50Gb/s/λ速率PON系统下行传输方案及损伤抑制等关键技术研究

Efficient, flexible and low-cost PON with 50-Gb/s transmission rate is an important development trend of future optical access technology. The existing optical transmission technologies are difficult to meet the needs of future PON with high speed and wide coverage due to its disadvantages of low spectral efficiency, inflexible bandwidth allocation and high cost. The use of the transmission scheme based on the variable rate transceiver structure and distortion suppression technology in the electrical domain can effectively improve the spectral efficiency and the flexibility of bandwidth allocation of PON and reduce hardware cost. The main research work of this project include: (1) Research the efficient, flexible and low-cost PON downlink transmission scheme with 50-Gb/s transmission rate; (2) Research the impact and constraint law among the linear, nonlinear distortion caused by dispersion and IQ imbalance caused by device imperfection, then propose an adaptive suppression algorithm that can effectively compensate for IQ imbalance and the linear distortion with low complexity. Furthermore, the nonlinear distortion suppression algorithm based on pre-equalization is proposed at OLT side. (3) Establish simulation and off-line experimental platform to verify the effectiveness of the proposed transmission scheme and distortion suppression algorithm. It is proposed to realize innovation and technological breakthrough in the aspects of downlink transmission scheme, distortion suppression algorithm, system simulation and off-line experiment through the technical route that combines theoretical analysis, simulation research and experimental verification.

高效、灵活、低成本的50Gb/s/λ速率PON是未来光接入技术的重要发展方向。已有光传输技术因其频谱效率低、带宽分配不灵活、成本高等不足难以满足未来高速率、广覆盖PON的需求。利用基于可变速率收发机结构的传输方案及电域去损伤技术能够有效提高PON系统频谱效率、带宽分配灵活性并有效降低系统硬件成本。本项目主要研究内容包括：（1）研究高效、灵活、低成本的50Gb/s/λ速率PON下行传输方案；（2）研究直接检测系统中色散导致线性、非线性损伤与器件不理想导致IQ不平衡的相互影响和制约规律，提出复杂度低、自适应的IQ不平衡和信道线性损伤联合抑制算法，进一步提出OLT端基于预均衡的非线性损伤抑制算法；（3）建立仿真和离线实验平台验证所提传输方案和损伤抑制算法的有效性。通过采用理论分析、仿真研究和实验验证相结合的技术路线，拟在下行传输方案、损伤抑制算法、系统仿真与离线实验等方面实现创新和技术突破。

高效、灵活、低成本的50Gb/s/λ速率PON是未来光接入技术的重要发展方向。本项目主要针对50Gb/s/λ或更高速率PON系统下行传输方案、调制技术方案、收发机线性和非线性损伤抑制算法等展开研究，主要研究内容及获得的成果如下：.1. 提出采用Nyquist-SCM调制方案配合OLT端采用光VSB滤波的直接检测下行传输方案。所提下行传输方案有效延长了50Gb/s/λ速率PON系统的传输距离。.2. 提出面向短距离传输的低复杂度、低功耗相干接收方案。传输速率提高至100 Gb/s/λ时传统的IMDD方案将无法继续使用，此时相干接收是可靠和有效的解决方案，项目组提出2种低复杂度相干接收DSP方案，分别是：.a. 基于低速信道估计的自适应均衡架构方案.b. 高效率、低复杂度自适应均衡架构方案。 .3. 提出全数字域IQ增益和相位不平衡补偿算法。所提算法采用串联的增益和相位不平衡补偿结构、查找表辅助。.4. 提出全新的模拟和数字域联合IQ增益和相位不平衡补偿算法。所提算法架构进一步降低IQ不平衡补偿算法的复杂度。.5. 提出基于级联广义线性均衡器和Volterra均衡器的盲IQ不平衡和非线性ISI损伤抑制算法。该算法在ONU端通过DSP抑制系统线性和非线性损伤从而提高接收机灵敏度，进一步提高PON下行传输的功率预算。.6. 提出在直接检测PON系统中OLT端基于Volterra预均衡器的非线性损伤抑制算法。为了降低ONU端的复杂度和能耗，我们设计了Volterra预均衡器抑制信道中非线性ISI损伤。.7. 提出在相干PON传输中在线收发机IQ不平衡和IQ延时估计和补偿算法方案。相干PON系统中我们可以通过软件计算得到收发机的硬件不理想参数，从而能够简化收发机硬件补偿算法的复杂度。.8. 建立覆盖范围不小于40km、单波长50Gb/s速率PON下行传输模拟仿真平台和离线实验验证系统，开展仿真分析和实验研究。.9. 项目组依托该国家自然科学基金发表SCI论文9篇。