Optical CDMA network codecs with merged-M-coded wavelength-hopping and prime-coded time-spreading

This paper proposes a new hybrid code for optical CDMA systems based on modified maximal-length sequence (M-sequence) codes for wavelength-hopping and prime codes for time spreading. Using the proposed hybrid code, two optical encoder/decoders are constructed using either fiber-Bragg gratings (FBGs) and optical delay lines, or arrayed-waveguide gratings (AWGs) and optical delay lines, respectively. The system performance is compared with that provided by the well-known prime-hop sequence code. The results show that the merged-M-sequence codes not only provide a higher capacity, but can also be realized via a simpler configuration. Furthermore, the proposed code is less expensive than prime-hop code under virtually identical BER conditions.