Research On The Networking Technology In Software Defined Mobile Ad Hoc Network

Mobile Ad Hoc Network(MANET)is composed of a group of mobile nodes that do not require infrastructure such as base stations.It conducts dynamic networking in a selforganizing manner.Each node makes routing decisions independently and needs to adapt to constant changes of the topological structure.MANET is widely used in military warfare,emergency rescue,disaster relief and other fields.With the continuous development of wireless communication technology,the requirements for network quality are getting higher and higher.Due to the distributed characteristics of MANET,it is subject to the local visibility of network resources during networking,and it is difficult to provide the best routing and optimal resource utilization based on the status of the entire network.The centralized control idea of Software Defined Network(SDN)provides new ideas for solving the above problems.At present,researchers have proposed the introduction of SDN technology into MANET,and proposed the concept of Software Defined Mobile Ad Hoc Network(SDMANET).However,this technology is not yet mature and there are many problems to be solved urgently.For example,in case of constant movement of nodes communication stability cannnot be guaranteed,resource utilization is low,and routing information maintenance overhead is high.Based on the networking technology in SDMANET,this dissertation provides solutions to the above problems.The main research work and innovations are as follows:First,this dissertation proposes a networking method based on multi-mode radio and backbone network optimization.The SDN controller communicates with network nodes through an out-of-band control channel,and then controls the entire network.In order to improve the channel utilization,this dissertation adopts the centralized dominance set method to select the dominant node as the backbone node,and only the backbone node establishes a control connection with the controller.At the same time,an improved algorithm is proposed for the packet loss rate caused by periodic reselection of backbone nodes,and the identities of backbone nodes and ordinary nodes are switched in a gradual manner.In order to avoid the backbone nodes from carrying too many control messages,this dissertation designs a load balancing strategy in which ordinary nodes select backbone nodes.Experiments show that this method can effectively reduce the network packet loss rate.Secondly,this dissertation proposes a centralized routing method.The SDN controller performs routing calculations after collecting global topology information and resource status information,and combines the A* algorithm to optimize the routing path in terms of link stability and delay.In addition,this dissertation uses source routing to issue flow tables to reduce routing control overhead,and designs response mechanisms for link interruptions to improve the robustness of the network.Finally,this dissertation uses Riverbed simulation software and RYU controller to build an SDMANET simulation platform to verify the effectiveness of the centralized backbone network construction algorithm and routing method proposed in this dissertation.The simulation results show that this method can effectively reduce the routing control overhead and significantly improve the network performance such as delay and packet loss rate.