Powerline transmission uses various modulation methods in standardized frequency bands. The service providers use two methods: Narrowband and wideband modulation. Narrowband powerline( NB-PLC) provides a transmission speed of only 100 kbit/s, but has the advantage of being less susceptible to interference. Suitable modulation schemes include frequency shift keying( FSK), spread frequency shift keying( S-FSK), quadrature phase modulation( QPSK), differential code shift keying( DCSK) and, for wideband transmissions, orthogonal frequency division multiplexing( OFDM).
The Powerline communication bands
The Comité Européen de Normalisation Electrotechnique( CENELEC) has defined five communication bands for power distribution networks with different access requirements in the EN 50065 standard, the Cenelec bands. These five frequency bands are designated by the letters "A," "B," "C" and "D" and are used for narrowband powerline. Of the five standardized frequency bands, the bottom two are reserved for utilities, and the other three frequency bands are for communications services inside buildings: for in-house powerline networks or PowerLAN. The lowest, undesignated frequency band is between 3 kHz and 9 kHz. This is followed by the A frequency band between 9 kHz and 95 kHz, which is also reserved for utility data applications. For example, for transmitting meter readings from smartmeters to the communications center at the utility. The B frequency band from 95 kHz to 125 kHz, the C frequency band from 125 kHz to 140 kHz and the D frequency band from 140 kHz to 148.5 kHz are intended for private use inside buildings.
Under optimum conditions, data rates of up to 300 kbit/s can be achieved. For higher transmission speeds, frequencies between 1.6 MHz and 30 MHz are provided in Powerline. For indoor use in powerline networks, the frequency range is between 1.6 MHz and 13 MHz; for outdoor use, the frequency range is between 15 MHz and 30 MHz.
As far as the use of powerline in smart grids is concerned, there are two approaches here, Powerline Intelligent Metering Evolution( PRIME) and the G3-PLC protocol, for exchanging data between smart meters and the utility's Meter Data Management System( MDMS). The technologies mentioned operate in an extended frequency band of the Federal Communications Commission( FCC) in the range from 10 kHz to 490 kHz.