WIRELESS COMMUNICATION. SYSTEMModul 2 Large Scale Fading
Faculty of Electrical CommunicationIT Telkom
2012Modul 2 Large Scale Fading
Subject
a. Path Loss Modelb. Model Okumura-Hatta, COST 231c. Model Walfish Ikegami, LEE
a. Path Loss Modelb. Model Okumura-Hatta, COST 231c. Model Walfish Ikegami, LEE
Modul 2 Large Scale Fading
IntroductionIn general, the received signal at the receiver point is the sum of thedirect signal and the number of signals reflected from various objects. Inmobile communications, reflection will be caused by:
• Environment• Buildings• Moving object, for example vehicles
Variation of the magnitude and phase of wave reflectiondepends on the reflection coefficient, the trajectory, and alsodepending on the angle of arrival. Thus, differences in the directsignal and reflected signal is:
Modul 2 Large Scale Fading
Variation of the magnitude and phase of wave reflectiondepends on the reflection coefficient, the trajectory, and alsodepending on the angle of arrival. Thus, differences in the directsignal and reflected signal is:
• Amplitude, depending on the magnitude of wave reflectioncoefficient
• Phase, depending on the phase variation of wave reflectionand path distance difference between the direct wave andreflecting wave
The worst condition occurs when the direct wave and reflection wavehas the same magnitude and different phases 180o. In such conditions, thedirect wave and its reflection will eliminate each other (completecancellation )
Wireless Propagation Radio
Free Space LossDiasumsikan terdapat satu sinyal langsung (line of sight path)sangat mudah memprediksi dengan free space formula
ReflectionTerdapat sinyal tak langsung datang ke receiver setelahmengalami pantulan terhadap object. Mungkin terdapat banyakpantulan yang berkontribusi terhadap besarnya delay.
DiffractionPropagasi melewati object yang cukup besar seolah-olahmenghasilkan sumber sekunder, seperti puncak bukit dsb.
ScatteringPropagasi melewati object yang kecil dan/atau kasar yangmenyebabkan banyak pantulan untuk arah-arah yang berbeda.
Free Space LossDiasumsikan terdapat satu sinyal langsung (line of sight path)sangat mudah memprediksi dengan free space formula
ReflectionTerdapat sinyal tak langsung datang ke receiver setelahmengalami pantulan terhadap object. Mungkin terdapat banyakpantulan yang berkontribusi terhadap besarnya delay.
DiffractionPropagasi melewati object yang cukup besar seolah-olahmenghasilkan sumber sekunder, seperti puncak bukit dsb.
ScatteringPropagasi melewati object yang kecil dan/atau kasar yangmenyebabkan banyak pantulan untuk arah-arah yang berbeda.Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Radio Propagation Mechanisms
R
S
transmitterStreet
Building Blocks
D
S
R: ReflectionD: DiffractionS: Scattering
receiver
D
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Efek propagasi multipath pada kanal wirelessmobile adalah:– Large scale fading Large scale path loss– Small scale propagation
Large scale path loss– Large attenuation dalam rata-rata– Daya sinyal terima menurun berbanding terbalik dengan
pangkat- terhadap jarak , dimana umumnya 2 < < 5(untuk komunikasi bergerak). disebut Mean PathlossExponent
– Sebagai dasar untuk metoda prediksi pathloss Small scale
– Flukstuasi sinyal yang cepat disekitar nilai rata-rata(large scale) - nya
– Doppler spread berhubungan dengan kecepatan fading(fading rate)
– Penyebaran waktu berhubungan dengan perbedaan delaywaktu kedatangan masing-masing sinyal multipath.
Efek propagasi multipath pada kanal wirelessmobile adalah:– Large scale fading Large scale path loss– Small scale propagation
Large scale path loss– Large attenuation dalam rata-rata– Daya sinyal terima menurun berbanding terbalik dengan
pangkat- terhadap jarak , dimana umumnya 2 < < 5(untuk komunikasi bergerak). disebut Mean PathlossExponent
– Sebagai dasar untuk metoda prediksi pathloss Small scale
– Flukstuasi sinyal yang cepat disekitar nilai rata-rata(large scale) - nya
– Doppler spread berhubungan dengan kecepatan fading(fading rate)
– Penyebaran waktu berhubungan dengan perbedaan delaywaktu kedatangan masing-masing sinyal multipath.
