3_4_propagasi_selular_u

Laboratorium Telekomunikasi Radio dan Gelombang Mikro Laboratorium Telekomunikasi Radio dan Gelombang Mikro

Departemen

Departemen TTeknik eknik ElektroElektro Institut Teknologi Bandung Institut Teknologi Bandung

SISTEM KOMUNIKASI SELULAR SISTEM KOMUNIKASI SELULAR

(ET-5005) (ET-5005)

Dr

Dr. . IrIr. Adit . Adit KurniawanKurniawan, , M.Eng.M.Eng. [email protected] [email protected]

Minggu_3_dan_4: Propagasi Selular Minggu_3_dan_4: Propagasi Selular

ET-5005, Sistem Komunikasi Selular

Pendekatan

Pendekatan Analitik

Analitik dan Empirik

dan Empirik

•

• MobiMobile le Radio Radio ChanChannel nel CharaCharactericterisatiosationn •

• ThTheoreoretietical cal appapproaroachch  – Free space loss  – Free space loss

 – Plane earth path loss  – Plane earth path loss  – Diffraction loss

 – Diffraction loss •

• EmpiEmpiricalrical/pred/prediction iction apprapproachoach – – -- -- --– – LLeee e -- AAllsseebbrrooookk  –  – --•

• MeasuremeMeasurement nt of of large large scale scale and and application application in in coveragecoverage prediction

prediction •

Pendekatan

Pendekatan Analitik

Analitik dan Empirik

dan Empirik

•

• MobiMobile le Radio Radio ChanChannel nel CharaCharactericterisatiosationn •

• ThTheoreoretietical cal appapproaroachch  – Free space loss  – Free space loss

 – Plane earth path loss  – Plane earth path loss  – Diffraction loss

 – Diffraction loss •

• EmpiEmpiricalrical/pred/prediction iction apprapproachoach – – -- -- --– – LLeee e -- AAllsseebbrrooookk  –  – --•

• MeasuremeMeasurement nt of of large large scale scale and and application application in in coveragecoverage prediction

prediction •

MODEL PROP

MODEL PROPAGASI AGASI SISTEM SISTEM SELULARSELULAR

Model untuk memperkirakan redaman: Model untuk memperkirakan redaman:

• Model teoretis • Model teoretis ••

• Model Lee • Model Lee

• Persamaan Umum Redaman Propagasi • Persamaan Umum Redaman Propagasi •

• eer r rraaaan n t t eem m tt •

• Model Model Okumura-Okumura-HattaHatta

• Faktor Koreksi Undulasi • Faktor Koreksi Undulasi • Faktor Koreksi Kemiringan • Faktor Koreksi Kemiringan

Model Teoretis Sederhana Model Teoretis Sederhana

∆

∆

d

d =

= d

d

-

- d

d

Karakterisasi Propagasi

Karakterisasi Propagasi

Mobile Radio Propagasi Mobile Radio Propagasi Large-scale propagation

Large-scale propagation SSmmaa --ssccaa e pe prrooppaaggaattiioonn

Mean signal

Mean signal Signal VariationSignal Variation

•Theoretical approach •Theoretical approach ime ime spreading of  spreading of  ssii nnaall ime ime variation of  variation of  •Empirical/pred

•Empirical/prediction iction approachapproach •Statistical modelling

•Statistical modelling og

ognonormrma a or or ararge ge scscaa e e papa loss)

Model Teoretis Sederhana

2

1

aya yang ter ma me a u ge om ang angsung:

r  t t or 

/

d

4

π

λ

Gt = Gain antena penerima (MS) d = Jarak emancar - enerima

λ

gelombang pantul: 2 2

1

cos

s n

/

d

4

π

λ

ω

ω

Model Teoretis Sederhana

engan menurun an persamaan a am tan a mut a , ma a diperoleh persamaan sederhana sebagai berikut:

2 2 2 1 r  t t r 

d

G

G

P

P

Persamaan tersebut menghasilkan dua kondisi yang sesuai dg percobaan, yaitu:

 Path loss sebesar 40 dB/ dekade (sebanding dengan d-4₎

atau 12 dB/ oktaf.

enam a an pat oss ar ara 1 e 2 = 40 og 2 1  Pertambahan gain sebesar 12 dB/dekade atau 6 dB/oktaf

.

