Design and simulation of 2D wavelength x time hybrid codes for OCDMA systems
Abstract
In recent years, Optical Code Division Multiple Access (OCDMA) has become
an interesting research area in optical communication technologies. Optical code
division multiple access is proposed as a natural solution to achieving asynchronous and high-speed connectivity in a local area network (LAN) environment. Optical CDMA is
shown to be competitive with other networking technologies such as F/WDMA and
TDMA, but has the benefit of more flexibility, simpler protocols, and no need for
centralized network control. OCDMA encoding or decoding process provides a high
level of security which is directly implemented in the physical layer. In OCDMA, type
of coding technique plays a major factor that influencing its performance. A new two
dimensional (2D) Wavelength x Time Hybrid code is proposed to enhance the capacity
and performance of the OCDMA system. 2D Wavelength x Time Hybrid code is
designed by using 1D Modified Double Weight (MDW) and 1D Flexible Cross
Correlation (FCC). These two codes are chosen because of capability to suppress
multiple access interference (MAI) and reduced the PIIN. The numerical results reveal
that the value of time spreading (spatial) code length, N is the major impact on the
cardinality of the system. The performance of the system can be enhanced by exploiting
the number of N rather than the value of wavelength encoding (spectral) code length, M.