Another innovation is the way Broadcom supports dynamic frequency selection (DFS) in nine additional 5GHz channels that sometimes are used by military and weather radars. The Federal Communications Commission allows Wi-Fi products to use these channels only if the radios can sense the presence of the radar signals and back off from those occupied channels. By supporting DFS, the access point is able to select from 24 instead of 15 channels for a transmission. In some of the DFS channels, radios can run at 1 watt, which is 250 to 500 milliwatts higher than allowed in the standard 5GHz channels. The higher wattage "can significantly boost range," says Rahul Patel, senior director for Broadcom's WLAN group.
Patel says the new chip is the only FCC-certified device that can run each of the nine DFS channels either in the standard 20MHz width or, by bonding two channels together, in 40MHz. Channel bonding is a key element in achieving the high 11n data rates.
Broadcom hopes to improve its WLAN position with regard to arch rival Atheros Communications by combining the new 11n chip and its attendant software stack with companion silicon and software for LAN access switches. The goal is a switch that can handle both wired and wireless clients automatically, without the need for a separate, specialized WLAN switch (often called a controller). Atheros 11n silicon is being used in several WLAN-access-point products being announced at Interop.
This "unified switch" silicon and software have been available for about 2 years from Broadcom, and several vendors are in production with it, says Michael Powell, senior product line manager for Broadcom's enterprise switching group. None of those customers have been announced, he says.
The new Broadcom chip is available in sample quantities, with production quantities expected in during the second calendar quarter of 2008. Pricing was not disclosed, but Broadcom's Powell says it will be "very competitive" with its rivals.