Filter signal through 802.11n multipath fading channel
The wlanTGnChannel
System
object™ filters
an input signal through an 802.11n™ (TGn) multipath fading channel.
The fading processing assumes the same parameters for all N_{T}byN_{R} links of the TGn channel. N_{T} is the number of transmit antennas and N_{R} is the number of receive antennas. Each link comprises all multipaths for that link.
To filter an input signal using a TGn multipath fading channel:
Define and set up your TGn channel object. See Construction.
Call step
to filter the input signal through a
TGn multipath fading channel according to the properties of wlanTGnChannel
.
Alternatively, 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.
tgn = wlanTGnChannel
creates a TGn fading
channel System
object, tgn
. This object filters
a real or complex input signal through the TGn channel to obtain the
channelimpaired signal.
tgn = wlanTGnChannel(
creates
a TGn channel object, Name
,Value
)tgn
, 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 (Hz) Sample rate of the input signal in Hz, specified as a real positive
scalar. The default is  

Delay profile model Delay profile model, specified as
 

RF carrier frequency (Hz) Carrier frequency of the channel in Hz, specified as a real
positive scalar. The default is  

Normalize path gains To normalize the fading processes such that the total power
of the path gains, averaged over time, is 0 dB, set this property
to  

Number of transmit antennas Number of transmit antennas, specified as a positive integer
scalar from  

Distance between transmit antenna elements Distance between transmit antenna elements, specified as a real
positive scalar expressed in wavelengths. The default is  

Number of receive antennas Number of receive antennas, specified as a positive integer
scalar from  

Distance between receive antenna elements Distance between receive antenna elements, specified as a real
positive scalar expressed in wavelengths. The default is  

Large scale fading effects Type of largescale fading effects, specified as  

Distance between the transmitter and receiver (m) Distance in meters between the transmitter and receiver, specified
as a real positive scalar. The default is  

Enable fluorescent effect To include Doppler effects due to fluorescent lighting, set
this property to  

Frequency of the power line (Hz) Frequency of the power line in Hz, specified as either  

Normalize channel outputs To normalize the channel outputs by the number of receive antennas,
set this property to  

Source of random number stream Source of random number stream, specified as If you set If you set  

Initial seed of mt19937ar random number stream Initial seed of an mt19937ar random number generator algorithm,
specified as a real, nonnegative integer scalar. The default is  

Enable path gain output To enable computation of path gain output, set this property
to 
info  Characteristic information about TGn Channel 
reset  Reset states of the wlanTGnChannel object 
step  Filter signal through 802.11n multipath fading channel 
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 
The 802.11n channel object uses a filtered Gaussian noise model in which the path delays, powers, angular spread, angles of arrival, and angles of departure are determined empirically. The specific modeling approach is described in [1].
The channel is modeled as several clusters each of which represents an independent propagation path between the transmitter and the receiver. A cluster is composed of subpaths or taps which share angular spreads, angles of arrival, and angles of departure. Delay and power level vary from tap to tap. Within the TGn model, clusters comprise 1–7 taps. The cluster parameters for cluster 1 of Model B are shown in the table.
Parameter  Tap  

1  2  3  4  5  
Delay (ns)  0  10  20  30  40 
Power (dB)  0  –5.4  –10.8  –16.2  –21.7 
Angle of arrival (°)  4.3  4.3  4.3  4.3  4.3 
Receiver angular spread (°)  14.4  14.4  14.4  14.4  14.4 
Angle of departure (°)  225.1  225.1  225.1  225.1  225.1 
Transmitter angular spread (°)  14.4  14.4  14.4  14.4  14.4 
For each model, the first tap has a lineofsight (LOS) between the transmitter and receiver, whereas all other taps are nonlineofsight (NLOS). As a result, the first tap exhibits Rician behavior, while the others exhibit Rayleigh behavior. The Rician Kfactor is the ratio between the power in the first tap and the power in the other taps. A large Kfactor indicates a strong, LOS component.
The angles of arrival and departure for each cluster are randomly selected from a uniform distribution over [0, 2π]. These angles are independent of each other and are fixed for all channel realizations. By fixing the values, the transmit and receive correlation matrices are computed only once. Angular spread values were indirectly determined from empirical data and fall within the 20° to 40° range.
The path loss exponent and the standard deviation of the shadow fading loss characterize each model. The two parameters are depend on the presence of a lineofsight between the transmitter and receiver. For paths with a transmittertoreceiver distance, d, less that the breakpoint distance, d_{BP}, the LOS parameters apply. For d >d_{BP}, the NLOS parameters apply. The table summarizes the path loss and shadow fading parameters.
Parameter  Model  

A  B  C  D  E  F  
Breakpoint distance, d_{BP} (m)  5  5  5  10  20  30 
Path loss exponent for d ≤ d_{BP}  2  2  2  2  2  2 
Path loss exponent for d >d_{BP}  3.5  3.5  3.5  3.5  3.5  3.5 
Shadow fading σ (dB) for d ≤ d_{BP}  3  3  3  3  3  3 
Shadow fading σ (dB) for d >d_{BP}  4  4  5  5  6  6 
In indoor environments, the transmitter and receiver are stationary, and Doppler effects arise from people moving between them. The TGn model employs a bellshaped Doppler spectrum in which the environmental speed, ν_{0}, is 1.2 km/hr. The Doppler spread, f_{d}, is calculated as f_{d} = ν_{0}/λ, where λ is the carrier wavelength.
In addition to basic Doppler effects resulting from environmental
motion, fluorescent lights introduce signal fading at twice the power
line frequency. The effects show up as frequencyselective amplitude
modulation. The effect is included in models D and E. To disable this
effect, set the FluorescentEffects
property to false
.
[1] Erceg, V., L. Schumacher, P. Kyritsi, et al. TGn Channel Models. Version 4. IEEE 802.1103/940r4, May 2004.
[2] 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 in Communications., Vol. 20, No. 6, August 2002, pp. 1211–1226.