Presentation on theme: "Summary of Path Loss in Propagation"— Presentation transcript:
1 Summary of Path Loss in Propagation Narayan Mandayam
2 Understanding RF Propagation GoalsEstimate radio coverage areaEstimate link performanceEstimate network design parametersTransmitters and their locationTransmit powerAntenna typeHow many APs will be needed to cover IITK campus?
3 Interesting Scenarios At which locations will correct reception take place?
4 Antenna Basics 0 dBi 2.2 dBi 14 dBi High gain Dipole Isotropic directionalIsotropic0 dBi2.2 dBi14 dBi
5 Free Space Propagation Model Isotropic powerdensityPRdPTPower density alongthe direction ofmaximum radiationPower received byAntennaPredict received signalstrength when the transmitterand receiver have a clearline-of-sight path between themAlso knownas Friis freespace formula
6 Path Loss (relative measure) PRPtf is in MHzd is in KmPath Loss represents signal attenuation(measured on dB) between the effectivetransmitted power and the receive power(excluding antenna gains)
7 Path Loss (Example) PR Pt 59 20 (for d = 10) -20 (for d = 0.1) Assume that antennas are isotropic.Calculate receive power (in dBm) at free space distance of 100m from the antenna. What is PR at 10Km?PRPt50 W= 47 dBm-20 (for d = 0.1)5920 (for d = 10)