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Stephen Lawson at IDG News Service rounds up the status of Wi-Fi Direct: I've thought Wi-Fi Direct is quite promising since its introduction, and Lawson explains where all the support for the standard is to be found, along with why it's hardly available. Wi-Fi Direct is a simple way to create a kind of ad hoc, WPA2-secured network between two devices. It will likely be used for file transfer between mobiles and for printing when you don't have access to the network to which the printer is attached.
Lawson doesn't mention it, but I keep coming back to operating system support. No mobile OS offers Wi-Fi Direct yet, which keeps the most promising market from using the service. Mac OS X and Windows 7 also don't include support. To use Wi-Fi Direct, you need a device that advertises itself in the right fashion and can create the secure connection, and a client that can connect to it.
Wi-Fi Direct hasn't failed, to be sure, but we're still waiting for real signs of life.
The closest example I use routinely now is AirPrint, built into the iOS 4.2 release for iPhone, iPod touch, and iPad. Apple's solution is extremely limited in this release, allowing straightforward printing from any of its mobile devices to certain models of HP printer. The original AirPrint announcement said it would work with any Bonjour-capable device (that's the standard Apple developed and uses for service announcements on a network). One suspects we'll find that in the upcoming 4.3 release.
In the meantime, I use Printopia, a $10 utility that makes any Bonjour printer appears as if it's a qualified HP device. It also lets you "print" to PDF to the computer on which it's running, and print a PDF directly to Dropbox.
With AirPrint, I select the action button in any program that supports the standard set of forwarding commands, like send via email, and choose the Print option. I'm given the choice to select among printers (real and virtual), and then the item is sent without fuss.
That's what Wi-Fi Direct should work like, with little additional fuss, and I'll be happy when that notion is realized in hardware and software.
Five chipmakers have certified Wi-Fi Direct reference designs: Wi-Fi Direct is a terrific addition to wireless networking where a device that offers a service can broadcast that service's availability, like printing or file exchange or what have you. It's a form of peer-to-peer networking that doesn't require an access point to intermediate, and is ideal for mobile devices, and devices that lack much of an interface. The first five reference designs have been certified a few months later than the original rough target announced last year. (See "Wi-Fi Alliance Peers into the Future with Ad Hoc Replacement," 13 October 2009.)
Wi-Fi Direct has a few things in common with newer Bluetooth devices that pair with less effort than in the original Bluetooth schema, and in that Bluetooth and Wi-Fi Direct both advertise available services. But the notion is that you get the speed (up to 802.11n) and security (WPA2 mandatory) of Wi-Fi with enormously simpler setup than connecting to a new Wi-Fi network for a moment and then setting up a connection with a specific device. And in cases in which you don't have an access point, such as trying to exchange a file between two mobile devices, it's extremely irritating. (On an iOS device, both parties could have a package like GoodReader that has built in WebDAV client and server software with Bonjour discovery, but you still need an access point to which both devices are connected, and security is an overlay.)
This announcement went around the world like a shot, but was typically covered incorrectly or incompletely in four ways. First, this is nothing new. The spec was announced a year ago; this is the culmination in silicon of that effort. It's great to see this implemented, because now we can move forward to have devices that support it.
Second, it's not yet available. The five certified devices are reference designs that other companies (OEMs or original equipment manufacturers), like Linksys, D-Link, Dell, Acer, and the like will build into products or relabel to sell under their own names. That means there's still some time to the market.
Third, this is host-side stuff—things to make a computer act as a Wi-Fi Direct enabler. It's not the technology needed for embedded client-side support in, say, an HP multi-function printer.
Fourth, there is no announced operating system support yet, even though Microsoft and Apple sit no the Wi-Fi Alliance board. That is not unusual for newly released hardware implementations of standards from the Wi-Fi Alliance or other groups. Apple and Microsoft both have near-term releases of operating systems upgrades on the timeline (Mac OS X 10.7 and Windows 8). It's most likely Wi-Fi Direct would appear in a new system, and might not be available in an older device.
Finally, and this wasn't addressed in any of the coverage I saw, you're going to need to see widespread adoption in mobile operating system platforms to make Wi-Fi Direct truly useful, and integration at a fundamental level of the OS. That means Android, BlackBerry, iOS, Palm WebOS, and Symbian (whichever version), as well as featurephone platforms from Nokia and others.
The reason is that mobile OS's, even the supposedly open Android platform, need to put Wi-Fi Direct hooks down into the driver level so that third-party developers can hook into a system-wide printing library that works with Wi-Fi Direct, or file-transfer support within apps.
Wi-Fi Direct is terrific, and I will be glad when it's widely available, But my prediction is that it won't have widespread impact until 2012. On the Wi-Fi timeline, that's perfectly fine. Each 802.11 standard as certified by the Wi-Fi Alliance has taken 2 to 4 years to percolate into the market. WPA2, rolled in 2004, is just now becoming the de facto security method, for instance. Wi-Fi Direct's greatest impact is on the future, not the present.
The ITU sets the minimum for 4G designation: The International Telecommunication Union Radiocommunication Sector (ITU-R) has reaffirmed previous less settled criteria for what's a fourth-generation (4G) network. Current WiMax and LTE is nowhere near the cutoff point of 100 Mbps downstream for mobile and 1 Gbps downstream for fixed.
This isn't new, although this particular decision is new. I've been wondering by what logic Clearwire, AT&T, and Verizon were labeling current WiMax and first-generation LTE deployments as 4G, when they're incremental, welcome improvements over 3G. Some of it is architecture. As Stephen Lawson of IDG News Service notes, these networks were designed from day 1 for data, and are all Internet protocol (IP) from end to end. That's a huge improvement over 3G and it's a marked change.
The ITU-R doesn't do enforcement, and 4G isn't a trademark. Verizon Wireless and Clearwire told IDG's Lawson that the ITU-R move has no effect on their branding or deployment plans (nor should it on the latter).
My question for 4G deployment, of course, is that with it on track for 2014–2015 rollout, how realistic is it to come up with the channel widths necessary? It looks like the maximum speeds being discussed require extremely wide channels, like 100 MHz. That's not impossible, but no U.S. carrier has 100 MHz in a chunk that it materialize. The FCC white-spaces rulemaking frees up a bunch of 6 MHz pieces, and that's the last major realignment after DTV 700 MHz spectrum that I'm aware of.
The definition of 4G may now be set, but the ability to roll out 4G at anything like the minimum speeds promised seems highly problematic even in five years.
