| 1. |
- Bhar, Chayan, 1988, et al.
(författare)
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Channel allocation in elastic optical networks using traveling salesman problem algorithms
- 2019
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 11:10, s. C58-C66
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Tidskriftsartikel (refereegranskat)abstract
- Elastic optical networks have been proposed to support high data rates in metro and core networks. However, frequency allocation of the channels (i.e., channel ordering) in such networks is a challenging problem. This requires arranging the optical channels within the frequency grid with the objective of ensuring a minimum signal-to-noise ratio (SNR). An optimal arrangement results in the highest SNR margin for the entire network. However, determining the optimal arrangement requires an exhaustive search through all possible arrangements (permutations) of the channels. The search space increases exponentially with the number of channels. This discourages an algorithm employing an exhaustive search for the optimal frequency allocation. We utilize the Gaussian noise (GN) model to formulate the frequency allocation (channel ordering) problem as a variant of the traveling salesman problem (TSP) using graph theory. Thereafter, we utilize graph-theoretic tools for the TSP from the existing literature to solve the channel ordering problem. Performance figures obtained for the proposed scheme show that it is marginally inferior to the optimal search (through all possible permutations) and outperforms any random allocation scheme. Moreover, the proposed scheme is implementable for a scenario with a large number of channels. In comparison, an exhaustive search with the GN model and split-step Fourier method simulations are shown to be feasible for a small number of channels only. It is also illustrated that the SNR decreases with an increase in bandwidth when the frequency separation is high.
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| 2. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Biorthogonal modulation in 8 dimensions experimentally implemented as 2PPM-PS-QPSK
- 2014
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Ingår i: Optical Fiber Communication Conference, OFC 2014. - Washington, D.C. : OSA. - 9781557529930 ; , s. Art. no. 6886984-
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate biorthogonal modulation in 8 dimensions as binary pulse-position modulation polarization-switched QPSK. We compare this format with PM-QPSK at the same bit rate and show a 1.4 dB sensitivity gain and 84 % increased transmission distance.
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| 3. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Experimental comparison of PS-QPSK and LDPC-coded PM-QPSK with equal spectral efficiency in WDM transmission
- 2014
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Ingår i: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964035-
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Konferensbidrag (refereegranskat)abstract
- We compare QPSK with a rate 0.75 LDPC-code and PS-QPSK, which have the same spectral efficiency, in long-haul WDM transmission. We show that LDPC-coded PM-QPSK can achieve up to 98% increased transmission distance over uncoded PS-QPSK at BER = 10-3.
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| 4. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Experimental Investigation of a Four-Dimensional 256-ary Lattice-based Modulation Format
- 2015
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Ingår i: 2015 Optical Fiber Communications Conference and Exhibition, OFC 2015, Los Angeles, United States, 22-26 March 2015. - 9781557529374
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Konferensbidrag (refereegranskat)abstract
- A four-dimensional modulation format with 256 point from the D4-lattice (256-D4) is compared to PM-16QAM in experiments. 256-D4 is more sensitive at high OSNR but with a 21.3% overhead turbo product code, PM-16QAM outperforms 256-D4.
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| 5. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Four-Dimensional Estimates of Mutual Information in Coherent Optical Communication Experiments
- 2015
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Ingår i: European Conference on Optical Communications (ECOC), Valencia, Spain, 27 September - 1 October 2015. - 9788460817413
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Konferensbidrag (refereegranskat)abstract
- Mutual information is experimentally investigated for long-haul coherent transmission. Receivers that consider memoryless four-dimensional noise distributions can achieve significantly higher rates than receivers assuming two-dimensional symmetric distributions.
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| 6. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Frequency and polarization switched QPSK
- 2013
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Ingår i: 39th European Conference and Exhibition on Optical Communication, ECOC 2013; London; United Kingdom; 22 September 2013 through 26 September 2013. - : Institution of Engineering and Technology. - 9781849197595 ; :622 CP, s. 816-818
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Konferensbidrag (refereegranskat)abstract
- We propose 8-dimensional biorthogonal modulation as a format with 3 dB increased asymptotic power efficiency over PM-QPSK. We demonstrate one possible experimental implementation of this format based on frequency and polarization switching and compare with dual-carrier PM-QPSK and PS-QPSK.
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| 7. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Impact of 4D Channel Distribution on the Achievable Rates in Coherent Optical Communication Experiments
- 2016
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 34:9, s. 2256-2266
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally investigate mutual information and generalized mutual information for coherent optical transmission systems. The impact of the assumed channel distribution on the achievable rate is investigated for distributions in up to four dimensions. Single channel and wavelength division multiplexing (WDM) transmission over transmission links with and without inline dispersion compensation are studied. We show that for conventional WDM systems without inline dispersion compensation, a circularly symmetric complex Gaussian distribution is a good approximation of the channel. For other channels, such as with inline dispersion compensation, this is no longer true and gains in the achievable information rate are obtained by considering more sophisticated four-dimensional (4D) distributions. We also show that for nonlinear channels, gains in the achievable information rate can also be achieved by estimating the mean values of the received constellation in four dimensions. The highest gain for such channels is seen for a 4D correlated Gaussian distribution.
