New 11n chips could soon make 802.11abg gear extinct

Setting the stage for a new generation of 802.11n wireless networks, Wi-Fi chipmaker Atheros last week launched a family of enhanced chips that include some of the optional features of the recently ratified final 11n standard. Many enterprise-class wireless LAN makers base their systems on Atheros chips, and with the enhanced standards-based components available, it likely won't be long until 802.11abg products start disappearing from vendor inventories altogether.

The company's latest AR9300 family supports 3x3 MIMO technology with three spatial streams that yield 450Mbps data-connect rates, up from the typical 300Mbps connect rates in configurations with two streams. Most Wi-Fi products on the market today run two spatial streams regardless of the number of transmit and receive antennas in their access points (AP), because that is the maximum their chipsets support.

The 9300 products support the Transmit Beamforming (TxBF) and Low Density Parity Check (LPDC) options to the 802.11n. TxBF locks time and phase of a wireless signal together to boost signal reception. Both transmitter and receiver (client and AP) must participate in the calibration process, explains Pen Li, Atheros product manager.

LDPC is a method of forward error control coding, he says, that improves overall signal quality.

In addition, the chips support a capability called Maximum Likelihood Demodulation (MLD), which provides a 15% to 30% increase in range, he says. Maximal Ratio Combining (MRC) allows receivers to optimally combine different signal paths in a way that improves range by another 20%, Li adds.

Atheros and others are also trying to bring mobile devices better into the 802.11n fold with chipsets that support just a single stream. Power-challenged devices such as mobile phones can't afford to support more than a single stream. Yet they need to be recognized by an 802.11n AP seeking multiple antennas for MIMO.

Atheros says its AR6003 single-stream 11n chip for mobile phones and consumer devices has beaten the power consumption industry record it had already set with its AR6002 11g and 11a chips by further slashing power consumption by 20% while "doing the 11n higher rate," says Tim Peters, manager of mobile communications product marketing.

Atheros didn't mention expected throughput speeds. However, competitive Wi-Fi chipmaker Broadcom announced its BCM4329 single-stream mobile 802.11n chipsets late last year, claiming up to 50Mbps throughput

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.