Low probability of detection for underwater acoustic communication

The ability to avoid detection of a communication signal in the underwater acoustic channel is extremely important for underwater acoustic communication (UWAC) systems when used for military-related applications. Furthermore, low probability of detection (LPD) may reduce environmental impact of UWAC as communication signals can be transmitted at lower power. In this paper, we study the LPD capability of UWAC systems. We consider an interceptor employing energy detector and calculate the minimal signal-to-noise power ratio (SNPR) which satisfies its required performance. For the receiver, we calculate the minimal required SNPR to allow reliable detection and decoding of a data packet using spread-spectrum signaling. We then analyze the LPD capability of the system for different channel and communication parameters.

I. Introduction

Underwater acoustic communication (UWAC) is used for various applications, such as exploring ocean resources or providing a gateway for sensor data [1]. UWAC is also used for sharing information between mobile devices such as autonomous underwater vehicles (AUVs), drifters such as gliders and underwater buoys, and human divers, each requiring either peer-to-peer or network communication capability. For military UWAC applications, covert communication is of interest such that the transmitter and receiver remain undetectable for a possibly nearby interceptor. Here, the objective is to achieve communication with a low probability of detection (LPD). LPD UWAC also reduces environmental impact of acoustic signaling. This is because LPD transmissions are low power and wideband and thus their effect on marine mammals is relatively smaller.