Research On Key Technologies Of Interconnecting Mobile Ad Hoc Networks Into Internet

Because of the rapid development of information technology, military warfare isbecoming changing and information superiority has become the commanding heights towin a war in the battlefield. Nowdays, many kinds of Tactical Internet systems, battlefieldreconnaissance and surveillance systems constructed by mobile ad hoc network technologyhave equipped by troops. These systems with more and more growing function have therequirements to interconnect with the military Internet. So, how to guarantee seamlesslyinterconnecting battlefield mobile network and the military Internet is becoming a questionwhich needs to be resolved.In the course of military operations, in order to achieve rapid deployment of thenetwork, the demand on the self-configuration capabilities of military tactical Internet isvery high, including the address autoconfiguration of the devices. Since military FM radioMANET with narrow bandwidth and low rate channel characteristics, the designing of highefficiency and low overhead address auto-configuration protocol for this network is needed.During the lifetime of the military tactical Internet, the network topology may changefrequently. It may be split into several smaller networks; or several smaller networks atsome time will be merged into a larger network. Therefore, the address auto-configurationprotocol needs to be able to handle network partitioning and merging scenarios.In the battlefield, the military tactical Internet and the military IP WAN need tointerchange a lot of command and control information and situational awarenessinformation and intelligence. Military equipments who want to access the IP WAN firstneed to find and select the gateway. In order to improve the reliability and robustness of theinterconnection between the tactical Internet and IP WAN, multiple gateways are usuallydeployed. Facing the demand of interchanging a lot of audios, videos, images, how to findand select a guaranteed QoS gateway among many gateways is essential.In order to adapt to the complex battlefield geographical environment and providereliable and redundant communication needs, the military tactical network usually containsa variety of wireless communication means, the data transmission within the network isdiversity and quick. But the traffics between networks are relayed via gateways, if thegateways do not deployed the load-balancing policy, some gateways may have overloadedload, while others may have less load. To improve the performance of traffics interchangingbetween the tactical Internet and the military IP WAN, the load balancing mechanismbetween multiple gateways should be studied in depth.Aiming at the new requirements of interconnecting MANET and the Internet, thisdissertation focuses on three key issues for realizing this hybrid network, including addressauto-configuration, gateway discovery and selection and traffic balancing. Several solutionshave been proposed to deal with these issues and theory analysis as well as simulationresults have confirmed their effectivities. These research conclusions will promote the fastdeployment of MANET and increase the importance of MANET in the more fields.This dissertation makes the following specific contributions: (1) Aiming at the narrow bandwidth and low rate channel characteristics of themilitary FM radio MANET, an IP address auto-configuration protocol for MANET withmultiple gateways was presented in this dissertation. This protocol can provide the mobilenode with a unique local address and a unique glolal address. This protocol can guaranteethe configured address uniqueness within the MANET by using duplicate address detectionprocedure. This protocol can also cope with the network partition and merging question.(2) Aiming at the new demand of interchanging data between tactical Internet and themilitary IP WAN, A load-based adaptive gateway discovery protocol was proposed in thisdissertation. The load-based adaptive gateway discovery protocol can dynamicly tune theTTL of the gateway advertisements flooded by the gateway based on network traffic loadstatus.Aiming at the topology characteristics of the military tactical Internet, an analysismodel focusing on the proposed load-based adaptive gateway discovery protocol and theexisting gateway discovery protocols is presented in this dissertation. The analysis resultsshow that the proposed adaptive gateway discovery protocol can adapt to the networkconditions dynamicly and control the overhead in a reasonable range. Simulation resultsshow that the proposed protocol can improve packet delivery ratio and end to end delayeffectively.(3) A QoS-based gateway selection algorithm was proposed in this dissertation. TheQoS-based gateway selection algorithm selects an optimal gateway based on three QoSmetrics: traffic load of gateway, path quality from MANET node to the gateway and hopcount to the gateway for integrating MANET and the Internet. The Simple AdditiveWeighting method is used to combine these three QoS metrics to outrank the optimumgateway. Gateway with the smallest weight will be selected as the optimal gateway.Simulation results show that the proposed algorithm can achieve a better packet deliveryratio and end to end delay.(4) Two traffic load balancing routing algorithms among multigateways werepresented in this dissertation. MANET and Internet have many differences. Thesedifferences are not only the structure and topology of the networks, but also communicationpatterns of nodes in both networks. Therefore, it is a challenging problem for MANET toaccess to the Internet due to these differences, where load-balancing is an importantproblem. In this dissertation, two traffic balancing routing algorithms among multigatewayswere presented to resolve the traffic balancing problem in the MANET and distribute trafficload among gateways evenly. Through simulation experimental results, the proposedrouting algorithms can have a good performance to distribute traffic evenly and consume areasonable cost.