This process reduces the OOB emissions, making fragmented spectrum dynamic spectrum allocation feasible without severe interference. The subcarriers are filtered with a prototype filter that is crucial shifted in time domain and frequency domain. In 2009, researchers provided a new modulation scheme-Generalized Frequency Division Multiplexing, which is a block based multi carrier technique with non-rectangular pulse shaping filter to improve frequency localization of pulse, it can achieve low out-of-band (OOB) emission, high spectral efficiency and low PAPR, becoming a potential alternative for the next generation networks.
However, some drawbacks are inevitable, such as high out-of-band emission, high Peak Average Power Ratio (PAPR) and sensitive to frequency offset. Due to the advantages of flexibility, simple structure and easy implementation, robustness against Inter-Symbol interference (ISI) and Inter-Carrier interference (ICI) in multipath channels, OFDM in RoF system has been deeply studied in the past two decade years. Over the past decades years, Radio over Fiber system has widespread application foreground with multicarrier which owe the advantages of wide bandwidth, high data rate and low power consumption. In the end of the paper, we analyze the performance of the proposed RoF system and be verified through MATLAB and Optisystem joint simulation that the proposed GFDM scheme with LDPC-GS-16QAM outperforms GFDM scheme with regular 16QAM by at least 15.3dB at bit error rate (BER) of 10 −5. Furthermore, we study the bit error rate performance of the proposed scheme combined with low density parity check (LDPC) codes. The transmission distance through single mode fiber (SMF) is 16km. They were then transmitted onto carriers with a frequency of 60GHz by a quadrature modulator, the central frequencies of the two signals are 60GHz, 70GHz respectively. The frequency interval between the two signals is 10GHz. The transmission signals consist of a GFDM signal and a OFDM signal with bandwidth of 5GHz and 2.5GHz respectively. In this paper, Radio over Fiber (RoF) system of generalized frequency division multiplexing (GFDM) and orthogonal frequency division multiplexing (OFDM) based on geometric shaping (GS) 16QAM is established on MATLAB and Optisystem platform.