Research On Upstream Transmission Of Passive Optical Network Based On OGDM

With the advent of the information age, the demand for multi-service is on the increase and the higher requirements for bandwidth are expected. In the development process of access network process, a problem that how to improve the transmission bandwidth and transmission quality of the access network with considering lower cost and feasibility of maintenance, is presented. With the advent of optical access network(OAN), there is no doubt that it will be a breakthrough.In this paper, we propose a new multiplexing technology applying to the upstream transmission of passive optical network system——orthogonal graph division multiplexing passive optical network(OGDM-PON). In the proposed scheme, different ONUs are distinguished by the orthogonally among different waveforms. In OGDM-PON system, the same wavelength lasers are assigned to all ONU, each ONU is assigned a unique electrical waveform, which is mutually orthogonal with each other. In each ONU, two-stage modulation is applied. In the first stage, data of each ONU is modulated on the electrical orthogonal waveforms. In the second stage, the modulated electrical orthogonal waveforms are respectively modulated onto the optical carriers with same wavelength. At the OLT, after photoelectric conversion, we use the related operation to demodulate the combined signals of different ONUs. Simulation and experiment are carried out to investigate the performance of OGDM-PON.In simulation, we use MATLAB to generate multiple mutually orthogonal waveforms, and then use externally intensity modulation to modulate the orthogonal waveforms onto optical carries in VPItransmissionMaker. In receiving end, after photo-electric detection by PD, the correlation calculation is performed between the received signals and local signals. And then through the decision, we recover the original signals of each ONU. The tested results shows that the bit error rate(BER) is less than 10-4 at 10Gb/s rate after 90 km transmission. At the transmitter of experiment, FPGA and DAC are used to achieve the output signals. And at the receiver, FPGA and ADC are used for correlation demodulation. In the case of the bit error rate less than 10-4, the receiving sensitivity of 3-way ONU at 100Mb/s rate of transmission after 40 km transmission is-13.9dBm, which verifies the feasibility of OGDM-PON.