Key Technologies for Next-Generation Digital RoF Mobile Fronthaul With Statistical Data Compression and Multiband Modulation

As a counterpart of analog radio-over-fiber technology, digital radio-over-fiber (D-RoF) system, such as common public radio interface (CPRI), is a matured and robust solution to support RF signal delivery in traditional mobile fronthaul networks. In view of recent progresses in delta-sigma modulation, data compression, and advanced error correcting coding, the efficiency of D-RoF is significantly improved, which motivates researchers to re-evaluate the role of D-RoF in future mobile fronthaul networks to support 5G and beyond wireless communications. In this paper, we demonstrate two critical technologies to improve the transmission efficiency and flexibility of D-RoF systems. A fast-statistical-estimation based data compression algorithm is proposed to reduce the number of quantization digits in a D-RoF-based mobile fronthaul with low complexity and high quality. Combined with resampling and advanced modulation formats, data-transmission efficiency of a 25-Gbit/s D-RoF testbed is improved by around five times compared with uncompressed CPRI systems. On the other hand, we also experimentally demonstrate a point-to-multi-point (PTMP) D-RoF system with multiband modulation, which exhibits higher flexibility and better compatibility with multiple services and different radio-access technologies compared to existing schemes based on time interleaving. An experiment of 13.3-Gbit/s 4-band PTMP bidirectional D-RoF MFH is demonstrated. Combined with data compression, error free delivery of 6.4-Gbit/s 1024-QAM 5G-New-Radio-like signals is realized.