Exploiting diversity across space, time and frequency for high-rate communications

High data-rate and high reliability are two long-term objectives in digital communications theory and practice. This thesis discusses new approaches enabling communications systems to have both high spectral efficiency and high reliability without the need of having channel state information in the transmitters.; This thesis introduces the concept and structure of linear dispersion codes (LDC). This thesis proposes and analyzes a class of rectangular information lossless linear dispersion codes, which is termed uniform linear dispersion codes (U-LDC) and can be used for 2-dimensional channels with a number of advantages.; This thesis proposes and analyzes linear dispersion coded orthogonal frequency division multiplexing (LDC-OFDM) and linear dispersion coded single carrier modulation division multiplexing (LDC-SCM) for jointly exploiting time and frequency diversity in time varying frequency selective channels. Both LDC-OFDM and LDC-SCM may be applied to both wireline and wireless communications. Lower complexity approaches, double linear transformation coded OFDM and linear transformation coded SCM, are also proposed.; This thesis proposes and analyzes high-rate diversity approaches over space, time, and frequency dimensions for MIMO-OFDM systems. The proposed coded systems include linear dispersion space-time-frequency codes (LD-STFC), double linear dispersion space-time-frequency codes (DLD-STFC), and multiple-input multiple-output LDC-OFDM (MIMO-LDC-OFDM). This thesis introduces two diversity concepts for 3-dimensional codes: per dimension diversity order and per dimension symbol-wise diversity order; and provides a sufficient condition for DLD-STFC to achieve full symbol-wise diversity order in spite of the order of the two CDC stages. This thesis also investigates how much gain can be obtained using the combination of CDC and forward error correction (FEC) for STFC designs.; This thesis proposes coordinate-interleaving as a general principle for high-rate block-based space-time code design, i.e., space-time coordinate interleaving linear dispersion codes (ST-CILDC). This thesis shows that ST-CILDC maintains the same upper bound diversity order as the corresponding conventional ST-LDC, and ST-CILDC may double the statistical diversity order over the corresponding ST-LDC with high probability. ST-CILDC systems may show either almost doubled upper bound average diversity order or extra coding advantage in time varying channels.