Modul 2 Large Scale Fading
• Fading didefinisikansebagai fluktuasi daya dipenerima
• Karena perilaku sinyalpada kanal multipathadalah acak, makaanalisis fadingmenggunakan analisisprobabilitas stokastik
• Fading terjadi karenainterferensi atausuperposisi gelombangmultipath yang memilikiamplitudo dan fasa yangberbeda-beda
Definisi Fading
Fading
Large Scale Fading
Small Scale Fading
TerdistribusiLognormal
Terdistribusi Rayleigh / Rician
• Fading didefinisikansebagai fluktuasi daya dipenerima
• Karena perilaku sinyalpada kanal multipathadalah acak, makaanalisis fadingmenggunakan analisisprobabilitas stokastik
• Fading terjadi karenainterferensi atausuperposisi gelombangmultipath yang memilikiamplitudo dan fasa yangberbeda-beda
Modul 2 Large Scale Fading
Definisi : local mean ( time averaged) dari variasi sinyal
Large Scale Fading disebabkankarena akibat keberadaan obyek-obyek pemantul serta penghalangpada kanal propagasi sertapengaruh kontur bumi,menghasilkan perubahan sinyaldalam hal energi, fasa, serta delaywaktu yang bersifat random.
Sesuai namanya, large scalefading memberikan representasirata-rata daya sinyal terima dalamsuatu daerah yang luas.
Statistik dari large scale fadingmemberikan cara perhitunganuntuk estimasi pathloss sebagaifungsi jarak.
Kuat sinyal (dB)
Jarak
Definisi : local mean ( time averaged) dari variasi sinyal
Large Scale Fading disebabkankarena akibat keberadaan obyek-obyek pemantul serta penghalangpada kanal propagasi sertapengaruh kontur bumi,menghasilkan perubahan sinyaldalam hal energi, fasa, serta delaywaktu yang bersifat random.
Sesuai namanya, large scalefading memberikan representasirata-rata daya sinyal terima dalamsuatu daerah yang luas.
Statistik dari large scale fadingmemberikan cara perhitunganuntuk estimasi pathloss sebagaifungsi jarak.Modul 2 Large Scale Fading
Equal level main & reflected pathLower level reflected path
Rx Level
WidebandChannel
NarrowbandChannel
Frequency
Channel Frequency Responset
t
t
t
Channel PulseResponse
Direct Wave
Reflected WaveResultant
Sinyal multipath juga akan menyebabkan distorsi sinyal / cacat sinyal.Problem ini secara khusus berkaitan dengan bandwidth sinyal yangdigunakan dalam komunikasi mobile, dan juga karena respon pulsayang berbeda dari sinyal multipath
Equal level main & reflected pathLower level reflected path
Rx Level
WidebandChannel
NarrowbandChannel
Frequency
Channel Frequency Responset
t
t
t
Channel PulseResponse
Direct Wave
Reflected WaveResultant
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
KANAL MULTIPATH FADINGKANAL MULTIPATH FADINGFADING :Fenomena fluktuasi daya sinyal terima akibat adanyaproses propagasi dari gelombang radio.
Pengaruh fading terhadaplevel sinyal terima adalahdapat menguatkan ataupunmelemahkan tergantungphasa dari sinyal resultanmasing-masing path.
CA
D
BR eceiverTransm itter
Pengaruh fading terhadaplevel sinyal terima adalahdapat menguatkan ataupunmelemahkan tergantungphasa dari sinyal resultanmasing-masing path.
CA
D
BR eceiverTransm itter
A: direct pathB: reflectionC: diffractionD: scattering
PR
PR_thres
t0Modul 2 Large Scale Fading
Multipath dalam kanal radio menyebabkan :
Lingkungan kanal radio mobile ( indoor / outdoor ) seringkalitidak terdapat lintasan gelombang langsung antara Tx danRx, sedemikian daya terima adalah superposisi dari banyakkomponen gelombang pantul masing-masing memilikiamplitudo dan fasa saling independen
Multipath Fading , atau Short Term Fading
• Perubahan yang cepat dari amplituda kuat sinyal• Modulasi frekuensi random berkaitan dengan efek
Doppler pada sinyal multipath yang berbeda-beda• Dispersi waktu (echo) yang disebabkan oleh delay
propagasi multipath
Modul 2 Large Scale Fading
IntroductionWhy is it important to understand the characteristicsof wireless channel ?
– To determine the most appropriate signal design (source, channelcoding, and modulation)
– To develop new technologies in the radio signal transmitters andreceivers
– In multiuser communications, channel access scheme must bedone as efficiently as possible.
– In cellular systems, coverage of the desired signal is computed asaccurately as possible excess power would result in excessiveinterference as well.
– In cellular communication systems, to ensure the communicationconnection from cell to cell, then the lowest allowable level to bedetermined.
Modul 2 Large Scale Fading
– To determine the most appropriate signal design (source, channelcoding, and modulation)
– To develop new technologies in the radio signal transmitters andreceivers
– In multiuser communications, channel access scheme must bedone as efficiently as possible.
– In cellular systems, coverage of the desired signal is computed asaccurately as possible excess power would result in excessiveinterference as well.
