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Linksys and NetGear expand their 802.11n line-up: Linksys has added two inexpensive 802.11n home routers for 2.4 GHz connections. The WRT160N at $100 has 10/100 Mbps Ethernet and no external antennas in a new form factor; the $130 WRT310N upgrades to gigabit Ethernet. They also introduced inexpensive dual-band add-on adapters: the WEC600N ($80) for ExpressCard slots, the WUSB600N ($80) for USB, and the WGA600N ($90), an adapter for gaming systems like the Xbox. This is a very nice price drop to add both 2.4 GHz and 5 GHz 802.11n to older computers.
NetGear, meanwhile, has expanded its line to include the WNDR3300, a $130 dual-band, 8-antenna router with a 4-port 10/100 Mbps Ethernet switch, and the WNDR3500 ($160), which is 5 GHz only and has a 5-port gigabit Ethernet switch. A $230 kit comprises two 5 GHz 802.11n access point/bridges (WNHDE111, $130 by itself) as a paired set for gaming, streaming video in HD, or other bridging purposes. NetGear also offers up a dual-band USB adapter (WNDA3100, $100). PC Magazine noted there was no ExpressCard or PC Card adapter mentioned at the show.
Chipmaker Marvell will offer 3 spatial streams in new chips, with 450 Mbps raw speed: Each spatial stream in 802.11n can hit 150 Mbps raw symbol rate when combined with 40 MHz channels. The 802.11n spec requires at least two spatial streams—two unique paths through space that reuse frequencies—but three or four are also possible, and it was predicted that 2008 would see a four-spatial stream product by year’s end with a raw 600 Mbps rate.
Marvell fires the first shot over the bow with this announcement, pre-Consumer Electronics Show (CES), tha they will ship a TopDog chipset at 450 Mbps. It won’t ship until second quarter 2008.
Expect more announcements as CES nears or at the show itself.
Broadcom will offer 802.11n on a single chip with a 50-percent power savings: The announcement, planned for tomorrow, was revealed early by Techworld this afternoon. Broadcom said the chip handles 2.4 GHz and 5 GHz, can fit on a PCI Express Mini Card for laptops, routers, and consumer electronics, and will be in products by early 2008. They’ve reduced the cost of manufacture for a module by 40 percent with this new chip, and reduced its footprint by 50 percent, in addition to losing half the power requirements.
The dual-band part is particularly exciting, because it means that 5 GHz could become a standard expectation in adapters, allowing for the far better streaming and data transfer possible in that band.
QuckerTek has released several cards and adapters for Macintosh computers for 802.11n, and even 802.11g: The add-on firm has an increasingly large array of 802.11n upgrades in their nQuicky series, prices for which were recently dropped as new items appeared. All of these upgrades in card or dongle form are 2.4 GHz only; their upgrade kits are dual 2.4 GHz/ 5 GHz capable.
Offerings include CardBus ($59) and PCI cards ($99) for PowerPC Macs (10.3.9 or later); a high-powered USB dongle ($150) for all Macs running 10.3.9 or later; and a lower-powered USB dongle called the nNano ($60), which works with 10.3.0 or later. The company also offers upgrade kits and professional mail-in installations of new cards for any Intel Mac mini (no model of which features 802.11n), and the Intel Core Duo models of MacBook, MacBook Pro, and iMac that lacked the 802.11n option.
The firm also has a $50 USB 802.11b/g/n dongle that’s a great help for owners of older Macs that were otherwise limited to 802.11b via the now-unavailable-and-expensive-when-purchased-used AirPort Card.
Apple slips in 1000 Mbps Ethernet in its Wi-Fi router: Apple quietly upgraded its Draft N-based AirPort Extreme Base Station to full gigabit Ethernet support across its three LAN and one WAN ports last week. I’ve had a chance to test the new unit, and while I can’t post results (a print magazine has dibs), let me just say that the new benchmarks are far better than the old ones.
The first release of Apple’s Draft N base station was rather marvelous for its inclusion of a USB port to share multiple printers and hard drives; the company’s decision to have both 2.4 GHz and 5 GHz radios inside; and the fact that Macs had been shipping with 802.11n inside, requiring just an enabler, released with the base station, to upgrade their performance. My primary complaint, however, was the mismatch between the company’s widespread inclusion of GigE in most of its models long before the competition. With the drop in cost in GigE switches, it seemed odd for Apple to release a unit that was designed for homes and small offices that would underperform a $35 Ethernet switch.
