Over the last twenty years, dramatic advances in wireless technology have redefined the basic terms of modern living. In bringing about the wireless revolution, both the theory and practice of communication and networking have had to adapt and evolve in fundamental ways. Perhaps one of the most significant changes is the much closer coupling between the design of physical-layer functionalities such as coding and modulation, and the design of higher-layer functionalities such as contention resolution, scheduling, routing, and congestion control. This closer coupling is characteristic of the cross-layer paradigm, which has strongly influenced the design and implementation of wireless systems since the beginning of the century. Fundamental Performance Limits in Cross-layer Wireless Optimization reviews some key problem settings and results where the cross-layer design paradigm has significantly influenced our understanding of communication systems in recent years. Furthermore, in order to explore the fundamental performance limits of wireless systems operating under the cross-layer paradigm, it shows how information theory and network theory can be leveraged to study issues such as channel modeling, coding, source burstiness, throughput, delay, multi-user interference, multi-path fading, and energy constraints in a more coherent overall analytical and design framework.