Radio Propagation Models

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Mahasiswa dapat membuat estimasi disain radio link,dapat menghitung link budget antar BTS sertamenghitung link budget antara BTS dengan user

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Field strength vs Distance

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Type of cell

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Macro cells'yBase stations at high-points

yCoverage of several kilometers

yThe average path loss at a distance d (in dB)has normal distributionyAvg path loss is result of many forward scattering

over a great many of obstacles

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Macro cells'yOkumura did comprehensive measurements

in 1968 and came up with a model.

y Discovered that a good model for path loss was asimple power law where the exponent is afunction of frequency and antenna heights.

y

Valid for frequencies in: 100MHz 1920 MHzfor distances: 1km 100km

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Okumara-HataModel

y fc: the frequency in MHz

y hb: effective transmitter antenna height in meters (30-200m)y hm: effective receiver antenna height in meters (1-10m)

y d : base station mobile separation in kilometers.

y a(hm) is the correction factor for effective mobile antennaheight

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the correction factor a(hm)

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MicrocellsyPropagation differs significantly

y

Milder propagation characteristicsySmall multipath delay spread and shallow

fading imply the feasibility of higher data-rate transmission

yMostly used in crowded urban areas

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Macrocells versusMicrocells

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StreetMicrocellsy Most of the signal power propagates along the

street.

y The signals may reach with LOS paths if thereceiver is along the same street with thetransmitter

y The signals may reach via indirect propagationmechanisms if the receiver turns to another street

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StreetMicrocells

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Indoor Propagationy Indoor channels are different from traditional mobile

radio channels in two different ways:

y

The distances covered are much smallery The variability of the environment is much greater for a

much smaller range of T-R separation distances.

y The propagation inside a building is influenced by:

y Layout of the buildingy Construction materials

y Building type: sports arena, residential home, factory,...

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y Indoor propagation is dominated by the samemechanisms as outdoor: reflection, scattering,diffraction.y However, conditions are much more variable

y Doors/windows open or not

y The mounting place of antenna: desk, ceiling, etc.

y The level of f loors

Indoor channels are classified asy Indoor channels are classified as

y Line-of-sight (LOS)

y Obstructed (OBS) with varying degrees of clutter

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Indoor Propagationy Building types

y Residential homes in suburban areas

y

Residential homes in urban areasy Traditional office buildings with fixed walls (hard

partitions)

y Open plan buildings with movable wall panels (softpartitions)

y Factory buildingsy Grocery stores

y Retail stores

y Sport arenas

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Indoor propagation events and

parametersy Temporal fading for fixed and moving terminals

y Motion of people inside building causes Ricean Fading for thestationary receivers

y Portable receivers experience in general:y Rayleigh fading for OBS propagation paths

y Ricean fading for LOS paths.

y Multipath Delay Spready Buildings with fewer metals and hard-partitions typically have small

rms delay spreads: 30-60ns.y Can support data rates exceding of several Mbps without equalization

y Larger buildings with great amount of metal and open aisles mayhave rms delay spreads as large as 300ns.y Can not support data rates more than a few hundred Kbps without

equalization.

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Path LossModels for Picocells and

Indoory Range: 30m 100m

yMulti-floor Attenuation Model

y n: number of floors through which signals are passing

y F: signal attenuation provided by each floor

y d: distance between transmitter and receiver (m)

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Path LossModels Using Building

Materialy The Partition-dependent Model

y mtype: number of partitions of that type

y Wtype : the path loss in dB attributed to such a partition

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Femto-cellular Areas

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Model Prediksi Redaman COST231

y EURO_COST (the European Co_operative for Scientificand Technical Research) untuk PCS. sampai 2 GHz.

y Tower BTS dengan antena yang telah dirancang untuk

bekerja pada frekuensi GSM : underlay,y Pengembangannya perlu penambahan kapasitas.

ditambahkan antena dengan frekuensi yang bekerja padadaerah PCS : overlay