Analysis of In-vehicle Power Line Channel Response

Power Line Communications (PLC) technology in automobiles consists in using the power lines inside the vehicle as an information transmission medium. When the engine of a car is in operation, the alternator is the element that supplies the electric energy. The periodic movement of the rotor inside the alternator causes frequency of the generated AC signal and the impedance of the alternator to depend on the regime of the engine. This time variation of the impedance may lead to a periodically time-varying behavior of the channel response. The objective of this paper is to evaluate the magnitude of these periodical variations and to determine whether a linear time-invariant (LTI) channel model suffices or a linear periodically time-varying (LPTV) one is needed. The analysis has been accomplished on a set of measurements carried out at different access points inside a vehicle.