Abstract :
Decreased performance system on Long Term Evolution (LTE) technology due to nonlinear
effect that occurs on the use of input power of 2, 4, and 6 dBm. The Orthogonal Frequency
Division Multiplexing (OFDM) system - Radio Over Fiber (RoF) is used as the most effective
solution to overcome the shortcomings of the technology. In this research, the model design for
OFDM-RoF system uses single-port dual polarization method with QPSK and QAM modulation
using OptiSystem software. The OFDM-RoF design uses 128 subcarriers, 40 Gbps bitrates, 0.2
dB/km attenuation, 16.75 ps/nm dispersion, and 193,1 THz Laser frequency. The design on the
transmitter uses an external modulation technique with a CW Laser source and a modulator of the
Mach-Zehnder modulator, on the transmission side using optical fiber and optical fiber at 50 km
optical fiber length while at the receiving end using coherent detection with PIN. The tests were
conducted with variation of input power (2 dBm, 4 dBm, and 6 dBm) and variation of fiber optic
length (50 km, 100 km, 150 km, and 200 km). Based on the results of the research, the use of 6
dBm input power on 50 km long fiber has the best performance with EVM value of 6,629 for
QPSK and 6,875 for QAM, receiving power -17,823 dBm for QPSK modulation and -17.872dBm
for QAM modulation, and BER value of 0. the worst of the work happened on 2 dBm power usage
and 200 km fiber length, which has EVM 75,024 for QPSK and 84,564 dBm for QAM, received
power -49.836 dBm for QPSK and -49.865 dBm for QAM, and BER value 39.26 x 10-2.
Keywords: OFDM-RoF, QPSK, QAM, BER, EVM,Output Power.