水下安全监测无线磁感应通信3D路径损耗

Wireless magnetic-induction communication 3D path loss for underwater safety monitoring

为有效避免声信号在浅海水域受海底海面多次反射的影响,针对水下安全监测网络节点方向、位置变化的特点,以无线磁感应通信技术为通信手段,在对单向无线磁感应通信模型分析的基础上,提出了一种全向水下无线磁感应通信模型.研究结果表明:在单向无线磁感应通信模型下,接收天线法向量方向角度γ为0.5π与1.5π时,收发天线之间耦合作用消失,导致收发端无法保持正常通信.在海水环境中,由于涡流效应造成无线磁感应通信的额外损耗分别与信号频率和海水盐度的平方根成正比关系,当天线线圈半径为0.5 m,匝数为100时通信距离仅为20.0 m;在淡水环境下采用全向无线磁感应通信模型,当接收天线位置和方向变化时,其路径损耗在60～67 dB的范围内变化,能够有效解决单向通信模型中由于天线方向、位置的变化造成的通信中断问题,提高通信的可靠性,为水下安全监测网络的应用提供参考.

To avoid the multiple reflections of safety acoustic signals between seabed and surface effectively, wireless magnetic-induction communication technology was used as the communication mean. For the changes of the orientations and positions of the nodes in underwater safety monitoring networks, a model of omnidirectional wireless magnetic induction communication was proposed based on the studies of the unidirectional wireless magnetic induction communication. The results show that in the model of unidirectional wireless magnetic induction communication, the transmitter is not able to communicate with the receiver when the angle of the receiving antenna’s normal vector is equal to 0.5π and 1.5π, because the coupling between the transmitting and receiving antennas disappears. The extra loss caused by the eddy current effects is proportional to the square root of the seawater salinity and the signal frequency separately, as a result, the communication range is only 20.0 m when the radius of antenna coil with 100 turns is 0.5 m. The path loss of omnidirectional wireless magnetic induction communication model varies from 60 to 67 dB during the process of the changing of the receiving antenna’s position and orientation in fresh water environment, which can effectively solve the communication interruption caused by changes of unidirectional antenna’s position and orientation, and provide reference for the application of underwater safety monitoring networks.