Showing papers by "Norbert Hanik published in 2015"
22 Mar 2015
TL;DR: In this paper, an LDPC coded modulation scheme with probabilistic shaping, optimized interleavers and noniterative demapping is proposed, which increases the transmission distance by 8% compared to uniformly distributed input.
Abstract: An LDPC coded modulation scheme with probabilistic shaping, optimized interleavers and noniterative demapping is proposed. Full-field simulations show an increase in transmission distance by 8% compared to uniformly distributed input.
81 citations
TL;DR: In this paper, lower bounds on mutual information (MI) of long-haul optical fiber systems for hard-decision and softdecision decoding are studied. And the advantages of using MI over the prevailing Q-factor as a figure of merit of coded optical systems are also highlighted.
Abstract: Lower bounds on mutual information (MI) of long-haul optical fiber systems for hard-decision and soft-decision decoding are studied. Ready-to-use expressions to calculate the MI are presented. Extensive numerical simulations are used to quantify how changes in the optical transmitter, receiver, and channel affect the achievable transmission rates of the system. Special emphasis is put to the use of different quadrature amplitude modulation formats, channel spacings, digital back-propagation schemes and probabilistic shaping. The advantages of using MI over the prevailing Q-factor as a figure of merit of coded optical systems are also highlighted.
80 citations
TL;DR: In this paper, an LDPC coded modulation scheme with probabilistic shaping, optimized interleavers and noniterative demapping is proposed, which increases the transmission distance by 8% compared to uniformly distributed input.
Abstract: An LDPC coded modulation scheme with probabilistic shaping, optimized interleavers and noniterative demapping is proposed. Full-field simulations show an increase in transmission distance by 8% compared to uniformly distributed input.
70 citations
TL;DR: In this article, a phase noise tracking algorithm based on the Tikhonov distribution was proposed for the IDRA WDM channel, which is suitable for the non-linear phase noise due to cross-phase modulation from neighboring channels.
Abstract: In this paper, the wavelength division multiplexed (WDM) fiber optic channel is considered. It is shown that for ideal distributed Raman amplification (IDRA), the Wiener process model is suitable for the non-linear phase noise due to cross phase modulation from neighboring channels. Based on this model, a phase noise tracking algorithm is presented. We approximate the distribution of the phase noise at each time instant by a mixture of Tikhonov distributions, and derive a closed form expression for the posterior probabilities of the input symbols. This reduces the complexity dramatically compared to previous trellis-based approaches, which require numerical integration. Further, the proposed method performs very well in low-to-moderate signal-to-noise ratio (SNR), where standard decision directed (DD) methods, especially for high-order modulation, fail. The proposed algorithm does not rely on averaging, and therefore does not experience high error floors at high SNR in severe phase noise scenarios. The laser linewidth (LLW) tolerance is thereby increased for the entire SNR region compared to previous DD methods. In IDRA WDM links, the algorithm is shown to effectively combat the combined effect of both laser phase noise and non-linear phase noise, which cannot be neglected in such scenarios. In a more practical lumped amplification scheme, we show near-optimal performance for 16 QAM, 64 QAM, and 256 QAM with LLW up to 100 kHz, and reasonable performance for LLW of 1 MHz for 16 QAM and 64 QAM, at the moderate received SNR region. The performance in these cases is close to the information rate achieved by the above mentioned trellis processing.
50 citations
22 Mar 2015
TL;DR: A digital algorithm for joint pre-compensation of the low-pass frequency response and I/Q skew in transmitters is presented and results for DP-16QAM to DP-256QAM at 37.41 GBaud are presented.
Abstract: We present a digital algorithm for joint pre-compensation of the low-pass frequency response and I/Q skew in transmitters. Experimental results for DP-16QAM to DP-256QAM at 37.41 GBaud are presented.
40 citations
TL;DR: In this article, a photonic lantern based 3-D-waveguide spatial multiplexer with capacity of 41.6 Tbit/s (net data rate 16.8 T bit/s) over 12 spatial and polarization modes is demonstrated.
Abstract: Signal transmission with capacity of 41.6 Tbit/s (net data rate 16.8 Tbit/s) over 12 spatial and polarization modes is demonstrated. Dense optical orthogonal frequency division multiplexing signals with a channel spacing of 16.7 GHz across the full C band is generated. The resulting 12 tributaries are (de-)multiplexed using a novel fully packaged photonic lantern based 3-D-waveguide spatial-multiplexer. The spatially multiplexed signals are transmitted over 74.17-km weakly coupled six-mode few mode fiber enabling inline differential mode delay compensation. All 12 tributaries are detected using three oscilloscopes via coherent heterodyne receiver. The bit error rate of the 255 channel in each mode is evaluated to be below the forward error correction limit 2.4 $\,\times\,$ 10 ${\bf ^{-2}}$ assuming 20% overhead.