The Wi-Fi Alliance has a timetable for eliminating outdated WEP and TKIP security from certified Wi-Fi devices: A couple of news sites ran unsourced stories yesterday and today about a roadmap from the Wi-Fi Alliance for eliminating older encryption methods from the certification process for new hardware.
I picked up the phone (yes, crazy, I know!), and confirmed it: TKIP and WEP won't be allowed in new devices with the Wi-Fi stamp in a staged elimination over three years starting in 2011.
Anyone reading this site should be well aware that WEP (Wired Equivalent Privacy), the original local-link encryption standard in 802.11b, has been broken since 2001, and horribly so since 2003.
TKIP (Temporal Key Integrity Protocol) was a backwards compatible replacement introduced in 2003, and intended to work with older silicon that didn't have either the circuits or computational muster to handle WEP's real replacement, AES-CCMP (you don't want to know what that stands for, honestly). AES (also from 2003) is often called WPA2 encryption, although it's more particularly an encryption type that's part of WPA2.
While TKIP hasn't been broken, it has known vulnerabilities, such as a susceptibility to dictionary-based attacks for short keys (eight characters), and some very clever ways to insert packets through manipulating a flaw in the packet integrity protocol. (See my 2008 Ars Technica article, "Battered, but not broken: understanding the WPA crack," and my article on this site, "Another, Better TKIP Attack That's Still Limited" from Feb. 2010. It's likely more will be found.)
The 802.11n standard only allows the use of AES keys, which sometimes provokes confusing statements about its capabilities. Apple updated a support note on 3 June 2010 which stated that 802.11n with WEP or TKIP could only operate at 54 Mbps, when it's perhaps more accurate to state that 802.11n drops down to 802.11g to handle these older security types.
Kelly Davis-Felner, the Wi-Fi Alliance's marketing director, said, "We had a process within our membership to say we have a few aging security mechanisms, one of which is known to be obsolete - and that would be WEP, of course - and we wanted to define what the roadmap would look like to get the whole industry to end of life" the technology.
The Wi-Fi Alliance is a membership trade group that sets certification standards for products that bear the Wi-Fi seal. As such, its efforts are driven by what the members want, and the group allows a typically consistent approach across the entire industry.
The alliance's product manager for putting WEP and TKIP out of their misery, Sarah Morris, said that TKIP and WEP will be phased out in stages starting 1 January 2011 until 1 January 2014. Changes affect only new devices seeking certification. Companies can also release 802.11 equipment without the Wi-Fi imprimatur, although that's extremely rare, and essentially unheard of among any major equipment maker.
At the start of 2011, access points will no longer be certified with TKIP as an option by itself, commonly revealed as WPA-PSK, WPA-TKIP, or WPA Personal. Mixed modes, in which an AP can accept either TKIP or AES keys, will still be allowed.
But also starting in 2011, manufacturers can opt to ship Wi-Fi hardware preset to use WPA2 out of the box. Currently, Wi-Fi-certified access points have to be set to open, and a purchaser configures it to use security. This is an interesting change, and part of what Davis-Felner said will be greater efforts in the coming year to promote security.
In 2012, new Wi-Fi adapters (so-called stations in 802.11 parlance) won't be allowed to support TKIP.
In 2013, WEP is finally disallowed for APs. While that seems incredibly late, its inclusion is there only for certain categories of legacy devices for which no other option is available. WEP is used by point of sale systems and older hardware that can't be upgraded. It's perhaps too kind to leave it as an option for that long, but it's also a membership decision, so clearly justified by a remaining installed base.
In 2014, the mixed TKIP/AES mode for access points can no longer be included in certified devices, and WEP cannot be available to new client devices.
The move to an all-AES world is long in coming. "You've heard us say for a long, long time that WPA2 is the recommended configuration for any Wi-Fi network or enterprise," said Davis-Felner. "This is a strong expression of that position."
Good news for those of us that like harmony in standards-land: The Wi-Fi Alliance and WiGig Alliances have agreed to cooperate on technology for networking in the 60 GHz band. This is terrific, and not unexpected. The two groups share many members, and a fairly common purpose, distinct from the WirelessHD group which is using 60 GHz for streaming high-def video. (The announcement was set for 10 May 2010 at midnight, but some outlets broke the embargo.)
The 60 GHz band, also known as a millimeter band for its wavelength, can allow up to 7 Gbps in short-range data transmission in the US and many other countries, with multiple channel configurations allowed to operate in the same space. The short wavelength means short propagation, mostly in room.
The IEEE has a 60 GHz task group (802.11ad) that's paired with its sub-6 GHz 1 Gbps group (802.11ac) as part of two separate moves forward to faster WLANs. The Wi-Fi Alliance would likely certify specific characteristics of 802.11ad for 60 GHz.
But it's been seen as quite likely that a single Wi-Fi adapter in the future would handle 2.4 GHz for compatibility and range, 5 GHz for performance and reduced interference (also where 802.11ac is focused), and 60 GHz for short-range super-fast data transfers. Having the WiGig group's specification now aligned with the future of 802.11 and Wi-Fi will make it easier for manufacturers, computer systems' makers, and home and business users.
Competing standards in computer hardware have been clearly shown to stall market development. Competing offerings differentiated by design, features, and integration are were the money is at.
The areas Wi-Fi Direct can best Bluetooth are on distance and speed: I've written a few articles already about Wi-Fi Direct, the new peer-to-peer mode that the Wi-Fi Alliance is finalizing and which will appear in updated and new hardware in mid-2010. This includes my analysis of why Bluetooth and Wi-Fi Direct serve related but not entirely overlapping purposes. But in that discussion, I only mentioned speed and distance in passing.
Bluetooth devices come in one of three varieties by signal output: Class 1, 2, or 3. Class 3 devices (1 meter, 1mW) were originally the most common, intended for low-power earpiece-to-phone communication. Class 2 (10 meters, 2.5 mW) became more common, and I believe now predominates. This allows communication within a room and sometimes beyond. Class 1 (100 meters, 100 mW) is rarely found in peripherals, although it's used in computers. The Callpod Dragon V2 headset ($99) is a rare peripheral exception, but the size and price have something to do with its ability to push out that much signal.
