| The Ad hoc which is based on the VANET(Vehicular Ad hoc Networks)are the most common forms of the interconnectedness of all things,and has become the basic network on which the everyone work and live.Restricted by the architecture ossification and mobility of network,the innovation of Ad hoc lacks endogenous impetus,which makes people's expectation of Ad hoc service impossible to be satisfied.Therefore,opening the core function of the network and improving the Ad hoc service ability are the most urgent needs for the sustainable development of the Ad hoc.In recent years,flexible and programmable software defined networking provides a realistic basis for the realization of service oriented network function combination.Integrating the idea of software definition,the Software defined Ad hoc has strong controllability.Therefore,the network function combination oriented to Software defined Ad hoc is considered as the fundamental method to improve the Ad hoc service capability.At present,the following problems exist in the research of function composition mechanism of Software defined Ad hoc:(1)The related research and achievements focus on the improvement of network local performance,and seldom touch on the essential innovation of network function structure design.(2)The traditional ad hoc function structure is relatively closed,and lacks the ability to realize dynamic network function combination.(3)Frequent topology changes increase the possibility of service interruption,the link recovery mechanism is difficult to guarantee the network service to be continuously effective.Aiming at the above three problems in the realization of network function combination in the Software defined Ad hoc,it takes the design innovation of the function structure of the Software defined Ad hoc as the starting point,by means of flexible control,abstract decomposition and dynamic combination of network functional structure,it concreteness Ad hoc service ability to the network basic transmission ability,the service providing ability and the service guarantee ability,solutions propesed one by one.Firstly,the flexible control mechanism of Ad hoc function structure defined by software is analyzed,and the extensible network control plane and flexible data plane are established to support the efficient transmission of control flow and data flow.Secondly,it decomposes and abstracts the basic unit of the network function combination-Base Protocol,building an instantiated network function combination inside a network node and on a network wide scale Dynamic Protocol Stack,in order to improve the performance of nodes and optimize the network routing to ensure the dynamic provision of network services.Thirdly,a fast and effective recovery method of network service under link failure is proposed to ensure continuous network service.Specifically,the main research results as follows:1.In view of the lack of innovation in the functional structure design of Software defined Ad hoc,we presents research ideas and design principles for the essential problems of Software defined Ad hoc,such as control elements,functional structure and control mode.Firstly,the reasonable convergence software defines the control elements of the Ad hoc,and supports the SDN to be extended to mobility.Secondly,the hybrid control structure of the Software defined Ad hoc is established,which is "physically distributed and logically centralized",it analyzes the workflow of network control plane and data plane,and supports the simple networking.Thirdly,under the hybrid control structure,a controller election algorithm is designed according to the requirement of mobile network.Finally,the performance of control plane and data plane is analyzed and compared.The convergence time and resource cost of the algorithms are analyzed.It is verified that the Software defined Ad hoc has good basic transmission ability.2.To solve the problem that the Ad hoc lacks the basic unit of network function combination,it decomposes and abstracts the basic unit of Software defined Ad hoc,and dynamic protocol stack is constructed to improve the service providing ability of network nodes.Firstly,according to the hybrid network control structure,the basic unit of the Software defined Ad hoc function is abstracted as base protocol to open the core function of the network.Secondly,a method of constructing network nodes based on base protocol is proposed,which is compatible with traditional network nodes.Thirdly,according to the service requirement,considering both resource and utility,it designs the dynamic protocol stack construction algorithm in the node.Finally,simulate the related algorithms and analyze the node performance.The results show that the above algorithms can achieve higher service acceptance rate and average utility of instances,and the Software defined Ad hoc nodes with network function composition mechanism can have good natural ability of service provision.3.In order to solve the problem of the lack of the realization method of network function combination in the whole network,it presents a service-oriented and global algorithm for constructing dynamic protocol stack among nodes,and routing as the physical deployment form of dynamic protocol stack between nodes,which improves the ability of global service provision in software defined Ad hoc.Firstly,a hierarchical routing model based on service characteristics is proposed as the basis of building dynamic protocol stack.Secondly,a service node selection algorithm is designed to build dynamic protocol stack among nodes.Thirdly,based on ordered service nodes,deploy Software defined Ad hoc routing.Finally,a simulation experiment platform is built to compare and analyze the related algorithms.The results show that the Software defined Ad hoc routing results in more balanced energy consumption,lower resource occupancy and better network utility,which validates that the network function combination mechanism improves the global network ability of service provision.4.To solve the problem of wireless environment affecting the stability of network function combination,a dynamic protocol stack reconstruction method based on service path recovery is proposed.Firstly,the concept of service path is proposed,which takes into account the link state and the order of service,thus transforming the relatively complex and abstract dynamic protocol stack reconstruction problem into a service path recovery problem which is easy to be implemented by engineering.Secondly,is proposes a core algorithm for dynamic protocol stack reconstruction-service path staged recovery algorithm,which combines backup recovery with computational recovery to improve the timeliness of dynamic protocol stack reconstruction,to ensure the validity of dynamic protocol stack reconstruction.Finally,the simulation analysis correlation algorithm.The results show that the hierarchical service path recovery algorithm has more advantages in the aspects of recovery delay and recovery success rate,which validates that the network function combination mechanism improves the service guarantee ability of Software defined Ad hoc. |
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