29 citations
Journal Article•
TL;DR: In this article, a photonic lantern based 3-D-waveguide spatial multiplexer with capacity of 41.6 Tbit/s (net data rate 16.8 T bit/s) over 12 spatial and polarization modes is demonstrated.
Abstract: Signal transmission with capacity of 41.6 Tbit/s (net data rate 16.8 Tbit/s) over 12 spatial and polarization modes is demonstrated. Dense optical orthogonal frequency division multiplexing signals with a channel spacing of 16.7 GHz across the full C band is generated. The resulting 12 tributaries are (de-)multiplexed using a novel fully packaged photonic lantern based 3-D-waveguide spatial-multiplexer. The spatially multiplexed signals are transmitted over 74.17-km weakly coupled six-mode few mode fiber enabling inline differential mode delay compensation. All 12 tributaries are detected using three oscilloscopes via coherent heterodyne receiver. The bit error rate of the 255 channel in each mode is evaluated to be below the forward error correction limit 2.4 × 10-2 assuming 20% overhead.
28 citations
TL;DR: In this article, an OFDMA-based PON with a transmission employing intensity modulation/direct detection in downstream and a remodulation of a remotely seeded carrier provided by the optical line terminal with coherent detection in the upstream is proposed.
Abstract: The orthogonal frequency division multiple access (OFDMA)-based passive optical network (PON) is a potential candidate to meet the flexibility requirements for next-generation optical access networks. We propose an OFDMA-based PON with a transmission employing intensity modulation/direct detection in the downstream and a remodulation of a remotely seeded carrier provided by the optical line terminal with coherent detection in the upstream, which enables cost-effective colorless optical network units (ONUs). Furthermore, an OFDMA-PON field trial using the proposed scheme over 37.5 km feeder fiber is demonstrated. A power budget supporting 32 ONUs with dynamic bandwidth allocation and trellis coded modulation (TCM) is reported.
19 citations
03 Dec 2015
TL;DR: In this article, a blind trellis-based receiver is proposed to exploit temporal correlations in the phase, achievable rates are studied and a blind Trellis based receiver is presented, where gains of 0.5 bit per symbol are found in point-to-point links irrespective of the symbol rate.
Abstract: Exploiting temporal correlations in the phase, achievable rates are studied and a blind trellis-based receiver is presented. Gains of 0.5 bit per symbol are found in point-to-point links irrespective of the symbol rate. These gains disappear in network configurations.
18 citations
12 Nov 2015
TL;DR: This paper shows that blind decision-directed CPE with regular block lengths removes a large portion of the memory, making it virtually impossible in practice to quantify correlations that come from propagation effects, or to obtain rate gains by exploiting the nonlinear phase noise (NLPN).
Abstract: Carrier phase estimation (CPE) is an integral part of the digital signal processing (DSP) of coherent optical communication systems as it compensates laser phase noise (LPN) introduced by free-running transmitter and local oscillating (LO) lasers. Nonlinear interactions during propagation are another source of correlated phase noise. In this paper, we show through simulations and in experiments that blind decision-directed (DD) CPE with regular block lengths removes a large portion of the memory. This makes it virtually impossible in practice to quantify correlations that come from propagation effects, or to obtain rate gains by exploiting the nonlinear phase noise (NLPN). Larger CPE block lengths leave the memory partly intact. This, however, comes at the expense of reduced information rates. We are able to fully recover this rate loss in simulations by using idealized processing of phase distortions. In experiments with full DSP, an almost full rate recovery is reported.
15 citations
TL;DR: In this paper, the impact of the assumed channel distribution on the achievable rate was investigated for distributions in up to four dimensions for single channel and wavelength division multiplexing (WDM) transmission over transmission links with and without inline dispersion compensation.
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.
01 Jun 2015
TL;DR: In this article, the authors demonstrate a record 38.4Tb/s 64QAM C-band transmission over 762km of field deployed SSMF fiber, connecting Lyon and Marseille, France, employing hybrid EDFA-Raman amplification and achieve a spectral efficiency of 8 b/s/Hz.
