ETH - Indoor Positioning & Indoor Navigation


13:15 - 13:45	Fabrizio Tappero, Bertrand Merminod, Marc Ciurana (presenting author, at CTAE Aerospace Research & Technology Centre): IEEE 802.11 Ranging and Multi-lateration for a Software-defined Positioning Receiver The implementation of a ranging exploitation method over the IEEE 802.11 signal standard for a software-defined radio architecture is presented. We propose the current wireless local access network (WLAN) as standard assistive infrastructure for ubiquitous localisation and positioning. The paper describes the architecture of a localisation receiver built around a FPGA. The described receiver can process GNSS signals, available for any number of satellites, together with IEEE 802.11 signals available from surrounding access points to infer its own position. The single ranging method, the hybrid GPS and IEEE 802.11 multi-lateration positioning calculation method and their implementation in a single software-defined receiver are discussed.

13:45 - 14:15	Javier Prieto (presenting author at CIT, University of Valladolid), Santiago Mazuelas, Alfonso Bahillo, Patricia Fernández, Rubén M. Lorenzo, Evaristo J. Abril: On the Minimization of Different Sources of Error for an RTT-Based Indoor Localization System without any Calibration Stage Prior to the trilateration process, different sources of error disturb the range estimates in any localization system, especially in dense cluttered environments where the non-line-of-sight (NLOS) between the mobile user and the access points becomes the main problem. Common error mitigation approaches are based on linear or Gaussian assumptions that are not fulfilled in this kind of scenarios, such as indoor or dense urban outdoor areas. This paper points out the better performance of a round-trip time (RTT)-based localization system when combining a prior NLOS measurements correction method with particle RTT-only tracking, since hard decisions are only made in the last stage of the positioning process, and neither linear nor Gaussian models are assumed. The final performance leads to a reduction of more than 50% of the error obtained without any mitigation technique, keeping the requirement of no calibration stage.

14:15 - 14:45	Zemene W. Mekonnen (presenting author, at ETH Zurich), Christoph Steiner, Heinrich Lueken, Armin Wittneben: Maximum Likelihood 3-D Positioning with a Priori Knowledge of Nodes Topology for UWB Based Human Motion Tracking In this paper we analyze an ultra-wideband (UWB) based wearable human motion tracking system. A maximum likelihood (ML) estimator, which incorporates the UWB distance measurements and the a priori knowledge of nodes topology to localize a node, is presented. The result of measurement campaigns is compared with computer simulation results to evaluate the performance of the proposed scheme. Based on this performance evaluation, it is shown that taking into account a priori knowledge given by the topology of the nodes can improve localization accuracy in harsh environments (i.e. in the case of multipath propagation and when enough number of line-of-sight (LOS) distance measurements are not available to perform lateration). Moreover, it reduces the required number of anchors to localize a node.

14:45 - 15:00	Andreas Eidloth (presenting author, at Fraunhofer ISS), Jörn Thielecke: A Mathematical Model for a Polarisation Based Orientation Measurement Principle in Time of Arrival Radio Localisation Systems Determination of orientation in time of arrival radio localisation systems is the aim of this work. This goal should be achieved only by using carrier phase measurements. Therefore, a special antenna configuration is necessary. The transmitter, which orientation shall be ascertained here, is equipped with a linearly polarised antenna. Two opposed circularly polarised antennas are used at a receiver. A generic mathematical model for this setup will be presented here. The electromagnetic field theory will be deployed for the complete transmission chain up to the point where carrier phase measurements are obtained. The transmitter and receiver antennas can be translated and rotated freely within three-dimensional space. The suggested model can be used in simulation environments to synthesise localisation measurement data. With this approach, the behaviour of carrier phase measurements due to rotation and translation of the user equipment can be modelled.

