Unified Theory of QSTBCs for Four Transmit Antennas

This work establishes a unified theoretical framework for Quadrature Space-Time Block Codes (QSTBCs) with four transmit antennas and one or more receive antennas. The research comprises two main components: Part I investigates QSTBC transmission without channel knowledge at the transmitter, while Part II explores transmission with partial Channel State Information (CSI). For both scenarios, we analyze QSTBC performance using Maximum Likelihood receivers and low-complexity Linear Zero-Forcing receivers over spatially correlated/uncorrelated frequency-flat MIMO channels. Spatial correlation is modeled using the Kronecker correlation model, and practical validation is performed through indoor measured channels.