Information Capacity of Turbulent and Absorptive Underwater Wireless Link with Perfect Laguerre–Gaussian Beam and Pointing Errors

Abstract

The model of information capacity for underwater wireless optical communication (UWOC) links with pointing errors and the carrier of perfect Laguerre–Gaussian (PLG) beam in absorbed and weakly turbulent seawater is modeled. Using this model, the influence of channel parameters on the propagation of PLG beams is numerically analyzed. We show that the pointing error significantly reduces the performance of the optical transmission system. Large topological charge and radial orders are not conducive to high information capacity transmission. Additionally, the information capacity decreases with the increase in the spectral absorption coefficient of seawater. With higher transmission power, the transmission of an optical transmission system with high average capacity can be realized. The information capacity is affected by both signal wavelength and seawater absorption coefficient. That is, in the case of small seawater absorption and short message channel, the channel capacity loss of the link with long signal wavelength is smaller. In the case of long channels and strong seawater absorption, the influence of signal wavelength on the average capacity can be ignored. The information capacity of the communication link is the highest, which is composed of the carrier with the OAM topological charge, and the radial orders are both 1, and the wavelength is 410 nm.

Performance analysis of an underwater wireless optical communication link with Lommel beam

“…On the other hand, the BER rises as the receive aperture R increases in figure 7(a). The reason for this result is that the enlargement of R increases the total signal of OAM mode m 0 as well as the crosstalk of OAM modes m ≠m 0 in all channels, but the increment of the denominator in equation (11) is larger than that of the numerator, leading to an increase of the received crosstalk noise [22,43,44], hence degrading the quality of the communication. In figure 7(b), as the OAM channel number N increases, the amount of information transmitted by the communication link increases, so the average capacity of the system increases.…”

“…Considering the transmitter power and Gaussian white noise, the signal-to-noise-and-crosstalk ratio (SNCR) received by the receiver is defined as [22,43]…”

Propagation of perfect Laguerre–Gaussian entangled states in non-Kolmogorov atmospheric turbulence

“…It approximates more closely to an ideal PV beam than the SPV does. In addition, researches have been conducted on the performance of a PLG beam in wireless optical communication, and it has been found that PLG can outperform other perfect vortex beams [47][48][49]. The cylindrical wave function of the PLG beam can be expressed as:…”

Editorial for the Special Issue on Underwater Wireless Communications and Sensor Networks Technology

“…They validated that oceanic turbulence under salinity fluctuations and increased strength have adverse impacts on the OAM. Zhang et al [2] modeled the information capacity of UWOC links with pointing errors and the carrier of a perfect Laguerre-Gaussian (PLG) beam in weakly turbulent and absorbed seawater. Further, they numerically analyzed the impact of channel characteristics on the propagation of PLG beams.…”