Theoretical analysis of underwater simultaneous light Information and power transfer using inverted N parallel code shift keying with power splitting reciver

Underwater simultaneous light information and power transfer (USLIPT) has recently attracted attention for the efficient exploration and excavation of international seabed resources. In this paper,
$N$
parallel code shift keying (N-CSK), in which
$\mathrm{N}$
pseudo-noise (PN) codes are selected according to the transmitted signal, is adopted as a multiple-access scheme to study USLIPT with multiple access. In this paper, we propose an inverted N-CSK scheme to further improve the power-feeding performance of the USLIPT using N-CSK by constantly turning on
$M-N$
unselected LEDs, which are not used as transmit signals in N-CSK, to improve the power-feeding performance while maintaining the amount of information transmitted. The performance of the bit error rate (BER) and the power supply are evaluated by theoretical analysis. The results show that the power feeding performance degrades with decreasing
$N$
in N -CSK, but improves with decreasing
$N$
in the proposed scheme because the power feeding performance improves with increasing
$N$
. This is because, in the proposed method, the larger
$N$
is, the fewer the number of LEDs that are lit. However, no matter how large
$N$
is, the power-feeding performance of the proposed method is superior to that of N -CSK.