Emerging OCDMA communication systems and data networks [Invited]

Salehi, Jawad A.

doi:10.1364/jon.6.001138

Cited by 76 publications

(31 citation statements)

References 146 publications

(304 reference statements)

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“…The spectrum spreading techniques have been typically implemented in fibreoptic and optical wireless networks [5] using OOCs; other sequences as those described in [6][7][8] or 2 n prime codes [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Code acquisition of random optical codes in optical code-division multiple-access

Martín-González¹,

González²,

Poves³

et al. 2012

IET Commun.

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In this study, the authors present a technique for code acquisition in optical code-division multiple-access systems using the recently introduced random optical codes. In these systems, the communication is divided in two parts: a synchronisation process and the data transmission. The main target of the study is to describe and analyse the new algorithm of synchronisation using Markov processes. Once described the code acquisition technique and established an estimation for the probability of false alarm (FA) of the proposed scheme, two different proposals for the optimisation of the code parameters are described. They are based on two different estimators for the probability of FA. The first one considers the expected value for the probability of FA. The second one is very much restrictive. It guarantees that the probability of FA is in a confidence interval. It takes the upper bound of the confidence interval as estimator for the probability of FA. Although the second one presents worse acquisition time, the authors consider that the gain provided by the first method is not sufficient enough to assume its loss in the reliability. Thus, the authors propose to guarantee the probability of FA in a confidence interval. A compromise between reliability and acquisition time is obtained with this second method.

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Section: Introductionmentioning

confidence: 99%

Code acquisition of random optical codes in optical code-division multiple-access

Martín-González¹,

González²,

Poves³

et al. 2012

IET Commun.

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“…Optical CDMA systems have become an alternative multiple access for fiber optics and optical wireless systems [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

A review on synchronous CDMA systems: optimum overloaded codes, channel capacity, and power control

Hosseini

Javidbakht

Pad

et al. 2011

J Wireless Com Network

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This paper is a tutorial review on important issues related to code-division multiple-access (CDMA) systems such as channel capacity, power control, and optimum codes; specifically, we consider optimum overloaded codes that achieve errorless transmission in the absence of noise for the binary and nonbinary cases. A survey of lower and upper bounds for the sum channel capacity of such systems is given in the presence and absence of channel noise. The asymptotic results for the channel capacity are also investigated. The channel capacity, errorless transmission codes, and power estimation for near-far effects are also explored. The emphasis of this tutorial review is on the overloaded CDMA systems.Keywords: Code Division Multiple Access (CDMA), Optimum codes, channel capacity bounds, near-far effects, power control I Introductioncode-division multiple access (CDMA) has been the most important multiple access technology for the 3rd generation GSM and American Cellular systems [1]. Optical CDMA systems have become an alternative multiple access for fiber optics and optical wireless systems [2][3][4].In CDMA systems, each user is assigned a unique code signature that consists of a number of chips. The signature length (also called chip rate) is defined as the number of chips in each signature code. Each user signature is multiplied by the respective data, and the transmitted vectors are added up in the common channel. The resultant vector is then observed at the received user end. In order to decode the received signal, the detector of the received user should know its own unique signature. These codes should be designed such that the cross-correlations between the code of the desired user and the codes of the other users are minimal.For the wireless case, the most well-known binary (Endnote a) code for the synchronous case is Hadamard orthogonal code that is appropriate for fully and underloaded CDMA systems. (Endnote b) But because of bandwidth limitation in the communication systems, we are interested in finding codes that can support more users than the chip rate (overloaded case). In the overloaded case, we cannot use Hadamard codes; Even random codes create interference that cannot be eliminated completely [5][6][7]. Optical orthogonal codes (OOC) [3,8] are not really orthogonal; however, using interference cancelation, we can remove interference completely. Most of the research in the overloaded case is related to code design and multi-access interference (MAI) cancelation in order to decrease the probability of error. Examples of these types of codes are pseudo random spreading [9,10], Welsh Bound Equality (WBE) codes with minimal total square correlation (TSC) [11][12][13][14], OCDMA [15][16][17], Multiple-OCDMA [18], and PN/ OCDMA [19] signature sets. None of the above codes guarantee errorless transmission in the absence of channel noise for overloaded CDMA systems. There are also some codes that are not designed upon cross-correlation and are designed such that they can provide one-to-one transfor...

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“…Signature sequences as optical orthogonal codes (OOCs) [3]- [6], prime sequences [7]- [9] or 2 n prime codes [10]- [12] have been used in OCDMA systems. Recently, Salehi has revised many of these codes used in OCDMA systems in [13]. There, it is highlighted how the multiple-access interference (MAI) effect reduction has been deeply studied in the literature [14]- [18].…”

Section: Introductionmentioning

confidence: 99%

Algorithm Optical Codes: An alternative to Random Optical Codes in an intra-satellite optical wireless network

Martín-González¹,

Poves²,

Hernández³

2008

2008 10th Anniversary International Conference on Transparent Optical Networks

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We propose a novel family of optical codes to be used in intra-satellite optical wireless networks. They are Algorithm Optical Codes (AOCs). This family is related with the recently introduced family Random Optical Codes (ROCs). Both families of codes are designed to be used in optical Code-Division Multiple-Access (OCDMA) systems. Similarly than their predecessor, i.e. ROCs, AOCs are specially suitable for optical networks where the number of channels varies, ever large, low bit rate requirements, energy limitations and packed data are presented. For example sensor networks demand these requirements.A detailed description of AOCs is shown in this paper. Furthermore a comparison between them and ROCs is presented. We find that AOCs provide less probability of error than ROCs, for a given length of the code and a number of users. Moreover a system using AOCs can change the length of the code easier than a system using ROCs. This fact permits a more efficient accommodation to the actual number of users.Finally the implementation in an intra-spacecraft Telecommand and Telemeasurement (TC/TM) optical wireless network is also described. We compare the families in the intra-spacecraft optical wireless network.

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Emerging OCDMA communication systems and data networks [Invited]

Cited by 76 publications

References 146 publications

Code acquisition of random optical codes in optical code-division multiple-access

Code acquisition of random optical codes in optical code-division multiple-access

A review on synchronous CDMA systems: optimum overloaded codes, channel capacity, and power control

Algorithm Optical Codes: An alternative to Random Optical Codes in an intra-satellite optical wireless network

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