Pilot-Aided Channel Estimation on SC-PAM Based Visible Light Communications

Estimation of the time-varying optical wireless channel response is crucial in order to decode received signals coherently. In this work, we investigate symbol-error-rate and mean absolute error performance of different interpolation techniques including linear, nearest, spline, and piece-wise cubic Hermite interpolating polynomial (pchip), which are used in pilot-aided channel estimation process for visible light communication. The performance of interpolators is evaluated in realistic time-varying channel model, generated on Zemax software and compared with each other under the consideration of different modulation orders, different pilot symbol periods, and different user equipment (UE) speeds through Monte Carlo simulations. The results reveal that spline and pchip techniques are more robust to low pilot symbol transmission rate and fast time-varying channel conditions as a consequence of high UE speeds. However, low complex linear interpolation technique can be chosen for highly rated pilot signal transmission cases or when optical channel varies slowly over the time.