Decode input signal using parallel concatenated decoding scheme
The Turbo Decoder
System
object™ decodes
the input signal using a parallel concatenated decoding scheme that
employs the a-posteriori probability (APP) decoder
as the constituent decoder. Both constituent decoders use the same
trellis structure and algorithm.
To decode an input signal using a turbo decoding scheme:
Define and set up your turbo decoder object. See Construction.
Call step
to decode a binary signal
according to the properties of comm.TurboDecoder
.
The behavior of step
is specific to each object in
the toolbox.
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.
creates
a System
object, H
= comm.TurboDecoderH
. This object uses the a-posteriori probability
(APP) constituent decoder to iteratively decode the parallel-concatenated
convolutionally encoded input data.
creates
a turbo decoder object, H
= comm.TurboDecoder(Name
, Value
)H
, with the specified
property name set to the specified value. Name
must
appear inside single quotes (''
). You can specify
several name-value pair arguments in any order as Name1,Value1,…,NameN,ValueN
.
creates a turbo decoder object, H
= comm.TurboDecoder(TRELLIS,
INTERLVRINDICES, NUMITER)H
, with the
TrellisStructure
property set to TRELLIS
,
the InterleaverIndices
property set to INTERLVRINDICES
, and the
NumIterations
property set to
NUMITER
.
|
Trellis structure of constituent convolutional code Specify the trellis as a MATLAB structure that contains the
trellis description of the constituent convolutional code. Use the |
|
Source of interleaver indices Specify the source of the interleaver indices as one of Default: |
|
Interleaver indices Specify the mapping used to permute the input bits at the encoder as a column vector of integers. This mapping is a vector with the number of elements equal to length, L, of the output of the step method. Each element must be an integer between 1 and L, with no repeated values. Default: |
|
Decoding algorithm Specify the decoding algorithm that the object uses for decoding
as one of Default: |
|
Number of scaling bits Specify the number of bits the constituent decoders use to scale the input data to avoid
losing precision during the computations. The constituent decoders multiply
the input by 2 NumScalingBits and divide the
pre-output by the same factor. The Default: |
|
Number of decoding iterations Specify the number of decoding iterations used for each call
to the Default: |
step | Decode input signal using parallel concatenated decoding scheme |
Common to All System Objects | |
---|---|
release | Allow System object property value changes |
This object implements the algorithm, inputs, and outputs described on the Turbo Decoder block reference page. The object properties correspond to the block parameters.