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Radio Networks

Members

Activities

In the recent years wireless technology has become an important part of our daily lives. As the demand of services from the users are constantly growing, current technology is pushed to its limits and new developments need to be addressed. In the Radio Networks research unit we want to contribute to this evolution by studying and developing algorithms for the lower layers of wireless networks.

For the moment, three areas are studied :

Research projects

AIOSAT

Autonomous Indoor Outdoor SafetyTracking system

Even though satellite-based positioning technology allows rescue workers to already operate efficiently, GPS availability, reliability, and accuracy are often poor during fire operations, for example due to thick smoke, dense forests, rough terrain and inside buildings. In this context, the objective of AIOSAT (Autonomous Indoor & Outdoor Safety Tracking System) is to progress beyond the state of the art by defining the AIOSAT concept that aims to overcome aforementioned limitations of GNSS usage in rescue interventions. For this purpose, GNSS positions are enhanced with EGNOS and fused with position information inferred from IMU and RF. The main paths to the goal will be to define 1) the end-user requirements for the AIOSAT system, 2) the Advanced Positioning Subsystem 3) the Communications Subsystem 4) the tracking and alerting (TA) application and, 5) build an integrated prototype system validated during field tests.

The RMA is responsible for the inter-distance measurement between the rescue workers based on UWB RF technology and the Communications Subsystem.


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ICMCIS

The ICMCIS is an international conference with 15 years of tradition. The intent of the conference is to create a forum for useful contacts and exchange ideas on development as well as implementation of advanced information and communications technologies and services in military systems. The conference gives a unique opportunity to discuss different points of view and share experience with colleagues from European and NATO nations involved in CIS. Previous conferences took place in many countries in Europe.

Steering Committee Chairman: Peter LENK, NATO Communications and Information Agency

Technical Program Committee Chairman: Bart SCHEERS, Royal Military Academy, Belgium

SafeShore

The main objective of the SafeShore project is to cover existing gaps in coastal border surveillance and increase internal security by preventing cross-border crime such trafficking in human beings and the smuggling of drugs. The project will develop an effective system to detect mini-RPAS when they cross the maritime border. To detect targets that are flying in low altitude, SafeShore will develop and deploy 3D LIDAR which will be integrated with passive acoustic sensors, passive radio detection and video analytics. The boats and humans on shore will be detected by a 2D LIDAR integrated with video analytics. Those technologies can be considered as low cost and ‘green’ technologies. One of SafeShore’s specific objectives will be to cover 1500-1800 meter along the coastal border.

The CISS department is responsible for the Radio passive monitoring system for detection and localization of small drones. The first part of this task is to determine the frequency in which the drone and the pilot operates. Once the frequency has been identified, an antenna array will be used to determine the angle of arrival of the transmitted signals.
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SIC07

The main objective of this study is to develop distributed time-slot assignment methods , and methods for time synchronization for tactical radio networks to have a fully functional TDMA based MAC, and evaluate their performance by simulations and by implementing on a hardware test-bench.

Study of solutions against security threats in the context of cognitive radios

This thesis studies jamming and anti-jamming tactics using cognitive radio technology. This research is mainly based on Q-learning artificial intelligence algorithm and game theory models to deal with diverse jamming tactics. A Software Defined Radio/Cognitive Radio test bed architecture is used to develop, test and validate the proposed algorithm.

Course BIPT

Course on "introduction to digital telecommunications", given to the technical personel of the "Belgian Institute for Postal services and Telecommunications" (BIPT) - Ellipse Building - Bâtiment C - Boulevard du Roi Albert II 35 - 1030 Brussels.

The course involves 8 days of teaching and 4 days of lab sessions, during the month of June 2012.

ICARUS

ICARUS is a EU FP7 project on robot assisted search and rescue (SAR) operations. As one of the partners, the CISS Department contributed to the design and implementation of a wireless communications system to interconnect the unmanned platforms, command and control stations and rescuers. The key objective was to obtain a self-organizing network of mobile devices adapting to the dynamics of the environment.
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F11/01

Automation of audio processes in the collection of operational SIGINT.

