Impact of mobility on trust decay rate

In trust-based models for MANETs, it is often assumed that the trust value between two nodes decays proportional to the time these nodes are out of transmission range of each other. We present in this paper an analysis of the trust decay rate for some general networking and trust computation models. Our analysis allows for the consideration of the subjective trust values assigned by present and past neighbours within a given history timeframe. The mobility models being studied in this paper include random way point (RWP) and random walk (RW). This analysis exhibits the impact of mobility on the trust decay rate. Simulations are used to confirm the accuracy of analytical results and shed light on some interesting facts such as the slow decay of globally computed trust values, even if fast subjective trust decay functions (linear and exponential) are employed, or the weak impact of the network density on the trust decay rate.