Bandwidth-Variable Transceivers based on Four-Dimensional Modulation Formats
Bandwidth-Variable Transceivers based on Four-Dimensional Modulation Formats
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DOI：
10.1109/jlt.2014.2319244
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发表时间：
2014-04
影响因子：
4.7
通讯作者：
J. Fischer;S. Alreesh;R. Elschner;F. Frey;M. Nolle;C. Schmidt-Langhorst;C. Schubert
中科院分区：
文献类型：
--
作者：
J. Fischer;S. Alreesh;R. Elschner;F. Frey;M. Nolle;C. Schmidt-Langhorst;C. Schubert
在这篇特邀文章中，我们讨论了带宽可变收发器的技术选择，这是实现灵活的软件定义光网络的关键组件。可变带宽收发器可以根据业务需求，通过软件控制来调整传输比特率、频谱效率和透明到达等物理层参数。我们特别关注四维调制格式和调制格式透明数据辅助数字信号处理的最新进展。有人认为，在带宽可变收发器的背景下，四维调制格式对传统的极化多路复用格式是一种有吸引力的补充，在这种情况下，它们能够在频谱效率方面实现平稳过渡，同时需要少量的额外硬件工作。给出了数值模拟和实验结果支持这一说法。为了实现支持多种极化复用和四维调制格式的带宽可变收发器的低成本硬件实现，需要实现格式透明且硬件资源消耗少的数字信号处理算法。我们讨论数据辅助信号处理作为一种可能的选择，特别是关于载波频率恢复和信道估计与频域均衡相结合。
In this invited contribution, we discuss technology options for bandwidth-variable transceivers which are key components for the realization of flexible software-defined optical networking. Bandwidth-variable transceivers enable the software-controlled adaptation of physical layer parameters such as transmitted bit rate, spectral efficiency and transparent reach according to the traffic demands at hand. In particular, we focus on recent advances in four-dimensional modulation formats and in modulation format transparent data-aided digital signal processing. It is argued that four-dimensional modulation formats present an attractive complement to conventional polarization-multiplexed formats in the context of bandwidth-variable transceivers, where they enable a smooth transition with respect to spectral efficiency while requiring marginal additional hardware effort. Results of numerical simulations and experiments supporting this statement are presented. For the cost-efficient hardware implementation of bandwidth-variable transceivers supporting several polarization-multiplexed and four-dimensional modulation formats, digital signal processing algorithms are required which operate format transparent and consume little hardware resources. We discuss data-aided signal processing as one possible option, in particular with respect to carrier frequency recovery and channel estimation in combination with frequency domain equalization.