Physical layers of communication systems using Filter Bank Multicarrier (FBMC) as a modulation scheme provide low out-of-band leakage but suffer from the large Peak-to-Average Power Ratio (PAPR) of the transmitted signal. Two special FBMC schemes are investigated in this paper: the Orthogonal Frequency Division Multiplexing (OFDM) and the Staggered Multitone (SMT). To reduce the PAPR of the signal, time domain clipping is applied in both schemes. If the clipping is not compensated, the system performance is severely affected. To avoid this degradation, an iterative noise cancelation technique, Bussgang Noise Cancelation (BNC), is applied in the receiver. It is shown that clipping can be a good means for reducing the PAPR, especially for the SMT scheme. A novel modified BNC receiver is presented for SMT. It is shown how this technique can be implemented in real-life applications where special requirements must be met regarding the spectral characteristics of the transmitted signal. 1. Introduction In wireless communications the frequency spectrum is an essential resource. As the unlicensed spectrum is used by an increasing number of devices, the possibility of communication collision is increasing. To avoid this collision, two solutions are possible: extending the frequency limits higher to unused frequency bands at the upper end of the spectrum or reaggregating the densely used licensed frequency bands. Both ideas have disadvantages: the use of higher frequencies requires expensive specially designed analog devices; the reuse of the spectrum calls for complex, intelligent, and adaptive systems. In this paper the focus is on the reuse of the spectrum with multicarrier modulations tailored for spectrally efficient applications. Future applications operating in the licensed bands, for example, cognitive radios, favor spectrally efficient FBMC schemes with low out-of-band leakage, minimizing harmful interference between devices using adjacent channels. In this paper two subclasses of FBMC are investigated, both allowing the use of a complex modulation alphabet: OFDM and SMT. Both of these schemes provide relatively low out-of-band leakage. Today OFDM [1] is the de-facto standard technique for high-speed wireless data transmission. Using OFDM, low-complexity modulation and demodulation can be performed by the “Inverse Fast Fourier Transform (IFFT)” and the Fast Fourier Transform (FFT), respectively. With Cyclic Prefix (CP), channel equalization can be efficiently implemented in the frequency domain. This scheme also has some drawbacks. As the PAPR of the
References
[1]
A. R. S. Bahai, B. R. Saltzberg, and M. Ergen, Multi Carrier Digital Communications: Theory and Applications of OFDM, Springer, 2004.
[2]
J. Gazda, P. Drotár, D. Kocur, P. Galajda, and R. Blicha, “Joint evaluation of nonlinear distortion effects and signal metrics in OFDM based transmission systems,” Acta Electrotechnica et Informatica, vol. 9, no. 4, pp. 55–60, 2009.
[3]
S. H. Han and J. H. Lee, “An overview of peak-to-average power ratio reduction techniques for multicarrier transmission,” IEEE Wireless Communications, vol. 12, no. 2, pp. 56–65, 2005.
[4]
P. Foomooljareon and W. Fernando, “PAPR reduction in OFDM systems,” Thammasat International Journal of Science and Technology, vol. 7, no. 3, 2002.
[5]
X. Li and L. J. Cimini, “Effects of clipping and filtering on the performance of OFDM,” IEEE Communications Letters, vol. 2, no. 5, pp. 131–133, 1998.
[6]
A. E. Jones, T. A. Wilkinson, and S. K. Barton, “Block coding scheme for reduction of peak to mean envelope power ratio of multicarrier transmission schemes,” Electronics Letters, vol. 30, no. 25, pp. 2098–2099, 1994.
[7]
A. D. S. Jayalath and C. Tellambura, “The use of interleaving to reduce the peak to average power ratio of an OFDM signal,” in Proceedings of the IEEE Global Telecommunication Conference (GLOBECOM ’00), vol. 1, pp. 82–86, 2000.
[8]
S. H. Müller and J. B. Huber, “OFDM with reduced peak-to-average power ratio by optimum combination of partial transmit sequences,” Electronics Letters, vol. 33, no. 5, pp. 368–369, 1997.
[9]
A. Mobasher and A. K. Khandani, “Integer-based constellation-shaping method for PAPR reduction in OFDM systems,” IEEE Transactions on Communications, vol. 54, no. 1, pp. 119–127, 2006.
[10]
S.-E. Park, Y. Sung-Ryul, J. Y. Kim, D. S. Park, and P. Y. Joo, “Tone reservation method for PAPR reduction scheme,” Tech. Rep. IEEE 802.16e Task Group, IEEE 802.16e-03n60, 2003.
[11]
S. H. Han, J. M. Cioffi, and J. H. Lee, “Tone injection with hexagonal constellation for peak-to-average power ratio reduction in OFDM,” IEEE Communications Letters, vol. 10, no. 9, pp. 646–648, 2006.
