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| Spring 2005 | Frontpage | Subscribe | Feedback | ||
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Wireless USB: The Scoop Is Bluetooth about to get killed? Wireless USB (WUSB) Promoter Group is set to roll out its new short-range wireless technology and have products on shelves within the year. Already, promoters are forecasting that WUSB will quickly takeover the Wireless Personal Area Network (WPAN) market currently lead by Bluetooth and joined by the emerging ZigBee standard. With hype coming from all sides, product developers need to figure out what's best for them. The purpose of this article is to provide a short summary of events in the industry and how, why and where Wireless USB might beat out other technologies in the market. Apple recently announced that its new line of Powerbook G4 notebook computers will utilize the new and improved Bluetooth 2.0 w/ Enhanced Data-Rate (EDR) wireless interface. Much like USB 2.0, the new Bluetooth will be backward compatible with older devices and promises to boost data rates from a theoretical maximum of 1Mbps to 3Mbps. But Apple's Bluetooth 2.0 support will only be of use if device manufacturers also adopt the technology and Apple is currently taking heat for what may be a premature adoption of the new standard. Apple, however, was also an early adopter of USB, at the time under criticism, so the company has a proven record of recognizing successful technologies in their early stages. The current endorsement of WUSB bears a striking resemblance to the early days of Bluetooth when its Special Interest Group (SIG) was heralding Wireless Personal Area Networks as a revolution in interconnectivity among consumer and enterprise peripherals. Nevertheless, the two technologies have some fundamental differences. Wireless USB uses the same "host and device" topology as wired USB. Each network cluster has one host (master device) and up to 127 device peripherals (slaves). In the absence of a host, devices cannot communicate with one another, but many applications require precisely this type of "peer-to-peer" communication. To get around the problem, wireless USB will utilize "dual-role" devices that offer limited host as well as device capabilities. It is not yet known how much the dual-role capability will cost per-unit. Bluetooth also uses a master-slave system, but each Bluetooth device inherently functions as either master or slave, thus offering full peer-to-peer connectivity at no extra charge. Despite this drawback, WUSB is promising a better solution on two platforms - interconnectivity and speed. Unlike Bluetooth, which today still suffers from compatibility problems, USB has thoroughly penetrated the market as the interface of choice for most applications and will likely take advantage of strong brand recognition when it hits the market. Starting with a simple dongle, Wireless USB will allow existing USB ports to interface to a wide range of new Wireless USB enabled devices scheduled to hit the market later this year. Most importantly, Wireless USB promises to boost raw data rates to 480Mbps, two orders of magnitude above Bluetooth 2.0 w/ EDR and fast enough to stream multi-channel audio/video and connect computers to external disk drives etc. To do this, Wireless USB will be built around the new Ultra-Wide Band (UWB) technology, also in its early stages. UWB is set to make use of a recently legalized frequency spectrum from 3.1GHz to 10.6GHz, allowing each channel a bandwidth of around 500MHz. The FCC restriction governing this unconventionally wide band is extremely low output power. Thus, UWB aims to provide high transfer rates with inherently low power consumption. The cost of this performance is very short range - less than 10m; 3m for maximum transfer rate. By comparison, Bluetooth's range can extend to 100m. Promoters, however, are billing UWB's limited range as an added security measure and as a way to allow multiple device clusters within the space of a home/office. The concept is that the WUSB nets will be too short-range to interfere with one another. 2.4GHz networks (Bluetooth, 802.11b, 802.11g, ZigBee) are below UWB's spectrum. Only 802.11a networks operating nearby and transmitting at 5GHz may cause conflicts. As far as security goes, having a limited range is not enough. The same physical laws that make a high-gain antennae an effective transmitter also make such an antennae a powerful receiver. There is still, therefore, potential for unauthorized access by snooping receivers located outside the expected range of the network. Verification between device and host must be securely administered and those required encryption schemes will add overhead and reduce effective data rates. To some extent it looks like Bluetooth and Wireless USB will go head-to-head and we'll see who the survivor is in a couple of years. But there is also a chance for the technologies to coexist - Bluetooth may be the better peer-to-peer solution whilst Wireless USB could become the standard for self-powered, high-speed peripherals currently using wired USB. More expensive devices like high-end cell phones, PDAs and notebook computers may offer both interfaces. In the next issue we'll discuss ZigBee and how it could also have a profound influence on the future of wireless. Stay tuned. 
For more info on Wireless USB in your design, contact Nuvation. Customer service · To subscribe yourself or a friend, please click here. · Questions? Comments? Send us your feedback. |
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