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Recent Entries

Meraki Goes All In: 802.11n Triple Radio Outdoor Node
Buffalo Allowed to Sell Wireless in U.S.
Quantenna: Radical New Design or Great PR?
Linksys WRT610N Review
Apple's AirPort Express Offers N at $99
Wi-Fi Alliance Starts Testing Draft N
Atheros Expands Draft N Options with USB, Routers
Wi-Fi Alliance Gives Draft N Certification Details
First Draft N 2.0 Firmware Shipped by D-Link
Gefen: HDMI over UWB; Belkin: USB over 802.11n

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Recently in 802.11n Category

February 24, 2009

Meraki Goes All In: 802.11n Triple Radio Outdoor Node

By Glenn Fleishman

Meraki has decided they're a grown-up company, after all: Meraki started out as the little guy, with tiny $50 nodes that would self-organize into a mesh Wi-Fi network. Even as the company grew out of its origins, it still focused largely on indoor applications, where outdoor uses were an adjunct. Their new MR58, a 5 GHz triple-radio 802.11n ruggedized weatherproof outdoor node changes that entirely.

The $1,499 (list) unit, which meshes with all the existing gear and includes the license for Meraki's required software-as-a-service hosted management system, can go omnidirectional or directional on each of the three radios as separate systems. The company sees the unit as being a way to link locations (they claim 1 to 20 km with appropriate directional antennas), and provide front-end access in public places.

The company sells into several markets, including hotels and motels, apartment buildings, academic campuses, and hotzones. It doesn't emphasize corporate customers, although Meraki added WPA2 Enterprise authentication in a recent back-end update.

The gear Meraki is selling could be used for cities--the company has some such installations in towns--but the design is intended to extend Meraki's existing ecosystem from tiny indoor wall warts up to outdoor AC and solar-powered single-radio models.

The MR58 is 802.1af Power over Ethernet compliant, sucking down 8 watts at most, the firm's founder told me. This means a single Ethernet run to a roof can power the MR58; no AC outlets required.

You can get the full scoop in my coverage at Ars Technica.

Posted by Glenn Fleishman at 8:51 AM | Permanent Link | Categories: 802.11n, Hardware, Metro-Scale Networks | No Comments | No TrackBacks

December 3, 2008

Buffalo Allowed to Sell Wireless in U.S.

By Glenn Fleishman

Buffalo Technology has had an injunction lifted in its ongoing patent litigation with Australia's CSIRO technology agency: Buffalo was unable to sell Wi-Fi equipment in the U.S. since a permanent injunction was put in place in June 2007 following their 2006 loss in a lawsuit. CSIRO has a patent that they argue covers aspects of OFDM in 802.11a/g. CSIRO sued Buffalo after the Japanese equipment maker declined to pay royalties.

The injunction prevented Buffalo from selling gear that it offers in Japan and elsewhere in the world during the huge expansion of Draft N sales. This likely caused tens of millions of dollars of lost revenue, if not more. Buffalo was formerly mentioned in a single breath with D-Link, Linksys, and NetGear. (Linksys, as a division of Cisco, already pays CSIRO license fees: Cisco agreed to honor CSIRO's patent assertion because of a purchase of an Australian firm a few years ago.)

WZR-AG300NH_front-lg.jpgBuffalo can now sell Wi-Fi gear in the U.S. due to winning a narrow appeal in October that sent the case back to a lower court to resolve an issue. The company could still be liable for damages and other fees if the lower court finds for CSIRO and higher courts agree.

Orthogonal Frequency Division Multiplexing allows a single Wi-Fi channel to be subdivided into a smaller number of channels, improving performance in reflective environments and adding robustness against interference. It's also used in WiMax, LTE, and other standards. This could mean CSIRO would pursue makers of other technology eventually as well.

CSIRO has never given any sign of asking for predatory royalty rates, but several firms have countersued, including Intel, Dell, and Microsoft. Those cases are still in litigation, as far as I can tell.

Posted by Glenn Fleishman at 4:32 PM | Permanent Link | Categories: 802.11n, Legal | No Comments

October 14, 2008

Quantenna: Radical New Design or Great PR?

By Glenn Fleishman

The folks at Quantenna made a splash with their "1 Gbps" Wi-Fi announcement today: Venture-backed chipmaker Quantenna says that they have a tiny chip that should make it easier and cheaper to push high throughput Wi-Fi around a home using wall-outlet adapters. The company claims 450 Mbps of throughput from the highest-end Draft N standard (600 Mbps raw), and that it has a 1 Gbps wireless offering that uses multiple bands and channels to achieve throughput. There's not enough detail to know how proprietary that is, or if it's a form of channel bonding.

Quantenna announced three chipsets and a reference design: simultaneous dual band at raw rates up to 1 Gbps, 5 GHz at up to 600 Mbps, and 2.4 GHz at up to 450 Mbps. The reference design is for a compact wall outlet Wi-Fi extender.

