1 / 28

Path Loss Model in Mobile Cellular Network

Path Loss Model in Mobile Cellular Network. Walfish-Ikegami Model. Okumura-Hata Model. Lee’s Prediction Model. Okumura-Hata Model. Microcellular areas span a few Kms. Okumura in 1968 drew some path-loss curve in the range of 100MHz to 1920 MHz

macha
Télécharger la présentation

Path Loss Model in Mobile Cellular Network

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Path Loss Model in Mobile Cellular Network

  2. Walfish-Ikegami Model Okumura-Hata Model Lee’s Prediction Model

  3. Okumura-Hata Model • Microcellular areas span a few Kms. • Okumura in 1968 drew some path-loss curve in the range of 100MHz to 1920 MHz • Masaharu Hata developed empirical path-loss model based on measurement of Okumura known as Okumura-Hata model. • Here separation between BS and MS is greater that 1Km.

  4. Empirical formulation of data provided by the Okumura model and is valid for frequencies in the range 150MHz-1500MHz For large city, For small and medium city,

  5. For suburban and open rural area, The model is suitable for a distance above 1 Km. The model does not support path specific correction Coverage Frequency: 150 MHz to 1500 MHz Mobile Station Antenna Height: between 1 m and 10 m Base station Antenna Height: between 30 m and 200 m Link distance: between 1 km and 20 km.

  6. Example Frequency: 900MHz Propagation Environment: Urban BS antenna height: 50m MS antenna height: 1.5m Cell radius: 5Km Ans. a(hm) =0.001dB = 177.7077dB LSuburban = 167.7651dB LRural =149.2012dB fc=900;% Carrier frequency MHz hBS=50;%BS antenna height m hMS=1.5;%MS antenna height m d=5;% Distance Km a_hMS=3.2*((log10(11.75*hMS))^2)-4.97; LUrban = 69.55+26.16*log10(fc)-13.82*(log10(hBS))+(44.9-6.55*log10(hBS))*log(d)-a_hMS; LSuburban= LUrban-2*(log10(fc/28))^2-5.4; LRural= LUrban-4.78*(log10(fc))^2+18.33*log10(fc)-40.94;

  7. %Code by Imdad fc=900;% Carrier frequency MHz hBS=100;%BS antenna height m hMS=2;%MS antenna height m d=1.1:0.4:6;% Distance Km a_hMS=3.2*((log10(11.75*hMS))^2)-4.97; LUrban = 69.55+26.16*log10(fc)-13.82*(log10(hBS))+(44.9-6.55*log10(hBS))*log(d)-a_hMS; LSuburban= LUrban-2*(log10(fc/28))^2-5.4; LRural= LUrban-4.78*(log10(fc))^2+18.33*log10(fc)-40.94; plot(d,LUrban, 'r>:', d, LSuburban, 'ms:', d, LRural, 'bd:') legend('Urban', 'Suburban', 'Rural') xlabel('Distance in Km') ylabel('Path loss in dB') title('Okumura-Hata Model') grid on

  8. Walfish-Ikegami Model

  9. The Walfish–Ikegami model is an empirical propagation model for an urban area, which is especially applicable for micro cells but can also be used for macro cells. Model Parameters: The mean value for street widths (w) is given in metres and the road orientation angle (θ or φ) in degrees. The mean value for building heights (hroof) is an average over the calculation area and is given in metres. The mean value for building separation (b) is calculated from the centre of one building to the centre of another building and is also given in metres.

  10. Walfish–Ikegami model is suitable for frequencies 800MHz to 2000 MHz where distance can be very small like 200m. Range of BS antenna height 4 to 50m and that of MS is 1 to 3m. Distance in the range of 20m to 5Km.

  11. For LOS case, Lm(db) = 42.6 +26log(d) + 20log(fc); d ≥ 20m For NLOS case, we have to consider, Hroof = Height of roof-top ΔhBS = hBS - hroof ΔhMS = hroof - hMS w: width of street in meter b: Building separation in meter along the radio path φ: Road orientation w.r.t. the direction of radio propagation in degrees incident angle relative to the street).

  12. NLOS path loss composed of three terms, LP(DB) = L0 + Lrts + Lmsd The model works best for the BS much taller than the surrounding buildings. L0: Free space path loss = 32.4 + 20log(d) + 20log(fc) Lrts: roof-street diffraction and scatter loss = -16.9 -10log(w) + 10log(fc) + 20log(Δhm) + Lori Lori is the street orientation loss:

  13. Lmsd = multiscreen diffraction loss = Lbsh+ Ka + Kdlog(d) + Kflog(fc) - 9log(b)

  14. The parameter Ka increases the path loss in case the BTS is below the rooftop. The parameters Kd and Kf are for adjusting the correction between the distance and frequency with multiscreen diffraction.

