BER FSO Kramers–Kronig receiver MIMO adaptive equalizer MMSE OOK Raman amplification action recognition atmospheric turbulence blocking matrix coherent fiber optic communications coherent optical communication computer vision convolutional neural network deep neural network deformation model depth sensor dispersion engineering energy harvesting fractional-spaced equalizer (FSE) geodesic features global features hand pose tracking human representation interference-plus-noise covariance matrix reconstruction inverse design joint estimation matched filter n/a nonlinear distortion