Reducing MIMO detection complexity via hierarchical modulation /

Uğur, Yiğit
This work considers multiple-inputmultiple-output (MIMO) communication systems using hierarchical modulation. A disadvantage of the maximum-likelihood (ML) MIMO detector is that its computational complexity increases exponentially with the number of transmit antennas. To reduce complexity, we propose a hierarchical modulation scheme to be used in MIMO transmission where base and enhancement layers are incorporated. In the proposed receiver, the base layer is detected first with a minimum mean square error (MMSE) detector which is followed by ML detection of the enhancement layer. Our results indicate that performance close to ML detection can be achieved with the proposed scheme, yet at a significantly lower complexity.


Chaotic demodulation under interference
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Chaotically modulated signals are used in various engineering areas such as communication systems, signal processing applications, automatic control systems. Because chaotically modulated signal sequences are broadband and noise-like signals, they are used to carry binary signals especially in secure communication systems. In this thesis, a target tracking problem under interference at chaotic communication systems is investigated. Simulating the chaotic communication system, noise-like signal sequences are...
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In this work we study the effect of hierarchical modulation on completion time minimization in wireless broadcast channels. Time needed to transmit all bits intended for a particular user is defined as its completion time. In this work we investigate minimizing the maximum completion time over all users in a broadcast channel using hierarchical modulation. We compare time division, opportunistic scheduling, and three different adaptive modulation schemes: rate adaptive hierarchical modulation assisted trans...
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Erkek, Eser; Demir, Şimşek; Department of Electrical and Electronics Engineering (2009)
Microwave and millimeter-wave phase shifters are one of the most important structures of the antenna series that are used in communication and radar applications. They are used to form the main beam of the electronically scanned phase array antennas and generate the appropriate phase values for the antenna elements design while providing electronic beam steering. In this thesis, S-band hybrid 4 bit phase shifter of 22.5º phase resolution is designed, simulated, fabricated and measured. Bits are separately d...
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Yalcyn, Ahmet Zahid; Yüksel Turgut, Ayşe Melda (2014-07-01)
In communication systems, hierarchical modulation is used to increase system robustness and to send different information flows simultaneously. However, when used in cooperative communication systems, hierarchical modulation is prone to error propagation, which is the most important problem that prevents the achievement of full diversity gains. Depending on the signal-to-noise ratio between the source and the relay, threshold digital relaying can be used to mitigate error propagation. Mitigating error propa...
Noise reduction in time-frequency domain
Kalyoncu, Özden; SÜnver, Zafer; Department of Electrical and Electronics Engineering (2007)
In this thesis work, time-frequency filtering of nonstationary signals in noise using Wigner-Ville Distribution is investigated. Continuous-time, discrete-time and discrete Wigner Ville Distribution definitions, their relations, and properties are given. Time-Frequency Peak Filtering Method is presented. The effects of different parameters on the performance of the method are investigated, and the results are presented. Time-Varying Wiener Filter is presented. Using simulations it is shown that the performa...
Citation Formats
Y. Uğur, “Reducing MIMO detection complexity via hierarchical modulation /,” M.S. - Master of Science, Middle East Technical University, 2014.