{"id":196,"date":"2011-11-22T23:32:54","date_gmt":"2011-11-22T23:32:54","guid":{"rendered":"http:\/\/microsoftgeek.com\/?p=196"},"modified":"2011-11-22T23:32:54","modified_gmt":"2011-11-22T23:32:54","slug":"powerline-faq","status":"publish","type":"post","link":"https:\/\/microsoftgeek.com\/?p=196","title":{"rendered":"Powerline FAQ"},"content":{"rendered":"

\"SmallNetBuilder's<\/p>\n

Our Essential Wireless FAQ<\/a> gets a lot of regular use. So we figured why not try the same thing for powerline networking?<\/p>\n

<\/ins><\/ins><\/div>\n

If you don’t see your question here, let me know<\/a>. I can put it in the next FAQ article or in an update to this one.<\/p>\n

<\/a>1. Are all powerline adapters the same?<\/h3>\n

No. Powerline networking suffered through a contentious standards battle that dragged on way too long and hurt powerline’s adoption as a mainstream consumer networking technology<\/a>. Things are much better today because there is finally an IEEE standard (IEEE P1901) and past battles are over.<\/p>\n

Table 1 summarizes the past and present powerline technologies<\/a> and shows which are still available today.<\/p>\n\n\n\n\n\n\n\n\n
Product Technology<\/th>\n Status<\/th>\n<\/tr>\n
HomePlug 1.0<\/th>\nDiscontinued<\/td>\n<\/tr>\n
HomePlug 1.0 w\/ Turbo<\/th>\nDiscontinued<\/td>\n<\/tr>\n
HomePlug AV<\/th>\nShipping<\/strong><\/td>\n<\/tr>\n
DS2 \/ UPA<\/th>\nDiscontinued<\/td>\n<\/tr>\n
HomePlug AV 500<\/th>\nShipping<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Table 1: Powerline Technologies<\/h6>\n

All of today’s “200 Mbps” powerline adapters are based on Qualcomm Atheros<\/strong> technology (acquired with Atheros’ purchase of Intellon<\/a> in fall 2009), which is HomePlug AV compliant. So all should work together.<\/p>\n

Differences in firmware revision and design, however, can result in some adapters having better performance<\/a> than others. You can get an idea of the performance difference in our HomePlug AV Adapter Roundup<\/a> and by reading other HomePlug product reviews.<\/p>\n

<\/a>2. What speed can I expect from a powerline connection?<\/h3>\n

Just as with wireless products, the number on the powerline product box indicates the maxium link (raw data) rate, not the actual throughput delivered. HomePlug AV products all have a maximum 200 Mbps<\/strong> link rate, with typical actual throughput around 40 Mbps. Table 2 powerline technologies and their maximum link rate and actual tested throughput.<\/p>\n\n\n\n\n\n\n\n\n
Product Technology<\/th>\n Maximum Link Rate
\n(Mbps)<\/th>\n		Typical Actual Throughput
\n(Mbps)<\/th>\n<\/tr>\n
HomePlug 1.0<\/th>\n14<\/td>\n5<\/td>\n<\/tr>\n
HomePlug 1.0 w\/ Turbo<\/th>\n85<\/td>\n10 – 20<\/td>\n<\/tr>\n
HomePlug AV<\/th>\n200<\/td>\n40<\/td>\n<\/tr>\n
DS2 \/ UPA<\/th>\n200<\/td>\n–<\/td>\n<\/tr>\n
HomePlug AV 500<\/th>\n500<\/td>\n70 – 80<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Table 2: Powerline Technologies vs. Maximum Throughput<\/h6>\n

You can see actual throughput plots in item 1 of Slow HomePlug? Five Ways To Boost Powerline Network Speed<\/a>.<\/p>\n

