Documentation

convintrlv

Permute symbols using shift registers

Syntax

intrlved = convintrlv(data,nrows,slope)
[intrlved,state] = convintrlv(data,nrows,slope)
[intrlved,state] = convintrlv(data,nrows,slope,init_state)

Description

intrlved = convintrlv(data,nrows,slope) permutes the elements in data by using a set of nrows internal shift registers. The delay value of the kth shift register is (k-1)*slope, where k = 1, 2, 3,... nrows. Before the function begins to process data, it initializes all shift registers with zeros. If data is a matrix with multiple rows and columns, the function processes the columns independently.

[intrlved,state] = convintrlv(data,nrows,slope) returns a structure that holds the final state of the shift registers. state.value stores any unshifted symbols. state.index is the index of the next register to be shifted.

[intrlved,state] = convintrlv(data,nrows,slope,init_state) initializes the shift registers with the symbols contained in init_state.value and directs the first input symbol to the shift register referenced by init_state.index. The structure init_state is typically the state output from a previous call to this same function, and is unrelated to the corresponding deinterleaver.

Examples

The example below shows that convintrlv is a special case of the more general function muxintrlv. Both functions yield the same numerical results.

x = randi([0 1],100,1); % Original data
nrows = 5; % Use 5 shift registers
slope = 3; % Delays are 0, 3, 6, 9, and 12.
y = convintrlv(x,nrows,slope); % Interleaving using convintrlv.
delay = [0:3:12]; % Another way to express set of delays
y1 = muxintrlv(x,delay); % Interleave using muxintrlv.
isequal(y,y1)

The output below shows that y, obtained using convintrlv, and y1, obtained using muxintrlv, are the same.

ans =

1

Another example using this function is in Effect of Delays on Recovery of Convolutionally Interleaved Data Using MATLAB.

The example on the muxdeintrlv reference page illustrates how to use the state output and init_state input with that function; the process is analogous for this function.

References

 Heegard, Chris, and Stephen B. Wicker, Turbo Coding, Boston, Kluwer Academic Publishers, 1999.