Mobile radio propagation models are derived using empirical and analytical methods to account for all known and unknown propagation factors. Signal strength must be strong enough for quality but not too strong to cause interference. Fading can disrupt signals and cause errors. Path loss models predict received signal level as a function of distance and are used to estimate signal-to-noise ratio. Path loss includes propagation, absorption, diffraction, and other losses. Large-scale models describe mean path loss over hundreds of meters while small-scale models characterize rapid fluctuations over small distances.

1. MOBILE RADIO PROPAGATION UNIT 2

7. Path Loss Exponents

8. Path Loss

10. Large-Scale & Small-Scale Fading

18. EIRP Effective Isotropic Radiated Power EIRP = Pt Gt which represents the maximum radiated power available from a transmitter in the direction of maximum antenna gain, as compared to an isotropic radiator .

19. ERP In practice, effective radiated power (ERP) is used to denote the maximum radiated power as compared to a half-wave dipole antenna.

20. Propagation Illustration received signal T s  max transmitted signal

23. Multipath Propagation

28. Diffraction Geometry

30. Graphical representation

31. Lee’s Approximate

43. Applications The probability that the received signal level will exceed a certain value γ can be calculated from the cumulative density function as Can be used to determine the percentage of coverage area in cellular systems .

47. UNIT - 2 THE END