Licensed Shared Access and Cognitive Radio
The  “Licensed Shared Access” (LSA) (a.k.a. “Authorised Shared Access” – ASA) paradigm, where incumbent operators may allow others to share their spectrum at specific times and places, according to an agreed set of rules. 

Key Facts :
  1. Shared use of spectrum based on radio cognition
  2. Implemented via individual authorisation scheme ensuring QoS
  3. Access rights can be granted on a temporary or long term basis

Research
Members Involved : M. C. Filippou, Sudip Biswas, K. Singh, Faheam Khan

Publications
  1. G. K. Papageorgiou,..., M. Pesavento, T. Ratnarajah,..., D. T. M. Slock, F. Khan and C. B. Papadias, "Advanced Dynamic Spectrum 5G Mobile Networks Employing Licensed Shared Access," IEEE Communications Magazine, pp. 27-27, July 2020.
  2. F. Liu, C. Masouros, A. Li, T. Ratnarajah, "Robust MIMO Beamforming for Cellular and Radar Coexistence," IEEE Wireless Communications Letters, Vol. 6, Issue 3, pp.374-377, April 2017.
  3. F. Liu, C. Masouros and L. Ang and T. Ratnarajah, "MIMO Radar and Cellular Coexistence: A Power-Efficient Approach Enabled by Interference Exploitation" IEEE Trans. on Signal Processing, in press.
  4. K. Singh, S. Biswas, T. Ratnarajah and F. H. Khan, "Transceiver Design and Power Allocation for Full-Duplex MIMO Communication Systems with Spectrum Sharing Radar," IEEE Trans. on Cognitive Communications and Networking, in press. 
  5. O. Y. Kolawole, S. Vuppala, M. Sellathurai, and T. Ratnarajah, "On the Performance of Cognitive Satellite-Terrestrial Networks," IEEE Trans. on Cognitive Communications and Networking, Vol. 3, Issue 4, pp. 668-683, Dec. 2017.  
  6. A. C. Cirik, S. Biswas, and T. Ratnarajah, "Robust Transceiver Design in Full-Duplex MIMO Cognitive Radios" IEEE Trans. on Vehicular Technology, Vol. 67, Issue 2, pp. 1313-1330, Feb. 2018.
  7. F. Liu, C. Masouros, A. Li and T. Ratnarajah, "Radar and Communication Coexistence Enabled by Interference Exploitation," In Proc. IEEE Global Communications Conference, Singapore, 4-8 Dec. 2017.
  8. M. C. Filippou, G. A. Ropokis, D. Gesbert, and T. Ratnarajah, "Joint Sensing and Reception Design of SIMO Hybrid Cognitive Radio Systems," IEEE Trans on Wireless Communications, Vol. 15, No. 9, pp 6321-6341, Sep. 2016.
  9. M. C. Filippou, P. D. Kerret, D. Gesbert, T. Ratnarajah, A. Pastore, G. A. Ropokis, "Coordinated Shared Spectrum Precoding with Distributed CSIT," IEEE Trans on Wireless Communications, Vol. 15, No. 8, pp. 5182-5192, Aug. 2016.​
  10. Y. He, J. Xue, T. Ratnarajah, M. Sellathurai, and F. Khan, "On the Performance of Cooperative Spectrum Sensing in Random Cognitive Radio Networks," IEEE SYSTEMS JOURNAL, in press.
  11. E. H. G. Yousif, T.Ratnarajah and M. Sellathurai, "A Frequency Domain Approach to Eigenvalue-Based Detection with Diversity Reception and Spectrum Estimation", IEEE Trans. on Signal Processing, IEEE Trans. on Signal Processing, Vol. 64, No. 1, pp.35-47, Jan. 2016.
  12. E. H. G. Yousif, T.Ratnarajah and M. Sellathurai, "Modeling and Performance Analysis of Multitaper Detection Using Phase-Type Distributions over MIMO Fading Channels," IEEE Trans. on Signal Processing, Vol. 63, No. 22, pp.5882-5896, Nov. 2015.
  13. Y. He, T. Ratnarajah, E H.G. Yousif, J. Xue, M. Sellathurai, "Performance Analysis of Multi-antenna GLRT-Based Spectrum Sensing for Cognitive Radio," Signal Processing, in press, Available online 24 October 2015.
  14. L. Li, F. A. Khan, M. Pesavento, T. Ratnarajah, "Sequential Search Based Power Allocation and Beamforming Design in Overlay Cognitive Radio Networks," Signal Processing, Vol. 97, pp. 221-231, April 2014.
  15. A. Kortun, T. Ratnarajah, M. Sellathurai, Y-C Liang and Y. Zeng, "On the Eigenvalue Based Spectrum Sensing and Secondary User Throughput," IEEE Trans. on Vehicular Technology, Vol. 60, Issue 3, pp. 1480-1486, March 2014.
  16. T. Ratnarajah, C. Masouros, F. Khan, and M. Sellathurai, "Analytical Derivation of Multiuser Diversity Gains with Opportunistic Spectrum Sharing in CR Systems," IEEE Trans. on Communications, Vol. 61, No. 7, pp. 2664-2667, July 2013.
  17. H. Du and T. Ratnarajah, "Robust Utility Maximization and Admission Control for MIMO Cognitive Radio Network," IEEE Trans. on Vehicular Technology, Vol. 62, No. 4, pp. 1707-1718, May 2013.
  18. A. Kortun, M. Sellathurai, T. Ratnarajah, and C. Zhong, "Distribution of the Ratio of the Largest Eigenvalue to the Trace of Complex Wishart Matrices," IEEE Trans. on Signal Processing, Vol. 60, No 10, pp. 5527-5532, Oct. 2012.
  19. C. Masouros and T. Rantarajah, "Interference as a Source of Green Signal Power in Cognitive Relay Assisted Co-Existing MIMO Wireless Transmissions," IEEE Trans. Communications, Vol. 60, pp. 525-536, Feb. 2012.
  20. H. Du, T. Ratnarajah, M. Pesavento, C. B. Papadias, "Joint Transceiver Beamforming in MIMO Cognitive Radio Network via Second-Order Cone Programming," IEEE Trans. on Signal Processing, Vol. 60, pp. 781-792, Feb. 2012.
  21. C. Zhong and T. Ratnarajah, "Performance of User Selection in Cognitive Broadcast Channels," IEEE Trans. on Communications, Vol. 60, No. 12, pp. 3529-3534, Dec 2012.
  22. F. Khan, C. Masouros and T. Ratnarajah, "Interference Driven Linear Precoding in Multiuser MISO Downlink Cognitive Radio Network," IEEE Trans. On Vehicular Technology, Vol. 61, pp. 2531-2543, June 2012.
  23. A. Kortun, T. Ratnarajah, M. Sellathurai, C. Zhong and C. Papadias, "On the Performance of Eigenvalue-based Cooperative Spectrum Sensing for Cognitive Radio," IEEE Journal of Selected Topics in Signal Processing, Vol. 5, No. 1, pp. 49-55, Feb. 2011.