Bluetooth SIG backs Wi-Fi as fast WPAN choices proliferate
Turns to 802.11n
Comment Controlling the technology that will underpin the next generation of fast wireless networks, especially for the multimedia home and HDTV, will be a critical competitive advantage, and the jostling for position is already starting.
IBM and others are putting their weight behind 60GHz options, and the Wi-Fi community is examining gigabit options, but for the nearer term, 802.11n Wi-Fi and UltraWideBand (UWB) are the main emerging options for high speed, short range connections.
UWB wins the day on performance and low power usage, provided distances are kept short, but with the once tortured 802.11n standards process now approaching resolution, UWB is in danger of falling behind in terms of commercial availability.
This is because of two factors – although several regulators, including those in the European Union, US, and Japan, have now opened up to UWB, there are many more decisions to be made before it becomes universal like Wi-Fi; and there are now some doubts over its actual performance in commercial platforms, which could delay the volume commitment from chipmakers and OEMs that is required to achieve the brutally tight economics of embedded personal area wireless.
Bluetooth over Wi-Fi
One sign that fast Wi-Fi is edging ahead of UWB in time to market terms is a decision by the Bluetooth Special Interest Group (SIG), which controls the short range, mid-speed standard, to create protocols that will enable Bluetooth to use Wi-Fi as a transport.
The SIG had previously committed to developing its proposed high speed option using UWB – and specifically, the WiMedia standard implementation backed by most of the PC and consumer electronics sectors – as the transport, but now wants to offer an 802.11n choice as this is making better progress in getting into handsets (though currently in a pre-standard version).
This is presented by the group as a stopgap option before their first choice is fully launched, but if Bluetooth over Wi-Fi is widely adopted, that may shrink, or at least delay, the addressable market for a UWB version, except in applications that require extremely high speeds.
"We have got to be realistic," said John Barr, chairman of the SIG's board of directors, and director of standards realisation at Motorola. "UltraWideBand silicon vendors are not delivering anything close to what they have promised."
He told the Bluetooth Evolution conference in London last week that Motorola had shifted its focus because of UWB delays and is seeing rising demand for Wi-Fi in mobile devices. Since Motorola has not taken a major role in the WiMedia Alliance, whose technology was originally opposed in the standards bodies by a rival from former Motorola chip unit Freescale, it may also see 802.11n as an option over which it can have more influence.
Teething problems for WiMedia?
The main progress made by WiMedia so far have been in Wireless USB, where it is the base standard, but which has mainly impacted on the PC market rather than handsets so far. Artimi and other UWB specialists claim there will be Wireless USB handsets in Asia by mid-2008, including from Korea's SKT.
However, doubts were recently cast over whether UWB, in its OFDM-based WiMedia incarnation – which works within regulatory limits that significantly restrict the potential performance of unfettered UWB – is living up to its performance claims.
An independent testing lab, Octoscope, claims the UWB products that are currently shipping have average throughput of only 20Mbps over 15 feet, rather than the 480Mbps peak that is promised. "We are finding throughput is quite disappointing," said wireless test expert Fanny Mlinarsky. "There is nothing above 50Mbps maximum, and the average is 20Mbps. Everyone thought this was going to be the short range Gbit network."
The lab tested systems from Belkin and IO Gear, using chips from Alereon, Freescale, Intel and NEC. The chipmakers refused to participate directly in the tests, pointing out that they are sponsored by a UWB company promoting its own implementation rather than WiMedia – Pulse~Link.
The two vendors said the poor results were down to inefficiencies in the MAC chips and software drivers, but these flaws were being fixed for the next products – an explanation that Mlinarsky found unconvincing given the low PHY data rates.
She believes the use of OFDM is a poor choice at such low power levels and may be inhibiting performance. She told EETimes: "Everyone joined Intel in the WiMedia Alliance before they did due diligence on the technology. The industry may have made a mistake."
HDTV over UWB:
Pulse~Link is one vendor that believes this to be true, although it has a different focus to most of the WiMedia members, with heavy emphasis on HDTV, and on running UWB over both wired and wireless media, and over Lan distances.
