Electronic Design

Powerline Communication Standards Continue To Struggle

Will any of the many standards emerge as the single winner? Probably not.

Home networking is an interesting consumer electronics niche that now affects most homeowners, especially if they have a PC with high-speed Internet access or the need to interconnect multiple TV sets, DVD players, digital video recorders (DVRs), and the like. The clear home networking champion, at least for PC Internet access, is Wi-Fi. It’s easy to implement and usually covers the whole house, allowing multiple PCs and laptops to use the high-speed DSL or cable service. The lack of wires makes it a joy.

Yet other home networking solutions out there also focus on the multimedia aspects of consumer electronics. The Mulitmedia over Coax Alliance (MoCA) uses the installed cable TV coax in your walls to interconnect TV sets and other multimedia devices without adding any extra wires. Home PNA is another option, using the installed telephone wiring (ADSL/VDSL) and/or coax. Then there’s the powerline networking option.

This solution puts orthogonal frequency-division multiplexing (OFDM) on the ac powerline for high-speed data transfers over the installed power wiring. Again, there are no new wires. The standard ac outlets are your network connections. That has to be as convenient as wireless, since every room or area in your home probably has multiple ac outlets. Yet the powerline networking segment of home networking is in a muddle and not doing as well as it could.

Standards Muddle

There are four or five (depending how you consider them) competing powerline home networking standards—the HomePlug AV standard, the High Definition Power Line Communications (HD-PLC) standard, the Universal Powerline Association standard, the IEEE P1901 standard, and the new ITU G.9960 standard, also known as G.hn. The ITU standard is still in development, so there’s no supporting silicon yet. However, all the other standards have semiconductor company support as well as end products in the market.

It’s hard to say who’s making any money in this niche, but my guess is that no one standard has the critical mass that would make it overwhelm the others or become the single owner of the home networking space. The closest one to such a goal is probably HomePlug AV, as the HomePlug Powerline Alliance has been around the longest (2000) and has more members (70+).

But there are so many other competitors in this arena. It is just like so many other standards battles in the communications field—lots of technologies, ideas, patents, and other intellectual property and a major stubbornness that reflects that ever present “not invented here” or “mine is better than yours” attitudes. It’s business as usual, but multiple standards lead to marketplace segmentation, customer confusion, and certain interoperability of products.

The result is that this technology doesn’t live up to its potential and gives away the business to other more clear-cut single standards like wireless, MoCA, or HomePNA, all of which are already pretty well entrenched. Yet isn’t multiple standards the American way? We live with the effects of competition every day, though the outcome isn’t always optimum for the competitors. But getting the competing standards bodies to come together and compromise is a real challenge.

The IEEE P1901 effort was an attempt at compromise to bring the HomePlug AV and HD-PLC technologies together. HomePlug AV uses fast Fourier transform (FFT) OFDM, while HD-PLC, invented by Panasonic, uses wavelet OFDM. Of course, they’re incompatible. However, the P1901 standard has dual physical layers (PHYs) and co-existence features. It doesn’t seem wise for anyone to make a chip that will do both, but who knows what someone will do with it? I heard that the P1901 standard will add some conditions to accommodate the new G.hn standard, whatever that means.

As for the ITU standard, I have been unable to find out why this whole effort got started. With so many existing standards, why take a start-from-scratch approach? Who will support it after others have invested fortunes in silicon design and marketing? What were they thinking? Is the potential size of the powerline home networking market big enough to support one more competitor and warrant all much investment? With the consumer market as a target, it may be.

The HomePlug View

HomePlug president Rob Ranck said the G.hn effort further fractures the industry by introducing one more standard that isn’t compatible with the installed base. Further, Ranck said the forthcoming higher-speed HomePlug AV2 standard would be available before G.hn and backward compatible with AV and P1901 products. It is estimated that there will be about 60 million HomePlug and P1901 devices installed before G.hn products hit the market.

While HomePlug feels that G.hn may be similar to HomePlug AV, there will be enough differences to make the two incompatible. One good example is HomePlug AV’s use of turbo-code forward error correction (FEC), while G.hn is expected to use low-density parity check (LDPC) for FEC. There are also differences in the protocol preamble. HomePlug is hopeful those differences can be worked out.

