On Optimization of Multiuser Multiple Input Multiple Output Communication Systems

Abstract

<p>This thesis considers the Shannon capacity of multiuser multiple input multiple output (MIMO) wireless communication systems. That is, the fundamental limit on the rates at which data can be reliably communicated. The focus is on scenarios in which the channel has long coherence times and perfect channel state information is available to both transmitters and receivers. The thesis considers two important design problems in multiuser MIMO wireless communication systems: the design of the sumrate optimal input distribution for the MIMO multiple access channel (MIMO MAC), and the design of the sum-rate optimal input distribution for the MIMO broadcast channel (MIMO BC).</p> <p>The thesis considers algorithms for solving these design problems that are based on the principle of iterative water-filling. The contributions of the thesis are twofold. First, a correct and rigorous proof of convergence of the family of water-filling algorithms is derived. This proof overcomes weaknesses in the previous attempts of others to prove convergence. Second, an efficient algorithm is presented for the water-filling procedure that lies at the heart of the iterative water-filling algorithm. This algorithm will open the door for further efficient utilization of the iterative water-filling algorithm. This novel algorithm is based on the principle of Fibonacci search, and since the iterative water filling algorithm involves repeated water-filling procedures, the impact of this efficient algorithm is magnified.</p> <p>The outcomes of this research are that the iterative water-filling algorithms are mathematically validated for the above-mentioned design problems in multiuser MIMO wireless communication systems, and that the implementation of these algorithms is made more efficient through the application of the efficient Fibonacci search method for the underlying water-filling procedure.</p>