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Mathematical Problems in Engineering
Volume 2015 (2015), Article ID 456829, 6 pages
Research Article

BER Analysis Using Beat Probability Method of 3D Optical CDMA Networks with Double Balanced Detection

1Department of Electrical Engineering, National Formosa University, Yunlin County 632, Taiwan
2Department of Electrical Engineering, Institute of Computer and Communication Engineering, National Cheng Kung University, Tainan 701, Taiwan

Received 16 September 2014; Accepted 7 January 2015

Academic Editor: Mo Li

Copyright © 2015 Chih-Ta Yen and Chih-Ming Chen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study proposes novel three-dimensional (3D) matrices of wavelength/time/spatial code for code-division multiple-access (OCDMA) networks, with a double balanced detection mechanism. We construct 3D carrier-hopping prime/modified prime (CHP/MP) codes by extending a two-dimensional (2D) CHP code integrated with a one-dimensional (1D) MP code. The corresponding coder/decoder pairs were based on fiber Bragg gratings (FBGs) and tunable optical delay lines integrated with splitters/combiners. System performance was enhanced by the low cross correlation properties of the 3D code designed to avoid the beat noise phenomenon. The CHP/MP code cardinality increased significantly compared to the CHP code under the same bit error rate (BER). The results indicate that the 3D code method can enhance system performance because both the beating terms and multiple-access interference (MAI) were reduced by the double balanced detection mechanism. Additionally, the optical component can also be relaxed for high transmission scenery.