Description
Date depot: 1 janvier 1900
Titre: BER and Spectral Efficiency analysis of Filter Bank based Multicarrier systems (FBMC) with Non Linear Power Amplifiers
Directeur de thèse:
Daniel ROVIRAS (CEDRIC)
Domaine scientifique: Sciences et technologies de l'information et de la communication
Thématique CNRS : Non defini
Resumé:
OFDM has been chosen for 4G future systems (LTE advance, 802.16). In a synchronized system orthogonality within subcarriers is achieved by using Cyclic Prefix (CP). One drawback of OFDM signals is the very high Peak to Average Power Ratio (PAPR) and the impairments when using Non Linear (NL) Power Amplifiers (PA). In LTE-A systems, the uplink uses SC-OFDM in order to limit the effect of the mobile terminal NL PA. Another drawback of OFM is the high sensitivity to time asynchronism within users. When time offset is higher than the CP, subcarriers are no longer orthogonal, yielding a severe performance loss.
Non synchronized users can be found in contexts such as Cognitive Radio where primary and secondary users are operating on a non-synchronized base. In non-licensed bands (Ad Hoc system), users are also non-synchronised. In such context, OFDMA will suffer from asynchronism.
In order to overcome this drawback, new multicarrier modulations have been introduced, specially Filter Bank based Multicarrier systems (FBMC) [1-4]. One great advantage of FBMC modulations is their good performance in a non-synchronized system. For Ad Hoc or CR systems this property is of great interest. This good performance in non-synchronized Rx/Tx is related to the frequency response of the pulse shaping filter of FBMC. Even with a total de-synchronization, a given subcarrier interfere only the two direct adjacent ones while OFDM interfere a large amount of adjacent subcarriers [5]. As long as the power amplifier is linear this property holds. When the PA is non-linear there will be a spectrum broadening and the advantage of FBMC compared to OFDM will be smaller: an FBMC subcarrier will interfere with more than the two direct adjacent subcarriers depending on the PAPR [6].
Objectives of the PhD:
The main objectives of the work will be:
• Performance analysis (BER, capacity) of FBMC with NL PA,
• Single Carrier FBMC,
• PAPR reduction techniques for FBMC.
Performance analysis:
Studies have been conducted for OFDM with NL PA [7] or for FBMC with asynchronism [8]. Performances of OFDM/FBMC systems in presence of de-synchronization and of a NL PA have not been investigated in literature. The objective of this part will be the theoretical study of performances in terms of BER and spectral efficiency of FBMC systems with non linear amplifiers and timing offsets.
Single carrier FBMC:
Single carrier OFDM has proved its ability to reach a lower PAPR. The objective of this part will be to study an equivalent technique applied to FBMC. Indeed, only few results are available on literature about this topic [9].
PAPR reduction techniques for FBMC:
Another aspect will be the PAPR reduction for FBMC systems. Classical PAPR reduction methods suited for OFDM [10] will be transposed to FBMC. Specific PAPR reduction methods for FBMC must be studied.
The thesis will be supervised by Daniel ROVIRAS and Hmaied SHAIEK in laboratory CEDRIC/CNAM.
REFERENCES:
[1] M.Bellanger, “Filter banks and OFDM/OQAM for high throughput wireless LAN,” 3rd International Symposium on Communications, Control and Signal Processing, 2008.ISCCSP 2008, pp 758 – 761,Malta, Mar 2008.
[2] M. G. Bellanger, ”Specification and design of a prototype filter for filter bank based multicarrier transmission,” in Proc. IEEE Int. Conf.
Acoustics, Speech, and Signal Processing, pp. 2417–2420, Salt Lake City, USA, May 2001.
[3] P. Siohan, C. Siclet and N. Lacaille, “Analysis and Design of OFDM/OQAM Systems Based on Filter bank Theory,” IEEE Trans. on Signal Proc., vol. 50, no. 5, pp. 1170-1183, May 2002.
[4] H.Boelcskei, “Orthogonal frequency division multiplexing based on offset QAM,” in Advances in Gabor analysis. Birkhuser, 2003.
[5] Haijian ZHANG, Didier Le Ruyet, Daniel Roviras, Yahia MEDJAHDI and Hong Sun, 'Spectral Efficiency Comparison of OFDM /FBMC for Uplink Cognitive Radio Networks,' Journal on Advances in Signal Processing, special issue : 'Filter Banks for Next Generation Multicarrier Wireless Communications', vol. 2010, Article ID 621808, 14 pages, 2010.
[6] M.Khodjet, C. Saber, D. Roviras, Y. Medjahdi, “Multicarrier interference evaluation with jointly non-linear amplification and timing errors”, VTC 2011 spring, May 2011, Budapest, Hungary
[7] Jian Qi and Sonia Aïssa, “Analysis and Compensation of Power Amplifier Nonlinearity in MIMO Transmit Diversity Systems”, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 59, NO. 6, JULY 2010 2921
[8] Yahia Medjahdi, Michel Terré, Didier Le Ruyet, Daniel Roviras, Ali Dziri, 'Performance Analysis in the Downlink of Asynchronous OFDM/FBMC based Multi-cellular Networks', IEEE trans. on Wireless Communications 2011, Page(s): 2630 - 2639
[9] Chung Him Yuen; Amini, P.; Farhang-Boroujeny, B., “Single carrier frequency division multiple access (SC-FDMA) for filter bank multicarrier communication systems”, Cognitive Radio Oriented Wireless Networks & Communications (CROWNCOM), 2010, Pages 1-5
[10] Tao Jiang and Y
Doctorant.e: Bouhadda Hanen