Research On Handoff Decision Algorithms In Heterogeneous Wireless Networks

Seamless integration of different characteristics of the wireless network, user roaming between different networks, can get better service, which will be the inevitable trend of the future development of the communication system. Due to the various wireless technologies in coverage, bandwidth, business support, coupled with the new radio access technologies continue to emerge, how to realize the seamless switching between them is particularly critical. In-depth research in heterogeneous wireless network access selection algorithm for heterogeneous wireless networks fully integrated to provide important technical support, at the same time, it also has important significance for improving the network performance.Firstly, this thesis discusses the integration of heterogeneous wireless networks, vertical handoff technology, and common handoff algorithm and introduces the heterogeneous wireless network terminal protocol architecture and function, to achieve the design of a wireless heterogeneous network access model.Secondly the hierarchical structure of the heterogeneous wireless network of specific analysis. According to the traditional analytic hierarchy process (AHP) algorithm in the presence of defects and shortcomings, the introduction of more simple, objective of the three standard degree method to construct the comparison matrix, in order to reduce subjective thought has brought about. And the optimal transfer matrix to indirectly obtained the weight of various factors, to avoid the consistency test and adjustment of judgment matrix, to reduce the complexity of the algorithm. Simulation results validate the improvement of AHP algorithm with high accuracy and feasibility.Finally, a kind of improved close to the ideal scheme ordinal preference selection algorithm. In the traditional TOPSIS algorithm, the positive and negative ideal solutions are closely related to the number of alternative schemes. When the number changes, may reverse problem. To solve this problem, set a positive and negative ideal solution. When each scheme to the positive and negative ideal solution is equal to the distance, put forward the grey correlation analysis method and TOPSIS method combined by from various internal factors change trend and ideal scheme to sort. Simulation verified the improved TOPSIS algorithm is effective and has a high accuracy and reliability.