The announcement this week from Homeplug was all a bit ‘Yada, Yada’ pointing out more or less what we knew already, and hiding the meat of the new Homeplug AV2 technology away from prying eyes. It has always meant to be a Gigabit class version coming next at the PHY level delivering perhaps 600 Mbps in real terms. But just how we are going to get there remains mostly a mystery.
Homeplug AV2 is being corralled to come onstream at around the same time as MoCA 2.0 so that the two technologies can be lined up to work side by side around the home, and at comparable speeds.
What the HomePlug Powerline Alliance did say this week was that it has had a number of decisions about the technology that it will deploy and that it is still on track to deliver the standard this year and products sometime next.
Those decisions are that the new Homeplug AV2 will use MIMO, which given that there are no antenna involved here means that the data signal will be propagated from multiple points on the power line, and picked up from multiple points, and a comparison scheme will be put in place to obtain diversity benefits. A new transmission coding scheme will be used and there will be a slightly more efficient MAC. The notice says that it will also use increased spectrum, up an order of magnitude beyond that used by current power technology.
Well that’s always the obvious answer and the existing Homeplug AV system uses between 2 and 28 MHz spectrum on power cables, and the FCC has always imposed a frequency limit of 1.8 to 30MHz ‘ so we can’t quite see how another few hundred MHz can be made available without a complete change at the FCC. Perhaps it just means that technology has moved on enough to create more OFDM channels in the same spectrum, which is more likely. The spectrum block was originally put in place partly due to interference on the power cable by electricity use, but also to prevent interference escaping from the power cables and interfering with other spectrum. Homeplug will need to clarify this. If it really means more spectrum, then we wonder if perhaps this is shooting itself in the foot, or that an approving FCC has already given Homeplug the nod, due to the Obama administration love of all things broadband.
The other change will be to extend coverage be repeating and routing technology in networks of three or more nodes, the announcement said.
The AV2 specification will be interoperable with the current HomePlug AV and future HomePlug Green PHY and IEEE 1901 products and Homeplug reckons these throughput improvements will mean it can cope with multiple streams of 1080p HD video, as well as the emerging 4K HD. It should easily manage that in compressed formats if it reaches 600 Mbps, but not in the uncompressed formats that some candidates for in-home digital TV signals have been talking about.
The HomePlug Technical Working Group said it made all of its technology selections based on field testing and channel characterization, technical evaluations, simulations and experience with the widely deployed base of HomePlug AV products, it says.
Rob Ranck, president of the HomePlug Powerline Alliance, said, ‘Consumers are increasingly interested in the large, growing volumes of video, gaming and other media content available via the Internet, and they need an easy way to connect entertainment devices that allow them to move multiple streams of content to any room in the home. HomePlug AV has been the powerline technology of choice, and AV2 provides an aggressive migration path to support greater network capacity and distribution of ultra-high quality content throughout the home.’
The combination of MoCA and Homeplug will have to stand up to a considerable number of competing wired and wireless competition for the next generation choice in digital home networking including Wireless HD, WiGig, G.hn and HDBase T, not to mention wired HPNA and plain old WiFi.