Architecture Design Approaches and Issues in Cross Layer Systems

Wireless communications are a fast grown part of the telecommunication market. While new types of traffic and challenges related to the wireless medium are appearing, the methodologies for designing system architectures are substantially remaining the same. Under the increasing pressure of market, users, and physical medium issues, designers are in the need for new approaches.
Cross Layer becomes than a handy solution for coping with such problems. In fact, it allows both tighter optimizations of the existing functionalities, and the introduction of new ones, that do not fit within the traditional protocol stack design methodology.
However, Cross Layer also carries a risk due to possibly unexpected and undesired effects. In this chapter we want to provide architecture designers with a set of tools and recommendations synthesized from an analysis of the state of art, but enriched with the perspective of the development of future generations of communication systems such as Cognitive Radio.