Analytical Study and Noise Mitigation for Complex-Valued Optical DSB Transmission With Carrier-Assisted Differential Detection Receiver

A thorough analysis of the system model for complex-valued optical double-sideband (DSB) transmission with carrier-assisted differential detection (CADD) receiver under the influence of laser phase noise and fiber chromatic dispersion (CD) is presented. It is shown that the interaction of laser phase noise and CD leads to the phenomenon of phase-to-amplitude (P2A) noise and equalization-enhanced phase noise (EEPN). The achievable performance of the complex-valued optical DSB transmission with CADD receiver under the influence of EEPN and P2A noise is estimated by a closed-form expression, and it is verified by simulation that the results show an inaccuracy of less than 1 dB for a wide range of system parameters. In addition, in order to mitigate the EEPN and P2A noise, we propose a pre-decision aid-based simplified blind phase search (BPS) algorithm, commonly referred to as PDA-BPS algorithm. The PDA-BPS algorithm allows for reduced complexity by decreasing the number of symbols entering the BPS algorithm. Theoretical derivation and simulation verification illustrate that the PDA-BPS algorithm can achieve similar mitigation performance to the BPS algorithm with lower complexity. Specifically, under the condition that classification decision threshold
$R$
is equal to 0.25, the complexity can be reduced by 40%/16.6% with 1 MHz/7 MHz linewidth for 16-QAM and 29%/10.9% with 0.5 MHz/3 MHz linewidth for 64-QAM.