Spectrally Efficient Direct-Detected OFDM Transmission Incorporating a Tunable Frequency Gap and an Iterative Detection Techniques
Spectrally Efficient Direct-Detected OFDM Transmission Incorporating a Tunable Frequency Gap and an Iterative Detection Techniques
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DOI：
10.1109/jlt.2009.2033304
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发表时间：
2009-12-15
影响因子：
4.7
通讯作者：
Chi, Sien
中科院分区：
文献类型：
--
作者：
Peng, Wei-Ren;Zhang, Bo;Chi, Sien
分析和实验证明了一种采用可调频隙和迭代检测技术的线性调制、直接检测的虚拟单边带正交频分复用(VSSB-OFDM)系统。无频隙的VSSB-ofdm被称为无间隙VSSB-ofdm，是一种频谱有效的格式。与强度调制的单边带OFDM相比，无间隙的VSSB-OFDM节省了一半的电带宽，并且表现出更好的接收灵敏度和对光纤色散(CD)的更强的容错性。此外，通过在光载波和OFDM数据边带之间加入一个可调的频差，大大减轻了迭代检测的计算负担，在适度的迭代中可以灵活地提高系统性能。最佳频隙的宽度类似于0.35边带带宽，这是通过交换信号-信号拍频干扰和残余图像拍频干扰的电平而达到的。与无间隙VSSB-ofdm系统相比，这种有间隙的VSSB-ofdm系统需要更少的迭代来从干扰信号中提取期望的数据，并且表现出更强的抗载波信噪比(CSPR)变化的鲁棒性。在这篇论文中，我们将会提出有间隔的VSSB-ofdm系统的解析模型。此外，我们还成功地在1600公里的无补偿标准单模光纤(SSMF)上成功地传输了有间隙的VSSB-ofdm信号，而仅有类似于3dB光信噪比(OSNR)的代价，并且在这样一条1600公里的光纤链路之后，与无间隙VSSB-ofdm相比，获得了8db的显著的OSNR灵敏度提升。
We analytically and experimentally demonstrate a linearly field-modulated, direct-detected virtual single-side-band orthogonal frequency-division multiplexing (VSSB-OFDM) system that employs a tunable frequency gap and an iterative detection technique. The VSSB-OFDM that uses no frequency gap, which is referred to as the gapless VSSB-OFDM, is proposed as a spectrally efficient format. Compared with the intensity-modulated SSB-OFDM, the gapless VSSB-OFDM saves half the electrical bandwidth (BW), and exhibits better receiving sensitivity and more robust tolerance against fiber chromatic dispersion (CD). Furthermore, by incorporating a tunable frequency gap between the optical carrier and the OFDM data sideband, the calculating burden of the iterative detection is greatly alleviated and the system performance can be flexibly improved within moderate iterations. The width of the optimum frequency gap is found to be similar to 0.35 sideband BW, which is reached by trading the levels of signal-signal beat interference and the residual image beat interference. Such a gapped VSSB-OFDM system requires fewer iterations to extract the desired data from the interfered signal and exhibits greater robustness against the carrier-to-signal-power ratio (CSPR) variation, compared with the gapless VSSB-OFDM. In this paper, the analytical model of the proposed gapped VSSB-OFDM system will be addressed. In addition, we also successfully conduct a gapped VSSB-OFDM signal transmission over 1600 km of uncompensated standard single-mode fiber (SSMF) with only similar to 3 dB optical SNR (OSNR) penalty, and obtain a significant OSNR sensitivity improvement of 8 dB, compared with the gapless VSSB-OFDM, after such a 1600-km fiber link.