| 291. |
- Li, Jianqiang, 1983, et al.
(författare)
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Approaching Nyquist Limit in WDM Systems by Low-Complexity Receiver-Side Duobinary Shaping
- 2012
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 30:11, s. 1664 - 1676
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Tidskriftsartikel (refereegranskat)abstract
- A novel low-complexity coherent receiver solution is presented to improve spectral efficiency in wavelength-division multiplexing (WDM) systems. It is based on the receiver-side partial-response equalization and maximum-likelihood sequence detection (MLSD) in pre-filtered WDM systems. The partial- response equalization shapes the channel into an intermediate state with a known partial response which is finally recovered by MLSD without the need of channel estimation. In this scheme, the severe ISI induced by the pre-filtering can be shared between the partial-response equalization and MLSD. Therefore, a tradeoff can be made between complexity and performance. The feasibility of receiver-side partial-response shaping relaxes the efforts and requirements on the transmitter-side pre-filtering, which permits the mature WDM components to implement pre-filtering. In addition, the partial-response equalization or shaping structure is also improved based on our prior art, which further simplifies the overall scheme. For near-baudrate-spacing optically-pre-filtered WDM systems, duobinary response is experimentally proved as a good intermediate response to shape. Due to the short memory of the duobinary response, the complexity of the receiver based on duobinary shaping has been reduced to a low level. As a whole, the proposed scheme provides a good alternative to Nyquist-WDM at comparable spectral efficiencies. With the proposed receiver-side duobinary shaping technique, three sets of experiments have been carried out to verify the improved duobinary shaping scheme and meanwhile demonstrate the main features, including 5*112-Gbit/s polarization-multiplexed quadrature phase-shift keying (PM-QPSK) WDM transmission over a 25-GHz grid, single- channel 40-Gbaud PM-QPSK experiment, and 30-GHz-spaced 3*224-Gbit/s PM 16-ary quadrature amplitude modulation transmission.
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| 292. |
- Li, Jianqiang, 1983, et al.
(författare)
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Building up low-complexity spectrally-efficient Terabit superchannels by receiver-side duobinary shaping
- 2012
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 20:9, s. 10271-10282
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Tidskriftsartikel (refereegranskat)abstract
- Recently, an increasing interest has been put on spectrally-efficient multi-carrier superchannels for beyond 100G. Apart from orthogonal frequency-division multiplexing (OFDM) and Nyquist wavelength-division multiplexing (WDM), another low-complexity WDM approach based on transmitter-side pre-filtering and receiver-side duobinary shaping is proposed to build up multi-carrier superchannels. This approach is referred to as receiver-side duobinary-shaped WDM (RS-DBS-WDM). Generation and transmission of a 1.232-Tbit/s 11-carrier superchannel is experimentally demonstrated. The superchannel signal can be well fit inside the passband of multiple 300-GHz reconfigurable optical add and drop multiplexers (ROADMs). In the superchannel scenario, the proposed RS-DBS-WDM is qualitatively compared with OFDM and Nyquist-WDM in terms of implementation complexity. In sum, the proposed RS-DBS-WDM approach features high transceiver analog-bandwidth efficiency, high spectral-efficiency, the absence of specific spectral manipulation, compatibility with conventional WDM technologies and coherent detection algorithms, and comparable implementation penalty.
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| 293. |
- Li, Jianqiang, 1983, et al.
(författare)
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Exploiting the Faster-Than-Nyquist Concept in Wavelength-Division Multiplexing Systems Using Duobinary Shaping
- 2012
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Ingår i: ZTE Communications. - 1673-5188. ; 10:1, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- This paper begins with Nyquist wavelength-division multiplexing (WDM) and then introduces faster-than-Nyquist. In faster-than-Nyquist, a certain amount of inter-symbol interference (ISI) is accepted, which violates the fundamental principle of Nyquist WDM. This results in much-relaxed transceiver bandwidth and simpler spectral design. However, in faster-than-Nyquist, implementation complexity is shifted from the transmitter side to the receiver side. Therefore, successful application of faster-than-Nyquist depends on innovation in the receiver structure. In this paper, we discuss the guidelines for implementing suboptimum, low-complexity receivers based on faster-than-Nyquist. We suggest that duobinary shaping is a good technique for trading off achievable spectral efficiency, detection performance, and implementation complexity and might be preferable to Nyquist WDM. Experiments are conducted to verify robustness of the proposed technique.
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| 294. |
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| 295. |
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| 296. |
- Li, Jie, 1966, et al.
(författare)
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OTDM Add & Drop Multiplexer Based on XPM-Induced Wavelength Shifting in Highly Nonlinear Fiber
- 2005
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 23:9, s. 2654-2661
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study experimentally and numerically simultaneous time-domain add-drop multiplexing for high-speed optical time-division multiplexing (OTDM) networks based on cross-phase-modulation (XPM)-induced wavelength shifting in a 50-m highly nonlinear fiber. This scheme needs only a single-channel clock rate and does not alter the input signal wavelength. Simultaneous add and drop operations at 80 Gb/s have been demonstrated experimentally with less than 1-dB power penalty for the dropped channel and no distinct bit-error-rate (BER) degradation for the added channel. Numerical simulations show that the experimental results are only limited by the available signal pulsewidth, and simultaneous add-drop multiplexing at 160-Gb/s or higher bit rates is possible with this scheme by employing control and signal pulses with proper pulsewidths. © 2005 IEEE.
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| 297. |
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| 298. |
- Li, Jianqiang, 1983, et al.
(författare)
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Transmission of 1.936 Tb/s (11 x 176 Gb/s) DP-16QAM superchannel signals over 640 km SSMF with EDFA only and 300 GHz WSS channel
- 2012
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 20:26, s. B223-B231
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Tidskriftsartikel (refereegranskat)abstract
- With an improved receiver-side spectral shaping technique by introducing and optimizing one tap coefficient in the intermediate response, we successfully transmitted 1.936 Tb/s (11 x 176 Gb/s) DP-16QAM superchannel signal over 8 x 80 km SSMF with EDFA-only and two 280 GHz wavelength selective switches (WSSs) in support of future 1.6 Tb/s Ethernet with up to 20% forward error correction overhead. The 280 GHz 3-dB bandwidth of the WSS passband permits a sufficient guardband if the 1.936 Tb/s superchannel signals are placed in a 300 GHz WSS channel.
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| 299. |
- Li, Shen, 1994, et al.
(författare)
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Antialiased transmitter-side digital backpropagation
- 2020
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 32:18, s. 1211-1214
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Tidskriftsartikel (refereegranskat)abstract
- Digital backpropagation (DBP) is an electronic scheme for compensating nonlinear distortions in fiber transmission systems. Due to the nonlinearity-induced spectral broadening, the data must be oversampled to avoid aliasing, which increases the complexity and power consumption of the scheme. In this work, we show that aliasing can alternatively be prevented by distributed antialiasing filters, at a lower complexity. We proposed a new modified split-step Fourier method (SSFM) with easy-To-implement low-pass filters (LPFs) in the linear steps to avoid aliasing due to spectral broadening. Both the forward fiber propagation and a transmitter-side DBP are simulated using the modified SSFM. High-order modulation formats such as 256-Ary quadrature-Amplitude-modulation (256-QAM) and 1024-QAM transmissions at 28 Gbaud and 64 Gbaud over 1000 km fiber are considered, and our results show that the complexity of the DBP can be reduced by up to 50%. The optimal bandwidth of the LPFs is studied for both forward propagation and the DBP.
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| 300. |
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