Capacity improvement in MIMO-OFDM WLAN systems using compact multimode antenna arrays and antenna selection

The recent developments in wireless communication systems in indoor environments requires high data rate and high transmission quality especially for multimedia applications in WLAN (Wireless Local Area Network) systems. In the next generation communication systems, the spectral efficiency and transmission quality can be vastly enhanced by using compact-multiple-antennas with low correlation ports at both the transmitter and the receiver side for MIMO communication. In this thesis, the performance analysis in terms of ergodic spectral efficiency and data rate as well as compactness gain for both compact space-multimode stacked circular microstrip patch antenna arrays (SM-SCP-ULA) and space-multimode-polarization stacked circular microstrip patch antenna arrays (SMP-SCP-ULA) which are used for MIMO SM (Spatial Multiplexing) communication in OFDM WLAN systems conforming to IEEE802.11n Standard is presented by using linear MIMO detectors comperatively with respect to dipole atenna arrays (DP-ULA) and dominant mode circular patch antenna arrays (CP-ULA). Multiple antennas and also MIMO can improve the system capacity and reiability of radio communication, however the multiple RF chains associated with multiple antennas are costly in terms of hardware, computational complexity and size. Antenna selection is a low-cost solution to reduce this problem. In this thesis, we propose capacity-maximization-based joint transmit/receive antenna selection in IEEE 802.11n MIMO-OFDM WLANs over spatially-correlated Ricean fading channels composed of using Space-Multimode-Polarization Diversity Stacked Circular Multimode Microstrip Patch Antenna Arrays (SMP-SCP-ULA). Selection algorithms are flexible Two-Step Selection Algorithm (TSSA) at the receiver and Variable Per-Tone Selection Algorithm (VAS-PS) at the transmitter. Using capacity-maximization based antenna selection in conjunction with higher-order modal SMP-SCP-ULA provides an additional performance improvement in terms ergodic spectral efficiency and reduces the need for multiple radio frequency (RF) chains.