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Apple offered a quiet update note to its two main base station models today with a big boost in speed and coverage: The company put in a note on the data page (see "Even faster performance") and mentioned in passing to media who were briefed that its AirPort Extreme and Time Capsule base stations would see a boost of up to 50 percent in data throughput and an increase in range of up to 25 percent over the immediately preceding models.
How? 3x3. Engadget found the FCC documents that supports that statement before the announcement today, although the writer didn't explain what this means.
In the MIMO (multiple in, multiple out) antenna system that's used in 802.11n, designers have lots of choices in how to build in range and resiliency, and those choices have increased as silicon and antennas have become cheaper.
Most consumer 802.11n access points use a 2x2 MIMO array, which is two receiving and two transmitting antennas. Each antenna pair is typically handled by a separate radio chain. Each radio chain can transmit unique data for higher data rates, or the same data as other radio chains to increase redundancy, and thus provide better reception at lower rates.
These radio chains use spatial multiplexing, which allows a kind of "body english" in which varying power fed through antennas steers a beam so that it travels a unique path through space, using reflection of objects as one of the characteristics that forms the beam. Multiple receiving antennas decode these individual chains and reassemble data into what was sent in the first place.
In 802.11n, each spatial stream in the highest-rate mode can act like a separate full-speed connection. Since roughly 75 Mbps is the raw rate for 20 MHz channels and 150 Mbps for "wide" 40 MHz channels, a two-stream device maxes out at 300 Mbps of raw throughput.
Nearly all 802.11n base stations sold to date use 2x2 arrays coupled with two spatial streams; some also offer 2x3 arrays for redundancy with just two streams. However, chipmakers have been planning for some time on getting 3x3 arrays with three spatial streams into the market with a raw 450 Mbps rate. Apple may be the first consumer access point maker to bite, although there are definitely other 450 Mbps APs on the market. (See next paragraph for update.)
[Update! An informed commenter--see below--notes that there's only a single AP that does three streams. So Apple isn't slipping in higher bandwidth here, just better signal diversity and performance.]
The additional transmit and receive antennas improve how far signals can travel to a client, and how sensitively an access point can pick up distant transmissions. This accounts for Apple's statement on improved range. It also provides improved bandwidth further from the base station; the data rate doesn't drop off nearly as fast as with 2x2. The "up to 50 percent" figure relates to a range of distances, not close up to the base station.
The Wi-Fi Alliance just approved a testing regime for devices with three spatial streams, and all the major Wi-Fi chipmakers were involved in that testing. Our informed commenter says it'll be until late 2010 before we see a large number of 3-stream devices; other opinions?
The WiMax developer and licensed spectrum holder NextWave will acquire metro-scale Wi-Fi gear maker Go Networks: Go's equipment uses MIMO to fill more space at lower cost, the company has said. NextWave, a successor firm to the 1990s cell operator and Supreme Court case victor over spectrum auctions, has a portfolio of WiMax hardware and a set of licenses they purchased in the recent advanced wireless services auction. NextWave also acquired some German WiMax licenses last month.
NextWave is obviously assembling a set of technologies that they can roll out in test markets that they have spectrum in, and will be well positioned to test the effectiveness of MIMO-based Wi-Fi as a complement and supplement to WiMax in urban areas.
The Go Networks' deal is valued at $13.3m with a separate assumption of $7.5m in debt. Go would also receive $25.7m in stock for meeting milestones 18 months after the deal closes.
I'm trying to make sense of Ruckus's rural strategy for its IPTV products: The company uses multiple-antenna technology combined with proprietary streaming algorithms to provide voice, video, and data (802.11b/g compatible) across a home. The rural angle is intriguing, because rural telephone companies want to bring newer services (and higher per-customer revenue for the same wired infrastructure), but they can't afford to rewire homes to handle the network for multimedia and VoIP traversing a house.
