For macrocell

Outdoor Propagation Model1

Okumura Model

wholly based on measured data - no analytical explanation

among the simplest & best for in terms of path loss accuracy in cluttered mobile environment

disadvantage: slow response to rapid terrain changes common std deviations between predicted & measured

path loss 10dB - 14dB widely used for urban areas useful for

frequencies ranging from 150MHz-1920MHz frequencies can be extrapolated to 3GHz distances from 1km to 100km base station antenna heights from 30m-1000m

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Okumura developed a set of curves in urban areas with quasi-smooth terrain

effective antenna height: base station hte = 200m mobile: hre = 3m

gives median attenuation relative to free space (Amu)

developed from extensive measurements using

vertical omni- directional antennas at base and mobile

measurements plotted against frequency

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Okumura Model

Estimating path loss using Okumura Model

1. determine free space loss LF , between points of interest

2. add Amu(f,d) and correction factors to account for terrain

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L50(dB)= LF + Amu(f,d) – G(hte) – G(hre) – GAREA

L50 = 50% value of propagation path loss (median)

LF = free space propagation loss

Amu(f,d) = median attenuation relative to free space

G(hte) = base station antenna height gain factor

G(hre) = mobile antenna height gain factor

GAREA = gain due to environment

Four steps: a) calculate free-space path loss at the

considered distance and carrier frequency b) add median attenuation at the considered

distance and carrier frequency c) subtract the TX and RX antenna gains (see

following formulas) d) subtract the gain due to the specific

environment.The values of Aμ(fc, d) and GAREA are obtained fromOkumura empirical plots

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Estimating path loss using Okumura Model

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G(hte) =

200log20 teh

10m < hte < 1000m

G(hre) =

3log10 reh hre 3m

G(hre) =3

log20 reh 3m < hre <10m

model corrected for - h = terrain undulation height - isolated ridge height - average terrain slope - mixed land/sea parameter

Estimating path loss using Okumura Model

Okumura-Hata model cont.

3 types of prediction area : Open area : open space, no tall trees or

building in path Suburban area : Village Highway scattered

with trees and house. Some obstacles near the mobile but not very congested

Urban area : Built up city or large town with large building and houses. Village with close houses and tall

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Median Attenuation Relative to Free Space = Amu(f,d) (dB)

Correction Factor = GAREA(dB)

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Hata Model

empirical model of graphical path loss data from Okumura

predicts median path loss for different channels valid over UHF/VHF band from 150MHz-1.5GHz charts used to characterize factors affecting mobile land

propagation standard formulas for approximating urban propagation loss correction factors for some situations compares closely with Okumura model as d > 1km large

mobile systems incorporates the graphical information from Okumura model

and develops it further to realize the effects of diffraction, reflection and scattering caused by city structures

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Hata Model cont…11

Parameter CommentL50 50th % value (median) propagation path loss (urban)fc frequency from 150MHz-1.5GHz

hte, hre Base Station (30-200m) and Mobile antenna height (1-10m) (hre) correction factor for hre , affected by coverage area

d Tx-Rx separation (1-20km)

L50 (urban)(dB) = 69.55 + 26.16log10 fc – 13.82 log10 the– (hre)

+ (44.9-6.55hte)log10 d

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Mobile Antenna Height Correction Factor for Hata Model

(hre) Comment

(1.1log10 fc - 0.7)hre – (1.56log10 fc - 0.8)dB Medium City

8.29(log10 1.54hre)2 – 1.1 dB Large City (fc 300MHz)

3.2(log10 11.75hre)2 – 4.97 dB Large City (fc > 300MHz)

L50 (dB) Comment

L50 (urban) - 2[log10 (fc/28)]2 – 5.4 Suburban Area

L50 (urban) - 4.78(log10 fc)2 - 18.33log10 fc - 40.98 Rural Area

Hata Model for Rural and Suburban Regions

represent reductions in fixed losses for less demanding environments

PCS Extension to Hata Model

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L50 (urban)(dB) = 46.3 + 33.9logfc – 13.82 loghte

– (hre) + (44.9-6.55hte)logd + CM

CM = 0dB for medium sized cities CM = 3dB metropolitan centers

fc = frequency from 1500MHz - 2

GHz

hte = 30m-200m

hre = 1m-10m

d = 1km-20km

extend Hata model to 2GHz

Example 5

Suppose you received a license to operate at frequency of 1.7 GHz transmitting 5W into a 10dB gain antenna at a height of 30m above the ground. Your portable receiver having an antenna gain of 2dB and height of 1m above the ground level. The portable receiver can be used at a distance of 5km from base station. With this information and using charts from Okumura model estimate the received signal at portable receiver for urban, suburban and open area.

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Example 6

Find the median path loss using Okumura’s model for d =50 km, hte=100m, hre=10m in a suburban environment. If the base station transmitter radiates an EIRP of 1kW at a carrier frequency of 900MHz, find the power at the receiver(assume a unity gain receiving antenna).

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