SAN JOSE, Calif. In the race to a gigabit-per-second wireless link for the digital home, some ultrawideband backers are gasping for air while Wi-Fi proponents are revving up for the next lap.
An IEEE 802.11 study group is gearing up to launch a standards effort next year that could pave the way for Wi-Fi to step up to 3-5 Gbits/second data rates. Meanwhile an independent tester reports two UWB products now shipping have average throughput of just 20 Mbits/second at a range of 15 feet.
"We are finding throughput is quite disappointing," said Fanny Mlinarsky, an industry expert in wireless test. "There is nothing above 50 Mbits/s maximum, and the average is 20 Mbits/s. Everyone thought this was going to be the short-range Gbit network," she said.
Mlinarsky's lab, Octoscope, is conducting tests of shipping UWB systems sponsored by UWB vendor Pulse~Link Technologies. So far, companies shipping UWB silicon have declined to participate in the tests, many citing the fact a competitor is sponsoring the program. Jack Shandle, editor of sister Web site Wireless DesignLine, has publicly called on UWB chip makers to participate in the tests, so far without effect.
Vendors said inefficiencies in today's media access controller chips and software drivers are inhibiting throughput, something that should be cleared up in future products. Mlinarsky plans to acquire a LeCroy tester to check the physical layer performance of the systems.
"We are getting less than a tenth of the PHY data ratethat can't be all MACs and drivers," she said.
Octoscope tested systems from Belkin and IO Gear using chips from Alereon, Freescale, Intel and NEC. It plans to test Toshiba systems using other silicon this week. Pulse~Link did not ship its test chips to Octoscope before fires swept through the San Diego area this week, cutting off some communications.
Mlinarsky believes the orthogonal frequency-division multiplexing technology used in the wireless USB version of UWB may be the culprit.
"Everyone joined Intel in the WiMedia Alliance before they did due diligence on the technology," Mlinarsky said. "OFDM is not the optimal choice at these low power levels, so the industry may have made a mistake," she added.
Companies doing their own tests of UWB silicon agree that performance of the parts is so far unacceptable.
"I haven't seen anything I want to build a product around. We can't afford to design in a 1W radio to get less than 100 Mbits/s over a few feet," said a senior technology manager at a cellphone company who asked not to be named.
The UWB problems may be just a passing storm, said wireless analyst Craig Mathias of Farpoint Group (Ashland, Mass.). But the problems need to get addressed soon or other technologies such as advanced Wi-Fi or emerging 60 GHz radios will steal UWB's thunder, he added.