Code division multiple-access techniques in optical fiber networks. I. Fundamental principles
ABSTRACT An examination is made of fiber-optic code-division
multiple-access (FO-CDMA), a technique in which low information data
rates are mapped into very-high-rate address codes (signature sequences)
for the purpose of achieving random, asynchronous communications free of
network control, among many users. The need for a special class of
signature sequences to achieve the multiple-access capability using
fiber-optic signal processing techniques is discussed. A class of
signature sequences called optical orthogonal codes (OOCs) that provide
the auto- and cross-correlation properties required for FO-CDMA is
introduced and used in an experiment to show the principles of FO-CDMA.
The experiment demonstrates the auto- and cross-correlation properties
of the codes. The concept of optical disk patterns, an equivalent way of
representing the OOCs, is introduced. The patterns are used to derive
the probability density functions associated with any two interfering
OOCs. A detailed study of different interference patterns is presented,
and the strongest and the weakest interference patterns are determined
- SourceAvailable from: S. A Aljunid[Show abstract] [Hide abstract]
ABSTRACT: In this paper, we have extensively analyzed the SAC-OCDMA system performance using Modified Double Weight (MDW) code with NAND detection technique as newly developed by the authors. In theoretical analysis, various noises and Multiple-Access Interference (MAI) effect were taken into account. The system performance was characterized by the signal-to-noise ratio (SNR) and the Bit-Error-Rate (BER). The analysis results obtained with NAND detection technique were compared with those as obtained with complementary subtraction techniques. The comparison results revealed that the NAND detection technique with MDW code can support more number of active users and improve the system performance compared with complimentary subtraction techniques. We also ascertained by simulation experiment that the BER performance of the system with NAND detection technique is greatly improved as compared to the complementary subtraction technique. Key words: Optical code division multiple access (OCDMA), NAND/complementary detection, modified double weight (MDW) code, multiple-access interference (MAI).
- Journal of Communications. 01/2014; 9(2):99–106.
- Journal of optics 09/2014; · 2.01 Impact Factor