| 摘要 |
A coded multidimensional modulation system called generalized OFDM (GOFDM) uses orthogonal subcarriers as bases functions, and the signal constellation points of corresponding multidimensional constellation diagram are obtained as N-dimensional Cartesian product of one-dimensional PAM/two-dimensional QAM. In GOFDM, the N-dimensional/2N-dimensional signal constellation point is transmitted over all N subcarriers/2N-subcarriers, which serve as individual bases functions. Even if some of the subcarriers are severely affected by channel distortion, the overall signal constellation point will face only small distortion, when strong channel capacity achieving channel codes are used. In addition, because the channel capacity is a linear function of number of dimensions, the spectral efficiency of optical transmission systems is significantly improved. Finally, since Euclidean distance of multidimensional signal constellation is much larger that that of two-dimensional signal constellations, OSNR sensitivity is dramatically improved.
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