AU-KBC RESEARCH CENTRE

Measurement and Modelling of the channel medium for its attenuation and noise behavior is essential for the optimum design of communication links over it. This thesis addresses this problem for the 220/440 volts Low Tension outdoor segment of the Power Line System connecting the Distribution Transformer to the individual buildings where the electrical loads are situated. The measurements carried out in the MIT Campus and reported here are Broadband, covering upto 30 MHz, and have been done both in the Frequency Domain (Swept Frequency measurements), as well as in the Time Domain(Impulse Sounding measurements). Measured Attenuation and Noise behavior indicate a usable frequency range of typically 2-15 MHz over lenghts of 200-250 meters for sending end signal amplitudes of a few volts.  The measurement results have been used to build a Statistical Model for the Channel Impulse Response function along the lines commonly employed for the wireless channel medium.  The amplitude variations are found to fit a Log Normal distribution well, whereas the inter-arrival times are only poorly approximated by an Exponential Distribution.  Also developed in the present study are simulation models for the different types of Noise phenomenon observed on the powerlines such as the Background Noise, Narrow Band Noise, Impulse Noise and Harmonic Noise.  Along with the Impulse Response Model, this represents a Complete Modelling of the Outdoor LT environment that is presently not available in the published literature.  The model has been used to predict data rates that are likely to be realisable over the LT segment, and a value in the range of 1 to 2 Mbps seems possible over the campus network that was characterised in this study. This conclusion is also supported by the time domain measurement data generated in the present study.