ABSTRACT
The idea of using power lines also for communication purposes has already been around since the beginning of the last century [6,7]. It is now broadly referred to as power line communications (PLCs). The obvious advantage is the widespread availability of electrical infrastructure, so that theoretically, deployment costs are confined to connecting modems to the existing electrical grid. Following the nomenclature introduced in [8], power line technologies can be grouped into the following:
Ultra narrowband (UNB) technologies operating at very low data rate in the ultra- low-frequency band (ULF, 0.3–3 kHz) or in the upper part of the super-low-frequency band (SLF, 30–300 Hz). Examples of UNB-PLC are ripple carrier signalling (RCS) [6], the turtle system [9] and the more recent two-way automatic communications system (TWACS) [10,11]. Especially, automated meter reading (AMR) systems frequently used UNB-PLC technologies to gain access and in parts control over the energy meters within private homes. UNB-PLC systems are usually designed to communicate 254over long distances with their signals passing through low-voltage/medium- voltage transformers. This helps to keep the amount of required modems and repeaters to a minimum. Drawbacks are low data rates, for example, in the order of 0.001 bit/s (Turtle) and 2 bits per mains frequency cycle (TWACS) * . Additionally, these systems are sometimes limited to unidirectional communications.
Narrowband (NB) technologies operate in the very-low-, the low- and in parts of the medium-frequency (VLF/LF/MF) bands, which include the European Comité Européen de Normalisation Électrotechnique (CENELEC) bands (3–148.5 kHz), the US Federal Communications Commission (US FCC) band (10–490 kHz), the JP Association of Radio Industries and Businesses (ARIB) band (10–450 kHz) and the Chinese band (3–500 kHz). Within this class of NB-PLC, one may further subdivide into the following:
Low data rate (LDR), which refers to technologies capable of data rates of a few kbit/s. These technologies are usually based on single-carrier or spread-spectrum modulation. Typical examples of LDR NB-PLC technologies are devices conforming to the recommendations: ISO/IEC 14908-3 (LonWorks), ISO/IEC 14543-3-5 (KNX), CEA-600.31 (CEBus), IEC 61334-3-1, IEC 61334-5 (FSK and spread-FSK). They are backed by Standard Development Organisations (SDOs), precisely by the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). Additional non-SDO-based examples are Insteon, X10, HomePlug C&C, SITRED, Ariane Controls and BacNet. LDR NB-PLC technologies have also been referred to as distribution line carrier or power line carrier.
High data rate (HDR) refers to technologies capable of data rates ranging between tens of kbit/s and around 500 kbit/s. Today, HDR technologies are based on orthogonal frequency division multiplexing (OFDM) [12]. Typical examples of HDR NB-PLC technologies are those included in the family of approved International Telecommunications Union – Telecommunication Standardization Sector (ITU-T) NB-PLC Recommendations [13–15] and the ongoing Institute of Electrical and Electronics Engineers (IEEE) P1901.2 project [16]. Original non- SDO-based examples are the industry specifications G3-PLC and Powerline- Related Intelligent Metering Evolution (PRIME), which have recently become ITU-T Recommendations G.9903 and G.9904, respectively.
Broadband (BB) technologies operate in the medium-, high- or very-high-frequency
(MF/HF/VHF) bands (1.8–250 MHz) and have a physical layer (PHY) rate ranging from several Mbit/s to several hundred Mbit/s. Typical examples of BB-PLC technologies are devices conforming to TIA-1113 (HomePlug 1.0), IEEE 1901 and ITU-T G.hn (G. 9960–G. 9964) standards. Additional non-SDO-based examples are HomePlug AV2, HomePlug Green PHY, UPA Powermax and Gigle MediaXtreme. BB-PLC technologies devoted to ‘last mile’ and access applications have also sometimes been referred to as broadband over power lines (BPL).