Sedangkan hasil yang tidak sesuai dg percobaan dan perlu

 Tidak terdapat faktor interferensi (pjg gel.) ,

Rumus empiris: P_r  = f -n _{dengan 2 < n < 3}

 Teoretis: penambahan tinggi antena pada MS: 6 dB/ oktaf. emp r s: pengurangan ngg an ena -nya: ga n er urang dB.

Theoretical approach

• Received power density at distance

W

G

P

=

t 

4

π

• Received ower when Rx

W

G

λ

G

=

₄

_π

_d

₄

_π

df 

4

c

G

G

d

4

G

G

W

=

⎜

⎝  π

 ⎠

⎟

=

⎜

⎝  π

 ⎠

⎟

Plane earth propagation

[

]

_G

_G

₁

_-

_e

W

_G

_G

h

h

W

⎟

⎜

⎛ 

=

=

ρ

⎟

⎜

⎛  λ

=

Path loss model plane earth is

Diffraction Loss

d

d

_d

d

d

h

+

d

d

2

≈

Fresnel zone (path clearance)

v

d

d

h

2

d

2

π

=

+

π

=

∆

π

=

∆

 ⎞

⎜

⎛  +

=

_h

2

d

d

v

• The n-th Fresnel zone is area between Tx and Rx inside

2 1

the ellipsoide with radius of its cross section of r _n where

2 1 n

d

d

r 

+

=

=

Diffraction Loss

Diffraction loss can be computed from

0

When v=0 (h=0) diffraction

space loss

When v=-0.8 diffraction

loss is negligible (56 % of

The 1

_{Fresnel zone is}

clear)

Empirical Prediction Approach

• Based on signal measurement

–

-

-– Lee

- Alsebrook

– g

- ra m- e erson

•

measurement

 – 

 – COST-231 (Europe)

Okumura Model

• Okumura develop propagation model based on extensive signal measurements in Kanto (near Tokyo)

.

• Propagation environments are classified into:   – Urban areas hi hl dense o ulated areas  – Suburban areas (moderate population)

– Open/rural areas (few population, rare building/  • Okumura develop propagation loss (mean and variance)

in the form of curves of propagation loss vs distance for eren parame ers, suc as requenc es, an enna heights, ground curvature/undulation, etc).

•

Hatta and COST-231 Models

• Masaharu Hatta makes use of Okumura model and formulas, therefore the name of Okumura-Hatta model.

-mathematical formula of Hatta model for use in DCS/ PCS frequencies (1800 MHz).

• Hatta model is valid for urban area, and corrections factors are provided for suburban and open areas.

• Hatta dan COST-231 models are the most common models used in cellular system due to their simple use with

Okumura –Hatta Model

For urban area:

L_pu [dB] = 69.55 + 26.16 log f  – 13.82 log h _b – a(h _m) + (44.9 – 6.55 log h _b) log d 

Model Okumura - Hatta

•

umura me a u an perco aan

aera

o yo g

menggunakan:

•

• Tinggi antena Ms : 3 m

• Hatta men atakan hasil ercobaan Okumura dalam

 bentuk persamaan:

KLASIFIKASI DAERAH PELAYANAN

RUMUS REDAMAN PERAMBATAN

−

−

=

]

....[

log

)

log

55

,

6

9

,

44

(

h

 R

dB

−

+

bergantung kepada tipe daerah urban yang dibagi sebagai berikut: Urban

]

)....[

8

,

0

log

56

,

1

(

)

7

,

0

log

1

,

1

(

)

(

h

 f 

h

 f 

dB

a

=

−

−

−

Medium Small City:

Area

 MHz

 f 

h

 f 

h

a

(

)

=

8

,

29

(log

.

1

,

54

)

−

1

,

1

<

200

(

)

=

3

,

2

(log

.

11

,

75

)

−

4

,

97

<

400

Keteran an

• f

= frekuensi kerja yg berharga: 150 MHz – 1500MHz.

• h = tinggi antena stasiun tetap (RBS): 30m – 200m.

• h

= tinggi antena stasiun mobile (MS): 1m – 3m.

Model Lee...

Dua pendekatan umum untuk menentukan 2 parameter tsb. : dengan hasil pengukuran yang telah ditabelkan di atas, maka harus dilakukan pengukuran.

n

γ

)

linier 

(

f 

r 

r 

P

P

α

f 

r 

f 

r 

r = ara ar

e

m m

r 

= jarak dari BS ke MS 1,6 km.

