Rapidité de modulation

Résumé

Dans un canal de communication utilisant une méthode de transmission par éléments temporels discrets, dont les canaux de communication numériques, la rapidité de modulation, aussi appelée « vitesse de modulation », est l'inverse de la plus courte durée théorique de l'élément de signal. Dans la plupart des canaux numériques, les éléments de signal ou symboles sont de durée égale, et la rapidité de modulation est le nombre de moments élémentaires de signal par unité de temps. La rapidité de modulation est alors également appelée débit de symbole. Elle se mesure en baud. Le débit binaire, qui est la quantité d'unités d'information que transmet le signal par unité de temps, est le produit de la rapidité de modulation par le logarithme binaire de la valence de l'élément. : d = r * log2(v) où v est la valence. Exemples :

Si un élément de signal ne peut avoir que deux valeurs, alors log2(v) = log2(2) = 1 et le débit binaire est égal à la rapidité de modulation.
La télévision numériq

Source officielle

https://fr.wikipedia.org/wiki/Rapidit%C3%A9_de_modulation

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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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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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26.3 A pin- and power-efficient low-latency 8-to-12Gb/s/wire 8b8w-coded SerDes link for high-loss channels in 40nm technology

Harm Cronie, Klaas Lammert Hofstra, Kia Salimi, Mohammad Amin Shokrollahi, Anant Pratap Singh, Christoph Walter

The continuing demand for higher bandwidth in serial interconnects has pushed the symbol rate of differential lanes into the high-insertion-loss region of channels. Multi-level signaling such as differential PAM-4 [1] has been used to mitigate the loss of electrical channels by lowering the signal spectrum. Such an approach suffers from lower SNR tolerance as well as higher susceptibility to crosstalk and ISI as compared to differential signaling (DS). Coded differential approaches have been reported [2] to mitigate ISI. Our approach is a generalization of DS in which ternary values are transmitted on an 8-wire bus. The set of transmitted values belongs to a code consisting of 256 code-words called the 8b8w-code (8-bits-on-8-wires) [3]. The specific correlations in the code-words of the 8b8w-code eliminate transmit common-mode and simultaneous switching output (SSO) noise and allow for detection via self-referencing comparators (unlike PAM-4), which provides additional noise immunity. Compared to DS, the 8b8w-code offers twice the throughput at 50% of the line power. Compared to PAM-4, the code offers better SNR (3dB) at 38% of the line power with enhanced tolerance of ISI and lower crosstalk generation. The design and experimental verification of an 8b8w transceiver in 40nm CMOS is described. Transmission is achieved up to 12Gb/s per wire over 55cm of Rogers with up to 15dB loss.

2014

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