Pre-Equalized DMT Signal Transmission Utilizing Low-Resolution DAC With Channel Response Dependent Noise Shaping Technique

In this paper, a channel response dependent noise shaping (CRD-NS) technique is proposed and experimentally demonstrated for the pre-equalized discrete multi-tone (DMT) signal transmission in intensity modulation and direct detection (IM/DD) system with a low-resolution digital-to-analog converter (DAC). Compared with traditional NS technique, the proposed CRD-NS technique can bring signal-to-quantization noise ratio (SQNR) improvement and solve the unevenly distributed SQNR problem in pre-equalized DMT signal induced by residual quantization noise without introducing additional computational complexity. Transmission and reception of 100 Gb/s 16 quadrature amplitude modulation (QAM)-DMT signal generated by a 3-bit DAC are experimentally demonstrated to verify the effectiveness of the proposed CRD-NS technique. The experimental results show that the bit-error ratio (BER) performance of 100 Gb/s 16 QAM-DMT signal with CRD-NS technique outperforms the corresponding signal with traditional NS technique. Compared with digital resolution enhancer (DRE) technique, in which channel response is also considered, the CRD-NS technique shows a similar noise shaping capability with DRE in pre-equalized DMT signal transmission, while the computational complexity can be significantly reduced, the number of real multiplications per sample is reduced from 81 to 7.