Tham khảo tài liệu 'advanced transmission techniques in wimax part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 166 Advanced Transmission Techniques in WiMAX Fig. 1. Fragment of the city region Numerals indicate segments of streets. For example the designation 1-2 should be read the second part of the first street. BS radiates waves of spherical front WSF . Further we shall consider based upon the Huygens principle that in the radial streets denoted by numbers 1-4 in Fig. 1 the radiated spherical wave is transformed into a series of waves with the locally flat front LFF . A further approach is to use the following approximations. The street is represented by several continuous homogeneous and smooth surfaces which form the guide system with losses. Straight-line segment of length l of this guide system is replaced by an equivalent two-wire line segment. Wave resistance and wave factor p of this line are equal to the characteristic impedance and wave ratio of free space. Equivalence should be determined by equality of power transferred to the real and equivalent systems . largest attenuation. The attenuation is determined by losses in RWP calculated by RWP LAN-MAN model Strelnitskiy 2008 phase - by value pl . As a result segments of the line are easily represented by matrices of the quadripole scattering S Gostev 1997 . The properties of these segments are as follows all lines have equivalent impedance equal to Z0 because they spread a wave of T-type street intersection for example 2 3 c 5 6 on Fig. 1 is a set of included equivalent line segments and in terms of circuit theory it is a power distribution system PDS . CPM with n equal divisions of channels described by the matrix S of ideal multipoles together with segments of lines with losses constitute a particular scheme the calculation of which can be performed by cyclic algorithm. As a result the considered scheme is equivalent to a multipole Gostev 1997 Fig. 2 which can be used to determine the amplitude of the field at any point of WCAB. Performance Analysis and Noise Immunity WiMax Radio Channel 167 Fig. 2. .