Book excerpt: Cross-layer design seeks to enhance the capacity of wireless networks significantly through the joint optimization of multiple layers in the network, primarily the physical (PHY) and medium access control (MAC) layers. Although there are advantages of such design in wireline networks as well, this approach is particularly advantageous for wireless networks due to the properties (such as mobility and interference) that strongly affect performance and design of higher layer protocols. This unique monograph is concerned with the issue of cross-layer design in wireless networks, and more particularly with the impact of node-level multiuser detection on such design. It provides an introduction to this vibrant and active research area insufficiently covered in existing literature, presenting some of the principal methods developed and results obtained to date. Accompanied by numerous illustrations, the text is an excellent reference for engineers, researchers and students working in communication networks.