The applications for this are wide-ranging in both commercial and residential settings, and the US Patent (number 6,548,967) covers local area networking through a lighting system that uses LEDs both to generate light and to wirelessly communicate data to external devices such as pagers, personal digital assistants, and any other device that's connected to the network. For example, an LED-based lighting system in an office could transmit data that triggers security systems to engage at a scheduled time; the lighting in a hospital could activate doctors' pagers in the event of an emergency; and the lighting in a residence might communicate to the owner's PDA that doors are locked or unlocked.
(Ruth Rossington)