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| 8. |
- Eriksson, Tobias, 1986, et al.
(författare)
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K-Over-L Multidimensional Position Modulation
- 2014
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 32:12, s. 2254-2262
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Tidskriftsartikel (refereegranskat)abstract
- We analyze a family of modulation formats based on multidimensional position modulation (MDPM) with multiple pulses per frame (K-over-L-MDPM) in combination with quadrature phase shift keying (QPSK), polarization multiplexed QPSK (PM-QPSK) and polarization-switched QPSK (PS-QPSK) for coherent communication systems. MDPM is a generalization of pulse position modulation where different pulse slots can be realized by time slots, polarization states, frequencies, modes of multimode fibers, cores in multicore fibers or a combination of these. We show that by using K-over-L-MDPM with QPSK, it is possible to simultaneously increase both the spectral efficiency and the asymptotic power efficiency over QPSK. We also identify K-ary inverse-MDPM (KiMDPM-QPSK) as the special case of K-over(K -1)-MDPM and show that 4iMDPM-QPSK has a 1.25 dB increased asymptotic power efficiency over QPSK with a maintained spectral efficiency.
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| 9. |
- Eriksson, Tobias, 1986, et al.
(författare)
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Single parity check-coded 16QAM over spatial superchannels in multicore fiber transmission
- 2015
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Ingår i: Optics Express. - : The Optical Society. - 1094-4087 .- 1094-4087. ; 23:11, s. 14569-14582
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally investigate single-parity check (SPC) coded spatial superchannels based on polarization-multiplexed 16-ary quadrature amplitude modulation (PM-16QAM) for multicore fiber transmission systems, using a 7-core fiber. We investigate SPC over 1, 2, 4, 5 or 7 cores in a back-to-back configuration and compare the sensitivity to uncoded PM-16QAM, showing that at symbol rates of 20 Gbaud and at a bit-error-rate (BER) of 10(-3), the SPC superchannels exhibit sensitivity improvements of 2.7 dB, 2.0 dB, 1.7 dB, 1.3 dB, and 1.1 dB, respectively. We perform both single channel and wavelength division multiplexed (WDM) transmission experiments with 22 GHz channel spacing and 20 Gbaud channel symbol rate for SPC over 1, 3 and 7 cores and compare the results to PM-16QAM with the same spacing and symbol rate. We show that in WDM signals, SPC over hl1 core can achieve more than double the transmission distance compared to PM-16QAM at the cost of 0.91 bit/s/Hz/core in spectral efficiency (SE). When sharing the parity-bit over 7 cores, the loss in SE becomes only 0.13 bit/s/Hz/core while the increase in transmission reach over PM-16QAM is 44 %. (C) 2015 Optical Society of America
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| 10. |
- He, Zonglong, 1994, et al.
(författare)
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12.2 bit/s/Hz C-band Transmission with High-Gain Low-Complexity 24-Dimensional Geometric Shaping
- 2024
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Multidimensional (MD) modulation formats enable a larger minimum Euclidean distance than conventional two-dimensional formats. As a structured geometric shaping method, MD Voronoi constellations (VCs) avoid the use of look-up tables and can be implemented with low-complexity encoding and decoding algorithms, outperforming quadrature amplitude modulation (QAM) formats in terms of mutual information. However, it is challenging to maintain the shaping gain in a practical system requiring bit-mapping and forward error correction (FEC) coding. By using a hybrid labeling and multilevel coding scheme integrated with soft-decision FEC coding, MD VCs can achieve high shaping gain compared to QAM formats after soft-decision (SD) decoding. In practical systems, transceiver impairments significantly degrade the system performance, especially for high-cardinality constellations. To investigate of performance of high spectral-efficiency (SE) MD VCs, we employ a 24-dimensional (24D) VC with uncoded SE of 8 bit/symbol/dimension-pair to a spectral superchannel spanning the full C-band. Specifically, the 24D VC with a record constellation size of 7.9×10 28 is applied to dual-polarization coherent transmission over six time slots. The superchannel is composed of 5.0 Gbaud channels spaced at 5.2 GHz, resulting in an overall spectral efficiency of 12.2 bit/s/Hz and a net throughput of 54.2 Tb/s over the entire C-band after 40 km single-mode fiber. It is the first experimental demonstration of a high-SE MD format providing a significant shaping gain after SD decoding.
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