doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 1 Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: UWB Localization Techniques Date Submitted: 10 August 2004 Source: Benoit Denis Company: CEA/LETI, STMicroelectronics Address: 17 rue des Martyrs, F Grenoble cedex 9, FRANCE (CEA/LETI) 39 ch. du Champ des Filles CH Plan-les-Ouates, SWITZERLAND (STMicroelectronics) Voice:(33)(0) , FAX: (33)(0) , Re: TG4a Ranging Subcommittee Time-of-Arrival Algorithms Abstract:This document describes classical UWB TOA ranging / localization algorithms Purpose:In support of TG4a Ranging Subcommittee work. Notice:This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 2 UWB Localization Techniques Benoît DENIS Fusing Accurate Positioning Capabilities and Digital Communications

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 3 Time Of Arrival (TOA) & Two Way Ranging (TWR) Terminal B Request Prescribed Protocol Delay and/or Processing Time ToTo T Reply T1T1 Terminal A TX/RX Terminal B RX/TX T OF T OF Estimation Terminal A

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 4 Time Of Arrival (TOA) & Two Way Ranging (TWR) Main Limitations / Impact of Clock Drift on Perceived Time Range estimation is affected by : Relative clock drift between A and B Clock accuracy in A and B Prescribed response delay Is the frequency offset relative to the nominal ideal frequency Relaxing constraints on clock accuracy by Performing fine drift estimation/compensation Benefiting from cooperative transactions (estimated clock ratios…) Adjusting protocol durations (time stamp…)

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 5 MAC resources for a double DEV2PNC TWR Transaction T OF Request (Medium Access) T 2 T2T2 PNCs T OF Estimate Acknowledgement Transmitting to DEV PNCs T OF Estimate T OF DEVs T OF Estimate Receiving PNCs T OF Estimate MCTA (Slotted Aloha) T OF PNC DEV Ref DEV Ref PNC T 1 T1T1 Beacon Detection Ex : DEV2PNC Ranging in the Scenario Time stamp (fixed retransmission times T) Beacon synchronization (PNC2DEV) Association procedure in MCTA slots Imm-ACK or Dly-ACK (PNC2DEV) & Association Request (DEV2PNC) DEV-A DEV-C DEV-B PNC Relative clock drift DEV / PNC available Correction of DEVs Time Offset (propagation delay from PNC) PicoNet Synchronization

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 6 Time Of Arrival (TOA) & One Way Ranging (OWR) Terminal A Terminal B Request ToTo Terminal A TX Terminal B RX T OF T OF Estimation Isochronous T1T1 T OF Estimation If Terminals are synchronized to a common clock, direct OWR can be used for Ranging

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 7 DEV-A MAC resources for a single DEV2DEV OWR Transaction Guaranteed Time Slots in the CTA can be used between isochronous DEVs (i.e. with common reference start times) DEV-A DEV-B Ref PNC CTA DEV-C Ref PNC + Ts T AB DEV-Bs Estimate of T AB T CA DEV-As Estimate of T CA Slot 1 Slot 2 Slot 3 T BC DEV-Cs Estimate of T BC Ref PNC + 2Ts Ex : DEV2DEV Ranging in the Scenario DEV-B

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 8 Time Of Arrival (TOA) & One Way Ranging (OWR) Main Limitations / Impact of Synchronization and Clock Drifts on Perceived Time Range estimation is affected by : Clock accuracy Uncertainty on the reference start times (synchronization) Is the frequency offset relative to the nominal ideal frequency Requirements Achieving fine synchronization between terminals prior to ranging

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 9 Mobile (x m,y m ) Anchor 2 (x A2,y A2 ) Anchor 3 (x A3,y A3 ) Anchor 1 (x A1,y A1 ) Positioning from TOA 3 anchors with known positions (at least) are required to retrieve a 2D- position from 3 TOAs Measurements Estimated Position Specific Positioning Algorithms

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 10 Time Difference Of Arrival (TDOA) & One Way Ranging (OWR) ToTo Mobile TX Anchor 1 RX T OF,1 T1T1 Anchor 2 RX T OF,2 T2T2 Anchor 3 RX T OF,3 T3T3 Anchor 1 Anchor 2 Anchor 3 Mobile Isochronous Info T 2 Info T 3 Info T 2 Info T 3 TOA Estimation TDOA Estimation Passive Location TOA Estimation Isochronous

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 11 Mobile (x m,y m ) Anchor 1 (x A1,y A1 ) Anchor 2 (x A2,y A2 ) Anchor 3 (x A3,y A3 ) Positioning from TDOA 3 anchors with known positions (at least) are required to find a 2D-position from a couple of TDOAs Measurements Estimated Position Specific Positioning Algorithms

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 12 Ex. of Possible Embodiment for TDOA/OWR based Systems RF RX & Timing Pulse Processor Serial Data Link + Timing Ref Clock Base Control Unit Short Transmitted Packets + Asynchronous TX Tags = Infrequent Packet Collisions Known Fixed Locations Tag Asynchronous Tags to be localized Tag

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 13 Received Signal Strength Indicator (RSSI) Power Strength could be an alternative solution to TOA/TDOA in the UWB Context Lower requirements in terms of synchronization and clock precision But RSSI requires precise channel behavioral model RSSI is sensitive to channel inconstancy and non-stationarity RSSI does not benefit from UWB high resolution

doc.: IEEE /418r0 Submission August 2004 Benoit Denis, CEA/LETI STMicroelectronicsSlide 14 Angle Of Arrival (AOA) AOA could be an alternative solution to TOA/TDOA in the UWB Context Lower requirements in terms of synchronization and clock precision Two anchors are sufficient for 2D-positioning But UWB Arrays Antennas technology may be not mature AOA requires precise calibration at anchor nodes Cost increases with size and size may not be reduced The number of elements in the array highly depends on the radio environment