Vapor Cloud Delayed-DPPM Modulation Technique for nonlinear Optoacoustic Communication

TL;DR

This paper introduces the vapor cloud delayed-DPPM modulation technique to enhance data rate and power efficiency in nonlinear optoacoustic underwater communication, overcoming vapor cloud formation issues associated with high-power lasers.

Contribution

The paper proposes a novel VCD-DPPM modulation method that significantly improves data rate and power efficiency over traditional OOK in optoacoustic communication systems.

Findings

VCD-DPPM achieves approximately 6.9 times higher symbol rate than OOK at 10 kHz laser repetition.

VCD-DPPM is 137% more power efficient than OOK.

Simulation results show VCD-DPPM enables efficient data transmission at various depths and noise conditions.

Abstract

The optoacoustic process can solve the longstanding challenge of wireless information transmission from an airborne unit to an underwater node (UWN). The nonlinear optoacoustic signal generated by proper laser parameters can propagate long distances in water. However, forming such a signal requires a high-power laser, and the buildup of a vapor cloud precludes the subsequent acoustic signal generation. Therefore, pursuing the traditional on-off keying (OOK) modulation technique will limit the data rate and power efficiency. In this paper, we analyze different modulation techniques and propose a vapor cloud delayed-differential pulse position modulation (VCD-DPPM) technique to improve the data rate and achieve high power efficiency for a single stationary laser transmitter. The symbol rate of VCD-DPPM is approximately 6.9 times and 1.69 times higher than OOK in our text communication simulation using a laser repetition rate of 10 kHz and 40 Hz, respectively. Furthermore, VCD-DPPM is 137% more power efficient than the OOK technique for both cases. We have generated different acoustic signal levels in laboratory conditions and simulated the bit error rate (BER) for different depths and positions of the UWN, while considering ambient underwater noises. Our results indicate that VCD-DPPM enables efficient data transmission.