Cross-layer design in wireless networks

In this thesis, cross-layer optimization techniques for wireless networks are investigated. An introduction to the concept of cross-layer design is provided, reviewing the related literature, from both an architectural and an analytical point of view. Three original contributions, which jointly address the optimization at different levels of the protocol stack are then presented. The first contribution refers to a theoretical approach to channel allocation in multichannel ad hoc networks, where each node is provided with multiple radio interfaces. An algorithm for the joint solution of congestion control, channel allocation and transmission scheduling is proposed. The second contribution refers to a cross-layer optimization framework in the context of standard IEEE 802.11WLAN. A mathematical model for the link performance is developed, and a sufficient description for the medium status is defined which allows to account for propagation and interference conditions. The optimization framework is used to develop algorithms for rate adaptation and VoIP quality enhancement which are adaptive to a broad range of working conditions. Resource allocation in wireless cellular networks is also addressed and the problem of trading fairness for physical layer efficiency is investigated by means of a simple algorithm spanning PHY, MAC and LL layers. In the end, additional published contributions related to the cross-layer paradigm are introduced, regarding microeconomic aspects in resource allocation and efficiency considerations about scatternet topologies in Bluetooth networks.