The company said it's using a proprietary version of the 802.11s mesh protocol to allow devices to interact with each other. Quantenna's focus appears to be on spreading signals across a house, such as with streaming high-definition, where lots of bandwidth will be needed as telcos, satellite operators, and cable firms deliver HDTV into homes today, but plan much more in the future. Storing HD and then being able to have multiple live streams sent among devices is apparently the wet dream of those involved in home entertainment.

You can be clever about pushing HD around a home (like Ruckus) or brute force it by flooding an area with high throughput like Quantenna, which isn't a bad strategy, but it's an interesting one. The fact is that there are already market solutions that don't require 450 Mbps of net throughput. The segment they're looking at seems too well developed and small for them to capture a sizeable chunk when products based on their design are released in mid-2009. And as a startup, their ability to sign deals with firms that sometimes take 1 to 2 years to negotiate and sign makes me wonder; their investors might be brokering those deals to make them conclude faster.

Small, integrated chips make a big splash because they reduce the battery drain on mobile devices, allow the use of these chips in handhelds, and can dramatically drop the cost of manufacture both through a reduced bill of materials and reduced assembly costs. Quantenna told several sources that they expect to charge $20 for a single-band chipset and $40 for a dual-band chipset in quantity. For chipmakers these days, that can mean from 100,000 to 1m before the price drop happens. (It used to mean much more, but efficiencies have improved in smaller lots of chipmaking, apparently.)

I've followed chip announcements in the Wi-Fi space for years, and small startups that have unique offerings tend to either get swallowed up in short order (Airgo into Qualcomm) or disappear (the very promising Engim\). Atheros, Broadcom, Qualcomm, Texas Instruments, Marvell, CSR, and a few others own the market, and that's just how that is. Chipmakers in this industry segment needs millions and then tens of millions of sales to make it possible to recover their R&D costs while sinking money into future R&D for the inevitable next generation.

(Airgo, I might note, was sucked into Qualcomm and sunk without a trace, although it's likely their patents were part of what was of interest; their approach to building MIMO systems was probably integrated into other product lines and multi-standard chips.)

Posted by Glenn Fleishman at 3:48 PM | Permanent Link | Categories: 802.11n, Chips, Future | No Comments

September 16, 2008

Linksys WRT610N Review

By Glenn Fleishman

My review of the Linksys WRT610N at Macworld: The router works quite well at handling Wi-Fi and other functions, but is terrible at working with Mac OS X, one of the advertised features of the product. The WRT610N is a revised design of the previous simultaneous dual-band (2.4/5 GHz) Draft N WRT600N model which had far worse problems.

Linksys addressed many of my concerns with that previous device. The 610N can mount a drive and share it via SMB and FTP, have two full-speed connections running over both bands without skipping a beat, and supports several methods of getting the one-click WPS (Wi-Fi Protected Setup) to work. Read the review for all the details, but I can't recommend this router to Mac users with any needs beyond basic networking; I'm perfectly happy to give it a full thumbs-up for Windows XP and Vista users, however.


WPS is a particular mess, by the way. Linksys has four somewhat distinct methods of using WPS to enable a password-free encrypted connection between a client and a base station: a button on the front that, when pressed, turns on WPS; and three modes (one of them similar to that button) accessible via their Web configuration software. One option is to get the base station to create a short PIN that's then entered on the client system as an out-of-band confirmation that there's no man in the middle.

Apple, by contrast, has a single way of joining a WPS-offering base station: it displays the network's name in bold. Select the network, and Mac OS X displays a key code that needs to be entered on the base station. But the WRT610N can't handle that option. If you put the WRT610N into a mode in which Apple can spot the device as offering a WPS handshake, you can't enter the code into the Linksys router!

This shows that there's still rough edges in the WPS protocol that two of the highest-selling makers of Wi-Fi gear can manage to not mesh up their respective options. (Apple declined to comment for my Macworld story; Linksys confirmed the lack of compatibility, but put the burden on Apple's doorstep.)

Posted by Glenn Fleishman at 9:27 AM | Permanent Link | Categories: 802.11n, Hardware | No Comments

March 18, 2008

Apple's AirPort Express Offers N at $99

By Glenn Fleishman

Apple isn't the only firm to offer inexpensive 802.11n, but their revised AirPort Express has a few extras: You can buy Draft N from other companies for under $100, but I'd point out that the new AirPort Express compact base station differs from those items. The new model, announced yesterday, is nearly identical to the one that Apple's been selling since 2004. Unlike other inexpensive N base stations, it has a USB port to share one printer (Windows/Mac OS X), an audio output port for streaming from iTunes or via Rogue Amoeba's AirFoil (Mac/Windows, analog/digital optical), and is dual band, supporting 2.4 GHz and 5 GHz 802.11a, b, g, and n.

airportexpress2.jpgThe base station is compact, small enough for travel, with an integral 2-prong plug that can be directly hung from a wall socket, or removed to replace with a several-foot-long 3-prong cord; the extension cord is part of a $39 audio extension kit, and not sold separately from that kit.

