Data Replication Algorithm Based On Stable Neighbor And Energy Prediction In Mobile Ad Hoc Networks

Mobile ad hoc network does not rely on fixed infrastructure. Due to the features such as self-organizing, rapidly deploying, environmental adaptability and survivability, it has a wide application in military battlefield communications, disaster relief, emergency rescue and other special circumstances. The data availability in mobile ad hoc is very low. As a key technique of data management and an important method to improve data availability and system performance, data replication has an important application in mobile ad hoc network.However, because of the movement characteristics and limited energy of nodes, the data replication technology in mobile ad hoc network faces new problems such as unstable neighbor and unbalance energy consumption. Therefore, stability prediction and energy prediction play an important role in replication algorithm. Our main works can be summarized as follows:Firstly, according to the edge movement of neighbors and the unfairness energy consumption, a replication algorithm named SNDR is proposed based on stable neighbors. SNDR algorithm analysis the stability of the link between node and neighbor and calculates the stability ratio, then gains the stable neighbors of node. In SNDR algorithm, node shares data with stable neighbors; it collects the weighted access frequency of stable neighbors and arranges the sum of access frequency in descending order. In order to select a right node to allocate the replica, the nodes that have the similar access frequency in addition consider node's residual energy, steady connection degree and free storage space in the placing process. In this way, SDNR can not only reduce the influence of the edge movement of neighbors but also balance the energy consumption between nodes. SNDR algorithm is implemented by network simulator NS2, the simulation experiment results show that in mobile ad hoc network, SNDR algorithm can effectively improve the rate of successful data access and balance the power consumption among nodes.Secondly, considering the situation that some data items become difficult to access after some nodes quickly exhaust the energy, a replica adjusting algorithm named EPRA is proposed based on energy prediction. When the residual energy of node is few, EPRA algorithm predicts the residual survival time of node by residual energy and the rate of energy consumption. If the residual survival time of node is short, EPRA algorithm judges the important data by the number of replicas within neighbors. In the copying process of important data, EPRA algorithm considers three situations that there are free storage spaces, there are other data's duplication, there are no free storage space and other data's duplication in neighbors, then select the right node to allocate the important data with the concern about access frequency, node's residual energy and connection degree. Simulation experiment results show that when partial nodes quickly exhaust the energy, EPRA algorithm can effectively improve the rate of successful data access.