Optical Fiber Code Division Multiple Access Networks: A Review

Karafolas, Nikos; Uttamchandani, Deepak

doi:10.1006/ofte.1996.0017

Cited by 55 publications

(24 citation statements)

References 112 publications

(157 reference statements)

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“…Much like wireless and wired communication networks, the agile pixel can operate in different programmable time-frequency coding modes like Frequency Division Multiple Access (FDMA), Code-Division Multiple Access (CDMA), and Time Division Multiple Access (TDMA) [22], [24]- [26]. CDMA and FDMA will produce spread spectrum RF signals from the PD while TDMA is the staring-mode operation of the CAOS imager, one agile pixel at a time producing a DC signal.…”

Section: Proposed Caos Imager Designmentioning

confidence: 99%

Coded access optical sensor (CAOS) imager

Riza

Amin

Torre

2015

J. Eur. Opt. Soc.-Rapid Publ.

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High spatial resolution, low inter-pixel crosstalk, high signal-to-noise ratio (SNR), adequate application dependent speed, economical and energy efficient design are common goals sought after for optical image sensors. In optical microscopy, overcoming the diffraction limit in spatial resolution has been achieved using materials chemistry, optimal wavelengths, precision optics and nanomotion-mechanics for pixel-by-pixel scanning. Imagers based on pixelated imaging devices such as CCD/CMOS sensors avoid pixel-by-pixel scanning as all sensor pixels operate in parallel, but these imagers are fundamentally limited by inter-pixel crosstalk, in particular with interspersed bright and dim light zones. In this paper, we propose an agile pixel imager sensor design platform called Coded Access Optical Sensor (CAOS) that can greatly alleviate the mentioned fundamental limitations, empowering smart optical imaging for particular environments. Specifically, this novel CAOS imager engages an application dependent electronically programmable agile pixel platform using hybrid space-time-frequency coded multiple-access of the sampled optical irradiance map. We demonstrate the foundational working principles of the first experimental electronically programmable CAOS imager using hybrid time-frequency multiple access sampling of a known high contrast laser beam irradiance test map, with the CAOS instrument based on a Texas Instruments (TI) Digital Micromirror Device (DMD). This CAOS instrument provides imaging data that exhibits 77 dB electrical SNR and the measured laser beam image irradiance specifications closely match (i.e., within 0.75% error) the laser manufacturer provided beam image irradiance radius numbers. The proposed CAOS imager can be deployed in many scientific and non-scientific applications where pixel agility via electronic programmability can pull out desired features in an irradiance map subject to the CAOS imaging operation.

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Section: Proposed Caos Imager Designmentioning

confidence: 99%

Coded access optical sensor (CAOS) imager

Riza

Amin

Torre

2015

J. Eur. Opt. Soc.-Rapid Publ.

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“…Recently, optical code division multiple access (OCDMA) technique is getting more attractive due to its several features as its ability to support asynchronous access, bursty traffic, secure transmission and effective cost [1,2]. The main drawback of OCDMA is that its performance and capacity are limited by multiple access interference (MAI) [3,4].…”

