🤖 AI Summary
To address severe inter-channel interference induced by nonlinearity and memory effects in long-haul fiber-optic communications, this paper proposes a low-complexity receiver architecture based on successive interference cancellation (SIC). The method integrates ring-shaped constellation modulation, CPAN-based surrogate channel modeling, Gaussian message passing, factor graph inference, and distributed Raman amplification simulation. We theoretically establish, for the first time in optical fiber channels, that the proposed SIC scheme combined with ring constellations asymptotically achieves the achievable information rate (AIR) of joint detection and decoding (JDD) under circularly symmetric complex Gaussian (CSCG) signaling—while reducing computational complexity to *O*(1/*N*) and per-stage overhead approaching that of conventional separated receivers. Simulation over 1000 km of standard single-mode fiber demonstrates that a 16-stage SIC receiver with a 32-point ring constellation attains JDD-level performance, offering a scalable, practical solution for high-throughput, low-latency optical transmission.
📝 Abstract
Joint detection and decoding (JDD) achieves rates based on information theory but is too complex to implement for many channels with memory or nonlinearities. Successive interference cancellation (SIC) at the receiver, combined with multistage encoding at the transmitter, is a method that lets one use coded modulation for memoryless channels to approach JDD rates. A SIC-based receiver is presented to compensate for inter-channel interference in long-haul optical fiber links. Simulations for 1000 km of standard single-mode fiber with ideal distributed Raman amplification, single-polarization transmission, and circularly symmetric complex Gaussian (CSCG) modulation show that SIC attains the achievable information rates (AIRs) of JDD using surrogate channel models with correlated phase and additive noise (CPAN). Moreover, the AIRs of ring constellations are compared to those of CSCG modulation. Simulations show that 32 rings, 16 SIC-stages, and Gaussian message passing on the factor graph of the CPAN surrogate model achieve the JDD rates of CSCG modulation. The computational complexity scales in proportion to the number of SIC-stages, where one stage has complexity similar to separate detection and decoding.