Comparison of Short Blocklength Sphere Shaping and Nonlinearity Compensation in WDM Systems

Abstract

In optical communication systems, short blocklength probabilistic enumerative sphere shaping (ESS) provides both linear shaping gain and nonlinear tolerance. In this work, we investigate the performance and complexity of ESS in comparison with fiber nonlinearity compensation via digital back propagation (DBP) with different steps per span. We evaluate the impact of the shaping blocklength in terms of nonlinear tolerance and also consider the case of ESS with a Volterra-based nonlinear equalizer (VNLE), which provides lower complexity than DBP. In single-channel transmission, ESS with VNLE achieves similar performance in terms of finite length bit-metric decoding rate to uniform signaling with one step per span DBP. In the context of a dense wavelength-division multiplexing (WDM) transmission system, we show that ESS outperforms uniform signaling with DBP for different step sizes.

Multi-dimensional Short Blocklength Probabilistic Shaping for Digital Subcarrier Multiplexing Systems

“…Short blocklength shaping has attracted special attention due to its nonlinear tolerance gain with respect to the long blocklength case and uniform signaling [2,4,5], and it is more interesting in case of low rate loss shaping schemes like sphere shaping [2,6]. This makes short blocklength shaping a promising approach to be considered for practical hardware implementation because of the low latency and complexity in comparison with long blocklength shaping and nonlinearity compensation via digital signal processing [7]. The nonlinear tolerance gain has been shown to be dependent on the temporal structure of the shaped signal [8].…”

A tutorial on fiber Kerr nonlinearity effect and its compensation in optical communication systems

“…The deployment of wavelength division multiplexing (WDM) technology, which enables the multiplexing of several optical signals in the same fiber, dramatically increases the fiber capacity [8,9]. A few years ago, an optical superchannel system has been introduced for 400 Gb s −1 or 1 Tb s −1 optical transmission systems [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. This system effectively splits the given WDM channel into smaller subcarriers separated by smaller guard-bands and transmitted as a single entity along the optical network.…”