Article

# Code division multiple-access techniques in optical fiber networks. I. Fundamental principles

Bell Commun. Res., Morristown, NJ
IEEE Transactions on Communications (Impact Factor: 1.75). 09/1989; DOI:10.1109/26.31181
Source: IEEE Xplore

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

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• ##### Article: Some Infinite Classes of Optimal (v, {3, 4}, 1, Q)-OOCs with {Q \in \{(\frac {1}{3}, \frac {2}{3}), (\frac {2}{3}, \frac{1}{3})\}}
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ABSTRACT: Variable-weight optical orthogonal code (OOC) was introduced by Yang for multimedia optical CDMA systems with multiple quality of service requirements. It is proved that optimal (v, {3, 4}, 1, (1/2, 1/2))-OOCs exist for some complete congruence classes of v. In this paper, for ${Q \in \{(1/3, 2/3), (2/3, 1/3)\}}$ , by using skew starters, it is also proved that optimal (v, {3, 4}, 1, Q)-OOCs exist for some complete congruence classes of v.
Graphs and Combinatorics 11/2013; · 0.35 Impact Factor
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##### Article: capacity analysis of asynchronous optical CDMA systems utilizing wrapped OPPM: multiple access interference limited case
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ABSTRACT: In this paper the capacity of asynchronous incoherent optical CDMA (OCDMA) systems employing wrapped overlapping pulse position modulation (WOPPM) for two types of receiver structures is analyzed. The analysis is performed in the presence of multiple access interference as the main limiting factor. Throughput analysis for uncoded systems utilizing WOPPM is conducted and a lower bound on the capacity for two types of correlator based receiver structures is derived. Furthermore, for a fixed code and a fixed maximum number of symbols, a numerical solution for maximizing the capacity is presented. Moreover, to minimize the probability of error when the throughput and the number of users are fixed, a numerical solution is introduced. Finally, for two common design problems, algorithms are proposed for achieving the system parameters well close to the optimal settings. The results of our different analyses for uncoded systems using WOPPM have been compared with unwrapped OPPM. Our results have also been compared with on-off keying (OOK) and pulse position modulation (PPM). The results of this work show that, for a fixed throughput, the performance of WOPPM is significantly superior to OOK and PPM.
Journal of Lightwave Technology 08/2013; 31(15):2613-2620. · 2.56 Impact Factor
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##### Article: Construction and generation of OCDMA code families using a complete row-wise orthogonal pairs algorithm
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ABSTRACT: A new code construction algorithm for incoherent Multi-Dimensional Optical Code Division Multiple Access (MD-OCDMA) for asynchronous fiber optic communication is proposed. We refer multi-dimensionality to two-dimensional (2D) wavelength–time or space–time domains and three-dimensional (3D) space–wavelength–time domains. The application of the algorithm in constructing 2D multiple pulses per row codes and 3D multiple pulses per plane codes is given. The performance of the codes is discussed. In the applications discussed, this construction ensures a maximum cross correlation of 1 between any two codes. The proposed codes have complete 1D code allocation, which increases the cardinality. The performance of some codes in literature is compared with the proposed codes. The analyzed performance measure is bit error rate due to multiple access interference for different numbers of active users. The performance analysis shows that the proposed 2D construction offers very low bit error rate at lower spectral efficiency when compared with other 2D constructions. A comparison of the proposed 3D construction with existing 3D constructions shows lower bit error rate for equivalent code dimension. New integrated optic designs for the generation of OCDMA codes using titanium indiffused lithium niobate technology are explored, which can enable compact encoders and decoders for computer communications.
AEU - International Journal of Electronics and Communications 05/2013; Vol.67:pp.868-874. · 0.55 Impact Factor