Aligning the Light Without Channel State Information for Visible Light Communications Articles uri icon

publication date

  • January 2018

start page

  • 91

end page

  • 105

issue

  • 1

volume

  • 36

International Standard Serial Number (ISSN)

  • 0733-8716

Electronic International Standard Serial Number (EISSN)

  • 1558-0008

abstract

  • The use of light-emitting diodes (LEDs) for ambient illumination leads to visible light communications (VLC) as a promising technology for providing both constant lighting and high-speed wireless services in indoor environments. Since multiple LED sources can be transmitted to several users, this scenario naturally forms a multiple-user multiple-input single-output system. In this sense, transmit precoding (TPC) schemes based on channel state information at the transmitter (CSIT) originally devised for radio-frequency (RF) systems have been proposed for their implementation in VLC. However, beyond providing CSIT or the need for cooperation among transmitters, which also result challenging in RF systems, there are several constraints such as the non-negativity of the transmitted signal or providing constant illumination that hamper the performance of TPC schemes in VLC. Considering these constraints, this paper explores the use of blind interference alignment (BIA) for achieving multiplexing gain without CSIT or cooperation among LED lights. To do that, we devise the concept of reconfigurable photodetector that allows switching among distinct and linearly independent channel responses. Simulation results show that the use of BIA in VLC systems schemes based on the proposed reconfigurable photodetector results suitable for VLC systems.

keywords

  • visible light communications; optical MIMO; precoding; blind interference alignment; reconfigurable photodetector; channel state information