Adaptive optics 1 Digital signal processing 1 Eigenvalue and eigenfunctions 1 Eigenvalues and eigenfunctions 1 Equalizers 1 Estimation 1 Estimation methods 1 MIMO systems 1 Mean square error 1 Mode-dependent gain 1 Mode-dependent loss 1 Network-based 1 Neural networks 1 Optical coupling 1 Optical couplings 1 Optical fiber communication 1 Optical fibers 1 Optical polarization 1 Optical receivers 1 Optical signal to noise ratio 1 Optical-fiber communication 1 Signal receivers 1 Signal to noise ratio 1 Signalto- noise ratio estimations 1 Space division multiple access 1 Space division multiplexing 1 Transfer matrix method 1 mode-dependent gain 1 optical fiber communications 1 space division multiplexing 1