Simulation Model for Mobile Radio Channels
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Transcript of Simulation Model for Mobile Radio Channels
Simulation Model for Simulation Model for Mobile Radio Channels Mobile Radio Channels
Ciprian Romeo ComCiprian Romeo ComşaşaIolanda AlecsandrescuIolanda Alecsandrescu
Andrei MaiorescuAndrei MaiorescuIon BogdanIon Bogdan
[email protected]@etc.tuiasi.ro
Technical University “Gh. Asachi” IaTechnical University “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of Telecommunications
22July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 22
Radio channelRadio channel
Diffraction
ReflectionScattering
Radio channel: propagation medium characterized by wave phenomena.
33July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 33
FadingFading
Waves are received on different propagation ways => Multi-path Propagation.The propagation is realized mostly by reflection and diffraction.
The sum of waves received may have significant variations even on slow motion of receiver.This is called short-term fadingshort-term fading or fast fadingfast fading and follows a Rayleigh distribution.
LOS propagation
Diffraction
Reflection
44July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 44
FadingFading
Waves are received on different propagation ways => Multi-path Propagation.The propagation is realized mostly by reflection and diffraction.
The sum of waves received may have significant variations even on slow motion of receiver.This is called short-term fadingshort-term fading or fast fadingfast fading and follows a Rayleigh distribution.
The mean of the received signal has slow variations on larger motion.This is called long-term fadinglong-term fading and follows a log-normal distribution.
Short-term fading
Long-term fading
55July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 55
Channel ModelingChannel Modeling A channel model has to allow the evaluation of the propagation loses and theirs A channel model has to allow the evaluation of the propagation loses and theirs
variations (fading).variations (fading). The Suzuki model takes into account short-term fading with superimposed long-The Suzuki model takes into account short-term fading with superimposed long-
term log-normal variations of the mean of received signal:term log-normal variations of the mean of received signal:
( ) ( ) ( )t t t
66July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 66
Analytical model – Stochastic Analytical model – Stochastic process: process:
( ) ( ) ( )t t t Extended Suzuki Stochastic process Log-normal process
models the short-time fadingmodels the short-time fading is obtained considering:is obtained considering:
complex zero mean Gaussian noise processcomplex zero mean Gaussian noise process
with cross-correlated quadrature components and with cross-correlated quadrature components and LOS component supposed to be independent of time (for short-time fading)LOS component supposed to be independent of time (for short-time fading)
is obtained as envelope of nonzero mean Gaussian noise processis obtained as envelope of nonzero mean Gaussian noise process
For particular values of environment parameters, this process For particular values of environment parameters, this process follows follows RiceRice, , RayleighRayleigh or or one-sided Gaussianone-sided Gaussian distribution. distribution.
1 2( ) ( ) ( )t t j t
2 ( )t1( )t
1 2
jm m j m e
( ) ( )t t m 2 21 1 2 2( ) ( ( ) ) ( ( ) )t t m t m
77July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 77
Analytical model – Log-normal Analytical model – Log-normal process: process:
( ) ( ) ( )t t t Extended Suzuki Log-normal processStochastic process
models the long-time fading, caused by shadowing effectsmodels the long-time fading, caused by shadowing effects
is obtained from another real Gaussian noise process is obtained from another real Gaussian noise process with zero mean and unit variance:with zero mean and unit variance:
m and s are two environment parameters m and s are two environment parameters and are uncorrelatedand are uncorrelated( )t
3( )t
3( )t
3 ( )( ) m s tt e
88July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 88
Simulation ModelSimulation Model
cross-correlatedcross-correlated Simulation coefficients:Simulation coefficients:
-Doppler coefficients-Doppler coefficients -discrete Doppler -discrete Doppler
frequenciesfrequencies - Doppler phases- Doppler phases
= number of = number of sinusoids used to sinusoids used to approximate the Gaussian approximate the Gaussian processesprocesses
1 2( ), ( )t t
,i nc
,i nf
,i n
1 2,N N
99July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 99
SimulationSimulation A mixed signal simulation tool is used – Saber Designer with MAST languageA mixed signal simulation tool is used – Saber Designer with MAST language MAST = HDL => the channel model can be used for simulations deeper to MAST = HDL => the channel model can be used for simulations deeper to
hardware systemshardware systemsSimulation DataSimulation Data
Environment parameters:Environment parameters:
Number of sinusoids: NNumber of sinusoids: N11=25 and N=25 and N22=15.=15.
Number of samples NNumber of samples NSS=10=1088 and sampling period T and sampling period Taa=3=3·10·10-8-8s.s.
Maximum Doppler frequency fMaximum Doppler frequency fmaxmax=91Hz, corresponding to a vehicle’s speed of =91Hz, corresponding to a vehicle’s speed of
110Km/h.110Km/h.
Doppler coefficients cDoppler coefficients ci,ni,n and discrete Doppler frequencies f and discrete Doppler frequencies fi,ni,n are calculated at are calculated at
the beginning and kept constants during the simulation.the beginning and kept constants during the simulation. Doppler phases Doppler phases θθi,ni,n are modified at each simulation step given by sampling are modified at each simulation step given by sampling..
1010July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 1010
Simulation results (1)Simulation results (1)
Envelope of the simulated extended Suzuki processEnvelope of the simulated extended Suzuki process
1111July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 1111
Simulation results (2)Simulation results (2)
The differences between the generated signal distribution obtained as The differences between the generated signal distribution obtained as histogram and the analytical pdf are hardly observable.histogram and the analytical pdf are hardly observable.
The values for mean and standard deviation confirms this affirmationThe values for mean and standard deviation confirms this affirmation..
1212July, 2002July, 2002
TecTechhnical Universitnical University “Gh. Asachi” Iay “Gh. Asachi” IaşşiiDepartment of TelecommunicationsDepartment of TelecommunicationsSlide Slide 1212
ConclusionConclusion
Histogram of simulated extended Suzuki model, in cases of:Histogram of simulated extended Suzuki model, in cases of: Light shadowing Light shadowing log-normal distribution log-normal distribution Heavy shadowing Heavy shadowing Rice (or Rayleigh) distribution Rice (or Rayleigh) distribution