Wireless Internet access via light bulbs

Professor Chi Nan of Shanghai's Fudan University has used a LED bulb to provide a high speed internet connection

Professor Nan explained that by using Li-Fi technology a light bulb with embedded microchips can produce data rates as fast as 150Mbps, much higher than the average broadband connection in China.

Wherever there is an LED light bulb, there is an Internet signal,. Turn off the light and there is no signal.
— Professor Chi Nan

The term Li-Fi was coined by Harald Haas from the University of Edinburgh in the UK and refers to a type of visible light communication technology that delivers a networked, mobile, high-speed communication solution in a similar manner as WiFi.

Xinhua News article - http://news.xinhuanet.com/english/china/2013-10/17/c_132806591.htm

The problem with Li-Fi technology is getting the Internet to the bulb. It is understood all current Li-Fi systems make use of polluting Power Line Telecommunications (PLT) which can render the HF radio spectrum unusable.

UKQRM are a group that fights PLT interference - http://www.ukqrm.org.uk/