Digital predistortion based on B-spline CPWL models in a RoF LTE mobile fronthaul

Abstract

A novel modeling and linearization model for a Radio over Fiber (RoF) LTE mobile fronthaul system is proposed in order to reduce the canonical piece-wise-linear (CPWL) model order without compromising its performance. The proposed basis is composed by cubic spline functions (B-splines basis), whose features guarantee the proposed model (BS-CPWL) accuracy when the model order is low. A 10MHz-LTE downlink signal (16QAM) is applied in order to carry out the measurements. We have experimentally demonstrated that the proposed model improves not only the modeling of the intensity modulation/direct detection (IM/DD) RoF system but also the distortion reduction, as the adjacent channel power ratio (ACPR) and error vector magnitude (EVM) values show, fulfilling the standard requirements.