Signal Shaping to Achieve OOK and PSK Co-Existence for Improved Optical Access Network Performance

Abstract

This paper proposes a novel symbol mapping that uses signal shaping to alleviate the BER problem in constellation sharing with the use of phase information. This mapping solves one of the most critical problems; the small Euclid distance of the PSK symbols in the constellation sharing of OOK and PSK in Passive Optical Networks (PONs). Constellation sharing enables next generation PONs to overlay existing PONs with the use of an advanced modulation format based on the Digital Signal Processing (DSP) technology that well supports migration of the access network. The modulation format of Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), and Quadrature Amplitude Modulation (QAM) can co-exist with the existing PONs, which utilize On-off Keying (OOK). The proposed mapping is designed to maximize the symbol distance assuming the co-existence of OOK and PSK. This paper shows the configuration, operation principles, and performance of the proposed signal mapping for OOK and PSK. It also shows that constellation sharing improves the BER characteristics of OOK and PSK in conjunction with an existing PON and the next generation technology.