It seems like every major wireless protocol is coming out with a variant that can make it under the low-power limbo bar. Bluetooth has spawned Bluetooth Low Energy and ZigBee now has a low-power healthcare profile. Not to be outdone, the Wi-Fi Alliance developed 802.11n to be a high-speed, lower power alternative to 802.11a/b/g, and it’s been rapidly adopted. Recently even lower-power versions of 802.11n chips have been coming on the market. But the Big Kahuna is 802.11ac, for which first silicon is just starting to appear.
Operating in the 5 GHz band, 802.11ac chips will
- have 2-4x the bandwidth of 802.11n (80 and 160 MHz channels vs. 40 MHz for 11n);
- achieve a data throughput of up to 1 GBbit/s—~10x better than 11g and about 3x better than 11n for 2- and 3-stream implementations;
- support multi-user MIMO with up to 8 data streams (vs. 4 in 11n);
- support up to 256-QAM vs. 64-QAM in 11n;
- theoretically result in a considerably better power profile than 11n.
The “theoretically” hinges on the fact that the 802.11ac specification is yet to be ratified. The Initial Technical Specification Draft 0.1 was confirmed by IEEE 802.11 TGac on January 20, 2011. The specification isn’t expected to be finalized until mid-year at the earliest, at which point the Wi-Fi Alliance expects to ratify it, though IEEE ratification will take longer.
Are We There Yet?
That hasn’t stopped a rush to market with ‘pre-ac’ silicon, exactly the same thing that happened before the 802.11n specification was ratified. Last time the first out of the chute was Broadcom, whose ‘pre-n’ 802.11 chips hit the market well before the warring camps in the IEEE working group had ironed out their differences.
At CES earlier this month Broadcom announced that it is sampling 802.11ac silicon—the BCM43xx family, which it refers to as ’5G WiFi’—though it is yet to announce a date for full production. Early adopters of Broadcom’s 11n chips took a big chance but came out unscathed. Will they be as lucky this time? According to Michael Hurlston, Broadcom’s senior vice president of Broadcom’s Home and Wireless Networking business unit, ”I’m confident that any changes to the spec beyond this point and before final ratification will be window dressing, and relatively small.” History, hype, or hope? Only time will tell. Still, having pulled it off before—and pushing a lot of chips, as it were, onto the table—it would be foolish to bet against Broadcom.
Also joining the ‘pre-ac’ race is Redpine Networks, currently sampling its Quali-Fi™ 802.11ac chip. The Quali-Fi product is accompanied by Redpine’s software framework that includes an access point, Wi-Fi certified client and Redpine’s Wi-Fi Direct™ functionality. Redpine CEO Venkat Matella tells Low-Power Design that modules with 801.11ac chipsets will be available late this year or early 2013.
I’d be very surprised if Qualcomm/Atheros and Samsung—who co-chair the IEEE 11ac Task Group—as well as committee members Cisco, Intel, LG, Marvell, Mediatek, and others—didn’t announce 11ac chips shortly after the specification is ratified—if not before.
With even once power-hungry Wi-Fi now joining the low-power race, low-power wireless is no longer just a trend, it’s mainstream. We may not be ‘there yet’—and never will be, since the goal is one you can only approach asymptotically—but silicon vendors are making an impressive amount of incremental progress. Stay tuned for more exciting developments.
