The Future of Wireless Light Communication

Abstract

Networked visible light communications -also referred to as Li-Fi- are an exciting new field of development in communications. This talks looks at practical applications of Li-Fi and discusses its future. Li-Fi, promises quantum step improvements in area spectral efficiency while exploiting existing infrastructures by piggy-backing high speed data communication on existing lighting infrastructures. The visible light spectrum is unlicensed and 10,000 times larger than the range of radio frequencies between 0 Hz to 30 GHz. The use of the visible light spectrum for data communication is enabled by inexpensive and off-the-shelf available light emitting diodes (LEDs) which also form the basis for next generation energy efficient lighting. Individual LEDs can be modulated at very high speeds - 3.5Gbit/s @ 2m distance have been demonstrated as well as 1.1Gbit/s @ 10m at the University of Edinburgh. Both demonstrations use micro LEDs with a total optical output power of 5 mW. LED lighting saves energy, and combining lighting and data communication adds additional energy saving benefits. Moreover, transforming the multiple light fixtures in a room into networked optical access points enables high density wireless networking referred to as optical attocell networks. While in radio frequency (RF) communication, multiple antennas as well as multiple transmission chains are required to achieve beamforming, this can simply be accomplished in Li-Fi by optical lenses.Because of this feature and the fact that light is spatially contained (and does not propagate through walls), effective interference management in high density optical attocell networks does not involve large computational complexity und very dense deployment of optical attocells is practically feasible. A by-product of the interference containment is enhanced security which could be exploited for new cybersecurity techniques. Recent research has shown that the area spectral efficiency in-doors can be improved by a factor of 900 when using an optical attocell network. Thus it is possible to harness a vast and licence-free wireless transmission resource with existing devices, design optical access points to enable a new level of network densification without creating an unmanageable interference problem, thereby giving Li-Fi the capability to address jointly the issues of wireless data crunch, energy efficiency, security and simple transceivers for the large scale deployment of wireless devices. In this talk, we summarize recent trends and look at the future of wireless light communication.