Wi-Fi, in contrast, is designed for whole home/whole office coverage, with 802.11n finally achieving that for many venues. Wi-Fi equipment makers used to, and some still do, put out nominal distance numbers, like 100 meters diameter or what have you, but I always thought these numbers were nonsense. Originally, these distances were based on minimal testing in simulations of the real world. Some companies and trade groups have houses that are designed to be testbeds, even.
In practice, 802.11g Wi-Fi was a one to two wall and one, maybe two floor solution. A lot of factors about building materials affected that. 802.11n penetrates far better, and can produce a far clearer signal (and thus higher speeds) through many more obstructions.
For Wi-Fi Direct, where you want to be able to peer easily to devices around you without fuss, the distance and penetration issues may be one important component of why people may turn to use that mode rather than Bluetooth. It's possible that some operating system makers or third-party software developers will make it simple for Wi-Fi Direct to become an ad hoc Internet access mode, bypassing the need for guest networks in access points, for instance.
Speed will also be a component depending on the uses to which Wi-Fi Direct is put, and how OS makers and device makers incorporate the mode. If Apple lets me use Wi-Fi Direct on an iPhone to transfer data from an Apple TV or a Mac or Windows system with iTunes installed (say, as an extension of the firm's new Home Sharing feature in iTunes), then I will surely want the 50 to 150 Mbps available with Wi-Fi Direct instead of the 2 Mbps of throughput from Bluetooth 2.1+EDR.
This draws me back to the application and profile issue I discussed in the previous article on Bluetooth competition. The usage Wi-Fi Direct beyond simple file transfer and Internet access and printing will depend heavily on having layers of functionality (tasks and purposes) put on top of connectivity.
Wi-Fi Direct is both parallel to and complementary of Bluetooth. Discuss: Today's announcement of Wi-Fi Direct, a peer-to-peer Wi-Fi transfer method, might seem to be firing across Bluetooth's bow. But it isn't quite. Intel's My WiFi is a much more direct threat, and even then may not materialize in quite the way that's being predicted. (Read my coverage, "Wi-Fi Alliance Peers into the Future with Ad Hoc Replacement.")
To review, Bluetooth is a PAN (personal area networking) technology in which devices under the control of the same person or computer communicate over short ranges and relatively low speeds. Bluetooth can create peer-to-peer connections or piconet networks, which comprise a host and up to seven clients. In a very standard configuration, a cell phone might use Bluetooth to communicate with a laptop, sharing its 3G mobile broadband connection, while at the same time a Bluetooth earpiece is paired with the phone to handle audio.
Bluetooth requires a pairing process, in which devices authenticate to each other and agree through a handshake (with optional encryption) to talk to one another. The SIG, device makers, and desktop and mobile OS developers have done a great job of simplifying this process down to typically entering a PIN--one of several options with the current security system, Secure Simple Pairing--instead of having 20 to 25 steps as it used to be.
Bluetooth's current release (2.1+HDR [high data rate]) encompasses a wireless spec for 3 Mbps data transfer (raw) using the 2.4 GHz band. The spec also includes application-layer elements, which are called profiles, and which define a large array of end-to-end tasks, like printing, file transfer, or acting as a modem. This allows any manufacturer to make a Bluetooth keyboard that talks the HID (human interface device) profile, and which is tested and certified as such, to talk to any other Bluetooth device with the HID profile.
The Bluetooth SIG, which maintains and develops the spec, isn't tied to its physical medium. It's tried to partner with other specs in process to extend itself, notably tying its cart at one point to both major ultrawideband (UWB) encodings, and then picking WiMedia, which was the "winner" in UWB. WiMedia disbanded, but handed off the Bluetooth component to the SIG; there may still be life in it. (Originally, Intel et al. wanted to stick one UWB radio in computers and devices, but have many different protocols run over that radio, such as Bluetooth, TCP/IP, Wireless USB, and video. UWB is currently shipping only as an instantiation of Wireless USB.)
While UWB fiddled and burned, however, the SIG worked on Bluetooth 3.0+HS (High Speed), which incorporates a high-speed transfer mode that allows a Bluetooth device to coordinate with a peer switching to use 802.11 for a bulk transfer, useful for large files or high-speed video streaming. The session is still within the structure of a Bluetooth PAN, and the use of 802.11 is entirely under the control of the Bluetooth session. The devices don't suddenly become ad hoc nodes or soft access points. Note the use of 802.11: this is a particular use of that protocol outside of any current Wi-Fi spec.
Wi-Fi Direct is an outgrowth of the interest by Intel and others in reducing the number of radio technologies and the level of complexity in devices, which can correspondingly reduce battery usage, while also developing a spec that's to their liking. Intel has a board seat on the Wi-Fi Alliance and the Bluetooth SIG, but still enjoys charting its own course.
Wi-Fi Direct is a peer-to-peer technology, at least the way it's being described initially. Wi-Fi devices that have services to offer (like printing, file sharing, etc.) can advertise those in a way that other equipped devices can access directly. This new method offers the speed and security of an infrastructure Wi-Fi network with an access point at the center without the overhead of joining such a network or making such networks public to allow access to specific resources. That is, someone can print to your printer without you giving them a key to your network. Wi-Fi Direct is built on top of 802.11n, so it can work in both 2.4 and 5 GHz, too.
The simplicity of Wi-Fi Direct is supposed to aid in devices without keyboards or easy data entry methods, much as Wi-Fi Protected Setup (WPS) was supposed to offer a one-click secure connection. With a peer-to-peer approach, a camcorder could hook up with a laptop to transfer data directly without you needing to enter a WPA2 Personal passphrase or even connect at all to an existing Wi-Fi network.
Beyond speed and security, Wi-Fi Direct will allow an adapter to be scanning and accessing peers while also maintaining a full infrastructure connection to a network. It's this feature that allows devices to ostensibly cut the Bluetooth "cord," although I'm still dubious about that as a general element, as I'll explain.
The My WiFi technology that Intel developed (apparently at least in part with Ozmo Devices) emphasizes more of the PAN aspect, talking about having eight devices associated with a laptop, for instance.
So, the question at the outset was whether Wi-Fi Direct is a competitor to Bluetooth?
Bluetooth and Wi-Fi Direct definitely compete head to head on trying to make the simplest network connection between two devices for a variety of straightforward purposes.
However, Wi-Fi Direct won't be backward compatible to the hundreds of millions of devices on the market that already have Bluetooth 1.x or 2.x. Bluetooth's later flavors (2.x and 3.x) are backwards compatible with those older devices.