– In cellular communication systems, to ensure the communicationconnection from cell to cell, then the lowest allowable level to bedetermined.
• Ideal Channel
• Ideal channel passed all the spectrum of the signal without distortion(called BW infinite channel with a 'flat' frequency response for allfrequencies)
• signal attenuation and the error is only caused by the AWGN (AdditiveWhite Gaussian Noise).
• Received signal is a deterministic quantity which the characteristicsexpressed by using the statistical properties of the AWGN (Gaussiandistributed).
Transmitted bit
Ideal channel
AWGN
detection
Introduction
Modul 2 Large Scale Fading
• Ideal Channel
• Ideal channel passed all the spectrum of the signal without distortion(called BW infinite channel with a 'flat' frequency response for allfrequencies)
• signal attenuation and the error is only caused by the AWGN (AdditiveWhite Gaussian Noise).
• Received signal is a deterministic quantity which the characteristicsexpressed by using the statistical properties of the AWGN (Gaussiandistributed).
Introduction
• Real channel (Physical Channel) :
• Physical channel always has a limited bandwidth• Only a significant component of the signal spectrum that passed
through the physical channel, in other words the signal isdistorted
• Signal bandwidth must be smaller or equal to the coherencebandwidth of the channel for relatively no distortion. The questionis: How to obtain the BW signal is smaller than coherentbandwidth of the channel?
Transmitted bit
PhysicalChannel
AWGN
detection
Modul 2 Large Scale Fading
• Real channel (Physical Channel) :
• Physical channel always has a limited bandwidth• Only a significant component of the signal spectrum that passed
through the physical channel, in other words the signal isdistorted
• Signal bandwidth must be smaller or equal to the coherencebandwidth of the channel for relatively no distortion. The questionis: How to obtain the BW signal is smaller than coherentbandwidth of the channel?
Introduction
2m
2
2)mm(
m
e2
1)m(p
Probability Distribution Function (PDF) of a lognormal distributedrandom variable is represented as follows :
Modul 2 Large Scale Fading
wherem = normal random variable signal strength(dBm)
= Average (mean) signal strength (dBm)m = standard deviationm
Introduction (Free Space Prop. Model)
Isotropic antenna: power is distributedhomogeneously over surface area of a sphere.
Modul 2 Large Scale Fading
Isotropic antenna: power is distributedhomogeneously over surface area of a sphere.
Received power is power through effective antennasurface over total surface area of a sphere of radius d
(Free Space Prop. Model), continued
The power density w atdistance d is
where PT is the transmitpower.
24 dPw T
Modul 2 Large Scale Fading
The power density w atdistance d is
where PT is the transmitpower.
R TP AdP
4 2
The received power is
with A the `antenna aperture' orthe effective receiving surface area.
(Free Space Prop. Model), continued
The antenna gain GR isrelated to the aperture Aaccording to
Thus the received signalpower is
G RA 4
2
2
d4GGP=P
d41
4GP=P
RTTR
2
2
RTR
Modul 2 Large Scale Fading
The antenna gain GR isrelated to the aperture Aaccording to
Thus the received signalpower is
2
d4GGP=P
d41
4GP=P
RTTR
2
2
RTR
Received power decreases with distance,PR :: d-2
Received power decreases with frequency, PR :: f -2
Cellular radio planning: Path Loss in dB:Lfs = 32.44 + 20 log (f / 1 MHz) + 20 log (d / 1 km)
Microwave and Satellite Communications ....• Friis transmission formula,
• Assumption: there is only a direct wave from the sender to the receiver• Radio link designed for local Fresnell I (R1) are free of obstructions. High
antenna tower at the transmitter and the receiver is determined in such away as to guarantee the line of sight conditions
)Km()MHz(P Dlog20flog2045,32L
22 Introduction
• Friis transmission formula,
• Assumption: there is only a direct wave from the sender to the receiver• Radio link designed for local Fresnell I (R1) are free of obstructions. High
antenna tower at the transmitter and the receiver is determined in such away as to guarantee the line of sight conditions
Fresnell_Iradius
21
1hh4R
Modul 2 Large Scale Fading
Plain Earth Propagation Model…. (Egli’s Model)
• As the basic theory of wave trajectory analysis inmobile communication
• Key words: there are multiple paths (multipath): 1direct wave and a wave reflection.
• Analysis of the signal path in mobilecommunications is much different from the LOSmicrowave communications because signals havediffraction, much obstructed, and a lot of reflection.
23 Introduction
• As the basic theory of wave trajectory analysis inmobile communication
• Key words: there are multiple paths (multipath): 1direct wave and a wave reflection.
• Analysis of the signal path in mobilecommunications is much different from the LOSmicrowave communications because signals havediffraction, much obstructed, and a lot of reflection.
