Mobility management and admission control in heterogeneous wireless networks

The forthcoming fourth generation (4G) heterogeneous wireless networks are a mixture of overlapped networks using different wireless access technologies and addressing different needs from the users. Due to mobility, the users are able to switch connections among networks and hence to perform the so-called horizontal and vertical handoffs. The present thesis makes contributions to the field of mobility management with focus on handoff management and connection admission control in heterogeneous wireless networks. Two different integrated heterogeneous systems are investigated: 1) the interworking of cellular networks with wireless local area networks (WLANs) based on the I E E E 802.11 standard; 2) the interworking of cellular networks with wireless metropohtan area networks based on the I E E E 802.16e standard. To this end, first we develop a novel vertical handoff decision algorithm by modeling the vertical handoff problem as a Markov decision process. Our model considers the important tradeoff among the quality of service (QoS) of the connection and the signaling cost of performing a vertical handoff. We also take the connection duration into consideration for the handoff decision. Second, we propose an analytical model for admission control in c e l l u l a r / W L A N interworking and investigate the combination of different admission control policies. Our model considers mobihty of users, capacity and coverage of each network, admission policies, and QoS in terms of blocking and dropping probabilities. We introduce the concept of policy functions to model the admission control policies and formulate two different revenue maximization problems. T h i r d , we extend the virtual partitioning technique w i t h preemption for admission control in cellular/802.16e interworking. We propose admission control algorithms for each type of connection request. We also describe the expected mobility scenario in such integrated system. Finally, to achieve joint design at the connection-level and packet-level, a joint QoS optimization approach is used.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat