Jean-François Hélard

Publications (6)0 Total impact

• Conference Proceeding: Performance analysis of repetition-based decode-and-forward relaying over asymmetric fading channels.

  Sudhan Majhi, Youssef Nasser, Jean-François Hélard, Maryline Hélard
  Proceedings of the IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2010, 26-29 September 2010, Istanbul, Turkey; 01/2010
• Source

  Available from: scirp.org

  Conference Proceeding: Power Spectral Analysis of Orthogonal Pulse-Based TH-UWB Signals.

  Sudhan Majhi, A. S. Madhukumar, Youssef Nasser, Jean-François Hélard
  Proceedings of the 71st IEEE Vehicular Technology Conference, VTC Spring 2010, 16-19 May 2010, Taipei, Taiwan; 01/2010
• Source

  Available from: archives-ouvertes.fr

  Conference Proceeding: Iterative Channel Estimation for Orthogonal STBC MC-CDMA Systems over Realistic High-Mobility MIMO Channels

  Fabrice Portier, Stephan Sand, Jean-François Hélard
  [show abstract] [hide abstract]
  ABSTRACT: This paper considers a downlink multiple-input multiple-output (MIMO) multi-carrier code division multiple access (MC-CDMA) system with pilot aided channel estimation (PACE) and iterative channel estimation (ICE) in the receiver. Exploiting orthogonal space-time block coding (STBC), we investigate ICE schemes as a simple extension of PACE using estimated data chips as additional pilots. Due to the superposition of different users' spread data signals, zero-valued chips can occur after spreading, which can cause noise enhancement when using data estimates as reference signals in ICE. Hence, we propose MIMO channel estimation methods to overcome the above problem. Simulations with a realistic outdoor MIMO channel model, over a wide range of data rates and speeds, show that ICE can outperform PACE at the cost of increased complexity
  17th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC’06); 10/2006
• Article: Performance comparison of multi-user detectors for the downlink of a broadband MC-CDMA system

  Fabrice Portier, Rodolphe Legouable, L. Maret, F. Bauer, N. Neda, Jean-François Hélard, E. Hemming, M. Des Noes, Maryline Hélard
  CoRR. 01/2006; abs/cs/0606117.
• Article: Multicarrier CDMA techniques for future wideband wireless networks.

  Maryline Hélard, Rodolphe Legouable, Jean-François Hélard, Jean-Yves Baudais
  Annales des Télécommunications. 01/2001; 56:260-274.
• Source

  Available from: archives-ouvertes.fr

  Conference Proceeding: Channel Estimation for Orthogonal STBC MC-CDMA Systems over Realistic MIMO Channels

  Stephan Sand, Fabrice Portier, Jean-François Hélard
  [show abstract] [hide abstract]
  ABSTRACT: This paper investigates a downlink multiple-input multiple-output (MIMO) multi-carrier code division multiple access (MC-CDMA) system with pilot aided channel estimation (PACE) and iterative channel estimation (ICE) in the receiver. Due to the superposition of different users’ spread data signals, zero-valued chips can occur after spreading, which can cause noise enhancement when using data estimates as reference signals in ICE. Hence, we propose a MIMO channel estimation method to overcome the above problem and avoid noise enhancement in ICE. Simulations results for PACE and ICE were computed for a realistic outdoor MIMO channel model.
  15th IST Mobile & Wireless Communication Summit;