One interesting development with HomePlug is its work with the ZigBee Alliance to create a Smart Energy standard for a home-area network (HAN) that can help utilities minimize power usage and save homeowners considerable energy dollars. The powerline and wireless components complement one another to cover large homes and multi-dwelling units. Consumers can achieve considerable savings by monitoring and reporting energy usage.

What Would You Do?

Let’s say you’re an engineer with the responsibility to select a powerline communications technology to make a product. It isn’t an easy choice. I would look at all the candidates and undergo at least a minimal comparison. But for practical reasons, I would select the standard with the best chip availability, support from an organization like an alliance, market penetration, and future roadmap or potential. I’m sure other non-engineering issues will influence that decision like various partnerships, customer relationships, and personal and political reasons.

Given an engineering-only approach, I would probably go with HomePlug AV. It appears to meet all the criteria I mentioned above. It has powerline communication (PLC) pioneer Intellon for chips as well as Giggle. It is also part of the IEEE P1901 standard. It has good support from an alliance with more than 70 members. Furthermore, it has a road map to the next generation, called AV2, which boosts the data rate to more than 200 Mbits/s.

I couldn’t check market penetration, but I bet there are more HomePlug-compatible products out there than any others. HomePlug indicated that HP had more than 27 million compatible products out there already. Anyway, that’s what I would do based on common sense alone. As comedian Dennis Miller used to say, “That’s just my opinion. I could be wrong.”

Each situation is unique, and in many ways, it’s good to have so many competing options. My big question, though, is who on earth wants to wait another few years until the ITU standard is complete. Will it be better or more compelling that what’s already on the books and roadmaps? It doesn’t make sense to have another standard, even if it promises to incorporate compatibility measures with existing standards. Any new chip that supports multiple technologies is going to be bigger, more complex, and, more importantly, more expensive.

More On G.hn

To be fair, I spoke with the folks at the HomeGrid Forum, the organization that supports and promotes the G.hn standard. Their stated objectives are solid and sound promising. Basically, they want to deliver a single unified technology for the wired home network that addresses key issues for service providers, electronics manufacturers, and consumers. They’re trying to foster a single PHY/media access controller (MAC) that can be used over any wire, coax, phone line, or powerline.

The promise is a 400-Mbit/s data rate with aggregate of 250-Mbit/s throughput, with a 1-Gbit/s rate on the roadmap. The group’s goal is to get products integrated into consumer electronics as well as set-top boxes (STBs), residential gateways, and other customer premises equipment (CPE). It’s hard to fault the goals, for sure. The HomeGrid Forum isn’t just targeting the powerline space but other home networking technologies like MoCA and HomePNA as well. The group has more than 35 members, and many of them already support other standards. I guess you have to cover all of the bases in this field in case it takes off.

What will happen to the other standards once this one is finally approved and chips are available? Will everyone rush to it and abandon the older standards? That’s hard to believe. And not only will all the other powerline standards be affected, but G.hn should have an effect on those other wired home networking standards like MoCA and HomePNA as well. Is G.hn too little too late? Will it further split the industry into one more camp? Or will it finally bring everyone together?

What’s Next?

I don’t know how this will all play out. It is certainly one of the more interesting communications standards fights I have seen in a while. All the existing standards organizations have stated a willingness to work with and support the G.hn effort. They hope to influence the outcome or get in on any co-existence or interoperability efforts. Will that lead to a final standard designed by a committee and so overly complex it accommodates everyone? We’ll have to keep an eye on the developments. I’ll report on them as they happen.

For More Information

Home Grid Forum

www.homegridforum.com

HomePlug Powerline Alliance

www.homeplug.org

HomePNA

www.homepna.org

HD-PLC Alliance

www.hd-plc.org

Universal Powerline Association

www.upaplc.org

Related Articles

Supporting The Gh.n Wireless Networking Standard

Can Home Networking Find A Happy Medium?

Smart Grid, C&C Requirements Issued For Powerline

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