Performance analysis for UOWC transmission system using NRZ, AMI, and CSRZ modulation schemes

In this paper, three different modulation formats; namely non return to zero (NRZ), alternate mark inversion (AMI), and carrier compressed return to zero (CSRZ) are used in an underwater optical wireless communication (UOWC) system. A laser diode (LD) source operating at 532 nm is used. A comparison of transmission performance using these modulation schemes in the UOWC system are preferred in terms of received optical power, bit error rate (BER), Q-factor, and eye diagrams at 10 Gbps data rate. Additionally, real under-water environments such as pure sea (PS), clear ocean (CO), coastal sea (CS), harbor I (HI), and harbor II (HII) are considered. The simulation findings indicate that using the NRZ modulation scheme in UWOC system achieves the best performance, while the worst performance is observed when CSRZ is utilized. Further, the low attenuation caused by PS results in a longer underwater distance with higher received power and lower BER. At BER similar to 10(-9), and received power of similar to - 21 dBm, the underwater spans of 28 m for PS, 18.6 m for CO, 11.7 m for CS, and 4.06 m for HII are obtained when NRZ line coding is employed. Furthermore, at the same BER and received power, these underwater ranges are decreased to 26.3 m, 17.8 m, 11.3 m, and 3.96 m for PS, CO, CS, and HII, respectively, when CSRZ modulation format is used.

Automated summary

In this paper, the authors investigated the performance of three different modulation formats in an underwater optical wireless communication system. The results showed that the non return to zero modulation scheme achieved the best performance, while the carrier compressed return to zero modulation scheme performed the worst.