The Research On Key Technologies Of Wireless Mesh Network Virtualization

Wirelessmeshnetwork(WMN)haslotsofobviousadvantagesincludinglowcost,convenien-t deployment, wide coverage, high throughput, etc. These advantages make WMN quite suitablefor last-mile Internet access. Governments and operators in many countries have paid attention toWMNs, and deployed increasingly more WMNs in practice. However, several challenging prob-lems emerge in actual deployments, such as a user cannot get guaranteed bandwidth, packet lossrate is relatively high, and a mobile user tends to suffer from link disruption. Wireless mesh net-work virtualization is adopted to overcome these problems. Though establishing virtual networks,wireless mesh network virtualization technologies shield details of substrate networks to users,and serve users on their demands. Therefore, the wireless mesh network virtualization has greatsignificance for the evolution of WMNs.A theoretical framework for wireless mesh network virtualization is established in this the-sis. The framework contains three aspects, i.e., separation, aggregation and hybrid wireless meshnetwork virtualization. Based on typical application scenarios, key techniques of wireless meshnetwork virtualization are studied from these three aspects. For separation wireless mesh net-work virtualization, resource allocation mechanisms are designed for both unicast and multicastservices to guarantee the isolation among virtual networks. For aggregation wireless mesh net-work virtualization, cooperation protocols are designed to abstract multiple physical devices intoa unified logical device. The hybrid wireless mesh network virtualization is the combination ofthe above-mentioned two aspects, in which both separation of virtual networks and aggregation ofheterogeneous physical networks should be considered. The main contents and contributions ofthis thesis are described as follows.First, the concept of virtual access network is firstly proposed, and the corresponding WM-N architecture and the virtual access network embedding algorithm are designed. Virtual accessnetworks are built to guarantee the end-to-end bandwidth requirements of users when a WMNis deployed as an access network for the Internet. In order to achieve this goal, OFDMA-baseddual-radio mesh node, partially overlapped channel-based channel assignment algorithm, and theWMN architecture are designed to insure the separation among the virtual access networks. Agreedy and genetic-based algorithm for virtual access network embedding is also represented inthis thesis. When multiple Internet gateways exist in the WMN and the total bandwidth require-ment of users exceeds the total capacity of these Internet gateways, the algorithm can enhance the utilization of the substrate network resources.Second, an algorithm for multicast service-oriented virtual network embedding in the WMNis proposed for the first time. Based on opportunistic rebroadcasting, the algorithm can satisfy thereliability requirements of virtual links under the condition that physical wireless links are lossy.According to appropriate scheduling, the algorithm also minimizes the activation time of eachvirtual network, which improves the utilization of substrate network resources.Third, a network-leading association scheme is firstly proposed. Movement of a station maytrigger its handoff between access points, which can incur interruption of network connection.Aiming at this problem, the network-leading association scheme is designed to achieve seamlessroaming of the moving station in the coverage of the WMN. With this scheme, the whole WMN isvirtualized as a single access point with which the station is associated, and no explicit handoff isneeded. Theschemecanadaptivelyselecttheoptimalmeshaccesspointwithinthecommunicationrange of the station to forward its packets, which improves the throughput and reduces end-to-endairtime and packet loss rate.Finally, WMN and powerline-based communication framework for smart grid communica-tions as well as algorithms for virtual network embedding is proposed for the first time. Accordingto communication requirements of smart grid, a hybrid framework combining both WMN andpowerline communication network is designed. Based on the framework, virtual networks areestablished for various types of services respectively, and are embedded onto the heterogeneoussubstrate networks. Reliability of realtime services is satisfied through transmission diversity en-hancement, while throughput of best-effort service is maximized.The theoretical framework and the key technologies of wireless mesh network virtualizationare conducive to solve challenging problems of WMNs. Thus, wireless mesh network virtualiza-tion is a powerful impetus WMNs.