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174 C h a p t e r T h r e e
+ +
- >= -74 dBm
- >= -81 dBm
- >= -88 dBm
+ + + - >= -91 dBm
FIGURE 3.3.3.3 Old versus new coverage plots. (A color version of this figure is available at
www.mhprofessional.comjiwpm. )
loss algorithm (top) and another from the predictions using the new diffraction loss
algorithm (bottom). The predicted coverage is much larger based on the new algorithm.
The original diffraction loss algorithm is more conservative, as we point out in Fig. 3.3.3.2.
3.3.4 Conclusion
It is important to have an accurate propagation model that deals with all the different
environments and limitations. This section presents several innovative and possible
revolutionary approaches in the Lee model that can better handle issues created by the
rough terrain sampling data. These enhancements enable the Lee model to be more
flexible and more accurate.
The model works only as long as the input data are accurate. In Chap. 6, we will
look into the input data that affect both urban areas and in-building propagation
modeling.
