Wi-Fi coverage spotty? Put your power lines to work

It's a different story at my mother's house in Chicago during the holidays, when a variety of computer-toting relatives show up. The Wi-Fi router in the front of the house doesn't deliver a good signal to the rear of the building, or to the basement. Those of you with large houses know the feeling.

One easy solution: Stay out of the basement. Or get a better Wi-Fi antenna, capable of picking up wireless signals at longer range, even through walls. You can pick one up at Home Depot or Best Buy for $40 or $50. There are also Wi-Fi range extenders, boxes that capture the signal from the main router and relay it to distant regions. They cost about $100.

But there's one more option to consider: Turning wall outlets into a computer network. The copper wires that distribute electricity through a house can also carry data, with help from a power line network adapter.

The notion of sending information over power lines has been around quite awhile. Amperion Inc. of Tewksbury and Ambient Corp. of Newton have spent years working on technologies for pumping high-speed data over the nation's electrical grid. But there are also a lot of devices aimed at the simpler challenge of networking houses and apartments.

The Wi-Fi boom has pushed power line networking products to the back of the retail shelf. According to a report last year from the consulting firm Parks Associates, 53 percent of Americans with home networks use Wi-Fi, 28 percent have strung Ether net wires around the house, and 8 percent use power line systems.

I wonder why. Gadgets like the D-Link Systems Inc. DHP-303 power line adapter are a simple, handy way to pump digital data all over the house.

The DHP-303 system, priced at $140 for two adapters, is easy to install. Just plug the first adapter's Ethernet cable into a DSL or cable modem, and then plug the adapter into a wall outlet. Don't plug into an extension cord or power strip if you can avoid it; these tend to reduce network speed. If you've already got a wireless router, plug the adapter's Ethernet cable into one of the router ports. This way, it's possible to use power line networking and Wi-Fi at the same time.

Now you can get network access in any room with a power outlet. Just shove another adapter into the wall, and connect its Ethernet cable to any compatible device - a computer, digital video recorder, or video game console. It's like running a standard Ethernet line - just plug it in. If there is more than one networkable device in the room, invest $20 or so in an Ethernet hub and share the signal. To hook up devices in other rooms, just buy more adapters.

D-Link says you can mix and match their adapters with those from competing companies like Cisco Systems Inc.'s Linksys devices. But some companies, like D-Link and Netgear Inc., use a network technology called DS2, while Cisco and other providers use a system called HomePlug. The best bet is to pick one standard or the other, and stick to it.

Power line networks are naturally more secure than Wi-Fi, because they can't beam personal data to any passerby with a laptop. But there's a slight chance a next-door neighbor with a power line adapter could pick up your network transmissions. So D-Link and other companies offer a feature that encrypts all data moving over the network. With Wi-Fi, you must set up a unique name for your router and an encryption password. The D-Link system simply requires you to press a button on each adapter. From then on, all network data are scrambled.

The D-Link adapters offer network speeds as high as 200 million bits per second, slower than the latest Ethernet gear, but much faster than Wi-Fi - on paper. But networks never deliver their promised top speeds in real life. I tried transferring a 165-megabyte file, first over the power line network and then by using Wi-Fi-G, which claims a theoretical top speed of 54 megabits per second. It wasn't even close - Wi-Fi made the transfer in a mere 80 seconds, while the D-Link power line network needed 140 seconds. That wasn't supposed to happen. But it could be due to a quirk of my home electrical wiring, and results might be different in your house.

In any case, the D-Link system is plenty good enough for Internet surfing, and even for gaming. While connected to a Sony PlayStation 3, it delivered good performance in a Killzone 2 multiplayer massacre. I still got slaughtered, but I can't blame D-Link. After all, the box says "plug and play" not "plug and win."

Hiawatha Bray can be reached at bray@globe.com.