Correlation-Based LTI Channel Estimation for Multi-Wavelength Optical Scattering Communication

Strong correlation of link gains over multiple wavelengths has been demonstrated in non-line-of-sight optical wireless scattering communication. In this paper, we further demonstrate that the channel impulse responses for different wavelengths are also strongly correlated. Thus, a novel channel estimation method based on such correlation over multiple wavelengths is proposed, where only certain reference wavelengths are assigned pilot signal. On each channel with assigned pilot signal, we adopt an improved least-squares channel estimation method to estimate the tap parameters and the tap length (or the number of taps). The channel tap coefficients on other wavelengths can be estimated based on the correlation. Under the proposed channel estimation, the channel estimation accuracy can be improved as shown by the simulations. Moreover, under the same total channel estimation overhead, the accuracy of the proposed channel estimation first increases and then decreases with the number of reference wavelengths.