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When analyzing the different PLC technologies available on the market today, one notices two fundamental and distinct design approaches. Certain well-known PLC technologies assume that the modulation and demodulation technique they implement is sufficient to guarantee the minimal threshold of reliability that the consumer demands. Such technologies would have us believe that they possess an ultra-sturdy Magic Bullet of sorts that will lay waste to the obstacles on its path. Such technologies give little importance to communication error management and do not implement Forward Error Correction (FEC).
The second, and in our opinion, more prudent and more realistic approach assumes that a PL communication channel is an extremely difficult medium and that communication errors will occur. Technologies conceived from that point of view actively manage communication errors and implement, for example, an FEC technique.
Granted, the Magic Bullet approach must also be implemented when designing a PLC technology, in that the chosen modulation/demodulation technique must be of the utmost sturdiness. For example, older PL techniques used an On-Off-Keying type amplitude modulation in which a silence, i.e., the absence of a carrier, represents the zero symbol. This type of modulation is, of course, sensitive to all noise sources in its band, even noise of low amplitude, since the presence of any noise changes a zero symbol (0) to a one symbol (1). It is now widely known that FSK modulation, for example, offers superior sturdiness.
Having chosen the modulation technique best suited to the communication medium, elementary caution and field-testing will then demonstrate that there are cases where communication errors exist and persist, despite the Magic Bullet. Unless consumers are willing to accept low reliability-an improbable position on the part of consumers-communication error management is, in our opinion, an absolute necessity, and all the more so considering that the PL medium is among the most challenging.
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