Phase-Noise Compensation for Space-Division Multiplexed Multicore Fiber Transmission
Higher-order modulation formats have also garnered attention in recent years as they allow for a higher spectral efficiency, an important parameter that relates to the throughput of communication systems. However, a drawback with increasing the order of modulation formats is the added sensitivity to phase noise, which calls for effective phase-noise compensation (PNC). This thesis studies the idea of sharing processing resources to increase the performance of PNC in SDM systems using a particular type of fiber, namely uncoupled, homogeneous, single-mode MCF.
Phase noise can be highly correlated across channels in various multichannel transmission scenarios, e.g., SDM systems utilizing MCFs with all cores sharing the same light source and local oscillator, and wavelength-division multiplexed systems using frequency combs. However, the nature of the correlation in the phase noise depends on the system in question. Based on this, a phase-noise model is introduced to describe arbitrarily correlated phase noise in multichannel transmission. Using this model, two pilot-aided algorithms are developed using i) the sum–product algorithm operating in a factor graph and ii) variational Bayesian inference. The algorithms carry out joint-channel PNC and data detection for coded multichannel transmission in the presence of phase noise. Simulation results show that in the case of partially-correlated phase noise, they outperform the typical PNC approach by a wide margin. Moreover, it is shown that the placement of pilot symbols across the channels has a considerable effect on the resulting performance.
Focusing on SDM transmission through an uncoupled, homogeneous, single-mode MCF with shared light source and local oscillator lasers, the performance benefits of joint-channel PNC are investigated. A significant gain in transmission reach is experimentally demonstrated, and the results are shown to agree strongly with simulations based on the introduced phase-noise model. In addition, the simulations show that dramatic improvements can be made for phase-noise limited systems in terms of power efficiency, spectral efficiency, and hardware requirements.
Coherent fiber-optic communications
Chalmers, Elektroteknik, Kommunikations- och antennsystem, Kommunikationssystem
A. F. Alfredsson, E. Agrell, and H. Wymeersch, “Iterative detection and phase-noise compensation for coded multichannel optical transmission”
A. F. Alfredsson, E. Agrell, H. Wymeersch, and M. Karlsson, “Pilot distributions for phase tracking in space-division multiplexed systems”
A. F. Alfredsson, E. Agrell, H. Wymeersch, B. J. Puttnam, G. Rademacher, R. S. Luís, and M. Karlsson, “On the performance of joint-channel carrier-phase estimation in space-division multiplexed multicore fiber transmission”
Informations- och kommunikationsteknik
Chalmers tekniska högskola
EDIT Building, Room EC
Opponent: Robert Killey, UCL Electronic & Electrical Engineering, UK