Package: comm
Filter input signal through MIMO multipath fading channel
The MIMOChannel
System object™ filters an
input signal through a multipleinput multipleoutput (MIMO) multipath
fading channel. This object models both Rayleigh and Rician fading
and employs the Kronecker model for modeling the spatial correlation
between the links.
The fading processing per link is per the Methodology for Simulating Multipath Fading Channels section and assumes the same parameters for all N_{T} × N_{R} links of the MIMO channel. Each link comprises all multipaths for that link.
To filter an input signal using a MIMO multipath fading channel:
Define and set up your MIMO channel object. See Construction.
Call step
to filter the input
signal through a MIMO multipath fading channel according to the properties
of comm.MIMOChannel
. The behavior of step
is
specific to each object in the toolbox.
H = comm.MIMOChannel
creates a multipleinput
multipleoutput (MIMO) frequency selective or frequency flat fading
channel System object, H
. This object filters
a real or complex input signal through the multipath MIMO channel
to obtain the channel impaired signal.
H = comm.MIMOChannel(
creates
a MIMO channel object, Name
,Value
)H
, with the specified
property Name
set to the specified Value
.
You can specify additional namevalue pair arguments in any order
as (Name1
,Value1
,...,NameN
,ValueN
).

Input signal sample rate (hertz) Specify the sample rate of the input signal in hertz as a doubleprecision,
real, positive scalar. The default value of this property is 

Discrete path delay vector (seconds) Specify the delays of the discrete paths in seconds as a doubleprecision,
real, scalar or row vector. The default value of this property is
0. When you set 

Average path gain vector (decibels) Specify the average gains of the discrete paths in decibels
as a doubleprecision, real, scalar or row vector. The default value
of this property is 

Normalize path gains (logical) Set this property to 

Rayleigh or Rician fading Specify the fading distribution of the channel as one of 

Rician Kfactor scalar or vector (linear scale) Specify the Kfactor of a Rician fading channel as a doubleprecision,
real, positive scalar or positive row vector of the same length as If 

Doppler shifts of lineofsight components (hertz) Specify the Doppler shifts for the lineofsight components
of a Rician fading channel in hertz as a doubleprecision, real scalar
or row vector. The default value of this property is


Initial phases of lineofsight components (radians) Specify the initial phases of the lineofsight components of
a Rician fading channel in radians as a double precision, real scalar
or row vector. The default value of this property is


Maximum Doppler shift (hertz) Specify the maximum Doppler shift for all channel paths in hertz
as a double precision, real, nonnegative scalar. The default value
of this property is The Doppler shift applies to all the paths of the channel. When
you set the The 

Doppler spectrum object Specify the Doppler spectrum shape for the path(s) of the channel.
This property accepts a single Doppler spectrum structure returned
from the If you assign a single Doppler spectrum structure to If you assign the
If you assign a row cell array of different Doppler spectrum
structures to Alternatively, you can specify
This object supports C code generation. To generate C code, specify this property to a single Doppler spectrum structure. 

Spatial correlation Set this property to 

Number of transmit antennas Specify the number of transmit antennas as a numeric, real,
positive integer scalar between 

Number of receive antennas Specify the number of receive antennas as a numeric, real,
positive integer scalar between 

Transmit correlation matrix (or 3D array) Specify the spatial correlation of the transmitter as a doubleprecision,
real or complex, 2D matrix or 3D array. The default value of this
property is The first dimension of If the channel is frequency flat, i.e., If the channel is frequency selective, i.e., 

Receive correlation matrix (or 3D array) Specify the spatial correlation of the receiver as a doubleprecision,
real or complex, 2D matrix or 3D array. The default value of this
property is The first dimension of If the channel is frequency flat, i.e., If the channel is frequency selective, i.e., 

Optional transmit and/or receive antenna selection Specify the antenna selection scheme as one of


Normalize channel outputs (logical) Set this property to 

Fading technique used to model the channel Specify how to model the channel as 

Number of sinusoids used to model the fading process Specify the number of sinusoids used to model the channel as
a positive integer scalar. The property applies when the 

Source to control the start time of the fading process Specify the initial time source as either 

Start time of the fading process (s) Specify the time offset of the fading process as a real nonnegative
scalar. This property applies when the 

Source of random number stream Specify the source of random number stream as one of 

Initial seed of mt19937ar random number stream Specify the initial seed of a mt19937ar random number generator
algorithm as a double precision, real, nonnegative integer scalar.
The default value of this property is 

Enable path gain output (logical) Set this property to 

Enable channel visualization Specify the type of channel visualization to display as one
of 

Antenna pair to display Specify the transmitreceive antenna pair to display as a 1by2
row vector, where the first element corresponds to the desired transmit
antenna and the second corresponds to the desired receive antenna.
At this time, only a single pair can be displayed. This property applies
when 

Percentage of samples to display Specify the percentage of samples to display as one of 

