Welcome to the Institute of Digital Signal Processing!

Cognitive Radio

ITU (International Telecommunication Union) defines CR (Cognitive Radio) as a radio system employing technology with (a) cognitive capability to obtain knowledge of its environment, established policies, and its internal state, (b) reconfigurable capability to dynamically and autonomously adjust its operational parameters and protocols to achieve predefined objectives and (c) learning capability to learn from the results obtained.

A CR device can therefore be seen as an extremely flexible SDR (Software Defined Radio) platform, extended by mechanisms for spectrum sensing and awareness, data base access to gather additional environmental information, and a cognitive engine for resource allocation and dynamic spectrum management.

The fundamental need for CR comes on the one hand side from the densely regulated spectrum caused by traditional fixed frequency allocation and on the other hand side from the rapidly increasing demand for spectrum caused by mobile internet devices, in particular the smartphone. This demanding current situation characterizes the challenging real-world scenario to sustainably provide enough bandwidth for mobile internet services.

CR related research at DSV is not only restricted to methods and algorithms for cognitive devices, but also focuses on implementation and verification of algorithms on commercial SDR platforms, mainly intended for small cell base stations. One related crucial aspect of our research is to embed the cognitive mechanisms into existing and future communication standards, in particular future releases of LTE (Long Term Evolution). For instance, within two major public projects, DSV contributes to cognitive LTE enhancements like spectrum sensing and dynamic spectrum allocation in TV white spaces and, even more challenging, setting up an ad-hoc communication infrastructure by cognitive means in emergency scenarios.

Last but not least our CR research is of general nature: while DSV’s current focus is on cellular communications, the CR principles and our developed CR know-how and toolboxes can be applied to any carrier frequency, e.g. ranging from even below Megahertz up to the Terahertz range.

Some representative questions being addressed in our CR research:


Novel Spectrum Usage Paradigms for 5G

The white paper Novel Spectrum Usage Paradigms for 5G has been published in IEEE TCCN Special Interest Group on Cognitive Radio for 5G. More detailed information can be found in IEEE TCCN webpage.


