Débit binaire

Le débit binaire est une mesure de la quantité de données numériques transmises par unité de temps. Selon ses définitions normatives, il s'exprime en bits par seconde (bit/s, b/s ou bps) ou un de ses multiples en employant les préfixes du Système international (SI) : kb/s (kilobits par seconde), Mb/s (mégabits par seconde) et ainsi de suite. Dans le domaine de l'informatique, le débit est parfois exprimé en octets par seconde. Un octet équivaut à 8 bits, nombre de bits correspondant aux premières et aux plus simples des machines, et permettant de transmettre un caractère alphanumérique. On trouve aussi bien des notations ko/s (kilooctet par seconde) ou Mo/s que Bps (byte per second). Les notices anglophones abrègent byte en B majuscule pour le différencier du b de bit. Le byte est, en informatique, la plus petite unité adressable d'un ordinateur ; mais dans le domaine des télécommunications, le byte est toujours un octet. Utilisation Le débit binaire en « bit par seconde

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High Symbol Rate Coherent Optical Transmission Systems: 80 and 107 Gbaud

Luis Salamanca Miño, Rüdiger Urbanke

We demonstrate high speed optical transmission systems using digital coherent detection at all-electronically multiplexed symbol rates of 80 and 107 Gbaud. At 107 Gbaud, we demonstrate a single-carrier polarization division multiplexed quadrature phase shift keyed (PDM-QPSK) line rate of 428 Gb/s. At 80 Gbaud, we achieve a single-carrier line rate of 640 Gb/s using PDM 16-ary quadrature amplitude modulation (16-QAM). Using two optical subcarriers, we demonstrate a 1-Tb/s optical interface and conduct long-haul wavelength-division multiplexed (WDM) transmission on a 200-GHz grid over 3200 km of ultra-large effective area fiber.

Ieee-Inst Electrical Electronics Engineers Inc2014

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High Performance InP-Based Quantum Dash Semiconductor Mode-Locked Lasers for Optical Communications

Anthony Martinez

Several applications are pushing the development of high performance mode-locked lasers: generation of short pulses for extremely high bit rate transmission at 100 Gb/s and beyond, all-optical clock recovery at 40 Gb/s and beyond, generation of millimeter wave signals through mode-beating on a high speed photodiode, optical sampling for analog-to-digital conversion, and generation of wavelength-division-multiplexing channels. This paper will report on new advances in InP-based quantum dash mode-locked lasers, which largely surpass the performance of their bulk or quantum well counterparts in terms of the mode-beating spectral purity and the bandwidth of optical spectrum. In particular, we will describe the quantum dash nanostructures used for the mode-locked lasers and the dependence of the mode-locking properties on detailed quantum dash structures. We will demonstrate that these quantum dash lasers can be actively mode-locked, generating sub-picosecond or picosecond pulses at different repetition frequencies with extremely low timing jitter. They can also be used to achieve all-optical clock recovery, with timing jitter compliant with International Telecommunication Union (ITU) standards even for highly degraded input optical signal-to-noise ratio. Finally, we demonstrate that, owing to the very wide and flat optical spectrum and the low relative-intensity noise level of the mode-locked laser, error-free transmission over 50 km single mode fiber has been achieved for eight wavelength division multiplexing ITU channels at 10 Gb/s with a channel spacing of 100 GHz. (C) 2009 Alcatel-Lucent.

2009

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Performance analysis of dual-hop fixed-gain AF relaying systems with OSTBC over Nakagami-m fading channels

Serife Seda Kucur

In this paper, we present outage probability and symbol error rate (SER) performance analyses of a dual-hop transmission using fixed-gain amplify-and-forward relaying in flat Nakagami-m fading channels. The system under consideration is equipped with multiple antennas at source and destination adopting orthogonal space-time block coding to provide transmit diversity and maximum ratio combining to provide receive diversity, respectively. For integer and half-integer m values, closed forms of exact outage probability and moment generating function (MGF) expressions are derived through cumulative distribution function (CDF) of the overall system signal-to-noise ratio. Closed-form exact SER expressions based on the overall CDF are obtained for binary phase shift keying, binary frequency shift keying and M-ary pulse amplitude modulation. Exact SER expressions based on the MGF method are also obtained for binary differential phase shift keying, M-ary phase shift keying and M-ary quadrature amplitude modulation. Moreover, the asymptotic diversity order analysis is performed through derivations of asymptotic outage probability and SER. Theoretical analyses are validated by Monte Carlo simulations showing perfect match between each other. (C) 2012 Elsevier GmbH. All rights reserved.

Elsevier Gmbh, Urban & Fischer Verlag2012

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Compression de données

La compression de données ou codage de source est l'opération informatique consistant à transformer une suite de bits A en une suite de bits B plus courte pouvant restituer les mêmes informations, ou

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Disque Blu-ray

Le disque Blu-ray, ou Blu-ray Disc en anglais, avec comme abréviation officielle BD, est un format de disque numérique breveté et commercialisé à partir de 2006 par Sony permettant de stocker et res

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