γ

= konstanta propagasi dalam dB/dekade

α

= faktor koreksi parameter terhadap keadaan

sebenarnya, antara lain parameter:

tinggi

antena BS (

1

), tinggi antena MS (

), daya

 pancar 

3

, ga n antena

, ga n

antena MS (

Model Lee...

Kondisi standar yang digunakan Lee, dalam mencari

konstanta propagasi:

•

Frekuensi f 

: 900 MHz

• Tinggi BS: 30,48 m (100 ft)

• aya pa a antena

:

att

m

• Gain antena BS: 6 dB terhadap dipole

• Gain antena MS: 0 dB terhapadap dipole

engan

mengguna an

ata

terse ut,

ee

melakukan percobaan di berbagai daerah dengan

berikut.

Model Lee

(Persamaan Umum)

Perkiraan area ke area menurut Model Lee membutuhkan 2  parameter:

• , _ro

• Kemiringan redaman atau path loss slope (

Γ

Dua pendekatan umum untuk menentukan 2 parameter tsb.: • em an ng an t pe aera stru tur angunan

Lee Model

Lee formulated the path loss of being

L

[dB] =

L

+

log

d ; 

with

L

is path loss at

d 

= 1

km and is the path loss slope.

Area L₀ [dB] (dB/decade]

Free space 91.2 20

pen rura area . .

Suburban area 104.3 38.4

. .

Philadelphia 112.8 36.8

.

Egli Model

• Based on Plane Earth Theoretical model with correction factors

•

Lp 

[dB] = 120 + 40 log

d 

– 20 log

h 

– 

20 log

h 

+

• Where

h 

h 

= 20 log (

f 

 /40)

.

• Egli model is derived from propagation measurement using .

• Egli model is therefore has a limited application for such an .

Blomquist-Laded Model

• This model considers the combination of free space,

plane earth, and diffraction loss models together.

• The model is expressed as

 – 

=

– 

p  ree space p ane ear  ree space

(

L

)

_}

•

,

diffraction loss is computed using multiple diffraction

loss from Bullington, Epstein Peterson, and Deygout

models.

• For situation with no diffraction, this model become

the plane earth model

Alsebrook Model

and Bath at frequencies of between 75 and 450 MHz.

• For flat areas L_p  [dB] = L_{plane earth} +L_B  + , where LB  is frequencies.

• For hilly areas L_p [dB] = L_{free space} +{(L_{iplane earth} – L_{free space})2 2 1/2

diffraction B 

• Correction for building is

16

10

Wfx

548

log

20

]

dB

[

L

⎜

⎟

+

⎝ 

−

=

Where h o is average height of building, hm  is mobile antenna height, effective width of street, and f  is carrier frequency.

• Correction of carrier frequency is increasing linearly from 0 to 15 dB as frequency increases from 200 to 500 MZ

Ibrahim-Peterson Model

• Based on measurement in London areas at freq 168 – 900 MHz with Base antenna height 46 m.

signal measurement, which is then correlated with plane earth model for corrections.

• Path loss model is L_p [dB] = 40 log d – 20 log(h _b h _m ) + = 2 0 + f /40 +0.18 L – 0.34 H +K 

ere

L = land use factor (percentage of area covered by H  = terrain factor (different of average ground height

between Tx and Rx)

K  = urbanisation factor (K  = 0.094 U  – 5.9 [dB]), U  is the percentage of building having 4 or more floors)

Path Loss Measurement

The received signal looks like this

•

e proper measuremen

s ance s =

λ

because if measurement distance is too

s or

may no g ve

e mean va ue

(signal still varying) and if too long

may

average ou

arge sca e

arge sca e

variation is smoothed out).

• The number of measurement samples n 

>36 for 90 % confidence interval.

Regression from Measurement Data

d1

And perform

measurement For the mean

d _{1  d}  2  d 

path loss

,

Plot the mean value of Path

loss as a function of

Distance

Obtain the Mean and Std Deviation

, suburban, and open areas.

• At a constant radius,

path loss can be  a P   t  _h  x x x x x o o o o o o 85

• From regression we can obtain the best fit for the

l    o   s   s   [    d  B  x x x x x x x o o o o o o 79 75

mean as well as the std deviation around the mean.  ]   su ur an o en x x x x o o o o o # # # # # #

• Example for urban: path loss Slope = 33.2

#

eca e an t ev.

