Digital Predistortion for Linearity Improvement of VCSEL-SSMF-Based Radio-Over-Fiber Links

• Published in: IEEE microwave and wireless components letters Vol. 29; no. 2; pp. 155 - 157
• Main Authors: Hadi, Muhammad Usman, Traverso, Pier Andrea, Tartarini, Giovanni, Venard, Olivier, Baudoin, Genevieve, Polleux, Jean-Luc
• Format: Journal Article
• Language: English
• Published: IEEE 01.02.2019; Institute of Electrical and Electronics Engineers
• Subjects: Adjacent channel power ratio (ACPR); digital predistortion (DPD); Engineering Sciences; indirect learning architecture (ILA); Linearity; Long Term Evolution; long-term evolution (LTE); normalized mean square error (NMSE); Optics; Photonic; Predistortion; radio-over-fiber (RoF); Signal and Image processing; Training; Vertical cavity surface emitting lasers; vertical cavity surface emitting lasers (VCSELs); Wireless communication
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2018.2889004

This letter unfolds a digital predistortion (DPD) technique that improves the linearity of limited range mobile front haul links for the contemporary long-term evolution (LTE) and future (5G) networks. In particular, the proposed technique is applied to radio-over-fiber links based on single-mode (SM) vertical cavity surface emitting lasers emitting at 850 nm and standard SM fibers. Both the memory and generalized memory polynomial models are exploited for the predistorter and identified by utilizing indirect learning architecture. The impact of the DPD technique is observed by the link performance improvement in terms of normalized mean square error and adjacent channel power ratio, referring to complete LTE frames of 10 ms occupying 5-MHz bandwidth and having 64-quadrature amplitude modulation format. Furthermore, the effectiveness of the DPD approach, when varying input power levels, is investigated. The experimental results demonstrate the capability of the proposed DPD technique to achieve promising linearization performance.