  15. Example:1 Find cell radius for the following parameters. fc =1800MHz Street width (w) = 20m Spacing between buildings (b) = 40m Average roof height (hroof) = 40m Mobile antenna height (hm) = 2m BS antenna height (hb) = 40m Street orientation φ = 900 Allowable path loss =140dB

  16. ΔhBS = hBS – hroof = 40 – 40 = 0 ΔhMS = hroof – hMS = 40 – 2 = 38m Orientation loss, Lori = 4 - 0.114(φ - 55) = 0.001 Lbsh = -18log(11) + (hBS - hroof) = -18.75dB Ka = 54 Kf = 4 + 1.5(fc/925 -1) = 5.42 The roof street diffraction and scatter loss, Lrts = -16.9 -10log(w) + 10log(fc) + 20log(ΔhMS) + Lori = -16.9 -10log(20) + 10log(1800) + 20log(38) + 0.001 =34.25dB

  17. Free space path loss, L0 = 32.4 + 20log(r) + 20log(fc) = 97.5 + 20log(r) dB Multi screen diffraction loss, Lmsd = Lbsh+ Ka+ Kflog(fc) - 9log(b) = 38.47 + 18log(r) dB Allowable path loss, 140 = L0 + Lmsd + Lrts= 97.5 + 20log(r) + 38.47 +18log(r) + 34.25 Or, 38log(r) = -30.23 Or, r = 0.16Km = 160m

  18. Lee’s Path Loss Model • Lee’s model can be used to predict area-to-area path loss. The • model consists of two parts, • Path loss prediction for a specified set of conditions • Adjustment factors for a set of conditions different from the specified one

  19. Lee’s Prediction Model Pr r ro = 1mil = 1,6 km Pro • The model requires two parameters: • Power at 1mile interception Pro in dB. • Path loss exponent γ Received power, In (dB), n is a constant between 2 and 3 depend on geographical location and operating frequency is an adjustment factor for different set of conditions

  20. Specified conditions Carrier frequency, fc = 900MHz BS antenna height = 30.48 m (100ft) MS power at the antenna =10W BS antenna gain = 6dB above dipole gain MS antenna gain = 0dB above dipole gain MS antenna height = 3 m (10ft)

  21. Lee’s Prediction Model α0 in dB, ao = a1 .a2 . a3 . a4 . a5

  22. There is a 3dB gain received from an actual 4-dB gain antenna at the mobile unit in a suburban area and less than 1-dB gain received from the same antenna in an urban area fro adjusting α5

  23. Lee’s Prediction Model Correction factor to determine v in a2 v = 2, for new mobile-unit antenna height > 10 m v = 1,for new mobile-unit antenna height < 3 m Parameters in Lee’s path loss model

  24. For suburban area, Pr = -61.7-38.4log(r) - nlog(f/900) + α0 α0 = 20log(hBS) +10log(Pt) + gBS + gMS +10log(hMS) - 64 Here transmit power in Watt, height of antenna in feet and gain of antenna in dB

  25. %Lee's path loss model v=3; Pt=55;% in watts n=2; gBS=12; hBS=200; hMS=12; f0=900; %in MHz f=1200; alpha1= (hBS/30.48)^2; alpha2= (hMS/10)^v; alpha3= (Pt/10); alpha4= (gBS/4); alpha5= (1/1); d=1:0.4:6;

  26. gama=3.84;%Suburban area r0=1.609; % in Km Pr0= -61.7; %in dB for Suburban area Pr1=Pr0-gama*10*log10(d/r0)-n*10*log10(f/f0)+(10*log10(alpha1)+10*log10(alpha2)+ 10*log10(alpha3)+ 10*log10(alpha4)+ 10*log10(alpha5)); Loss1=10*log10(Pt)-Pr1; gama=3.05;%urban area ToKyo Pr0= -84; %in dB for urban area ToKyo Pr2=Pr0-gama*10*log10(d/r0)-n*10*log10(f/f0)+(10*log10(alpha1)+10*log10(alpha2)+ 10*log10(alpha3)+ 10*log10(alpha4)+ 10*log10(alpha5)); Loss2=10*log10(Pt)-Pr2; gama=4.35;%for open area Pr0= -49; %in dB for open area Pr3=Pr0-gama*10*log10(d/r0)-n*10*log10(f/f0)+(10*log10(alpha1)+10*log10(alpha2)+ 10*log10(alpha3)+ 10*log10(alpha4)+ 10*log10(alpha5)); Loss3=10*log10(Pt)-Pr3; plot(d,Loss1, 'r>:', d, Loss2, 'ms:', d, Loss3, 'bd:') legend('Suburban', 'Urban', 'Rural or Open area') xlabel('Distance in Km') ylabel('Path loss in dB') title('Lee’s Model') grid on

More Related