Publications

  • Downlink frequency reuse and hopping for OFDMA femtocells
    Z. Zhao, T. Kaiser, and A. Wilzeck, “Downlink frequency reuse and hopping for OFDMA femtocells,” Frequenz, vol.64, no.9-10, pp.185-190, 2010.
  • Cyclostationary Beacon for Assisting Spectrum Sensing in Opportunistic Spectrum Access
    H. Cao, Q. Cai, J. P. Miranda, T. Kaiser, “Cyclostationary Beacon for Assisting Spectrum Sensing in Opportunistic Spectrum Access," Majlesi Journal of Electrical Engineering, Vol 5, No 1, March 2011.
  • Cognitive Radio & Networks in the Perspective of Industrial Wireless Communications
    T. Kaiser, M. D. Perez-Guirao, and A. Wilzeck, “Cognitive Radio & Networks in the Perspective of Industrial Wireless Communications” (invited), 2nd International Workshop on Cognitive Radio & Advanced Spectrum Management (CogART 2009) within Wireless VITAE 2009, Aalborg Congress and Culture Centre, Aalborg, Denmark, May 18-19, 2009.
  • A Real-Time Pre-MIMO-LTE Software Radio Testbed
    R. Chen, Q. Cai, K. Alecke, O. Lazar, T. Kaiser, “A Real-Time Pre-MIMO-LTE Software Radio Testbed”, 15th European Signal Processing Conference, Sept. 3-7, 2007, Poznan, Poland.
  • A Distributed Simulation System and its Application for 3GPP LTE Indoor Scenarios
    Q. Cai, Z. Zhao, S. Sczyslo, A. Wilzeck, C. Senger, T. Kaiser, “A Distributed Simulation System and its Application for 3GPP LTE Indoor Scenarios”, International Symposium on Wireless Pervasive Computing 2008, May 7-9, 2008, Santorini, Greece.
  • Pulse Rate Adaptive Multiple-Access Scheme for Cognitive Autonomous IR-UWB Networks
    M.D. Perez-Guirao, R. Luebben, T. Kaiser, “Pulse Rate Adaptive Multiple-Access Scheme for Cognitive Autonomous IR-UWB Networks”, IEEE ICUWB International Conference on Ultra-Wideband, September 10-12, 2008, Hanover, Germany.
  • CA-MAC: Autonomous, Cognitive MAC for IR-UWB Networks
    M.D. Perez-Guirao, T. Kaiser, K. Jobmann, B. Kull “CA-MAC: Autonomous, Cognitive MAC for IR-UWB Networks”, Second International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CrownCom 2007), August 1-3, 2008, Orlando, Florida, USA.
  • Cyclostationary multitone beacon signal for opportunistic spectrum access
    H. Cao, Q. Cai, J. P. Miranda, T. Kaiser, “Cyclostationary multitone beacon signal for opportunistic spectrum access”, 4th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, Hannover, Germany, June 22-24, 2009.
  • Practical Issues in Spectrum Sensing for Multi-Carrier System Employing Pilot Tones
    H. Cao, S. Daoud, A. Wilzeck, T. Kaiser, “Practical Issues in Spectrum Sensing for Multi-Carrier System Employing Pilot Tones,” 3rd Int. Symp. Applied Sciences in Biomedical and Communication Technologies (ISABEL 2010), Rome, Italy, 7-10 Nov. 2010.
  • Femtocell Spectrum Access Underlaid in Fractional Frequency Reused Macrocell
    Z. Zhao, F. Zheng, A. Wilzeck, T. Kaiser, “Femtocell Spectrum Access Underlaid in Fractional Frequency Reused Macrocell,” IEEE 2011 Int. Conf. Communications (Workshop on Heterogeneous Networks), Kyoto, Japan, 5-9 Jun. 2011.
  • Analysis of the Influence of OFDM Sidelobe Interference on Femto Rich Systems
    Z. Zhao, C. Thein, F. Zheng, T. Kaiser, “Analysis of the Influence of OFDM Sidelobe Interference on Femto Rich Systems,” 9th Intl. Symp. Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt'11), Workshop on Indoor and Outdoor Femto Cells, Princeton, NJ, USA, 9-13 May 2011.
  • Multicarrier transmission schemes in cognitive radio
    W. Jiang, Multicarrier transmission schemes in cognitive radio, 2012 Int. Symp. Signals, Systems and Electronics, Potsdam, Germany, 3-5 Oct. 2012.
  • DSSS differential GMSK with space-time modulation for robust mobile data links
    H. Cao, F. Maier, A. Wilzeck, and T. Kaiser, “DSSS differential GMSK with space-time modulation for robust mobile data links,” in 2012 IEEE Wireless Communications and Networking Conference (WCNC 2012), Paris, France, 1-4 April 2012.
