| When natural disasters,public emergencies,large-scale events,terrorist attacks happen,the traditional communication network is unable to meet the needs of the communication for dispatching at the scene.Timely capabilities to command rescue which put forward higher requirements to the special network communication.Therefore,special network communication technology has trend to develop to be digital,broadband,integrate.In the heterogeneous convergence architecture of the special communication network,better user experience and network performance are required to multimode terminals connected to the network in order to deal with emergencies anywhere and anytime.Vertical handover technology is an important component of mobility management technology among them.Based on the police digital trunking narrowband network and long term evolution broadband network as the representative of the converged network scenarios,this paper focus on the mobility management issues of the heterogeneous convergence network,the optimization of handover performance is achieved due to in-depth study of the algorithm in the vertical handover process.Based on the comparison and analysis of existing research results,a scheme for multiattribute decision-making vertical handover algorithm based on terminal battery power is designed in order to reduce unnecessary resource consumption of the handover process while maximizing the use of the network resource.In the process of handover,network interface adaptively opened to find the available network at first in this paper.And then subjective and objective are combined to dynamically acquire weight and followed by the use of technique for order preference by similarty to ideal solution to select the best network.Finally the network load balancing feature and service type is considered to determine the handover.In addition,giving the uncertainty factors of the network,a vertical handover strategy based on fuzzy logic is proposed.Firstly,a speed adaptive network discovery strategy is proposed,and then the gray level prediction is carried out according to the received signal strength to reduce the fuzzy logic processing,and then use the fuzzy logic to deal with multiple types of parameter,and the optimal candidate network is determined according to the network evaluation value.At the same time,the vertical handover process of the strategy is analyzed and the optimal handover network is obtained.Finally,using simulation to evaluate the performance of the proposed vertical handover algorithm.The simulation results show that the improved two algorithms can handover of the most suitable network according to the group prior characteristics and the QoS of different service types.At the same time,the number of unnecessary handover and the complexity of the algorithm is both reduced,and the success ratio of handover and overall network loads balancing is improved greatly. |
