Philip Hunter /
05.09.2011
Originally featured on BroadcastEngineering.com
MoCA targets home networks in Europe

The Multimedia over Coax Alliance (MoCA) is training its sights on Europe despite giving up on hopes that coax cable will become the dominant in-home infrastructure for pay TV there. Concern over the ability of alternatives, principally WiFi and the HomePlug power line technology, to provide whole home network solutions for HD video is generating growing momentum behind the proven MoCA standard in some European countries.

So far, MoCA has been most successful in the United States because many homes are already wired with coaxial cable, which provides a ready platform for deployment of in-home networking for multiroom TV. This is not the case in most European countries, where there is resistance to installation of new wiring if there are acceptable wireless alternatives available. One option is WiFi, but most pay-TV operators do not regard this as being sufficiently reliable or robust enough to deliver multiroom pay TV in many homes, especially larger ones built with materials that impede radio signals.

Therefore, the HomePlug standard using electrical wiring, which by definition is already installed in rooms where TVs will be watched, has been gaining ground. However, MoCA argues that neither HomePlug nor WiFi is ready to serve as a backbone technology for the home network, especially for distribution of HDTV, while admitting that coaxial cable will not be universally deployed around homes.

MoCA President Charles Cerino conceded at last week’s ANGA Cable exhibition in Cologne, Germany, that no one technology would prevail in the home, and that WiFi would become increasingly dominant for distribution of video within single rooms.

“Hybrid networks will undoubtedly be the norm in European homes as existing WiFi networks are extended and enhanced with a MoCA-based in-home backbone that provides the additional bandwidth and reliability needed for today’s HD-rich services,” Cerino said.

MoCA’s strongest competition so far as a backbone technology has come from the HomePlug standard, which has been supported by many of the same industry players, including chip makers such as Broadcom. But, MoCA’s case has been strengthened by concerns over VHF emissions from power line networks. The frequencies used by power line can interfere with indoor reception of both FM and DAB devices, and the question is whether this is a serious problem or just an occasional blip that can be tolerated.

The concerns have been rumbling on for years, particularly within Europe where objections have also been raised in the past by amateur radio enthusiasts, as the European Union (EU) has strived for a common regulatory approach throughout the continent. The issue did seem to die down, but it has been reawakened as power line is deployed. This is partly because advancing technology and competition from MoCA has created pressure for higher data rates that can only be achieved in practice by going to still higher operating frequencies, increasing the overlap with the so-called Band II and Band III frequencies used for FM and DAB broadcasting. These are widely used for reception in the home, so any significant interference will potentially affect many people and threaten to derail power line.

While a variety of laboratory tests had shown that power line adaptors (PLAs), the devices via which equipment is plugged into mains wiring for communication, generated appreciable emissions in the VHF range, there had not been much research done over how this affected FM or DAB broadcasts in practice. This led the BBC in the UK to conduct its own study to investigate the interference potential of one specific PLA device.

The BBC has admitted that this is really only a preliminary study and that more research should be done but reported that interference did occur in two typical homes. One home was a semi-detached house in a suburban residential area well-served with FM and DAB signals. The second home was a detached bungalow (single-story dwelling) in a semi-rural residential area, also well-served with FM and DAB signals but farther away from broadcast transmitters than the first home.

In the case of FM reception, the impact of interference was found to depend on the signal strength, with severe problems in the case of services for which the home was at the edge of the coverage area. Similar reception problems were observed in the DAB band, where the existence of the digital cliff means that there is a critical combination of signal strength and interference beyond which reception suddenly disappears entirely.

This all led the BBC to the tentative conclusion that a significant number of homes could be affected by interference from PLA devices in both the DAB and FM bands. But, the BBC did emphasize that the effects might be different for PLA devices other than the one tested and that more work was needed.

Nonetheless, the results have dampened the previously growing momentum behind power line in Europe and are contributing to the increasingly bullish mood in the MoCA camp.



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