In the ultra-dense heterogeneous wireless network

the traditional vertical handoff algorithm can not describe the fuzziness and randomness of the network state at the same time

so the network performance can not be effectively improved. A vertical handoff algorithm based on the interval type II fuzzy neural network is proposed to solve above problem. A two-stage decision system is reconstructed: in the network’s prescreening stage

the historical access rate is defined to set the threshold combine with the number of current candidate network sets. According to the received signal strength and the remaining available bandwidth

all the networks within the user’s receiving range are preliminarily screened; The delay

packet loss rate and bit error rate of the remaining candidate networks are taken as the inputs of the it2fnn in the vertical handoff decision stage. The fuzzy logic reasoning is completed by using the structure of the feedforward neural network

and the output decision value is calculated after the training

and the optimal network is selected. The simulation results show that the algorithm can ensure low time consumption

and effectively reduce the error probability of handoff decision and the number of handoff failures and handoff times. Meanwhile

it can improve the total throughput of networks.