US Patent 7133617 Reflection detection in an optical wireless link

In an optical wireless network, where light beams are transmitted over-the-air, reflections of the transmitted light beams may cause a receiver of an optical wireless device to detect and subsequently lock onto the signal that it transmitted. By doing so, the network is effectively broken. A method and apparatus to detect the reception of reflected signals using minimal additional hardware and data is presented. Should a reflected signal be detected, the receiver is prevented from locking onto the signal, allowing the receiver to detect and subsequently lock onto light beams originating from other optical wireless devices.