Digital mobile fronthaul based on noise-coupling sturdy-multistage noise-shaping modulator

In this paper, digital mobile fronthaul (MFH) architecture enabled by noise-coupling sturdy-multistage noise -shaping (SMASH_NC) modulator is experimentally demonstrated and investigated. To verify the noise-shaping capability of the proposed SMASH_NC modulator, 12 aggregated orthogonal frequency division multiplexing (OFDM) component carriers (CCs) are firstly modulated to 4-level pulse-amplitude-modulation (PAM4) signal, and then transmitted over optical intensity modulation-direct detection (IM-DD) links. After 20 km single mode fiber (SMF) transmission, the error vector magnitude (EVM) floor of signal modulated by traditional SMASH is beyond the 512-quadrature amplitude modulation (QAM) EVM threshold of 3%, while the minimum EVMs of signal modulated by our previous proposed SMASH_FB and SMASH_NC are 1.81% and 1.16%, respectively. Compared with SMASH_FB, SMASH_NC achieves 0.6 dB receiver sensitivity improvement at 3% EVM threshold, in addition, the number of adders and multipliers can be reduced by 25% and 26.32%, respectively. To better accommodate the out-of-band leakage in the CCs aggregation, filter-bank-multicarrier (FBMC) is demonstrated and investigated with only 22.89 kHz guard band between two adjacent CCs. Compared with OFDM, the EVM floor of FBMC is successfully reduced to 0.39%, and a 0.9 dB receiver sensitivity improvement is obtained with less guard band.

Automated summary

In this paper, the digital mobile fronthaul architecture enabled by noise-coupling sturdy-multistage noise-shaping modulator is experimentally demonstrated and investigated. The noise-shaping capability of the modulator is verified by modulating orthogonal frequency division multiplexing component carriers to pulse-amplitude-modulation signal and transmitting them over optical links. The proposed modulator achieves better receiver sensitivity and reduces the number of adders and multipliers compared to previous methods. Additionally, filter-bank-multicarrier technique is demonstrated and investigated with reduced guard band and improved receiver sensitivity.