Joint data transmission and dimming control optimization for MIMO–VLC systems with channel-adaptive spatial constellation design

Abstract

In the field of indoor wireless communications, visible light communications (VLCs) have attracted great attention for synergistically providing both illumination and data transmission. Meanwhile, multiple-input multiple-output (MIMO) technique has been applied in VLC systems to boost data rate by utilizing spatial resources. However, different geometrical locations of transceivers provide distinct optical channels which may effect the performance of the conventional MIMO–VLC techniques severely. In this paper, we propose the channel-adaptive spatial constellation (CASC) design for the MIMO–VLC systems by fully taking advantage of the channel state information (CSI), where the optimal transmitted signal constellation can be constructed via maximizing the minimum Euclidean distance (MED) of the received signal constellation. Meanwhile, the practical lighting constraints are taken into consideration with the non-linearity characteristic of light-emitting diode (LED) and the dimming requirements to maintain a specific indoor illumination level. Finally, simulations results indicate that the proposed CASC design can achieve significant improvement of error performance compared with the conventional MIMO–VLC schemes.