getTurboIOIndices

Compute output indices for turbo coding

Syntax

indices=getTurboIOIndices(blklen,N,mlen)

indices=getTurboIOIndices(blklen,N,mlen,'LTE')

Description

Use getTurboIOIndices to generate the output indices for the comm.TurboEncoder and input indices for the comm.TurboDecoder and System objects.

indices=getTurboIOIndices(blklen,N,mlen) computes the indices for a given input block length, blklen, number of output streams, N, and the memory length, mlen, relative to the fully encoded output. In this mode, the second interleaved, systematic bit-stream is punctured. N and mlen correspond to the constituent coder configuration for the comm.TurboEncoder and comm.TurboDecoder System objects.

indices=getTurboIOIndices(blklen,N,mlen,'LTE') computes LTE-like output indices as specified by TS 36.212. For LTE, the second systematic bit-stream is punctured and the tail bits are reordered.

Examples

Create Output Indices for Turbo Encoder

Create output indices for use with a turbo encoder System Object™.

Initialize input parameters for a constituent turbo encoder configuration having 2 streams, 3 registers and a block length of 64. Create the output indices vector. Display the number of tail bits and the values of the tail bits.

blklen = 64; % Block length
N = 2;       % Number of streams
mlen = 3;    % Number of registers
firsttailbit = blklen * (2*N - 1) + 1;
outindices = getTurboIOIndices(blklen,N,mlen);
numtailbits = length(outindices(firsttailbit:end)')

numtailbits = 9

tailbits = outindices(firsttailbit:end)'

tailbits = 1×9

   257   258   260   261   262   264   265   266   268

For comparison, keep the same input settings for the block length, number of streams, and number of registers, but create a set of LTE-like output indices vector by adding 'LTE' as the fourth input argument.

outindices = getTurboIOIndices(blklen,N,mlen,'LTE');

Display the number of tail bits and the values of the tail bits. The LTE-like output indices have ordering as specified in TS 36.212 and include tail bits for all output streams.

numtailbitsLTE = length(outindices(firsttailbit:end)')

numtailbitsLTE = 12

tailbitsLTE = outindices(firsttailbit:end)'

tailbitsLTE = 1×12

   257   258   261   262   265   266   259   260   263   264   267   268

Input Arguments

blklen — Block length

64 (default) | nonnegative integer

Block length, specified as a nonnegative integer.

Data Types: double

N — Number of output streams

2 (default) | integer greater than 1

Number of output streams, specified as an integer greater than 1.

Data Types: double

mlen — Number of registers

2 (default) | integer

Number of registers, specified as a positive integer.

Data Types: double

Output Arguments

indices — Output indices

column vector

Output indices, returned as column vector of positive integers.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.