  • Measurement and ray-tracing of wideband indoor channel in UHF TV white space
    H. Cao, Z. Zhao, W. Ni, M. El-Hadidy, and T. Kaiser, “Measurement and ray-tracing of wideband indoor channel in UHF TV white space,” in 4th International Conference on Cognitive Radio and Advanced Spectrum Management (CogART 2011), Barcellona, Spain, 26-29 Oct. 2011.
  • Key issues towards beyond LTE-Advanced systems with cognitive radio
    W. Jiang, H. Cao, T. T. Nguyen, A. B. Güven, Y. Wang, Y. Gao, A. Kabbani, M. Wiemeler, T. Kreul, F. Zheng, T. Kaiser, “Key issues towards beyond LTE-Advanced systems with cognitive radio,” IEEE 14th Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Darmstadt, Germany, 16-19 June 2013.
  • The design of an LTE-A system enhanced with cognitive radio
    H. Cao, W. Jiang, T. T. Nguyen, A. B. Güven, Y. Wang, Y. Gao, A. Kabbani, M. Wiemeler, T. Kreul, F. Zheng, and T. Kaiser, "The design of an LTE-A system enhanced with cognitive radio," 21st European Signal Processing Conf., Marrakech, Morocco, 9-13 Sept. 2013
  • Spectrum Awareness Scheme of the Rapidly Deployable eNodeB for Unexpected and Temporary Events
    H. Cao, W. Jiang, T. Javornik, M. Wiemeler, T. T. Nguyen, and T. Kaiser, “Spectrum Awareness Scheme of the Rapidly Deployable eNodeB for Unexpected and Temporary Events,” in 1st IEEE International Workshop on Emerging Technologies and Trends for Public Safety Communications (ETPSC 2013), Co-located with IEEE CAMAD 2013, Berlin, Germany, 27 Sept. 2013.
  • A Robust Radio Access Technology Classification Scheme with Practical Considerations
    H. Cao, W. Jiang, M. Wiemeler, T. Kaiser, and J. Peissig, “A Robust Radio Access Technology Classification Scheme with Practical Considerations,” in 2013 IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2013), London, UK, 8-11 Sept. 2013.
  • Multi-channel Robust Spectrum Sensing with Low-complexity Filter Bank Realization
    H. Cao, W. Jiang, and T. Kaiser, “Multi-channel Robust Spectrum Sensing with Low-complexity Filter Bank Realization,” in 2013 IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2013), London, UK, 8-11 Sept. 2013.
  • Robust Spectrum Sensing of DVB-T2 Signal Using the First Preamble Symbol
    T. T. Nguyen, H. Cao, A. B. Güven, Y. Gao, A. Kabbani, T. Kreul, and T. Kaiser, “Robust Spectrum Sensing of DVB-T2 Signal Using the First Preamble Symbol”, 2013 Int. Conf. Advanced Technologies for Communications, Hochiminh City, Vietnam, 16-18 Oct., 2013.
  • Power Optimal Allocation in Decode-and-Forward Opportunistic Relaying
    W. Jiang, H. Cao, and T. Kaiser, “Power Optimal Allocation in Decode-and-Forward Opportunistic Relaying”, IEEE Wireless Communications and Networking Conf. (WCNC 2014), Istanbul, Turkey, 6-9 April 2014.
  • Analysis of Generalized Selection Combining in Cooperative Networks with Outdated CSI
    W. Jiang, H. Cao, and T. Kaiser, “Analysis of Generalized Selection Combining in Cooperative Networks with Outdated CSI”, IEEE Wireless Communications and Networking Conf. (WCNC 2014), Istanbul, Turkey, 6-9 April 2014.
  • Opportunistic Space-Time Coding to Exploit Cooperative Diversity in Fast-Fading Channels
    W. Jiang, H. Cao, and T. Kaiser, “Opportunistic Space-Time Coding to Exploit Cooperative Diversity in Fast-Fading Channels”, 2014 IEEE Int. Conf. Communications (ICC), Sydney, Australia, 10-14 June 2014.
  • Cognitive radio - A current snapshot and some thoughts on commercialization for future cellular systems
    T. Kaiser, H. Cao, W. Jiang, F. Zheng, “Cognitive radio – A current snapshot and some thoughts on commercialization for future cellular systems”, Journal of Signal Processing Systems for Signal Image and Video Technology, vol.73, pp.217-225, 2013.
