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Wi-Fi certification for voice devices

In news that is huge for VoWi-Fi, the Wi-Fi Alliance announced on June 30th a new certification program, “Voice-Personal.” Eight devices have already been certified under this program, including enterprise access points from Cisco and Meru, a residential access point from Broadcom, and client adapters from Intel and Redpine Signals.

Why is this huge news? Well, as the press release points out, by 2011 annual shipments of cell phones with Wi-Fi will be running at roughly 300 million units. The Wi-Fi in these phones will be used for Internet browsing, for syncing photos and music with PCs, and for cheap or free voice calls.

The certification requirements for Voice-Personal are not aggressive: only four simultaneous voice calls in the presence of data traffic, with a latency of less than 50 milliseconds and a maximum jitter of less than 50 milliseconds. These numbers will produce an acceptable call under most conditions, but a network round-trip delay of 300 ms is generally considered to approach the limit of acceptability, and with a Wi-Fi hop at each end running at the limit of these specifications there would be no room in the latency budget for any additional delays in the voice path. The packet loss requirement, 1% with no burst losses, is a very good number considering that modern voice codecs from companies like GIPS can yield excellent sound quality in the presence of much higher packet loss. This number is hard to achieve in the real world, as phones encounter microwave ovens, move through spots of poor coverage and transition between access points.

Since this certification is termed “Voice-Personal,” four active calls per access point is acceptable; a residence is unlikely to need more than that. Three of the four access points submitted for this certification are enterprise access points. They should be able to handle many more calls, and probably can. The Wi-Fi Alliance is planning a “Voice-Enterprise” certification for 2009.

There are several things that are good about this certification. First, the WFA has seen fit to highlight voice as a primary use for Wi-Fi, and has set a performance baseline. Second, this certification requires some other certifications as well, like WMM power save and WMM QoS. So far in 2008, of 99 residential access points certified only 6 support WMM power save, and of 52 enterprise access points only 13 support WMM power save. One of the biggest criticisms of Wi-Fi in handsets is that it draws too much power. WMM power save yields radical improvements in battery life – better than doubling talk time and increasing standby time by over 30%, according to numbers in the WFA promotional materials.

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Is 802.11n too power-hungry for handsets?

Most 802.11n access points draw more power than Power over Ethernet (PoE) can supply, while 802.11a/b/g access points work comfortably with PoE. So 802.11n must be more power consumptive than 11g, right?

The answer is yes, but when you delve into the reasons why you may discover that an 802.11n handset can still have comparable, or better battery life than an 802.11g one.

The big power drain for 802.11n is MIMO, for two reasons. First, MIMO demands a separate radio transmitter for each of its channels. In the Farpoint white paper linked above, testing was done with six transmitters – 3 at 2.4 GHz, 3 at 5GHz. The 11n specification allows up to 4 MIMO channels, and Wi-Fi certification requires at least two. Each of these transmitters burns as much power as the single (or dual in the case of an a/g AP) transmitter in an 11a or 11g access point. A second increase in power demand by 11n comes from the increased processing load not just because of the increased number of channels, and not just because of the increased data throughput, but also because each individual MIMO stream places a heavier processing load than a single 11a or 11g stream.

But the Wi-Fi Alliance (WFA) has waived the MIMO requirements for handsets, allowing 802.11n certification for single-radio devices. So none of these increases in power dissipation needs to apply to handsets.

Single-channel 802.11n still requires more processing than single channel 802.11g, because of advanced features like STBC and LDPC, but STBC and LDPC are amenable to hardware implementation (which reduces their power demand), and these and other advanced features of 802.11n improve “rate at range,” meaning that the transmitter is active for shorter times, and can transmit at lower power.

The net is that Redpine Signals, a pioneer of 11n for handsets, claims that a handset using the Redpine 11n chip actually has better battery life than it would with a competitor’s 11g chip.

Wi-Fi state of the art is a rapidly moving target, and over the past 12 months there have been startling improvements in power efficiency. I have written here about the new Atheros chip, for example. So if the latest 11g handset chips are more power efficient than 11n competitors, it is more a function of their recency than their adherence to 11g.

The benefit of 5 GHz operation is compelling for Voice over Wi-Fi, and it will be hard for handset vendors to promote the decade-old 802.11a over 802.11n. 802.11n is already the Wi-Fi flavor of choice for access points and PC clients, and it soon will be for handsets, too. How soon? It’s hard to say. So far the only chip vendors to announce 11n for handsets are TI, Redpine Signals and Conexant, and Conexant exited the handset Wi-Fi business just two months after it announced this chip. No phone is yet shipping with 802.11n although TI said it was sampling its WiLink 6.0 with 11n in February 2007. The Wi-Fi alliance has not yet published its Handheld profile for 802.11n certification. On the other hand, ABI research in September 2006 predicted that the majority of the 300 million Wi-Fi enabled handsets to ship in 2011 will support 802.11n.

