Question

what is convultional and block interleaving? how Tod demonstrate both in matlab?!

Answer 1

A convolutional interleaver consists of a set of shift registers, each with a fixed delay. In a typical convolutional interleaver, the delays are nonnegative integer multiples of a fixed integer (although a general multiplexed interleaver allows unrestricted delay values). Each new symbol from an input vector feeds into the next shift register and the oldest symbol in that register becomes part of the output vector. A convolutional interleaver has memory; that is, its operation depends not only on current symbols but also on previous symbols.

x = [1:10]'; % Original data
delay = [0; 1; 2]; % Set delays of three shift registers.
hInt = comm.MultiplexedInterleaver('Delay', delay);

y = step(hInt,x) % Interleave.

In this example, the muxintrlv function initializes the three shift registers to the values [], [0], and [0 0], respectively. Then the function processes the input data [1:10]', performing internal computations as indicated in the table below.

y =

     1
     0
     0
     4
     2
     0
     7
     5
     3
    10

block interleaver accepts a set of symbols and rearranges them, without repeating or omitting any of the symbols in the set. The number of symbols in each set is fixed for a given interleaver. The interleaver's operation on a set of symbols is independent of its operation on all other sets of symbols.An interleaver permutes symbols according to a mapping. A corresponding deinterleaver uses the inverse mapping to restore the original sequence of symbols. Interleaving and deinterleaving can be useful for reducing errors caused by burst errors in a communication system.

For example, if the interleaver uses a 2-by-3 matrix to do its internal computations, then for an input of [1 2 3 4 5 6], the block produces an output of [1 4 2 5 3 6].