And while Wi-Fi with a PAN mode could reduce circuit counts, most Wi-Fi chips that are being sold in the mobile market, and I believe in the desktop/laptop market, are integrated Bluetooth/Wi-Fi modules that often throw in other radios and circuitry as well.
Wi-Fi may eventually be appropriate to build into keyboards, mice, wireless headsets, earpieces, and other low-battery peripherals, but that's not really the case today. Bluetooth dominates there in hundreds of millions of installed devices.
Bluetooth's profiles also seem like an advantage to me. Kelly Davis-Felner, the Wi-Fi Alliance's marketing director, said that Wi-Fi Direct would not have application or task overlays, but would be focused on the networking and communication level, as with other Wi-Fi certifications.
Which means that if I connect my mobile phone with my computer to transfer music over, I still need an application on both sides that handles the file transfer. With Bluetooth, the profiles still need an interface on top, but a universally supported file-transfer method already exists. I can use a Bluetooth program under Windows and on the Mac and within various mobile phones to transfer files today.
If I want a method that synchronizes stored files and handles it automatically, then OS makers or third-party developers still do have to build an application on top of that. But with Bluetooth, they can rely on leveraging a well-supported mechanism. It's asymmetric, in that a desktop OS program for syncing MP3 files or photos doesn't require a corresponding program to be installed on a mobile phone that allows access to its storage via the Bluetooth profile.
Now, of course, I'm being a little disingenuous about profiles, because Wi-Fi Direct will create an IP-based network between the two parties, allowing existing service discovery methods to work just as they do over a wireless LAN today--including Apple's Bonjour and whatever the current name of Microsoft's technology. But none of these methods are supported across gadgets (like cameras). mobile operating systems, and desktop/laptop operating system platforms. That's going to be the challenge for Wi-Fi Direct.
In the end, I certainly see Wi-Fi Direct as provoking additional industry efforts to figure out precisely what's useful about PANs and sell those capabilities to consumers as solutions for frustration or a way to accomplish tasks they're unaware they need to accomplish.
The best thing about Wi-Fi Direct is that it enables a secure, high-speed ad hoc mode that will actually work among different devices, something that's long been needed.
One of the most interesting aspects of Wi-Fi Direct is that it could be used with Bluetooth, since many manufacturers participate actively in the Bluetooth SIG and Wi-Fi Alliance. Beyond Bluetooth 3.0+HS, there could be a convergence path for hand-in-hand networking, playing to each standard's strengths.
Strong peer-to-peer mode added to Wi-Fi portfolio: The Wi-Fi Alliance has announced Wi-Fi Direct, a peer-to-peer wireless networking method that takes the group into a new realm of creating specifications de novo, instead of following IEEE groups. The spec will appear in hardware by mid-2010.
Wi-Fi Direct will allow any device to advertise itself as a combination of software access point and peer. Newer hardware--which will include some existing equipment with firmware upgrades--will be able to maintain a wireless LAN connection to a so-called infrastructure network (via an access point), while also creating a peer-to-peer link to a device like a printer, mouse or keyboard, computer, or handheld. This could be used for file transfers, printing, input, and synchronization, among other purposes.
The spec is backwards compatible with 802.11a and 802.11g, which will see the peering device as a software access point, if I understand that detail correctly.
Wi-Fi Direct will include mechanisms for advertising service availability without connecting, something like the Apple Bonjour method known generically as Zeroconf that uses DNS records to broadcast specific services over a LAN.
The new method is a wholesale replacement of the weak ad hoc networking mode that's part of 802.11, but never built out into a standardized, certified part of Wi-Fi. Ad hoc networks allow devices to exchange data with each other without an access point, but implementations almost universally offer poor security and degraded throughput.
Distinct from ad hoc networks are software access points, which mimic all the functionality of an infrastructure network, and must be operated in a continuous fashion on a computer.
The Wi-Fi Direct mode will not suffer from weaknesses of either type of quasi peer-to-peer methods, and will be rigidly tested for interoperability among devices. Kelly Davis-Felner, the alliance's marketing director, said in an interview that Wi-Fi Direct can preserve the full bandwidth of 802.11n, as well as use WPA2 encryption and WPS (Wi-Fi Protection Setup) secure key handling.
Davis-Felner also said that while the spec has a lot of consumer electronics and home user advantages, enterprise management was baked in as well. The spec requires "Wi-Fi Direct networks to be seen by enterprise APs, and, potentially to be shut down by them" to prevent rogue networks that violate policy, she said. The spec also includes optional mechanisms that allow enterprise access points to suggest channel assignments and power management choices. The spec was designed to be an "enterprise-acceptable solution," Davis-Felner said.
The alliance has pulled together support from many non-standardized PAN/WLAN hybrid modes that have been under development, most notably the Intel My WiFi personal area networking (PAN) extension of 802.11. Intel said via email that Wi-Fi Direct would be incorporated into Intel My WiFi, which has additional capabilities. (My WiFi supports up to eight devices in a PAN configuration, much like Bluetooth.)
Chipmaker Atheros also offers its Direct Connect mode (in addition to a soft access point feature), which it said via email can converge into Wi-Fi Direct. (Oddly, Atheros has no plain product briefing page on this mode.) Marvell has a similar hotspot-on-a-chip offering, and plans Wi-Fi Direct support.
"This has been by far one of the most dynamic and heavily participated in groups that we've had in the Alliance," Davis-Felner said.
Wi-Fi Direct is a bit of a departure for the Wi-Fi Alliance, which typically develops a set of parameters from IEEE standards that a Wi-Fi-compliant device should support, and then builds interoperability testing and certification around those parameters.
With the initial release of Wi-Fi Protected Access (WPA), the Wi-Fi Alliance reacted to the interminable delays at the 802.11i security task group by splitting the backwards-compatible components from all the future-looking elements. WPA was based on an interim 802.11i draft, but ultimately was updated to WPA2 to incorporate the final work of the group.
Here, the alliance isn't following the IEEE, which has no PAN/WLAN convergence group, but maintains separate WLAN (802.11) and PAN (802.15) efforts. The 802.15 group has famously suffered from mid-stream shifts in technology approaches and the disbanding of 802.15.3b (high-speed PAN using UWB).
Wi-Fi Direct could be seen as a challenge to Bluetooth, given that Bluetooth is designed entirely as a PAN, and has a specification that will soon see light that allows Bluetooth to trigger an 802.11-compatible bulk-transfer mode for large files at faster rates. Bluetooth had paired itself with UWB as its next-generation wireless medium, but generic UWB radios never reached market, although there's still some potential.
