Physical layer security for multihop underwater wireless optical communications using optical CDMA

For secure communications, the authors propose a underwater wireless optical communications code-division multiple-access (UOWC/CDMA) system with multiple relay assistance. Relay nodes employ the Chip Detect-and-Forward (CDF) technique to prevent the difficult multiuser decoding procedure. The proposed system performance, in terms of bit-error rate (BER) and transmission confidentiality, is analyzed in our study over fading channel.