  • Parallel In-band Signal Detection With Self-interference Suppression for Cognitive LTE
    H. Cao, W. Jiang and T. Kaiser, “Parallel In-band Signal Detection With Self-interference Suppression for Cognitive LTE”, IEEE Wireless Communications and Networking Conf. (WCNC 2014), Istanbul, Turkey, 6-9 April 2014.
  • An MGF-Based Performance Analysis of Opportunistic Relay Selection with Outdated CSI
    W. Jiang, H. Cao, and T. Kaiser, “An MGF-Based Performance Analysis of Opportunistic Relay Selection with Outdated CSI”, IEEE Vehicular Technology Conf. (VTC 2014-Spring), Seoul, South Korea, 18 - 21 May 2014.
  • Opportunistic Relaying over Aerial-to-Terrestrial and Device-to-Device Radio Channels
    W. Jiang, H. Cao, L. Goratti, M. Wiemeler, and T. Kaiser, "Opportunistic Relaying over Aerial-to-Terrestrial and Device-to-Device Radio Channels," in Proc. 2014 IEEE Int. Conf. Communications (ICC), Sydney, Australia, 10-14th June 2014.
  • Achieving High Reliability in Aerial-Terrestrial Networks: Opportunistic Space-Time Coding
    W. Jiang, H. Cao, M. Wiemeler, and T. Kaiser, "Achieving High Reliability in Aerial-Terrestrial Networks: Opportunistic Space-Time Coding", in Proc. European Conference on Networks and Communications (EuCNC’2014), Bologna, Italy, 23-25th June, 2014.
  • Interference Alignment for OFDM Cognitive Radio Networks in TV White Space Spectrum
    M. El-Absi, A. Güven, T. Kaiser, "Interference Alignment for OFDM Cognitive Radio Networks in TV White Space Spectrum," 18th Int. OFDM-Workshop 2014 (InOWo14), Essen, Germany, 27-28 Aug. 2014.
  • Optimal Resource Allocation Based on Interference Alignment for OFDM and FBMC MIMO Cognitive Radio Systems
    M. El-Absi and T. Kaiser, "Optimal Resource Allocation Based on Interference Alignment for OFDM and FBMC MIMO Cognitive Radio Systems," Proc. 23rd European Conf. on Networks and Communications (EuCNC'2014), Bologna, Italy, 23-25 June 2014.
  • Interference Alignment Based Resource Management in MIMO Cognitive Radio Systems
    M. El-Absi, M. Shaat, F. Bader, and T. Kaiser, "Interference Alignment Based Resource Management in MIMO Cognitive Radio Systems", Proc. IEEE 2014 20th European Wireless Conference (EW2014), Barcelona, Spain, 14-16 May 2014.
  • Exploiting Periodical Peaks of Autocorrelation of Pilot-Added OFDM Signals for Enhanced Spectrum Sensing Algorithms
    T. T. Nguyen, H. Cao, T. Kreul, and T. Kaiser, "Exploiting Periodical Peaks of Autocorrelation of Pilot-Added OFDM Signals for Enhanced Spectrum Sensing Algorithms", 18th Int. OFDM-Workshop 2014 (InOWo14), Essen, Germany, 27-28 Aug. 2014.
  • Interference Alignment with Frequency-Clustering for Efficient Resource Allocation in Cognitive Radio Networks
    M. El-Absi, M. Shaat, F. Bader, and T. Kaiser, "Interference Alignment with Frequency-Clustering for Efficient Resource Allocation in Cognitive Radio Networks," IEEE Global Communications Conf. (Globecom'2014), Austin, TX USA, 8-12 Dec. 2014.
  • Spectral Efficiency Comparison of OFDM/FBMC for Interference Alignment Based Power Loading in MIMO Cognitive Radio Systems
    M. El-Absi, M. Shaat, F. Bader, and T. Kaiser, “Spectral Efficiency Comparison of OFDM/FBMC for Interference Alignment Based Power Loading in MIMO Cognitive Radio Systems,” 11th Int. Symp. Wireless Communication Systems (ISWCS'2014). Barcelona, Spain, Aug. 2014.
  • Dynamic spectrum access and cognitive radio: A current snapshot
    W. Jiang, H. Cao, G. Sun, T. Kaiser, F. Zheng, Dynamic spectrum access and cognitive radio: A current snapshot, pp.24-34. in IEEE TCCN Special Interest Group Cognitive Radio in 5G White Paper - Novel Spectrum Usage Paradigms for 5G (ed. by M. Mueck, W. Jiang, G. Sun, H. Cao, E. Dutkiewicz, S. Choi), November 4th, 2014.
  • Energy-Efficient Resource Allocation Based on Interference Alignment in MIMO-OFDM Cognitive Radio Networks
