Comparison of single-lane 100 Gb/s PAM-4 and DB-PAM-4 signals transmission based on 12G receiver with FFE and LDPC

Abstract

Abstract Using low-bandwidth receivers to transmit single-wavelength 100\xa0Gb/s data provides a low-cost and high-rate solution for the next generation passive optical networks (PONs). In this paper, we experimentally investigate the transmission of single-wavelength 100 \xa0Gb/s four-level pulse–amplitude modulation (PAM-4) and duobinary PAM-4 (DB-PAM-4) signal with a cost-effective 12\xa0GHz PIN receiver. Feed-forward equalization (FFE) in conjunction with low-density parity-check (LDPC) is applied to enhance the bit error rate (BER) performance of the 25-km standard single-mode fiber (SSMF) transmitted signal. The Max-Log-maximum a posteriori (MAP) algorithm is utilized to computing soft information and provide it to LDPC decoding. As a result, under the same limited-bandwidth transmission conditions, DB-PAM-4 shows superior performance compared to PAM-4, reducing BER below the LDPC threshold 1 0 − 2 . Error-free 25\xa0km-transmission of 100 Gb/s DB-PAM-4 signal is realized employing 35-tap FFE and LDPC. On the contrast, the BER of PAM-4 cannot even be lower than 1 0 − 1 , even with more taps and longer training sequences.