Download - Model Propagasi Selular(2)
SISTEM KOMUNIKASI NIRKABEL
Jati Fallat
Pendekatan Analitik dan Empirik Mobile Radio Channel Characterisation Theoretical approach
Free space lossPlane earth path lossDiffraction loss
Empirical/prediction approachOkumura-Hatta - Blomquist-LadelLee - AlsebrookEgli - Ibrahim Parson
Measurement of large scale and application in coverage prediction
Some examples
Karakterisasi Propagasi
Mobile Radio Propagasi
Large-scale propagation
Small-scale propagation
Mean signal
Signal Variation
Time spreading of signal
Time variation of channel
MODEL PROPAGASI SISTEM SELULAR
Model untuk memperkirakan redaman :• Model teoretis• Model empiris
• Model Lee• Persamaan Umum Redaman Propagasi• Perkiraan Titik demi Titik
• Model Okumura-Hatta• Faktor Koreksi Undulasi• Faktor Koreksi Kemiringan
Theoretical approachFree space formula Received power density at distance d when Tx antena
gain Gt is
Received power when Rx antenna gain Gt is
Ratio of Rx/Tx power is
Free space path loss is Lp(FS) [dB] = 32.45 + 20 log f + 20 log d
2tt
r d4GWP
4G
d4GWW r
2
2tt
r
2
rt
2
rtt
r
df4cGG
d4 GG
WW
Plane earth propagation
Path loss model plane earth is Lp(PE) = 120 + 40 log d – 20 log ht – 20 log hr
Tx Rx
ht hr
d
Diffraction Loss
The difference of path length between direct and diffracted ray is
TxRxd1 d2
h (positif)
Tx Rxd1 d2
h (negatif)
21
212
dddd
2h d
Fresnel zone (path clearance) The phase difference when h << d1 and h << d2 is
with v is diffraction parameter which can be expressed as
The n-th Fresnel zone is area between Tx and Rx inside the ellipsoide with radius of its cross section of rn where
2
21
212
v2dd
dd2h2d2
21
21
dddd2hv
21
21n dd
ddnhr
Empirical Prediction ApproachBased on signal measurement
Okumura - Blomquist-LadelLee - AlsebrookEgli - Ibrahim-Peterson
Mathematical Formulation based on signal measurementHatta (Japan)COST-231 (Europe)
Okumura –Hatta Model
Lp(open) = Lp(urban) –4.78(logf)2 + 18.33 log f – 40.94
For urban area:
Lpu [dB] = 69.55 + 26.16 log f – 13.82 log hb – a(hm) + (44.9 – 6.55 log hb) log d
Model Okumura – Hatta
KLASIFIKASIDAERAH
PELAYANANRUMUS REDAMAN PERAMBATAN
Urban Area
Lu = 69,55 +26,16 log fc – 13,82 log hb – a (hm) + (44,9– 6,55 log hb) log R……………..(dB)
Faktor koreksi untuk tinggi antena stasiun mobilyang bergantung kepada tipe daerah urban yangdibagi sebagai berikut :
Medium – small city :a (hm) = (1,1 log fc – 0,7) hm – (1,56 log fc – 0,8) ….(dB)Large City
a (hm) = 8,29 (log fc 1,54 hm)2 – 1,1 , fc < 200 MHza (hm) = 3,2 (log fc 11,75 hm)2 – 4,97 , fc > 400 MHz
Sub Urban Area Lsu = Lu (urban area) – 2 [log (fc/ 28)]2 – 5,4 ….(dB)Open Area Lo = Lu (urban area) – 4,78 (log fc)2 + 18,33 log fc –
40,94 ….(dB)
Keterangan :
fc = frekuensi kerja yang berharga : 150 MHz – 1500 MHzhb = tinggi antena stasiun tetap (RBS) : 30 m – 200 mhm = tinggi antena stasiun mobil (MS) : 1 m – 3 mR = jarak pemancar penerima : 1 km – 20 km
Lee Model
Lee formulated the path loss of beingLp[dB] = L0 + log d ; with L0 is path loss at d = 1 km
and is the path loss slope.Area L0 [dB] (dB/decade]
Free space 91.2 20
Open/rural area 90.4 43.5
Suburban area 104.3 38.4
New Ark 105.5 43.1
Philadelphia 112.8 36.8
New York City 117.5 48
Tokyo 128.1 30.5
Egli Model dan Blomquist-Laded Model EGLI MODELBased on Plane Earth Theoretical model with correction
factors
Lp [dB] = 120 + 40 log d – 20 log ht – 20 log hr +
Blomquist-Laded Model
Lp [dB] = Lfree space +{(Liplane earth – Lfree space)2 + (Ldiffraction)2}1/2
Alsebrook ModelFor flat areas Lp [dB] = Lplane earth +LB +
For hilly areas : Lp [dB] = Lfree space +{(Liplane earth – Lfree
space)2 + (Ldiffraction)2}1/2 + LB +
Ibrahim-Peterson Model
Lp [dB] = 40 log d – 20 log(hbhm) +