Propagation Measurements and Propagation Measurements and Models for Wireless Models for Wireless Communication ChannelsCommunication Channels

指導教授：黃文傑 老師指導教授：黃文傑 老師 學　　生：曾凱霖學　　生：曾凱霖 學　　號：學　　號： M9121014M9121014

無線通訊實驗室無線通訊實驗室

OutlineOutline

11 、 、 The Physics of PropagationThe Physics of Propagation22 、 、 Outdoor PropagationOutdoor Propagation33 、 、 Indoor PropagationIndoor Propagation44 、 、 RF Penetration into BuildingRF Penetration into Building55 、 、 ConclusionConclusion

The Physics of PropagationThe Physics of Propagation• Path parametersPath parameters 11 、、 Path Loss-Path Loss- log-distance path modellog-distance path model ：：

log normal shadowinglog normal shadowing ：：

22 、、 Multipath Delay Spread-Multipath Delay Spread-

)/log(10)()( 00 ddndPLdPL

XdPLdPL )()(

Outdoor PropagationOutdoor Propagation

• MacrocellsMacrocells• MicrocellsMicrocells 11 、、 Microcellular Systems-Microcellular Systems- 22 、、 Street Microcells-Street Microcells-

Indoor PropagationIndoor Propagation

• Propagation inside signal-story buildingsPropagation inside signal-story buildings 11 、、 Temporal Fading for fixed and moving Temporal Fading for fixed and moving terminalterminal 22 、、 Multipath delay spread-Multipath delay spread- 33 、、 Path loss-Path loss-• Propagation Between FloorsPropagation Between Floors• Computer-aided Design for in-building proComputer-aided Design for in-building pro

pagation predictionpagation prediction

RF Penetration into BuildingRF Penetration into Building

• Floors & attenuationsFloors & attenuations

• Penetration loss decreases with Penetration loss decreases with increasing frequencyincreasing frequency

ConclusionConclusion

• 3D numerical modeling3D numerical modeling (time delay statistic, coverage,interferen(time delay statistic, coverage,interferen

ce)ce)• Higher data ratesHigher data rates• AOA statistics in different enviromentsAOA statistics in different enviroments

劇終劇終

Effect of mobility in Effect of mobility in communication systemscommunication systems

Effect of mobility in Effect of mobility in communication systems communication systems (cont.)(cont.)

Effect of mobility in Effect of mobility in communication systems communication systems (cont.)(cont.)

Radio PropagationRadio Propagation

• Introduction (1)Introduction (1)– focus on bands around a few G Hzfocus on bands around a few G Hz

• BW is limited in the lower bandsBW is limited in the lower bands

• penetration is very low above these bandspenetration is very low above these bands

– Advantages:Advantages:• 1 W power can penetrate several floors 1 W power can penetrate several floors

in a building and in a building and a few miles outdoora few miles outdoor

• Antenna ~ a few inchesAntenna ~ a few inches

• A few inches of antenna separation can A few inches of antenna separation can provide provide diversity gain.diversity gain.

Introduction(2)Introduction(2)

– 10 ~ 30 G Hz - signals are confined in a room. Can 10 ~ 30 G Hz - signals are confined in a room. Can extend throughout the building by leaky cable antennasextend throughout the building by leaky cable antennas

• 3 design issues3 design issues– signal coverage -- determines the cell size or service signal coverage -- determines the cell size or service

areaarea– max data rate -- determines the network throughputmax data rate -- determines the network throughput– channel fluctuation rate -- determines the timing and channel fluctuation rate -- determines the timing and

phase phase recoverage circuit and the power control recoverage circuit and the power control algorithmalgorithm

Multipath Fading (2)Multipath Fading (2)

• Amplitude and phase fluctuation caused by Amplitude and phase fluctuation caused by attenuation and difference path lengthattenuation and difference path length

• Exact analysis -- solving Maxwell equation with Exact analysis -- solving Maxwell equation with boundary conditionsboundary conditions

• Ray-tracing method -- use geometric optic Ray-tracing method -- use geometric optic approach and treat propagation as rays, can also approach and treat propagation as rays, can also include transmission through walls and diffraction include transmission through walls and diffraction at building edgesat building edges

Example 3 :Example 3 :(2D ray tracing inside a room)(2D ray tracing inside a room)

• Vertically polarized antennaVertically polarized antenna• reflections from the walls dominatereflections from the walls dominate

LOS

LOS + First Order

Example 3Example 3

• Second & higher order reflections contribute very littleSecond & higher order reflections contribute very little• with 4 walls there are 4 first order reflections, 12 second owith 4 walls there are 4 first order reflections, 12 second o

rder reflections 48 third order reflectionsrder reflections 48 third order reflections• Rays arrive with different amplitudes & phasesRays arrive with different amplitudes & phases• ∴∴by central limit theorem, the combined signal is a zero by central limit theorem, the combined signal is a zero

mean Gaussian R.V. mean Gaussian R.V. • The LOS signal adds a non-zero mean to it. The LOS signal adds a non-zero mean to it. • The amplitude of a complex Gaussian variable has a RiciaThe amplitude of a complex Gaussian variable has a Ricia

n distribution n distribution • reduces to Rayleigh distribution for zero mean casereduces to Rayleigh distribution for zero mean case