<\/a>3. I tried powerline before and it was lousy. Why try again?<\/h3>\n

A glance at Table 2 shows that the actual throughput delivered by powerline products has increased significantly from first generation HomePlug 1.0. Current products use at least third-generation chipsets which have significantly improved performance and stability. If you haven’t tried powerline since HomePlug 1.0, you should give HomePlug AV products a try.<\/p>\n

<\/a>4. Is it ok to mix different powerline technologies?<\/h3>\n

In general, no. If devices connect, performance will not be the best it can be because older, slower devices will cause newer faster ones to slow down. HomePlug thought this effect was so significant that they designed HomePlug AV (200 Mbps) so that it can coexist<\/em> with HomePlug and HomePlug Turbo, but not interoperate.<\/p>\n

“Coexist” means that both flavors will work, but only with like adapters<\/em>. (Actually original HomePlug and HomePlug Turbo will also interoperate, but with reduced performance). But “coexist” doesn’t mean that the different generations of HomePlug gear will play nice.<\/p>\n

Figure 1 shows around 60% reduction<\/strong> in HomePlug AV throughput when HomePlug Turbo devices become active at the same time.<\/p>\n

\"HomePlug<\/a><\/p>\n

Figure 1: HomePlug Turbo \/ AV Coexistence – HPAV first<\/h6>\n

No interoperation means you won’t get a connection between gear connected with HomePlug AV adapters and those connected with older types.<\/p>\n

<\/a>5. Is it ok to mix powerline with other networking technologies?<\/h3>\n

Absolutely. In fact, the largest manufacturer of powerline networking devices, Qualcomm Atheros<\/strong>, is placing a big bet on developing technology for what it has dubbed “Hy-Fi” (mixed wired \/ wireless) networking. When you can’t run Ethernet cable, powerline networking can be a very good alternative and much more reliable<\/a> than wireless repeating \/ bridging.<\/p>\n

<\/a>6. Will powerline work across multiple phases and circuits?<\/h3>\n

Yes. First-generation powerline gear worked only on conducted<\/em> signals. So it would not work across the two phases present in most U.S. homes that have 220V \/ 240V split-phase service. But current-generation adapters work on both conducted and radiated<\/em> signals, and work across phases just fine. for more information.<\/p>\n

The diagram below is taken from this Intellon Whitepaper<\/a> shows the multiple sources of cross-phase coupling in a typical household.<\/p>\n

\"Powerline<\/p>\n

<\/a>7. Will powerline support HD streaming?<\/h3>\n

It depends on your definition of “HD”. If you want to play straight 1080p Blu-ray rips with full “trick-mode” support (fast forward and reverse), you’re not going to get trouble-free performance from 200 Mbps powerline. But if you are ok with 720p HD or use a 1080p format that has lower bandwidth requirements, you might<\/em> be ok.<\/p>\n

The last time we tested this in HD Streaming Smackdown: The Rematch<\/a>, we found 200 Mbps powerline right on the edge for 720p H.264 video streaming. We haven’t yet tested 500 Mbps HomePlug AV because initial tests found too much throughput loss across our multiple test locations and 500 Mbps powerline adapters were just appearing. This is due for another look.<\/p>\n

That said, if you’ve been struggling with trying to do HD streaming via 802.11n wireless, I’d give powerline a shot. The bandwidth it supports is close enough that it may work in your situation.<\/p>\n

<\/a>8. Are powerline adapters safe?<\/h3>\n

Yes. Any product that plugs into a powerline must be certified against electrical safety standards in the country it is sold in.<\/p>\n

<\/a>9. My powerline network isn’t fast enough. How can I fix it?<\/h3>\n

First, make sure you are measuring throughput correctly so that you aren’t trying to achieve speeds that the technology can’t deliver. Don’t pay any attention to the link rates reported by the utilities supplied with some adapters. Just like wireless link rates, they bear little relationship to actual delivered throughput.<\/p>\n

To get an accurate measure of the speed of your powerline connection, you need to use a method that actually measures the speed that your connection is delivering. These include:<\/p>\n