Startup chipmaker Quantenna Communications says that it can push 1Gbps over regular WiFi without defying the laws of physics. This isn't as hyped up as it sounds at first glance. The company's initial goal is to cover houses with a combination of high bandwidth and mesh networking, making it possible to push multiple streams of video and data without glitches at slower rates—as fast as 100 to 200Mbps. Their future sights are set on the enterprise market where 1Gbps might mean something.

Quantenna can claim to have made the most interesting announcement about WiFi since Draft N devices started to ship in earnest. By providing twice or three times the current throughput, Quantenna might allow WiFi to step into businesses—as well as the homes they're initially targeting.

The company's founder, chairman, and chief executive Behrooz Rezvani said in an interview that WiFi used as a point source in a home isn't very effective. He said, "One source point cannot cut it—you cannot solve the whole networking problem by having one source, one radio." This was one of the reasons Draft N was developed in the first place: greater coverage through several different improvements. (That's the preratification marketing name for the engineering group IEEE's 802.11n protocol; the standard won't be formally approved until next year.)



Quantenna fits four to eight radios, a processor,

a DSP, and other components into a tiny package

But Draft N still can't cut it by itself, even though it marked a large improvement over 802.11g. "You cannot light the house with a single lightbulb," he said. As with lighting, even a bright bulb leaves some areas in shadow, while others are well lit. Draft N might reach two to four times further than 54Mbps 802.11g, but that still leaves some parts of a home in the dark.

Solving problems

Rezvani said that Quantenna wants to solve three separate problems for home Wi-Fi networks: overcoming interference from dense arrays of networks in apartment buildings, penetrating the thick walls often found in European homes, and spreading a signal out to cover expansive American houses from basement to upper floors.

Its solution was to use optional elements in the 802.11n standard that let them add more antennas and radios than any system sold today for the home or enterprise. Rezvani said several times in the interview that his far-larger competitors like Broadcom or Atheros could choose to enhance their products in the same way, but hadn't yet done so; I've heard nothing publicly or privately about a roadmap including these features, either, even though they have long been under discussion.

Most Draft N access points currently have either two or three send-and-receive antennas. This provides enough diversity to steer signals through beamforming—a kind of "body English" for radio waves—and to hear and differentiate fainter signals or those overlapping with other networks.

Draft N also requires two separate signal streams for spatial multiplexing. With spatial multiplexing, the multipath reflection of signals across space are used to WiFi's advantage to as much as double throughput.

Devices on the market currently use two spatial streams, each of which can use (depending on country-specific regulation) up to 40MHz "wide" channels, which are twice as wide as the normal channels used in 802.11a, 802.11b, and 802.11g. With other improvements over 802.11g, Draft N in its mandatory basic form can push 300Mbps of raw data between a gateway and a client.

Quantenna's improvements

Where Quantenna improves on this is by using four antennas each for sending and receiving and four radios for each band. With a "4x4" array, "You can shape the beam a lot better," Rezvani said. Rezvani says that their 4x4 quadruples the area covered by a current device using the same power. You can "double throughput for the same radius, or double your radius for the same throughput," he said. More antennas increase effective antenna gain.

Quantenna has initially announced three chipsets, all of them far smaller and requiring fewer external components than the equivalent products assembled from components made by other WiFi chipmakers. The QHS450 (2.4GHz) and QHS600 (5GHz) both have four radios and work in a single band; the QHS1000 has eight radios and works concurrently in both 2.4 and 5GHz bands. They'll ship in 2009.

For the home, Rezvani expects that manufacturers will use the firm's chips in 4x4 mode where the four radios are split into two sets, each transmitting the same data. This redundancy lowers real throughput, maxing out at 100Mbps in 2.4GHz and 200Mbps in 5GHz, but increases reliability by sending each bit along two separate paths.

But the same chips can give up redundancy in favor of performance, useful in an enterprise where nodes may be closely spaced. In that scenario, each set of two radios would pair with a 2x2 antenna array, allowing the single-band chipsets to handle two wide channels at the same time, and the dual-band chipset to handle four separate channels across two bands concurrently. This allows the QHS1000 to deliver a raw aggregate over 1Gbps.

The company has developed a reference design for a small, concurrent dual-band mesh node that could be used to extend signals through a home. The device uses the QHS1000 so that it can use whichever band and channels are most appropriate to spread data in a mesh among nodes, and feed out the highest throughput to devices that need it, such as streaming high-definition or high-speed data transfers. The company's mesh technology is built on 802.11s, another IEEE standard that's still working its way to market. (Mesh nodes exchange data among routes that they agree on among themselves, rather than through a hub-and-spoke layout.)

Because the design can use multiple channels at once, the mesh nodes can coordinate on changing channels in band—keeping data flowing over one band while they switch to another—or dynamically reconfigure the number of active channels by switching among 2x2 and 4x4 configurations while continuing to send data. This overcomes limitations in single-radio mesh nodes that have to reuse the same spectrum by sending the same data twice or more times to reach more distant nodes.

Rezvani pointed out that the company is more interested in getting chips into equipment makers' hands than in proscribing what their products do. He expects a lot of different kinds of products to appear, because of how Quantenna's chips can be configured for different uses from one second to the next.

Quantenna is estimating a cost of about $20 for its single-band and $40 for their concurrent dual-band chipsets in large quantities in 2009. Those prices are far higher than current Draft N chipsets, but Quantenna has integrated components that aren't usually included in the basic chipset costs.

Startup chipmakers in an established market like the WiFi realm have to come with products that are instantly mature, unique, and easy to work with. Quantenna may be far ahead of its less nimble brethren, or it may be days away from announcing similar products themselves.

In either case, WiFi is about to take a big leap forward in range, speed, and flexibility without a commensurate jump in price.