Improvement And Simulation Research Of Multipath OLSR Routing Protocol

Mobile ad hoc network is a special format of wireless network,and its has features of mobility,self-organization,multi-hop communication,needless infrastructure,etc.These features determine the flexibility of network structure and organization.It has a good applicable prospect of military,public safety,disaster relief and other aspects.Meanwhile,due to the inherent flaws of wireless transmission,mobile ad hoc network will face more technical challenges.Routing protocol is an integral part of mobile ad hoc network,and It makes wireless communication equipment group as a whole,and coordinates the exchange of data orderly.To a great extent,performance of network is determined by the routing protocol.Therefore,the study of mobile ad hoc network mainly focused on the routing protocols.The main problems researched in mobile ad hoc network are energy saving,service quality,network security and load balance,etc.Many routing technologies are proposed to address these problem,such as multipath strategy,multi-interface strategy,multi-radio strategy,opportunistic routing,etc.The OLSR protocol in mobile ad hoc network is the research object,and multipath strategy is the research direction.Analyzing a large amount of multipath routing protocol research,this paper proposes a multipath OLSR routing protocol based on the mechanism of the next-hop for the deficiency in multipath OLSR protocol research.In addition to using multipath strategy to balanced load and reduce delay,improve the network capacity,the main purpose of the improved scheme is utilizing advantages of proactive routing protocol to improve the multipath protocol for resilience in changing topology and ability to automatically adjust the local overload.So the reliability of data transmission will be further improved.There are mainly two innovations in the optimized scheme.For one thing,the next-hop routing mechanism which is more suitable for proactive routing protocols replaces source routing.Source routing is widely used in the studies of multipath protocol.By strictly specifing the path for packet forwarding,a proactive routing protocol or a reactive routing protocol is able to utilize source routing to simply realize multipath mechanism.However,for the proactive routing protocol of OLSR,source routing restricts its adaptability to the dynamic changes of network.By contrast,the next-hop mechanism is more difficult to implemented in the multipath OLSR protocol.Whereas,it makes the multipath OLSR protocol dynamicly respond to changes of network.For another thing,by double-layer MPR mechanism,the multipath strategy is efficiently implemented in OLSR protocol.It makes finding multipaths less possibile that OLSR senses a part of network topology.Considering the contradiction of the increase of sensing range and reduce protocol's overhead in MPR mechanism,double-layer MPR mechanism separates MPR's functions of formatting TC message and transmitting.While increasing topological informations,it effectively control broadcast,and reduces protocol overhead.Improved multipath OLSR protocol is realized in OPNET Modeler which is a simulation software.The improved algorithm and functionis mentioned in scheme is validated and correctly expressed.Based on the different load condition,a series of simulated experiments contrasting improved multipath OLSR protocol and OLSR protocol is tested in two specific network environment.Experimental data show that the multipath OLSR routing protocol based on the mechanism of the next-hop is able to be realized,and improved multipath OLSR has a advantage over OLSR in media access delay and delivering rate.