The HomePlug 1.0 limitation of 16 nodes can be overcome with a dash of proprietary technology supplies by systems such as those from Asoka and Telkonet. Proprietary technology also is required to deal with the three-phase power supplies found in some commercial buildings. One also must consider bandwidth, which is just too limited at HomePlug 1.0 best-case rates of 14 Mbps. Some proprietary systems use technology from Intellion, supporting raw signaling rates up to 85 Mbps, which comes very close to 100BaseT performance.
In-house BPL devices, which must comply with Part 15 of the FCC Rules for radiated emissions limits, have been available in stores for many years, although the HomePlug compatible devices are relatively recent.
Who Turned Off The Lights?
In-house BPL may be plug and play, but recess is over during power failures, or so it seems. That can be a big problem in a convergence scenario where we are running voice, data and video over an integrated network.
In the data and video domains, we are used to shutting down when the lights go out, but that's not the case in telecom. Dialtone is line powered and is protected by UPS (Uninterrupted Power Supply) battery systems and backup generators, so conventional phones still work when the lights go out. Some fancy phones, of course, require battery backup, and PBXs and key systems require UPS battery backup.