OFDM Equalizer
Equalize OFDM modulated signals
 Library:
Communications Toolbox / Equalizers
Description
The OFDM Equalizer block performs frequencydomain equalization to recover OFDM modulated symbols transmitted through a channel.
This icon shows the block with all ports enabled.
Ports
Input
in
— Input signal
3D array  2D array
Input signal, specified as a 3D or 2D array of received OFDM symbols.
If Data format is set to
3D
, the input signal must be specified as an N_{SC}byN_{Symbols}byN_{R} array. N_{SC} represents the number of OFDM subcarriers, N_{Symbols} represents the number of OFDM symbols, and N_{R} represents the number of receive antennas.If Data format is set to
2D
, the input signal must be specified as an N_{RE}byN_{R} array. N_{RE} represents the number of resource elements in an irregular subset of the OFDM subcarrier symbol grid.
Data Types: double
 single
Complex Number Support: Yes
hEst
— Channel estimate
3D array
Channel estimate, specified as a 3D array.
If Data format is set to
3D
, the block expects hEst to be an N_{SC}byN_{T}byN_{R} or an (N_{SC}×N_{Symbols})byN_{T}byN_{R} array.If hEst is an N_{SC}byN_{T}byN_{R} array, all OFDM symbols in the input signal
in
are equalized by the same channel estimate. N_{SC} represents the number of OFDM subcarriers, N_{T} represents the number of transmit antennas, and N_{R} represents the number of receive antennas.If hEst is an (N_{SC}×N_{Symbols})byN_{T}byN_{R} array, each OFDM symbol in the input signal
in
is equalized by the corresponding entry in hEst. N_{Symbols} represents the number of OFDM symbols.
If Data format is set to
2D
, the block expects hEst to be an N_{RE}byN_{T}byN_{R} array. Each OFDM symbol in the input signalin
is equalized by the corresponding entry in hEst. N_{RE} represents the number of resource elements in an irregular subset of the OFDM subcarrier symbol grid.
Data Types: double
 single
Complex Number Support: Yes
noiseVar
— Noise variance
0 (default)  nonnegative scalar
Noise variance estimate for minimum mean squared error (MMSE) equalization, specified as a nonnegative scalar.
Dependencies
The noise variance input port is used only when you set Noise variance
source to Input port
and
Algorithm to Minimum mean
squared error
.
Data Types: double
 single
Output
out
— Equalized symbols
3D array  2D array
Equalized symbols, returned as a 3D or 2D array.
If Data format is set to
3D
, the block returns an N_{SC}byN_{Symbols}byN_{T} array. N_{SC} represents the number of OFDM subcarriers, N_{Symbols} represents the number of OFDM symbols, and N_{T} represents the number of transmit antennas.If Data format is set to
2D
, the block returns an N_{RE}byN_{T} array. N_{RE} represents the number of resource elements in an irregular subset of the OFDM subcarrier symbol grid.
csi
— Soft channel state information
matrix
Soft channel state information, returned as a matrix with
size(csi,1) = size(hEst,1)
and
size(csi,2) = N_{T}
= size(hEst,2)
.
N_{T} represents the number
of transmit antennas.
Dependencies
To enable this output port, select the Output soft channel state information parameter.
Parameters
Data format
— Format of signals
3D
(default)  2D
Format of the signals, specified as 3D
or
2D
.
When this parameter is set to 3D
, OFDM
subcarriers and OFDM symbols use two separate dimensions in the
representation of in and out.
The in input must be an N_{SC}byN_{Symbols}byN_{R} array.
The out output is returned as an N_{SC}byN_{Symbols}byN_{T} array.
When this parameter is set to 2D
, OFDM
subcarriers and OFDM symbols use one combined dimension in the
representation of in and out.
The in input must be an N_{RE}byN_{R} array.
The out output is returned as an N_{RE}byN_{T} array.
N_{SC} represents the number of OFDM subcarriers. N_{Symbols} represents the number of symbols. N_{RE} represents the number of resource elements in an irregular subset of the OFDM subcarrier symbol grid. N_{T} represents the number of transmit antennas. N_{R} represents the number of receive antennas.
Algorithm
— Equalization algorithm
Minimum mean squared
error
(default)  Zeroforcing
Equalization algorithm, specified as Minimum mean squared
error
or Zeroforcing
.
When this parameter is set to
Minimum mean squared error
, the block equalizes using the MMSE algorithm.When this parameter is set to
Zeroforcing
, the block equalizes using the zeroforcing algorithm. When using the zeroforcing algorithm, the noiseVar port value is ignored.
Noise variance source
— Source of noise variance
Input port
(default)  Property
Source of noise variance, specified as one of these values:
Input port
— Specify this value to use the noiseVar input port to specify the noise variance estimate for MMSE equalization.Property
— Specify this value to use the Noise variance parameter to specify the noise variance estimate for MMSE equalization.
Noise variance
— Noise variance
0 (default)  nonnegative scalar
Noise variance estimate for MMSE equalization, specified as a nonnegative scalar.
Dependencies
The noise variance setting is used only when you set Noise variance
source to Property
and
Algorithm to Minimum mean squared
error
.
Data Types: double
 single
Output soft channel state information
— Enable soft channel state information output
off
(default)  on
Select this parameter to enable output port csi containing the soft channel state information.
Simulate using
— Type of simulation to run
Interpreted execution
(default)  Code generation
Type of simulation to run, specified as Interpreted
execution
or Code generation
.
Interpreted execution
— Simulate the model by using the MATLAB^{®} interpreter. This option requires less startup time than theCode generation
option, but the speed of subsequent simulations is slower. In this mode, you can debug the source code of the block.Code generation
— Simulate the model by using generated C code. The first time you run a simulation, Simulink^{®} generates C code for the block. The C code is reused for subsequent simulations unless the model changes. This option requires additional startup time, but the speed of the subsequent simulations is faster thanInterpreted execution
.
Block Characteristics
Data Types 

Multidimensional Signals 

VariableSize Signals 

Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2022b
See Also
Blocks
 OFDM Modulator Baseband  OFDM Demodulator Baseband  Decision Feedback Equalizer  Linear Equalizer  MLSE Equalizer
Functions
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