MRC04

The aim of this project is to study the performance measures (throughput, delay, jitter) of Packet Data Radio Networks (PDRN). PDRNs will form the mobile backbone of the tactical communication network for the next generation of combat systems. Analytical and simulation models are combined to evaluate the characteristics of both synthetic and captured traffic streams considering a realistic scenario, i.e. the topology of the radio means and the physical surroundings.

C4/19

In this study, three main objectives are pursued: 1) make a state-of-the-art survey of software radio techniques and cognitive radios, 2) contributing in the domain of spectrum management for cognitive radios in the UHF and VHF frequency bands and 3) contributing to waveform design for cognitive radios in a adhoc tactical network context.

F09/05

This study mainly focusses on how to retrieve the position of the sensor nodes of a wireless sensor network and with which precision this can be done (assuming the nodes don’t have a GPS module on board). How the topology of the wireless network could be controlled in order to optimise the network for given scenarios is also investigated. The goal of this study is not only to have a theoretical approach of the problem, but also to implement the most promising methods or algorithms on a real sensor network.

Publications

  1. Y. Livran, V. Le Nir, S. Couturier, M. Suchanski, P. Kaniewski, J. Romanik, A. Hamilton, P. Howland, and M. Tracy. Electromagnetic Environment Situational Awareness. In International Conference on Military Communications and Information Systems (ICMCIS'2021), Virtual Edition, May 2021.
  2. K. Pärlin, T. Riihonen, V. Le Nir, M. Bowyer, T. Ranström, E. Axell, B. Asp, R. Ulman, M. Tschauner, and M. Adrat. Full-Duplex Tactical Information and Electronic Warfare Systems. IEEE Communication Magazine, 59(8):73-79, August 2021.
  3. M. Adrat, R. Keller, M. Tschauner, S. Wilden, V. Le Nir, R. Taneli, M. Bowyer, and K. Pärlin. Full-Duplex Radio – Increasing the Spectral Efficiency for Military Applications. In International Conference on Military Communications and Information Systems (ICMCIS'2019), Budva, Montenegro, May 2019.
  4. V. Le Nir. Effect of Log-Normal Shadowing on RSS-based Single and Multiple Transmitter Localization for Radio Environment Map. In The 1st Electrosense Workshop, Leuven, Belgium, April 2019.
  5. V. Le Nir and B. Scheers. DAP17-01: Multi Band Efficient Networks for Ad Hoc Communications. In 4th CWO Poster Session, Brussels, Belgium, May 2019.
  6. S. Basak and B. Scheers. Passive radio system for real-time drone detection and doA estimation. In 2018 International Conference on Military Communications and Information Systems (ICMCIS), pages 1-6, May 2018.
  7. M. H. Chaudhary and B. Scheers. Practical One-Way Time Synchronization Schemes With Experimental Evaluation. In IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Kalamata, Greece, June 2018.
  8. S. Couturier, T. Bräysy, B. Buchin, J. Krygier, V. Le Nir, N. Smit, T. Tuukkanen, and E. Verheul. End-to-End optimization for Tactical Cognitive Radio Networks. In International Conference on Military Communications and Information Systems (ICMCIS'2018), Warsaw, Poland, May 2018.
  9. Pieterjan De Meulemeester, Luc Bontemps, Bart Scheers, and Guy A. E. Vandenbosch. Synchronization Retrieval and Reconstruction of Information Displays. In 27th URSI Benelux Forum, Delft, The Netherlands, 2018.
  10. V. Le Nir and B. Scheers. Enhancement Technique for Military Waveforms based on Cognitive Radio. In Workshop on AI and Cognitive Technologies for Radar, Comms and EW, Brussels, Belgium, December 2018.
  11. V. Le Nir and B. Scheers. Multiple Jammer Localization and Tranmission Power Estimation for Radio Environment Map. In International Conference on Military Communications and Information Systems (ICMCIS'2018), Warsaw, Poland, May 2018.
