A Hierarchical General Purpose Optimisation Framework for Wireless Networks

A current trend in wireless networks is to support the integration of multiple services on a composite (multimode) access network infrastructure combining different cellular network and Wireless Local Area Networks (LAN) technologies. The performance of services provided to mobile multimode devices is affected by variations in the wireless network and equipment resources as well as the selection of the different possible protocol stack combinations. These choices, made possible by flexible multi-mode terminals and network equipment, can enable optimisation for performance, resource utilisation or other characteristics (such as security). Dynamic cross-layer optimisation in the protocol stack will provide the best use of resources to most appropriately support different services to mobile multi-mode equipment. In this paper, we compare a centralized optimisation approach with a distributed optimisation approach. Based on this, a hierarchical, constraint based optimization framework is presented. We illustrate in the paper that this general optimization framework can combine the advantages of both approaches. At the same time, it can be extended to allow for hierarchical optimisation across different network levels as well as different protocol layers.