Scalable optical relay for LED-ID systems

LED-ID (light emitting diode - identification) system typically uses line of sight (LOS) channels to achieve high data rate and bright illumination. In LOS channel, however, the LED-ID system has very narrow coverage. In cellular networks, the relay station has been introduced to improve system throughput and coverage. Accordingly, new optical relay scheme is essential to support multi-hop transmission in relay-assisted LED-ID networks. In this paper, effects of shadow region problem are investigated for LED identification (LED-ID) system in a non-line of sight (NLOS) environment. A scenario on shadow region problem is proposed, and nominal interrogation range of a desired reader is derived from this model. In order to expand the coverage of LED-ID networks, an efficient optical relay scheme is proposed and simulated by employing cooperative communication methodology. It is confirmed that the proposed technique performs well both in terms of throughput and fairness by simulation results. Also, the proposed scheme is very effective to expand coverage of LED-ID communication networks.