Blind Channel Estimation Based Positioning Enhancement for ACO-OFDM Integrated Visible Light Communication and Positioning

The integrated visible light communication and positioning (VLCP) allows simultaneous communications and the received signal strength (RSS)-based positioning, using identical signals. However, light emitting diode (LED)'s limited bandwidth and non-line-of-sight (NLoS) channels cause inter-symbol interference (ISI), having significant impact on the RSS-based positioning for VLCP systems. Therefore, we propose a blind symmetry-based channel estimation (BSCE) approach to realize high-performance communications and high-accuracy positioning, requiring no pilot. To the best of the authors' knowledge, this is the first work to investigate blind channel estimation to enhance the RSS-based positioning for asymmetrically clipped optical-orthogonal frequency division multiplexing (ACO-OFDM) VLCP systems. The symmetry structure of ACO-OFDM signals in time domain is utilized to estimate LED's limited bandwidth, line-of-sight (LoS) and NLoS channels, separately. This is different from the previous channel estimation methods that only realize the purpose of communications, estimating LED's limited bandwidth, LoS and NLoS channels together. Thus, the proposed BSCE approach enhances the RSS-based positioning accuracy much higher than the previous channel estimation works, as the RSS variation caused by LED's limited bandwidth and NLoS is mitigated. Simulation results show that the proposed BSCE approach can effectively mitigate the impact of LED's limited bandwidth and NLoS channels on positioning, and provide positioning performance higher than existing channel estimation methods.