Experimental evaluation of digital predistortion for VCSEL-SSMF-based Radio-over-Fiber link

This article proposes a Digital Predistortion (DPD) technique in order to enhance the linearity of short and limited range Mobile Front Haul (MFH) links for the present Long-Term Evolution (LTE) and future (5G) cellular networks. The proposed technique is applied to 850 nm Single Mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single-Mode Fibers (SSMFs) low cost and low consumption Radio-over-Fiber (RoF) link. Memory Polynomial is employed using Indirect Learning Architecture (ILA). Moreover, the resilience of the DPD approach to changes in input power levels is investigated. The improvements in the quality of the received signal due to the proposed solution are illustrated with reference to scenarios of applicative interest. The performance of proposed technique is evaluated in terms of Adjacent Channel Power Ratio (ACPR) and Normalized Mean Square Error (NMSE) for entire LTE frame of 10ms for 5 MHz band signal having 64 QAM modulation format.