1. CHANNEL MODEL for INFOSTATIONS  Can this be the model for outdoors?  Andrej Domazetovic, WINLAB – February, 23

2. OBJECTIVE Assuming that the channel is Ricean and using the measurements by Feuerstein, Rappaport et. al. in San Francisco (2-ray model) try to develop the channel model proposal described as the behavior of Ricean K-factor with respect to transmitter-receiver distance.

3. INITIAL ASSUMPTIONS  Low transmitter antenna heights (3, 4 and 5m)  Receiver antenna height 1.7m  Clear line of sight path - no shadowing  Carrier frequency 5.1 GHz  Channel bandwidth 100 MHz  Omnidirectional antennas  No mobility (yet)

4. OUTLINE  Brief overview of standard 2-ray propagation model  Brief overview of Propagation over the earth  Closer look into propagation issues  Modified model  Link to Ricean K-factor  Real antenna pattern  Conclusions/Questions

5. Standard 2-ray propagation model Source: [] Rappaport - Wireless Communications Friis free space equation: Relation between power and electric field: Where: EIRP - effective isotropic radiated power, E - magnitude of radiating portion of electric field in the far field, R fs - free space intrinsic impedance and A e - antenna effective aperture

6. Standard 2-ray propagation model Source: [] Rappaport - Wireless Communications The electric field at receiver: assuming: large distance from the transmitter, Taylor series approximations, perfect ground reflection...

7. Standard 2-ray propagation model Source: [] Feuerstein, Rappaport et. al. - Path loss, Delay spread and Outage models as Functions of Antenna Height for Microcellular System Design - TVEH, Aug, 1994 In measurements performed in San Francisco, it was shown that 2-ray model is fairly good model for microcellular urban environment It was also shown that the path loss within first Fresnel zone clearance is purely due to spherical spreading of the wave front: decreases as d -2 and not d -4 (10m being the minimum T-R distance)

8. Standard 2-ray propagation model Source: [] Feuerstein, Rappaport et. al. - Path loss, Delay spread and Outage models as Functions of Antenna Height for Microcellular System Design - TVEH, Aug, 1994

9. Standard 2-ray propagation model Source: [] Feuerstein, Rappaport et. al. - Path loss, Delay spread and Outage models as Functions of Antenna Height for Microcellular System Design - TVEH, Aug, 1994 Fresnel zone clearance

10. Propagation over a plane earth Source: [] W.C. Jakes - Microwave Mobile Communications Propagation over smooth, conducting, flat earth Bullington: Where: first term - direct wave second term - reflected wave third term - surface wave rest - induction field and ground secondary effects  - phase difference between reflected and direct paths

11. ASSUMTIONS Source: [] Rappaport - Wireless Communications Friis free space equation: The formula is a valid predictor for P r for d which are in the far-field of the transmitting antenna - Fraunhofer region i.e. when inductive and electrostatic fields become negligible and only radiation field remains d f =2D 2 /, d f >>D and d f >> For f c = 5.1GHz and the antenna size D = 10cm d f =33.9cm, d f >>10cm and d f >>5.9cm If D (largest linear dimension of antenna) and f c increase, so does d f - attention must be paid

12. ASSUMTIONS First Fresnel zone distance: Antenna height:fd:for fc=5.1GHz 3m70.47m Mobile height:1.7m 4m118.29m 5m179.6m Since wavelength=5.9cm, the Bullington equation also holds (surface wave can be neglected) Source: [] Feuerstein, Rappaport et. al. - Path loss, Delay spread and Outage models as Functions of Antenna Height for Microcellular System Design - TVEH, Aug, 1994 [] W.C. Jakes - Microwave Mobile Communications

13. Ricean K-factor Source: [] Rappaport - Wireless Communications [] Steele - Mobile Radio Communications

14. Propagation Mechanisms Source: [] Rappaport - Wireless Communications

15. Propagation Mechanisms Source: [] Rappaport - Wireless Communications [] W.C. Jakes - Microwave Mobile Communications Reflection coefficient (Fresnel) depends on material properties, frequency, incident angle… Type of surface  (S/m)  Poor ground0.0014 Average ground0.00515 Good ground0.0225 Sea water581 Fresh water0.0181 Brick0.014.44 Limestone0.0287.51 Glass at 10 GHz0.0054 It is often related to relative permittivity value: (for lossy dielectric) - some energy absorbed If material is good conductor (f<  /  r  0 ) - not sensitive to f For lossy dielectrics: -  0,  r - const. with f but  may be sensitive

16. Propagation Mechanisms Source: [] Rappaport - Wireless Communications From Maxwell’s equations and Snell’s Law: When the first medium is free space and

17. Reflection coefficient

22. Ricean K-factor

26. Real antenna issues

27. Ricean K-factor - antenna

29. Close scatters – practical issue Assuming 100MHz bandwidth  200Msamples/second  1.5m path distance in order to detect another path wave

30. Some hints that look promising Source: [] IEEE Communication magazine, Jan 2001.

31. Conclusions/Questions 1.What do you think IMW or JFAI? 2.What to pursuit? - If this idea holds, how to prove it? - If not, should COSTs/ITUs/etc. be investigated better and picked one of those models? 2.If the channel is really that good  why OFDM? - Simplicity for Downlink (no PAPR headache, implementable on Winlab hardware) - DS-CDMA (no near-far, fully orthogonal code set, multiple access…)