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We present the key concepts and design of our proposed framework for a smart supermarket (SMARTKet). We briefly introduce the infrastructure, smart functions, and enabling technologies of the SMARTKet implementation. We especially focus on the basic principles, performance evaluation in terms of localization accuracy, and proof-of-concept implementation of the indoor navigation system using visible...
This paper studies zero-forcing (ZF) precoding designs for multi-user multiple-input single-output visible light communication (VLC) broadcast channels. In such broadcast systems, the main challenging issue arises from the presence of multi-user interference (MUI) among non-coordinated users. In order to completely suppress the MUI, ZF precoding, which is originally designed for radio frequency (RF)...
This paper studies the multi-user performance of multi-cell visible light communication (VLC) systems with coordinated precoding among cells. Practically, separated LED arrays are employed to properly illuminate a large room/office. This configuration enables a multi-cell VLC system, which is analogous to that in mobile cellular networks. In such multi-cell systems supporting multiple users, the received...
Abstract-In this paper, we study multi-user multiple-input single-output (MU-MISO) visible light communications (VLC)for indoor broadcast systems. Multiple LED arrays are deployed as transmitters to serve multiple users simultaneously. In such broadcast systems, the main challenging issue is the presence of multi-user interference (MUI) among users. In order to completely cancel the MUI, the zero...
This paper studies multi-user multiple-input multiple-output (MU-MIMO) visible light communications (VLC) for indoor broadcast systems. Transmitters, configured as multiple LED arrays, and multiple users equipped with multiple photodetectors (PD) are considered. The main challenge in such broadcast systems is the multi-user interference (MUI). In order to completely suppress the MUI, the block diagonalization...
In this paper, we present a systematic experimental study of negative capacitance (NC) effect in p-i-n and p-n junctions of light-emitting devices. The focus is the dependence of NC on injected current mixed with a small ac signal (1 kHz – 13 MHz) at variable temperature in forward-biased light-emitting diode (LED) and laser diode (LD). The NC effect is shown by our measurement results to be strong...
Compared to laser diode, LED offers advantages such as lower cost, better temperature stability and longer service life. LED is therefore the preferred choice for optical communication systems when environmental conditions are uncontrolled. However, modulation rate of LED and RC-LED at 100 Mb/s and 200 Mb/s, respectively, is much lower than that of tens of Gb/s in LD and VCSEL. Our newly proposed...
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