Bluetooth SIG backs Wi-Fi as fast WPAN choices proliferate

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.