Research On Key Techniques Of Mobility Management In Next Generation Networks

Mobile communication technologies have become one of the most challenging and promising issues in modern communications. With the fast development of wireless communication technologies and the wide deployment of all-IP technique, the next-generation wireless mobile network must be integrated with various radio access technologies to support seamless roaming of mobile hosts. In order to guarantee mobile hosts roaming among different subnets freely meanwhile maintaining on-going sessions, it is vital to use effective mobility management methods. How to conceive rational and optimized vertical handoff algorithms and mobility management schemes has become significant in Radio Resource Management (RRM) for the next-generation mobile communication system.All-IP wireless heterogeneous integrating system is composed of cellular mobile networks, wireless local area network, satellite communications and broadcast communications. In view of various types of access networks and traffics such as voice, data, and multimedia, this dissertation focuses on mobility management in all-IP wireless heterogeneous networks, covers vertical handoff algorithms and mobility management schemes. Several novel algorithms and schemes have been proposed and verified to be effective by both analyses and simulations, which can be described as follows.Firstly, this dissertation proposes an efficient handoff algorithm for wireless heterogeneous networks constructed by the loosing couple architecture between wireless local area network (WLAN) and universal mobile telecommunications system (UMTS). This vertical handoff algorithm takes the received signal strength and its accumulation as handoff trigger criterion to adapt with the network conditions and deduce theoretic analysis of mean handoff number and dropping probability. The results of simulations indicate that the proposed algorithm has better performance than the conventional algorithm based on the absolute received signal strength (RSS).Secondly, this dissertation studies vertical handoffs combined with RRM technologies to improve system performance. The proposed vertical handoff algorithm introduces access control, bandwidth borrowing and compensation, and load balance control to allocate radio resource based on different traffic types. The results of simulations indicate that the proposed algorithm is able to reduce the dropping probability under the same block probability, and guarantee the best quality of service for voice in the three traffic types.To minimum unnecessary handoff number, this dissertation proposes an improved vertical handoff algorithm considers some network parameters including velocity, current RSS, predicted RSS and available bandwidth unity of candidate networks. The forward differential prediction algorithm is used to get the predictive RSS, which can trigger a handoff in advance. And the pre-decision method is applied before the handoff decision module, which can filter the unnecessary data and provide accurate handoff trigger. Fuzzy logic principle based evaluation and decision algorithm is applied to the overlay network of UMTS and WLAN, which can save the mobile host memory to store the rule bases and saves the time to defuzzy within the rule bases. Furthermore, the intelligent vertical handoff algorithm with the aid of grey theory and dynamic weights adaptation is proposed. The Grey Prediction Algorithm (GPA) predicts the predictive received signal strength accurately. The decision rule based on fuzzy logic theory takes received signal strength, available bandwidth, and monetary cost of candidate networks as input metrics. And the weight of each metrics is adjusted along with the networks changing to trace the network condition. Simulation results demonstrate that the proposed algorithm provides high performance in heterogeneous as well as homogeneous network environment.Fourthly, this dissertation presents an improved IDMP-based macro-mobility management (IDMP-MM) mechanism for heterogeneous wireless networks. The proposed mechanism adopts Layer-2 fast handoff trigger, the edge-cells controller for improving intra-domain mobility, and the pre-registration method with the aid of address-table mapping between mobility agents to enhance inter-domain mobility. It describes the procedures of intradomain and interdomain handoff in IDMP-MM solution, and gives the performance analyses of IDMP-MM. The simulation results show that the IDMP-MM mechanism can provide efficient mobility management to reduce the binding update signaling cost, the number of buffering in-flight packets, and execute fast handoff for ongoing calls.In the end, this dissertation focuses on mobility management schemes for the protocols of identifier and locator separation. The generic mobility management scheme for protocols of terminal-based identifier and locator separation is proposed. By combining with Fast Mobile IPv6, the proposed scheme provides fast and simultaneous-moving handoff management without packets loss. And it gives the fast handoff procedure of the proposed scheme and several modified signal formats. This scheme is applicable to support Shim6 mobility, which is demonstrated the benefits on handoff latency and handoff signaling cost.Finally, the conclusion is presented as well as future research trends.