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NAVIGATION & GEOLOCATION Fig. 2: UWB time based. It is possible to extend the tracking scheme previously discussed and let the mobile device retrieve the location information from the system. This is, however, rather cumbersome and bandwidth inefficient. The latency incurred may be too large to meet the requirement for real-time navigation. Additionally, the privacy may also be a concern in such an implementation since the mobile device location information is available to the system. The best option in this case is to use the beacons in broadcast mode and have the tag do the positioning computation. Once again, the clocks from the beacons are synchronized so the tag can apply exactly the same algorithms described above and determine its position. This approach is similar to GPS, where the infrastructure network acts like the satellites and mobile devices like GPS receivers. Since the mobile node does not need to transmit at all, there are two significant benefits of such an implementation: the mobile location is kept at the node and therefore guarantee of complete privacy; the mobile nodes do not take up any bandwidth and therefore there can be a very large number of devices operating in the navigation mode in a network. Hardware and software requirements At first glance, a UWB-based RTLS system might appear to be very complex, requiring high computation and thus not really cost effective. However, a close look at the hardware and software requirement will show that such a system can actually be more cost-effective than existing products. On the hardware side, thanks to the latest advances from the semiconductor industry, there are single chip CMOS solutions available on the market. A complete radio device can be built in a compact form factor using the IR-UWB radio chip. Taking advantage of power efficient protocols and positioning algorithms, a radio node can be capable of operating for more than 3 years in tracking mode and more than 48 hours in navigation mode. There are significant developments on the software side. Efficient stacks and location algorithms have been developed to allow excellent power efficiency and bandwidth efficiency. The radio node can have a low cost, low power MCU that is powerful enough to run the complete stack and positioning engine all at once. Abundant software is already available for indoor mapping, route planning and navigation on both desktop and smartphone/tablet and can be easily harvested for UWBbased applications. What’s next? Highly accurate and highly reliable indoor positioning is now a reality thanks to IR-UWB. Enterprise applications such as healthcare, factory automation, and warehousing are already leveraging this technology to track goods, tools, staff and increase their productivity. Fig. 3: Multi-lateration based on time difference of arrival. Car manufacturers are also integrating this technology to offer secure passive entry systems by measuring the real distance between the key and the car avoiding relay attack. Consumers will benefit from this technology in the near future. The number of applications enabled by a sub-10cm positioning is endless: from carts that will guide them directly to a product on a shelf to intelligent homes capable of controlling light, HVAC and alarm based on the user’s exact position. Exactly as GPS has become so important in our daily life and has been integrated into the mobile phone to offer outdoor navigation, the integration of IR-UWB technology will allow anyone to seamlessly navigate outdoors and indoors with a high level of accuracy. 26 Electronic Engineering Times Europe July/August 2014 www.electronics-eetimes.com


EETE JULAUG 2014
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