Modeling of Terrestrial Modeling of Terrestrial Channels in System CChannels in System C

Copyright, 1996 © Dale Carnegie & Associates, Inc.

by Jiangtao YiPhilips Research Lab

IntroductionIntroduction

The first step in Multi_Standard Channel Decoder project is to build a system specification at several level of abstraction in System C. Channel Modeling is part of this work.

MSCD: SpecificationMSCD: Specification

•System Spec.

• Hardware Architecture Spec.

• Hardware Design Spec.

• IC: MSCD

My ScopeMy Scope

Channel Tx

• Simulation (System Spec.)

Rx ADC

Top level Requirement for ChannelTop level Requirement for Channel

• AWGNAWGN

• MultipathMultipath• RayleighRayleigh

• RiceRice

• DopplerDoppler

• Inter-channel interferenceInter-channel interference

• Phase noisePhase noise

Software ArchitectureSoftware Architecture

Multipath fading

Parameter Selector

AWGN Tx

ADC

Rx

• System C

Advantages using System C Advantages using System C ModuleModule

• Scalable and Flexible.Scalable and Flexible.

• Can be simulated with different Tx/Rx.Can be simulated with different Tx/Rx.

• Build-in Analysis can be provided.Build-in Analysis can be provided.

• User Extensible.User Extensible.

Impulse Response Model of Impulse Response Model of Multi-path Channel Multi-path Channel

Baseband ModelBaseband Model

hb(t, ) c(t) r(t)

• x(t) = Re{c(t)exp(jct)}

• y(t) = Re{r(t)exp(jct)}

BandPass ModelBandPass Model

h(t, ) = 2*Re {hb(t,)exp(jct)}

x(t)

y(t)

• In Multi-path Channel

h(t, ) = k {hbk(t, ) exp(jct)}

hbk(t, ) = Ak(t, ) (t- k(t)) exp(j*k)

• k is phase shift for each path

• Ak (t, ) is Rayleigh&Doppler

fading factor (complex)

Bandpass Model for One PathBandpass Model for One Path

x(t)

A(t)

delay

exp(jc k +j k))

Re{ }

y(t) x(t- k)

• y(t) = conv(x(t), Re{hk(t)})

= x(t- k) * Re{ A(t) exp (j(c k +k))}

Rayleigh Fading(Baseband)Rayleigh Fading(Baseband)

Gaussian Spec

Doppler filter

IFFT

Gaussian Spec

Doppler filter

IFFT *j

interpolating

A(t)

• Clarks Model

Interpolating filterInterpolating filter

• Cubic Spline interpolating side band 50 dB down

• linear interpolating side band 20 dB down

Channel TestingChannel Testing

• This Model is tested with a model of US DTV transimitter(8-VSB).

• Wc = 1.31 M Hz.

• Fs = 21.52 M Hz.

• Doppler_sampling_rate = 215.2 Hz

Ensemble PRBAEnsemble PRBA• Fading Attenu Delay Doppler shift

• 1 Rayleigh -20(dB) -1.8(us)0.05(Hz)

• 2 Static 0 0 0

• 3 Rayleigh -20 0.15 0.05

• 4 Rayleigh -10 1.8 0.5

• 5 Rayleigh -14 5.7 2

• 6 Rayleigh -18 18 5

• Default Phase = 0

Indoor Channel Model Study For Antenna Diversity Reception

Xuemei Ouyang

Ensemble PRBFEnsemble PRBF

• Fading Attenu Delay Doppler shift

• 1 Rayleigh -18(dB) -1.8(us)0.05(Hz)

• 2 Static 0 0 0

• 3 Rayleigh -3 0.0465 0.05

• Default Phase = 0

Indoor Channel Model Study For Antenna Diversity Reception

Xuemei Ouyang

Harbor ChannelHarbor Channel

• Fading Attenu Delay phase Doppler shift

• 1 Static -3(dB) 1.2546(us) 0 0(Hz)

• 2 Static -18 1.4405 0 0

• 3 Static -8 3.0204 180 0

• 4 Static -11.6 3.4387 0 0

• 5 Static -17 6.0409 180 0

• 6 Static -26 7.5743 0 0

• 7 Static -20 9.8513 180 0

(take the coefficiency > -40 dB)

AWGN SNR = 20AWGN SNR = 20

• In band power density = 10 dB

• Average power density = 7 dB

• Noise = -13 dB

• SNR = 20 dB

QuantizationQuantization

• Quant Error = - 75dB

• Full Range = ± 16 = 21dB

• -96 dB 16 bit Accuracy

SummarySummary

• The terrestrial channel model is done on Rayleigh fading path, AWGN, and fixed 16 bit Quantizor.

• Further work lies in Lognormal fading path, configurable quantizor and tunner; also more ensemble need to be tested.