Equalize using maximum likelihood sequence estimation
The MLSEEqualizer
object uses the Viterbi algorithm
to equalize a linearly modulated signal through a dispersive channel.
The object processes input frames and outputs the maximum likelihood
sequence estimate (MLSE) of the signal. This processing uses an estimate
of the channel modeled as a finite impulse response (FIR) filter.
To equalize a linearly modulated signal and output the maximum likelihood sequence estimate:
Define and set up your maximum likelihood sequence estimate equalizer object. See Construction.
Call step
to equalize a linearly
modulated signal and output the maximum likelihood sequence estimate
according to the properties of comm.MLSEEqualizer
.
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.
H = comm.MLSEEqualizer
creates a maximum
likelihood sequence estimation equalizer (MLSEE) System
object, H
.
This object uses the Viterbi algorithm and a channel estimate to equalize
a linearly modulated signal that has been transmitted through a dispersive
channel.
H = comm.MLSEEqualizer(
creates
an MLSEE object, Name
,Value
)H
, with each specified property
set to the specified value. You can specify additional namevalue
pair arguments in any order as (Name1
,Value1
,...,NameN
,ValueN
).
H = comm.MLSEEqualizer(CHANNEL,
creates
an MLSEE object, Name
,Value
)H
. This object has the Channel
property
set to CHANNEL
, and the other specified properties
set to the specified values.

Source of channel coefficients Specify the source of the channel coefficients as one of 

Channel coefficients Specify the channel as a numeric, column vector containing the coefficients of an FIR filter.
The default is 

Input signal constellation Specify the constellation of the input modulated signal as a
complex vector. The default is 

Traceback depth of Viterbi algorithm Specify the number of trellis branches (the number of symbols), the Viterbi algorithm uses to
construct each traceback path. The default is 

Termination method of Viterbi algorithm Specify the termination method of the Viterbi algorithm as one of


Enable equalizer reset input Set this property to 

Source of preamble Specify the source of the preamble that is expected to precede the input signal. Choose from


Preamble that precedes input signals Specify a preamble that is expected to precede the data in the input signal as an integer, row
vector. The default is 

Source of postamble Specify the source of the postamble that is expected to follow the input signal. Choose from


Postamble that follows input signals Specify a postamble that is expected to follow the data in the input signal as an integer row
vector. The default is 

Number of samples per symbol Specify the number of samples per symbol in the input signal
as an integer scalar value. The default is 
reset  Reset states of MLSEE object 
step  Equalize using maximum likelihood sequence estimation 
Common to All System Objects  

clone  Create System object with same property values 
getNumInputs  Expected number of inputs to a System object 
getNumOutputs  Expected number of outputs of a System object 
isLocked  Check locked states of a System object (logical) 
release  Allow System object property value changes 
This object implements the algorithm, inputs, and outputs described on the MLSE Equalizer block reference page. The object properties correspond to the block parameters.