| 1. |
- 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.
|
|
| 2. |
- 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.
|
|
| 3. |
- 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.
|
|
| 4. |
- 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.
|
|
| 5. |
- Ahmad, Tauseef, 1986, et al.
(författare)
-
Methodology for Power-Aware Coherent Receiver Design
- 2013
-
Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; , s. SPT4D.4-
-
Konferensbidrag (refereegranskat)abstract
- We describe a methodology to design and evaluate DSP hardware for a coherent receiver. Important parameters that can be assessed include DSP power consumption and chip area.
|
|
| 6. |
- Alic, N., et al.
(författare)
-
Joint Statistics and MLSD in Filtered Incoherent High-Speed Fiber-Optic Communications
- 2010
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:10, s. 1564-1572
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, signal statistics and their utilization for detection in narrowly filtered equalized high-speed fiber-optic communications are investigated experimentally. Tradeoffs between log-likelihood metric applications and oversampling are covered in detail. It is, for the first time, demonstrated that performance loss in bandwidth-limited systems can be nearly fully recovered (to within 0.5 dB) by taking advantage of band-width-limitation-induced noise correlations and oversampling.
|
|
| 7. |
- Beygi, Lotfollah, 1977, et al.
(författare)
-
A Discrete-Time Model for Uncompensated Single-Channel Fiber-Optical Links
- 2012
-
Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 60:11, s. 3440-3450
-
Tidskriftsartikel (refereegranskat)abstract
- An analytical discrete-time model is introduced for single-wavelength polarization multiplexed nonlinear fiber-optical channels based on the symmetrized split-step Fourier method (SSFM). According to this model, for high enough symbol rates, a fiber-optic link can be described as a linear dispersive channel with additive white Gaussian noise (AWGN) and a complex scaling. The variance of this AWGN noise and the attenuation are computed analytically as a function of input power and channel parameters. The results illustrate a cubic growth of the noise variance with input power. Moreover, the cross effect between the two polarizations and the interaction of amplifier noise and the transmitted signal due to the nonlinear Kerr effect are described. In particular, it is found that the channel noise variance in one polarization is affected twice as much by the transmitted power in that polarization than by the transmitted power in the orthogonal polarization.The effect of pulse shaping is also investigated through numerical simulations. Finally, it is shown that the analytical performance results based on the new model are in close agreement with numerical results obtained using the SSFM for a symbol rate of 28 Gbaud and above.
|
|
| 8. |
- Beygi, Lotfollah, 1977, et al.
(författare)
-
A novel multilevel coded modulation scheme for fiber optical channel with nonlinear phase noise
- 2010
-
Ingår i: Proc. Global Communications Conference, Miami, FL. - 9781424456383
-
Konferensbidrag (refereegranskat)abstract
- A multilevel coded modulation (MLCM) system in the presence of nonlinear phase noise for fiber optical communication is introduced. The proposed scheme exploits a 16-point ring constellation with nonlinear post compensation of the self phase modulation produced via the Kerr effect. A new set partitioning based on the Ungerboeck approach is introduced to maintain unequal error protection in amplitude and phase direction. The rate allocation for the MLCM component codes for different fiber lengths and transmit powers are done numerically. Simulation results show that the proposed MLCM system provides up to 2 dB gain over a forward error correcting scheme for a block error rates around 10-9, with the same overhead (7%) and complexity. ©2010 IEEE.
|
|
| 9. |
- Beygi, Lotfollah, 1977, et al.
(författare)
-
A novel rate allocation method for multilevel coded modulation
- 2010
-
Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781424469604 ; , s. 1983-1987
-
Konferensbidrag (refereegranskat)abstract
- We present a new rate allocation scheme for multilevelcoded modulation based on the minimization of the totalblock error rate (BLER). The proposed method uses affine codecomponents and hard decision multistage decoding. Exhaustivesearch for the rate allocation which minimizes the total BLERjustifies the near-optimum performance of the introduced methodin moderate to high SNRs. Compared to previous approaches thisnew rate allocation scheme can improve the performance of thesystem by 1 dB at BLER = 10−6 for 16-QAM with Ungerboeck setpartitioning. Interestingly, our results indicate that the optimumrate allocation is a function of the SNR. Finally, the performanceof some specific codes are evaluated by simulation and unionbounds to verify the theoretical results.
|
|
| 10. |
- Beygi, Lotfollah, 1977, et al.
(författare)
-
Adaptive Coded Modulation for Nonlinear Fiber-Optical Channels
- 2012
-
Ingår i: 2012 IEEE Globecom Workshops, Anaheim, USA, 3-7 December 2012. - 9781467349420 ; , s. 331-335
-
Konferensbidrag (refereegranskat)abstract
- A low complexity hybrid polar low-density parity check (LDPC) coded modulation (CM) scheme is introduced for a single-wavelength fiber-optical channel. In the proposed scheme, we exploit a low complexity probabilistic shaping together with a four-dimensional (4D) mapping to reduce the complexity of a 4D non-binary LDPC CM scheme for fiber-optic channels. The proposed scheme has a flexible structure and it can be used as an adaptive-rate CM scheme. The numerical results show that the forward error correction (FEC) threshold of the introduced CM scheme can be significantly improved by probabilistic shaping with a negligible increase in the system complexity. In particular, the FEC threshold for the uncoded symbol error rate of the introduced CM scheme with 4D 16-ary quadrature amplitude modulation can be improved from 0.058 to 0.072 by exploiting a shaping overhead (redundancy) of 0.016 for an information bit error rate of 10^{-5}.
|
|
