Sidelobe Reduction in Cognitive Radio Systems Using Hybrid Technique
Orthogonal frequency division multiplexing (OFDM) is one of the best candidates for dynamic spectrum access due to its flexibility of spectrum shaping. However, the high sidelobes of the OFDM signal that result in high out-of-band radiation, introduce significant interference to the users operating in its vicinity. This problem becomes more critical in cognitive radio (CR) system that enables the secondary users (SUs) users to access the spectrum holes not used by the primary users (PUs) at that time. In this paper, we present a generalized OFDM framework that has a capability of describing any sidelobe suppression techniques, despite of whether one or a number of techniques are used. Based on that framework, we propose cancellation carrier (CC) technique in conjunction with the generalized sidelobe canceller (GSC) to reduce the out-of-band radiation in the region where the licensed users are operating. Simulation results show that the proposed technique can reduce the out-of-band radiation better when compared with the existing techniques found in the literature.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1128921Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 831
 B. Wang and K. J. R. Liu, “Advances in cognitive radio networks: A survey,” IEEE Journal of selected topics in signal processing, vol. 5, no. 1, pp. 5–23, 2011.
 A. Goldsmith, S. A. Jafar, I. Maric, and S. Srinivasa, “Breaking spectrum gridlock with cognitive radios: An information theoretic perspective,” Proceedings of the IEEE, vol. 97, no. 5, pp. 894–914, 2009.
 J. Mitola and G. Q. Maguire, “Cognitive radio: making software radios more personal,” IEEE personal communications, vol. 6, no. 4, pp. 13–18, 1999.
 J. A. C. Bingham, “Multicarrier modulation for data transmission: An idea whose time has come,” IEEE Communications magazine, vol. 28, no. 5, pp. 5–14, 1990.
 J. G. Proakis and M. Salehi, Salehi Digital Communications. New York, NY: McGraw-Hill, 2008.
 A. Sahin and H. Arslan, “Edge windowing for OFDM based systems,” Communications Letters, IEEE, vol. 15, no. 11, pp. 1208–1211, 2011.
 J. Luo, W. Keusgen, and A. Kortke, “Optimization of time domain windowing and guardband size for cellular OFDM systems,” in Vehicular Technology Conference, 2008. VTC 2008-Fall. IEEE 68th, 2008, pp. 1–5.
 D. Noguet, M. Gautier, and V. Berg, “Advances in opportunistic radio technologies for TVWS,” EURASIP Journal on Wireless Communications and Networking, vol. 2011, no. 1, pp. 1–12, 2011.
 S. Brandes, I. Cosovic, and M. Schnell, “Reduction of out-of-band radiation in OFDM systems by insertion of cancellation carriers,” IEEE communications letters, vol. 10, no. 6, pp. 420–422, 2006.
 S. Brandes, I. Cosovic, and M. Schnell, “Sidelobe suppression in OFDM systems by insertion of cancellation carriers,” in Vehicular Technology Conference, 2005. VTC-2005-Fall. 2005 IEEE 62nd, 2005, vol. 1, pp. 152–156.
 A. Elahi, I. M. Qureshi, F. Zaman, and F. Munir, “Reduction of out of band radiation in non-contiguous OFDM based cognitive radio system using heuristic techniques,” J. Inf. Sci. Eng, vol. 32, no. 2, pp. 349–364, 2016.
 A. Selim, I. Macaluso, and L. Doyle, “Efficient sidelobe suppression for OFDM systems using advanced cancellation carriers,” in Communications (ICC), 2013 IEEE International Conference on, 2013, pp. 4687–4692.
 A. Selim and L. Doyle, “Real-time sidelobe suppression for OFDM systems using advanced subcarrier weighting,” in Wireless Communications and Networking Conference (WCNC), 2013 IEEE, 2013, pp. 4043–4047.
 S. Pagadarai, R. Rajbanshi, A. M. Wyglinski, and G. J. Minden, “Sidelobe suppression for OFDM-based cognitive radios using constellation expansion,” in Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE, 2008, pp. 888–893.
 D. Li, X. Dai, and H. Zhang, “Sidelobe suppression in NC-OFDM systems using constellation adjustment,” Communications Letters, IEEE, vol. 13, no. 5, pp. 327–329, 2009.
 X. Zhou, G. Y. Li, and G. Sun, “Multiuser spectral precoding for OFDM-based cognitive radio systems,” IEEE Journal on Selected Areas in Communications, vol. 31, no. 3, pp. 345–352, 2013.
 R. Xu and M. Chen, “A precoding scheme for DFT-based OFDM to suppress sidelobes,” IEEE Communications Letters, vol. 13, no. 10, pp. 776–778, 2009.
 M. Ma, X. Huang, B. Jiao, and Y. J. Guo, “Optimal orthogonal precoding for power leakage suppression in DFT-based systems,” Communications, IEEE Transactions on, vol. 59, no. 3, pp. 844–853, 2011.
 A. Elahi, I. M. Qureshi, Z. U. Khan, and F. Zaman, “Sidelobe Reduction in Non-Contiguous OFDM-Based Cognitive Radio Systems Using a Generalized Sidelobe Canceller,” Applied Sciences, vol. 5, no. 4, pp. 894–909, 2015.
 A. Elahi, I. M. Qureshi, F. Zaman, F. Munir, and A. Umar, “Techniques for the suppression of sidelobes in a non‑contiguous orthogonal frequency division multiplexing framework,” Applied Informatics Springer Berlin Heidelberg, vol. 3, no. 1, p. 6, 2016.