Research On Several Key Technologies Of Cognitive Heterogeneous Wireless Networks

With the broadband development of mobile network and the mobility development of broadband networks, all-IP based heterogeneous networks coexistence and integration is becoming an important feature of next generation wireless networks. In the all-IP integrated ubiquitous networks, multiple network technologies exist. Various networks have various topologies, transmission rates, channel characteristics, network capacity, resource reservation method and scheduling and so on. How to meet the diversity and high quality of service requirements for next generation heterogeneous networks in the network architecture, traffic behavior model, network resource scheduling, network utility maximization and end-to-end QoS guaranteed seamless handover are the key technologies to realize the seamless integration of future heterogeneous wireless networks. The appearance of the cognitive network provides a new mentality and effective measure to solve the above problem.This paper firstly summarized the evolution and development tendency of heterogeneous wireless networks, then introduced and analyzed the cognitive radio and cognitive network technologies. Also the difficult problems for future cognitive heterogeneous networks were also addressed on.Considering the characters of heterogeneous wireless networks and cognitive networks, this paper proposed a new architecture for future cognitive heterogeneous wireless networks which we named CHNet. According to the user's QoS and changes in the external and network environment, through the reconfiguration of network parameters and intelligent cooperation between nodes, it can make real-time adjustments in order to protect the overall network performance and end to end demand of the service QoS. Based on the proposed architecture, this paper proposed a traffic model for cognitive heterogeneous wireless networks taking use of fuzzy logic. Simulation results proved that the proposed model can reflect the behavior of the network's traffic for the future complex networks, and support the research of other network technologies.According to the resource scheduling problem of complex heterogeneous wireless networks, this paper proposed a cross-layer adaptive cooperative scheduling scheme named CACS, which in the physical layer AMC techniques were used and in the data link layer HARQ technology was used, combined with cooperative transmission technology between heterogeneous wireless network access nodes. The proposed scheme can effectively improve the transmission quality of data services under the condition of non-reliable network, and increase utilization of network resource. In the same time, this paper also proposed the corresponding decision algorithm. Based on this algorithm, the system can take adaptive corresponding measures according to different network conditions. Simulation results proved that our proposed scheme can significantly enhance the network throughput and reduce the end to end delay and packet loss rate.In order to achieve the utility maximization of future cognitive heterogeneous wireless networks, this paper presented a complete distributed cross-layer design scheme named DCDS, taking full account of the distributed multi-hop wireless network protocol stack layers information, modeling network utility maximization problem, and taking use of the Lagrange dual decomposition method to decompose the optimization goal to joint optimization of the protocol layers. Simulation results show that the proposed optimization scheme can effectively improve the average network throughput and maximize the utility of the network.Considering the current development status and future cognitive development trend of heterogeneous wireless networks, this paper proposed an end to end QoS guaranteed cross-layer seamless handover scheme named CSHS, in which the underlying heterogeneous network-based differences were masked by taking use of MIH, a new intelligent vertical handover management unit VHM was introduced to complete discovery and handover decision, and a network layer protocol FMIPv6 was adopted to complete the implementation of the follow-up handover process. Comparing with MIH scheme, simulation results verified that the proposed scheme can not only effectively reduce the possibility of unnecessary vertical handover, but also reduce the handover delay and signaling overhead system, and completely avoid packet loss during vertical handover.Finally, the summary of the thesis was given. The shortcomings of the research were pointed out and some suggestions to the future research were listed.