When Wisair won the contract to be at the heart of Belkin's ultrawideband-based Cable-Free USB Hub and dongle—the first such product on the market—it was a bit of a mixed blessing. For sure, winning the design socket was a coup, but the circumstances were a bit less than ideal.
The main drawback—or challenge—was that the form factor of the hub had already been determined by Belkin. It was originally based around a direct-sequence UWB chipset from Freescale that wasn't delivered. The second challenge came from the market and peer pressures that Wisair faced as it implemented the design. As the first widely available consumer device to be based on the multiband orthogonal frequency division multiplex (MB-OFDM) form of UWB being proposed by WiMedia, the onus was clearly upon the design team to make it the best design they could to reinforce that standard, as well as Wisair's already strong standing among its peers.
"This was the very first implementation and we wanted to ensure the best quality," said Serdar Yurdakul, director of marketing and business development at Wisair (Los Gatos, CA). With regard to the form factor, David Menshulam, Wisair's vice president of engineering, said the biggest challenge was the predetermined profile. "We had to have everything in, including the internal antennas and filtering and still get the performance [Belkin needed]."
Figure 1: Belkin's slick box design meant Wisair had to contend with a low profile and no external antennas.
So how'd it fare?
To see how well Wisair overcame the challenges I did some tests. The kit comes with the HWA531 USB dongle, a sleekly designed 4-port USB hub, an optional docking station for the USB dongle and the appropriate driver software. The advertising on the package promoted ranges of 30 ft. and file download rates of "up to 480 Mbits/s." The former is credible, the latter has to be taken for what it is: over-zealous marketing. Few in their right mind would expect that from the very first such UWB implementation.
The set-up was fairly straightforward, though I ended up ignoring the manual in the end due to endless redundancies. Anyone familiar with installing new equipment would be better off following their instinct: install the software, reboot, connect the equipment and follow the install wizards from there, using the manual only for quirks like enabling the hub via the system tray.
For peripherals, I chose a Canon Eos Rebel digital SLR and a Maxtor OneTouch back-up drive. The camera connected fine, but connecting the Maxtor caused my system (IBM Thinkpad) to crash. Wisair suspected that it might be a setting on the Maxtor that initiated a back-up too quickly, before the hub had a chance to register the peripheral. In any case, I tried a Western Digital 250-Gbyte My Book external hard drive and that connected first time. For the tests, I chose the My Book as the data source given the access-speed limitations of the camera's compact flash storage. For test files, I used multiple JPEG images that amounted to 50.2 Mbytes, or 401.6 Mbits. The tests were performed in a single room, as UWB's low power and high frequencies do not make it suitable for inter-room communication. The test ranges were 1, 6, 12, 20 and 30 ft. Three measurements were made for each test range and the average was calculated.
With the dongle inserted in the docking station and the transmit rate set to 'auto', the averaged data rates at the given ranges were 29.7, 32.18, 30.3, 28.7, 24.6 Mbits/s. It's important to note that this is the actual payload rate, not factoring in the USB/WiMedia overhead, which would increase the overall throughput. With the dongle attached to the laptop directly, the data payload rates were 30.9, 22.5, 20, 17.9 and 12.5 Mbits/s, respectively.
All in all, the data rates seem to be currently on a par with 802.11g, which touts 54 Mbits/s but has a typical payload rate of between 30 and 39 Mbits/s. Not bad for the first implementation of a new technology, though it's still a long way from the goal of an overall throughput of 480-Mbits/s and at $200 it's still on the pricey side.
