Power margin improvement for OFDMA-PON using hierarchical modulation.
Power margin improvement for OFDMA-PON using hierarchical modulation.
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DOI：
10.1364/oe.21.008261
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发表时间：
2013-04
期刊：
影响因子：
3.8
通讯作者：
Pan Cao;Xiaofeng Hu;Zhiming Zhuang;Liang Zhang;Q. Chang;Qi Yang;Rong Hu;Yikai Su
中科院分区：
文献类型：
--
作者：
Pan Cao;Xiaofeng Hu;Zhiming Zhuang;Liang Zhang;Q. Chang;Qi Yang;Rong Hu;Yikai Su
我们提出并实验证明了一种分层调制方案，以提高正交频分多址无源光网络（OFDMA-PON）的功率裕度。在PON系统中，在相同的发射光功率下，光网络单元（Optical Network Unit，ONU）由于分配光纤长度的不相等而具有不同的功率裕度。PON系统的功率裕度由具有最低功率裕度的ONU确定。在我们提出的方案中，ONU与长和短的分布光纤分组在一起，和成对的ONU的下行信号映射到相同的OFDM子载波使用分层调制。在一对ONU中，具有短分布光纤的ONU的部分功率余量被重新分配给具有长分布光纤的ONU。因此，可以增加具有最长分布光纤的ONU的功率裕度，导致PON系统的功率裕度改善。实验结果表明，分层调制方案使OFDMA-PON系统的功率裕度提高了2.7 dB，可用于支持更多用户或扩展传输距离。
We propose and experimentally demonstrate a hierarchical modulation scheme to improve power margin for orthogonal frequency division multiple access-passive optical networks (OFDMA-PONs). In a PON system, under the same launched optical power, optical network units (ONUs) have different power margins due to unequal distribution fiber lengths. The power margin of the PON system is determined by the ONU with the lowest power margin. In our proposed scheme, ONUs with long and short distribution fibers are grouped together, and downstream signals for the paired ONUs are mapped onto the same OFDM subcarriers using hierarchical modulation. In a pair of ONUs, part of the power margin of the ONU with short distribution fiber is re-allocated to the ONU with long distribution fiber. Therefore, the power margin of the ONU with the longest distribution fiber can be increased, leading to the power margin improvement of the PON system. Experimental results show that the hierarchical modulation scheme improves the power margin by 2.7 dB for an OFDMA-PON system, which can be used to support more users or extend transmission distance.