A Fuzzy Set Based Dynamic Trust Model for Heterogeneous Wireless Networks

The integration of various wireless networks brings some new access security challenges in heterogeneous wireless networks (HWNs). Transaction of the mobile host with an unknown network is more a norm than an exception. This paper proposes a trust management mechanism and a fuzzy set based dynamic trust model (FBDTM) to evaluate the trustworthiness of the network in HWNs. In the model, trust is a measure of information imprecision which can be measured by membership degrees to different fuzzy sets. The evaluation incorporates direct trust, recommendation trust, reputation of recommenders and time stamp. Direct and recommendation trusts reflect how well the network has fulfilled the service agreement in the past. By introducing reputation of recommenders, malicious behaviors of the dishonest entities are restrained effectively. Time stamp makes the evaluation pay much attention to the most recent performance records. Based on the trustworthiness, the mechanism helps mobile host make a decision on the access network selection. The simulation results show the FBDTM model can accurately evaluate the trustworthiness of the network and effectively restrain the acts of slander and co-fraud.