26 July 2006

UWB: Simple Wireless Connectivity

Both consumers and manufacturers of electronic equipment can appreciate the simplicity of ultra-wide band (UWB). Not only will UWB enable the world to discard the masses of wires from around its desks, but its use of a single radio platform to support multiple protocols will also simplify design decisions for manufacturers and make connectivity issues transparent to consumers.

UWB will be suitable for use with PDAs, mobile phones and in-home connectivity applications – allowing a TV to talk to a DVD player, for instance. But it could also be used in anything from radar and federal communications to precision location tracking, security, medical and industrial wireless applications.

UWB has been a hot topic for quite some time, but recent availability of chipsets and the completion of a USB protocol stack for UWB suggest that it is about to make a real impact. So what is it, exactly, and what resources are available for designers?

A Single Radio Platform
UWB is a term covering a class of radio technologies using the 3-10GHz frequency band. Its proponents view it as a universal wireless platform, capable of transmitting a certified wireless form of USB, IEEE1394, TCP/IP and next-generation Bluetooth from a single radio subsystem, which means that consumers will no longer have to buy a number of different radios just because their wireless products happen to use different protocols.

This has positive economic benefits for manufacturers, who will only need to incorporate one radio platform in PCs and portable electronics, which will drive down the cost of the solution.

Use of a single shared radio platform also allows consumers to avoid the problem of different wireless standards interfering with one another – high-speed Bluetooth and certified wireless USB, for example.

Faster Wireless Transfers
Wireless connectivity solutions already exist, but they are not fast enough for consumers who want to transfer, say, MP3s or digital images in an instant. Emerging under the umbrella of UWB, the new solutions are poised to address this demand using new coding technologies at higher frequencies to provide 480Mbps links over short distances. This will allow more data to be transferred in a shorter period of time using less power per byte than before.

UWB will improve Bluetooth throughput considerably to enable file transfers that are much faster and use much less battery power than before. Bluetooth’s current speed will increase 20-150x from 0.7Mbps-3Mbps to up to 480Mbps over distances of 10 metres, which means that 75MB can be sent in as little as two seconds, a welcome improvement for those used to waiting up to six minutes to complete their transfers.

This capability opens up new possibilities for Bluetooth, allowing far more sophisticated applications to be implemented as early as mid-2007. The Bluetooth SIG’s announcement that it will use the WiMedia/MBOA UWB radio for high-speed Bluetooth suggests that mobile phone companies are already backing UWB.

No More Wires
Of course, the most obvious benefit of UWB is that it is a solution for wireless connectivity. Consumers are tired of wires: they are unsightly and can be difficult to untangle. More to the point, they limit mobility, something which to many seems a little backward in the age of WiFi and Bluetooth, where consumers are getting used to the idea that you can sit wherever you like while sending emails or browsing the Internet.

So it is good news for the industry that the UWB solutions in development will remove the need for data cables in electronic equipment. As well as satisfying consumers, these solutions will stimulate the development of new markets and new applications.

Standards in Progress
The IEEE 802.15.3a standards committee has stalled the UWB standard because current implementations use different incompatible technologies, including a multi-band OFDM technology (MB-UWB) and a direct-sequence technology (DS-UWB). This has held up frequency allocation for UWB outside the US, although ECMA in Germany has proposed frequencies for UWB in specifications that are expected to become international ISO standards next year. This should encourage mass production to bring the cost down to levels that are suitable for the consumer market and for embedding in digital camcorders, video cameras and other portable electronic systems.

The SoC Design Challenge
Power, cost, design size and time to market are key factors for the success of UWB consumer implementations, and many companies will find that they need to enter the system-on-chip (SoC) arena for the very first time.

As far as the SoC design flow is concerned, a key challenge is to integrate the UWB MAC layer with the processor core and other peripherals such as crypto engines or host interfaces, or popular device interfaces. The systems also require high-speed content protection, and while there will be hardware encryption engines, these have to be controlled by a CPU processor. There may also be higher application level features such as pre-and post-processing of video and voice that can make use of the core to save valuable die area.

A well established design flow with the tools to model, simulate, develop and test both hardware and software as concurrently as possible help dramatically in getting the chip to market at the right time with the best performance and at the right cost point.

The flexibility and simplicity of UWB open up the possibilities of integrating short-range wireless connectivity across a broad range of applications. Choice of the most appropriate processor core will in most cases be determined by the needs of the application rather than the UWB MAC. While low-power is a universal need, CPU performance requirements may vary. ARM’s processor roadmap spans the needs of the highest-performance applications, and scales down to satisfy the most cost-sensitive products. Processor cores from ARM are helping many UWB designers achieve a world without wires through simple wireless connectivity.