Polarization diversity in channel modeling for mimo systems

Söker, Burak
In a multiple-input multiple-output (MIMO) system, inter-antenna distances can be made large and uncorrelated signals can be transmitted and received when there is sufficient space at the transmitter (TX) and receiver (RX). When the antennas are closely spaced, diversity advantage is lost and communication performance degrades. In this case, polarization diversity can be used in order to decrease the correlation and improve communication performance. A detailed channel model, which includes both cross polar discrimination (XPD) and correlation coefficient, is used in this study. Transmitter is assumed to have enough space and correlation is considered for the receiver only. Received signal correlation coefficients are generated from a realistic random 3-D model including antenna polarization orientations, XPD, azimuth and elevation angles of direction-of-arrival. In this study, channels with and without correlation are considered. Polarization diversity in a 2×2 MIMO communication system is investigated for Alamouti (AL) and spatial multiplexing (SM) transmission schemes considering both BER performance and channel capacity. In addition, effects of the number of antennas on SM BER and capacity are investigated for 3×3 and 4×4 MIMO systems. BER and capacity performance of single polarization and polarization diversity are compared for constant and distance dependent random channel parameters. The relative performance of single polarization and polarization diversity system depends significantly on the channel characteristics. It is shown that polarization diversity results better BER and capacity compared to single polarization especially when there is not enough space at the receiver. Therefore, polarization diversity can be used in MIMO systems with limited antenna space, in order to improve communication performance.


Fast simulation and modeling of scattering from targets in MIMO imaging systems
Gül , Yunus Emre; Alatan, Lale; Department of Electrical and Electronics Engineering (2022-5-11)
The forward model analysis in a multiple input multiple output (MIMO) system requires the computation of the signals received by receiver antennas when various targets are illuminated by a transmitter antenna. The full wave analysis of such systems provides accurate results with high computational cost. Fast analysis of the system can be achieved by simple models based on several approximations which limits the accuracy. In this thesis, a modeling technique that provides better accuracy compared to simple m...
Broadband loaded dipole antenna design by genetic algorithm optimization
Asan, Bahri; Koç, Seyit Sencer; Department of Electrical and Electronics Engineering (2014)
It is well known that standard dipole antenna is not convenient to be used in broadband wireless communication applications because of its narrow frequency bandwidth. To broaden the bandwidth of a dipole, lumped loading is the generally applied method. Positive effects of resistive, capacitive and inductive loading are discussed and proved for a pretty long time. This thesis investigates broadband lumped loaded dipole antenna design procedure by using genetic algorithm optimization techniques. First, unload...
Design and implementation of VHF-UHF antenna with non-foster matching circuit
Aşcı, Cihan; Aydın Çivi, Hatice Özlem; Department of Electrical and Electronics Engineering (2018)
Matching networks are widely used in the antenna transmitter and receiver applications and thus they are an essential part of the RF system. Conventional passive matching networks are very broadly used for matching an antenna for a narrow band of frequencies; however, achieving a broad bandwidth characteristics for electrically–small antennas (ESAs) is not possible with the use of passive matching circuits. ESAs possess a large input reactance and the electrical size of the antenna element is very small com...
Milimeter wave microstrip launchers and antenna arrays
Akgün, Erdem; Hızal, Altunkan; Department of Electrical and Electronics Engineering (2006)
Coaxial-to-microstrip launcher and microstrip patch array antenna are designed to work at center frequency of 36.85 GHz with a bandwidth higher than 300 MHz. The antenna array design also includes the feeding network distributing the power to each antenna element. The design parameters are defined on this report and optimized by using an Electromagnetic Simulation software program. In order to verify the theoretical results, microstrip patch array antenna is produced as a prototype. Measurements of antenna ...
Interference suppression capability of faster than symbol rate sampling and frequency domain oversampling
Balevi, Eren; Yılmaz, Ali Özgür; Department of Electrical and Electronics Engineering (2016)
Detection of symbols in the presence of many interference sources is a difficult task in wireless channels. It is obligatory to reduce the interference for reliable communication. In this dissertation, minimum mean square error (MMSE) detection is investigated to suppress interference. Faster Than Symbol Rate (FTSR) sampling and Frequency Domain Oversampling (FDO) methods are proposed to enhance the interference suppression level of MMSE detection for both single user and multiuser communication. The aim of...
Citation Formats
B. Söker, “Polarization diversity in channel modeling for mimo systems,” M.S. - Master of Science, Middle East Technical University, 2013.