A 6 to 7 GHz front end for UWB based radio positioning Alessio De Angelis, Satyam Dwivedi, Peter Händel

Outline Introduction -application scenario -project overview In-house development of UWB test bed Development of an UWB pulse front end Conclusions Satyam Dwivedi - KTH Signal Processing Lab /10/04

Introduction: scenario Satyam Dwivedi - KTH Signal Processing Lab /10/04

Embedded sensor fusion for personnel localization Flexible platform: -Integration of: GPS, radio, INS, camera- based, magnetometer sensors -development of sensor fusion methods -Data streaming to Command and Control station VINNOVA-DST Indo-Swedish project on Embedded Systems. Satyam Dwivedi - KTH Signal Processing Lab /10/04

A. De Angelis, J. O. Nilsson, I. Skog, P. Händel, and P. Carbone, “Indoor positioning by ultrawide band radio aided inertial navigation,” Metrology and Measurement Systems, vol. XVII, pp. 447–460, In-house UWB test-bed Pulse-based UWB (low complexity – power – cost) Fine time resolution Accuracy (10 cm - order) Robustness to multipath (resolvable paths) Round-Trip-Time measurement (no pulse-synchronization) Satyam Dwivedi - KTH Signal Processing Lab /10/04

Round-Trip-Time ranging Variant of TOA – ”2 way” time-of-flight Master-slave architecture (measurement unit - responder) Advantage: Synchronization requirement can be relaxed Potentially infrastructure-free (anchor-less cooperative positioning) Drawback: Compensation for slave latency TX/RX in both master and slave

UWB research issues (ongoing work): Interference mitigation (energy detection RX) Flexible platform for digital signal processing (FPGA) High frequency radio front-end Fundamental limits for position estimation (theoretical evaluation) Experimental characterization (test environment) Sensor fusion Satyam Dwivedi - KTH Signal Processing Lab /10/04

UWB test environment Reactor hall R1 -12 x 25 x 12 m -controlled level of RF interference Ubisense ® positioning system -TDOA / AOA of UWB pulses -8 wired sensors (synchronization) -3D visualization tool Satyam Dwivedi - KTH Signal Processing Lab /10/04 Courtsey: Janne Danielsson

6.5 GHz front end architecture Satyam Dwivedi - KTH Signal Processing Lab /10/04 UWB Pulse generator LNA IF AMP BPF IF LO RF LO RFIF TX RX 6.5 GHz Energy Detector HPF Baseband UWB pulses in the MHz band (step-recovery diode) Benefits of using the 6-7 GHz band : smaller antenna size less interference from other narrowband users: better regulation of the threshold of the energy detector potentially longer operational range higher robustness.

Experimental setup Satyam Dwivedi - KTH Signal Processing Lab /10/04

Experimental results (1 of 2) Goal: to acquire low duty-cycle pulses (pulse repetition frequency: 16 kHz) 13 GHz spectrum analyzer, Rohde & Schwartz 10 MHz resolution bandwidth max-hold setting Satyam Dwivedi - KTH Signal Processing Lab /10/04 Interference spectrumSpectrum of the TX mixer output, upconverted UWB pulse, 6.5 GHz carrier.

Experimental results (2 of 2) Spectrum of the energy detector input at the receiver, downconverted pulse. Satyam Dwivedi - KTH Signal Processing Lab /10/04 Time-domain acquisition of the energy detector output (antennas connected), average over 16 acquisitions. 200 MHz, 1GSa/s Digital oscilloscope

Future work Interfacing with existing baseband UWB test bed Interfacing with FPGA (Virtex5 XUPV5 dev. board) -timing and control logic (currently: logic and delay lines ICs) -High-speed DSP methods implementation -Flexibility -Re-configurability Testing various localization techniques Satyam Dwivedi - KTH Signal Processing Lab /10/04

Conclusions Overview of broader context of this research activity: -“Embedded sensor fusion for personnel localization” project In-house development of UWB positioning test bed: -Positioning approach, research issues Development of an 6 to 7 GHz UWB pulse front end -Motivation: smaller antenna size, less interference (improved range) -Experimental results -Future work Satyam Dwivedi - KTH Signal Processing Lab /10/04