If 802.11n handset shipments fall short of this prediction, it won’t be because of battery life considerations.

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Wi-Fi Bluetooth collision

I already wrote about how Bluetooth is specifying Wi-Fi for its high bandwidth transport in a future version. Now there’s another interesting Bluetooth/Wi-Fi juxtaposition.

You may remember that last year Bluetooth subsumed WiBree as an ultra low power consumption variant. Now something analogous is happening in Wi-Fi, where a startup called Ozmo has come up with an ultra low power variation of Wi-Fi, which it is pitching as a substitute for Bluetooth.

Ozmo is not the first to propose this. Nanoradio claims that its implementation of Wi-Fi consumes way less power than Bluetooth, and they have a reference design for a Wi-Fi headset to demo the concept. Atheros has also recently announced a low-power Wi-Fi chip – so low that they claim “near zero” stand-by power consumption.

So Ozmo may not be so radical in its low-power claims, but it also claims low-cost. The Ozmo chip is priced the same as Bluetooth chips, which Ozmo estimates are between 1/4 and 1/3 the cost of Wi-Fi chips.

The Atheros and Nanoradio chips are full implementations of Wi-Fi; Ozmo’s is, according to this EETimes article, a “stripped down” version. This may mean that it is a non-standard version, in which case it would need a new certification program from the Wi-Fi Alliance – not a major obstacle, I presume, in view of Intel’s strong support for Ozmo.

So why would anybody want a version of Wi-Fi to substitute for Bluetooth, when we already have Bluetooth? Well, while most phones come with Bluetooth these days, in the PC world Wi-Fi is far more common than Bluetooth. So for peripherals designed exclusively for PCs, like mice and keyboards, Wi-Fi makes more sense than Bluetooth simply on the grounds of out-of-the-box compatibility. Add the technical benefits, like coexistence (Bluetooth and Wi-Fi tend to step on each others’ toes) and superior performance (Ozmo claims double the battery life in similar applications to Bluetooth), and it seems like a no-brainer.

The factors that could cause it to fail are ease of use and price. The setup of the peripherals with the PC must be completely automatic, and the operation of the devices must be flawless. Peripheral manufacturers must produce Wi-Fi versions of all their wireless products, and price them the same as their Bluetooth versions. The Wi-Fi drivers on the PC side will have to be modified in order to permit the PC Wi-Fi to communicate simultaneously with access points and peripherals. This is being done anyway by Intel, in a project called “Cliffside.”

All these impediments are mitigated considerably by Intel’s involvement. Intel makes most of the Wi-Fi chips in PCs, and presumably these chips will support the Ozmo products. With this assurance, peripheral manufacturers will feel comfortable going ahead with Ozmo-powered products.

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802.11n update

There’s some FUD around 802.11n. A comment on this blog wonders how long it will be before it is ratified, and calls it a “pipe dream.”

So I was pleased to hear an aside from a Cisco executive in the webinar about the new Cisco Mobility vision. A participant asked Brett Galloway if delays in the ratification of 802.11n are holding back deployment. He responded:

We don’t see it. Technology adoption is a cycle. Late adopters are more conservative. Large numbers of 11n clients are shipping. The driver is Wi-Fi Alliance Draft N certification. There is comprehensive agreement around the ecosystem for interoperability testing using the WFA testbed. Cisco announced recently that it had shipped 50,000 11n access points.

The critical point here is that a final 802.11n specification is not needed for successful deployment. The main thing you want from a Wi-Fi device is that it is interoperable with all the others, and that’s what the Wi-Fi Alliance Draft N certification delivers – at least to the same extent that 11g devices are interoperable.

While 50,000 is a trivial number in the context of Wi-Fi access points, remember this is just enterprise-grade APs, and doesn’t include anything from Cisco’s Linksys division. When the litigation goes away and the final specification is published, all the access points out there are likely to be upgradable with a download. So go ahead and enjoy the benefits of 11n like so many other people are doing.

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Cisco’s Motion Announcement

Cisco’s Motion announcement on May 28th was huge for enterprise mobility. It defined some new terms which we will be hearing a lot: “Cisco Motion,” “Mobility Services Architecture” and “Mobility Services Engine.” Cisco Motion is the name of the “vision.” The Mobility Services Engine 3350 is a $20,000 appliance that embodies the Mobility Services Architecture, which is a part of Cisco’s Service Oriented Network Architecture.