  12. P. De Meulemeester, L. Bontemps, B. Scheers, and G. A. E. Vandenbosch. Synchronization retrieval and image reconstruction of a video display unit exploiting its compromising emanations. In 2018 International Conference on Military Communications and Information Systems (ICMCIS), pages 1-7, May 2018.
  13. F. Slimeni, Z. Chtourou, B. Scheers, V. Le Nir, and R. Attia. Cooperative Q-learning based channel selection for cognitive radio networks. Wireless Networks, pages 1-11, May 2018.
  14. T. Tuukkanen, S. Couturier, B. Buchin, T. Bräysy, J. Krygier, E. Verheul, V. Le Nir, and N. Smit. Assessment of Cognitive Radio Networks through Military Capability Development Viewpoint. In International Conference on Military Communications and Information Systems (ICMCIS'2018), Warsaw, Poland, May 2018.
  15. P. Warpechowski and V. Le Nir. Introduction to NBWF Demonstration: Results on the Interoperability Tests for the NATO NBWF. In International Conference on Military Communications and Information Systems (ICMCIS'2018), Warsaw, Poland, May 2018.
  16. T. Bräysy, T. Tuukkanen, S. Couturier, E. Verheul, N. Smit, B. Buchin, V. Le Nir, and J. Krygier. Network Management Issues in Military Cognitive Radio Networks. In International Conference on Military Communications and Information Systems (ICMCIS'2017), Oulu, Finland, May 2017.
  17. M. H. Chaudhary and B. Scheers. Extended HUDSAP for Distributed MAC Scheduling in Mobile Ad-Hoc Networks. In Int. Conf. on Military Communications and Information Systems (ICMCIS), Oulu, Finland, May 2017.
  18. V. Le Nir and B. Scheers. Belgian NATO Narrow Band Waveform for Tactical Radios. In 2nd CWO Poster Session, Brussels, Belgium, April 2017.
  19. V. Le Nir and B. Scheers. Low Complexity Generic Receiver for the NATO Narrow Band Waveform. In International Conference on Military Communications and Information Systems (ICMCIS'2017), Oulu, Finland, May 2017. Best Paper Award.
  20. J. Sanchez, J. Cordero, H. Chaudhary, B. Scheers, and R. Riobo. Tactical Communications for Cooperative SAR Robot Missions. In Search and Rescue Robotics - From Theory to Practice, chapter 7. InTech, August 2017.
  21. F. Slimeni. Study of solutions against security threats in the context of cognitive radio. PhD thesis, Royal Military Academy and EPT University of Carthage, October 2017.
  22. M. H. Chaudhary and B. Scheers. Dynamic Channel and Transmit-Power Adaptation of WiFi Network in Search and Rescue Operations. In Int. Conf. on Military Communications and Information Systems (ICMCIS), Brussels, Belgium, May 2016.
  23. M. H. Chaudhary and B. Scheers. Software-Defined Wireless Communications and Positioning Device for IoT Development. In Int. Conf. on Military Communications and Information Systems (ICMCIS), Brussels, Belgium, May 2016.
  24. S. Couturier, T. Bräysy, B. Buchin, L. Giupponi, J. Krygier, V. Le Nir, T. Tuukkanen, and E. Verheul. NATO IST-140 RTG-065 Cognitive Radio Networks - Efficient Solutions for Routing, Topology Control, Data Transport, and Network Management. In 2016 Wireless Innovation Forum European Conference on Communications Technologies and Software Defined Radio (WInnComm-Europe'2016), Paris, France, October 2016.
  25. V. Le Nir and B. Scheers. Carrier Frequency and Phase Synchronization for Burst-Mode Continuous Phase Modulation. Technical report, CISS, Royal Military Academy (RMA), Brussels, Belgium, August 2016.
  26. V. Le Nir and B. Scheers. Low-Complexity Generic Receiver for Burst-Mode Continuous Phase Modulation. Technical report, CISS, Royal Military Academy (RMA), Brussels, Belgium, February 2016.
  27. V. Le Nir and B. Scheers. Voice Transmission over NATO Narrow Band Waveform Physical Layer with Low-Cost Software Defined Radio Platforms. In International Conference on Military Communications and Information Systems (ICMCIS'2016), Brussels, Belgium, May 2016.
  28. F. Slimeni, V. Le Nir, B. Scheers, Z. Chtourou, and R. Attia. Optimal Power Allocation over Parallel Gaussian Channels in Cognitive Radio and Jammer Games. IET Communications, 10(8):980-986, May 2016.
