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Focusing antennas for a green 5G. A project awarded with the “Economic Impact” prize by the French Research Agency

TRIMARAN: it is a collaborative research project for green future mobile networks! It just received the award of “Economic Impact” at the Event organised by the French Research Agency called Rencontres du Numérique de l’Agence Nationale de la Recherche 2016.

The project in short

In the 2020’s, the 5th generation (5G) of mobile networks will connect several dozens of billions of objects with an unprecedented diversity: factories, cars, glasses, surgery tools, etc… This mass risks to generate a colossal energy consumption. However, the Next Generation Mobile Network alliance (NGMN) has declared that «5G should support a 1,000 times traffic increase in the next 10 years timeframe, with an energy consumption by the whole network of only half that typically consumed by today’s networks».

Some revolutionary and energy saving transmission techniques are based on “focusing antennas”. However, some technological challenges limited their applicability to Smartphones in low mobility. As soon as 2010, researchers in Orange sense the potential of these technologies for the future 5G and gather the partners of the consortium of TRIMARAN to meet together the challenges and produce together major innovations:

  1. The partners of the project hold in total more than 20 patents on focusing by Time Reversal and on miniature antennas (Orange 14, ATOS 4, Langevin Institute 4 et INSA-Rennes 3)
  2. 5 years later, focusing is now extensible to vehicles (high speed train included), low cost and small objects, secured communications, guidance etc …
  3. The innovation for connected vehicles has been recognised as Most Promising Technical Approach for 5G in the flagship European Project on 5G called METIS
  4. The new French research project SpatialModulation is pursuing the innovation on small objects
  5. The promotion of innovations continues via Horizon 2020 European projects from the 5G-PPP and through 3GPP

Finally, the prototype of focusing antennas based on Time Reversal produced by the project has been reported in press articles and has been demoed in four congresses, among which, the largest industrial event in this area: the Mobile World Congress 2016.

The partners of the TRIMARAN project

  • orange         Coordinator
  • InstitutLangevinCNRSESPCI
  • TelecomBretagne
  • Thales
  • Time Reversal Communications, from Atos group

The dates

  • Start: Janvier 2011.
  • Duration: 39.5 months (36 months + extension)

Funding and supporters

TRIMARANwas funded by  ANR and supported by ImageReseauxSystematic Under the technical name: Time-Reversal MIMO OFDM Green communicAtions based on MicRo-structured Antennas

Demos (some with Luxondes screen) and articles for the general public:

The story of TRIMARAN in 3 chapters

Chapter I: Before 2010, researchers in Orange study Time Reversal focusing of electromagnetic waves and identify it as a green technology.

They observe the following experiment.

During a learning phase, illustrated below, a first antenna (for instance the one in a smartphone) emits a “ping” in a room, this ping is reverberated by walls and obstacles. Another antenna (for instance an antenna of the network, composed of four intelligent and coordinated elements) stores the received pings as well as its echoes, in a synchronous manner, over its four elements.


Then, during a second focusing phase, the antenna of the network emits the previously stored ping and its echoes, but time reversely. Researchers observe a signal which is focused in time and space. This is the Time Reversal space-time focusing discovered by Prof. M. Fink and its team at the Laboratoire Onde et Acoustique in the 1980’s for sound and ultrasound.

These first works (illustrated below) are published in ‘Investigation of space-time focusing of time reversal using FDTD’, in Proc. IEEE MTT-S International Microwave Symposium digest.  June 2009, par Hanae TERCHOUNE, David LAUTRU, Azeddine GATI, Man Faï WONG, Joe WIART and Victor FOUAD HANNA.


Watch waves move:

  1. Click here to watch how the “ping” emitted by the device propagates in the room and is reverberated.
  2. Click here to watch ideal time reversal (i.e. if we could cover walls with sensors storing the ping and its echoes, and if these sensors could later re-emit what they had previously received, in reverse order).
  3. Click here to watch time reversal in practice (i.e., with only four sensors storing the ping and its echoes, and replaying them in reverse order).

As illustrated below, focusing seems to be a promising technology to reduce the required transmission power to deliver a same data rate to a user. By bringing the energy where it is necessary, the network can save energy.