I also suspected that the overall performance of the 802.11n draft that Apple is using was constricted due to internal Ethernet limits. In my testing for a review in Macworld, I was able to top 90 Mbps in Wi-Fi to Ethernet and Wi-Fi to Wi-Fi transfers. But Ethernet-to-Ethernet data was limited to just over 90 Mbps as well. Apple says that their new gigabit Ethernet base station is up to 50 percent faster for wireless-to-wired links, which would put it closer to 150 Mbps, a speed achieved on other GigE-based Draft N routers. My testing shows that these numbers are accurate.
When testing the base station in February, I discovered that with NAT enabled to share access from an incoming WAN link, performance was restricted to about 30 Mbps from wireles LAN to LAN and 60 Mbps from wired LAN to WAN. Apple confirmed this was a bug that was due to performance issues in their NAT stack. Apple wasn’t able to tell me if this limitation has been fixed, but in testing, I found it much improved.
(This bug emerges in only two edge cases: Where a broadband connection exceeds 30 Mbps, which is true for some fiber and cable customers; or where a corporate or office LAN isn’t supplying addresses to the computers connected via the AirPort Extreme. If NAT is turned off, the AirPort gateway has no performance limitations.)
The price for the AirPort Extreme Base Station with Draft N remains $179.
Morrisville State College could be the first large-scale buildout of Draft N equipment for a wide-area wireless LAN: They plan to have 900 Meru APs with 802.11n installed by September for the 1,800 students. Each node is $1,500 at retail—holy smokes! That’s the price of early deployments. Meru’s regular 802.11g nodes run half that at retail.
I have a problem with the radio count noted in the article. Two radios in the AP are described, one each for 2.4 GHz and 5 GHz. Incoming students will receive Lenovo ThinkPad’s with 802.11n installed and preset to the 5 GHz band. However, the 2.4 GHz band is described as being broken into a 20 MHz 802.11b/g dedicated channel and a 40 MHz 802.11n channel. That’s not exactly how a single radio functions. You’d need two separate 2.4 GHz radios for that purpose. And most of the 802.11n experts and chipmakers I’ve spoken to don’t recommend running 802.11n in this fashion.
The college was still using a 2 Mpbs 1999 era Raytheon Raylink system for their network! There’s another New York college, Mount Saint Mary, that made a leap from RangeLAN systems in the late 90s to 802.11a back in 2002 (!!) using Proxim gear. They were way ahead of their time, but they also had Morrisville’s advantage: they were helping students get the right gear at a decent price (or rolled into tuition).
Craig Mathias of Farpoint has been one of the most sensible analysts on the subject of 802.11n and Wi-Fi: He’s now happy with the direction of the market, and things that 802.11n has become mature in a non-traditional sense. Most of the elements have been in products for almost four years, he writes, and the Wi-Fi Alliance’s certification process will put the icing on the cake for compatibility. With corporate products already announced, that puts a faster track on enterprise adoption, too. He thinks adoption in the consumer and corporate space will happen sooner than later.
The Wi-Fi Alliance said today it would offer a two-phase plan to keep 802.11n’s innovation moving along: With the next potential draft approval of the faster wireless data standard from engineering standards group IEEE’s Task Group N looking like it won’t appear until March 2007, the Wi-Fi Alliance has chosen to step in to stabilize the market. The first phase of certification will confirm compliance to what they expect will be Draft 2.0 in March, the next letter ballot in which Task Group N voters agree to an extensive set of changes to Draft 1.0. The compliance will be coupled with interoperability testing, so that devices labeled with their phase 1 branding—yet to be determined—will work together at the right speeds.
The second phase will be tied to a ratified standard, which may come by spring 2008. Ratification usually takes up to six months after final technical details are decided on and approved within a task group, so the standard will likely be gelled by fall 2007. Wi-Fi Alliance managing director Frank Hanzlik said in an interview today that should the March 2007 meeting not produce another draft, the alliance would assemble the closest possible set of agreed-on ideas to produce their certification standard. (The news was scheduled to be released tomorrow morning; News.com broke the embargo this evening.)
Products that comply with phase 1 certification for draft 802.11n could be on the market—through firmware upgrades or new hardware releases—by June 2007, but it’s likely that devices that start to hit the market by early 2007 will more and more closely conform with what will be certified. “We actually are doing a lot of formal interoperability testing within the alliance with pre-standard products,” said Hanzlik, and this ongoing work should reduce the time between the draft’s approval and certification approval. (The alliance has opened more worldwide testing labs in recent months, too, which should distribute its certification work for faster completion.)
