Mobile channel estimation based on decision feedback in vehicle-to-infrastructure visible light communication systems

Visible light communication (VLC) emerges as a promising candidate in vehicle-to-infrastructure (V2I) networks. For VLC downlink between street lamps and a mobile vehicle, received signals tend to experience a time-varying multi-source and multi-path channel condition. This will affect the effectiveness of channel equalization when assuming constant channel characteristics within each data packet. In this paper, in order to track the time-varying mobile VLC channel effectively, we propose a channel estimation method for V2I downlink based on decision feedback with orthogonal frequency division multiplexing. Considering different system parameters, extensive numerical experiments are carried out. Results show that compared with the conventional scheme using only training sequences, adopting decision feedback can achieve higher channel estimation accuracy, thus improving link performance significantly. For vehicle velocity at 15 m/s, bit error rate (BER) < 10 ⁻⁴ can be achieved at ∼199 Mbps if transmit power per lamp is > 30 W. Moreover, the proposed method is almost unaffected by the change of vehicle moving state, with stable BER achieved.