Chapter II: In 2010, researchers in Orange gather the partners of the TRIMARAN project to work together on green future mobile networks. The French Research Agency selects and funds the project, which starts in january 2011. 

The partners are all experts of Time Reversal focusing, miniature antennas or signal processing for Wireless communications. Prof. M. Fink is one of the founders of the Langevin Institute.

The Langevin Institute and ATOS together design miniature antennas for objects (on the left hand side below) with multiple ports. Orange, Télécom Bretagne and Thalès together, compare these antennas to small state-of-the-art antennas (in the middle below) and show that they are more robust to random positions thanks to channel propagation measurements  made in a test appartment  at Orange Labs Belfort (on the right hand side below) and thanks to simulations.


In parrallel, INSA-Rennes rapidly develops two platforms of Time Reversal focusing, that can monitor any antenna (with several ports), either the conventional antenna or the new miniature antenna both produced by the project. Data is transmitted and thanks to an oscilloscope, it is shown that the signal at the center of the focused spot is strong and “neat” (weak amount of echoes), whereas the signal outside the focused spot is weak and “scrambled” (with multiple echoes).


Together, Orange, INSA-Rennes and Thalès innovate in signal processing and show that focusing (in addition to be useful to save energy) can cover a larger diversity of services to be offered by future mobile networks.

On the one hand, they show that Time Reversal enables to reduce the complexity at the receiver, by delivering a signal which is near (i.e. nearly without any echoe) in certain conditions (at low signal to noise ratio) and with a sufficient number of radiating elements in the antenna at the network side (typically 16).  Based on simulations, it is shown that it is even more true when the number of antenna elements is very high. Experimentally, they transmit 240 Mbits/s using a bandwidth of 30MHz, 256 QAM, and a dumb receiver which can only work in an echoe-free environment.

=> To connect small objects in high data rate with a green focusing technique, is possible.



On the other hand, they propose a solution to focus towards a fast moving vehicle. This innovation has later been improved by Orange with Uppsala University and Chalmers University of Technology. The figure below illustrates the quality of service that would be obtained in urban environment, if the network tried to focus towards cars (blue corresponds to a nice quality, red to a bad quality). Because of the delay between learning and focusing, the network misses the target … especially out of traffic jams.








Click here to see the animated version!

The figure below illustrates the quality of service that would be attained, if the network tried to focus towards cars, using TRIMARAN project’s innovation. One can observe a considerable improvement.


Click here to see the animated version!

The figure below shows the quality of service which would be attained using the innovation of TRIMARAN later improved during the METIS 2020 project. This is perfect.


Click here pour voir la version animée.

=> Connect vehicles in high data rate with a green focusing technique, this is possible.

Numerous other innovations (see publications) are proposed to cover the diversity of services and applications for 5G.

Chapter III: starting in 2012, via European projects, TRIMARAN disseminates and improves its innovations so that the future 5G be green even when it has to serve connected vehicles and small low cost objects.

In parallel, starting in 2012, Europe funds Research on 5G. Its flagship project is called METIS 2020 and gathers almost all the industry (27 partners from industry and academia). One candidate technique for 5G, called massive multiple-input multiple-output (MIMO), with 64, 128 or even 256 radiating elements per antenna is studied to deliver higher data rate, save energy, and connect … smartphones in low mobility. This same concept is studied at a Global level, by the consortium of  Greentouch investigating on green future networks.

This is the time for TRIMARAN to disseminate some of its innovations in these projects and their follow-ups. One of them has been identified as ‘Most Promising Technical Approach for 5G’ in the project METIS 2020, and continues being studied and promoted in the 5G-PPP Fantastic 5G project.

In 2015, the head of research of Orange Labs, Nicolas Demassieux, asks researchers in Orange to design a demo which is “visual” and more intuitive than … the oscilloscope screen. Orange will order to the start-up Luxondes a device which is unique in the world: a screen which shows in real time the electromagnetic waves that go through it. This device will enable the researchers to really show to the general public what is focusing and its potential to reduce the energy consumption of the future 5G networks.

