Downlink transmission techniques for multi user multi input multi output wireless communications

Coşkun, Adem
Multi-user MIMO (MIMO-MU) communication techniques make use of available channel state information at the transmitter to mitigate the inter-user interference. The goal of these techniques is to provide the least interference at the mobile stations by applying a precoding operation. In this thesis a comparison of available techniques in the literature such as Channel Decomposition, SINR Balancing, Joint-MMSE optimization is presented. Novel techniques for the MIMO multi-user downlink communication systems, where a single stream is transmitted to each user are proposed. The proposed methods, different from the other methods in the literature, use a simple receiver to combat the interference. It has been shown that MRC based receivers are as good as more complicated joint MMSE receivers.


Reliable real-time video communication in wireless sensor networks
Ayran, Orhan; Akan, Özgür Barış; Department of Electrical and Electronics Engineering (2007)
Many wireless sensor network (WSN) applications require efficient multimedia communication capabilities. However, the existing communication protocols in the literature mainly aim to achieve energy efficiency and reliability objectives and do not address the multimedia communication challenges in WSN. In this thesis, comprehensive performance evaluation of the existing transport protocols is performed and it has been shown that the existing proposals achieve very poor performance in terms of large set of me...
Implementation of a digital signal synthesizer with high spurious free dynamic range
Kılıç, Argun; Yılmaz, Ali Özgür; Department of Electrical and Electronics Engineering (2006)
Today’s analog modulators and upconverters are inadequate to synthesize and modulate signals with high ‘Spurious Free Dynamic Range’ (SFDR). Thus, the main objective of this thesis is to design and implement a ‘Digital Signal Synthesizer’ (DSS) that is capable of synthesizing signals between 50-100 MHz with 60dB SFDR and to modulate them variable symbol rates and modulation techniques with very high phase/frequency resolution and switching speed while keeping the amplitude modulation occurring during a modu...
A new approach for the assessment of hf channel availability under ionospheric disturbances
Sarı, Murat Özgür; Tulunay, Ersin; Department of Electrical and Electronics Engineering (2006)
High Frequency (3-30 MHz) (HF) Ionospheric Channel is used for military, civilian and amateur communications. By using Ionosphere, communication for distances beyond the line of sight is achieved. The main advantage of this type of communication is that it does not to require a satellite to communicate with a point beyond the line of sight. Actually the Ionosphere is used instead of a satellite. To use Ionosphere but not a satellite means independent communication for a country. The disadvantage of HF Ionos...
Electronically tunable microwave bandstop filter design and implementation
Oruç, Sacid; Yıldırım, Nevzat; Department of Electrical and Electronics Engineering (2010)
In modern broadband microwave applications, receivers are very sensitive to interference signals which can come from the system itself or from hostile emitters. Electronically tunable bandstop filters can be used to eliminate these interference signals with adaptation to changing frequency conditions. In this thesis, electronically tunable bandstop filter design techniques are investigated for microwave frequencies. The aim is to find filter topologies which allow narrowband bandstop or ‘notch’ filter desig...
Comparison of the intercarrier interference cancellation methods in OFDM systems
Etiler, Burkay; Tuncer, Temel Engin; Department of Electrical and Electronics Engineering (2007)
In OFDM systems carrier frequency offset is observed due to Doppler shift and transmitter-receiver frequency mismatches. This offset induces ICI (Intercarrier Interference). In this thesis, repeated data methods and pilot-aided carrier frequency offset(CFO) estimation methods and windowing techniques are used to mitigate the frequency offset problem and a performance comparison is made between these ICI cancellation techniques. Repeated data methods use only half of the bandwidth for information transmissio...
Citation Formats
A. Coşkun, “Downlink transmission techniques for multi user multi input multi output wireless communications,” M.S. - Master of Science, Middle East Technical University, 2007.