comm.HelicalDeinterleaver

Restore ordering of symbols using helical array

Description

The HelicalDeinterleaver object permutes the symbols in the input signal by placing them in a row-by-row array and then selecting groups helically to send to the output port.

To helically deinterleave input symbols:

Define and set up your helical deinterleaver object. See Construction.
Call step to deinterleave input symbols according to the properties of comm.HelicalDeinterleaver. 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.HelicalDeinterleaver creates a helical deinterleaver System object, H. This object restores the original ordering of a sequence that was interleaved using the helical interleaver System object.

H = comm.HelicalDeinterleaver(Name,Value) creates a helical deinterleaver object, H, with 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

`NumColumns`	Number of columns in helical array Specify the number of columns in the helical array as a positive integer scalar value. The default is `6`.
`GroupSize`	Size of each group of input symbols Specify the size of each group of input symbols as a positive integer scalar value. The default is `4`.
`StepSize`	Helical array step size Specify number of rows of separation between consecutive input groups in their respective columns of the helical array. This property requires a positive integer scalar value. The default is `1`.
`InitialConditions`	Initial conditions of helical array Specify the value that is initially stored in the helical array as a numeric scalar value. The default is `0`.

Methods

step	Restore ordering of symbols using a helical array

Common to All System Objects
`release`	Allow System object property value changes
`reset`	Reset internal states of System object

Examples

collapse all

Helical Interleaving and Deinterleaving

Open Live Script

Create helical interleaver and deinterleaver objects.

interleaver = comm.HelicalInterleaver('GroupSize',2,'NumColumns',3, ...
    'InitialConditions',-1);
deinterleaver = comm.HelicalDeinterleaver('GroupSize',2,'NumColumns',3, ...
    'InitialConditions',-1);

Generate random data. Interleave and then deinterleave the data.

[dataIn,dataOut] = deal([]);

for k = 1:10
    data = randi(7,6,1);
    intData = interleaver(data);
    deIntData = deinterleaver(intData);
    
    dataIn = cat(1,dataIn,data);
    dataOut = cat(1,dataOut,deIntData);
end

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.

isequal(dataIn(1:end-intlvDelay),dataOut(1+intlvDelay:end))

ans = logical
   1

Algorithms

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