Experimental characterization of Sigma Delta Radio over fiber system for 5G C-RAN downlink

Radio over Fiber is a promising technology for the 5G Cloud Radio Access Network. We demonstrate experimentally Sigma Delta Radio over Fiber by means of Sigma Delta Modulator (SDM) subsequently replacing expensive digital to analog converters. A second order SDM is proposed for LTE 20 MHz signal having 256 QAM modulation on a carrier frequency of 3.5 GHz for 10 Km of fiber length. The performance is reported in terms of error vector magnitude, adjacent channel leakage ratio and eye-opening penalty. The results show that the proposed architecture performance is cost and power efficient solution for next-generation wireless networks. Keywords: Radio over fiber, Sigma delta modulation, 5G C-RAN, EVM, ACPR