Abstract: We demonstrate a record 38.4Tb/s 64QAM C-band transmission over 762km of field deployed SSMF fiber, connecting Lyon and Marseille, France, employing hybrid EDFA-Raman amplification and achieve a spectral efficiency of 8b/s/Hz. Furthermore, we demonstrate, for the first time to our knowledge, flexi-rate transmission over the same commercial link, using quad-carrier 1Tb/s 16QAM (24.0 Tb/s), 1Tb/s 32QAM (32.0 Tb/s) and 1.2Tb/s 64QAM (38.4 Tb/s).
TL;DR: Lower bounds on mutual information (MI) of long-haul optical fiber systems for hard-dec decision and soft-decision decoding are studied and special emphasis is put to the use of different quadrature amplitude modulation formats, channel spacings, digital back-propagation schemes and probabilistic shaping.
Abstract: Lower bounds on mutual information (MI) of long-haul optical fiber systems for hard-decision and soft-decision decoding are studied. Ready-to-use expressions to calculate the MI are presented. Extensive numerical simulations are used to quantify how changes in the optical transmitter, receiver, and channel affect the achievable transmission rates of the system. Special emphasis is put to the use of different quadrature amplitude modulation formats, channel spacings, digital back-propagation schemes and probabilistic shaping. The advantages of using MI over the prevailing $Q$-factor as a figure of merit of coded optical systems are also highlighted.
03 Dec 2015
TL;DR: Mutual information is experimentally investigated for long-haul coherent transmission and receivers that consider memoryless four-dimensional noise distributions can achieve significantly higher rates than receivers assuming two-dimensional symmetric distributions.
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.
TL;DR: Numerical simulations are used to prove the robustness of probabilistic shaping to a mismatch between the constellation used and the signal-to-noise ratio (SNR) of the channel.
Abstract: Probabilistic shaping of quadrature amplitude modulation (QAM) is used to enhance the sensitivity of an optical communication system. Sensitivity gains of 0.43 dB and 0.8 dB are demonstrated in back-to-back experiments by shaping of 16QAM and 64QAM, respectively. Further, numerical simulations are used to prove the robustness of probabilistic shaping to a mismatch between the constellation used and the signal-to-noise ratio (SNR) of the channel. It is found that, accepting a 0.1 dB SNR penalty, only four shaping distributions are required to support these gains for 64QAM.
Posted Content•
13 Oct 2015
TL;DR: In this article, probabilistic shaping of quadrature amplitude modulation (QAM) is used to enhance the sensitivity of an optical communication system, which is demonstrated in back-to-back experiments by shaping of 16QAM and 64QAM, respectively.
Abstract: Probabilistic shaping of quadrature amplitude modulation (QAM) is used to enhance the sensitivity of an optical communication system. Sensitivity gains of 0.43 dB and 0.8 dB are demonstrated in back-to-back experiments by shaping of 16QAM and 64QAM, respectively. Further, numerical simulations are used to prove the robustness of probabilistic shaping to a mismatch between the constellation used and the signal-to-noise ratio (SNR) of the channel. It is found that, accepting a 0.1 dB SNR penalty, only four shaping distributions are required to support these gains for 64QAM.
01 Jan 2015
TL;DR: Numerical simulations are used to prove the robustness of probabilistic shaping to a mismatch between the constellation used and the signal-to-noise ratio (SNR) of the channel.
Abstract: Probabilistic shaping of quadrature amplitude modulation (QAM) is used to enhance the sensitivity of an optical communication system. Sensitivity gains of 0.43 dB and 0.8 dB are demonstrated in back-to-back experiments by shaping of 16QAM and 64QAM, respectively. Further, numerical simulations are used to prove the robustness of probabilistic shaping to a mismatch between the constellation used and the signal-to-noise ratio (SNR) of the channel. It is found that, accepting a 0.1 dB SNR penalty, only four shaping distributions are required to support these gains for 64QAM.
05 Jul 2015
TL;DR: The gap of a practical FEC scheme to its asymptotic limit is studied and it is found that the gain of complex SD decoding over HD decoding can be very small.
Abstract: We study lower bounds on mutual information that are achievable rates for optimal and sub-optimal hard-decision (HD) and soft-decision (SD) decoding. These rates represent the maximum amount of information we can convey over a memoryless channel with a fixed input if ideal forward error correction (FEC) is employed. We find that the gain of complex SD decoding over HD decoding can be very small, depending on the modulation format and the system parameters. We further study the gap of a practical FEC scheme to its asymptotic limit.