Measured EVM for Radio-over-MMF

Measured EVMs of an in-vehicle RoF system which bridges 5G NR signals in the air and user terminals in a car cabin. A 28-GHz 5G NR signal generated by an arbitrary waveform generator for an IF signal generation and a signal generator used as a local oscillator is emitted through an amplifier and an transmitter (Tx) antenna. The radio-wave detected by a receiver (Rx) antenna on the roof of the car is converted into an optical signal for RoF transmission. A bend-insensitive MMF (BI-MMF) and a BI-graded-index POF (BI-GI-POF) were used for this demonstration. Fig. 4 shows measured error vector magnitudes (EVMs) for RoF transmission over a 20-m BI-MMF and a 5-m BI-GI-POF, where a reference signal was measured with a link over a 1-m coaxial cable. The receiver sensitivity was -60 dBm. The power penalty in the RoF transmission was less than 3 dB for a 64-QAM (quadrature amplitude modulation) OFDM (orthogonal frequency domain multiplexing) 5G NR signal whose bandwidth is 200 MHz.