While Linksys, D-Link, and others have sub-$100 802.11n base stations, there are differences. The main one is a detriment to the AirPort Express: it has just a single 10/100 Mbps Ethernet jack. That means it's appropriate to directly connect to a larger network via Ethernet, where addresses are assigned out by another part of the network, or it can be plugged directly into a broadband modem and assign addresses out via DHCP and NAT (or a pool of routable addresses).

The Linksys WRT100 (about $80) isn't Wi-Fi certified (yet) for Draft N, while the D-Link DIR-615 (about $60) is, as is the AirPort Express (although the Express isn't yet listed in the Wi-Fi Alliance's database). Both the Linksys and D-Link units have 4-port 10/100 Mbps Ethernet switches along with a 10/100 Mbps WAN Ethernet port. Both are single-band (2.4 GHz), omit USB sharing, and have no audio streaming. (If you know of better sub-$100 models to compare the AirPort Express to, drop a note in the comments.)

It's worth calling out Airfoil, mentioned above, a package from Rogue Amoeba for Mac OS X and Windows that lets you manage where audio goes over your network. Using Airfoil and its included Airfoil Speakers software, you can choose to play audio on one computer and target it to other computers on your network, as well as AirPort Express base stations and the Apple TV media adapter (using Apple's AirTunes streaming protocol). Without Airfoil, you're limited to iTunes streaming under Mac OS X and Windows to an AirPort Express or Apple TV.

I've written a book about 802.11n and Apple's AirPort networking, Take Control of Your 802.11n AirPort Extreme Network, that covers all the issues in setting up secure networks using both Macs and Windows XP/Vista. You can buy the title with at a 30-percent discount ($7 instead of $10) by following the link or using coupon code CPN71005WNN at checkout.

Posted by Glenn Fleishman at 11:52 AM | Permanent Link | Categories: 802.11n, Home, Road Warrior | 2 Comments

June 25, 2007

Wi-Fi Alliance Starts Testing Draft N

By Glenn Fleishman

They promised June--they delivered June--but I was expecting, well, certified devices, not certification testing: The Wi-Fi Alliance has been asserting since last year that they would have a certification program in place during second quarter 2007 to test Draft N (early 802.11n equipment) devices against Draft 2.0, an expected milestone in IEEE work on the standard. Today's press release shows they met the mark, but I had naively assumed that there would certified devices on the market in June, too. Alas, not so. The certification program has begun, and new firmware and equipment will be out this summer. How soon, it's unclear.

The Draft 2.0 compliant firmware that manufacturers have promised, and that chipmakers apparently completed months ago, will likely not be released for the majority of Wi-Fi devices with Draft N until certification is finished for that device in case things need to be fixed.

Draft 2.0 should improve interoperability among devices, and it adds three separate protection mechanism for the 2.4 GHz band to prevent N from using more spectrum than a comparable G device in the presence of other networks. In 5 GHz, where there's much more "room," only two of those mechanisms are needed, because interference is much less likely and easier to solve. (See "How Draft N Makes Nice with Neighbors," an article I wrote after interviewing chipmakers that appeared 2007-02-16.)

Update: The Wi-Fi Alliance told me that certification could take as little as "hours," and that 20 products were booked for testing on the first day of certification. That's fine, but I'm interested in the cycle from certification to firmware release. I had really expected that certification results along with updated firmware would occur within the quarter, but I am just too darned optimistic.

Tim Higgins, meanwhile, is not very happy with his testing of pre-certification Draft 2.0 updates from D-Link. They don't conform to his reasonable interpretation of the co-existence mechanisms for N and earlier B/G devices in the same frequency ranges.

Posted by Glenn Fleishman at 12:51 PM | Permanent Link | Categories: 802.11n | No Comments | No TrackBacks

May 21, 2007

Atheros Expands Draft N Options with USB, Routers

By Glenn Fleishman

Atheros announces fast, two-radio gateway, USB adapter, revised single-radio gateway: Chipmaker Atheros announced today that it has dramatically expanded the variety of its Draft N reference designs to include the smallest form factor USB 2.0 after-market adapter and two new routers, including a dual-radio access point that can achieve 400 Mbps in aggregated TCP/IP throughput. Reference designs are licensed to manufacturers which modify and package them as unique products.

Atheros faces sharp competition from Airgo, Broadcom, and Marvell in the general market for providing Wi-Fi chips to manufacturers of consumer and enterprise equipment - the so-called OEM or original equipment manufacturer - and additionally from Intel in putting Wi-Fi into laptops. Intel would prefer its computer-making partners buy the whole Centrino Core 2 Duo shebang from them, Draft N chips included. These new designs are clearly aimed to ensure Atheros's manufacturing partners have the largest range of possibilities with the least amount of independent engineering.

