Optimum power allocation for uniform illuminance in indoor visible light communication

In this paper an optimal power allocation scheme is proposed to acheive uniform illuminance. Regular arrays and random geometries are considered for an arrangement of the source LEDs. Uniform illuminance is accomplished by considering the variance of the received power on the receiver plane as metric and framing it as a convex optimization problem. Numerical results show that the quality factor of random geometries are superior to fixed geometries. While preserving uniformity, the cost of the system can be reduced when random geometries are used. © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

A study of visible light communication channels for high speed roadways

A visible light communication channel study is conducted for high speed roadways under clear night sky conditions in which street light poles transmit to receivers on top of moving vehicles. A detailed analysis of the communication channel is undertaken. Exact and approximate analytical DC channel responses are obtained and analyzed, and the channel capacity and RMS time delay spreads are derived. Numerical studies verify that visible light communications are feasible for high speed roadways

The movement-rotation (MR) correlation function and coherence distance of VLC channels

Adaptive transmission based on instantaneous channel state information is an important methodology to improve data rates of mobile users, which requires the periodic update of channel variations. Different from radio frequency (RF) channels, whose variations are governed by Doppler and multi-path effects, visible light communication (VLC) channel variations are mainly related to receiver movements and rotations. In this article, a movement-rotation (MR) correlation function is proposed to measure VLC channel variations with the changes in receiver location and orientation. The correlation function of VLC channel gain in the time domain can then be approximated by the MR correlation function, which is an important criterion for the design of data transmission frames. It is verified that the approximation by MR correlation function can approach the actual simulation and experiment results of VLC channel gain correlation function in the time domain. In addition, experiment and simulation results are presented to investigate variation characteristics of VLC channels in different scenarios. It is shown that a receiver movement of several decimeters or a change of 10-20 degrees in the inclined angle of the receiver is required in a typical scenario in order to observe a distinguishable change of VLC channel gain

Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm

Abstract— Online transportation has become a basic requirement of the general public in support of all activities to go to work, school or vacation to the sights. Public transportation services compete to provide the best service so that consumers feel comfortable using the services offered, so that all activities are noticed, one of them is the search for the shortest route in picking the buyer or delivering to the destination. Node Combination method can minimize memory usage and this methode is more optimal when compared to A* and Ant Colony in the shortest route search like Dijkstra algorithm, but can’t store the history node that has been passed. Therefore, using node combination algorithm is very good in searching the shortest distance is not the shortest route. This paper is structured to modify the node combination algorithm to solve the problem of finding the shortest route at the dynamic location obtained from the transport fleet by displaying the nodes that have the shortest distance and will be implemented in the geographic information system in the form of map to facilitate the use of the system. Keywords— Shortest Path, Algorithm Dijkstra, Node Combination, Dynamic Location (key words