What is power-line networking?
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| HomePlug Certification Mark |
 
What is power-line networking? | |
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How does HomePlug Powerline work?
The HomePlug Powerline Alliance hammered out the HomePlug 1.0 specification last year, with broad industry support from chipset makers Intellon and Cogency and networking manufacturers NetGear, Linksys, Phonex, and GigaFast. HomePlug 1.0-certified products already appear in volume on shelves and can facilitate network communications among PCs, Macs, routers, and Internet devices such as Net radios, all through 110V power lines.
Power-line adapters do what all analog communication devices do: translate data into a carrier-signal format so that it can be transmitted to another device. The big difference is that 110V power is a tough carrier signal; it's not a perfectly regular sine wave. The signal gets jagged with line noise, spikes, surges, and brownouts (periods of low voltage), all of which makes it a rough medium for communications. But thanks to some smart programming, HomePlug adapters can weather most of these problems and keep your connection live.
What's the setup?
Power-line adapters come in two basic flavors: those with USB interfaces, and those that plug into Ethernet ports. Want to share a printer between computers in two rooms? Plug a power-line adapter into each computer. Want to share broadband Internet access? The simplest way is with an Ethernet broadband router. With the router sitting between your cable or DSL modem and your hard-wired online computer, you're free to expand your broadband access to other computers. Simply attach a HomePlug power-line adapter to the router and plug it into the wall power socket. Then attach an Ethernet or USB power-line adapter to any PC, Mac, or Internet radio you want to access. You may need to install a driver onto your PC and maybe run your computer's Internet configuration software, but otherwise, it's a fairly easy operation.
Typical Powerline network setup
How does it compare with other networking standards?
HomePlug's standard has physical advantages over its competition, too. It doesn't require special wiring like Ethernet networks do, and it can do something that wireless networks can't: communicate between the attic and the basement of a four-story house. Wireless networks have a working range of about 150 feet, and the connections get slower the farther the wireless receiver is from its base station. HomePlug networks, on the other hand, have a range of about 1,000 feet of power cable.
Power line's theoretical data transfer limit is 14 megabits per second (Mbps), but in practice, it exchanges data at less than half that rate. That's still faster than the more affordable of the two Wi-Fi specs, 802.11b, which has a practical throughput of 4Mbps to 5Mbps. But of course, it's slower than 802.11a's practical 22Mbps and fast Ethernet's 100Mbps. In other words, power-line networks are plenty fast enough for sharing files, Internet access, and peripherals such as printers, though maybe not great for a streaming videoconference or multiplayer gaming.
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*For 100Mbps network
The cost of power-line networking
HomePlug power-line networking is often accused of being expensive, but it's not necessarily any pricier than the alternatives. You can pick up HomePlug adapters from GigaFast and NetGear, for example, for between $80 and $100 apiece--in about the same range as Wi-Fi adapters (which retail for about $60 to $100). With these adapters, a three-computer power-line network would cost around $300. A Wi-Fi network will cost roughly the same when you factor in $150 for the base station. And the Wi-Fi gear tops out at 11Mbps. At longer range, it's even slower; in fact, you may need to pay an extra $60 or so for a range extender to get comparable data rates.
But in general, HomePlug isn't the cheapest way to network a house or office. Home Phoneline (HPNA 2.0) USB adapters cost around $30 (or $100 for HPNA Ethernet bridges), which can work out cheaper, if you have phone lines in every room you want to network. And to enable Internet sharing over HomePlug networks, you need to spring for a broadband router, which will put you $60 or so above a wireless network budget. But that's small beans when you factor in the system's setup simplicity.
How do I set up a power-line network?
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