Design and Implementation of 3D Codes for Optical CDMA Systems

Abstract

newlineNumerous optical codes sets have been used in a typical OCDMA system where a newlinelarge number of optical codes are constructed using wavelength/time/space/polarization newlinedimensions to exploit the capacity of optical fiber. Among these codes, One-Dimensional newline(1-D) codes requires a larger code length to increase the number of code set whereas the newlineTwo-Dimensional (2-D) codes on the other hand provides a significant improvement in the newlinesize of code set without increment in its length. But the major challenge with 2-D codes is newlinethat as the number of codes increases there is a need of more lasers which ultimately increase newlinethe hardware complexity. It could be very well observed that the introduction of another newlinedimension can surely help to increase the code cardinality (number of codes) with improved newlinesecurity. The use of the third dimension will eventually provide more flexibility in the design newlineof codes which can help to accommodate large user base with better system performance. newlineIn the research work, a novel modified Three-Dimensional (3-D) multicarrier prime newlinecodes with space as the third dimension is proposed which can give enhanced security along newlinewith increased capacity. By adding this new dimension i.e. space, the optical signals can be newlinetransmitted over various modes which will not only increase the system security but also newlinemultifold the system capacity. In the proposed modified 3-D multicarrier prime codes, a newlinemathematical model has been developed based on rigorous analysis that can overcome a newlinelarge part of the limitations of the existing OCDMA system using 1-D and 2-D codes. Also newlinefor the purpose stated above, the available 1-D and 2-D optical prime codes and encoding newlinetechniques are studied, mathematically analyzed and simulated with a view to critically newlinevii newlineidentify their problems and limitations in terms of number of users, bit rate of the system, bit newlineerror rate, quality factor, required received power etc.