007_EETE

EETE MAY 2013

Impulse-radio ultra-wide band IC takes the lead on accurate geo-positioning By Julien Happich fabless semiconductor company BeSpoon and CEA-Leti have just demonstrated an Impulse radio ultrawide band (IR-UWB) integrated circuit able to measure distances within a few centimetres of accuracy. During their experiments with early prototypes, the companies have established what they claim to be a world-record operating range at 880m when following IR-UWB’s standard regulation and 3,641m in compliance with the regulation for emergency situations. The chip jointly designed by BeSpoon and Leti features a full IR-UWB CMOS-integrated transceiver that is BeSpoon’s first IR-UWB chips. able to perform accurate distance measurements. The standalone chip (RF front-end and digital base band) was designed to be “smartphones-friendly” in the sense that it could leverage the components already available on most smartphones to become operational, allowing OEMs to design-in the new capability for only the cost of the new chip. CEA-Leti had worked on UWB for the past 12 years, initiating its first research program on the topic in 2000. It is only after a decade of explorations and dead-end pruning that some results became commercially exploitable, explained Pierre-Damien Berger, a researcher at CEA Leti. This is when Jean-Marie André, now BeSpoon’s CEO, got convinced that the technology could yield new functionalities and new services around very accurate geolocation. It took another three years of investigations under a joint research program established with CEA-Leti for BeSpoon to cover the gap between its initial proof of concept and product industrialisation. “From the very beginning, there were several companies interested in this technology, but few had the expertise to cover the last mile, from academic results to a real product” explained Jean-Marie André. “Now we have several big names among our strategic partners, large system integrators who are currently exploring different use cases and who would be our first customers if we can supply them the chips in volume.” Several wafers were produced at CEA-Leti and André expects the IC to ramp up in volume production in “several quarters”, probably early next year, to be produced using STMicro’s foundry services. “Today, about 95% of indoor positioning solutions rely on WiFi signal strength which varies a lot, hence the fairly low accuracy within a meter at best if you don’t move too much” jokingly commented André. “So far, all commercial IR-UWB solutions were based on discrete components assembled on a PCB. These were not cost-constrained applications and tuning the timing for synchronisation and signal modulation could be done by changing a few capacitor values until the solution worked for the intended application”, explained André, “whereas integrating everything into a single chip was the real challenge, and very few labs in the world are able to do that. We are aiming at consumer volumes and our chip is extremely optimised and price constrained”. Combining a UWB radio receiver and transmitter with signal drivers and a precise timer for synchronisation and modulation, each chip is able to track various signal paths and find out which one is the earliest to arrive (with the shortest distance travelled A geofencing tag that could be used for keeping personal assets within user-defined distances. being the line-of-sight) based on precise timeof flight measurements. Because radio waves travel at the speed of light, a 1ns time delay represents 30cm of travelled distance. “Designing a circuit able to provide accurate timing to within a few hundred picoseconds was extremely challenging” emphasized André, “the actual chip has a proven timing accuracy below 120 picoseconds, which translates into a positioning accuracy of under 5cm.” This precision is not affected by walls or people passing by, offering a very robust solution to indoor location. In one use-case, BeSpoon thinks the chip could be used for mobile geofencing, whereby user-defined tracking distances could be set between a mobile phone or a portable belt-tag and other electronic devices (for example a laptop, a cashier’s desk to be unlogged, car keys). The belt-tag or the smartphone could then alert the user in case these belongings were left too far behind. For precise indoor geolocation, existing WiFi hotspots which are currently used for positioning via signal strength triangulation could be upgraded with a USB dongle bearing BeSpoon’s IRUWB chip. Jean-Marie André feels BeSpoon could have a future as exciting as that of companies who pioneered Bluetooth and WiFi. At first, the IR-UWB chip could be used in combination with other RF technologies. In a later stage of adoption, it may end-up being integrated with other compatible RF blocks into radio modules or even licensed as an IP block for chip integration. Deducing the time of flight of the signal between two transceiver chips. 6 Electronic Engineering Times Europe May 2013 www.electronics-eetimes.com


EETE MAY 2013
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