Performance Analysis and Mitigation Techniques for I/Q-Corrupted OFDM Systems

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2016-01-15
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Author
Date
2015
Department
Tietoliikenne- ja tietoverkkotekniikan laitos
Department of Communications and Networking
Major/Subject
Mcode
Degree programme
Language
en
Pages
82 + app. 62
Series
Aalto University publication series DOCTORAL DISSERTATIONS, 219/2015
Abstract
Orthogonal Frequency Division Multiplexing (OFDM) has become a widely adopted modulation technique in modern communications systems due to its multipath resilience and low implementation complexity. The direct conversion architecture is a popular candidate for low-cost, low-power, fully integrated transceiver designs. One of the inevitable problems associated with analog signal processing in direct conversion involves the mismatches in the gain and phases of In-phase (I) and Quadrature-phase (Q) branches. Ideally, the I and Q branches of the quadrature mixer will have perfectly matched gains and are orthogonal in phase. Due to imperfect implementation of the electronics, so called I/Q imbalance emerges and creates interference between subcarriers which are symmetrically apart from the central subcarrier. With practical imbalance levels, basic transceivers fail to maintain the sufficient image rejection, which in turn can cause interference with the desired transmission. Such an I/Q distortion degrades the systems performance if left uncompensated. Moreover, the coexistence of I/Q imbalance and other analog RF imperfections with digital baseband and higher layer functionalities such as multiantenna transmission and radio resource management, reduce the probability of successful transmission. Therefore, mitigation of I/Q imbalance is an essential substance in designing and implementing modern communications systems, while meeting required performance targets and quality of service. This thesis considers techniques to compensate and mitigate I/Q imbalance, when combined with channel estimation, multiantenna transmission, transmission power control, adaptive modulation and multiuser scheduling. The awareness of the quantitative relationship between transceiver parameters and system parameters is crucial in designing and dimensioning of modern communications systems. For this purpose, analytical models to evaluate the performance of an I/Q distorted system are considered.
Description
Supervising professor
Tirkkonen, Olav, Prof., Aalto University, Department of Communications and Networking, Finland
Keywords
I/Q imbalance, performance analysis, channel estimation, MIMO, precoding, link adaptation, D2D communication
Other note
Parts
  • [Publication 1]: U. Oruthota, O. Tirkkonen. SER/BER expression for M-QAM OFDM systems with imperfect channel estimation and I/Q imbalance. EURASIP Journal onWireless Communications and Networking, 2012:303, September 2012.
    DOI: 10.1186/1687-1499-2012-303 View at publisher
  • [Publication 2]: U. Oruthota, O. Tirkkonen, and N. Y. Ermolova. Analysis of spacefrequency coded OFDM with I/Q imbalance. In Proceedings of the International Congress on Ultra Modern Telecommunications and Control Systems, ICUMT, pp. 275-280, October 2010.
  • [Publication 3]: U. Oruthota, O. Tirkkonen. I/Q imbalance compensation in precoded MIMO-OFDMA systems. In Proceedings of the International Symposium on Wireless Personal Multimedia Communications, WPMC, pp. 291-295, September 2012.
  • [Publication 4]: U. Oruthota, O. Tirkkonen. Link adaptation of precoded MIMO-OFDMA system with I/Q interference. IEEE Transactions on Communications, vol. 63, no. 3, pp. 780-790, March 2015.
    DOI: 10.1109/TCOMM.2015.2391180 View at publisher
  • [Publication 5]: U. Oruthota, O. Tirkkonen. I/Q interference in device-to-device underlay communication with uplink power control. In Proceedings of the 81st IEEE Vehicular Technology Conference, VTC Spring, pp. 1-5, May 2015.
    DOI: 10.1109/VTCSpring.2015.7145866 View at publisher
Citation
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https://urn.fi/URN:ISBN:978-952-60-6596-0
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[diss] Sähkötekniikan korkeakoulu / ELEC