Key Technology Research Of Clustered MANETs Based On Trust Mechanisms

Mobile ad hoc networks(MANETs)are self-organized wireless systems which are formed by mobile nodes with distributed protocols. MANETs can be used in the occasions where basic infrastructures and equipments are not easy to deploy. They can also be applied in temporary applications. MANETs are convenient for deployment, thus they have broad commercial future and important military value. They are the primary ingredients of next generation networks.However, the characteristics of MANETs as distributed systems with acentric structure, open wireless channels and scarce energy bring out many problems on security, reliability and performance improvement. Hence, the key techniques of MANETs, such as clustering and routing become urgent affairs to enhance the security, stability and capability of the systems. Cryptography method is a traditional security way in MANETs, but it has obvious defects in key distribution, key management, costs of communication and computing. On the contrary, trust mechanism can avoid the above problems because of its peculiarity of less complexity, self-organized structure, incentive effect and many other advantages. Trust mechanism can be combined into the key techniques of MANETs, and the security, reliability, adaptability and working efficiency in MANETs will be greatly improved.Trust is the major basis of my thesis and we have made thorough and systemic research on the key techniques of MANETs combining trust principles. Trust evolvement rule, MANET clustering, routing, trust authentication, and the holistic design of secure and trustful MANETs are the main aspects of our work. In summary, the main contributions of our work are as follows:(1) An improved trust triangle tunnel downfallen model called TTTD is proposed, which can intuitively denote the evolvement trend of trust ingredients. Since MANET nodes are always moving and the environments change rapidly, the impact of time must be considered adequately. After making sufficient suppose, analyse and proving about trust decay and evolvement rules, a triangle tunnel downfallen model is proposed. Each composing partition of the model is particularly described and it is a intuitive and effective representation means for time-related trust in mobile ad hoc networks.(2) A MANET clustering algorithm based on maximum objective trust-MOTBCS is proposed. To address the lack of original trust information and the strong dynamic nature of MANETs, we emphasize the objective factor of trust attributes, and design a mathematical model for the evaluation of objective trust, which is according to the count of stability links to evaluate the reliability of interactive nodes. Theoretic analysis and experiments illuminate that MOTBCS can achieve better performance in building reliable, efficient, and stable systems of large-scale clustering MANETs. (3)A hybrid clustering protocol-HMCPRE is proposed, based on reputation valuation and resident energy. HMCPRE can construct a stable, credible and efficient clustering MANET sytem mainly considering reputation degree and energy remaining of nodes. We have also carried out further research on the independent analyse of cluster heads in probability ways. Simulation results show that HMCPRE can not only form a fine layout which has good cluster head distribution, but also effectively restrain the attack of malicious nodes and the damage to the stability of MANETs.(4) This thesis puts forward a secure routing protocol-CTSSRC, which is based on cross layer trust scheme. CTSSRC adopts the thought of cross layer, synthesizing the trust information of each layer in ad hoc networks, and taking the cryptography mechanism as an assistance. The trust method adopted by CTSSRC can be closely combined with cryptography designs, including ECDSA and traditional cryptography ways. They can support each other and the dependence and coupling degree between them are rather low, as well as the system is robust. CTSSRC makes full use of the advantage of cross layer structure, and instructs routing based on the trust information of multi-layers. It can avoid the limitation of secure routing ways which merely depend on the invasion inspection of routing attacks. Two-hop neighbors adopt limited recommending mechanism to estimate trust and this way greatly reduces the communication and computing costs of trust evaluation. Multi-path source routing mechanism can evaluate the path quality based on trust information, and the source node send packets in multiple pathes, which can avoid load congestion. Trust mechanism also has extraordinary incentive effect, so it can strengthen the cooperation between nodes and raise the adaptable ability and enhance the whole performance of the system. Analysis results and simulation experiments both show the better performance of CTSSRC on the circumstances where malicious attack behaviors exist.(5) This thesis proposes a kind of MANET distributed trust proving language-RT~M based on role trust, and then, distributed authentication framework RT-M and authentication algorithm tc-ask are designed. Due to the characteristics of distributed deployment, open channel and acentric structure of MANETs, there are a lot of weakness such as bad cooperation and low authentication efficiency in the previous secure access control methods and mutual trust mechanisms. Automatic trust negotiation-ATN can set up trust relationship between resource requesting partners and providing partners by the means of mutual exposure of credentials and access control strategies. The interactive partners needn't know others'access control strategies and negotiation process generally needn't artificial participation. RT~M is a kind of distributed trust proving language which can process trust negotiation automaticly and efficiently in MANETs. RT-M defines different application roles to make distributed trust proving, avoid unrelated credential fetching, thus it can improve efficiency notably. Experiment results and tc-ask algorithm indicate that RT-M consumes less interactive time and communication cost than normal methods and it is a preferable distributed trust authentication mechanism which is suitable for the environments of MANETs.This thesis is organized with the thought of trust and presents several solutions on the key techniques of MANETs. Our design combines trust mechanism into MANETs. As a result it helps to construct secure, trustful, effective and stable MANET systems and contributes much to the further study and deployment of MANETs.