Abstract In the 10 GSymbol/s/ λ coherent PON downlink system with I- and Q-axis mapping for different optical node units (ONUs), an extra power transmission happens because of the transmission difference between the ONUs. An adaptive IQ imbalance modulation with optimum IQ power loading for two ONUs is introduced at the transmitter-side digital signal processing (DSP). For scaling of the IQ power ratio setting range, DD-CPR with PADE scheme as an accurate frequency offset compensation is used at the receiver-side DSP. We numerically and experimentally show 2.8 dB power saving compared to a conventional balanced QPSK signal using the adaptive IQ imbalanced QPSK signal ( θ = π /12) in the case of the 57 km downlink transmission difference between two ONUs.

中文翻译：

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具有接入段长度差的相干PON下行系统的决策导向CPR辅助IQ不平衡复用

摘要 在10 GSymbol/s/λ相干PON下行链路系统中，不同光节点单元（ONU）的I轴和Q轴映射，由于ONU之间的传输差异，会产生额外的功率传输。在发射器侧数字信号处理 (DSP) 中引入了具有两个 ONU 最佳 IQ 功率负载的自适应 IQ 不平衡调制。为了缩放 IQ 功率比设置范围，在接收器侧 DSP 中使用带有 PADE 方案的 DD-CPR 作为精确的频率偏移补偿。在两个 ONU 之间的下行链路传输距离为 57 km 的情况下，我们通过数值和实验表明，与使用自适应 IQ 不平衡 QPSK 信号（θ = π /12）的传统平衡 QPSK 信号相比，功率节省了 2.8 dB。