First Mile Access Networks and Enabling Technologies

Modulation Requirements in PLC

To transmit a signal over a power line, it is imperative to modulate the signal onto a carrier frequency for two reasons. First, as explained in Chapter 4, “Data Wireless Communication,” by modulating a baseband signal onto a higher-frequency carrier, attenuation is substantially reduced. Second, to make good use of the frequency spectrums power lines provide, one must multiplex as many channels as possible in the same power line. This means frequency-division multiplexing (FDM) of multiple frequencies on the same power line. This also serves as an aid for demodulation. If a power-line network has three houses connected, and if each is trying to demodulate the same signal, for example, multiple issues must be dealt ...