Power Line Communication and Transmission Speed

Power Line Communication (PLC) allows data to be sent over existing power lines. This means that commands can be read and executed using only electrical wiring connected to the energy meter.
It is the most cost-effective method for AMI-solutions. Communication with domestic meters, first only for reading purpose, became popular in the late 90s of the last century. Now you can find a bunch of different principles.
Since the majority of PLC-systems can not transmit data to the primary side of transformers, we consider here only the low-voltage side.

Transmission Rates

Speed	< 10 kbps	10 kbps to 1 Mbps	> 1 Mbps
Mod.	PSK, BPSK, S-FSK, QAM	PSK, OFDM	PSK, OFDM
Standard	IEC 61334, ANSI 709.1	G3-PLC, PRIME	IEEE 1901
Frequency range	≤ 500 kHz	≤ 500 kHz	> 500 kHz
Used for	meter control via AMI	meter control via AMI	Broadband, home network

Modulation Methods

We have a wide variety of modulations when using power-line communication.

Frequency Shift Keying (FSK)
Spread Frequency Shift Keying (S-FSK)
Phase Shift Keying (PSK)
Quadrature Amplitude Modulation (QAM)
Binary Phase Shift Keying (BPSK)
Orthogonal Frequency Division Multiplexing (OFDM)

The actual trend is going to OFDM. This modulation offers the highest transmission rates. Back draw, it needs an additional DSP (digital signal processor). The microcontroller can't deliver the processing speed.

In addition, we can now find different particular proprietary standards:

Standard	Mod.	Frequency	Speed
G3-PLC	OFDM	36 kHz to 96.6 kHz	5.6 kbps to 45 kbps
PRIME	OFDM	42 kHz to 89 kHz	21.4 kbps to 128.6 kbps
IEEE 1901	OFDM	5 kHz to 500 kHz	still not specified
ANSI 709.1	BPSK	86 kHz and 131 kHz	3.6 kbps to 5.4 kbps
IEC 61334	S-FSK	3 kHz to 95 kHz	2.4 kbps

kbps = kilo bit per second

Allowed Frequency Bands by Regions

Different regions of the world have different frequency bands allocated to narrowband PLC for usage with smart meters.

Region	Regulatory body	Frequency
Europe	CENELEC	3 kHz to 95 kHz
China	EPRI	3 kHz to 500 kHz
USA	FCC	10 kHz to 490 kHz
Japan	ARIB	10 kHz to 450 kHz

CENELEC – European Committee for Electrotechnical Standardization
EPRI – Electric Power Research Institute
FCC – Federal Communications Commission
ARIB – Association of Radio Industries & Businesses

Conclusion

The fastest data communication between energy meter and data-concentrator unit can be achieved with OFDM modulation. Nevertheless, the communication success rate is depending on the topology and grid infrastructure.
So for certain regions, a slower communication speed can lead to higher AMI-system performance.

Thank you for reading.

Editor's note: This article was originally published in June 2021 and has been updated for comprehensiveness.