Empirical Model….• Derived from measurements and intensive research in an area• Attenuation curves are plotted and the results made formulations• Popular attenuation formula : Okumura-Hata, dan Walfish Ikegami• Another path attenuation models developed by: Lee, Egli, Carey,
Longley-Rice, Ibrahim-Parson, etc
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Karakteristik propagasi pada jaringan bergerak (seluler)berbeda dibandingkan dengan karakteristik propagasipada jaringan tetap. Pada jaringan bergerak fading yangterjadi lebih hebat dan fluktuatif dibandingkan denganjaringan tetap.
Untuk menghitung path loss pada propagasi jaringanseluler telah banyak dilaakukan percobaan dan penelitian.Beberapa diantaranya yang sering dipakai adalah
Untuk menghitung path loss pada propagasi jaringanseluler telah banyak dilaakukan percobaan dan penelitian.Beberapa diantaranya yang sering dipakai adalah
Model Hata Model Walfisch-Ikegami ( COST-231 ) Model Okumura dll
Modul 2 Large Scale Fading
Macrocells In early days, the models were based on emprical
studies Okumura did comprehesive measurements in
1968 and came up with a model. Discovered that a good model for path loss was a simple power
law where the exponent n is a function of the frequency, antennaheights, etc.
Valid for frequencies in: 100MHz – 1920 MHzfor distances: 1km – 100km
PROPAGATION MODEL
In early days, the models were based on empricalstudies
Okumura did comprehesive measurements in1968 and came up with a model. Discovered that a good model for path loss was a simple power
law where the exponent n is a function of the frequency, antennaheights, etc.
Valid for frequencies in: 100MHz – 1920 MHzfor distances: 1km – 100km
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Okumura Model L50(d)(dB) = LF(d)+ Amu(f,d) – G(hte) – G(hre) – GAREA
– L50: 50th percentile (i.e., median) of path loss– LF(d): free space propagation pathloss.– Amu(f,d): median attenuation relative to free space
Can be obtained from Okumura’s emprical plots shown in the book (Rappaport),page 151.
– G(hte): base station antenna heigh gain factor– G(hre): mobile antenna height gain factor– GAREA: gain due to type of environment
G(hte) = 20log(hte/200) 1000m > hte > 30m G(hre) = 10log(hre/3) hre <= 3m G(hre) = 20log(hre/3) 10m > hre > 3m
hte: transmitter antenna height hre: receiver antenna height
L50(d)(dB) = LF(d)+ Amu(f,d) – G(hte) – G(hre) – GAREA
– L50: 50th percentile (i.e., median) of path loss– LF(d): free space propagation pathloss.– Amu(f,d): median attenuation relative to free space
Can be obtained from Okumura’s emprical plots shown in the book (Rappaport),page 151.
– G(hte): base station antenna heigh gain factor– G(hre): mobile antenna height gain factor– GAREA: gain due to type of environment
G(hte) = 20log(hte/200) 1000m > hte > 30m G(hre) = 10log(hre/3) hre <= 3m G(hre) = 20log(hre/3) 10m > hre > 3m
hte: transmitter antenna height hre: receiver antenna height
Cellular radio planning: Path Loss in dB:Lfs = 32.44 + 20 log f (MHz) + 20 log d (km)
LdPPdBPLr
t22
2
4log10log10)(
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Hatta Model Valid from 150MHz to 1500MHz A standard formula For urban areas the formula is:
– L50(urban,d)(dB) = 69.55 + 26.16logfc - 13.82loghte – a(hre) +(44.9 – 6.55loghte) log d
wherefc is the ferquency in MHzhte is effective transmitter antenna height in meters (30-200m)hre is effective receiver antenna height in meters (1-10m)d is T-R separation in kma(hre) is the correction factor for effective mobile antenna height which
is a function of coverage area
a(hre) = (1.1logfc – 0.7)hre – (1.56logfc – 0.8) dB
for a small to medium sized city
Valid from 150MHz to 1500MHz A standard formula For urban areas the formula is:
– L50(urban,d)(dB) = 69.55 + 26.16logfc - 13.82loghte – a(hre) +(44.9 – 6.55loghte) log d
wherefc is the ferquency in MHzhte is effective transmitter antenna height in meters (30-200m)hre is effective receiver antenna height in meters (1-10m)d is T-R separation in kma(hre) is the correction factor for effective mobile antenna height which
is a function of coverage area
a(hre) = (1.1logfc – 0.7)hre – (1.56logfc – 0.8) dB
for a small to medium sized city
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Daerah urban
Model Hata pada daerah urban berlaku rumus sbb :
L50(u) = C1+ C2 log ( f ) - 13,82 log (hb) – a (hm) + { 44,9 – 6,55log (hb) } log (d).
