Access points that can carry data on multiple channels could be available within months. The "wideband" chipsets, from wireless startup Engim, could allow Wi-Fi access points to truly monitor the airwaves as well as handling data, and do away with the need for the dedicated wireless probes used in most Wi-Fi management products.
Reference access point designs are already in the hands of vendors, said the company, and there could be products "in six months". The system could also be used be used in specialised high-density environments, including multi-purpose wireless infrastructures on airliners.
Current wireless access points only talk on one channel at a time. The licence-exempt 2.4GHz waveband, used by 802.11b and 802.11g Wi-Fi systems, allows 11 channels, but it is only possible to have three that don't overlap (or four according to some vendors, if you don't mind some low-level interference). Engim's EN-3001 Wideband Wireless LAN chip set and access point reference designs for 802.11b and 802.11g are designed to use all three non-overlapping channels at once, allowing more clients within a single area to simultaneously connect to one Wi-Fi access point, according to Scott Lindsay, vice president of marketing at Engim.
"IT managers are frustrated," said Lindsay. "They thought they were buying the best thing for handling voice, and wireless monitoring, in one package." Current access points can do double duty after a fashion, he said, scanning for rogue access points and other problems when they aren't transmitting data. "But they scan the network for problems so infrequently, it would be a miracle if you spotted any problems."
This limitation has pushed users to using dedicated devices for scanning, which puts up the cost of Wi-Fi management applications. Lindsay believes that Engim-based access points could do both jobs at the same price as current access points.
To prove its concept, Engim has produced a thin access point, whose basic materials' cost is down below the magic $100 mark, so it could be built into cost-effective access points. Packet processing takes place in the chipset rather than on a separate processor, and Engim provides software building blocks for AP vendors. The radio chip has a new feature called called "transmit cancellation," which can prevent interference between an access point's transmitting and receiving antennas, by subtracting the transmit antenna's signals from the received signal.
Wireless networks designed to cover an office usually set up adjacent access points on different channels. That means the zone covered by an access point, typically about 300 feet, can only be served by one channel, leaving two channels unused, said analyst Craig Mathias, founder of Farpoint Group, in Ashland, Massachusetts. That's a waste of spectrum, he said, one that is not a big problem today but is likely to become one in the future, Mathias said. As more clients in a given space start to use Wi-Fi, access points increasingly will have to make use of those other two channels, he said.
An Engim-based network would use different spectrum where access points' footprints overlap, but multiple channels where there is no overlap, and would listen on all channels, so it would be aware of devices approaching its airspace, and make roaming more smooth - an essential for the fashionable idea of voice over WLAN. It would also allow location sensing without special probes.
Engim is also working on a radio for 802.11a, but is delaying that due to slower demand - and the fact that the slow take-up of 802.11a means its channels are not congested.
The system is already in use, at Matrx Aerospace Broadband Technologies of Illinois, whose prototype Galaxy wireless system for airliner cabins is built with an Engim-based access point. Galaxy will use multiple wireless bands as well as multiple channels within each band, to provide email and Web access, according to Jim Pristas, chief executive officer of Matrx.
Matrx hopes Galaxy's multi-channel fueled performance will persuade aircraft makers and airlines to switch to it from existing systems, when a deliverable version arrives, in late 2005
A second version of Galaxy, due in 2006, would offer a wider range of services through a system that could include proprietary wireless systems as well as Wi-Fi, Pristas said. Matrx plans to deliver multimedia services including video on demand to screens on seat backs, which would eliminate the weight and the maintenance costs of data cables going to every seat. "The average jet carries 2000lb of cable, so reducing it is core to their mission," said Lindsay,
The system might also be used for surveillance cameras, crew communication, handheld point-of-sale devices and other applications. The performance advantages of the purpose-built system could also serve another future application, in-flight wireless phone calls, he said.
In addition to suppressing interference from other Wi-Fi channels, the Engim chip set can take the information it gathers about anything going on in the spectrum band and pass it on to network managers. For example, it can detect interference from other technologies, such as Bluetooth and cordless phones, with location information so network managers can find and turn off or move those sources of interference, Lindsay said.
Prices for the EN-3001 chip set will vary based on volume and the customer's development needs, according to Engim. The chip set, as well as the AP-310 All Services Access Point at about $120 and the AP-320 Thin All Services Access Point at about $100, are available immediately to system vendors.
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