Wi-Fi Alliance plans to certify 802.11g WLANs this summer

Computerworld - The Wi-Fi Alliance plans to start interoperability and certification testing this summer of new wireless LAN products based on the still-evolving 802.11g standard, which offers 54M bit/sec. data in the 2.4-GHz band. That compares to 11M bit/sec. throughput for WLAN products that operate in the same unlicensed frequency band and use the better-known 802.11b.
Atheros Communications Inc. and Intersil Corp. have both developed 802.11g chip sets, while manufacturers such as Cisco Systems Inc. and Proxim Corp. plan to sell WLAN access points and cards incorporating the high-speed 802.11G standard. Several hardware vendors are already selling 802.11g products, including Apple Computer Inc., Santa Clara, Calif.-based NetGear Inc. and D-Link Systems Inc. Those products are out, even though ratification of the 802.11g standard by the Institute of Electrical and Electronics Engineers Inc. has not yet occurred.
That decision is expected between June and August, according to Dennis Eaton, chairman of the Mountain View, Calif.-based Wi-Fi Alliance.
But analysts and Symbol Technologies Inc., a key supplier of WLAN equipment to a number of vertical markets including transportation and retail, wonder whether 802.11g is ready for prime time this year.
In order to receive certifications from the Wi-Fi Alliance, 802.11g products must be backward-compatible with the 802.11b standard and support simultaneous operation of both 802.11b and 802.11g clients, Eaton said. That presents manufacturers with a tough technical challenge, Eaton said, since the "b" and "g" standards use entirely different modulation schemes -- Complementary Code Keying for "b" and Orthogonal Frequency Division Multiplexing for "g."
Since a "g" access point cannot hear a "b" client due to the different modulations, the "g" protocol includes technology that allows the access point to determine whether there is a channel clear of traffic in the 2.4-GHz band on which it can transmit, Eaton said.
Interviewed at the Gartner Inc. enterprise wireless conference in Los Angeles yesterday, Ray Martino, vice president of the network systems group at Holtsville, N.Y.-based Symbol, said the forced sharing by "b" and "g" clients of the same frequency band means enterprise customers with a large installed base of 802.11b WLANs will pass on installing 802.11g access points.
Martino also cited potential conflicts between older "b" clients and the new "g" gear in environments where enterprises also use Bluetooth short-range communications devices, which operate in the 2.4-GHz band. In such installations -- for example, United Parcel Service Inc. sorting hubs where UPS uses Bluetooth scanners and 802.11b WLANs -- the conflicts in the 2.4-GHz band could be difficult to manage and work around.
Enterprises that