Overview of high-speed TDM-PON beyond 50  Gbps per wavelength using digital signal processing [Invited Tutorial]

Abstract

The recent evolution of passive optical network standards and related research activities for physical layer solutions that achieve bit rates well above 10 Gbps per wavelength ( λ ) is discussed. We show that the advancement toward 50, 100, and 200 G b p s / λ will certainly require a strong introduction of advanced digital signal processing (DSP) technologies for linear, and maybe nonlinear, equalization and for forward error correction. We start by reviewing in detail the current standardization activities in the International Telecommunication Union and the Institute of Electrical and Electronics Engineers, and then we present a comparison of the DSP approaches for traditional direct detection solutions and for future coherent detection approaches.

Performance comparison of 100Gbps upstream coherent passive optical network

“…The standardization of 25G-Ethernet PON (EPON) was completed in June 2020 by the IEEE 802.3ca Task Force based on 25 Gbps wavelengths in a multi-lane configuration. For the future PON systems, more than 50 Gb/s/λ of PON are being reported [6][7][8][9][10]. A 50 Gbps EPON system with a 25 Gbps multilane configuration achieves a loss budget of 29 dB, which is the same as 10G-EPON.…”

Experimental Demonstration of In-Field 400G Coherent Metro-Access Convergence

“…For techno-economic reasons, PON transmission is based on intensity modulation and direct detection (IM-DD), like all the other shorter reach fiber applications. The PON IM-DD-based IEEE and ITU-T standards are anyway approaching today fundamental physical layer limitations in terms of increasing transmission speed (see the recent 50G-PON ITU-T standard [1]), but also in reach and/or optical power budget [2]. These shortcomings are today being addressed in an ITU-T discussion on future 100 or 200 Gbps/λ PON by considering new solutions, such as 4-PAM as opposed to traditional binary OOK, even more powerful FEC and strong of pre-or post-equalization through DSP [2,3].…”

“…The PON IM-DD-based IEEE and ITU-T standards are anyway approaching today fundamental physical layer limitations in terms of increasing transmission speed (see the recent 50G-PON ITU-T standard [1]), but also in reach and/or optical power budget [2]. These shortcomings are today being addressed in an ITU-T discussion on future 100 or 200 Gbps/λ PON by considering new solutions, such as 4-PAM as opposed to traditional binary OOK, even more powerful FEC and strong of pre-or post-equalization through DSP [2,3]. While this brainstorming is not closed yet, it seems that for 100G-PON, IM-DD will again be used.…”

Simplified coherent receivers for passive optical networks

“…Studying trends from previous standards by both IEEE and ITU-T, it is likely that a four-fold increase in capacity will be the target, as smaller increases may not entice industry members to invest in the technology. As such 200 Gb/s PON is a focus in the research community [5] .…”

“…There are multiple approaches, that are proposed to achieve 200 Gb/s. It is clear, that the traditional approach of intensity modulation / direct detection (IM/DD) coupled with non-return-tozero signalling is unlikely to meet the power budget requirements [5], [6] . Demonstration of IM/DD PON for 200 Gb/s line rate exist, however use PAM-4 or higher modulation [7], [8] format to increase spectral efficiency and are only able to meet power budget requirements using extensive DSP [9] and using Raman amplifiers [10] .…”