Page 200 - Integrated Wireless Propagation Models
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178    C h a p t e r  T h r e e


                  The diffraction losses L1 and L 2  are then estimated using

                                                                                (3.4.2.13)


                                                                                (3.4.2.14)

               The diffraction loss L0 at a mobile located at a distance d from the base station is


                                                                                (3.4.2.15)
               where

                                                                                (3.4.2.16)


               and
                                                                                (3.4.2.17)
                                             o
                                            L = Afo + L - d m d
                                                    z
                                                        z
               where an empirical clutter factor A1o is determined as
                                                                                (3.4.2.18)

               where Afi, is given by


                                                                                (3.4.2.19)
               and o(d ) is given by
                     L5

                                    o(d ) = 0.78h (d)exp{-O.S[M(d)]+}  m        (3.4.2.20)
                                      L5
               The Langley-Rice model has used the empirical formulas based on the measured
               data to predict the path loss. This model has been widely used in US government
               projects.


          3.5   Summary
               This chapter focuses on macrocell modeling. Although two models were discussed, the
               key is to understand those approaches that different models take to solve the common
               problems. The input from measured data should be carefully examined before use. The
               characteristics of the mobile environment and the algorithms from the different models
               that deal with these issues are discussed.
                  The Lee model has been around for a long time. The earlier version of Lee model
               has been used by AT&T and named the ADMS planning tool.33 The later version has
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