Optimal Hexagonal Constellations Based on A Two-Dimensional Signal Space for Peak-Limited Intensity-Modulated Channels

摘要： For high-rate peak-limited intensity-modulated optical systems, the two-dimensional time-disjoint signal space (TDSS) is proposed. Based on the TDSS, the optimal hexagonal constellations (OHCs) are proposed analytically under a peak optical power constraint. Both analytical and simulation results show our proposed OHCs based on TDSS have asymptotical peak optical power gain of 0.753 dB over the baseline schemes at no extra bandwidth cost.