[12]
B. S. Krongold and D. L. Jones, “PAR reduction in OFDM via active constellation extension,” IEEE Transactions on Broadcasting, vol. 49, no. 3, pp. 258–268, 2003.
[13]
B. Farhang-Boroujeny and C. H. Yuen, “Cosine modulated and offset QAM filter bank multicarrier techniques: a continuous-time prospect,” Eurasip Journal on Advances in Signal Processing, vol. 2010, Article ID 165654, 2010.
[14]
F. Schaich, “Filterbank based multi carrier transmission (FBMC)—evolving OFDM: FBMC in the context of WiMAX,” in Proceedings of the European Wireless Conference (EW '10), pp. 1051–1058, April 2010.
[15]
P. Siohan, C. Siclet, and N. Lacaille, “Analysis and design of OFDM/OQAM systems based on filterbank theory,” IEEE Transactions on Signal Processing, vol. 50, no. 5, pp. 1170–1183, 2002.
[16]
M. Colas, G. Gelle, and D. Declercq, “Analysis of iterative receivers for clipped COFDM signaling based on soft Turbo-DAR,” in Proceedings of the 1st International Symposium on Wireless Communication Systems (ISWCS '04), pp. 110–114, September 2004.
[17]
H. Chen and A. Haimovich, “An iterative method to restore the performance of clipped and filtered OFDM signals,” in Proceedings of the International Conference on Communications (ICC '03), pp. 3438–3442, May 2003.
[18]
R. Djardin, M. Colas, and G. Gelle, “Comparison of iterative receivers mitigating the clipping noise of OFDM based system,” in Proceedings of the European Wireless Conference, 2007.
[19]
Z. Kollár, M. Grossmann, and R. Thom？, “Convergence analysis of BNC turbo detection for clipped OFDM signalling,” in Proceedings of the 13th International OFDM-Workshop (InOWo’08), pp. 241–245, Hamburg, Germany, 2008.
[20]
D. S. Waldhauser and J. A. Nossek, “Multicarrier systems and filter banks,” Advances in Radio Science, vol. 4, pp. 165–169, 2006.
[21]
Z. Kollár, G. Péceli, and P. Horváth, “Iterative decision feedback equalization for FBMC systems,” in Proceedings of the 1st International Conference on Advances in Cognitive Radio (COCORA '11), Budapest, Hungary, 2011.
[22]
T. Ihalainen, T. H. Stitz, and M. Renfors, “Efficient per-carrier channel equalizer for filter bank based multicarrier systems,” in Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS '05), pp. 3175–3178, jpn, May 2005.
[23]
Z. Kollár and P. Horváth, “Modulation schemes for cognitive radio in white spaces,” Radioengineering, vol. 19, no. 4, pp. 511–517, 2010.
[24]
L. Baltar, D. S. Waldhauser, and J. A. Nossek, “Out-of-band radiation in multicarrier systems: a comparison,” Multi-Carrier Spread Spectrum, vol. 1, pp. 107–116, 2007.
[25]
H. E. Rowe, “Memoryless non-linearities with gaussian inputs: elementary results,” The Bell System Technical Journal, vol. 61, no. 7, pp. 1519–1525, 1982.
[26]
S. Ten Brink, “Designing iterative decoding schemes with the extrinsic information transfer chart,” AEU-Archiv fur Elektronik und Ubertragungstechnik, vol. 54, no. 6, pp. 389–398, 2000.
[27]
S. ten Brink, J. Speidel, and R. H. Yan, “Iterative demapping and decoding for multilevel modulation,” in Proceedings of the Global Telecommunications Conference, (GLOBECOM '98), pp. 579–584, November 1998.
[28]
L. R. Bahl, J. Cocke, F. Jelinek, and J. Raviv, “Optimal decoding of linear codes for minimizing symbol error rate,” IEEE Transactions on Information Theory, vol. IT-20, no. 2, pp. 284–287, 1974.
[29]
“Phydyas project: documents D2.1 and D3.1,” 2008, http://www.ict-phydyas.org/.
[30]
P. Sharma, S. Verma, and A. Basu, “Modified clipping and filtering technique for peak-to-average power ratio reduction of OFDM signals used in WLAN,” International Journal of Engineering Science and Technology, vol. 2, no. 10, pp. 5337–5343, 2010.
[31]
M. Bellanger, “Physical layer for future broadband radio systems,” in Proceedings of the IEEE Radio and Wireless Symposium (RWW '10), pp. 436–439, January 2010.
[32]
E. Sofer and G. Chouinard, “WRAN channel modeling,” IEEE 802.22-05/0055r7, 2005.
[33]
G. Bauch, Turbo-Entzerrung, und Sendeantennen Diversity mit Space-Time-Codes im Mobilfunk, VDI Verlag GmbH, Düsseldorf, Germany, 2001.
