Research On Virus Propagation Model And Stability Of Mobile Ad Hoc Network

For the past few years, the mobile ad hoc networks, which consist of short-distance wireless devices, are massively utilized in a variety of fields such as commercial or military areas (e.g., historic preservation, space exploration, military reconnaissance etc). However, it is hard to construct a reliable security mechanism in MANETs on account of limited resources (e.g., the storage space, battery capacity, communication radius) of nodes and time-vary topology in response to the mobility of nodes. Therefore, the network security has received much concern and become a focus of researchers’ attention. At present, most researches on MANETs focus on routing algorithms, security authentication etc. These researches are effectively helpful to protect the inner networks form malicious attacks coming from the external networks, but are helpless if attacks occur in the inner networks, for example, worm attacks. Once the worm and other malicious viruses are widely spread in the network, the network will be temporarily or even permanently disabled, owing to the severe exhaustion of node limited battery resources or the serious damage of node core hardware. As a result, it is absolutely essential to research more about the epidemic dynamics on MANETs.In this paper, we will focus on epidemic dynamics on MANETs. As we known, the network topology varies over time on account of the intermittent mobility of nodes, and thus the epidemic propagation will be influenced by the mobility style (e.g., velocity, direction, communication radius etc.). So our first issue is to address how to integrate these factors into the epidemic propagation models. Moreover, since the most previous studies consider that security patches cannot be disseminated in a short time over MANETs for its’frequent variation of topology, the pulse vaccination on MANETs has been seemed unrealistic and never been studied. However, there is no doubt that security patches can be broadcast to other nodes through the base station or cluster nodes. While other nodes receive and install those latest patches, the inner security mechanism will take effects immediately. As a result, a massive number of infected nodes will recover almost synchronously. Consequently, it is essential to research on the pulse vaccination on MANETs. At last, as the mean field theory (MFT) cannot reflect the mobility varieties of individual node and the mobility complexity in a realistic situation well, an epidemic propagation model on MANETs based on cellular automata is proposed to study the relationship between the individual mobility varieties and the epidemic propagation.Above all, our research work about the epidemic propagation on MANETs can be divided into three parts as follows:(1) The epidemic propagation model based on MFT. Consider the transfer relationship of node states, and impacts of communication radius, moving velocity on epidemic propagation, we propose an epidemic propagation model on MANETs based on differential equations. The stability and bifurcation theory of nonlinear system is used to analyze the propagation dynamics and epidemic extinction thresholds after figuring out the equilibrium points and their stability of our proposed equations.(2) The impulsive epidemic propagation model based on MFT. Consider realistic feasibilities of pulse vaccination, we propose a pulse vaccination epidemic propagation model on MANETs based on differential equations. The stability theory of IDE is utilized to analyze our proposed models. Based on this, we not only obtain the epidemic-free periodic solution and its stability, but also work out the viral persistence condition. Above all, we further analyze the propagation dynamics and thresholds of viral extinction.(3) The epidemic propagation model based on cellular automata (CA). Consider the mean field theory cannot reflect the mobility varieties of individual node and the mobility complexity in a realistic situation well enough. We propose a four random tuples mobility model, and the propagation model is established to study the relationship between mobility varieties and epidemic dynamics based on CA.