Atheros 802.11n chips give PC OEMs performance options, power savings

Atheros Communications' dual-band AR9280 and single-band AR9281 PCI Express (PCIe) chips have been designed to address the high-performance and consumer markets of IEEE 802.11n for PC OEMs.

The new members of Atheros' XSPAN family both integrate the radio, baseband/MAC and host PCIe interface into a single-chip and are intended to be integrated on PCI Express cards.

The AR9280 supports a 2x2 MIMO configuration and delivers performance far superior to 802.11b/g chips. AR9281 supports a 1x2 MIMO configuration but still delivers performance superior to legacy 802.11 solutions. Both chips are designed to reduce power consumption and fit into ultra-small packages.

The chips are company's most silicon-area-efficient WLAN radio design to date. They deliver the industry's smallest 802.11n footprint in a 10mm x 10mm QFN package.

Reference designs are available for both PCIe half-Mini Card and full-Mini Card form factors and achieve new levels of system integration with up to 50 percent fewer components than competitive solutions.

The half-Mini Card is the smallest PCIe form factor, providing PC manufacturers with enhanced design flexibility to develop ultra-compact laptops or embed additional Mini Cards with complimentary technologies.

Up until now, most PC OEMs have offered 802.11n primarily in high-end laptop models. The new AR9280 and AR9281 allow manufacturers to enhance their core product portfolios with two design options:

• The AR9280 dual-band (2.4GHz and 5GHz) 2x2 MIMO PCIe design targets enterprise and high-end consumer notebooks. The solution provides leading 802.11a/g/n performance supporting up to 300 Mbps physical data rates, which enables up to 10 times the throughput and more than twice the range of 802.11a/g solutions. With this dual-band design, users will enjoy universal connectivity to any 802.11 network.
• The AR9281 single-band (2.4GHz) 1x2 MIMO PCIe design targets the lowest cost, lowest-power 802.11g/n solution for mainstream consumer PCs. The 1x2 configuration delivers 300 Mbps PHY rates on the receive side, while providing up to 150 Mbps in transmit. The 1x2 design is, today, the lowest cost MIMO configuration able to obtain Wi-Fi Draft 11n certification for PCs.

The AR9280 and AR9281 provide the highest level of 802.11n WLAN throughput, which allows PCs to remain in sleep-mode longer to extend battery life. Additionally, they feature Atheros' system-level power-savings protocols, algorithms and circuit design techniques which include:

• Dynamic MIMO Power Save (DMPS) conserves total system power by seamlessly downshifting to 1x1 MIMO operation when small amounts of data need to be transmitted or received. When the notebook is transmitting or receiving light traffic, the WLAN solution intelligently recognizes the reduced communications requirement and conserves power by switching to 1x1 mode. If the notebook begins heavy content transmissions, the WLAN automatically switches to the original 2x2 or 1x2 mode to ensure enhanced 802.11n performance. DMPS also senses if the notebook is plugged into AC or battery-power, and dynamically adjusts its MIMO mode to achieve an optimal performance/power balance.
• Unscheduled Automatic Power Save Delivery (UAPSD) increases a notebook's sleep time while transmitting real-time, moderate bandwidth traffic such as voice, audio and standard definition video. Typically, WLAN systems must spend significant time "listening" for transmissions to come from the access point (AP). With UAPSD, the AP sends the downlink traffic immediately after the client device requests the transmission, allowing the client to return to sleep much faster. Atheros' simulated-UAPSD technology brings power-saving benefits to PCs even when connected to legacy access points which do not have UAPSD intelligence.
• Atheros Wake-on-Wireless allows the host system to go into very low-power standby mode, but be awakened at any time by the network, or a remote device. The AR9280 and AR9281 chips support this operation by processing incoming packets independently, and waking the host only when a message requesting the host system take action arrives. This feature allows the notebook to remain in a low power state until the network or a remote device requests information.

"Atheros' latest 802.11n chips not only provide excellent throughput and range, but are also optimized for low power consumption, which remains a critical element in any mobile computer or communicator," said Craig Mathias, a principal with the wireless and mobile advisory firm Farpoint Group (Ashland, Mass.). "And packing all of this functionality into a single-chip product continues to demonstrate Atheros' mastery of semiconductor design and manufacturing technologies."

The configurations feature options to optimize the balance of performance, power and price:

• AR9280: 11n dual-band 2x2 MIMO for PCIe
• AR9281: 11n single-band 1x2 MIMO for PCIe
• PCIe reference designs for full Mini Card and half-Mini Card

The Atheros AR9280 and AR9281 solutions are currently sampling to customers and will be in volume production in the first quarter of 2008.

More information is available at www.atheros.com.