Oral Presentations (Poster Teasers)

Thursday, September 16
Auditorium G7

15:00 - 15:02	Marc Ciurana (presenting author), Domenico Giustiniano, Albert Neira, Francisco Barcelo-Arroyo, Israel Martin-Escalona: Performance stability of software TOA-based ranging in WLAN (Poster Teaser) TOA-based ranging with off-the-shelf WLAN equipment can enable cost-effective and advanced accurate positioning. Authors reported first results from a software-only ranging technique that employed the CPU clock of the client WLAN device to perform round-trip-time measurements. The transmission and reception of IEEE 802.11 frames was time-stamped at OS level through the driver of the client’s WLAN interface. Although maximum reached accuracy was better than in previous software proposals, the time variability of the WLAN interruption handling by the OS caused stability degradation. The current contribution proposes several enhancements to palliate this critical negative effect on the initial proposal and shows the importance of the client OS configuration when addressing it. To this end the performance of the enhanced method adopting different OS configurations is comparatively evaluated. The current research intends to improve the robustness of this location technology in order to bring it closer to the market.

15:02 - 15:04	Daniel Froß (presenting author at TU Chemnitz), Jan Langer, André Froß, Marko Rößler, Ulrich Heinkel: Hardware Implementation of a Particle Filter for Location Estimation (Poster Teaser) In this paper we present the hardware implementation of a particle filter for location estimation. Based on distance information to static network nodes, the filter estimates the three-dimensional position of a mobile network node. The design has been derived from a set of formal operation properties and synthesized for an FPGA prototype platform. Accessed through a serial interface, it can be used as a location estimation core from microcontrollers with low computational power. The implemented models for state transition and measurements can be re-parameterized during operation. Due to the chosen design approach these models can also easily be modified or exchanged in order to match the application needs. The correct functionality of the implementation has been shown using real time-of-flight based distance measurements. Therefore, the prototype platform has been integrated in an existing IEEE 802.15.4a compliant wireless network infrastructure.

Session Chair: Dr. Anna Maria Vegni, University of Roma Tre

TOF TDOA, Part 2

15:30 - 16:00	Khalid Nur (presenting author, at Imperial College London), Shaojun Feng, Cong Ling and Washington Ochieng: High Accuracy WLAN Positioning using Sparse Estimation Techniques This paper develops a high positioning accuracy function for indoor mobile devices based on WLAN. It proposes a time estimation technique that addresses the system bandwidth and multipath limitations and achieves sub-metre ranging under typical propagation scenarios. The proposed technique is based on sparse estimation which is enabled by an adapted model for the received signal and the use of a high sampling rate. It provides lower complexity and faster extraction of measurements compared to existing high resolution time estimation techniques without compromising the achieved accuracy. In order to reduce the effect on the data throughput and minimise user interaction, the extraction of measurements is based on exploiting the data frame preamble. The ability of sparse estimation techniques to support the required ranging accuracy with low processing power and under operational scenarios has been demonstrated by simulation. The development of a prototype platform is underway.

16:00 - 16:30	Dohyung Park (presenting author, at Samsung Advanced Institute of Technology (SAIT)), Joonsung Kang, Eung Sun Kim: Ad hoc Indoor Peer-to-peer Tracking using Relative Location Estimation Finding and tracking a target device for a user device in indoor environments can be utilized in many kinds of applications. Instead of absolute location which requires maps and absolute location of the reference points, We consider relative location, which is sufficient to help the user move to the target. Since it is difficult to measure the signal direction, we use distance measurement to estimate the relative direction of the target. If the user device is moving, the approach can estimate the relative direction of the target with reference to the moving direction. This approach is appropriate to the ad hoc indoor localization system since the system is fully ad hoc peer-to-peer tracking. That is, in the proposed system, the user device can finds the relative location of the target without any prerequisite knowledge.

16:30 - 16:45	Jiyun Shen (presenting author) and Yasuhiro Oda (at NTT DOCOMO): Direction Estimation for Cellular Enhanced Cell-ID Positioning Using Multiple Sector Observations In this paper, we propose a method that improves the accuracy of the direction of User Equipment (UE) for Enhanced Cell-ID (ECID) positioning of mobile phones. The proposed method estimates the direction of UE by the use of different reception sectors. The evaluation of the direction accuracy and positioning accuracy are presented via computer simulations. The improvement in the direction accuracy is approximately 65% for the Rayleigh fading environment under the assumption that the number of observations is 10 and the width of the sector is 60°. The RTT (Round Trip Time) positioning accuracy is improved by about 50% using the proposed method when the RTT measurement error is 156 m and the cell spacing is 4 km.

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