In a briefing last week, Atheros's vice president of marketing Todd Antes said the firm sees the inflection point for Draft N products outpacing 802.11g products coming by 2008 as consumer products with Draft N become less expensive and more available, along with integration of Draft N adapters in notebooks and computers. "It's no longer just the early adopters," Antes said, who use Draft N.

Read the rest of "Atheros Expands Draft N Options with USB, Routers"

Posted by Glenn Fleishman at 5:00 AM | Permanent Link | Categories: 802.11n, Chips, Future, Hardware | No Comments | No TrackBacks

May 15, 2007

Wi-Fi Alliance Gives Draft N Certification Details

By Glenn Fleishman

DraftnThe Wi-Fi Alliance still targets late June for completion of its certification of Draft N devices: Equipment that conforms to Draft 2.0 from the 802.11 Task Group N as tested through a suite developed by the alliance will be able to display a new logo that incorporates the Draft N motif. Atheros, Broadcom, Cisco, Intel, Marvell, and Ralink provided reference designs that were part of the certification process. These products are now Draft N certified, but they're reference designs--they can't be purchased. Rather, the changes to these designs to reach interoperability will now filter out from the chipmakers to their OEM partners, the companies that make end user gear, like Apple, Buffalo, Linksys, and others. These OEM devices will then, in turn, receive certification as they update the firmware necessary to achieve that state and submit their equipment for testing.

Posted by Glenn Fleishman at 10:32 PM | Permanent Link | Categories: 802.11n, Standards | No Comments | No TrackBacks

May 9, 2007

First Draft N 2.0 Firmware Shipped by D-Link

By Glenn Fleishman

D-Link updates its Draft N product line to Draft 2.0 of the specification: This is the first announced firmware release of many expected for the existing draft 802.11n or Draft N product lines from companies like Apple, Buffalo, Linksys, and many others. Draft 2.0 is currently being used as the basis of an interim certification for 802.11n by the Wi-Fi Alliance that should see certified products by June.

Posted by Glenn Fleishman at 9:40 PM | Permanent Link | Categories: 802.11n | No Comments | No TrackBacks

April 16, 2007

Gefen: HDMI over UWB; Belkin: USB over 802.11n

By Glenn Fleishman

Gefen's first foray into ultrawideband didn't pan out: Gefen (along with Belkin) preannounced UWB-based cable-free USB hubs using Freescale chips way way back in Jan. 2006. Gefen abandoned the attempt entirely, but comes back to market with UWB-based HDMI (high-definition multimedia interface) extenders. HDMI couples audio and video in a single cable, and can wrap encryption (HDCP) on top of that if required by content owners. They're using Tzero chips to extend HDMI over UWB. It'll ship in June for $750 for a pair.

Belkin will ship a USB-over-802.11n hub in June for $130: This 802.11n-based USB extender requires host software for Windows. It has five ports. Mac software is due in August.

Belkin, by the way, has been promising its revised UWB Wireless USB four-port hub with host dongle setup since last year, when Popular Science gave it a best product award. The last update says the product would ship Jan. 12, which did not happen.

Posted by Glenn Fleishman at 12:01 PM | Permanent Link | Categories: 802.11n, UWB, Video | No Comments | No TrackBacks

April 11, 2007

NY Times Finds Draft N Underwhelming

By Glenn Fleishman

David Pogue reviews four 802.11n routers, and finds only Apple's meets most of the promise, Belkin second: Pogue was unable to achieve the highest speeds promised by these routers, except with the Apple AirPort Extreme. That may be because all these early routers are single band (2.4 GHz) except Apple's. They may also all be much more susceptible to interface or back-off from adjacent networks, although Pogue isolated a lot of variables. As other reviewers have found, range is much better than bandwidth, but Pogue wasn't able to get more than 49 Mbps from any device but Apple's. I have only thoroughly tested Apple's router, and achieved 70 to 80 Mbps in unoccupied 2.4 GHz channels.

Pogue had kind words for Belkin's Draft N gateway, due to its superb installation instructions and labeling and its  clear troubleshooting icons that are built into the front of the gateway. If there's a problem, an icon representing the part of the network that's faulty flashes an amber outline; network components that are okay are outlined in blue.

His conclusion? "If you’re in the market for new wireless gear and can’t wait a few more months for the “n” committee to finish the spec, buy the polished, upgradeable gear from Apple or Belkin." I'm not waiting for the spec to be finished, but rather anticipating a wave of firmware upgrades that should improve performance in the 2.4 GHz band based on the latest draft from the 802.11n committee. (Pogue says that Linksys didn't promise to him that the device he tested can be upgraded; the other three manufacturers did.)

While the draft was approved in March, it may be weeks yet before firmware appears for shipping devices that accounts for changes, especially in how 802.11n and previous 802.11 specs work together on the same network and in adjacent networks. The Wi-Fi Alliance will also announced certified devices sometime this quarter for Draft N, which would mean new firmware as a result of "plugfests" and other lab testing to achieve that seal of  interoperability.