    M. El-Absi, A. Ali, M. El-Hadidy, T. Kaiser, "Energy-Efficient Resource Allocation Based on Interference Alignment in MIMO-OFDM Cognitive Radio Networks," Int. Conf. Cognitive Radio Oriented Wireless Networks (CROWNCOM), Qatar, April 2015.
  • Implementation Aspects of a DSP-Based LTE Cognitive Radio Testbed
    A. Kabbani, A. R. Ali, H. Cao, A. B. Güven, Y. Gao, S. Peethala, and T. Kaiser, "Implementation Aspects of a DSP-Based LTE Cognitive Radio Testbed," Int. Conf. Cognitive Radio Oriented Wireless Networks (CROWNCOM), Qatar, April 2015.
  • An Enhanced Spectrum Sensing Algorithm with Maximum Ratio Combination of Spectral Correlation
    T. T. Nguyen, T. Kreul, and T. Kaiser, "An Enhanced Spectrum Sensing Algorithm with Maximum Ratio Combination of Spectral Correlation", EUSIPCO 2015, Nice, France, 31 Aug. - 4 Sept. 2015.
  • A Multi-Channel Spectrum Sensing Scheme with Filter Bank Realization for LTE Signals
    T. T. Nguyen, H. Cao, T. Kreul and T. Kaiser, "A Multi-Channel Spectrum Sensing Scheme with Filter Bank Realization for LTE Signals", 3rd IEEE Int. Workshop on Emerging Cognitive Radio Applications and Algorithms (in conjunction with IEEE WoWMoM 2015), Boston, MA, USA, 14-17 June 2015.
  • Experiments on Spectrum Sensing Algorithms of Pilot-Added OFDM Signals with a Cognitive LTE-A System
    T. T. Nguyen, A. Kabbani, S. Peethala, T. Kreul, T. Kaiser, "Experiments on Spectrum Sensing Algorithms of Pilot-Added OFDM Signals with a Cognitive LTE-A System", 2015 IEEE 20th Int. Workshop on Computer Aided Modelling and Design of Communication Links and Networks, Guildford, UK, 7-9 Sept. 2015.
  • Interference Alignment with Frequency Clustering for Efficient Resource Allocation in Cognitive Radio Networks
    M. El-Absi, M. Shaat, F. Bader, and T. Kaiser, "Interference Alignment with Frequency Clustering for Efficient Resource Allocation in Cognitive Radio Networks," IEEE Transactions on Wireless Communications, 2015
  • Experiments on multi-channel spectrum sensing with filter bank realization for cognitive LTE-A systems
    T. T. Nguyen, M. Hoffmann, T. Kreul, and T. Kaiser, "Experiments on multi-channel spectrum sensing with filter bank realization for cognitive LTE-A systems", Int. Conf. Advanced Technologies for Communications 2015, Ho Chi Minh City, Vietnam, 14-16 Oct. 2015.
  • Real-time Testbed for Validating Distributed Antenna Scenarios
    S. D. V. Peethala, T. Kreul, T. Kaiser, "Real-time Testbed for Validating Distributed Antenna Scenarios," 20th Int. ITG Workshop on Smart Antennas, Munich, Germany, 9-11 March 2016.
  • Cyclic prefix-based noise estimation with DVB-T input for spectrum sensing in cognitive radio
    D. Farahiyah, T. T. Nguyen, and T. Kaiser, "Cyclic prefix-based noise estimation with DVB-T input for spectrum sensing in cognitive radio," 3rd Int. Conf. Information Technology, Computer and Electrical Engineering, Semarang, Indonesia, 18-20 Oct. 2016.
  • Wideband Hybrid Analog-Digital Beamforming Massive MIMO Systems Based on Rotman Lens
    Y. Gao, M. Khaliel, T. Kaiser, "Wideband Hybrid Analog-Digital Beamforming Massive MIMO Systems Based on Rotman Lens," 15th IEEE Int. Conf. Communication Systems, Shenzhen, China, Dec. 14-16, 2016.
  • Massive MIMO Detection Based on Belief Propagation in Spatially Correlated Channels
    Y. Gao, H. Niu, T. Kaiser, "Massive MIMO Detection Based on Belief Propagation in Spatially Correlated Channels," 11th Int. ITG Conf. Systems, Communications and Coding 2017, Hamburg, Germany, Feb. 6-9, 2017.
  • Interference Alignment and Free-Space Optics Based Backhaul Networks
    A. Jendeya, M. El-Absi, N. Zarifeh, S. S. Ikki, T. Kaiser, "Interference Alignment and Free-Space Optics Based Backhaul Networks," 11th Int. ITG Conf. Systems, Communications and Coding 2017, Hamburg, Germany, Feb. 6-9, 2017.