研究目的

To provide an overview of time-reversal (TR) communications in both shallow and deep water, including recent advances such as bidirectional equalization, multiuser communications with mobile users, and communication with a glider serving as a mobile gateway.

研究成果

The paper concludes that TR communications first proposed in the early 2000s have evolved substantially over the last decade as an alternative to conventional multichannel equalization (M-DFE). TR exploits spatial diversity to achieve spatial and temporal focusing, directly applicable to communications in complex ocean environments. The block-based TR-DFE has been demonstrated successfully in both shallow and deep water for various frequencies with different bandwidths and distances, exploiting spatial or temporal diversity or both and achieving a high spectral efficiency.

研究不足

The paper discusses the technical and application constraints of the experiments, as well as potential areas for optimization. It mentions the challenges of implementing active TR due to the requirement of a number of transducers that can both receive and transmit signals, and the considerable lapse of time between the reception of the probe source signal and retransmission of a communication message composed at TRM, allowing for the channel/environment to vary and potentially violate the stationarity assumption.