Posted by Glenn Fleishman at 10:54 PM | Permanent Link | Categories: 802.11n | 2 Comments | No TrackBacks

February 16, 2007

How Draft N Makes Nice with Neighbors; 5 GHz Averts Tragedy of the Commons

By Glenn Fleishman

The soon-to-be-approved Draft 2.0 for 802.11n will protect 2.4 GHz legacy networks well, but is tuned for 5 GHz: A large part of the horsetrading involved in the IEEE Task Group N's work between Jan. 2006 and Jan. 2007 centered on making sure that Draft N didn't beat up its older relatives, 802.11a, b, and g. The constraints placed on 2.4 GHz will naturally steer new network deployments into 5 GHz, a better band for video streaming around the home as well.

I spoke with Atheros, Broadcom, and Metalink recently, along with the Wi-Fi Alliance, to look at how the current Draft N will protect legacy networks, and where N will take the consumer markets. (Last month, I wrote lengthily about some of the technical issues that make 5 GHz appealing, but may also constrain it.)

Read the rest of "How Draft N Makes Nice with Neighbors; 5 GHz Averts Tragedy of the Commons"

Posted by Glenn Fleishman at 4:50 PM | Permanent Link | Categories: 802.11n | 4 Comments | No TrackBacks

February 10, 2007

Apple's Codependent Problem

By Glenn Fleishman

Crazy Apple Rumors Site suggests that 802.11 is your problem: "Look, it’s one thing to be 802.11n. It’s another thing to be an 802.11n enabler."

Posted by Glenn Fleishman at 10:17 AM | Permanent Link | Categories: 802.11n, Humor | No Comments | No TrackBacks

January 30, 2007

Apple Ships 802.11n Base Station, Software Upgrade

By Glenn Fleishman

Ae-DiagramThe AirPort Extreme Base Station with 802.11n is now shipping: The software enabler required to update existing Macs that have 802.11n technology built in can also now be purchased from the Apple Store for $1.99. The enabler is included with the $179 Extreme gateway. All Core 2 Duo and Xeon-based Macs with Wi-Fi can be updated, except a single iMac model, but including Mac Pro desktops that had the AirPort Extreme option added. Apple isn't offering 802.11n options for any older Macs; third-party adapters will be required.

The enabler isn't locked to a particular Mac. David Moody, an Apple vice president, said, "You can install it on the all the Macs in your house." The license on the purchase page is even broader: "The software license for the 802.11n Enabler software allows you to install and use it on all computers under your ownership or control."

AirPort Extreme with N can work in either the 2.4 gigahertz (GHz) band, in which 802.11b (AirPort) and 802.11g (AirPort Extreme) operate, as well as in the 5 GHz band, which is less occupied and has greater available frequencies. While the new Extreme includes Wireless Distribution System (WDS) support for linking base stations wirelessly, and will work interoperably with the older AirPort Extreme and AirPort Express models. However, Moody said that the greater range of 802.11n should obviate the need for WDS connections in the home.

In 2.4 GHz, Apple won't allow 40 MHz "wide" channels that, in the absence of other Wi-Fi network signals, could double throughput. Moody explained that Apple has a huge interest in preserving the functionality of Bluetooth, which has shipped alongside Wi-Fi in most Macs in recent years. "We need to make sure Bluetooth and [802.11]g co-exist perfectly," he said. Allowing 40 MHz wide channels in 2.4 GHz would have severely constrained Bluetooth. Starting with version 1.2 of Bluetooth, that short-range networking standard actively avoids frequencies that are in use by Wi-Fi.

Jai Chulani, senior product manager at Apple, suggested that many users would be better served by preserving a legacy 2.4 GHz network for 802.11b/g devices with an existing base station, and plugging that older base station into an Ethernet port on the new AirPort Extreme, which would then operate to its best advantage in 5 GHz. The AirPort Extreme with N is configured to automatically choose the best channel in 5 GHz, but Chulani said that an advanced settings option would allow 5 GHz channel selection. This could be important, because four of the nine channels in 5 GHz that Apple is offering are restricted to a low-power mode.

Chulani also confirmed that the Apple TV could operate in either 2.4 GHz or 5 GHz bands, but that like the AirPort Extreme, the best mode of operation would be automatically selected, and could be manually overridden.

The AirPort Admin Utility has been updated for the new standard with an overhauled interface that, Chulani said, "has two faces." One features more automatic, sensible choices for users who don't need or want to customize configuration. The other includes even more technical detail than earlier releases. For instance, the separate, free AirPort Client Monitor, used to view connected devices and their signal strength, is now part of the AirPort utility. An update to the AirPort Management Utility for configuring multiple base stations at once will be released in the indefinite future. Mac OS X 10.4.8 or Windows XP is required to configure the new base station.