Phase 1 products aren’t guaranteed to be forward-compatible with phase 2 products. “The forward-compatibility part is certainly too hard to call at this point; it’s not anything that the alliance is committing to,” Hanzlik said. However, they are stressing that compatibility among the phase 1 and 2 products would be highly stressed.
Phase 1 products will almost certainly have none of the optional elements for 802.11n, such as larger antenna arrays that produce higher throughputs. Some of these optional elements remain points of discussion, and will be less settled until further drafts are developed. Another major issue outstanding is the manner by which 802.11n devices will interact with legacy adapters and legacy networks, whether on the same Wi-Fi network, same Wi-Fi channel, or on adjacent Wi-Fi channels. That is expected to be resolved for the next letter-ballotted draft, which should be Draft 2.0.
This intermediate approach to 802.11n certification echoes the earlier interim security measure, Wi-Fi Protected Access (WPA), that the alliance put into place when the work on 802.11i lingered far longer than the market and manufacturers would tolerate, with the failure of Wired Equivalent Privacy (WEP) as a reliable link encryption method. WPA was available a year before 802.11i’s final ratification, and stabilized the security concerns of the market. The later WPA2, which included the strong AES encryption method, entered the industry with relative seamlessness.
Of course, WPA had more to do with retrofitting a security model to work on older devices without leaving newer devices with less protection, and was a good-enough security system; WPA2 almost serves a different market, in which government-grade encryption algorithms are required and fast handoff for authentication, mobile devices—like VoWLAN handsets—is critical.
With 802.11n, the standard has to work on the lowliest to most sophisticated device, and there’s a lot of hardwiring in silicon that can’t be fixed later, so the standard has to be right when devices are released. That’s been one of my primary objections to Draft N gear.
I have consistently said that you should not buy Draft N gear because there are significant advantages for most users. Buying MIMO gateways makes a lot of sense if you want better 802.11g speeds over greater areas. That technology is now relatively mature, relatively compatible, and relatively cheap. Draft N devices are quite expensive (Atheros aims to fix that by year’s end), don’t seem to deliver range and speed in testing (see this latest PC World showdown), and have no guarantee of full upgradability when the final 802.11n standard is delivered. (Intel said today they’d include Draft N support in their Santa Rosa platform in the first half of 2007, but Intel is on the board of the Wi-Fi Alliance, and thus knew this certification was coming when they made this statement.)
This process set up by the Wi-Fi Alliance answers my concerns.
First, with 802.11n’s ratification pushed back nearly a year from the expectation just a few months ago, there’s now a reason to bring today’s capabilities into today’s equipment. When ratification was just a few months away, having an entire generation of equipment that would be potentially incapable of forward compatibility or upgrade seemed ridiculous. Now, it’s a reasonable market choice given a 12-to-18-month lifespan for the right kind of user. (The equipment will obviously continue to work after the ratification, too, and have its own value as it will retain interoperability and other benefits that current Draft N devices can’t guarantee.)
Second, the Wi-Fi Alliance is waiting for Draft 2.0 or its equivalent. This allows a host of compromises to be made in the year between Draft 1.0 and 2.0, and technical problems to be solved. There should be an ocean of difference from Draft 1.0 to 2.0 in terms of basic problems being solved. Today’s Draft N devices promise compliance to a draft that will be superceded, and offer no hardware upgrade promise when and if that happens if firmware upgrades fail to suffice.
Third, the alliance will offer a brand that I confirmed with Hanzlik will be clearly differentiated in phase 1 and 2. This won’t offer consumers or businesses any implicit promise about forward compatibility. This reduces confusion in the marketplace and provides a clear message to equipment buyers that they are buying gear that may be superceded later, but has value now.
Fourth, the interoperability and conformance testing by the Wi-Fi Alliance will smooth out the rough spots in using devices from different manufacturers together. Some early equipment plays very poorly with its friends (similar devices from other makers) and neighbors (nearby networks). The alliance’s process has worked in the past.
So, I can’t say right now, go out and buy Phase One gear, because it has no name and doesn’t exist. But I will predict with some degree of certainty that devices that start shipping in late winter 2007 will likely offer enough carrots for those who need higher performance or greater area networks to start thinking about purchase, and what’s for sale by June 2007 (and certified) will be good investments in the next generation of Wi-Fi.
