Real-time upstream services demonstration in orthogonal frequency division multiplexing-passive optical network system

Real-time digital service and multimedia service upstream transmission in Digital Signal Processing (DSP)-based Orthogonal Frequency Division Multiplexing-Passive Optical Network (OFDM-PON) is experimentally demonstrated with Centralised Light Source (CLS) configuration in this paper. After transmitted over 25 km Standard Single Mode Fibre (SSMF) with -16.5 dBm optical power at receiver, the Bit Error Rate (BER) is 9.5 × 10^-11. The implementations of digital domain up-conversion and down-conversion based on Field Programmable Gate Array (FPGA) are introduced, which can reduce the cost of In-ph-ase and Quadrature (IQ) radio frequency mixers utilised at transmitter and receiver. A carrier synchronization algorithm is implemented for compensating carrier offset. A channel equalization algorithm is adopted for compensating the damage of channel. A new structure of Frequency Synchronization Unit (FSU) designed in FPGA is also proposed to cope with the frequency shifting at receiver.