Joint Probabilistic-Nyquist Pulse Shaping for an LDPC-Coded 8-PAM Signal in DWDM Data Center Communications

Abstract

M-ary pulse-amplitude modulation (PAM) meets the requirements of data center communication because of its simplicity, but coarse entropy granularity cannot meet the dynamic bandwidth demands, and there is a large capacity gap between uniform formats and the Shannon limit. The dense wavelength division multiplexing (DWDM) system is widely used to increase the channel capacity, but low spectral efficiency of the intensity modulation/direct detection (IM/DD) solution restricts the throughput of the modern DWDM data center networks. Probabilistic shaping distribution is a good candidate to offer us a fine entropy granularity and efficiently reduce the gap to the Shannon limit, and Nyquist pulse shaping is widely used to increase the spectral efficiency. We aim toward the joint usage of probabilistic shaping and Nyquist pulse shaping with low-density parity-check (LDPC) coding to improve the bit error rate (BER) performance of 8-PAM signal transmission. We optimized the code rate of the LDPC code and compared different Nyquist pulse shaping parameters using simulations and experiments. We achieved a 0.43 dB gain using Nyquist pulse shaping, and a 1.1 dB gain using probabilistic shaping, while the joint use of probabilistic shaping and Nyquist pulse shaping achieved a 1.27 dB gain, which offers an excellent improvement without upgrading the transceivers.

Multiparameter performance monitoring of pulse amplitude modulation channels using convolutional neural networks

“…21,22 First of all, in order to use an adaptive MF according to the transmission conditions, a suitable MF identification is needed. 23 The Nyquist shaping with different roll-off factors (ROFs) is usually applied to alleviate the bandwidth requirement of electrical and optical components, 24,25 while probabilistic shaping (PS) distribution schemes [26][27][28] and forward error correction (FEC) coding with different FEC overheads (OHs) are used for enhancing the tolerance to the OSNR. [29][30][31] Low OSNR always limits the performance of optical links, and channel impairments, such as chromatic dispersion (CD), could severely distort the signal.…”

Two-Dimensional Transmission of Four-Dimensional LDPC-Coded Modulation with Slepian Sequences for DSP-Free 40 km Metro Network Applications

“…The 4D modulation formats applications are investigated mainly for long-haul transmission [13], but have also been demonstrated to have advantages for metro networks applications in our previous work [10]. DWDM is an efficient way to increase overall capacity by allocating a huge amount of data to different wavelength channels and transmit them simultaneously [14][15][16][17][18][19]. The application of pulse shaping scheme, together with the DWDM system, can offer us better spectral efficiency [19].…”

“…DWDM is an efficient way to increase overall capacity by allocating a huge amount of data to different wavelength channels and transmit them simultaneously [14][15][16][17][18][19]. The application of pulse shaping scheme, together with the DWDM system, can offer us better spectral efficiency [19]. FEC coding is an efficient method to increase the channel performance.…”

Special Issue on Optical Communications and Networking: Prospects in Industrial Applications

“…Joint Probabilistic-Nyquist Pulse Shaping for an LDPC-Coded 8-PAM Signal in DWDM Data Center Communications [7] M-ary pulse-amplitude modulation (PAM) has useful applications in data center communication due to its simplicity and low cost. The challenge in PAM systems include providing dynamic bandwidth and reaching the Shannon capacity limit.…”