To watch a video of the demo: Article in 01net with video of the experiment, june 2016 (in French).

In the picture below, thanks to two screens positioned in a perpendicular manner, one can observe in 3D, a focused spot generated by the prototype of TRIMARAN.



To know more, here are the publications of TRIMARAN:

  1. Phan-Huy, D. -T.; Siohan, P. ; Hélard, M.       “Make-it-real-and-anticirculating orthogonal space-time coding for MIMO OFDM/OQAM,” in Proc. 2015 IEEE 16th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Stockholm, 2015, pp. 61-65. Link.
  2. PHD thesis T. Dubois, 25th march 2013, INSA IETR, « Application du Retournement Temporel aux systèmes multi-porteuses : propriétés et performances ». Link.
  3. Prévotet, J.-C.; Kokar, Y.; Hélard, M.; Cruissière, M. “Implementation of a Time-Reversal MISO OFDM Test-Bed”, European Workshop on Testbed based wireless research (ETW), Stockholm, Sweden, 19 november 2014. Link.
  4. Prévotet, J.-C.; Kokar, Y.; Hélard, M.; Cruissière, M. “Implementation of a Time-Reversal MISO OFDM Test-Bed”, Wireless World Research Forum (WWRF) 2014, Guildford, UK, 26-28 september 2014, Link.
  5. Dubois, T. ; Hélard, M ; Crussière, M. ; Germond, C., “Performance of time reversal precoding technique for MISO-OFDM systems”, EURASIP 2014. Link.
  6. Malhouroux-Gaffet, N. ; Pajusco, P. ; Burghelea, R. ; Leray, C., “Capacity Gain of MIMO Systems with Microstructured Antenna Arrays,” European Conference on Antennas and Propagation (EUCAP) 2014, 6-11 april 2014, The Hague – The Netherlands. Link.
  7. Dubois, T. ; Hélard, M. ; Siohan, P. ; Crussière ; M., Jahan, B., “Efficient MISO system combining Time Reversal and OFDM/OQAM”, European Wireless (EW) 2014, 14 – 16 May 2014, Barcelone, Spain. Link.
  8. Phan-Huy, D.-T., Malhouroux-Gaffet, N.; Hélard, M. ; “Time Reversal for Ant Trails in wireless networks”, Global Telecommunications Conference (GLOBECOM) 2014, 8-12 December 2014, Austin, Texas, USA. Link.
  9. Phan-Huy, D.-T.; Kokar, Y.; Sarrebourse, T.; Malhouroux-Gaffet, N.; Pajusco, P.; Leray, C.; Gati, A.; Wiart, J.; “On the human exposure to radio frequency radiations expected from future small connected objects,” 2014 IEEE Globecom Workshops (GC Wkshps), Austin, TX, 2014, pp. 1186-1191. Link.
  10. Fu, H. ; Crussiere, M. ; Hélard, M., “Partial Channel Overlay in Moderate-Scale MIMO Systems Using WH Precoded OFDM”, in Proc. International Conference on Telecommunications (ICT) 2014, Lisbon, 5 – 7 May 2014, pp.16,21. Link.
  11. Phan-Huy, D.-T.; Sarrebourse, T.; Gati, A.; Wiart, J.; Helard, M., “Characterization of the confidentiality of a green time reversal communication system: Experimental measurement of the spy BER sink,” in Proc. IEEE Wireless Communications and Networking Conference (WCNC) 2013, Shanghai, 7-10 April 2013, pp.4783,4788. Link.
  12. Phan-Huy, D.-T.; Helard, M., “Large MISO beamforming for high speed vehicles using separate receive & training antennas,” in Proc. IEEE 5th International Symposium on Wireless Vehicular Communications (WiVeC) 2013, Dresden, 2-3 June 2013, pp.1,5. Link.
  13. Phan-Huy, D.-T.; Ben Halima, S.; Helard, M., “Dumb-to-perfect receiver throughput ratio maps of a time reversal wireless indoor system,” in Proc. 20th International Conference on Telecommunications (ICT), Casablanca, 6-8 May 2013, pp.1,5. Link.
  14. Dubois, T.; Helard, M.; Crussiere, M.; Maaz, I., “Time reversal applied to large MISO-OFDM systems,” in Proc. IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC) 2013, London, 8-11 Sept. 2013, pp.896,901. Link.
  15. Phan-Huy, D.-T.; Siohan, P.; Helard, M., ““Make-It-Real” precoders for MIMO OFDM/OQAM without inter carrier interference,” in Proc. IEEE Global Communications Conference (GLOBECOM) 2013, Atlanta, 9-13 Dec. 2013, pp.3920,3924. Link.
  16. Fu, H.; Crussiere, M.; Helard, M., “Spectral efficiency optimization in overlapping channels using TR-MISO systems,” in Proc. IEEE Wireless Communications and Networking Conference (WCNC), Shanghai, 7-10 April 2013, pp.3770,3775. Link .
  17. Dubois, T.; Hélard, M. and Crussière, M., “Time Reversal and OFDM combination: Guard Interval design, dimensioning and synchronisation aspects”, WWRF29, Berlin 23-25 octobre 2012. Link.
  18. Phan-Huy, D.-T. ; Helard, M., “Receive antenna shift keying for time reversal wireless communications,” in Proc. IEEE International Conference on Communications (ICC) 2012, Toronto, 10-15 June 2012, pp.4852,4856. Link.
  19. Lerosey, G. ; Leray, C.; Lemoult, F. ; de Rosny, J.; Tourin, A.; Fink, M., “Hybridization band gap based smart antennas: Deep subwavelength yet directional and strongly decoupled MIMO antennas,” in Proc. 6th European Conference on Antennas and Propagation (EUCAP) 2012, 26-30 March 2012, pp.2697, 2701. Link.
  20. Lerosey, G. ; Leray, C. ; Lemoult, F. ; de Rosny, J. ; Tourin, A., “Compact MIMO antenna arrays using metamaterial hybridization band gaps,” in Proc. International Symposium on Antennas and Propagation (ISAP) 2012, Nagoya, Oct. 29 2012-Nov. 2 2012, pp.774,777. Link.
  21. Lerosey, G. ; Leray, C. ; Lemoult, F. ; de Rosny, J. ; Tourin, A. and Fink, M., “Hybridization band gap based smart antennas : deep subwavelength yet directional and strongly decoupled MIMO antennas”, Advanced Electromagnetics Symposium (AES) 2012, Paris, 16-19 Avril 2012.
  22. Phan-Huy, D.-T. ; Ben Halima, S.; Helard, M., “Frequency Division Duplex Time Reversal,” in Proc. IEEE Global Telecommunications Conference (GLOBECOM) 2011, Houston, 5-9 Dec. 2011, pp.1, 5. Link.

