Se-Hoon Yang

An Indoor Visible Light Communication Positioning System Using a RF Carrier Allocation Technique

We propose a new indoor positioning system utilizing visible light communication. Intensity modulation/direct detection and carrier allocation methods are utilized in the proposed system. Simultaneous three channel transmissions were applied to calculate the receivers position. The characteristics of the proposed positioning system were investigated through simulation based on the experimental results, and the feasibility of the proposed system was verified by experimentation. The experimental result shows that the average error of estimated positions is reduced to 2.4 cm using adjustment process by normalizing method, which is compared with 141.1 cm without adjustment process.

Three-Dimensional Visible Light Indoor Localization Using AOA and RSS With Multiple Optical Receivers

A novel concept is proposed for integrating optical wireless visible light communications with 3-D indoor positioning using a single transmitter and multiple tilted optical receivers. We modeled a channel link, which was based on the transmitter and receiver characteristic data obtained in this experiment. The proposed 3-D positioning algorithm is based on gain difference, which is a function of the angle of arrival and the received signal strength. Our demonstration shows that the proposed algorithm can determine accurate positions, including height, without intercell interference.

Indoor Location Estimation Based on LED Visible Light Communication Using Multiple Optical Receivers

An novel concept for integrating visible light produced by LEDs with indoor positioning using multiple optical receivers is presented in this study. We propose an algorithm using the received signal strength indication (RSSI), which changes by on transmission distance and angle. In order to estimate the position, the transmitters location code was received using multiple optical receivers. The validity of the proposed scheme was demonstrated by determining the local position using distances between the transmitter and receivers, and the relative position between receivers.

Outdoor Visible Light Communication for inter- vehicle communication using Controller Area Network

In this paper, we implemented the outdoor Visible Light Communication (VLC) system based on Controller Area Network (CAN) which is normally used in a car, plane, ship, product line control system, medical device and industrial device. For vehicle to vehicle (V2V) or indoor vehicle communication, we used common use device such as head light and back light. We made an application circuit and explained the principle. Also, we found an outdoor VLC problem which is sun light noise and photo detector (PD) saturation problem. Circuits pulse features were demonstrated by signal. Total communication distance was 20 m in the daytime outdoor condition and its experimental transmission performance is presented.

Mitigation of Inter-Cell Interference Utilizing Carrier Allocation in Visible Light Communication System

It is necessary in visible light communication where different information from adjacent cells is distinguishable without inter-cell interference for indoor localization-based services and positioning systems. In order to mitigate inter-cell interference, a carrier allocation-visible light communication system, adopting various carriers among the systems respective cells, is suggested. The effects of inter-cell interference for a single channel and the proposed systems are investigated by experimentation with simultaneous transmissions of QPSK signals.

Channel Assignment Technique for RF Frequency Reuse in CA-VLC-Based Accurate Optical Indoor Localization

We propose a novel method of frequency assignment for the purpose of efficient RF frequency reuse in an indoor positioning system based on carrier allocation visible light communication. We investigate the performance characteristics of hexagonal, square, and rectangular cell layouts. We experimentally demonstrate a real-time indoor positioning system and make analytical comparisons between different cell layouts to determine the optimum frequency assignment for LED-based coverage.

Inter-cell interference mitigation and indoor positioning system based on carrier allocation visible light communication

A visible light communication system including various signal types transmitted among the systems respective cells needs to be considered as a viable option for indoor localization-based services and positioning systems. In order to mitigate inter-cell interference, a carrier allocation-visible light communication system (CA-VLC), adopting various carriers among the systems respective cells, is suggested. The effects of inter-cell interference for a single channel and the proposed systems are investigated by experimentation with simultaneous transmissions of QPSK signals. Finally, the positioning system based on the CA-VLC is implemented by experimentation with theoretical analysis.

Optimized pre-equalization for gigabit polarization division multiplexed visible light communication

Abstract. We experimentally demonstrated a gigabit visible light communication system employing polarization division multiplexing and adaptive modulation optical-discrete multitones by using a phosphor-based white light-emitting diode. An optimized pre-equalization circuit was used to prevent clipping of the baseband signal, which exceeded the linear operating range of the LED, and to control the power distribution of each subcarrier in order to obtain an efficient bit-loading profile. Using this technique, we achieved 1.025 and 1.016 Gbps transmissions for each polarization channel and a total of 2.041 Gbps transmissions were experimentally verified. In each transmission, bit error rate performances were below the forward error correction limit.

Indoor positioning system based on visible light using location code

In this paper, location estimation algorithm was researched for location based service. In order to mitigate interference, location code was sent by using time division multiplexing. Surface equation can be made by using signal feature distribution. We present experimental results that demonstrate the feasibility of proposed system to estimate local position with a high accuracy.

Indoor positioning system based on carrier allocation visible light communication

The indoor optical positioning system utilizing visible light communication with the modulation method of carrier allocation is proposed. Trilateration method is adopted for determining an estimated position. Even though an inaccurate estimation of distance between transmitter and receiver is caused due to the radiation pattern of LED and incidence angle to receiver, an accuracy of 6-cm positioning error is experimentally achieved using normalization method.