  29. F. Slimeni, B. Scheers, Z. Chtourou, V. Le Nir, and R. Attia. A modified Q Learning algorithm to solve Cognitive Radio jamming attack. Special Issue on RFID Applications in the Internet of Things, International Journal of Embedded Systems, 2016.
  30. F. Slimeni, B. Scheers, V. Le Nir, Z. Chtourou, and R. Attia. Closed form Expression of the Saddle Point in Cognitive Radio and Jammer Power AllocationGame. In 11th International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM'2016), Grenoble, France, May 2016.
  31. F. Slimeni, B. Scheers, V. Le Nir, Z. Chtourou, and R. Attia. Learning multi-channel Power Allocation against smart jammer in Cognitive Radio Networks. In International Conference on Military Communications and Information Systems (ICMCIS'2016), Brussels, Belgium, May 2016. Young Scientist Best Paper Award.
  32. M. H. Chaudhary and B. Scheers. Energy Efficient Quantization of Correlated Noisy Observations of a Sensor. In IEEE Int. Conf. on Communications (ICC), London, UK, June 2015.
  33. S. Couturier, J. Krygier, O. Bentstuen, and V. Le Nir. Challenges for Network Aspects of Cognitive Radio. In International Conference on Military Communications and Information Systems (ICMCIS'2015), Cracow, Poland, May 2015.
  34. V. Le Nir and B. Scheers. Evaluation of Open-source Software Frameworks for High Fidelity Simulation of Cognitive Radio Networks. In International Conference on Military Communications and Information Systems (ICMCIS'2015), Cracow, Poland, May 2015.
  35. V. Le Nir and B. Scheers. On the Implementation of the NATO Narrow Band Waveform with Low-Cost Software Defined Radio Platforms. In 5th Annual Tactical Radio Workshop: Coalition Interoperability at the 2015 Wireless Innovation Forum European Conference on Communications Technologies and Software Defined Radio (WInnComm-Europe'2015), Erlangen, Germany, October 2015.
  36. V. Le Nir and B. Scheers. Robust Blind Carrier Frequency Synchronisation for Direct Sequence Spread Spectrum Systems. IET Electronic Letters, 51(5):425-427, March 2015.
  37. B. Scheers, D. Teguig, and V. Le Nir. Modified Anderson-Darling Detector for Spectrum Sensing. IET Electronic Letters, 51(25):2156-2158, December 2015.
  38. B. Scheers, D. Teguig, and V. Le Nir. Wideband Spectrum Sensing technique based on Goodness-of-Fit testing. In International Conference on Military Communications and Information Systems (ICMCIS'2015), Cracow, Poland, May 2015.
  39. F. Slimeni, B. Scheers, and Z. Chtourou. Security Threats in Military Cognitive Radio Networks. In International Conference on Military Communications and Information Systems (ICMCIS'2015), Cracow, Poland, May 2015.
  40. F. Slimeni, B. Scheers, Z. Chtourou, and V. Le Nir. Jamming Mitigation in Cognitive Radio Networks using a Modified Q-learning Algorithm. In International Conference on Military Communications and Information Systems (ICMCIS'2015), Cracow, Poland, May 2015.
  41. F. Slimeni, B. Scheers, Z. Chtourou, V. Le Nir, and R. Attia. Cognitive Radio Jamming Mitigation using Markov Decision Process and Reinforcement Learning. In International Conference on Advanced Wireless Information & Communications Technologies (AWICT'2015), Sousse, Tunisia, October 2015.
  42. D. Teguig. Cooperative Spectrum Sensing Algorithms For Cognitive Radio Networks. PhD thesis, Royal Military Academy and Université Libre de Bruxelles, October 2015.
  43. D. Teguig, V. Le Nir, and B. Scheers. Spectrum Sensing Method based on Likelihood Ratio Goodness-of-Fit Test. IET Electronic Letters, 51(3):253-255, February 2015.
  44. D. Teguig, B. Scheers, V. Le Nir, and F. Horlin. Consensus Algorithms for Distributed Spectrum Sensing Based on Goodness of Fit Test in Cognitive Radio Networks. In International Conference on Military Communications and Information Systems (ICMCIS'2015), Cracow, Poland, May 2015.
