TEAM FLY WIRELESS NETWORK DEPLOYMENTS phần 2 pdf

Cellular Network Deployment 17

6. CONCLUDING REMARKS

Cellular network deployment is partly science, partly engineering and

mostly art. This is due to the fact that RF propagation is “fuzzy” owing to

numerous RF barriers and scattering phenomena. Building codes vary from

place to place making it practically impossible to rely on software prediction

tools. Consequently we end up with drive test, collect data and fine-tune the

model. Even then, a margin of 8 to 10 dB in receive signal level is allowed

in the final design. These are the realities of RF design with respect to

cellular deployment. We have addressed many of these issues in this paper

namely, RF propagation, C/I, Frequency planning, cell site location,

intermod issues etc. and proposed possible solutions to enhance capacity and

performance. If my readers find this information useful, I shall be amply

rewarded.

18 Chapter 1

7. APPENDIX

A. Okumura-Hata Model

The Okumura-Hata model is based on experimental data collected from

various urban environments having approximately 15% high-rise buildings.

The path loss formula of the model is given by

where,

f = Frequency in MHz

d = Distance between the base station and the mobile(km)

Eq.(Al) may be expressed conveniently as

or more conveniently as

where

and

Eq.(A5) is plotted in Fig.Al as a function of base station antenna

height. It shows that in a typical urban environment the attenuation slope

varies between 3.5 and 4.