Research And Design On Parallel Algorithm For High Speed Burst Mode Coherent Optical Receiver

With the rapid development of Internet, the traffic in the network soaring, that makes greater demands on the present backbone. The smooth evolution of optical network towards 100 Gbps system is the growing trend of high-speed optical communication system. Compared with the OFDM, PDM-QPSK is considered the mainstream modulation scheme. On the other hand, in order to meet the burst property of IP service, to make better use of wavelength and to make network flexible, OBS network is the trend of future optical network. Optical burst swithch greatly inproves resource allocation rate and utilization compared with the optical path switching, it also overcomes the restriction of optical switching and optical buffer technology of optical packet switching. Burst mode receiver running in OBS network which burst packets are transmitted in, and it needs fast initialization; besides the receiver should support high-speed digital signal processing, meanwhile, the algorithm is required to be realized, which increases the difficulty of system design too. So the DSP algorithm is the core in receiver system design.The main work of this paper is to research the DSP algorithm of the burst mode coherent optical receiver. Good parallel processing algorithm is needed due to the hardware bottlenecks in real-time implementation. A parallel algorithm which is suitable for the 112 Gbps PDM-QPSK transmission system was proposed. In order to initialize fast, parallel algorithm combined LMS and frequence offset estimation was proposed. The theoretical range of FOE result is between s?R/ 2. A scheme which using training symbols to stabilize the algorithm during date transmission was proposed. Considering the real-time implementation, calculation delay was adopted in parallel LMS algorithm, simulation and research have been done.It is necessary to increase the length of the equalizer in the longer distance transmission, which will increase the cost of system design, so two stage dispersion equalizer was adopted. One stage of frequency domain dispersion equalization to reduce the total complexity of the whole system was used. Due to the dynamic property of OBS networks, chromatic dispersion search algorithm is needed before FDE, so a simple dispersion search algorithm was introduced. Compensation in frequency domain will meet inter block interfere which should adopts overlap-cut FFT. The influence of residual dispersion and frequence offset to the system performance has been analyzed.