On the main Wi-Fi Networking News site today, I explain why you shouldn’t buy Draft N gear: The Draft N devices lack a promise of forward compatibility (they’re likely to be upgradable, but there’s no guarantee from manufacturers), cost too much, and will require frequent firmware upgrades. Why buy now? See my editorial for more on the issue.
The company joins the early parade of equipment makers: Linksys didn’t provide estimates of net throughput, but is clearly offering the 300 Mbps (raw) version of 802.11n in its draft form, with limited throughput on the new router due to a 10/100 Mbps Ethernet switch which can’t carry the maximum possible data. The WRT300N will run $150; the complementary PC Card is $120. While the company said products are shipping today via Bestbuy.com, TG Daily notes that there’s a 1-2 week delay noted on Best Buy’s site.
In the off-the-wall Ruckus Room, in which the company speaks in something approaching a real voice, they maintain that 802.11n buys you bandwidth not QoS: And they’re right, of course. They have a real nice business in providing hardware and algorithms that make IPTV (that’s video over IP) work reliably using multiple antennas and beamforming. 802.11n adds a standardized method of having multiple radios split data into simultaneous but unique streams that follow different reflective paths at the same time, which is called spatial multiplexing. It’s a way of reusing the same spectrum by sorting out signals passing through the same physical space.
Ruckus notes that this might improve bandwidth but it doesn’t do anything for ensuring that streaming video works without a hiccup. They don’t mention 802.11e, which offers prioritization of streaming video packets, in this context, but 802.11e won’t necessarily work as expected within 802.11n. Why? Because 802.11e provides a way of tagging packets to ensure that some get more precedence over others, but it doesn’t ensure that the optimal methods are used to move data so that it arrives with the least amount of lost packets or least retransmission (depending on protocol).
With video, it’s not just important that packets arrive with priority over others, but that there are no gaps in arrival longer than the buffered interval stored on the receiving device if you want to have clean streaming and avoid artifacts. Ruckus claims their technology can overlay 802.11n to provide this. It’s definitely the next big wave, with many companies talking about 802.11n as having the bandwidth for multiple simultaneous high-definition video streams.
Of course, there’s still the other IP (intellectual property) part of this equation. While specific paired devices, such as those used in Windows Media Edition systems, can move video content around a network, there’s no generic accepted approach for taking high-def off the air or off future high-def DVDs (BluRay or HD-DVD) and streaming them to other devices. That’s an application-layer problem that involves lawyers, but it’s got to be solved if the vision of HD zooming around a home is to be achieved beyond specialized home electronics.
Buffalo vies with NetGear over bragging rights: Buffalo announced today that its three Broadcom-based draft 802.11n networking devices are the first to reach retailers with its AirStation Nfini. The company is selling a gateway, PC Card, and PCI Card designed to operate at speeds of up to 100 Mbps. While the standard supports a raw rate of about 300 Mbps—faster using some proprietary Broadcom tricks—the device has 10/100 Mpbs Ethernet and internally can’t support faster rates over the airlink.
In an interview earlier in the week, Morikazu Sano, Buffalo’s senior vice president of global marketing, said that the cost of adding gigabit Ethernet was still too high for a general market product of this sort, and that as costs dropped the faster switch speed would be added. “Instead of being first to announce the product, we wanted to be the first to ship the product,” said Sano. The router is $179; the adapters, $129 each.
Sano was blunter than most manufacturers about “futureproofing”: whether these Draft N devices would be guaranteed by Buffalo to be upgradable via firmware or equipment swap to the final 802.11n standard. Sano said, “We cannot promise that,” and that “I don’t think it’s right to make that announcement.” Buffalo expects firmware upgradability, but believes that its chip supplier, Broadcom, will have to commit first to that guarantee before Buffalo as a manufacturer can make the same claim.
Early adopters are expected to snap up the Nfiniti because of its ability to deliver somewhere north of four times the throughput of plain 802.11g and about two to three times the throughput of enhanced 802.11g using frame bursting and other techniques. Sano suggested that gamers, graphic designers, and video/audio mixers would probably be among their first customers. With more powerful laptops, it’s more likely that a user would want to maintain their untethered status while still having high-speed network access.
Meanwhile, NetGear said today that they not only shipped their gigabit Draft N gear (also using Broadcom chips) to retailers days ago, but their 10/100 Mbps line and related devices are now in the supply channel.
