Broadband Powerline Communications Networks Design phần 4

Powerline thông tin liên lạc cũng có thể được áp dụng trong các tòa nhà hoặc nhà cửa, nơi một cài đặt bên trong điện được sử dụng cho việc thực hiện các mạng PLC trong nhà. Băng thông rộng Powerline Mạng Truyền | 72 Broadband Powerline Communications Networks Figure Spectral density model for the generalized background noise and build therefore frequency bundles that are usually approximated by a narrowband occupation. Therefore for its modeling this noise will be seen as a narrowband noise with very low psd. The power density of the colored background noise is time-averaged for the modeling by NCBN f . The time-dependence characteristic of this noise can be modeled independently with the knowledge of the standard deviation Beny03 . Therefore the psd of the generalized background noise can be written under the following form NGBN f Ncbn f Nnnơ B Ngbn T Ncbn f NNN f k 1 where NCBN f is the psd of the colored background noise NNN f the psd of the narrowband noise and A Nx f is the psd of the subcomponent k generated by the interferer k of the narrowband noise. For the model of the colored background noise psd the measurements have shown that a first-order exponential function is more adequate as formulated by Eq. Beny03 . f Ncbn f No Ni e f1 with N0 the constant noise density N1 and f1 are the parameters of the exponential function and the unit of the psd is dB i V Hz1 2. Through different investigations and measurements of noise in residential and industrial environments it was possible to find out approximations for the parameters of this model and the psd of the colored background noise can be described by Eqs. and for residential and industrial environments respectively Phil00 - f MHz NBN f -35 35 e 3 6 for residential environments and f MH NBN f -33 40 e 8 6 for industrial environments PLC Network Characteristics 73 For the approximation of the narrowband noise interferers the parametric Gaussian function is used whose main advantages are the few parameters required for specifying the model. Furthermore the parameters can be individually found out from the measurements which have shown only a small variance Beny03 f f0 k 2 NNN

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