Coexistence and call admission control in a heterogeneous wireless environment
Nicolas Chevrollier · OpenGrey (Institut de l'Information Scientifique et Technique) · 2006
In today s digital world, various types of users, applications and wireless technologies interact to create a complex and heterogeneous environment. In this thesis, we address two issues introduced by the heterogeneity of the digital world. First, we evaluate the interference generated when multiple wireless technologies operate in close proximity. We develop two coexistence mechanisms to mitigate interference in the 2.4 GHz frequency band: a scheduling scheme for Bluetooth devices known as bluetooth interference aware scheduling and a scheme based on Layer 2 triggered handovers. Second, we investigate how to integrate vertical handovers into call admission control algorithms in order to limit the communication disruption and quality of service discontinuity. We evaluate the impacts of those handovers in terms of packet loss and disruption latency, and develop two call admission control algorithms, namely the probabilistic call admission control and handover-based call admission control algorithms. The former is based on a probabilistic admission decision and the latter includes a bandwidth reservation policy along with preemptive handovers. Both aim at reducing the occurrence of hard handovers in a heterogeneous wireless environment.