Polar-based OFDM and SC-FDE links toward energy-efficient Gbps transmission under IM-DD optical system constraints [Invited]
Polar-based OFDM and SC-FDE links toward energy-efficient Gbps transmission under IM-DD optical system constraints [Invited]
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DOI：
10.1364/jocn.7.00a277
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发表时间：
2015-02
期刊：
影响因子：
--
通讯作者：
H. Elgala;T. Little
中科院分区：
文献类型：
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作者：
H. Elgala;T. Little
最近的研究研究了正交频分复用（OFDM）和单载波频域均衡（SC-FDE）在每秒千兆字节（Gpbs）基于直接强度调制和直接检测（IM-DD）的短距离光纤有线和无线接入网络中的应用。OFDM系统具有固有的高峰值平均功率比（PAPR）。SC-FDE系统具有较低的PAPR，因此在各种实际考虑下，主要是在发射机有限的动态操作范围下，在误码性能方面优于同类OFDM系统。在基于射频的OFDM和SC-FDE系统中，输出信号是双极的，复杂的，并且不能在IM-DD系统中传输。因此，已经提出了几种节能方案，尽管频谱效率不高，但可以产生正OFDM和SC-FDE信号，例如，非对称剪切光OFDM （ACO-OFDM）和重复剪切光SCFDE （RCO-SCFDE）。为了提高数据速率，基于复杂符号的极性表示，提出了新的OFDM和SC-FDE信号格式，即极性OFDM （P-OFDM）和极性SC-FDE （P-SC-FDE）。该格式提供的频谱效率是目前最先进的单极OFDM和SC-FDE格式的两倍。此外，在时域正样本上采用功率分配方法，进一步降低了PAPR，并对光源功率和动态范围约束下的误码性能进行了数值评估，结果表明该方法对Gpbs传输具有较好的效果。
Recent studies have investigated the use of orthogonal frequency division multiplexing (OFDM) and single carrier frequency-domain equalization (SC-FDE) for gigabyte per second (Gpbs) short-range optical wired and wireless access networks based on direct intensitymodulation with direct detection (IM-DD). OFDM systems have an inherent high peak-to-average power ratio (PAPR). SC-FDE systems have lower PAPR and thus outperform comparable OFDM systems in terms of bit-error performance under various practical considerations, mainly the limited dynamic range of operation at the transmitter. In RF-based OFDM and SC-FDE systems, the output signal is bipolar, complex, and cannot be transmitted in IM-DD systems. Therefore, several power efficient schemes, however spectrally inefficient, have been proposed to make positive OFDM and SC-FDE signals, e.g., asymmetrically clipped optical OFDM (ACO-OFDM) and repetition and clipping optical SCFDE (RCO-SCFDE). To increase the data rate, novel OFDM and SC-FDE signal formats, called polar OFDM (P-OFDM) and polar SC-FDE (P-SC-FDE), based on a polar representation of complex symbols, are proposed. The proposed format offers twice as much spectral efficiency as state-of-the art unipolar OFDM and SC-FDE formats. Moreover, using a power allocation approach on the time-domain positive samples, the PAPR is further reduced, and the numerical evaluation of the bit-error performance under optical source power and dynamic range constraints demonstrates superior results toward Gpbs transmission.