A Proactive and Distributed QoS Negotiation Approach for Heterogeneous Environments: An Evaluation of QoS Signalling Overhead

The recent boom in radio access technologies and their diversification have opened the way to new studies on quality of services (QoS) management in such heterogeneous environments. Indeed, the need for efficient QoS mechanisms is increasing since these new technologies provide scarce resources (e.g. unpredictable bandwidth and variable error rates). In this environment, nomadic hosts have a greater choice of access technologies. Thus, keeping the same QoS level for one user's application, anywhere user is connecting, may require some mechanisms to control QoS in each target network. In this framework, we propose to adopt a proactive and dynamic negotiation approach coupled with the hand over decision algorithm implemented in (L. Suciu et al., 2007). In this approach, decision parameters (e.g. throughput, transmission delay, etc.) can be distributed between several hierarchical entities in the network. If one decision parameter's value should be negotiated, negotiation process will be immediately started before taking the hand over decision. A comparison of several QoS parameter distributions (e.g. QoS parameters are stored either in mobile terminal or in control entity located more or less deeply in the core network) has been carried out thanks to a mathematical model, which takes into account the size of all messages necessary to achieve QoS parameter negotiation during a mobility scenario.