Combinational Code for Channel Estimation in Visible Light Communications and Positioning

Abstract

In visible light communications (VLC) and visible light positioning (VLP), channel gains between receiver and light sources are required to be estimated. Although Time Division Multiple Access (TDMA) is typically used in the channel estimation phase of radio frequency systems, it may not be applicable for VLC and VLP systems due to the maximum power constraint and desired average power constraint that are unique to visible light systems. Recently, combinational code has been proposed as a coding scheme for channel estimation in VLC and VLP. Combinational code can work under the maximum and average power constraints, and it minimises the total and maximum noise variances experienced by the receiver. This paper reports some experimental results to compare combinational code and two schemes based on TDMA. Experimental results show that in terms of noise variance experienced by a receiver, combinational code significantly outperforms other schemes based on TDMA under the same power constraints. Challenges encountered in experiments for channel estimation are discussed and solutions are suggested to overcome these challenges.