The Research On Key Technologies Of Heterogeneous Wireless Networks

The future large-scale wireless communication networks are widely used and their complexity and heterogeneity makes their Quality of Service very crucial. Undoubtedly, the personalized and various communication ways for different customers will impact the characteristics, structures, protocols and designing approaches of future wireless communication networks. Nevertheless, heterogeneous wireless network can harness the features of different wireless networks to make a joint effort to its performance for providing better and quicker access services to end users. To realize the above aim, coordinated and seamless communications between different network systems and users platforms are very critical to build a self-organized, scalable and reconstructible network.In comparisons with homogeneous network, most traditional networking technologies cannot be utilized in heterogeneous network environment. Therefore, this dissertation proposed some algorithms and schema for improving current secure routing, QoS mechanism and distributed authentications in heterogeneous wireless communications environments as follows:(1) Node Reputation Routing (NRR) approach is proposed by combining virtual sub-network and physical sub-network to deal with the routing security in wireless network. Direct estimation and indirect estimation are adopted to evaluate the reputation level of nodes in a specified physical network topology. Some nodes falling in a same reputation range make one virtual sub-network indicating corresponding security and QoS. Additionally, right routes will be determined according to the quality of its link by nodes in one virtual sub-network. The experimental results show that the proposed model can recognize the malicious node and choose the optimum route to avoid the selfish nodes effectively.(2) A novel QoS mapping model is proposed in this dissertation to improve the QoS performance in heterogeneous wireless communication networks environments. It is conducted by Central QoS Agents (CQA) and Access QoS Agents (AQA) to complete the whole mapping processes including:the information aggregation of local QoS, information registration of global QoS, building static QoS mapping on CQA nodes, sharing global QoS among CQAs and AQAs, establishing the dynamic QoS mapping by AQAs. This model mainly dealt with the problems of bigger differences in communication resources and quicker changing of QoS in heterogeneous wireless networks. It is also described formally in Z language and verified by formal tools. The simulated experimental results in OPNET environment show that it can improve the QoS with better performances.(3) This dissertation also proposed a key pre-sharing model based on one-way hash function and (t, n) threshold schema of Lagrange polynomial group to implement the security bootstrapping in Mobile Ad Hoc Networks (MANET) environment. This model involves following two phases including the pre-sharing keys based on one way hash function and Lagrange Interpolation Polynomial group and recovering the secure key based on the digital signature of threshold schema. The experiments on simulated environment were performed to validate the approach on the the performance of successful establishing secure link, computation complexity, the security of bootstrapping process, the capability of network recovery from compromised nodes and the network scale etc. The simulated experimental results show that this approach can harden the security of MANET environment with better performance.This dissertation proposed some novel and effective approaches to improve the security routing, QoS mapping and distributed authentication in heterogeneous wireless networks. Experimental results show that the proposed approaches have better performance in communication processes and it is so meaningful for practical environments.