Another HDTV over UWB specialist is Tzero, which is sampling silicon delivering data rates of 1Gbps or less, assuming some compression of HD video. Tzero is targeting Lan distances for HDTV signals over UWB, and is part of the Wireless HDMI Alliance, which is developing standards for a wireless version of the HDMI interface, largely using a specification created by TZero and Analog Devices. This works with any devices with HDMI plugs and compresses video using JPEG 2000.
Motorola, Phiar and 60GHz
Meanwhile, other high speed, low power options are starting to emerge. As well as pioneering work from SiBeam, IBM, Toshiba and others in 60GHz radios, other start-ups like NewLans are innovating in this area, where the IEEE is to commence a standards process for personal area networks next year.
Now Motorola has joined the race, having failed to dominate UWB with the technology, DS-UWB, that it created when it still owned Freescale. Motorola Labs has a joint development agreement with Colorado-based Phiar, and the partners have succeeded in using metal insulator electronics instead of semiconductors for 60GHz WPAN devices.
Motorola says its semiconductor-free radio will be a direct challenge to the products under development by IBM, which will use its silicon germanium BiCMOS radios. Metal insulator electronics are low cost and can be fabricated on standard CMOS lines on top of ultra-cheap plastic substrates. Motorola also said the prototype Phiar-based devices have higher performance than their benchmark devices, and conform to the preliminary specifications laid down by the IEEE's 802.15.3c 60GHz standards working group.
Other companies developing 60GHz WPAN chipsets include the WirelessHD consortium (LG Electronics, Matsushita/Panasonic, NEC, Samsung, SiBeam, Sony and Toshiba); STMicro; Bridgeway Systems and TeraBeam.
Other approaches to fast Wpans
Alternative approaches come from specialists like Amimon and Radiospire. The former uses a souped-up variant of 802.11n to provide a wireless high definition interface for HDTV, running at 1.5Gbps. About 80 per cent of the Amimon system is based on core 802.11n technologies— a 5GHz radio with OFDM modulation and a 4x5 MIMO antenna array. The chips will initially be 50-100 per cent more expensive than standard 802.11n chipsets, but could come down to the same price levels within two to three years, the company claims. It says a pair of baseband and RF chips will consume less than 5W and cost less than $50 from day one.
Amimon uses an approach it calls joint source-channel coding to squeeze faster data rates out of 802.11n technologies which typically deliver 100-500Mbps. Using a 20MHz channel, the system can deliver 1.5Gbps, and in markets where channel bonding is allowed, the speed can be increased to 3Gbps in a 40MHz channel for HDTV resolutions of 1080 progressive scan.
Radiospire uses tweaked versions of WiMAX and Wi-Fi. Its chips operate in the 3.1GHz-4.8GHz range to avoid interference with 802.11. Radiospire claims to retain wired image quality with its HDMI chipset, which enables wireless HDTV connectivity without compressing the video signal. The technology supports 720p, 1080i and 1080p HDTV formats with industry standard HDCP encryption and throughput is up to 3Gbps for 1080p formats. Its chipset consists of a SiGe RF transceiver chip, ADC/DAC, and a CMOS baseband device.
Most of these individual players will need to attract the attention of large OEMs or standards bodies to survive. They will no doubt be targeting the IEEE's 802.11 Very High Throughput study group, which is looking at Gigabit Wi-Fi and has heard presentations from AT&T, Intel, Motorola, Nokia and start-up Wilocity, among others, and is likely to launch a formal standards effort as early as January.
One presentation focused on building 3-gGbps products in the 5GHz band that could be used in wireless links to monitors, projectors and video cameras, markets that are targeted by UWB.
Some Wi-Fi enthusiasts are also starting to lobby regulators on plans for very high frequency bands, notably 275GHz to 1THz. AT&T has criticised European Union plans to exclude Wi-Fi from such bands. "The best terahertz spectrum is being carved up among science, satellite and amateur radio interests. The giveaway of this precious spectrum is unexpected, capricious and irreconcilable with the evolution of future broadband wireless networks," David Britz of AT&T said in his presentation to the IEEE study group. Phiar and other start-ups are already working on terahertz receivers.
Copyright © 2007, Wireless Watch
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