For the record, I can’t find any etailer, including both Buffalo and NetGear’s own online stores, that list any of this gear as available for immediate shipment. Only Buy.com lists NetGear’s gigabit kit and that with a 1-2 week delay for receipt.
Marvell today noted that D-Link’s Draft N products, scheduled to ship later this month, will use Marvell chips. Marvell calls its chip line TopDog.
NetGear announced this morning it has product moving to retail channels with draft 802.11n chips: The NetGear RangeMax Next product line is shipping to retailers, and available soon. NetGear gets bragging rights (as Belkin did with Pre-N) for the first products to market with draft 802.11n built in. The draft standard (see previous item) may require firmware changes or more drastic changes depending on whom you ask.
NetGear claims up to 300 Mbps performance with their line of products, which should mean 150 Mbps to 200 Mpbs of actual throughput. They’ll offer both gigabit switched and 10/100 Mbps switched gateways and CardBus cards. They also have an DSL modem, PCI Card, and plain access point. These products use chipsets from Marvell.
The gigabit kit (card and gateway) lists for $349, staggering, but the only option for that kind of wireless performance; the gateway and CardBus adapter are $249 and $129 separately. The 10/100 Mbps switched gateway lists for $179, the DSL device is $249, the regular CardBus adapter is $129 (oddly priced identically with the gigabit card), the PCI Card is $129, and the access point $249.
D-Link may have the first draft 802.11n products on the market later this month: The draft chipsets incorporate what’s settled in the featureset as it moves its way through the IEEE task group process. Airgo claims there’s a lot of necessary work to be done; other chipmakers say minor tweaks addressable in firmware are all that’s needed. D-Link will offer a router ($160), PCI Card ($120), and CardBus ($100).
The devices use Atheros chips and promise 100 Mbps throughput. The article notes that 10/100 Mbps Ethernet is included, which will actually reduce performance on the high end, as 802.11n should outperform Ethernet, which runs at 80 Mbps subtracting overhead.
TG Daily reports that other announcements on 802.11n are expected at the Interop trade show next month.
Update: Scratch that! NetGear said this morning they are shipping their own 802.11n gear today.
The company has shown live demonstrations of HDTV streaming video using its upcoming WLANPlus chipset: The firm was pushing the home entertainment aspect of 802.11n, combining quality of service—which prioritizes some data over other data—and high-bandwidth with long range to stream multiple high-definition signals. The press release quotes reliable research firm ABI noting a 10fold expected increase of Wi-Fi embedded in consumer electronics from about seven million devices in 2004 to 70 million in 2007. Metalink has a partnership with Haier, the giant Chinese CE maker.
The company claims the ability to offer multiple HD streams within a radius of 100 feet. They mention channel bonding and 5 GHz, which indicates a smart use of unused frequencies that, even with poorer propagation characteristics—5 GHz photons don’t penetrate as far with the same input power as 2.4 GHz photons—can provide a good range.
Large-scale Wi-Fi network operators in corporate and academic worlds bearish on N in short-term: These kinds of users need to see real improvements and good-neighbor operations before adopting 802.11n, as it doesn’t offer any real advantages in the short-term over their current networks.
The IT director at Mount Saint Mary College in Newburgh, New York, is quoted as wanting to see test results. They’re an interesting case. I spoke to them three years ago because they were a very early WLAN deployer using RangeLAN (2 Mbps) equipment in the late 1990s. They moved from RangeLAN to 802.11a because it offered much higher speeds and less interference even though it seemed a strange move at the time and requiring users to purchase 802.11a or a/g cards for use on the campus network.
Paul Callahan updates his report on 802.11n silicon: He had earlier noted credible first-person reports that Marvell’s upcoming 802.11n chips were performing quite poorly in early testing. Marvell rebutted that to him, stating that they have chips in production (not just sampling or small quantities for testing), that performance is fine, and that consumer devices like gateways will sport the chips—not just specialized products.
Proof is in the pudding, of course, but the pudding should be out of the oven and in the fridge within a few weeks.
The IEEE approved draft 1.0 of 802.11n yesterday: The IEEE voted in January to accept a proposal—largely that of the Enhanced Wireless Consortium with some changes—as a pre-1.0 draft. That near-unanimous vote was the first step in finalizing 802.11n, which has been under discussion for years and which appeared to be heading to a deadlock. The EWC proposal was quietly built by four chipmakers—Atheros, Broadcom, Intel, and Marvell—and then sold back into a joint proposal group that was trying to harmonize competing efforts.
