Hybrid OFDM-digital filter multiple access (OFDM-DFMA) PONs exploit software configurable digital shaping filters in ONUs to multiplex multiple gapless OFDM channels at different radio frequencies and utilize a single FFT operation-based pipelined DSP procedure in the OLT to simultaneously de-multiplex/demodulate all OFDM signals from various ONUs without requiring any digital matching filters. In this letter, aggregated raw 30Gbit/s over 25km multipoint-to-point upstream signal transmissions of IMDD OFDM-DFMA PONs are experimentally demonstrated for the first time. Experimental results show that a reduction in ONU-embedded digital filter length from 256 to 16 just decreases the receiver sensitivity by < 1 dB, which are independent of ONU spectral locations. By utilizing a digital filter length as short as L=16L=16 , fibre transmission impairments (channel interference) are shown to give < 1 dB (< 2.5 dB) receiver sensitivity degradations. In addition, a >3.5dB (>5.5 dB) ONU launch power dynamic range is also achievable for an aggregated upstream transmission raw capacity of 28.12Gbit/s (23.43Gbit/s).

中文翻译：

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混合 OFDM-数字滤波器多址 PON 的实验演示


混合 OFDM 数字滤波器多址 (OFDM-DFMA) PON 利用 ONU 中的软件可配置数字整形滤波器来复用不同射频下的多个无间隙 OFDM 信道，并在 OLT 中利用单个基于 FFT 操作的流水线 DSP 程序来同时解复用/解调来自各个 ONU 的所有 OFDM 信号，无需任何数字匹配滤波器。在这封信中，首次通过实验演示了 IMDD OFDM-DFMA PON 的 25 公里多点对点聚合原始 30Gbit/s 上行信号传输。实验结果表明，将ONU嵌入式数字滤波器长度从256减少到16只会使接收器灵敏度降低< 1 dB，这与ONU频谱位置无关。通过利用长度短至 L=16L=16 的数字滤波器，光纤传输损伤（信道干扰）会导致接收器灵敏度降低 < 1 dB (< 2.5 dB)。此外，对于 28.12Gbit/s (23.43Gbit/s) 的聚合上行传输原始容量，还可以实现 >3.5dB (>5.5 dB) ONU 发射功率动态范围。