Diversity-Multiplexing Tradeoff: A Comprehensive View of Multiple Antenna Systems

Diversity-Multiplexing Tradeoff: A Comprehensive View of Multiple AntennaSystemsbyLizhong ZhengDoctor of Philosophy in Engineering Electrical Engineering and Computer SciencesUniversity of California at BerkeleyProfessor David Tse, Chair Motivated by the increasing demand for data rate in wireless systems, a major effort isbeing made to study the use of multiple antennas. It is widely understood that in a fadingenvironment, by using multiple antennas at both the transmitter and the receiver (MIMOchannel), the performance of a wireless link can be greatly improved, both in terms ofimproving the reliability of the link and supporting a higher spectrum efficiency.In this dissertation, we study the performance gain of MIMO systems. We measurethe increase of the capacity by the number of degrees of freedom in the channel, or the spatialmultiplexing gain; and the improvement of the reliability by the diversity gain. We proposea new point of view that unifies these two types of gains: given a MIMO channel, bothgains can be simultaneously obtained, but there is a tradeoff between how much of eachtype of gain any coding scheme can extract. The optimal diversity-multiplexing tradeoffis a fundamental performance limit of a MIMO channel. By studying this fundamentaltradeoff, we can gain important insights on the resource constraint of MIMO systems, aswell as on specific schemes to communicate over such systems.Specifically, we focus on a fully scattered flat fading environment. We adopt ablock fading model, which assumes that the fading channel gains between transmit-receiveantenna pairs remain constant for a block of symbol periods before changing into inde-pendent realizations. We study this channel under both the assumptions that the channelstate information (CSI) is available ( coherent) and is not available (non-coherent) at thereceiver end. While the channel capacity of the coherent case is studied in [24], we com-