NAPR: A node activity-based probabilistic routing algorithm in Delay Tolerant-Mobile Sensor Networks

In the probabilistic routing algorithms of DT-MSN (Delay Tolerant-Mobile Sensor Networks), packet delivery only depends on the probability of transmitting to its destination node. The prediction of probability is not reasonable because of not considering every node´s activity level. In this paper, by mixing a node activity factor into the prediction of delivery probability, we propose a Node Activity-based Probabilistic Routing algorithm (NAPR). First, a physical quantity denoted by node activity is introduced to indicate the nodes´ active level in the network. The proposed algorithm takes the encountering records and the nodes´ active level into consideration. Second, by using parameter α to weigh the original probabilistic factor and the active level factor, a new weighted average value serves as a packet Delivery Predictability (DP). Nodes will compare the DP to decide whether the packet is delivered and the change of weighted factor α will have an impact on the relationship between nodes´ active level factor and DP. Besides, NAPR adopts the TTL (Time To Live)-based discarding strategy to manage nodes´ buffer space. Simulation results show that NAPR improves the DP and delivery ratio of packets and shortens the average delivery delay. Meanwhile, the number of packet copies and overhead ratio decreases accordingly.