Precise Cooperative Positioning of Low-cost Mobiles in an Urban Environment

PhD Offer


Due to the wide inclusion of GNSS receivers in mobile phones and cars, the user has now constant access to information on his/her geographic location. However, the accuracy and integrity of the computed position generally needs to be improved, especially in an urban environment where GNSS signal reception conditions are degraded. A hybridization with signals from other internal platform sensors such as accelerometers, gyroscopes, magnetometer or even WiFi signals could improve the positioning quality. However, recent research activities have shown that even with hybridization it was still extremely challenging to consistently reach sub-meter positioning in almost every environment as required by a growing number of applications. As a consequence, RTK precise positioning has been investigated for low-cost phone users in an urban environment, especially since Google announced that its mobile platforms will allow access to its raw GNSS measurements. As of today, one limitation to using RTK positioning techniques is the lack of a dense enough reference station network.

This PhD proposes to research how a connected user community can help itself in order to obtain more precise positioning data through the exchange of information such as measurements, locations, etc., therefore considering each member of the community as a potential reference station.


The goal of this thesis is to enable the precise positioning of low-cost mobile phones in urban, pedestrian or vehicular environments, using a cooperative exchange of information linked to positioning.

In detail, this will involve the aiding of a mobile phone (referred to as M), using its own measurements/information for positioning purpose, with those of neighboring mobile phones (referred to as X) so that mobile M can compute a more precise position. For example, information on the position/quality of the position/measurements/quality of the measurements of several mobile phones X in the vicinity of mobile phone M (restricted by its location, supply of relative multi-user positioning, environmental understanding, measurement comparison, etc.) would have an added value.

This situation could be interpreted as a desire of community localization between a group of users, each adding their measurements/information and each considered being considered as a potential reference station by the other users.

Research Work

  • Phase 1: State-of-the-art on
    • GNSS systems
    • GNSS measurement model, Position computation and quality assessment
    • GNSS precise positioning techniques
    • Understanding of disturbances affecting GNSS positioning in urban environment
    • Other navigation sensors available in a low-cost mobile and modelling of their measurements
    • Hybridization techniques
    • Cooperative positioning
  • Phase 2: Mathematical modelling of the mobile measurements/information and of the cooperative positioning filter
    • Mathematical derivation of the cooperative positioning filter assuming a high number of connected users and several types of measurements/information
    • Mathematical modelling of the measurements/information available
      • To do so, data will be collected in a representative environment
  • Phase 3: Development of a software simulator and proof-of-concept
    • Definition of a representative scenario (distribution of users in an urban environment)
    • Development of the software tool
    • Testing to show the performance of the proposed collaborative positioning compared to standalone positioning based on a chosen set of parameters
  • Phase 4: Real condition testing
    • Definition of test scenario
    • Data collection
    • Comparison with simulator results
  • Phase 5: Optimization of the concept via measurement/information selection
    • Definition of measurement selection criteria (C/N0, satellite elevation, etc…)
    • Assessment of the improvement based on the proposed criteria
  • Phase 6: PhD manuscript writing


  • F. Berefelt, B. Boberg, J. Nygårds, P. Strömbäck, S.-L. Wirkander, “Collaborative GPS/INS Navigation in Urban Environment”, Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 1114-1125.
  • L. Deambrogio, C. Palestini, F. Bastia, G. Gabelli, G. E. Corazza, J. Samson, “Impact of high-end receivers in a peer-to-peer cooperative localization system”, Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS), 2010, Kirkkonummi, 2010, pp. 1-7, available:…, last accessed 10/10/2016.
  • Roberto Garello, Letizia Lo Presti, Giovanni E. Corazza, Jaron Samson, “Peer-to-Peer Cooperative Positioning, Part I: GNSS-Aided Acquisition”, Inside GNSS, March/April 2012, Volume 7 Number 2, pp. 55-63, available:
  • Roberto Garello, Jaron Samson, Maurizio A. Spirito, Henk Wymeersch, “Peer-to-Peer Cooperative Positioning, Part II: Hybrid Devices with GNSS & Terrestrial Ranging Capability”, Inside GNSS, July/August 2012, Volume 7 Number 4, pp. 56-64, available:
  • Huang Bin, Yao Zheng, Cui Xiaowei, Lu Mingquan, Guo Jing, “GNSS Collaborative Positioning and Performance Analysis”, Proceedings of the 27th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 1920-1930.
  • Matthew J. Murrian, Collin W. Gonzalez, Todd E. Humphreys, Kenneth M. Pesyna Jr., Daniel P. Shepard, Andrew J. Kerns, “Low-cost precise positioning for automated vehicles”, GPS World, August 28, 2016, last accessed 10/10/2016, available:

Candidate Profile

Masters in Telecommunications (signal processing) or Mathematics

Other information

Host institution: TeSA
PhD supervisor: Julien Olivier (
CNES Coordinator: MARMET François-Xavier
In order to apply for this PhD offer, Please fill in the online form on the CNES website before the 31st of March 2018.