutionalInterleaver. The behavior of step is specific to each object in the toolbox.

Note

Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Construction

H = comm.ConvolutionalInterleaver creates a convolutional interleaver System object, H, that permutes the symbols in the input signal using a set of shift registers.

H = comm.ConvolutionalInterleaver(Name,Value) creates a convolutional interleaver System object, H. This object has each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

Properties

NumRegisters

Number of internal shift registers

Specify the number of internal shift registers as a scalar, positive integer. The default is 6.

RegisterLengthStep

Number of additional symbols that fit in each successive shift register

Specify the number of additional symbols that fit in each successive shift register as a positive, scalar integer. The default is 2. The first register holds zero symbols.

InitialConditions

Initial conditions of shift registers

Specify the values that are initially stored in each shift register as a numeric scalar or vector. You do not need to specify a value for the first shift register, which has zero delay. The default is 0. The value of the first element of this property is unimportant because the first shift register has zero delay. If you set this property to a scalar, then all shift registers, except the first one, store the same specified value. If you set it to a column vector with length equal to the value of the NumRegisters property, then the i-th shift register stores the i-th element of the specified vector.

Methods

resetReset states of the convolutional interleaver object
stepPermute input symbols using shift registers
Common to All System Objects
release

Allow System object property value changes

Examples

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Open Live Script

Create convolutional interleaver and deinterleaver objects.

interleaver = comm.ConvolutionalInterleaver('NumRegisters',2, ...
    'RegisterLengthStep',3);
deinterleaver = comm.ConvolutionalDeinterleaver('NumRegisters',2, ...
    'RegisterLengthStep',3);

Generate data, and pass the data through the convolutional interleaver. Pass the interleaved data through the convolutional deinterleaver.

data = (0:20)';
intrlvData = interleaver(data);
deintrlvData = deinterleaver(intrlvData);

Display the original sequence, interleaved sequence and restored sequence.

[data intrlvData deintrlvData]
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. After accounting for this delay, confirm that the original and deinterleaved data are identical.

intrlvDelay = interleaver.NumRegisters * interleaver.RegisterLengthStep
intrlvDelay = 6

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

Algorithms

This object implements the algorithm, inputs, and outputs described on the Convolutional Interleaver block reference page. The object properties correspond to the block parameters.

Extended Capabilities

See Also

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Introduced in R2012a

Communications Toolbox Documentation
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