Exploring Joint Voltage and Impedance Modulation in Wired Networks

Conventionally, transmission of information in wired networks, as power line communication ones, is realized by modulating the voltage source at the transmitter side assuming a constant source impedance. If the impedance at the source is changed, this will induce a change of the line impedance at the receiver node. If such a change is measurable at the receiver node, then one may think to implement joint modulation of the voltage and impedance at the source, therefore transforming the wired network into two parallel communication channels. This paper investigates the principles behind this idea by deriving the input/output voltage/impedance relations, and possible transmitter/receiver architectures. A first architecture comprises only impedance modulation at the transmitter side with an impedance meter at the receiver side. Another architecture comprises joint voltage and impedance modulation with two possible receivers: a) a received voltage meter together with an impedance meter, or b) a voltage meter with a switched impedance receiver frontend. Numerical results are reported in terms of symbol error rate. They show that the approach has potentiality and opens the door to further investigations.