  45. M. H. Chaudhary and B. Scheers. DMR Implementation on SDR Platform for Control of Unmanned Devices and Cognitive Management of WiFi Network in Search and Rescue Missions. In NATO IST/RSY Symposium on Cognitive Radio & Future Networks, the Hague, the Netherlands, May 2014.
  46. V. Le Nir and B. Scheers. CogWave: Open-source Software Framework for Cognitive Radio Waveform Design. In IST-123 Symposium on Cognitive Radio and Future Networks, The Hague, The Netherlands, May 2014. Best Contribution Award.
  47. V. Le Nir and B. Scheers. Description of a Cognitive Radio Testbed based on USRP Platforms and CogWave. In 9th International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM'2014), Oulu, Finland, June 2014.
  48. D. Teguig, V. Le Nir, and B. Scheers. Spectrum Sensing Method based on Goodness of Fit Test using Chi-Square Distribution. IET Electronic Letters, 50(9):713-715, April 2014.
  49. D. Teguig, B. Scheers, and V. Le Nir. Evolutionary Theoretical Game for Cooperative Spectrum Sensing in Cognitive Radio Netowkrs: A Survey. In IST-123 Symposium on Cognitive Radio and Future Networks, The Hague, The Netherlands, May 2014.
  50. D. Teguig, B. Scheers, V. Le Nir, and F. Horlin. Spectrum Sensing Method Based on the Likelihood Ratio Goodness of Fit Test under Noise Uncertainty. International Journal of Engineering Research & Technology (IJERT), 3(9):488-494, September 2014.
  51. M. H. Chaudhary and B. Scheers. Joint decentralized slot allocation and time synchronization in a TDMA based MAC. In Military Communications and Information Systems Conference (MCC), St.-Malo, France, October 2013.
  52. M. H. Chaudhary and B. Scheers. Progressive Decentralized TDMA Based MAC: Joint Optimization of Slot Allocation and Frame Lengths. In IEEE Military Communications Conf. (MILCOM), San Diego, CA, USA, November 2013.
  53. V. Le Nir and B. Scheers. CogWave: Open-source Software Platform for Cognitive Radio Waveform Design. Technical report, CISS, Royal Military Academy (RMA), Brussels, Belgium, March 2013.
  54. V. Le Nir and B. Scheers. CogWave: Open-source Software Platform for Cognitive Radio Waveform Design. In Workshop on Cognitive Radio, Saint-Malo, France, October 2013.
  55. V. Le Nir and B. Scheers. DADS with short spreading sequences for high data rate communications or improved BER performance. In Military Communications and Information Systems Conference (MCC'2013), Saint-Malo, France, October 2013.
  56. B. Scheers. Introduction of Dynamic Spectrum Access Technology in NATO Europe Tactical Communications. In IEEE Military Communications Conference (MILCOM'2013), pages 737-742, San Diego, CA, USA, November 2013.
  57. D. Teguig, B. Scheers, and V. Le Nir. Throughput Optimization for Cooperative Spectrum Sensing in Cognitive Radio Networks. In 7th International Conference on Next Generation Mobile Apps, Services and Technologies (NGMAST'2013), Prague, Czech Republic, September 2013.
  58. M. H. Chaudhary and B. Scheers. High spatial-reuse distributed slot assignment protocol for wireless ad hoc networks. In Military Communications and Information Systems Conference (MCC), Gdansk, Poland, October 2012.
  59. V. Le Nir and B. Scheers. Dynamic Spectrum Management for the Coexistence of Cognitive Tactical Radio Networks. In 12th annual SMi International Software Radio symposium, London, United Kingdom, June 2012.
  60. V. Le Nir and B. Scheers. Implementation of an adaptive OFDMA PHY/MAC on USRP platforms for a cognitive tactical radio network. In Military Communications and Information Systems Conference (MCC'2012), Gdańsk, poland, October 2012.
  61. B. Scheers, A. Mahoney, and H. Åkermark. A Realistic Roadmap for the Introduction of Dynamic Spectrum Management in Military Tactical Radio Communication. In Military Communications and Information Systems Conference (MCC'2012), Gdańsk, poland, October 2012.
  62. D. Teguig, B. Scheers, and V. Le Nir. Data Fusion Schemes for Cooperative Spectrum Sensing in Cognitive Radio Networks. In Military Communications and Information Systems Conference (MCC'2012), Gdańsk, poland, October 2012.
