| Along with the development of the epoches, people’s demand of communication speed and bandwidth is increasing. Besides, the rapid development of telemedicine, video playback,internet of things and other business accelerates the requirement of the communication bandwidth. In the popularizing of global broadband, implementation "the last kilometer" by cable network cann’t keep up with the development of network, but it will restrict the development of global network bandwidth. Thus, it’s urgent to research the new type of passive optical network. Because of the good ability to resist chromatic dispersion and polarization mode dispersion, and the flexible digital signal processing on receivers, orthogonal frequency division multiple access-passive optical network(OFDMA-PON) is extremely likely to become one of the access standard for the next generation of optical access network. In this paper, we design a self-coherent system with homodyne receiver(OFDMA-PON) based on RSOA and high-order QAM modulation(32 QAM). And we conduct tests on the performance of the uplink and downlink. Then, on the uplink system receiver, the decision-auxiliary time-domain approximation algorithm is given to compensate ICI phase noise. It can also make the system reduce bit error rate under larger laser linewidth. The main research contents are as below:(1) We have proposed a novel OFDM-PON uplink transmission system based on RSOA and32 QAM. In uplink transmission, users choose different sub-carrier adaptively. To make full use of the uplink wavelength, the ONUs are divided into multiple cells closely according to their location. And the ONUs in the same cell share the same wavelength. We centralize the uplink light source in the OLT, and provide uplink wavelength for RSOA in ONU through downlink. On the uplink receiver, self-coherent system with homodyne receiver has been designed for each OFDM signal in the cell where a wavelength and multiple ONUs are shared. In order to avoid the precise synchronization of uplink OFDM signal of ONU, we transform the uplink OFDM signal of each ONU into baseband OFDM signal by optical coherent receiver, filter the signal in the electrical frequency domain, perform analog to digital conversion(ADC), and realize OFDMdemodulation through the appropriate FFT processor. In downlink transmission we use broadcasting to transmit data. With each ONU equipped with a modem, users could demodulate the information individually according to their own needs. In addition, the reliability of the system is studied in this thesis.(2) The reason to form the phase noise is analyzed, and the decision-auxiliary time-domain approximation algorithm is present. In this algorithm, signals should complete the CPE compensation firstly. The frequency part of the signals is taken into procedures of judgement and iteration over determined equations, and then compensates ICI. The signals in time domain compensate directly by ICI phase noise time-domain algorithm. After that, the frequency domain part of the results is judged again with the initial value and compensates the phase noise. Do iterate on this method. After several iterations, send the final compensation result into the QAM demodulation end for demodulating. Finally, the performance of the algorithm is analyzed in the upward direction of the 32 QAM OFDM-PON transmission system based on RSOA modulation. |
PDF Full Text Request