To know more about contributions in European projects to 5G

METIS 2020 Project

  1. Most Promising Technical Approaches for 5G
  2. D. T. Phan-Huy, M. Sternad and T. Svensson, “Making 5G Adaptive Antennas Work for Very Fast Moving Vehicles,” in IEEE Intelligent Transportation Systems Magazine, vol. 7, no. 2, pp. 71-84, Summer 2015. Link.
  3. D-T Phan-Huy, T. Svensson, M. Sternad, W. Zirwas, B. Villeforceix, F. Karim and B. Sayrac,  “Connected Vehicles that use Channel Prediction Will Fully Take Advantage of 5G,” in Proc. 22nd ITS World Congress , Bordeaux, France, 5-9 October 2015. Link.
  4. D. T. Phan-Huy, M. Sternad and T. Svensson, “Adaptive large MISO downlink with Predictor Antenna array for very fast moving vehicles,” 2013 International Conference on Connected Vehicles and Expo (ICCVE), Las Vegas, NV, 2013, pp. 331-336. Link.

5G-PPP Fantastic-5G Project

  1. D.-T. Phan-Huy; M. Sternad; T. Svensson; W. Zirwas; B. Villeforceix; F. KARIM; S.-E. El Ayoubi, “5G on board: how many antennas do we need on connected cars?,” Globecom 2016, accepted.
  2. Air interface framework and specification of system level simulations


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