Evaluation of TCM to Coexisting OOK and PSK in Optical Access

Studies for enhancing network speed and capacity to handle the rapid increases in traffic are being conducted. Even in optical access, which is the backbone network, studies on next generation modulation schemes that utilize phase and amplitude, rather than modulation by conventional light intensity, are being conducted. However, it is difficult to update all the terminals at once, and there is a possibility that signals with old and new modulation schemes coexist on one optical fiber. Such situations are known to yield high error rates. Therefore, this study evaluates the effectiveness of TCM (Trellis Coded Modulation), which is an error correcting scheme.