Using Distributed MIMO Sonar and Time Delay Matching to Localize Underwater Target in Shadow Zone of Deep Ocean

For the target located in the shadow zone of deep ocean, traditional single-node active localization method can utilize the bottom bounce mode in conjunction with time delay matching to realize target localization. However, the localization result fluctuates severely caused by channel fluctuations in the shadow zone of deep ocean. To solve this problem, this paper proposes an underwater target localization method using a distributed MIMO sonar with time delay matching in deep ocean environments. Distributed MIMO sonar can explore multi-angle illuminations of a target and obtain the so-called spatial diversity gain to suppress the channel fluctuation. By using the distributed MIMO sonar structure, we place a group of active nodes at various positions and construct a cost function which is the matching result of target's time delays extracted from all active nodes. Numerical simulations validate that the proposed method can produce a robust target localization result than the traditional active localization method using only one node.