Investigation of a Flexible Downstream Scheme for Sampling Rate and Bandwidth Reduction in Short Reach Communication Systems

We demonstrate a cost- and spectrum-effective orthogonal frequency-division multiple access passive optical network downstream scheme based on multi-band and modified sub-Nyquist sampling over transmission reach of 20km. The sampling rate and bandwidth of ADC are reduced effectively, and double spectrum efficiency is obtained. The aggregate bit rate achieves 50.4 Gb/s. The influence of bit resolution of ADC/DAC is investigated and 8-bit resolution is regarded as a reasonable choice. The performance of receiver sensitivity and nonlinearity tolerance is studied. A 20km PON downstream transmission with splitter ratio of 1:64 is considered and the FEC limit of $3.8\times 10 ^{-3}$ is met. The research results show that the proposed scheme is suitable for the short reach communication systems and could be regarded as a promising candidate for the system beyond NG-PON2.