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getTurboIOIndices

Compute output indices for turbo coding

    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.

    example

    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

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    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

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    Block length, specified as a nonnegative integer.

    Data Types: double

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

    Data Types: double

    Number of registers, specified as a positive integer.

    Data Types: double

    Output Arguments

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    Output indices, returned as column vector of positive integers.

    Extended Capabilities

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

    Introduced in R2021a