Advanced Signal Processing Techniques for MIMO

Rapid growth in mobile computing and other wireless multimedia services is inspiring many research and development activities concerning high-speed wireless communication systems. The main challenges in this area include the development of efficient coding and modulation techniques to improve the quality and spectral efficiency of wireless systems. Multiple-input multiple-output (MIMO) techniques for wireless communication have recently emerged and offer a powerful paradigm for meeting these challenges. In particular, MIMO systems constitute a unified way of modeling a wide range of different communication channels, which can be handled with a compact vector-matrix notation. This thesis proposes new signal processing techniques for two representative cases of MIMO systems: (a) systems employing multiple transmit and receive antennas, and (b) systems with multiple users transmitting simultaneously and overlapping in both time and frequency. Owing to the common MIMO system model notation, similar signal processing techniques are applicable to both scenarios as will be demonstrated in the thesis. Chapter 2 gives an overview of the recent development in space-time coding and signal processing techniques for MIMO communication systems having multiple antennas. We first review the information theoretic results on the capacities of wireless systems employing multiple transmit and receive antennas. We then describe two representative categories of space-time systems, namely, the BLAST systems and systems employing space-time block coding. The extension of MIMO techniques to frequency-selective channels is also addressed. Finally, alternative coding and signal processing techniques for wireless systems employing multiple transmit and receive antennas are also briefly touched upon. The most costly element of a multiple antenna device is usually the RF chains (amplifiers, filters, digital-to-analog converters, etc.). A promising approach for reducing the cost and complexity while retaining a reasonably large fraction of the high potential data rate of a MIMO system is to employ a reduced number of