The pipeline for Apple's 802.11n is just revving up, and Macs sold at retail could need enabling. Purchasers of Macs that don't have the newer software installed will have to pay the $1.99 fee unless they also purchase the AirPort Extreme Base Station. It seems likely that the base station will drive the upgrade to 802.11n. The base station started shipping today, and orders placed at the time of announcement should be in purchasers' hands shortly, Moody said.

Posted by Glenn Fleishman at 12:42 PM | Permanent Link | Categories: 802.11n, Home | No Comments | No TrackBacks

January 24, 2007

5 GHz or Bust

By Glenn Fleishman

George Ou has some interesting points about 5 GHz, but there's more to the story: Ou hates the 2.4 GHz band with something greater than a passion--it's crowded, there aren't enough non-overlapping channels, and it's just so out of fashion. He's right about all that. The 5 GHz band has lots of possibilities, including 23 channels open for use. Before we get too excited, though, let me point out a few things that Ou didn't cover--primarily, the signal power output restriction for 5 GHz. 5 GHz 802.11 standards can't send signals as far as 2.4 GHz for a good hunk of the band. (23 channels are available for 802.11 specs; there are technically 24 possible in a different configuration.)

One of N's possible advantages of double-wide channels--instead of 22 MHz, they can use 40 MHz channels, which effectively doubles throughput. When you combine a newly efficient design for encoding, two or more radios, and double-wide channels, that's when you get the high symbol rate of 300 Mbps, with effective throughputs that could go well over 100 Mbps. The 100 Mbps throughput factors in--as I understand it--the expectation that N devices will have brief periods in which they can bond two channels.

Here's my executive summary so you don't have to read my entire analysis:

While 5 GHz is uncrowded and has more clear, non-overlapping channels that can be combined for the highest speeds in 802.11n, the rules governing 5 GHz for indoor use with omnidirectional antennas mean that only two double-wide channels in 5 GHz are available at anywhere near the maximum power (and thus potential range) of interior Wi-Fi. A number of 5 GHz channels offer power levels that are comparable to 2.4 GHz--and that assumes manufacturers will allow their 5 GHz radios to output enough juice to produce ranges similar to 2.4 GHz. But the lack of competing networks in 5 GHz could mean that 5 GHz N networks will almost certainly work much better in crowded RF environments--apartment buildings, for instance--than 2.4 GHz N networks which have very little chance to use double-wide channels. (Proviso: Some countries don't allow double-wide channels in 5 GHz.)

Ou says that "802.11b was supposed to have given way to its sibling standard 802.11a which operated in the 5 GHz range." That's not my recollection back at the time this was happening. 802.11b and a were seen as having somewhat different purposes: 802.11a had the potential for high-speed, short-range indoor connections, and long-range point-to-multipoint outdoor hookups. This was largely due to the higher cost of A, as Ou points out, but also due to the shorter range possible in indoor applications due to lower signal strength allowed. (Also, there were doubts about A's ability to be produced using CMOS chip processes, which Atheros put to rest, even as it moved into G for competitive reasons.)

He notes that while 802.11g boosted speed, "the problem was that in order to maintain backward compatibility, 802.11g also had to operate in the limited 2.4 GHz space and worse it had to switch to 802.11b if even one legacy 802.11b device joins the party." This isn't strictly correct as described, although it's widely stated this way. An 802.11b device forces a G network to drop down to B speeds only when the B device is transmitting or receiving data. There's a bit of extra network overhead, as well, if you choose for your G device to support B that does produce a single digit reduction in throughput even on G devices. The same will be true with N: older devices will occupy disproportionate amounts of time while transmitting or receiving, but if they aren't heavy network users, the N network should still work well.

I would argue that dual-band gateways didn't succeed in the consumer marketplace because of an absence of a compelling reason to use them. Throughput wasn't a big motivator. There were initially few adapters, none affordable, for 802.11a when 802.11g hit its stride. Remember Steve Jobs telling us 802.11a was dead? (Hey, their new device supports A, so I guess it got better.)

If you had mostly 802.11b/g devices and wanted to use A, you'd have to switch all your adapters over because no consumer devices supported simultaneous dual-band operation in 2.4 GHz and 5 GHz. Some enterprise hardware did (and still does) allow both bands either through two baseband chips or through two separate radios.

Ou complains that MIMO's leap into the market caused the lack of 5 GHz expansion. "Since it already required multiple radios for single band operation, adding an additional set of radio on the access point would have increased the already-high prices even higher." But there are few except very high end devices that would have duplicated radios; typically, as I just noted, it's one radio with two frequency ranges supported for either 2.4 GHz or 5 GHz operation.

Now here we get to the crux: Ou writes, "802.11n in my opinion should have NEVER permitted 2.4 GHz operation in the first place and should have only used the 5 GHz band." However, that idea has two flaws, one of which Ou admits and addresses. First, it breaks compatibility, which means that it's not a solution for people with B and G that want to gradually move to N. Ou suggests that a cheap single-radio could have been inserted into access points to handle B/G clients and the N system could have worked just in 5 GHz. Let's leave out all the radio engineering issues involved in that--like antenna coordination, cost of manufacture, firmware support, and so forth. The second flaw is more critical: 5 GHz has too many limitations in range.