Cisco has published a lot of useful information about these new products. A good place to start is the launch webinar, which includes an informative Powerpoint presentation. The Mobility Services Architecture is described in a white paper. There are two press releases: a conventional press release consisting of written words, and a “social media release” consisting of links to YouTube clips and podcasts.

What we’re doing here is abstracting the network control element of the architecture and the services and application integration piece. This reflects what we have been talking about for the last 2 plus years around the Services Oriented Network Architecture. It’s about how we can drive new capabilities into the network, that can be married up with a host of different applications and turned into a solution for our customers. It’s not just applications running over the network. Increasingly with this architecture, it is about applications running “with” the network.

Ben Gibson, Senior Director Mobility Solutions, Cisco Systems

Cisco describes the MSE as a “platform for partnering,” the idea being that it exposes network-level information through an open application programming interface (API) to applications delivered by independent software vendors (ISVs).

Adding wirelessness to the IP world generates network-layer information that can be useful to applications, notably information about the location of known devices, and the intrusion of unknown devices. The MSE orders that information and presents it through the API.

Cisco Motion also addresses some downsides of mobility. Adding mobility to the IT world brings a lot of new headaches:

  • There are multiple network types (currently cellular and Wi-Fi, later WiMAX)
  • There is a profusion of new device types (currently smart phones) which must be managed and tracked
  • There is a wave of innovation in consumer applications. Employees are demanding these applications in the enterprise environment.
  • Mobility also complicates compliance with data confidentiality regulations like PCI and HIPAA.

So far Cisco has identified four categories of application that can run on the MSE: Context-Aware applications, Wireless Intrusion Prevention Systems, Client Management and Intelligent Roaming.

Context Aware Applications
“Context Aware applications” seems to be Cisco’s term for applications that do asset tracking. Cisco is partnering with ISVs in both horizontal and vertical markets. These ISVs are OAT, Intellidot, Aeroscout, Pango/Innerwireless and Airetrak. The Context-Aware software is scheduled to ship in June 2008.

Adaptive Wireless Intrusion Prevention Systems

Overlay wireless intrusion prevention systems add devices to monitor wireless traffic looking for rogue access points and clients. The innovation here appears to be that the MSE exposes information from the access points and wireless controllers that eliminates the need for these overlay devices. IPS software running on the MSE can substitute for the overlay IPS, while yielding equivalent depth of reporting and features. A further benefit of running the IPS over the MSE API is that the same software will be able to handle future wireless networks in addition to Wi-Fi. The Adaptive WIPS software is scheduled to ship in the second half of 2008.

Mobile Intelligent Roaming

This is enterprise Fixed-Mobile Convergence. The MSE isn’t a mobility controller; it issues an event up through the API when it determines that the Wi-Fi network needs to hand the call off to the cellular network. This event is handled by mobility controller software from an ISV. Cisco’s launch partners for this are Nokia for phones, and Agito on the mobility controller side. The Mobile Intelligent Roaming software is scheduled to ship in the second half of 2008.

Secure Client Manager

This works with Cisco’s 802.1X and CCX products. Cisco estimates that 80% of IT’s wireless and mobility effort goes to client troubleshooting and security provisioning. The Secure Client Manager will help mitigate this problem for the imminent wave of mobile devices. The Secure Client Manager is scheduled to ship in the first half of 2009.

Unified Wireless Network Software

Cisco Motion requires a new software load for the access points and WLAN controllers: the Cisco Unified Wireless Network Software Release 5.1, which shipped in May 2008.

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Ask and ye shall receive

Ken Dulaney, Gartner VP distinguished analyst and general mobile device guru, told the crowd at the Gartner Mobile & Wireless Summit today that he still can’t recommend businesses adopt the iPhone — even with an SDK. Dulaney said that he recently wrote Apple a letter in which he outlined several things Apple would need to do with the iPhone before Gartner could change its mind about it. The directives included:
– Permit the device to be wiped remotely if lost or stolen
– Require strong passwords
– Stop using iTunes for syncing with a computer
– Implement full over-the-air sync for calendar and PIM

Jason Hiner, TechRepublic March 5th, 2008

On the same day Dulaney said this in Chicago, Phil Schiller of Apple was holding a news conference in Santa Clara granting some of these wishes, and many more:

  • Microsoft Exchange support with built-in ActiveSync.
  • Push email
  • Push calendar
  • Push contacts
  • Global address lists
  • Additional VPN types, including Cisco IPsec VPN
  • Two-factor authentication, certificates and identities
  • Enterprise-class Wi-Fi, with WPA2/802.1x
  • Tools to enforce security policies
  • Tools to help configure thousands of iPhones and set them up automatically
  • Remote device wiping

At the news conference Apple wheeled out several corporate endorsers: Genentech, Stanford University, Nike and Disney.

