Code Division Multiple-Access Techniques in Optical Fiber Networks—Part I: Fundamental Principles

Bell Commun. Res., Morristown, NJ
IEEE Transactions on Communications (Impact Factor: 1.99). 09/1989; 37(8):824 - 833. DOI: 10.1109/26.31181
Source: IEEE Xplore


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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    • "This is possible with simple reconfiguration of codes at the transmitters and receivers. Many implementations of fibre optic CDMA systems have been investigated and presented in the literature under the name of Optical CDMA in the last fifteen years [1] [2] [3] [4] [5]. "
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    DESCRIPTION: Evaluation of error probability based on the assumption that the gains of APDs used in upper and lower branches of optical code-division multiple-access (OCDMA) systems are matched provides an approximation which may in practice be an overestimate or underestimate of the actual probability of error. In this paper, we analyze the impact of APD mismatch in a synchronous OCDMA system based on the perfect difference codes (PDC). The results demonstrate that the performance degradation caused by the mismatch in branches, substantially degrades the bit error rate necessitating the requirement for close matching of the branches.
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    • "where x is the integer portion of the real value x [13]. "
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    ABSTRACT: In this paper, we characterize the performance of a relay-assisted underwater wireless optical code division multiple access (OCDMA) network over turbulent channel. In addition to scattering and absorption effects of underwater channels, we also consider optical turbulence as a log-normal fading coefficient in our analysis. To simultaneously and asynchronously share medium among many users, we assign a unique optical orthogonal code (OOC) to each user in order to actualize OCDMA-based underwater network. The most significant challenge in underwater optical communication is in the ability to extend the short range of its coverage. In order to expand the viable communication range, we consider multi-hop transmission to the destination. Moreover, we evaluate the performance of a relay-assisted point-to-point UWOC system as a special case of the proposed relay-assisted OCDMA network. Our numerical results indicate significant performance improvement by employing intermediate relays, e.g., one can achieve $31.5$ dB improvement in the bit error rate (BER) of $10^{-6}$ using only a dual-hop transmission in a $90$ m point-to-point clear ocean link.
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    • "There has been a growing interest in deploying the optical code division multiple access (OCDMA) technique for the next generation high-speed optical fiber networks [1] [2] [3] [4]. OCDMA is a promising technology since it offers several advantages in local area networks such as, high speed, huge bandwidth, bursty traffic, and simultaneous and asynchronous access with no waiting time through the assignment of unique signature sequences [3]. "

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