The four spectrum hunks of legal 5 GHz channels each carry restrictions that don't dog 2.4 GHz, and that's why 5 GHz hasn't caught on. Where 802.11b/g/n devices can transmit as much as 1 watt of power at the antenna and use any channel indoors or outdoors, rules for 5 GHz prescribe in the U.S. and some other markets which channels may be used indoors only, and has much lower power levels for omnidirectional indoor use than 2.4 GHz allows.

There are now four bands in 5 GHz channelized for 802.11 in the US, although they're numbered somewhat strangely. In brief, there is total of 555 MHz across 23 channels in 802.11a/n. The lower four are indoor only; the higher 19 are indoor/outdoor. The lowest four (5.15 to 5.25 GHz) can have 50 mW of output power, the next four (5.25 GHz to 5.35 GHz), 250 mW; the next 11 (5.47 to 5.725 GHz), 250 mW; and the top four (5.725 to 5.825 GHz) up to 1 W. (There are further restrictions on 5.25 GHz to 5.725 GHz in terms of detecting and avoiding stepping on military radar transmissions, which share those bands. And the 802.11a spec specifies 40 mW/200 mW/800 mW instead of 50, 250, and 1,000, just to make it even more complicated.)

There are an enormous number of details about effective output, antenna gain, and so forth, but most of that affects the use of directional antennas and point-to-multipoint outdoor connections, not the use of interior omnidirectional antennas.

Because 5 GHz signals have shorter wavelengths than 2.4 GHz signals, at the same amount of power, they propagate shorter distances. They're also worse at penetrating solid objects. This means that even if you use the top four channels for 802.11a or single-wide channels for 802.11n in 5 GHz, you will only be able to send data less than half as far if that. There are only two double-wide channels possible in that top band.

In the 250 mW restricted range of 5 GHz, you could achieve the same range by using higher power in 5 GHz than in 2.4 GHz. But many of the devices that offer 2.4 GHz and 5 GHz radios don't compensate in 5 GHz by having higher-powered signal output. Thus a device that gives you 100 interior feet in any direction in 2.4 GHz could span less than 50 feet for this reason in 5 GHz. The lack of interference from competing networks could compensate for the shorter distance, however.

(Another issue: Some 802.11n device makers may not let you use double-wide channels in 2.4 GHz. Apple's new AirPort Extreme with 802.11n says in its advanced configuration manual--online already long before the product ships--that what it dubs the Use Wide Channels options is only available in 5 GHz. Conversely, Apple is promoting its AirPort Extreme with N in some European as only offering 20 MHz channels in 5 GHz because of regulatory limits. Thanks to Iljitsch van Beijnum for pointing to the manual and the European issue.)

Still, 5 GHz does offer some hope, and while Ou thinks the boat was missed, I see Apple's support in clients and adapters for 5 GHz in N, and Intel's support in its Centrino client for 5 GHz as a sign that that band will pick up steam. Note that Intel is certifying access points and routers with a Connect with Centrino label--and those devices will likely have to support 5 GHz, like this Intel-co-branded Buffalo router.

Let me reiterate one point here at the end: Manufacturers often limit their devices to 100 mW or even much less of output power for 2.4 GHz for reasons of cost. The problem in using 5 GHz will come entirely from whether those manufacturers decide to use the same power output limits for 2.4 GHz and 5 GHz even though they don't have to, or whether they'll actually take advantage of 5 GHz by boosting its power to put its range into parity.

Posted by Glenn Fleishman at 2:30 PM | Permanent Link | Categories: 802.11a, 802.11n, Future, Spectrum | 4 Comments | No TrackBacks

January 23, 2007

Intel Unveils N for Centrino, Partner Program

By Glenn Fleishman

KedronfrontOn the heels of Apple's commitment to 802.11n, Intel gets in the act: The timing is no coincidence. Apple and Intel have been coordinating messages, and even though Apple won't be using Intel's chips--Atheros appears to be the anointed party--Intel wanted to wait until after the IEEE task group vote last week and after CES, too. Apple jumped the gun by a few days.

Notebook partners include Acer, Asus, Gateway, and Toshiba committed at this point, with systems available at the end of January using Centrino Duo. The Santa Rosa laptop chipset platform is due in the second quarter of 2007, at which point they expect more participation.

Like Apple, Intel says five times the throughput, twice the range, but only in comparison with their previous products--no actual specs on megabits per second or feet/meters. They do note that N will provide an hour more battery life under comparable circumstances with the previous Centrino flavor. They will support 2.4 GHz and 5 GHz N channels.

The announcement includes the Connect with Centrino program, in which access point makers commit to rigorous testing with Intel to ensure interoperability. This is clever, because it will go beyond the Wi-Fi Alliance tests, which focus on wireless protocols, and include the whole ecosystem of DHCP addressing and other factors. Asus, Belkin, Buffalo, D-Link, and NetGear are all part of this first wave of branding.

