In recent years, Underwater Acoustic Sensor Networks (UASNs) have gained considerable attention for their unique role in detecting and monitoring the underwater environment. However, due to the long propagation time, high bit error rate, and limited bandwidth of underwater acoustic systems, the design of media access control (MAC) protocols is extremely complex, especially for the power consumption of UASNs. Therefore, this paper proposes an energy-efficient MAC protocol for three-dimensional UASNs with time synchronization and power control (TDTSPC-MAC). The proposed protocol is a hybrid access scheme for three-dimensional UASN using techniques such as time synchronization, power control, clustering, layering, and sleep mechanisms. Moreover, the TDTSPC-MAC protocol uses the hierarchical concept and distributed clustering algorithm to divide the three-dimensional space, and combines time synchronization and power control strategies to avoid collisions. Besides, energy consumption is reduced through monitoring and sleep mode. Simulation results demonstrate that the proposed TDTSPC-MAC protocol has reasonable data transmission delay time, throughput, energy consumption, and other performance.
Before sensing and transmitting data, the underwater nodes need to calculate and estimate their location information through anchor nodes with known locations. The ranging-free positioning algorithm DV-hop can be applied to the underwater wireless sensor network in a relatively poor environment, which is not required high positioning accuracy. However, some anchor nodes may be destroyed and utilized to deter unknown nodes’ precise positioning in the underwater confrontation scenario. Therefore, we propose a computationally efficient algorithm for determining the location of sensor nodes in harsh and confrontational underwater environments and resisting non-cooperative network attacks. This algorithm integrates Nesterov accelerated gradient descent (NAG) into the DV-hop positioning algorithm and prunes the data by selecting the measurement inconsistency to get better positioning accuracy and higher security. The simulation experiment confirms that our proposed algorithm has better measurement accuracy in the underwater environment than the existing algorithms.
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