| 191. |
- Karout, Johnny, 1985, et al.
(författare)
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Achievable rates of multidimensional multisphere distributions
- 2017
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; Part F40-OFC 2017
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Konferensbidrag (refereegranskat)abstract
- The mutual information (MI) of multidimensional multisphere distributions in arbitrary dimensions in the presence of additive white Gaussian noise is derived. We show for instance that 2-D distributions have higher MI than 4-D ones in a range of signal-to-noise ratios.
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| 192. |
- Karout, Johnny, 1985, et al.
(författare)
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CMA Misconvergence in Coherent Optical Communication for Signals Generated from a Single PRBS
- 2011
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Ingår i: Wireless & optical communications conference, New Jersey, 15-16 April 2011. - 9781457704543
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Konferensbidrag (refereegranskat)abstract
- In the experimental study of modulators for coherent optical communications, it is common to generate multilevel signals using a single pseudo-random binary sequence. This simple experimental realization leads to symbol correlation. When modulators are studied in combination with adaptive receiver algorithms that rely on independent data, misconvergence may result. In this contribution, we investigate the impact of such correlation on a standard blind equalization method and provide guidelines to avoid misconvergence. Our results indicate that care needs to be taken when using a single PRBS sequence and that decorrelation delays must be chosen appropriately. We present simulation and theoretical results for 16-QAM, and show how our results can be applied to other multi-level constellations.
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| 193. |
- Karout, Johnny, 1985, et al.
(författare)
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Continuous-Amplitude Modulation for Optical Wireless Channels
- 2012
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Ingår i: Proc. IEEE Photonics Society Summer Topical Meetings, PSST 2012, Seattle, WA: 9 through11 July 2012. - 9781457715266 ; :Article number 6280801, s. 167-168
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Konferensbidrag (refereegranskat)abstract
- Continuous-amplitude modulation for wireless optical channels is presented. For bandwidth measured as 99% in-band power, its spectral efficiency is 4.57 times that of the same modulation format with discontinuous amplitude for the same power requirement.
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| 194. |
- Karout, Johnny, 1985, et al.
(författare)
-
Designing Power-Efficient Modulation Formats for Noncoherent Optical Systems
- 2011
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Ingår i: GLOBECOM - IEEE Global Telecommunications Conference. - 9781424492688
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Konferensbidrag (refereegranskat)abstract
- We optimize modulation formats for the additive white Gaussian noise channel with a nonnegative input constraint, also known as the intensity-modulated direct detection channel, with and without confining them to a lattice structure. Our optimization criteria are the average electrical and optical power. The nonnegativity input signal constraint is translated into a conical constraint in signal space, and modulation formats are designed by sphere packing inside this cone. Some remarkably dense packings are found, which yield more power-efficient modulation formats than previously known. For example, at a spectral efficiency of 1 bit/s/Hz, the obtained modulation format offers a 0.86 dB average electrical power gain and 0.43 dB average optical power gain over the previously best known modulation formats to achieve a symbol error rate of 10^-6. This modulation turns out to have a lattice-based structure. At a spectral efficiency of 3/2 bits/s/Hz and to achieve a symbol error rate of 10^-6, the modulation format obtained for optimizing the average electrical power offers a 0.58 dB average electrical power gain over the best lattice-based modulation and 2.55 dB gain over the best previously known format. However, the modulation format optimized for average optical power offers a 0.46 dB average optical power gain over the best lattice-based modulation and 1.35 dB gain over the best previously known format.
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| 195. |
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| 196. |
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| 197. |
- Karout, Johnny, 1985, et al.
(författare)
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Modulation scheme
- 2010
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Annan publikation (övrigt vetenskapligt/konstnärligt)
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| 198. |
- Karout, Johnny, 1985, et al.
(författare)
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Optimizing Constellations for Single-Subcarrier Intensity-Modulated Optical Systems
- 2012
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 58:7, s. 4645-4659
-
Tidskriftsartikel (refereegranskat)abstract
- We optimize modulation formats for the additive white Gaussian noise channel with nonnegative input, also known as the intensity-modulated direct-detection channel, with and without confining them to a lattice structure. Our optimization criteria are the average electrical, average optical, and peak power. The nonnegative constraint on the input to the channel is translated into a conical constraint in signal space, and modulation formats are designed by sphere packing inside this cone. Some dense packings are found, which yield more power-efficient modulation formats than previously known. For example, at a spectral efficiency of 1.5 bit/s/Hz, the modulation format optimized for average electrical power has a 2.55 dB average electrical power gain over the best known format to achieve a symbol error rate of 10-6 . The corresponding gains for formats optimized for average and peak optical power are 1.35 and 1.72 dB, respectively. Using modulation formats optimized for peak power in average-power limited systems results in a smaller power penalty than when using formats optimized for average power in peak-power limited systems. We also evaluate the modulation formats in terms of their mutual information to predict their performance in the presence of capacity-achieving error-correcting codes, and finally show numerically and analytically that the optimal modulation formats for reliable transmission in the wideband regime have only one nonzero point.
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| 199. |
- Karout, Johnny, 1985, et al.
(författare)
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Power efficient subcarrier modulation for intensity modulated channels
- 2010
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 18:17, s. 17913-17921
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Tidskriftsartikel (refereegranskat)abstract
- We compare formats for optical intensity modulation limited by thermal noise with the assumption of having ideal devices. At the same bitrate and bandwidth, a hitherto unknown format turns out to be more power efficient than known formats. This new modulation, which is a hybrid between on-off keying and phase-shift keying, belongs to the subcarrier modulation family. At asymptotically high signal-to-noise ratios, this hybrid scheme has a 1.2 dB average electrical power gain and 0.6 dB average optical power gain compared to OOK, while it has a 3.0 dB average electrical power gain and 2.1 dB average optical power gain compared to subcarrier QPSK.
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| 200. |
- Keykhosravi, Kamran, 1990, et al.
(författare)
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A Novel Demodulation Scheme for a Memoryless Optical Interference Channel
- 2017
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. ; , s. 66-70
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Konferensbidrag (refereegranskat)abstract
- Matched filtering and sampling, which is known to be the optimal receiver for the linear additive white Gaussian noise channel, is in general suboptimal for a nonlinear medium. Nonetheless, it is commonly used in fiber-optical communication systems with nonlinear distortion. In this paper, a novel demodulation scheme is proposed for a two-user memoryless interference channel, with a type of nonlinear crosstalk that occurs in wavelength-multiplexed optical transmission. We show by simulations that by using this demodulation scheme, unlike matched filtering and sampling, the symbol error rate decreases to zero in the high-power regime.
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