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

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.

[1]  J. Corral,et al.  Transmission Over SSMF at 850 nm: Bimodal Propagation and Equalization , 2017, Journal of Lightwave Technology.

[2]  F.M. Ghannouchi,et al.  Deembedding static nonlinearities and accurately identifying and modeling memory effects in wide-band RF transmitters , 2005, IEEE Transactions on Microwave Theory and Techniques.

[3]  R. Beresford.  ASKAP photonic requirements , 2008, 2008 International Topical Meeting on Microwave Photonics jointly held with the 2008 Asia-Pacific Microwave Photonics Conference.

[4]  Catherine Algani,et al.  VCSEL-Based Radio-Over-G652 Fiber System for Short-/Medium-Range MFH Solutions , 2018, Journal of Lightwave Technology.

[5]  Jaehyeong Kim,et al.  A Generalized Memory Polynomial Model for Digital Predistortion of RF Power Amplifiers , 2006, IEEE Transactions on Signal Processing.

[6]  Olivier Venard,et al.  On the system level convergence of ILA and DLA for digital predistortion , 2012, 2012 International Symposium on Wireless Communication Systems (ISWCS).

[7]  G. Meslener,et al.  Chromatic dispersion induced distortion of modulated monochromatic light employing direct detection , 1984 .

[8]  Nathan J. Gomes,et al.  Predistortion of Radio Over Fiber Links: Algorithms, Implementation, and Measurements , 2012, IEEE Transactions on Circuits and Systems I: Regular Papers.

[9]  Pierpaolo Boffi,et al.  Very high-capacity short-reach VCSEL systems exploiting multicarrier intensity modulation and direct detection. , 2016, Optics express.

[10]  Lei Guan,et al.  Optimized Low-Complexity Implementation of Least Squares Based Model Extraction for Digital Predistortion of RF Power Amplifiers , 2012, IEEE Transactions on Microwave Theory and Techniques.

[11]  Idelfonso Tafur Monroy,et al.  Performance evaluation for DFB and VCSEL-based 60 GHz radio-over-fiber system , 2013, 2013 17th International Conference on Optical Networking Design and Modeling (ONDM).

[12]  G. Tartarini,et al.  Digital predistortion technique for the compensation of nonlinear effects in radio over fiber links , 2016, 2016 IEEE 2nd International Forum on Research and Technologies for Society and Industry Leveraging a better tomorrow (RTSI).