| Rencent years,as the high speed service such as cloud service developed rapidly,the demand of the bandwidth of the access network is becoming urgent gradually.The coherent communication system used in long-reach optical communicaton system is quite complicate to implement.By contrast,intensity-modulation direct-detection?IM-DD?system is more adaptive in short-reach optical communication system.Meanwhile,in order to guarantee the quality and even to improve the capacity of the communication system,the digital signal processing?DSP?is necessary in the IMDD communication system,which is limited by the bandwidth of the cost-efficient component or device.In this paper,based on short-reach IMDD communication system,we ameliorate and experimentally investigate the DSP in the muli-carrier system and signal carrier system.The main works are as follows:1.An orthogonal circulant matrix transform?OCT?-based adaptive frame-level-forward error correction?FEC?scheme for fiber-visible laser light communication?VLLC?system is proposed and experimentally demonstrated in Reed-Solomon?RS?Code.In this method,no extra bits are spent for adaptive message,exc ept training sequence?TS?,which is simultaneously used for synchronization and channel estimation.In addition,the experimental results exhibit that over 20km standard single-mode fiber?SSMF?and 8m visible light transmission,and the costs of RS codewords are at most 14.12%lower than those of conventional adaptive subcarrier-RS-code based 16-QAM OFDM at bit error rate?BER?of 10-5.2.we experimentally demonstrate the intensity modulation and direct-detection?IM/DD?112-Gb/s single carrier pulse amplitude modulation?PAM?-4 transmission system over 80-km standard signal-mode fiber?SSMF?at the 3.8×10-3 BER threshold for 7%the hard-decision forward error correction?HD-FEC?.The training based pre-equalization?pre-EQ?and the nonlinear look-up-table?LUT?based pre-distortion?pre-DT?in the transmitter?Tx?-side are employed to reduce the computation complexity and deal with the modulation bandwidth and the nonlinearity impairments of electro-optical modulators and detectors.The BER is about 2×10-1 without any DSP such as equalization,pre-distortion,pre-equalization or compensation.After signal recovery,the BERs of BTB and 80-km SSMF system can achieve 3.07×10-5 and 1.50×10-3respectively.3.Research four blind quealization algorithms,constant modulus algorithm?CMA?,modified constant modulus algorithm?MCMA?,cascaded multi-modulus algorithm?CMMA?and modified cascaded multi-modulus algorithm?MCMMA?.And apply these to multi-carrier OFDM system.We experimentally demonstrate them in the VLLC 16QAM-OFDM system.The result shows that MCMMA is much more excellent than the other algorithm. |
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