Stretching Wi-Fi

Reaching Out

D-Link's Super G with MIMO router has two internal and two external antennas.
D-Link's Super G with MIMO router has two internal and two external antennas.
Our testing focused on replacing an old 802.11b or g router in a home network without buying new adapter cards for every device (which would multiply the cost).

To this end, we tested the D-Link, Linksys, and Netgear routers with a regular 54-mbps card from Motorola, as well as with their respective matching cards. Ideally Wi-Fi tests would be conducted in a controlled, interference-free environment that enabled testers to produce repeatable results, but real-world conditions are rarely so pristine. Instead, we opted to conduct our tests in a private home, using several tools to measure the time that each of the setups took to transfer data to a notebook with the client card at varying distances away.

All three routers did a great job of extending our Motorola card's range, nearly doubling the coverage area of our plain 802.11g router while speeding up performance. With a regular router, we couldn't use the notebook any farther away than about 50 feet (and two rooms) from the base station. In contrast, each of the three test routers gave us whole-house coverage with very little drop-off in performance. We could even connect in the garden, which was 70 feet away. Though throughput there was clearly lower, the performance difference would matter only if you were transferring large files across your local network; and bandwidth still exceeded the 1mb-to-1.5mb maximum of most broadband Internet hookups. We lost a usable signal only when in the street, some 150 feet away.

The star in our tests with the Motorola card was the Linksys SRX, which delivered the best overall combination of range and speed. Its performance was similar to that of Belkin's less expensive Wireless Pre-N Router, which we originally tested back in January (see "New Wi-Fi Nearly Doubles Speed")--not surprising since both are based on the same Airgo True MIMO chip set, which sends multiple unique data streams over a single channel.

Unlike the other routers in our test, these Airgo-based routers can switch to whatever channel has the least interference, giving them great flexibility in environments that are subject to interference from neighboring networks, cordless phones, microwaves, or any other 2.4-GHz radios.

The D-Link Super G with MIMO relies on a new Atheros chip set that combines D-Link's Turbo beam-forming and compression with two internal and two external antennas in the router. Though the Super G was speedy, it could not match the range of the two Airgo-based routers.

The Netgear RangeMax uses Atheros's non-MIMO Super G chip and Video54's BeamFlex smart-antenna technology, which works with seven antennas on the circuit board (there's no external antenna) and optimizes on the fly in response to changes in the environment by using different combinations of antennas.

The Netgear's range was on a par with that of the Linksys, but its speed fell short of the latter--likely because the Netgear must use channel 6 in a mixed-mode environment.

MIMO vs. MIMO

A caution about jargon: Pre-N (on some product labels) refers to the coming superfast IEEE 802.11n standard (products meeting this spec aren't expected until late 2006). Pre-N products use MIMO (multiple-in, multiple-out) antenna technology, supposedly.

But don't make a buying decision based on these labels. MIMO isn't an industry standard or a trademark, and companies use it to mean different things. Also, the technology in various Pre-N products is proprietary: You won't be able to upgrade them to the final Wi-Fi-certified 802.11n standard, and they won't be interoperable with certified N products in high-performance mode.

Still, these issues shouldn't keep you from buying MIMO products. "What [consumers] should be concerned about is performance and backward compatibility," observes Kurt Scherf, vice president and principal analyst with Parks Associates.

Any of these routers will improve coverage, but the Linksys (or the cheaper Belkin) would get our nod for its winning range-speed combination. Don't bother buying the matching adapters unless you routinely transfer large files within your network (the extra bandwidth won't impact Internet speeds).

And don't worry too much about issues of future compatibility with 802.11n products: Two years is too long to wait to cover those dead spots.

For comprehensive coverage of the Android ecosystem, visit Greenbot.com.

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