Dimana :f = frekuensi (MHz)hb = tinggi antena BTS (m)hm = tinggi antena MS (m)d = jarak antara BTS – MS (km)C1 = 69,55 untuk 400 f 1500
= 46,3 untuk 1500 < f 2000C2 = 26,16 untuk 400 f 1500
= 33,9 untuk 1500 < f 2000
f = frekuensi (MHz)hb = tinggi antena BTS (m)hm = tinggi antena MS (m)d = jarak antara BTS – MS (km)C1 = 69,55 untuk 400 f 1500
= 46,3 untuk 1500 < f 2000C2 = 26,16 untuk 400 f 1500
= 33,9 untuk 1500 < f 2000
a(hm) = {1,1log (f) - 0,7} hm – {1,56 log(f) – 0,8 }
Modul 2 Large Scale Fading
Daerah dense urbanModel Hata pada daerah urban berlaku rumus sbb :
L50(du) = C1+C2 log ( f )-13,82 log (hb) – a (hm)+{ 44,9 – 6,55log (hb) } log (d)+Cm
Dimana :f = frekuensi (MHz)hb = tinggi antena BTS (m)hm = tinggi antena MS (m)d = jarak antara BTS – MS (km)C1 = 69,55 untuk 400 f 1500
= 46,3 untuk 1500 < f 2000C2 = 26,16 untuk 400 f 1500
= 33,9 untuk 1500 < f 2000Cm = 3 dB
f = frekuensi (MHz)hb = tinggi antena BTS (m)hm = tinggi antena MS (m)d = jarak antara BTS – MS (km)C1 = 69,55 untuk 400 f 1500
= 46,3 untuk 1500 < f 2000C2 = 26,16 untuk 400 f 1500
= 33,9 untuk 1500 < f 2000Cm = 3 dB
a(hm) = 3,2{ log(11,75hm) } 2 – 4,97
Modul 2 Large Scale Fading
Daerah suburban
L50(su) = L50(u) – 2{log(f/28)}2 – 5,4
Daerah rural terbuka
L50(rt) = L50(u) – 4,78{log(f)}2 + 18,33log(f) – 40,94
Modul 2 Large Scale Fading
Kelebihan : mudah digunakan ( langsung dimasukkan pada rumus jadi )Kekurangan: tidak ada parameter eksak yang tegas antara daerah kota,
daerah suburban, maupun daerah terbuka
Lu = 69,55 + 26,16log fC – 13,83log hT – a(hR) + [44,9 – 6,55 log hT ] log dLu = 69,55 + 26,16log fC – 13,83log hT – a(hR) + [44,9 – 6,55 log hT ] log dDimana ,
150 fC 1500 MHz30 hT 200 m , 1 hr 10 m1 d 20 kma(hR) adalah faktor koreksi antenna mobile yang nilainya adalah sebagaiberikut :
Daerah kota
Okumura-Hata Prediction ModelPrediction Model
150 fC 1500 MHz30 hT 200 m , 1 hr 10 m1 d 20 kma(hR) adalah faktor koreksi antenna mobile yang nilainya adalah sebagaiberikut :
• Untuk kota kecil dan menengah,a(hR) = (1,1 log fC – 0,7 )hR – (1,56 log fC – 0,8 ) dB, dimana, 1 hR 10 m• Untuk kota besar,
a(hR) = 8,29 (log 1,54hR )2 – 1,1 dB fC 300 MHza(hR) = 3,2 (log 11,75hR )2 – 4,97 dB fC > 300 MHz
Modul 2 Large Scale Fading
Daerah Suburban
4,528flog2LL
2C
usu
Daerah Open Area
94,40flog33,18)f(log78,4LL c2
cuo
Okumura-Hata Prediction Model
94,40flog33,18)f(log78,4LL c2
cuo
Modul 2 Large Scale Fading
Merupakan formula pengembangan rumus Okumura Hata untuk frekuensi PCS ( 2GHz)
COST-231 ( PCS Extension Hata Model)
MTRTcu C)logd6,55logh(44,9)a(hlogh13,82logf33,946,3L
dimana , 1500 MHz fC 2000 MHz30 m hT 200 m ,1 m hR 10 m1 d 20 kma(hR) adalah faktor koreksi antena mobile yang nilainya sebagai berikut :
Prediction Model
• Untuk kota kecil dan menengah,a(hR) = (1,1 log fC – 0,7 )hR – (1,56 log fC – 0,8 ) dBdimana, 1 hR 10 m
• Untuk kota besar,a(hR) = 8,29 (log 1,54hR )2 – 1,1 dB fC 300 MHza(hR) = 3,2 (log 11,75hR )2 – 4,97 dB fC 300 MHz
dan,CM =
0 dB untuk kota menengah dan kotasuburban3 dB untuk pusat kota metropolitan
1500 MHz fC 2000 MHz30 m hT 200 m ,1 m hR 10 m1 d 20 kma(hR) adalah faktor koreksi antena mobile yang nilainya sebagai berikut :
Modul 2 Large Scale Fading
COST231 Walfish Ikegami Model
Cost231 Walfish Ikegami Model digunakan untuk estimasi pathloss untuklingkungan urban untuk range frekuensi seluler 800 hingga 2000 MHz.
