Last week in the Digital Home newsletter, I linked to a news article about developments in the power-line networking arena. The article discussed developments in the IEEE P1901 working group that has been deadlocked for a couple of years in establishing a power-line home networking standard. Unfortunately I erred in my comments attributing the news to the G.hn networking group rather than the P1901 group -- where G.hn power-line technology is now one option. I should have know better in any event having followed these developments for years, but hurrying through a compressed Holiday week publishing schedule certainly contributed to my mistake. I'd like to correct the facts here, and add some additional commentary.
Here is the passage in question from the newsletter:
"Ironically, I wrote the projection on home networking. I didn't express a very favorable view on powerline networking -- at least when it comes to carrying multiple HD video streams. This week we get news that the G.hn group has finally settled their impasse on a powerline standard. But what did they really settle? The IEEE group, facing pressure from potential competitors, actually will define three separate PHY and MAC combinations. Rather than unifying the market and promoting growth, I see the news as hampering the technology. This confusion will only add to the technical challenges that powerline networks still face."
As I implied in the opening paragraph, it's the P1901 group that is purely focused on power-line networking that has decided to promulgate three different MAC and PHY combinations. And I still see that the option of using different technologies is a very bad thing. Indeed, the options in the 802.11n flavor of Wi-Fi is causing all kind of confusion and hampering widespread adoption. And power-line technology is not coming from a strong installed base such as the existing Wi-Fi user base.
I apologize to the G.hn group. That group is seeking to establish a cohesive set of network protocols for all forms of wired home networks -- those that operate over power-line, phone-line, and coax media. G.hn is being developed under the ITU (International Telecommunications Union). An advocacy organization called the HomeGrid Forum is handling promotion.
The P1901 group has identified G.hn power-line MAC and PHY technology as one of the three options that the IEEE group will standardize. The G.hn group, meanwhile, is continuing it's work. A recent announcement indicates that the standard is sufficiently defined for chip designs to get started.
Frankly I do have some questions as to what G.hn will bring to the game. In each of the wired categories, the ITU organization is facing existing standards that have been established either by other organizations or in the market. I know that some G.hn supporters don't have strong home networking plays in the market right now, so a new technology might provide them with an entry into the market.
There is not a fundamental need for phone, power, and coax networking technologies to share MAC and/or PHY layers. Ethernet provides a low-cost bridging option for wired and wireless networks. But perhaps a cohesive standard might yet allow HD video traffic to stream across the different wired media types more effectively.