Enter Ruckus. They say that because their system can carry streaming video and deliver other services, they're the perfect complement for rural telcos. The telco still does a truck roll, but Ruckus claims its MediaFlex system of gateways and adapters takes under an hour to install, and future additions can avoid a truck roll.
An hour is a pretty nice bar to set to keep costs low, and compares favorably to other home installs. A DirecTV installation at my house required two installers and about an hour to mount a satellite antenna, set up the receiver, and train us on the system. Obviously, the satellite industry considers an hour a profitable installation when factoring in lifetime customer value.
By contrast, in a DSL textbook I read nearly a decade ago, new telco services weren't considered profitable by large phone companies until they reached the point when only five percent required truck rolls. It took DSL and cable years to reach the point where most installs involve just sending a modem out. This has changed completely again with triple-play services, as Ruckus notes.
The latest press release from Ruckus notes 16 more rural telcos in addition to several they'd already signed.
Did MIMO run over Eileen McCluskey's bike as a kid? I'm slightly baffled by the treatment of MIMO technology in this otherwise reasonable set of consumer advice about Wi-Fi in the Boston Globe yesterday. It's possible the single source cited in the article poisoned her information well.
"These Multi Input, Multi Output gadgets achieve excellent signal quality and range by hogging the wireless spectrum up to 219 yards away. If you live in the city or suburbs, your MIMO router will knock out your wireless-enabled neighbors' connections." Huh?
Here's my letter to the editor just sent off to the Globe:
"Less Is More" (Apr. 9, 2005) contains a glaring error regarding multiple antenna wireless networking. The reporter says that MIMO (multiple not "multi" input/output) gateways hog spectrum and knock out neighbors' reception. This is entirely untrue. MIMO gateways for Wi-Fi, unlike previous range-extending Wi-Fi, are more sensitive receivers not more powerful transmitters.
It used to be that to extend range, you pumped up the volume (increased signal power output), which could interfere with neighboring networks. MIMO uses several antennas to better reconcile radio signals as they reflect off walls and metal objects. This allows the technology to more discretely receive fainter or less clear signals from further away.
There is the danger that a newer form of Wi-Fi, called 802.11n, that will be on the market soon may interfere with older networks in some cases, but Wi-Fi product makers haven't finalized the standard, and it's one of their key concerns.
The other also states that MIMO won't work with free Wi-Fi hotspots. This is entirely untrue. Current MIMO gateways and future gatweays that use MIMO as one piece in a faster Wi-Fi standard are entirely compatible with Wi-Fi equipment sold as long as ago as the first devices in 1999. MIMO devices won't communicate at their highest possible speeds except with compatible devices from the same maker (today) or with the newer standard with any maker (in about 3 to 6 months).
Tim Higgins has reviewed NetGear's RangeMax 240 and found it can top 100 Mbps of throughput, but wipes out nearby 802.11b/g networks: His tests show that the device, based on Airgo's third generation of MIMO chips, doesn't stop using two 802.11b/g channels' worth of spectrum when nearby networks are active. Read more over at our MIMO + N blog.
Airgo announced its next-generation MIMO chips today: Airgo's newest entry in the MIMO field will hit 240 Mbps of raw throughput when communicating among identical devices. The new chips are backwards compatible with 802.11a, b, and g, and previous Airgo-based devices.
Read the rest of the story at MIMO+N News.
Tim Higgins of Tom's Networking offers his exhaustive look at the NetGear RangeMax Wireless Router: This device uses Atheros's Super G technology combined with Video54's multiple antenna approach. The folks at Airgo say that Video54's MIMO isn't MIMO because it doesn't support spatial multiplexing (multiple signals taking different paths over the same frequencies). Video54 says multiple antennas are multiple antennas; they're using a phase-array approach per packet in which each packet can be sent through a different antenna combination. The device has a street price of just $118, far below its "true MIMO" competitors.