Wallfisch/Ikegami model terdiri dari 3 komponen :• Free Space Loss (Lf)• Roof to street diffraction and scatter loss (LRTS)• Multiscreen loss (Lms)
LC =Lf + LRTS + Lms
Lf ; untuk LRTS + Lms < 0
Prediction Model
LC = Lf ; untuk LRTS + Lms < 0
• Lf = 32.4 + 20 log10 R + 20 log10 fc dimana R (km); fc (MHz)
• LRTS = -16.9 + 10 log10 W + 20 log10 fc + 20 log10 hm + L
di manaL =
-10 + 0.354 ; 0 < < 352.5 + 0.075( - 35) ; 35 < < 554.0 – 0.114( - 55) ; 55 < < 90
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
• Lms = Lbsh + ka + kd log10 R + kf log10 fc - 9log10 bdimana Lbsh =
-18 + log10 (1 + hm ) ; hb < hr ; hb > hr
ka =54 ; hb > hr54 + 0.8hb ; d > 500 m hb < hr54 + 0.8 hb . R ; 55 < < 90
Catatan : Lsh dan ka meningkatkan path loss untuk hb yang lebih rendah.
COST231 Walfish Ikegami ModelPrediction Model
Catatan : Lsh dan ka meningkatkan path loss untuk hb yang lebih rendah.
kd =18 ; hb > hr18 – 15 (hb/hr ) ; hb < hr
kf =4 + 0.7 (fc/925 - 1
4 + 1.5 (fc/925 - 1)
; Untuk kota ukuran sedang dansuburban dengan kerapatan pohoncukup moderat
; Pusat kota metropolitan
Modul 2 Large Scale Fading
Model ini valid ; d ≤ 5km, hb ≤ 50m, micro cell, data basegedung dan jalan yang lengkap
Pada prinsipnya model ini terdiri dari 3 elemen yaitu :- Free Space Loss,- Rooftop to Street Diffraction Scatter Loss,- Multi Screen Loss, seperti rumus berikut :
L50 = Lf + Lrts + LmsL50 = Lf + Lrts + Lms
L50 = Lf , jika Lrts + Lms ≤ 0
Lf = free space loss, Lrts = rooftop to street diffraction & scatterdan Lms = multi screen loss
Seperti disinggung di depan Lf dapat dihitung dengan rumus
Lf = 32,4+ 20log r + 20 log fc (dB)
Modul 2 Large Scale Fading
Lrts dapat dihitung dengan rumus
Lrts = - 16,9 +10log W + 10log fc + 20log hm + L0 (dB)
Variable yang mendukung rumus di atas ditunjukan sepertigambar berikut
hb
R
hb
hr
hb
b w
hm
hm
W lebar jalan (m) dan hm = hr – hm (m)
Lrst = 0 jika hm ≤ 0
Modul 2 Large Scale Fading
building
building building
building
building building
L0 = -10 +0,354 dB untuk 00 < 350
L0 = 2,5 + 0,075(-35) dB untuk 350≤ < 550
L0 = 4 - 0,114(-55) dB untuk 550≤ ≤ 900
Modul 2 Large Scale Fading
Lms dapat dihitung dengan rumus
Lms = Lbsh + ka + kd log r + kflog fc – 9logb (dB)
Lbsh = -18log(1+ )hb Untuk hb
hb
> 0
= 0 Untuk ≤ 0
Ka = 54
Ka = 54 – 0,8 hb
Untuk hb > 0
Untuk r 0,5 dan hb ≤ 0Ka = 54 – 0,8 hb
Ka = 54 – 1,6 hb r
Untuk r 0,5 dan hb ≤ 0
Untuk r < 0,5 dan hb ≤ 0
Kd = 18 Untuk hb > 0
Kd = 18 -15 ( hbhr
) hbUntuk ≤ 0
Kf = -4 +0,7 ( f925 -1 ) Untuk urban dan suburban
Kf = -4 +1,5 ( f925 -1 ) Untuk dense urban
Modul 2 Large Scale Fading
Tentukan loss propagasi dengan menggunakan model Hatadan COST 231 antara BTS dan MS pada daerah dense urbanjika diketahui data-data sbb :
f = 1887 MHz, hm = 1,5 m , hb = 30 m, r = 3km , hr = 30 m = 900 , b = 30 m, W = 15 m
Modul 2 Large Scale Fading
ro = 1mil= 1,6 km
rPro
PrP P
rr
ffr ro
o o
n
o
. . .