Section: Introductionmentioning

confidence: 99%

SAC- OCDMA System Using Different Detection Techniques

Somaya¹,

Mottaleb²,

Fayed³

et al. 2014

IOSRJECE

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:In this paper, we investigate the optimum received power for spectral amplitude coding optical code division multiple access (SAC-OCDMA) INTRODUCTIONRecently, optical code division multiple access (OCDMA) technique is getting more attractive due to its several features as its ability to support asynchronous access, bursty traffic, secure transmission and effective cost [1,2]. The main drawback of OCDMA is that its performance and capacity are limited by multiple access interference (MAI) [3,4]. Researchers proposed spectral amplitude coding (SAC) from all types of OCDMA due to its ability in restrain MAI when using a suitable detection technique at the receiver with fixed in-phase cross correlation codes [5]. Low cost broadband sources such as light emitting diodes (LEDs) can be used for SAC-OCDMA system. However, the performance of SAC-OCDMA is still limited by phase induced intensity noise (PIIN) that results from using broadband light sources [6]. Modified-AND subtraction detection technique and SPD detection technique are used for reducing PIIN and MAI [7].In this work, enhanced double weight codes (EDW) are used as the signature codes for SAC-OCDMA systems with modified-AND subtraction detection and SPD detection techniques when APDs are used.The remainder of this paper is organized as follows. In Sec 2, we give a detailed explanation about the detection techniques, followed by the network simulation setup in Sec.3. Section 4 is devoted for the results and discussion. Finally, the conclusion of the paper is provided in Sec.5. II. DETECTION TECHNIQUES 2.1 MODIFIED-AND SUBTRACTION DETECTIONThe SAC-OCDMA receiver diagram of this technique is shown in Fig. 1 [7]. The received optical signal is split by splitter 1 into two parts, one to the upper decoding branches and the other to the AND decoder through an attenuator. The attenuator ensures that, the interference signal has an equivalent power incident on each photo detector in the case of an inactive user. The decoder filters are placed in a parallel configuration. This structure divides the spectrum of the decoded signals. It is worth to note that, both splitters (1 and 2) and the attenuator could be replaced by a single coupler with an appropriate coupling ratio in order to get a more cost-effective receiver. The decoder has a spectral response matched to the active user, whereas the AND decoder has overlapped bins from different interferers. These overlapped bins can be represented mathematically by AND operation between the active user and interferers [8]. This technique can be performed using the inexpensive fiber Bragg-gratings (FBGs) to decode the received signal because of their low insertion losses, good spectral resolution, small size, and light weight [10]. The photo detector is composed of two photodiodes (PD and s-PD) which are connected electrically in opposition. The output signal is proportional to the power difference of the two optical inputs. In the presence of an interferer, the difference between the two signals is cancelled o...

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“…These systems also require optical summation that causes considerable losses [7]. Ladder networks are introduced to reduce the splitting loss problem [8]- [11], but the encoder/decoder design limits the number of different codes that could be generated. Coherent systems are also proposed; they allow the use of bipolar codes that can be designed in such a way that some or all of the multiple access interference (MAI) can be cancelled [12]- [17].…”

Section: Introductionmentioning

confidence: 99%

Design and analysis of a dynamic code division multiple access communication system based on tunable optical filter

Hamarsheh

Shalaby²,

Abdullah

2005

J. Lightwave Technol.

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Abstract-A dynamic optical code division multiple access (DOCDMA) communication system is proposed for high-bandwidth communication systems. An implementation of the system is proposed based on a fast tunable optical filter (TOF) in each encoder and decoder. This technique actively modulates the central wavelength of a TOF according to a functional code at the transmitter during the bit period before the transmission of the data. The system is modeled and analyzed taking into account multiple access interference (MAI), thermal noise, and phase-induced intensity noise (PIIN). The performance of this system is compared to that of a spectral amplitude coding system that uses either a Hadamard code or a modified quadratic congruence (MQC) code. The results show that the proposed DOCDMA system reduces the PIIN effect on the performance of the system and improves the bit error rate (BER) performance at a large number of users. Furthermore, it is found that when the effective power is large enough, the MAI becomes the main factor that limits system performance, whereas when the effective power is relatively low, both thermal noise and PIIN become the main limiting factors with thermal noise having the main influence.Index Terms-Multiple access interference, optical code division multiple access (CDMA), optical fiber communication systems, spectral amplitude coding.

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Optical Fiber Code Division Multiple Access Networks: A Review

Cited by 55 publications

References 112 publications

Coded access optical sensor (CAOS) imager

Coded access optical sensor (CAOS) imager

SAC- OCDMA System Using Different Detection Techniques

Design and analysis of a dynamic code division multiple access communication system based on tunable optical filter

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