Posted by Glenn Fleishman at 2:31 PM | Permanent Link | Categories: 802.11n, Adapters, Hardware, Standards | 1 Comment | No TrackBacks

January 22, 2007

802.11n Finishes in October 2008

By Glenn Fleishman

I'm not trying to be incendiary, but that's now the projected ratification date: Ephraim Schwartz files this detailed column for InfoWorld about the steps between now and then for moving 802.11n out of Task Group N and into the full body. Draft 1.10 was approved the other day; with minor changes that goes out as 2.0 to a larger voting pool. The odds are about zero at this point for any changes that will involve anything but firmware upgrades as there will  be an entire entrenched industry for Draft 2.0-based products.

The final ratification isn't expected until October 2008, but the spec will be nailed down by around January 2008, which was about the original plan as of a few months ago.

Recall that 802.11n was expected to be ratified in 2006 a couple of years ago. The roadblocks that prevented that have now been overcome.

Posted by Glenn Fleishman at 3:28 PM | Permanent Link | Categories: 802.11n | 1 Comment | No TrackBacks

January 19, 2007

802.11n Moves Forward with Draft 2.0 Vote

By Glenn Fleishman

Big news from the IEEE: Draft 2.0 of 802.11n moves forward: The vote was 100-0 with 5 abstentions, Matthew Gast notes from the London meeting. This is a significant milestone from a lot of different directions. It's one thing to achieve a 75-percent supermajority necessary to advance a draft into its final stages, which is just the tweaking and fixing that brings it to ratification with no significant alterations. It's another to get the bag of cats that are the stakeholders in the task group to vote unanimously.

Draft 2.0 now goes out for letter ballot, where IEEE members choose to move the process along further, but the vote to take the draft into that status indicates there should be little problem with the formal adoption as the final basis of 802.11n. (Technically, Draft 1.10 was approved, and if the letter ballot succeeds, the new draft will be numbered 2.0.)

This also means that it's extremely likely that my concern over the last nine months about early Draft N equipment not all being upgradable through firmware to a Draft 2.0 and final release standard will prove misplaced. With the industry providing no hardware upgrade guarantees--like, "We'll swap your gateway if we can't make it as fast as the standard says and fully interoperable"--I've been dubious about early adoption of Draft N, especially that equipment based on Draft 1.0. Further, most early gear has revealed remarkable inconsistency in performance and interoperability with even like devices in testing by magazines and online publications.

The vote today indicates that there's a very strong direction for 802.11n, and I expect within a matter of weeks that we'll see waves of firmware upgrades for existing products, real availability of Draft 2.0 chipsets--Airgo wasn't the only one working in anticipation of this accepted draft--and a timetable for the Wi-Fi Alliance to certify Draft 2.0-compliant devices.

After four years, this is a big step forward.

Update: Atheros released a statement from their CTO that Atheros's Xspan chips can be made compliant with today's approved draft via a software update.

Broadcom's Bill Bunch also said in an interview, "All of our products that we've ever shipped since Day One will be upgradable to the final draft 2.0." It's all about firmware upgrades now.

Posted by Glenn Fleishman at 7:49 AM | Permanent Link | Categories: 802.11n | No Comments | No TrackBacks

January 18, 2007

Intel to Unveil Kedron Chipset with 802.11n

By Glenn Fleishman

TG Daily says Intel will announce Draft N chipsets next Tuesday: The site writes that the Kedron wireless chipset may already be in finished devices, and Intel's announcement could mean they have equipment from partners to show with the Draft N standard enabled. Kedron will work in conjunction with Santa Rosa, the next-generation laptop chipset, which is due in second quarter 2006.

Posted by Glenn Fleishman at 5:03 PM | Permanent Link | Categories: 802.11n | No Comments | No TrackBacks

January 18, 2007

Apple Confirms $1.99 Price for 802.11n Updater

By Glenn Fleishman

Just off the phone with Apple, which says Mac owners with 802.11n-capable hardware will be charged a $1.99 fee: A spokesperson with Apple provided me with a response that explains that the updater will be available for purchase from their online store at a "nominal fee" in order "to comply with Generally Accepted Accounting Principles for revenue recognition, which generally require that we charge for significant feature enhancements, such as 802.11n, when added to previously purchased products."

The company will eventually fully enable 802.11n on all Macs with appropriate hardware that they ship. The spokesperson couldn't yet provide a timetable for when that switchover would happen. If you purchase a Mac with Draft N chips between now and then, it's possible you would need to pay the $1.99, but, frankly, you'll just find someone with the enabler, won't you?

The enabler will be included on the new AirPort Extreme Base Station's CD.

Posted by Glenn Fleishman at 12:30 PM | Permanent Link | Categories: 802.11n | 2 Comments | No TrackBacks

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