P Prrn
ffr ro
o oo
. log . log10 10
Dalam persamaan linear,
Dalam persamaan logaritmik (dB),
Lee’s Prediction ModelPrediction Model
P Prrn
ffr ro
o oo
. log . log10 10
Pr = Daya terima pada jarak r dari transmitter.Pro = Daya terima pada jarak ro = 1 mil dari
transmitter.= Slope / kemiringan Path Loss
n = Faktor koreksi, digunakan apabila adaperbedaan frekuensi antara kondisi saateksperimen dengan kondisi sebenarnya.
o = Faktor koreksi, digunakan apabila adaperbedaan keadaan antara kondisi saateksperimen dengan kondisi sebenarnya.
Kondisi saat eksperimen dilakukan,1. Operating Frequency = 900 MHz.2. RBS antenna = 30.48 m3. MS antenna = 3 m4. RF Tx Power = 10 watt5. RBS antenna Gain = 6 dB over
dipole l/2.6. MS antenna Gain = 0 dB over
dipole l/2.
Modul 2 Large Scale Fading
L0 and are obtained from table
where
hb in m
PT in W
Gb = BS antenna gain in scalar
hm in mfc = carrier frequency in MHzf0 = In an 900 MHz frequency referencen = 2 - 3
Lee Models00 log FdLLLee
543210 FFFFFF
2
1 5.30
bhF
Environment L0 [dB] Free Space 91.3 20Open (Rural) 91.3 43.5Suburban 104.0 38Urban:Tokyo 128.0 30Philadelpia 112.8 36.8Newark 106.3 43.1
Modul 2 Large Scale Fading
L0 and are obtained from table
where
hb in m
PT in W
Gb = BS antenna gain in scalar
hm in mfc = carrier frequency in MHzf0 = In an 900 MHz frequency referencen = 2 - 3
2
1 5.30
bhF
102TPF
43bGF
2
34
mhF
nc
ffF
05
Environment L0 [dB] Free Space 91.3 20Open (Rural) 91.3 43.5Suburban 104.0 38Urban:Tokyo 128.0 30Philadelpia 112.8 36.8Newark 106.3 43.1
Pro and didapat dari data hasil percobaan
in free space,Pro = 10-4.5 mWattsg = 2
in an open area,Pro = 10-4.9 mWattsg = 4.35
in urban area (Philadelphia),Pro = 10-7 mWattsg = 3.68
in urban area (Tokyo),Pro = 10-8.4 mWattsg = 3.05
ao = faktor koreksi
o = 1 . 2 . 3 . 4 . 5
2
1 (m)48.30(m)riilstationbaseantenatinggi
v
(m)3(m)riilunitmobileantennatinggi
2
Lee’s Prediction Model
in an open area,Pro = 10-4.9 mWattsg = 4.35
in sub urban area,Pro = 10-6.17 mWattsg = 3.84
in urban area (Tokyo),Pro = 10-8.4 mWattsg = 3.05
v
(m)3(m)riilunitmobileantennatinggi
2
(watts)10(watts)riilpemancardaya
3
42dipoleantenatdhriilstationbaseantenagain
4
12dipoleantenathd.riilunitmobileantenagain
54
Modul 2 Large Scale Fading
Lee’s Prediction Model
n diperoleh dari percobaan / empiris
dec/dB30ndec/dB20
Harga n diperoleh dari hasil percobaan yangdilakukan oleh Okumura dan Young
Berdasarkan eksperimen oleh Okumuran=30 dB/dec untuk Urban Area.
Correction factor to determine vin a2
v = 2,for new mobile-unit antenna heigh > 10 m
v = 1,for new mobile-unit antenna heigh < 3 mBerdasarkan eksperimen oleh Okumura
n=30 dB/dec untuk Urban Area.
