Electronic Design

Cut The Cord With WiMedia

If you’re anxious to see the latest in wireless technologies and find out how you can use them in your next design, then the International CES is the place to be—especially for the latest in Ultra-Wideband (UWB) products. This short-range technology provides speeds up to 480 Mbits/s at up to 10 m.

UWB has been around a few years, but it hasn’t gotten much traction as a widespread wireless technology yet. It has taken a while to firm up the standard and put out chips that can be embedded into other products. Several factors have contributed to this slow-to-market wireless option.

One of these is the challenge of making OFDM chip sets that cover the 3.1- to 10.6-GHz band allocated to UWB by the FCC. The early products focused on the three lower bands from 3.1 to 4.7 GHz. Many such chip sets were created, and today, most of the main semiconductor vendors are offering second-generation products, mostly in full CMOS but a few yet with biCMOS SiGe.

Another factor has been the high price of these chip sets. Of course, like all other solid-state devices, prices will begin to drop as volume increases. That volume has been growing slowly, but there is a clear sign of greater adoption.

The confusing and conflicting worldwide spectrum allocations for UWB also limit adoption. These allocations vary widely from country to country so it has been hard to make chip sets that fit all countries. On top of that, there are still countries trying to firm up their UWB assignments.

Only one group of bands is valid worldwide, but that may be changing as new rules and regulations come out of Asia and Europe. A new technology called Detect and Avoid (DAA) also may help as it is adopted, as it enables UWB products to avoid conflicts with other services in the same spectrum. Most new chip sets incorporate DAA.

As these challenges are met, the big problem is getting greater visibility for the technology. That has been the job of the WiMedia Alliance, the organization that sets the standards, performs certification tests for product compatibility, and promotes the technology. With the standard firmly in place and many certified products, WiMedia’s job is primarily educational, letting the engineering community know just what UWB offers.

UWB is a great wireless technology, as it has one of the highest data rates of any of the current crop of wireless standards. It can handle up to 480 Mbits/s at ranges of about 2 to 3 m. The max range is about 10 m, but speed typically drops to less than 100 Mbits/s at that range. Yet that is still faster than most other offerings. Range is limited by the very low power requirement of –41.3 dBm/Hz of bandwidth, which is what keeps UWB signals from interfering with other overlapping services in the spectrum.

Currently, the greatest use of WiMedia UWB is wireless USB dongles and hubs. It works great as a cable replacement. The USB Implementer’s Forum standard protocol rides on the WiMedia MAC and PHY. Dozens of WiMedia USB products are out there now, and you should see some new ones at CES. Even some laptop manufacturers are embedding wireless USB.

UWB is also being adopted in a variety of wireless video products (Fig. 1). UWB can be used to connect the set-top box to the HDTV set and to the digital video recorder. Even wireless HDMI is available (Fig. 2). Audio is another application, with products now available for connecting surroundsound 5.1 components around the room. Even digital cameras and camcorders now use UWB to connect without wires.

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