Efficient resource allocation for rapid link recovery and visibility in visible-light local area networks

Visible-light communication provides many advantages over other forms of communications, such as visibility, high SNR (Signal to Noise Ratio), easy installation, freedom of interference from radio or electromagnetic waves, usage of license free frequency band, and high security. Furthermore, the exponentially increasing requirements and quality of LEDs (Light Emitting Diodes) have encouraged the development of visible-light communication that makes use of LEDs. In a visible-light communication system, an LOS (Line of Sight) link between two transceivers should be guaranteed due to the straightness of the visible-light signal. However, link failure caused by temporary blocking or poor orientation of a transmitter frequently occurs, causing burst frame errors. In this paper, we focus on how to let a user know about link failure as quickly as possible, in order that the link failure problem may be solved by realigning the transmission signal towards the receiver. This is furthermore a relatively straightforward matter, by the very nature of this system being a visible means of communication. It is also required that the visibility should be supported when a user attempts initial access procedure. Nevertheless, by supporting visibility, system performance can be degraded because some additional resources are required for the visibility to be enabled. In this paper, we propose three schemes for supporting visibility without reducing system performance in a visible-light local area network