Application in Coverage prediction

• Example at distance d 

=  4

km (see previous page for

urban area

• Path loss at 4 km is 79 dB.

•

for the mean value at 50 %

confidence level

• Since std. Dev for urban in

this example is 7 dB,

therefore

to

obtain

confidence level of 84%

(1

σ

) need margin of 7 dB

and for confidence of

97.7% 2

σ

nee marg n o

14 dB

JARAK JANGKAU BTS

Frekuensi kerja BS : 800 MHz Sistem modulasi FM dengan DF : 12 KHz

aya pancar : a

faktor derau : 7 dB

Tinggi antena BS : 40 m

Tinggi antena MS : 1,5 m

Gain antena BS : 8,5 dB

Redaman feeder di BS : 3,2 dB per 40

a. Menghitung nilai ambang penerimaan dg keandalan thd. Fading cepat

-= og , x . . ,

= - 128,9 dBm Faktor derau = 7 dB

Perhitungan Jarak Jangkau RBS

Cadangan fading cepat = 8,7 dB (untuk keandalan 90 %) TOTAL = - 103,2 dBm

  b. Nilai ambang penerimaan dengan keandalan terhadap fading lambat.

  Nilai ambang sesungguhnya (misal keandalan didasarkan pada 90% fading cepat dan 90% pada fading lambat) dihitung sbb.:

 x  x erf   x erf  r  r  P _{d  o} 30 , 1 ) ( 1 9 . 0 ) ( 1 ) (

−

=

→

−

=

−

=

≥

=

−

→

−

=

−

−

=

=

-md = nilai rata-rata sinyal penerimaan pada jarak d dari BS (logaritmik, dBm)

Perhitungan Jarak Jangkau RBS

c. Redaman di daerah Urban contoh di daerah urban :

 Nilai f _c = 800 MHz,

Tinggi antena BS h _b = 40 m ngg an ena _m = , m

Redaman dapat dinyatakan sebagai fungsi radius sel sbb.:

L = 69,55 + 26,16 lo 800 - 13,82 lo 40 - 0 + (44,9 - 6,55 log (40)) log R 

L = 123, 35 + 34,4 log R 

d. Jarak jangkau sebuah BS

A

Perhitungan Jarak Jangkau RBS d. Jarak jangkau sebuah BS

Jarak jangkau dihitung sbb.:

r 

=

-

-

- a

-94,36 = 40 - 2,5 8,5 - L + 2 - 3,2

=

,

Dari persamaan di halaman sebelumnya (49) diperoleh: L = 123,35 + 34,4 log R 

R = 2,88 km.

Jarak jangkauan BS tersebut dengan contoh data sederhana yang disajikan di atas menghasilkan radius sel = 2,88 km.

Pada kenyataan tentunya tidak sesederhana seperti contoh  perhitungan disini.

Contoh persoalan: Model Lee

• Kondisi Dengan Penghalang Contoh: . h 35m 60m 5 m 25m = .

Jawaban: Soal Model Lee Kondisi Dengan Penghalang Jawab: m dihitung hp

=

20

,

8

1

/

3

900

=

=

1

,

04

6000

4000

3

/

1

8

,

20

⎟

=

 ⎠

⎜

⎝ 

+

=

18

,

107

900

log

20

10

log

20

1

,

28

,

=

+

+

=

=

=

=

107

,

18

+

14

=

121

,

18

Example

• ’

BTS in urban area. The minimum signal level (receiver sensitivity) of the MS is – 100 dBm. BTS Tx power is 10 W at 40 m high, feeder loss at BTS is 7 dB, BTS Tx antenna gain is 13 dB, mobile Rx antenna gain is 3

, an set o y oss s . perat ng carr er req s . z.  – Compute cell radius using Okumura-Hatta Model.

 – If it were in free space condition, compute the received signal level at e .

• Answer

Rx_min = Tx – L_f + G_t – L_u +G_r – L_B  L_u=40 -7+13 +100+3-3 = 146

Hatta L_pu=69.55+26.16 log(1.8x103_{)-13.82 log(40) +}

[44.9-6.55 lo 40 lo R

146 = 154.7 – 22.14 + 34.4 log R  R = 2.5 km (cell radius). L_freespace = 32.45 + 20 log (1.8x103_{) + 20 log (2.5) = 105.5 dB}

x = – + – . + – = - . m ece ve signal level if freespace)