That work paid off given the quick approval of Draft 1.0. This first fully numbered draft had only very minor technical changes from the proposal that was accepted as the 0.1 draft in January, according to Atheros’s chief technology officer Bill McFarland. In an interview this morning, McFarland said that changes were primarily to conform to IEEE editorial style, including adding detailed appendixes and some clarifying text. “The draft was evaluated by the group as being complete, technically very sound, and in shape where it could potentially be the exact final standard,” McFarland said. That doesn’t mean it will be adopted as is—that’s very unlikely—but it has the form and detail of a final draft.
McFarland said that the proposal will now be sent out for balloting among 802.11 Working Group members for a 40-day period. Ballots will vote up or down on accepting this draft, and will bring back comments and requests for changes. In the May meeting, those changes will be discussed, and some will be adopted and others not. If all goes well, a re-ballot will happen following a similar course. In July, a final draft could win the day, which would then go on to a group of experts at a higher IEEE level who typically approve drafts—by the time they’ve reached this point, most technical and harmonization issues across 802 (networks) and 802.11 (wireless networks) have been settled.
Meanwhile, manufacturers will probably start firing up the silicon ovens. McFarland said that Atheros was already in sampling, and it was very encouraging that “In getting to this 1.0 draft very few technical changes needed to be made.” There is a very low risk, he said, of significant changes being made before a final draft is accepted that would require changes in silicon.
Inertia will set in, too, because so many chipmakers already are sampling or showing 802.11n designs to their customers. “As time goes on, all the major silicon providers have begun work on it so they prefer more and more there not be changes,” McFarland said.
Atheros is sampling draft 802.11n chips now. “We expect that you’ll be able to see products on the store shelves certainly by the middle of this year implementing this 1.0 draft,” McFarland said. Changes to the spec would be handled through firmware upgrades.
For some reason, NetGear decided to issue a press release about its upcoming 802.11n products: They claim they will have a 600 Mbps (raw) 802.11n device out in the first half of 2006 that will meet the in-progress spec, TechWorld reports. The 600 Mbps rate is raw speed using the maximum number of spatial streams, a 40 MHz-wide channel, and the largest antenna matrix. This should top 300 Mbps of real throughput.
The press release doesn’t say NetGear guarantees that their draft 802.11n devices will be upgradable to the full version. Understatement by me follows: One would expect forward compatibility assurances. However, companies are reluctant to state such.
Can we have firms raise their hands: Who among you is willing to say that any draft 802.11n equipment shipped will be replaced if necessary to provide full, certifiable 802.11n compliance?
In all the discussion of 802.11n, the notion of using it for outdoor spaces as been little explored: 802.11n is an indoor specification, let’s face it. It achieves its potential rates (in the proposal accepted recently) through improvements to the MAC’s efficiency, RF upgrades, spatial multiplexing, and double-wide channels.
MAC efficiency could be a big improvement, in that the Media Access Control components deal with the fiddly parts of packaging data into frames (or removing them), error correction, and handling source and destination issues. Improvements to the MAC layer will help throughput regardless of other elements. Likewise, fixing radio frequency (RF) deficiencies in 802.11g and adding better characteristics will improve the quality of transmissions, too.
But when you get into the remaining two elements, there’s where the problem creeps in. Spatial multiplexing is one of the key advantages of multiple-in, multiple-out (MIMO) antennas. Using multipath reflection, a MIMO device—such as any future 802.11n radio—can produce multiple data streams that contains different information passing over the same frequencies. (They can also duplicate the same data for redundancy improving the fidelity of reception.)
In outdoor spaces, there isn’t enough multipath reflection close enough to a transmitter to provide that advantage. I’ll be curious whether a concrete canyon would work, say in downtown Manhattan, but wide open spaces won’t.
The double-wide channels, which will be 40 MHz wide instead of the normal 20 MHz for the 802.11 family, have a similar problem. In current thinking, 40 MHz can be used only if the airspace is clear. (Airgo’s early implementation of this is causing it some black eyes for neighborliness, although they have already stated some elements will be changed via firmware upgrades.)
In typical outdoor environments where using Wi-Fi would make sense, it is unlikely that any two adjacent channels would have no signal present.
The conclusion? The 200 Mbps to 600 Mbps possible in 802.11n will probably appear more like 40 to 50 Mbps of actual throughput for outdoor installations; indoors, 100 to 300 Mbps will certainly be achievable, however.