Shieh W, Yang Q, Ma Y
ARC Special Research Centre for Ultra-Broadband Information Networks and National ICT Australia, Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia.
Opt Express. 2008 Apr 28;16(9):6378-86. doi: 10.1364/oe.16.006378.
Coherent optical OFDM (CO-OFDM) has emerged as an attractive modulation format for the forthcoming 100 Gb/s Ethernet. However, even the spectral-efficient implementation of CO-OFDM requires digital-to-analog converters (DAC) and analog-to-digital converters (ADC) to operate at the bandwidth which may not be available today or may not be cost-effective. In order to resolve the electronic bandwidth bottleneck associated with DAC/ADC devices, we propose and elucidate the principle of orthogonal-band-multiplexed OFDM (OBM-OFDM) to subdivide the entire OFDM spectrum into multiple orthogonal bands. With this scheme, the DAC/ADCs do not need to operate at extremely high sampling rate. The corresponding mapping to the mixed-signal integrated circuit (IC) design is also revealed. Additionally, we show the proof-of-concept transmission experiment through optical realization of OBM-OFDM. To the best of our knowledge, we present the first experimental demonstration of 107 Gb/s QPSK-encoded CO-OFDM signal transmission over 1000 km standard-single- mode-fiber (SSMF) without optical dispersion compensation and without Raman amplification. The demonstrated system employs 2x2 MIMO-OFDM signal processing and achieves high electrical spectral efficiency with direct-conversion at both transmitter and receiver.
相干光正交频分复用（CO-OFDM）已成为即将到来的100 Gb/s以太网中一种有吸引力的调制格式。然而，即使是CO-OFDM的频谱高效实现也需要数模转换器（DAC）和模数转换器（ADC）在当前可能无法获得或不具有成本效益的带宽下运行。为了解决与DAC/ADC设备相关的电子带宽瓶颈问题，我们提出并阐明了正交频带复用OFDM（OBM-OFDM）的原理，即将整个OFDM频谱细分为多个正交频带。采用该方案，DAC/ADC无需以极高的采样率运行。还揭示了与混合信号集成电路（IC）设计的相应映射关系。此外，我们通过OBM-OFDM的光学实现展示了概念验证传输实验。据我们所知，我们首次进行了107 Gb/s QPSK编码的CO-OFDM信号在1000 km标准单模光纤（SSMF）上的传输实验，无需光色散补偿和拉曼放大。所展示的系统采用2x2 MIMO-OFDM信号处理，并在发射机和接收机处通过直接转换实现了高电子频谱效率。
