Multi-hop mobile wireless network design: implicit cross-layer loss models and performance sensitivities

We describe new methods for multi-hop mobile wireless network design, so as to meet performance specifications. We introduce an implicitly defined approximate loss model that couples the physical, MAC and routing layers' effects. The model provides quantitative statistical relations between the loss parameters that are used to characterize multiuser interference and physical path conditions on the one hand and the traffic rates and types between origin-destination pairs on the other. The model considers effects of hidden nodes, node scheduling algorithms, MAC and PHY layer failures and unsuccessful packet transmission attempts at the MAC layer in arbitrary network topologies where multiple paths share nodes. We consider both contention-based as well as scheduling-based MAC protocols. The new methods are based on implicit loss network models developed using fixed point methods. We describe the application of Automatic Differentiation (AD) to these implicit performance models, and develop a methodology for sensitivity analysis and parameter optimization for wireless protocols. We also introduce new methods that utilize on-line feedback from the PHY layer to simplify the joint MAC and routing protocol design. We provide several examples, with realistic scenarios, that demonstrate the benefits of applying these new methods in an integrated manner. We close with current and future work that extends these methods and algorithms towards a Component-Based design, performance analysis and validation of distributed protocols for mobile wireless networks. We argue that this set of ideas provides a very promising approach to 'clean slate' design for such networks and the resulting hybrid broadband Internet.