Higgins thinks that the device delivers on some but not all of its claims, and that because four different technologies are involved (three from Atheros then Video54 on top) he has some issues with the simplicity of it, too. He doesn't know which technologies need to be turned on, off, or changed in order to achieve the best results with that combination. That's a key advantage for the True MIMO line of products using Airgo chips: it's essentially one technology that wraps around all these ideas while delivering better results.
PC World's advice: go MIMO if you need range: A very sensible array of advice from Becky Waring over at PC World based on testing several of the current MIMO (multiple-in, multiple-out) Wi-Fi gateways and adapters on the market. Waring offers the same recommendation that I have, which is that for homes or small businesses for which the price premium overcomes the cost and/or hassle of installing many individual access points, a MIMO gateway makes a great deal of sense.
I would add that for networks in which throughput over Wi-Fi is a significant issue over short distances (up to about 50 feet), MIMO is the only technology on the market that can increase throughput even with existing 802.11g cards to their highest level at their greatest distance.
If you don't need range or speed and adding access points is not a big deal--you have Ethernet installed throughout a house or office or understand how to configure Wireless Distribution System and can deal with its limitations--then the price premium is probably worth sitting on your wallet as the cost of this technology drops rapidly because of unit sales and competition.
Meanwhile, Mobile Pipeline's editor writes about MIMO's early use in business: It's not ready for the enterprise yet, but even consumer-scale and early small-office MIMO gear has unmistakable benefits in certain cases that Haskin lists.
Tim Higgins exhaustively reviews Linksys's rendition of Airgo True MIMO technology: TIm runs the Linksys unit through its paces, and notes that it does deliver as promised on range and throughput. But in his conclusion he states points I agree with: for three times the cost of a regular extended range 802.11g access point, it's only worthwhile if you need additional range or throughput.
Tim wrote: "At least for now, no matter what moniker it goes by--True MIMO, SRX, Pre-N, VLocity, RangeMax--MIMO is just another non-standard performance-enhancement technology. It doesn't solve WLAN problems caused by an already over-crowded 2.4GHz band and has a snowball's chance of being compatible with 802.11n gear that won't appear until sometime next year. But at least Airgo's True MIMO flavor delivers the goods for unequalled throughput over range performance."\
Tim's more optimistic about real 802.11n gear appearing next year. It's possible we won't see future-proofed 802.11n--devices that can be upgraded to the final standard--until 2007.
Mobile Pipeline says buy MIMO now if it fits a particular need: David Haskin, editor in chief, writes about his experiences with Linksys's new MIMO-based router and PC card. He's very positive about its throughput, performance, and interoperability. But he raises the same three concerns I have about recommending MIMO: price for current performance, future support of its highest speeds, and interoperability among multiple MIMO vendors.
The Linksys unit at $200 for the gateway is particularly high priced, especially compared to Belkin's MIMO which has dropped to well under $150 street price. Haskin notes that people with a compelling reason for MIMO now--greater throughput or greater supported distances--should consider it.
MIMO is cropping up all over: NetGear is the latest to announce a MIMO (multiple-in, multiple-out) product. They're partnering with Video54. Linksys has apparently chosen Airgo. Samsung and Athena announced single-chip silicon yesterday.
The near-term problem with MIMO isn't with the technology itself, but rather the non-standard higher speed modes. No one is claiming interference, but these modes won't be certified by The Wi-Fi Alliance or any other group. That means interoperability, even among devices made by manufacturers using the same silicon isn't assured.
The worst part, in my estimation, is that this generation of MIMO technology isn't what the final 802.11n specification will look like. So purchasing MIMO today except for specific applications in which you need substantially higher throughput and range from a single device over interoperable, certified 802.11g means you're buying a dead-end device.
802.11n might achieve speeds of several hundred megabytes per second, and there's is practically a total certainty that the final 802.11n won't be just a firmware upgrade, but rather a difference in both hardware and silicon compared to today's MIMO devices.