When wireless networks collide

A few weeks back I raised the question whether interference with 2.4GHz cordless phones made 802.11b network technology unfit for the home office. Since then, I’ve done some testing, and talked to readers and colleagues about their experiences. The verdict? While interference problems are common, they’re more of a nuisance than a problem, and pretty easy to remedy.

Last week, I set up the Siemens Gigaset 8825 and the Panasonic Gigarange Extreme (KX-TG2583S) on my office line. At first, I placed the wired Gigaset base station on my desk to the left of my 802.11b notebook, and one of the system’s cordless handsets to the right. Downstairs, I placed the Panasonic Gigarange base station and handset next to the 2Wire HomePortal 100 wireless gateway.

The Siemens AG phone was troublesome. I suffered a few dropped calls (one minute you’re talking, the next, dialtone), as well as a fluctuation in the signal strength of my 802.11b PC Card. The icon would flash green to yellow to red then green again, but the changes didn’t seem to affect the data connection. Moving the Siemens base station a few feet off my desk fixed the problem. When I switched the locations of the phones (Panasonic upstairs, Siemens downstairs), no new problems arose.

More than a dozen readers wrote me with similar problems, usually with Panasonic or Siemens models. Others offered suggestions. If repositioning the devices doesn’t work, try decreasing the power consumption of the access point or choose a 2.4GHz phone that lets you hard set the frequency channel instead of one that chooses the “best” channel automatically.

Similarly, many readers suggested buying an older 900MHz phone instead of a 2.4GHz one. The Wireless Ethernet Compatibility Alliance (WECA), WiFi’s marketing arm, says the group has tested four 2.4GHz phones and found two to be “a bit of an issue.” It too, recommends 900MHz phones. “You’ll get better range, better battery life, at half the cost,” says a WECA spokesperson.

Similarly, a few readers suggested giving up 802.11b gear in favour of the newer 802.11a products, which transmit 54Mbps of data on the 5GHz band. But abandoning your investment in favour of considerably higher priced products just doesn’t make sense.

When the answers to a technology problem include buying old technology or throwing out relatively new technology, something’s not quite right. Instead, why not ask, when can we run our data and voice over the same 802.11b wireless network? Where are the 802.11b voice-over-IP phones?

Waiting on the IEEE’s completion of the 802.11e specification. 802.11e adds quality of service to voice and multimedia applications. When 802.11e is added to the various 802.11x versions, voice and video packets will get priority over data packets, giving you voice quality that’s free from latency and jitter, says Sarosh Vesuna, senior director of strategic alliances and business development at Symbol Technologies and technical chair of the WECA.

“Once you have a WiFi network, you’ll gradually migrate to a wireless voice-over-IP phone because you already have DSL or a cable modem and a WiFi access point. Why not just buy a WiFi phone?” Vesuna says.

The IEEE expects to finalize the 802.11e specification by year-end, but some say the date could slip to mid-2003.

If you don’t want to gradually migrate and have deep pockets, you can add 802.11b phones to your wireless LAN today – using gear from Symbol and SpectraLink. Both companies sell 802.11b phones and gateways that use proprietary QoS technology that’s becoming the basis of the 802.11e standard. But there’s no reason why you can’t set up such a system in a small office – except cost. For instance, Symbol’s NetVision phones cost US$699 each (list price); the four-port gateway costs US$1,995 and the eight-port gateway costs US$3,595. Gateways also come in 16- and 24-port models.

Even so, Rich Watson, Symbol’s director of telephony, says adding 802.11b phones to the small office wireless LAN is a smart move and can even save money in some cases. “It’s a good environment because those networks don’t typically have a lot of data running over them,” he says. “You can add multiple access points and do roaming, and since the phones are IP addressable, they become just another managed device on your network. And in the case of a new deployment, it saves you from having to run a phone line to each desk.”