The Wi-Fi Alliance announced this morning that it has started certifying fully compliant 802.11n devices, along with new optional elements: The group, which tests 802.11 gear for interoperability, is graduating from the Draft N trademark and testing to plain old N, with updates to logos and processes.
As noted in my earlier article, "The Fine Points of Optional Wi-Fi 802.11n Certification," 2009-08-07, the Wi-Fi Alliance added four additional optional certifications for a third spatial stream, better 2.4 GHz coexistence, space-time block coding, and packet aggregation. A few other tweaks are also added, described in that article.
The biggest change we'll see from the completion of the 802.11n standard and this certification update is three-stream N, which will allow raw data rates of 450 Mbps, along with the potential to simultaneously address three mobile devices at one time that are using single-stream 802.11n. This is likely to have much less impact in the home than in the enterprise, of course. Four-stream, 600 Mpbs devices are still in the future.
The alliance only releases new certification programs after testing with reference gear from major chipmakers, this time involving Atheros, Broadcom, Intel, Marvell, and Ralink. The companies involved all shot out press releases today describing their involvement, and how cool all this new gear will be.
It's likely that as the result of certifying new gear, older devices will see minor firmware updates as tweaks are made. The space-time block coding changes conceivably can be rolled into older devices, as well as some of the packet-aggregation updates. Both improve throughput depending on network conditions.
If I had larger type, I'd use it: The IEEE Standards Board has formally ratified the 802.11n standard (802.11n-2009, to be extraordinarily specific). It took seven years and involved 400 members from 20 countries. Somebody deserves a vacation.
Successor standards committee's are already underway, of course, but it's likely years before we see products based on 802.11ac (6 GHz and below) and 802.11ad (60 GHz), both of which aim for speeds of 1 Gbps and faster.
Somebody go put masking tape over the word "draft" on all those Wi-Fi boxes.
As far as any firmware revisions based on tweaky late changes to the spec, it's unlikely. From what I can tell from colleagues and the Wi-Fi Alliance, it's much more likely that newer devices will add features than current devices will see (or require) firmware changes.
On 7-August-2009, I wrote up the four major additional features coming to the Wi-Fi certification process, some of which were dependent on the late-stage draft changes in 802.11n. See "The Fine Points of Optional Wi-Fi 802.11n Certification."
The four new certification elements mostly, but not entirely, related to improving raw speed or net throughput.
The Wi-Fi Alliance explains four optional 802.11n elements for future certification: The Wi-Fi trade group has over the last 10 years kept together the notion that every device with Wi-Fi on the label should work at the greatest point of agreement with one another. This has continued in spite of new elements and enhancements to the 802.11 family of standards, including 802.11n.
The recent news that the IEEE had approved 802.11n within the 802.11 Working Group, and ratification was likely a few months away, led the Wi-Fi Alliance to explain its roadmap for adding more steps to the certification process. When the Wi-Fi group certifies a device, it runs it through tests that are supposed to ensure that the equipment responds in a standard manner. (The group also does plugfests in which equipment makers bring lots of gear together outside of lab conditions.)
When the word hit, the alliance identified four optional areas of certification that it would add. I knew about some of these areas, but I spoke with the group today to clarify what this meant for both equipment makers and end users. The Wi-Fi Alliance said it would offer tests for coexistence in 2.4 GHz, space-time block coding, transmit MPDU, and three spatial streams. Scratching your head? After 8 years of covering Wi-Fi, I admit I was in that position over a couple of those.
Let's go through them with the help of Greg Ennis, the alliance's Technical Director, who--along with Kelly Davis-Felner, the group's marketing director--was kind enough to lead me through it.
Coexistence. I first wrote about 802.11n coexistence mechanisms in depth back in Feb. 2007, when I interviewed Atheros's CTO Bill McFarland when the Draft 2.0 approval was imminent (see "How Draft N Makes Nice with Neighbors; 5 GHz Averts Tragedy of the Commons," 16-Feb-2007).
Coexistence has to do with the use of double-wide channels--40 MHz instead of the roughly 20 MHz regular channels--in both 2.4 and 5 GHz bands. The 5 GHz band isn't a problem, because 20 MHz channels don't overlap; Wi-Fi selectable channels in 5 GHz are staggered by intervals of 4 band channels (5 MHz each), such as 36, 40, 44, and 48. In 2.4 GHz, channels are staggered only by a single 5 MHz band channel, meaning that the use of 40 MHz will nearly always conflict with other existing networks.
Ennis said that 2.4 GHz coexistence terms weren't fully settled until recently, even though manufacturers have built in some methods of using 40 MHz in 2.4 GHz. The Wi-Fi Alliance discouarged the use; Apple, for one, doesn't allow its gear to use wide channels in 2.4 GHz.
In the new testing regime, "not everybody is required to support 40 MHz operation--but if they do support 40 MHz operation, they must go through the testing that we've defined," Ennis said.
The mechanisms that require an access point backing off to 20 MHz channels are so broad and severe that it's unlikely you could use a wide channel in any environment in which other Wi-Fi networks operate. Still, Ennis says, it may be of use in enteprise situations, or with future gear that's all 802.11n with these modes enabled that can be more respectful of each other automatically.
Space-time block coding. This term makes my head hurt every time I read it. I go off to the Web and read up on the principle, and it's above my paygrade. All wireless communication has to allot slots in some fashion--through contention or scheduling--for bits to go through. That's the basis of all wireless standards.
What STBC does is extend that beyond time into the domain of space. An access point can, through some complicated encoding, send different information simultaneously using multiple spatial streams so that receivers (stations in Wi-Fi parlance) that have single-spatial stream receivers can separately but at the same time decode their unique package.
The utility of this complicated feature is that we're likely to start seeing lots of single-stream N devices, as I've written about in the past year. (See, for instance, "Does the iPhone Need 802.11n?", 26-March-2009.)
Chipmakers are most likely now delivering quantities of these lower-powered, cheaper 802.11n chips that can't offer two streams--and thus double the bandwidth--as laptop and desktop 802.11n modules can. With STBC, an access point can utilize the full available 802.11n bandwidth by splitting it spatially between two devices instead of halving bandwidth by speaking to a single-stream device solely.
Ennis noted that STBC also improves the signal-to-noise ratio, which makes faster rates and farther distances possible. "I think this is going to be a popular optional feature," he said.