Berdasarkan eksperimen oleh Youngn=20 dB/dec untuk Sub.Urban Areaatau Open Area
n hanya berlaku untuk frekuensi operasi30 sd. 2,000 MHz
v = 1,for new mobile-unit antenna heigh < 3 m
Modul 2 Large Scale Fading
3Jarak dalam mil
2 4 5 6 7 8 9 101
-110
-100
-90
-80
-70
-60
-50
-120
Signa
l stre
ngth
in dB
m
12
22
32
42
52
62
72
82
Signa
l stre
ngth
in dB
(mikr
oVolt
)
New York City ( Po = - 77 dBm, = 48 dB/dec )
Tokyo, Japan ( Po= - 84 dBm, = 30.5 dB/dec )
Philadelphia ( Po = - 70 dBm, = 36.8 dB/dec )
Newark ( Po = - 64 dBm, = 43.1 dB/dec )
Suburban ( Po = - 61.7 dBm, = 38.4 dB/dec )
Open Area ( Po = - 49 dBm, = 43.5 dB/dec )
Open Area ( Po = - 45 dBm, = 20 dB/dec )
Lee’s Prediction Model
3Jarak dalam mil
2 4 5 6 7 8 9 101
-110
-100
-90
-80
-70
-60
-50
-120
Signa
l stre
ngth
in dB
m
12
22
32
42
52
62
72
82
Signa
l stre
ngth
in dB
(mikr
oVolt
)
New York City ( Po = - 77 dBm, = 48 dB/dec )
Tokyo, Japan ( Po= - 84 dBm, = 30.5 dB/dec )
Philadelphia ( Po = - 70 dBm, = 36.8 dB/dec )
Newark ( Po = - 64 dBm, = 43.1 dB/dec )
Suburban ( Po = - 61.7 dBm, = 38.4 dB/dec )
Open Area ( Po = - 49 dBm, = 43.5 dB/dec )
Open Area ( Po = - 45 dBm, = 20 dB/dec )
Modul 2 Large Scale Fading
ro = 1mil= 1,6 km r1
Pro
Pr
r2
area 1 area 2
r
r1 r2r
area 1 area 2
1.6 km
Lee’s Pathloss Formula Untuk Berbagai Jenis KondisiLingkungan
r1 r2r1.6 km
o
n
o1o1
ror .ff.
rr.
rr.PP
21
o = 1 . 2 . 3 . 4 .
5
o
n
o1N12
o1
ror .ff.
rr.....
rr.
rr.PP
N21
persamaanumum,
Modul 2 Large Scale Fading
MOBILE
Building
IncidentWave = incident angle relative to streetBuilding
Building
Building
R
Diagram Parameter
w
b
Mobile
R
hb
hb
hrhmhm
Cell siteGROUND
Modul 2 Large Scale Fading
L [dB]=L (d0)+10 log (d/d0)
from table 3.2 (Rappa, pp 104)
Log Distance Path Loss Model
Environment Pathloss Exponent
Free Space 2Urban 2.7 - 3.5Shadowed Urban 3.0 - 5.0in building LOS 1.6 - 1.8in building Obstructed 4.0 - 6.0in factories Obstructed 2.0 - 3.0
Modul 2 Large Scale Fading
Environment Pathloss Exponent
Free Space 2Urban 2.7 - 3.5Shadowed Urban 3.0 - 5.0in building LOS 1.6 - 1.8in building Obstructed 4.0 - 6.0in factories Obstructed 2.0 - 3.0
L [dB]=L (d0)+10 log (d/d0) + X Shadowing effect + fading margin + availability
(Rappa, pp 104)
Log-normal Shadowing
Modul 2 Large Scale Fading
L [dB]=L (d0)+10 log (d/d0) + X Shadowing effect + fading margin + availability
(Rappa, pp 104)
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
Modul 2 Large Scale Fading
The measurement method with Regression Methods
• Select multiple locationsat distances d1 and takethe measurement ofpath loss
• Repeat for thedistance d2 and d3, etc.
• Plot of themean pathloss asa function of distance
Cell site(Tx)
d1 d2
d3
Modul 2 Large Scale Fading
• Select multiple locationsat distances d1 and takethe measurement ofpath loss
• Repeat for thedistance d2 and d3, etc.
• Plot of themean pathloss asa function of distance
Cell site(Tx)
Getting Mean and Standard Deviation
• Measurement isusually done for some typesof areas: Urban, suburban, andopen areas
• Measurements at constant radius from the BTS to producedifferent pathloss
• With the linear regression method,we can obtain the meanpathloss trend and standarddeviation around the average value
• Example for urban: path loss Slope = 33.2 dB / decade and Std dev. = 7 dB
Path loss [dB
]
urban
xxx
x x
x x x
x x
x x
x x
x x
o o o
o o o
o o
o o
o o
o o
o
o o
79
85
75
Modul 2 Large Scale Fading
• Measurement isusually done for some typesof areas: Urban, suburban, andopen areas
• Measurements at constant radius from the BTS to producedifferent pathloss
• With the linear regression method,we can obtain the meanpathloss trend and standarddeviation around the average value
• Example for urban: path loss Slope = 33.2 dB / decade and Std dev. = 7 dB Distance d [km]
Path loss [dB
]
suburban
open
xxx
x x
x x x
x x
x x
x x
x x
o o o
o o o
o o
o o
o o
o o
o
o o
# #
# #
# #
#
3 4 6
75