Impact of the Overall Electrical Filter Shaping in Next-Generation 25G and 50G PON

TL;DR

This paper analyzes how the electrical filter shaping affects high-speed PON transceiver performance, emphasizing the importance of out-of-band response specifications like -20dB bandwidth for optimal modulation format performance.

Contribution

It provides an exhaustive numerical analysis of electrical filter shaping impacts on various modulation formats for next-generation HS-PON transceivers, highlighting the limitations of using only -3dB bandwidth.

Findings

Out-of-band electrical response significantly influences modulation performance.

-20dB bandwidth is a critical parameter for transceiver design.

Normalized graphs aid in designing better HS-PON transceivers.

Abstract

Next-generation high-speed passive optical network (HS-PON) transceivers supporting 25, 50 and 100 Gb/s are under the early stage of their standardization process. One key aspect of this process is the choice of the best modulation format. To this end, performance comparisons among several modulation formats against different physical constraints have been presented in literature and are still being carried out. In our contribution, we performed an exhaustive analysis on the impact of transceivers electrical frequency response shape on the performance of 2-levels pulse amplitude modulation (PAM-2), 4-levels PAM (PAM-4), electrical and optical duobinary modulation formats with adaptive equalizer at the receiver side. We show by means of numerical simulations that the specification of the typically used -3dB bandwidth is not sufficient, since also out-of-band electrical frequency response specifications (such as the -20dB bandwidth) has a huge impact on the performance of the analyzed modulation formats. The normalized graphs given at the end of the paper in terms of -3dB and -20 dB bandwidths can thus be useful for the design of the next generation of HS-PON transceivers.