SISTEM KOMUNIKASI NIRKABEL Jati Fallat
Feb 09, 2016
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) +