Dissertation in the field of Communications Engineering, Udesh Oruthota
The title of thesis is Performance analysis and mitigation techniques for I/Q-corrupted OFDM Systems
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Orthogonal Frequency Division Multiplexing (OFDM) has become a widely adopted modulation technique in modern communications systems. The direct conversion architecture is a popular candidate for low-cost, low-power, fully integrated transceiver designs. Due to the finite tolerance of practical electronics, 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. So-called I/Q imbalance 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. The coexistence of I/Q imbalance and other analog RF imperfections with digital baseband and higher layer functionalities such as multi-antenna transmission and radio resource management, reduce the probability of successful transmission further. This work considers techniques to compensate and mitigate I/Q imbalance which is an essential substance in designing and implementing modern communications systems, while meeting required performance targets and quality of service.
Opponent: Professor Tommy Svensson, Chalmers University of Technology, Göteborg, Sweden
Supervisor: Professor Olav Tirkkonen, Aalto University School of Electrical Engineering, Department of Communications and Networking
Contact information:
Udesh Oruthota
udesh.oruthota@aalto.fi