In writing this text, we hope to achieve multiple goals. Firstly, we hope to develop a textbook that is useful as a reference for graduate or a supplement to advanced undergraduate classes investigating advanced wireless communications. These topics include adaptive antenna processing, multiple-input multiple-output (MIMO) communications, and wireless networks. Throughout the text, there is a recurring theme of understanding and mitigating both internal and external interference. In addressing these areas of investigation, we explore concepts in information theory, estimation theory, signal processing, and implementation issues as are applicable. We attempt to provide a development covering these topics in a reasonably organized fashion. While not always possible, we attempt to be consistent in notation across the text. In addition, we provide problem sets that allow students to investigate these topics more deeply. Secondly, we attempt to organize the topics addressed so that this text will be useful as a reference. To the extent possible, each chapter will be reasonably self-contained, although some familiarity with the topic area is assumed. To aid the reader, reviews of many of the mathematical tools needed within the text are collected in Chapters 2 and 3. In addition, an overview of the basics of communications theory is provided in Chapters 4 and 5. Finally, in discussing these topics, we attempt to address a wide range of perspectives appropriate for the serious student of the area. Topics range from information theoretic bounds, to signal processing approaches, to practical implementation constraints.