Research On Optimization Schemes For Network-based Mobile Multicast

With the rapid development of wireless and mobile communication technologies, smart mobile devices increase greatly and mobile data expands sharply, which spawns a booming for mobile Internet. Due to the inherent efficient group communication, mobile multicast can greatly save network resources and improve the efficiency of data transmission, which can meet the requirements of growing number of mobile users. Therefore, mobile multicast has attracted widespread concerns and has become a hot research topic. The development of mobile multicast depends on the mobility management protocols and improves with its development. Current centralized-based and host-based mobile multicast schemes have non-optimal routing, higher delays and signaling costs, and single point of failure issues. Besides, network-based mobile multicast schemes lack of multicast source mobility and distributed solutions. For this, IETF has conducted related research for many years, but no standards have been issued until now. Therefore, this dissertation mainly studies the optimization schemes for network-based mobile multicast based on the analysis, simulation and experimentation.The main research work and contributions of this dissertation are summarized as follows:1. To support the multicast source mobility in Proxy Mobile IPv6(PMIPv6) networks, this dissertation proposes two PMIPv6extension-based mobile multicast source support schemes by extending the signaling messages as well as mobility options, and adding the corresponding multicast forwarding states. This scheme makes the multicast stream transmit in PMIPv6networks through bi-directional tunnel or direct routing, and guarantees the continuity of the communication under the movements of the multicast source. The analytical results show that this scheme has a smaller protocol cost. The experimental results verify the feasibility and evaluate the performance of multicast handover delay, which shows that PMIP-BT is suitable for the higher multicast source handover frequency and less optimized routing from the Mobile Access Gateway (MAG) to the multicast domain circumstances, while PMIP-DR is suitable for the lower multicast source handover frequency and more optimized routing scenarios.2. Extending PMIPv6to support the multicast source mobility needs to modify existing mobility protocols, which increases the complexity and then increases the difficulty of deployment. For this, this dissertation proposes two light-weight multicast source mobility support schemes based on Multicast Listener Discovery (MLD) Proxy. These schemes only need to deploy MLD Proxy function on MAGs and do not need any modifications on PMIPv6, which facilitates the deployments and applications. The analytical results show that both of the schemes have a better performance in terms of protocol cost than the host-based schemes. The performance of multicast handover delay and packet loss on handover is evaluated by experiments and simulations, which indicates that the two schemes are suitable for different application scenarios.3. Current mobile multicast schemes are mostly based on centralized mobility management protocols such as PMIPv6. The centralized deployment and management of Local Mobility Anchor (LMA) induces many problems, such as non-optimal routing, higher handover delays, larger signaling costs, no support for inter-domain handover and so on. To solve these problems, this dissertation proposes a mobile multicast scheme based on the distributed PMIPv6. A prefix-aggregation based partially distributed mobility management protocol is proposed firstly. This protocol distributes the LMAs and manages the prefixes of the LMAs, which enables the inter-domain handover. The optimized routing can always be achieved by using IP anycast routing, which optimizes the data transmission path and reduces data delivery cost and delay. Based on this, an efficient mobile multicast scheme is proposed to support the mobility of both multicast sources and receivers, which solves not only the inefficient routing issue, but also the tunnel convergence problem. The analysis results show that this mobile multicast scheme can improve the performance in terms of location update cost, packet transmission cost, multicast join cost and scalability of the number of LMA's routing entries.4. The existence of centralized mobility anchors in centralized and partially distributed mobile multicast schemes is likely to cause single point of failure issue. With the increase of mobile devices and mobile data, this problem will be more serious. Therefore, this dissertation introduces a multiple upstream interfaces MLD Proxy based fully distributed mobile multicast scheme. A Chord based fully distributed mobility management protocol is firstly proposed, in which no centralized entities exist. The robustness of this protocol is ensured by introducing Chord ring to manage the distributed mobility anchors and their prefixes. Besides, considering the MLD Proxy is not well supported in some specific scenarios, a multiple upstream interfaces MLD Proxy based fully distributed mobile multicast scheme is proposed, which can support both multicast source mobility and multicast receiver mobility efficiently. Both of the inefficient routing issue and tunnel convergence problem are solved in this scheme, which improves the performance of mobile multicast service. The analysis and simulation results show that this scheme has a better performance in terms of packet transmission cost, tunnel convergence, route optimization and so on.The proposed network-based mobile multicast optimization schemes in this dissertation have a high theoretical and practical value, which lays a solid foundation for the deployment of mobile multicast. The light-weight multicast source mobility support scheme based on the MLD Proxy has been accepted as a working group draft by IETF, which will soon be published as a RFC.