• United States

Embedded interference-fighters on the horizon

Jul 09, 20032 mins
Cellular NetworksNetwork SecurityWi-Fi

* Mitigating interference should improve WLAN performance

“Interference is the enemy!”

So said David Barach, a participant in a panel called “Wi-Fi on Steroids” at the recent 802.11 Planet show in Boston. Barach is also executive vice president of business development at Extricom, a company currently in stealth mode.

As mentioned in the last newsletter, all the companies on the “Steroids” panel are building technology for other vendors’ access points (or wireless LAN switches) that they expect will improve the throughput and range of 802.11 radios by alleviating the impact of interference. Last time, I briefly described the efforts of Airgo Networks and Engim; this time, I’ll describe Extricom and Smart Packets.

Extricom’s technology enables all access points (AP) in a network to be aware of every client at all times, Barach said. So clients associate with an AP only once, rather than requiring APs to hand-off associations and change channels as clients roam.

“802.11b and 80211g, for example, go on different channels,” Barach said.  “You don’t have to gear-shift to a separate channel for voice, either.”

For its part, Smart Packets takes a packet-fragmentation approach to increasing a traffic stream’s resistance to interference. According to Murat Bahadiroglu, founder and CTO, the company’s software creates a “neural network” that enables an AP to determine, dynamically, what the optimum length of IP packets should be to reduce bit-error rates caused by interference.

“The smaller the packet, the less susceptible it is,” he explained.

But the neural network balances the packet-size consideration with the overhead incurred by the additional headers that are created when a fewer number of larger packets are chopped into a larger number of smaller packets.

Striking the right balance of packet length and overhead “is our secret sauce,” said Bahadiroglu, who added that tests of his company’s technology have demonstrated 2:1 to 3:1 performance improvements in APs.

The efforts of the “Steroids” vendors – Airgo, Engim, Extricom and Smart Packets – were validated during a separate panel session in which Aberdeen Group analyst Russ Craig said that 802.11 APs could use some independent third-party benchmarking.

“Performance of today’s APs is all over the map,” he asserted.

Note that Wi-Fi Alliance certification reflects only that products tested will interoperate with other products in the alliance’s testbed. Certification doesn’t necessarily assure full compliance with the complete set of 802.11x specifications or any minimum performance threshold.