Aggregation MPDUs (MAC Protocol Data Units). While sounding obscure, this is yet another way by which 802.11n can eke out improved speeds. For long sequences of data, aggregation MPDUs lets a Wi-Fi system create a long frame, reducing all the overhead required to send a packet. (Every packet has origin and destination information, a preamble, and other data that adds overhead.)
For video, for instance, Ennis says that this kind of aggregation can improve throughput, although probably not by double-digit percentages. "It's not as dramatic an improvement as say using more spatial streams, or using 40 MHz channels," he said.
Currently, the Wi-Fi Alliance tests aggregation only if a manufacturer's access point sends these aggregated frames; it checks that a station can properly receive such frames, which can be interpreted under earlier 802.11n drafts. The new optional certification tests for aggregated frames sent by both stations and access points. (If included, it must be tested.)
Three spatial streams. This last one is quite simple. The Wi-Fi Alliance can now test for devices that send three streams of data across space up from two streams of data. Ultimately, we should see devices that can handle four, with a maximum raw symbol rate of 600 Mbps with wide channels in 5 GHz.
Those are the technical bits. I asked Kelly Davis-Felner, marketing director, how all the above plus other specifications already available and other elements coming down the pipe would be presented to buyers. The a/b/g/draft n labeling can only go so far. She said that's her primary focus right now, and there should be more news on that front soon.
The Wi-Fi Alliance won't modify its certification tests for the ratified version of 802.11n: Changes aren't needed, the group says. This was completely expected, but glad to put yet another check in a box. The 802.11n standard will finally move from draft to completed status in September, although a vote taken recently has already formally closed the process.
PC World notes, from a briefing with the alliance, that there are four optional elements to 802.11n that will be certified in the future. Those optional parts were where changes took place after the mandatory elements were settled more or less in January 2007.
The 802.11n spec celebrates its seventh anniversary without ratification: The gears at the IEEE grind but slowly, and 802.11n is still not actually a ratified and published standard even though its been built (in "draft" form) into tens of millions of devices, and has a certification standard (Draft N, natch) at the Wi-Fi Alliance. (The alliance is separate from the IEEE, developing standards for testing interoperability of commercially produced devices using the IEEE standards as the basis.)
Wi-Fi guru Matthew Gast, author of 802.11 Wireless Networks: the Definitive Guide (foreword by yours truly), writes on his marvelously named blog that 802.11n has moved up a few rungs of the IEEE hierarchical process towards shedding its draft label.
The 802.11n spec was developed in a process that started with the High Throughput Study Group, which was turned into Task Group N within the 802.11 Working Group, which specializes in wireless LAN protocols. Matthew writes that the working group has now passed the spec upwards to higher-level groups, starting with the IEEE review committee, which meets 11-September-2009. Matthew notes that's exactly 7 years after the first meeting of the high-throughput group.
In practical terms, this is all institutional process, rather than anything that will result in changes. As far as I can tell, there have been no substantive changes to 802.11n in years, and the less-important changes occur on the driver side, Matthew said via email. It's also important to note that no device has appeared that implements all the optional parts of 802.11n, and some monkeying around has occurred in those areas.
The draft label should come off in September.
Wi-Fi will expand to include new authentication methods, more enterprise support: The Wi-Fi Alliance, responsible for the brand name Wi-Fi and the certification and testing that stand behind it, will add two new authentication methods to the suite supported as part of WPA2: EAP-FAST and EAP-AKA. EAP (Extensible Authentication Protocol) is a generic method of sending messages between parties.
EAP-FAST (Flexible Authentication through Secure Tunneling) is a Cisco replacement for the long-deprecated LEAP (Lightweight EAP), which was broken back in 2004. Unlike PEAP and EAP-TTLS, popular ways of validating a WPA2 Enterprise session with server certificates and tunneling credentials, FAST uses certificates only as an option. (EAP-FAST is itself vulnerable, although those vulnerabilities can be avoided in a deployment.)
EAP-AKA (Authentication and Key Agreement) is the more critical of the two, an authentication system designed for use on 3G networks--both GMS and CDMA evolved system--with a lot of flexibility about the kind of credential that's used to authenticate a device to a network.
The alliance has long included testing of five other EAP methods, including TLS (per-device certificate), TTLS, PEAPv0 and PEAPv1, and SIM. EAP-SIM is used with 2G GSM devices.
Edgar Figueroa, the executive director of the Wi-Fi Alliance, said in an interview that EAP-AKA testing and certification goes along with the group's interest in Wi-Fi in handsets. "It's very much in alignment with our intent to continue to support convergence," he said.
Handsets need to be more capable of easily logging into Wi-Fi networks because of the constant increase in the scale of data being sent to handheld devices, coupled with the cost and limits of 3G data to subscribers. "Users may be cognizant they are paying for that data traffic really quickly if they don't get on that Wi-Fi network," Figueroa said.
I asked Figueroa about a related issue: the coming deluge of single-stream 802.11n devices which are aimed at handsets as a replacement for 802.11g. Single-stream N will use single antennas and a single radio chain, which means that the encoding speed could be much faster than 802.11g, but can't approach the 100 to 150 Mbps top rates possible with two-radio, wide-channel multi-stream 802.11n devices in laptops and base stations. (You can read more background about this in my article, "Does the iPhone Need 802.11n?", 26 March 2009.)
The potential for consumer confusion could be high, with two bands, multiple streams, and other options. "Simpler is better," he said. The alliance is discussing "how information is needed, and how much may be superfluous, and how much do we want to complicate our brand."
One item in the group's favor is that all the 802.11n devices I'm aware of that support the 5 GHz band also support 2.4 GHz. This could make 2.4 GHz the default mode for compatibility. An increasing number of consumer base stations are simultaneous dual band, too, which alleviates issues on the client side. (There may be some specialized enterprise gear that's 5 GHz 802.11a or 802.11n only.)
Unrelated to today's announcement, a minor security update is planned in the future for WPA2 to add 802.11w, which provides integrity for management frames. These specialized frames are used by access points to report various data or communicate messages without user data between an access point and client.
But, most critically, disassociation and deauthentication frames are sent in this fashion without any protection. A network attacker can disrupt a network by forging these requests, which aren't checked for validity. 802.11w uses an encryption method that prevents invalid requests from being carried out.
