Junho Hwang

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In this paper, we propose an indoor positioning system in which the visible light radiated from LEDs is used to locate the position of receiver. Compared to current indoor positioning systems using LED light, our system has the advantages of simple implementation, low cost and high accuracy. In our system, a single photo diode (PD) receives pilot signals(More)
VLC system transmits data by controlling LED and receives data through photo diode, which is considered as one of strong candidates of next generation wireless communication systems. Especially, VLC shows a better performance than the existing indoor positioning technology using WPAN as it can measure in the unit of cm to mm. In this paper, we proposed an(More)
Visible light communication moves to the advanced research period for developing application services, but most of applications are limited only to PtP service model. However, PtMP communication environment for VLC is required to accommodate more various applications. In this paper, we analyze an effect of key parameters on network performance in the star(More)
Ethernet passive optical network (EPON) becomes a key technology for the next generation broadband access networks due to its cost-effectiveness and high data rate. One of the research issues in EPON is to support service differentiation and fairness. For service differentiation, the conventional limited algorithm is extended with strict priority queuing(More)
Visible light communication (VLC) is expected to be the next generation of indoor wireless communication. A VLC system uses many LED chips, and its performance is greatly affected by the direction of light-emitting diodes (LEDs). Normally, the LEDs are directed vertically downward to the floor. In this paper, we introduce an LED layout scheme in which the(More)
Wireless mesh network (WMN) has drawn much attention as a cost-effective way of providing wireless Internet service in wide area. The optimization problems have been an issue in wireless mesh network. In the previous studies, optimal locations of gateways are determined so that deployment cost is minimized while satisfying the required network performance.(More)
Visible light communication (VLC) is expected to be the next generation of indoor wireless communication. Commonly, a VLC system uses many LED chips, and its performance is affected a lot by the placement of LEDs. In this paper, we propose LED panel model that can place LEDs with some angle. Based on the simulation results, the effect of changing LED(More)