In the visible light (VL) communication based on the multicolor channel between colored LEDs and photodiode, a uniform performance on color channel may be desired, and VL communication services using multiple color channels should be attained by only one VL receiver. However it has been known that the received signal has the severe color distortion by the receiver performance variation on multicolor channels since photodiode produce more electrical current on red color than on green or blue color channel. In this paper we estimate the compensation extent of the color distortion in advance by color map and utilize the optimal VL transceiver circuit for distortion-less VL communication in the multicolor VL channel. We can see that the conventional technique without any compensation function of color distortion effect meets a failure in the color VL communication trial because of the different VL communication distance on each color VL channel, but the proposed scheme has no distortion due to the performance variation of each color VL channel in the overall range of communication distance.
The conventional visible light (VL) communication signals based on the LED array and photodiode severely decreases at the far away receiving point in the VL channel by the path loss effect and the insufficient compensation capability of the receiver, which results in failure of long-range VL communication for smart indoor service. In this paper, we consider the long-range VL communication technique that the compensation extent of the path loss distortion provides in advance by threshold map, and utilizes the optimal transceiver circuit for long-range VL communication. And so we can see that the proposed long-range VL communication technique overcomes the path loss problem through the compensation effect from utilizing the optimal threshold voltages into VL receiver, and attains the success of longrange VL communication test in the overall range from zero to 1070 cm distance.
Indoor visible light (VL) positioning systems for smart indoor services are negatively affected by both cochannel interference from adjacent light sources and VL reception position irregularity in the three-dimensional (3-D) VL channel. A secure positioning methodology based on a two-dimensional (2-D) encrypted VL map is proposed, implemented in prototypes of the specific positioning system, and analyzed based on performance tests. The proposed positioning technique enhances the positioning performance by more than 21.7% compared to the conventional method in real VL positioning tests. Further, the pseudonoise code is found to be the optimal encryption key for secure VL positioning for this smart indoor service.
The conventional visible light (VL) communication signals based on the LED array and photodiode severely decreases at the far away receiving point in the VL channel by the path loss effect and the insufficient compensation capability of the receiver. In this paper, we consider the wide-range VL communication technique that the compensation extent of the path loss distortion provides in advance by threshold map, and the optimal receiver circuit with compensation utilizes for VL communication.
For overcoming the performance degradation problems of the conventional visible light (VL) positioning system, which are due to the co-channel interference by adjacent light and the irregularity of the VL reception position in the three dimensional (3-D) VL channel, the secure positioning technique based on the two dimensional (2-D) encrypted VL map is proposed, implemented as the prototype for the specific embedded positioning system, and verified by performance tests in this paper. It is shown from the test results that the proposed technique achieves the performance enhancement over 21.7% value better than the conventional one in the real positioning environment, and the well known PN code is the optimal stream encryption key for the good VL positioning.
A simple, accurate, secure, long-lasting, and portable hybrid positioning system is proposed and designed in this paper. It
consists of a lighting LED that generates visible light data corresponding to position information of a target and a Zigbee
wireless network communication module with low power, security, and service area expansion characteristics. Under an
indoor environment where there is 23.62m distance between an observer and the target, the presented hybrid positioning
system is tested and is verified with the functions of Zigbee three hop wireless networking and visible light
communication (VLC) scheme. The test results are analyzed and discussed.
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