At first blush, the new enterprise-oriented capabilities of the iPhone appear to be an IT manager’s dream come true (though it will be a while before the dream is a reality.) Even this contrarian post concedes that it will make the iPhone more competitive with the Blackberry, while faulting Apple for not having a comprehensive enterprise strategy.

Apple is clearly serious about the enterprise smartphone market, and this strategy is sound. The business market supports price points that easily accommodate the iPhone, and this strategy spills over to the business PC market in two ways: today by acting as a door-opener for Mac sales, tomorrow by evolving the iPhone into a PC replacement for many users.

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Bluetooth over Wi-Fi

The Bluetooth SIG put out a press release the other day saying that by mid-2009 a specification that includes Wi-Fi as an “alternate MAC/PHY” will be released.

This is the relevant part of the release:

What we’re doing is taking classic Bluetooth connections – using Bluetooth protocols, profiles, security and other architectural elements – and allowing it to jump on top of the already present 802.11 radio, when necessary, to send bulky entertainment data, faster. When the speed of 802.11 is overkill, the connection returns to normal operation on a Bluetooth radio for optimal power management and performance.

So this innovation specifies an interface above the Bluetooth MAC layer that enables Bluetooth session data to flow through a Wi-Fi radio instead of a Bluetooth one.

The press release says that the Alternate MAC/PHY will be used to do things like:

Wirelessly bulk synchronize music libraries between PC and MP3 player.
Bulk download photos to a printer or PC.
Send video files from camera or phone to computer or television.

But the new specification will only be useful in devices that already have both Wi-Fi and Bluetooth, and Wi-Fi can do these things without any assistance from Bluetooth. So the increment in value may be small; but Bluetooth can still bring something to the table. According to Wikipedia,

The Bluetooth Radio will still be used for device discovery, initial connection and profile configuration, however when lots of data needs to be sent, the high speed alternate MAC PHY’s will be used to transport the data.

It seems oddly limiting not to go the whole way, and enable Bluetooth applications to run on top of Wi-Fi even when there is no Bluetooth radio.

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Potential security vulnerability in some Wi-Fi handsets

George Ou of ZDNet reports that the 802.1X authentication techniques used on some Wi-Fi handsets may be vulnerable. The problem is that these handsets may not validate the certificate from the authentication server. This design choice speeds up roaming, but means that the handset could disclose user login credentials to a sophisticated, determined attacker. Ou suggests using WPA-PSK with a long password instead of 802.1X with these handsets.

Vocera’s documentation, which Ou references, has more depth on the performance trade-offs of various Wi-Fi security options.

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Low power 802.11n sampling from Redpine

Redpine Signals has announced that it is sampling a low power 802.11n chip suitable for cell phones. A reference design was certified in January, making it the first handset-grade 802.11n chip to market.

One of the major benefits of 802.11n is MIMO, so you might think that since a handset is unlikely to have multiple antennas, 802.11n isn’t going to help much. Actually, it will make an enormous difference in reliability and range, and consequently throughput. I wrote before about the array of improvements incorporated in 11n. The one of greatest interest in this context is Space-Time Block Coding (STBC).

The WFA website shows 90 Access Points (APs) certified for 802.11n, but STBC is optional in 11n, not mandatory, and not all the AP chipsets support it. The main makers of AP chipsets are Atheros, Broadcom and Marvell. None of these have mentioned STBC until recently. But now Broadcom says it is in the BCM4322, which is set to ship in the first quarter of 2008, and Marvell says it is in the TopDog 11n-450, which is scheduled to ship in 2Q 2008.

This Techworld article has a good discussion of the current state of enterprise 11n access points, noting that multi-radio APs are currently too power-hungry to be powered over Ethernet (PoE).

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Dual mode phone trends – Update

In May 2007 I showed a chart of dual-mode phone certifications by time. Certifications have continued to grow since then, as the updated graph below shows. These numbers are pretty raw, for example six certifications in November 2006 were for variations on a Motorola phone first certified in October. If you go back and look at the previous chart you will also notice discrepancies in the number of certifications for any particular month. These are presumably because of revisions at the WFA website.
Dual mode phone trends
From 2006 to 2007 smartphone certifications were essentially flat, going from 33 to 36, while feature phone certifications went from 11 to 21. These add up to 44 dual mode phone certifications in 2006 and 57 in 2007.