The minor flaw in the TKIP encryption method discovered last year won't have any impact on the security protocols or tests by the alliance, Figueroa said. "We have consistently advocated WPA2 as the protocol that people should be using"--a message echoed by all sensible security consultants, writers, and researchers.
On the enterprise side, Figueroa said the Wi-Fi Alliance had a few enterprise-oriented projects in the works with a timetable of about two years for reaching fruition.
One is WMM-Admission Control, which enhances the WMM (Wireless Multimedia) quality of service provisioning protocol (from 802.11e) with resource availability. WMM by itself allows data to be assigned one of several priority queues to ensure, for instance, that voice packets make it through.
The admission control addition would let a set of managed devices restrict a device from joining a given base station channel if the resources to support an additional call or stream weren't available. "If you allow that to happen otherwise, you end up having a non-elegant degradation for all who are using the network," Figueroa noted.
The ultimate protocol might include a form of "advice," in which a device was told a different channel to join that had resources free for what the device was intending to do.
A related future improvement is Voice-Enterprise, which will provide more robust testing of VoIP over Wi-Fi at the scale used in large networks. Currently VoIP testing by the alliance simulates a loaded network with four calls being placed; the enterprise flavor will test in a simulation of dozens of calls along with many access points in use and fast roaming among them.
Finally, Wireless Network Management will one day extend detailed network status information that's required for network monitoring and troubleshooting to network administrators. While Wi-Fi access points can report a fair amount of information today--and that varies by vendor and network design--the testing program would establish a baseline and interoperability parameters.
The nearly finished IEEE 802.11y could make Wi-Fi more practical over longer distances: Wi-Fi is a compromise. In the unlicensed bands in which it operates, it has to deal with interference from noise sources and other networks, while using very low power, and trying not to make a pest of itself. It's done very well. In the 2.4 GHz band and parts of 5 GHz, the maximum power from the radio is 1 watt (W), and the effective power (EIRP) is 4 W on an omnidirectional antenna. (You can push far more power if you narrow the antenna's beam. And parts of the 5 GHz band restrict radio power below 1 W. I wrote a long rundown of 5 GHz issues back in Jan-2007.)
But there's this lovely new segment of lightly licensed spectrum in the U.S., the 3.65 GHz band. It's a non-exclusive licensed band available only in parts of the country that don't have pre-existing ground-to-satellite or radar uses that overlap. This omits most of the eastern seaboard and most major cities; Seattle is one exception.
The licensing mechanism allows any number of operators to obtain inexpensive licenses, and register the base stations they use by location. If interference arises among base stations, operators are required to work out the problems themselves. I wrote extensively about this band and its rules on 9-May-2008 in profiling Azulstar, formerly a metro-scale Wi-Fi firm, but now a big proponent of WiMax in 3.65 GHz. I also went over the rules for the band on 11-June-2007 when the FCC announced the arrangement.
Several firms offer base station and customer premises equipment for this band now, so close to the 3.5 GHz band more commonly exclusively licensed in Europe and elsewhere. WiMax equipment is available because the 3.65 GHz band can be used with WiMax without any modifications to that protocol, although limited to just 25 MHz of the 50 MHz that the FCC set aside.
Equipment that conforms to a more stringent set of rules about contention and other factors can use the whole 50 MHz, and that's where 802.11y comes in. It's an extension of Wi-Fi to cope with the specific needs--and to open Wi-Fi technology up to 20 W EIRP, a vastly higher power output. This could allow connections over 5 km, the group says.
The Wikipedia entry on 802.11y, clearly written by someone involved with the specification, notes that three specific additions are needed: a tweak to support the way in which the FCC wants contention among competing devices to work; a method for an access point to tell a station (a connecting radio) that it's about to switch its channel or its channel's bandwidth, and the station should do likewise; and a mechanism to handle a base station allowing or revoking permission to use the spectrum without uniquely identifying the user's system or broadcasting its precise GPS-based location.
The standard is near completion and initial approval. I don't have any knowledge about whether any mainstream Wi-Fi equipment makers or metro-scale equipment makers are looking into building 802.11y into their gear.
The fact is that this could be a great technology for the mostly sub-metropolitan markets that 3.65 GHz is available in, although it has the same pain as WiMax: all new gear on the towers and all new adapters for customers.
The Bluetooth SIG says a 2009 standard will integrate Bluetooth and 802.11 in a tighter, more complementary relationship: The group that controls the Bluetooth standard continues the evolution towards agnosticism about underlying radio stuff. The latest move takes advantage of the side-by-side deployment of the "winning" wireless specifications: Bluetooth for PAN (Personal Area Networks) and Wi-Fi for WLAN (Wireless Local Area Networks). Bigger files will automatically be sent over Wi-Fi. Sounds simple, no?
"Bluetooth is great right now for sending some of these less bulky data files," said senior marketing manager Kevin Keating, but with the "bulk transfer of entertainment data, whether it's piles of MP3s or a bunch of vacation photos you want to move off your cameras or on your PC, it's not really built for that."
The SIG made this announcement this afternoon at the Mobile World Conference in Barcelona; Bluetooth is built into hundreds of millions of cell phones worldwide in its current form, and is near two billion devices shipped in all form factors. That number went from 1 to 2 billion in about two years.
The new standard, called Bluetooth High Speed, will allow a Bluetooth adapter and drivers to identify bulk transfers and move them from the lower-powered and slower Bluetooth radio technology to more battery intensive, but faster 802.11.
They're really talking about 802.11 and Wi-Fi nearly interchangably, but this standard doesn't yet have any formal involvement from the SIG's counterpart, the Wi-Fi Alliance, which controls the certification process for Wi-Fi and the trademark. Keating said, "Wi-Fi is its own brand, and we've talked."
It's important to remember that Bluetooth is both a set of profiles that define behavior--applications and schemas for data in those applications--and a radio standard. Bluetooth was originally developed with its own communications spec (the MAC and PHY, in technical terms) that worked at 1 Mbps; the 2.0+EDR and 2.1+EDR (Enhanced Data Rate) bumped that to 3 Mbps. (Version 2.1 also dramatically simplifies pairing between devices; it's rolling out widely now.)
These profiles include things like HID (Human Interface Device) for keyboards and input devices, DNP for dial-up networking, GOEP (Generic Object Exchange Profile) for file transfer, and so forth. The profiles are at a layer of abstraction above the interface and radio part, which makes it relatively simple to repurpose them across many radio standards.
