Optimizing the Waiting Time of Sensors in a MANET to Strike a Balance between Energy Consumption and Data Timeliness Oceans are important for scientific research and also for global economic and military security. Usually, wireless ad hoc networks are chosen to transform realtime data collected by ocean monitoring sensors (nodes). Due to the random motion of waves or the random direction of the wind, nodes in the network might become detached from the coverage of the network. In this case, the detached nodes can either send the collected data directly to the base station at the cost of consuming more energy or wait for a period of time to rejoin the network with the price of sacrificing the real time of the collected data. In this paper, we model the optimal waiting time for detached nodes before directly sending the data in the dynamic environment of ocean monitoring. For this purpose, we need to address two problems. The first is how to calculate the rate of coverage with a different number and different broadcast radii of nodes. The second is when a node detaches from the coverage of the network, how much time will it need to wait before it rejoins the network. We first establish the motion model of nodes, which is the basis to deduce the probability distribution of a certain time when the detached node rejoins the network. Based on the probability distribution, the waiting time of the detached nodes can be optimally determined, aiming to achieve a good balance between energy consumption and data timeliness. Finally, a series of simulations is conducted to validate the effectiveness of our proposed method.

CostEfficient Node Deployment for Intrusion Detection in Underwater Sensor Networks Underwater sensor network has broad application prospects for performing underwater warning, target detection, and marine environment monitoring. However, traditional cubefilled fullcoverage node deployment schemes are costly and infeasible to detect target objects due to the considerably redundant nodes. In this paper, we propose a new scheme with a low cost to detect the target in dynamic waters to reduce the cost of the deployment. Our scheme controls the distributed sensors to move and construct an angular sensor barrier through which the target may pass. The profilebased barrier deployment scheme only needs to adjust node depth to reduce movement costs. During depth adjustment, the proposed method takes the node density, the residual energy of the node and the node movement effect into account so that the randomly distributed nodes are sunk at different depths, and the redundant nodes are removed by the 2Voronoi diagram lemma. We use the simulation experiment to evaluate the coverage and energy consumption during the movement of the nodes. The analysis of the experimental results shows that the method has good coverage performance. Also, it can reduce and balance energy consumption during the anchor node deployment to extend network uptime.