Simultaneous Channel Estimation for Pulsed-Modulation Optical Wireless Communications

In this paper, suitable estimation sequences and algorithms for the simultaneous channel estimation in an optical wireless communication system are assessed. We focus on a multi-user-MISO setup and an on-off-keying based pulsed-modulation physical layer. The performance of the tested configurations is evaluated using simulations under the constraints of imperfect time synchronization between the transmitters and band-pass distortions. Furthermore, a new family of binary channel estimation sequences, named Variable Sampling Factor (VSF) sequences, is proposed with the goal of enabling simultaneous estimation even between terminals using different sample clock rates. Despite a high variance of channel gains in the used model, the best presented algorithm is able to detect 6 out of 8 transmitters on average.