  63. S. D'hondt, B. Scheers, and V. Le Nir. Implementation of Dynamic Spectrum Allocation for Cognitive Radio Networks based on Iterative Water Filling in OMNeT++/MiXiM. In 4th International Workshop on OMNeT++ (OMNET-2011), Barcelona, Spain, March 2011.
  64. V. Le Nir and B. Scheers. Improved Coexistence between Multiple Cognitive Tactical Radio Networks by an Expert Rule based on Sub-channel Selection. In Wireless Innovation Forum European Conference on Communications Technologies and Software Defined Radio (SDR'11-WInnComm-Europe), Brussels, Belgium, June 2011.
  65. V. Le Nir and B. Scheers. Improved DADS Performance with Noise Reduction by Averaging. Technical report, CISS, Royal Military Academy (RMA), Brussels, Belgium, December 2011.
  66. V. Le Nir and B. Scheers. Iterative Waterfilling Algorithm with Sub-channel Selection for the Coexistence of Multiple Cognitive Tactical Radio Networks. In Military Communications and Information Systems Conference (MCC'2011), Amsterdam, Nederlands, October 2011.
  67. V. Le Nir and B. Scheers. Multiple Input Multiple Output Iterative Water-Filling Algorithm for Multiple Broadcast Networks Distributing Only Common Information. Technical report, CISS, Royal Military Academy (RMA), Brussels, Belgium, December 2011.
  68. V. Le Nir and B. Scheers. Performance of Delay and Add Direct Sequence Spread Spectrum Modulation Scheme with Fast Frequency Hopping in Frequency Selective Rayleigh Channels. In IEEE Military Communications Conference (MILCOM'2011), Baltimore, United States, November 2011.
  69. V. Le Nir and B. Scheers. Autonomous Dynamic Spectrum Management for Coexistence of Multiple Cognitive Tactical Radio Networks. In 5th International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM'2010), Cannes, France, June 2010.
  70. V. Le Nir and B. Scheers. Coexistence of Tactical Cognitive Radio Networks. In SDR Forum European Reconfigurable Radio Technologies Workshop (ERRT'2010), Mainz, Germany, June 2010.
  71. V. Le Nir and B. Scheers. Distributed Power Allocation for Parallel Broadcast Channels with Only Common Information in Cognitive Tactical Radio Networks. EURASIP Journal on Wireless Communications and Networking Volume 2010, Article ID 172013, 10 pages doi:10.1155/2010/172013, December 2010.
  72. V. Le Nir and B. Scheers. Resource Allocation for Parallel Gaussian MIMO Wire-tap Channels. IEEE Communications Letters, 14(12):1092-1094, December 2010.
  73. B. Scheers and V. Le Nir. A Modified Direct-Sequence Spread Spectrum Modulation Scheme for Burst Transmissions. In Military Communications and Information Systems Conference (MCC'2010), Wroclaw, Poland, September 2010.
  74. B. Scheers and V. Le Nir. Pseudo-Random Binary Sequence Selection for Delay and Add Direct Sequence Spread Spectrum Modulation Scheme. IEEE Communications Letters, 14(11):1002-1004, November 2010.
  75. S. Couturier and B. Scheers. The State of the Art of Dynamic Spectrum Access. In Military Communications and Information Systems Conference (MCC'2011), Prague, Czech Republic, September 2009.
  76. V. Le Nir and B. Scheers. Cognitive Radio: A State of the Art. In Communication, Information Systems & Sensors (CISS) day, page 1, Brussels, Belgium, October 2009.
  77. V. Le Nir and B. Scheers. Cognitive Radio Systems: State of the art. Technical report, CISS, Royal Military Academy (RMA), Brussels, Belgium, September 2009.
  78. Ben Lauwens, Bart Scheers, and Antoine Van de Capelle. Throughput Analysis of Multi-Hop CSMA/CA Wireless Networks. In 2008 IEEE Sarnoff Symposium, pages 1-6. IEEE, April 2008.
  79. B. Lauwens, B. Scheers, and A. V. de Capelle. Buffer Occupation Probability of Trace-Driven Background Streams in Hybrid Simulation. In IEEE International Conference on Communications, pages 581-587. IEEE, June 2007.
  80. V. Le Nir. Etude et optimisation des systèmes multi-antennes associés à des modulations multiporteuses. PhD thesis, Institut National des Sciences Appliquées de Rennes, November 2004.