Visible light for communication, indoor positioning, and dimmable illumination: A system design based on overlapping pulse position modulation

Abstract

In this paper, we design a dimming compatible visible light communication (VLC) system with asynchronous and optimum indoor positioning method in a standard office room in combination with asynchronous and optimum indoor positioning method according to illumination standards under channel constraints. We use overlapping pulse position modulation (OPPM) to support dimming control by changing the code weights. The system parameters such as a valid interval for dimming together with an upper bound for bit rate according to the channel delay spread are investigated. Moreover, considering the dispersive VLC channel and using Monte Carlo (MC) simulations, a method is proposed to determine the minimum code length in different dimming levels in order to achieve a valid bit error rate (BER). Then, the trellis coded modulation (TCM) is suggested to be applied to OPPM in order to take advantage of consequent coding gain which could be up to 3 dB. Finally, in order to enable asynchronously and with high throughput data transmission of LEDs for the purpose of indoor positioning, we propose using one-persistent carrier sense multiple access (CSMA) network protocol. Using received signal strength (RSS) based trilateration, the two dimensional positioning error of around 10cm is verified by the simulation results.