Path for Doppler display Specify, as an integer scalar, the path for which the Doppler
spectrum is displayed. The specified path must be an element of {1,
2, ..., N_{p}},
where N_{p} is the number of
discrete paths per link specified in the object. At this time, only
a single path can be displayed. This property applies when 
clone  Create MIMOChannel object with same property
values 
getNumInputs  Number of expected inputs to step method 
getNumOutputs  Number of outputs from step method 
info  Characteristic information about MIMO Channel 
isLocked  Locked status for input attributes and nontunable properties 
release  Allow property value and input characteristics changes 
reset  Reset states of the MIMOChannel object 
step  Filter input signal through MIMO multipath fading channel 
The fading processing per link is per the Methodology for Simulating Multipath Fading Channels section and assumes the same parameters for all N_{T}· N_{R} links of the MIMO channel. Each link comprises all multipaths for that link.
The Kronecker model assumes that the spatial correlations at the transmit and receive sides are separable. Equivalently, the direction of departure (DoD) and directions of arrival (DoA) spectra are assumed to be separable. The full correlation matrix can then be obtained as:
$${R}_{H}=E\left[{R}_{t}\otimes {R}_{r}\right]$$
where:
The ⊗ symbol represents the Kronecker product.
R_{t} represents the correlation matrix at the transmit side, i.e. $${R}_{t}=E\left[{H}^{H}H\right]$$, of size N_{t}byN_{t}.
R_{r} represents the correlation matrix at the receive side, i.e. $${R}_{r}=E\left[H{H}^{H}\right]$$, of size N_{r}byN_{r}.
You can obtain a realization of the MIMO channel matrix as:
$$H={R}_{r}^{\frac{1}{2}}A{R}_{t}^{\frac{1}{2}}$$
where: A is an N_{r}byN_{t} matrix of i.i.d. complex Gaussian variables with zero mean and unit variance.
The following information explains how this object determines the cutoff frequency factor, f_{c} for different Doppler spectrum types:
For any Doppler spectrum type, other than Gaussian
and BiGaussian, f_{c} equals 1
.
For a Gaussian Doppler spectrum type, f_{c} equals
the Doppler spectrum structure NormalizedStandardDeviations
field
value times sqrt(2∙log(2)).
For a BiGaussian Doppler spectrum type:
If the Doppler spectrum structure PowerGains
field
is [0,0]
, then f_{c} equals
the SigmaGaussian2
(SigmaGaussian1
)
property value times sqrt(2∙log(2)).
If the CenterFreqGaussian1
and CenterFreqGaussian2
property
values are both 0
and the SigmaGaussian1
and SigmaGaussian2
property
values are the same, then f_{c} is also equal
to the SigmaGaussian2
property value times sqrt(2∙log(2)).
In all other cases, f_{c} equals 1
.
When the object is in antenna selection mode, it uses the following algorithms to process an input signal:
The random path gains are always generated and keep
evolving for each link, no matter whether the link is being selected
or not. The path gain values for the nonselected links are marked
as NaN
in the path gain output.
The spatial correlation only applies to the selected
transmit and/or receive antennas, and the correlation coefficients
are the corresponding entries in the transmit and/or receive correlation
matrices. In other words, the spatial correlation matrix for the selected
transmit/receive antennas is a submatrix of the TransmitCorrelationMatrix
/ReceiveCorrelationMatrix
property
value.
The input filtering through the path gains only happens to the selected links.
Whenever a link associated with a specific transmitter
transitions from a selected state to a nonselected state, its channel
filter is reset. For example, if the AntennaSelection
property
is set to Tx
and the selected transmit antenna
is changed from 2 to 1, the channel filter corresponding to antenna
2 will be reset.
Channel output normalization happens over the number of selected receive antennas.
[1] Oestges, C., and B. Clerckx. MIMO Wireless Communications: From RealWorld Propagation to SpaceTime Code Design, Academic Press, 2007.
[2] Correira, L. M. Mobile Broadband Multimedia Networks: Techniques, Models and Tools for 4G, Academic Press, 2006.
[3] Kermoal, J. P., L. Schumacher, K. I. Pedersen, P. E. Mogensen, and F. Frederiksen. "A stochastic MIMO radio channel model with experimental validation." IEEE Journal on Selected Areas of Communications. Vol. 20, Number 6, 2002, pp. 1211–1226.
[4] Jeruchim, M., P. Balaban, and K. S. Shanmugan. Simulation of Communication Systems, Second Edition, New York, Kluwer Academic/Plenum, 2000.
[5] Pätzold, Matthias, ChengXiang Wang, and Bjorn Olav Hogstand. "Two New SumofSinusoidsBased Methods for the Efficient Generation of Multiple Uncorrelated Rayleigh Fading Waveforms." IEEE Transactions on Wireless Communications. Vol. 8, Number 6, 2009, pp. 3122–3131.