In that vein, the Bluetooth SIG has already disclosed plans for its support for ultrawideband (UWB), whenever PCs with UWB or adapters start appearing in great provision, and their own ultra low power version of Bluetooth for things like heart-rate monitor, bike cyclometers sensors, and other low-data-rate devices.
The Bluetooth SIG says prototypes using the high-speed standard will be tested this year, with a published spec due in mid-2009, and devices presumably long before the end of 2009.
The Bluetooth SIG's board of directors approved 2.1+EDR (Enhanced Data Rate): The revision of the short-range personal area networking standard will reduce power consumption and greatly ease pairing, the association between two Bluetooth devices. The changes can be applied to 2.0+EDR devices via firmware, the Bluetooth SIG told me, but many Bluetooth modules are now in devices that lack firmware upgrade ability. So computers, yes; phones, many; picture frames, perhaps not so much.
Pairing has been dramatically improved by reducing the number of steps and the complexity. For devices that require a passcode entry, version 2.1+EDR requires that one device in the paired set generates a six-digit PIN that is then entered in the other device. And you're done. (Apple created their own version of this years ago, but it worked only when devices were discoverable and paired by Mac OS X to a computer, and it was far less secure than the 2.1+EDR version.)
The PIN is generated, by the way, using an Elliptic Curve Diffie-Hellman algorithm, which avoids man-in-the-middle (MitM) attacks by using an out-of-band method to confirm a key exchange. In this case, the two Bluetooth 2.1+EDR devices generate and exchange their ECDH keys, and then one device generates a six-digit PIN which is part of a hash of the session key being used by the two devices. While an MitM can talk to both parties, they can't know that six-digit PIN.
The improvement in power usage is rather significant: the SIG reports a fivefold improvement in battery life by intermittently connected devices like sensors, and input devices that send very little actual information, like keyboards and mouses.
The Bluetooth SIG will incorporate Nokia's wearable Wibree technology into its portfolio: Nokia sparked some interest when it unveiled Wibree last year because of the niche it filled: wireless technology with miserly power use that could fit in a tiny form factor, like wearable items. But there were also groans. With Bluetooth, ultrawideband, Wi-Fi, WiMax, and ZigBee already extant--not another technology standard, please!
Fortunately, Nokia is contributing Wibree to the Bluetooth SIG, and the Wibree Forum (which includes Broadcom and other firms) will become part of the fold, too. Contributing is the operative word: Nokia will allow the use of Wibree royalty free. Bluetooth itself was turned into a royalty-free offering to push its adoption.
Wibree-based products will be marketed as ultra-low-power Bluetooth, and have a goal of a year's battery life, 10-meter range, and 1 Mbps throughput. Current Bluetooth products have no battery-life target that I'm aware of, and can operate at ranges of 10 meters (Class 2) or 100 meters (Class 1), and up to 3 Mbps with Bluetooth 2.0+HDR (high data rate). Existing Bluetooth devices won't talk to Wibree equipment, but future Bluetooth standards can incorporate that ability, as Wibree uses 2.4 GHz frequency hopping radios.
This might seem to put the Bluetooth SIG in competition with the ZigBee Alliance, which products products that use the IEEE 802.15.4 standard for low-power, long-battery-life, short-range, low-speed wireless communication. (By the way, IEEE 802.15.1 is a subset of Bluetooth.) ZigBee, however, is focused on devices in the home and office like alarm and fire sensors, A/V equipment (like a TV remote control), and "white" appliances like refrigerators that might have something to say to its owner. Wibree's intent is centered around small, mobile devices where Bluetooth might be too bulky or power-intensive. We'll see if worlds collide.
Part of the Bluetooth SIG's real genius in recent years--and, yes, its director Mike Foley deserves to be credited--is embrace, adopt, extend. Bluetooth was clearly on a path to obsolescence with its specific radio technology, even as developers and hardware manufacturers continued to cram Bluetooth into everything mobile. It didn't have a good roadmap with a single offering with incremental improvements--like moving from 1 Mbps to 3 Mbps.
What's critical to know about Bluetooth is that it's a pile of specific application-layer tasks (which they call "profiles") combined with underlying radio technology. The radio technology is, frankly, irrelevant except insofar as the original and current Bluetooth standards codified a common way of exchanging low-speed data wirelessly. That's great, but there are a lot of methods, and there's nothing particularly special or important about Bluetooth's RF.
Rather, the value is in the profiles, like file transfer, printing, hands-free access, and dial-up networking. These profiles are abstracted from the radio, which means that programmers never have to think about the RF properties of the device in order to use profiles. (They might think about efficiency for bandwidth and battery usage, but not about radio-wave propagation.)
This has allowed the Bluetooth SIG to embrace ultrawideband (UWB) and Wibree without compromising its existing set of products or alienating developers. In fact, it's a boon to all electronics makers: a handset or smartphone maker could add or switch to UWB from the Bluetooth RF standard without losing Bluetooth's capabilities. (UWB is always next year's technology. Late last year, it looked like 2007 was going to be the year. But we're still waiting for the first real UWB products to hit the marketplace.)
The 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.
The Wi-Fi Alliance says that nearly 100 handsets are certified: The group has certified 82 dual-mode handsets and 10 Wi-Fi-only phones. The idea of certifying voice handsets that incorporate Wi-Fi allows the alliance to ensure both interoperability and better performance. Frank Hanzlik, the alliance's executive director, said in an interview that this testing helps the manufacturer produce devices that function better in difficult RF environments, as well as align the phone's function relative to Wi-Fi gateways. The alliance has also been working closely with the CTIA, the cell industry's trade group.
Hanzlik said that he has been working to raise awareness of the WMM (Wireless Multimedia) extensions that allow voice packets to achieve priority across a network, WPA2 security, and the special WMM Power Save mode, which can extend battery life by 25 to 40 percent on a handset through better management of unnecessary communications with a gateway. Hanzlik expects over time to see WMM and WMM Power Save in more gateways. WMM Power Save could be a simple upgrade for most routers, as it requires no changes in the radio. Incompatible power save modes can actually waste power, and the alliance would like all makers to move towards their certified version.
For large-scale hotspot networks, moving to WMM Power Save could dramatically improve the experience of mobile users making Wi-Fi calls. "When you look at these very, very large operators like T-Mobile here in the US, or some of the folks in the Wireless Broadband Alliance [a worldwide consortium of hotspot operators], we're trying to get the word out to these folks" to upgrade their networks or plan to include WMM Power Save from the beginning.