| 31. |
- Agrell, Erik, 1965, et al.
(författare)
-
Capacity of a nonlinear optical channel with finite memory
- 2014
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 32:16, s. 2862-2876
-
Tidskriftsartikel (refereegranskat)abstract
- The channel capacity of a nonlinear, dispersive fiber-optic link is revisited. To this end, the popular Gaussian noise (GN) model is extended with a parameter to account for the finite memory of realistic fiber channels. This finite-memory model is harder to analyze mathematically but, in contrast to previous models, it is valid also for nonstationary or heavy-tailed input signals. For uncoded transmission and standard modulation formats, the new model gives the same results as the regular GN model when the memory of the channel is about ten symbols or more. These results confirm previous results that the GN model is accurate for uncoded transmission. However, when coding is considered, the results obtained using the finite-memory model are very different from those obtained by previous models, even when the channel memory is large. In particular, the peaky behavior of the channel capacity, which has been reported for numerous nonlinear channel models, appears to be an artifact of applying models derived for independent input in a coded (i.e., dependent) scenario. © 1983-2012 IEEE.
|
|
| 32. |
- Agrell, Erik, 1965, et al.
(författare)
-
Influence of Behavioral Models on Multiuser Channel Capacity
- 2015
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 33:17, s. 3507-3515
-
Tidskriftsartikel (refereegranskat)abstract
- In order to characterize the channel capacity of a wavelength channel in a wavelength-division multiplexed (WDM) system, statistical models are needed for the transmitted signals on the other wavelengths. For example, one could assume that the transmitters for all wavelengths are configured independently of each other, that they use the same signal power, or that they use the same modulation format. In this paper, it is shown that these so-called behavioral models have a profound impact on the single-wavelength achievable information rate. This is demonstrated by establishing, for the first time, upper and lower bounds on the maximum achievable rate under various behavioral models, for a rudimentary WDM channel model.
|
|
| 33. |
- Agrell, Erik, 1965, et al.
(författare)
-
Modulation and detection for multicore superchannels with correlated phase noise [Invited]
- 2018
-
Ingår i: 2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings. ; Part F94-CLEO_SI 2018
-
Konferensbidrag (refereegranskat)abstract
- SDM fibers offer new opportunities and challenges for joint transmitter and receiver processing. We review multidimensional modulation and detection theory, describe algorithms for phase tracking and detection over spatial superchannels, and present some experimental results.
|
|
| 34. |
- Agrell, Erik, 1965, et al.
(författare)
-
On the symbol error probability of regular polytopes
- 2011
-
Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 57:6, s. 3411-3415
-
Tidskriftsartikel (refereegranskat)abstract
- An exact expression is derived for the symbol error probability when the vertices of the four-dimensional 24-cell are used for digital transmission in Gaussian noise. Corresponding expressions for other regular convex polytopes are summarized. Numerically stable versions of these error probabilities are also obtained. © 2011 IEEE.
|
|
| 35. |
|
|
| 36. |
- Agrell, Erik, 1965, et al.
(författare)
-
Power-efficient modulation formats in coherent transmission systems
- 2009
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 27:22, s. 5115-5126
-
Tidskriftsartikel (refereegranskat)abstract
- Coherent optical transmission systems have a four-dimensional (4-D) signal space (two quadratures in two polarizations). These four dimensions can be used to create modulation formats that have a better power efficiency (higher sensitivity) than the conventional binary phase shift keying/quadrature phase shift keying (BPSK/QPSK) signals. Several examples are given, with some emphasis on a 24-level format and an 8-level format, including descriptions of how they can be realized and expressions for their symbol and bit error probabilities. These formats are, respectively, an extension and a subset of the commonly used 16-level dual-polarization QPSK format. Sphere packing simulations in 2, 3, and 4 dimensions, up to 32 levels, are used to verify their optimality. The numerical results, as the number of levels increases, are shown to agree with lattice-theoretical results. Finally, we point out that the use of these constellations will lead to improved fundamental sensitivity limits for optical communication systems, and they may also be relevant as a way of reducing power demands and/or nonlinear influence. © 2009, IEEE. All rights reserved.
|
|
| 37. |
- Agrell, Erik, 1965, et al.
(författare)
-
Roadmap of optical communications
- 2016
-
Ingår i: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 18:6
-
Tidskriftsartikel (refereegranskat)abstract
- Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.
|
|
| 38. |
- Agrell, Erik, 1965, et al.
(författare)
-
Satellite constellations: Towards the nonlinear channel capacity
- 2012
-
Ingår i: 25th IEEE Photonics Conference, IPC 2012, Burlingame, 23 - 27 September 2012 [Invited]. - 9781457707315 ; , s. 316-317
-
Konferensbidrag (refereegranskat)abstract
- We present a family of adaptive constellations that, in a nonlinear optical fiber channel model, has a mutual information (modulation-constrained capacity) that does not decrease with signal power.
|
|
| 39. |
- Agrell, Erik, 1965, et al.
(författare)
-
WDM channel capacity and its dependence on multichannel adaptation models
- 2013
-
Ingår i: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC [Invited]. - 9781479904570
-
Konferensbidrag (refereegranskat)abstract
- Optical multichannel systems are often characterized by the channel capacity of a single channel, assuming a certain adaptation behavior of the other channels. We investigate some common adaptation models, which lead to dramatically different capacities.
|
|
| 40. |
- Akhmediev, N., et al.
(författare)
-
Cherenkov radiation emitted by solitons in optical fibers
- 1995
-
Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 51:3, s. 2602-2607
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a simple, fully analytic method of calculating the amount of radiation emitted by optical solitons perturbed by higher-order dispersion effects in fibers and find good agreement with numerical results. It is pointed out that this radiation mechanism is analogous to the well-known Cherenkov radiation processes in nonlinear optics. © 1995 The American Physical Society.
|
|
