Analysis of 3D positioning error for multipath indoor VLC system

A comparative analysis of 3D positioning error for two different configurations using different layouts of visible light communication (VLC) systems is presented in this paper. The Received Signal Strength (RSS) has been implemented for indoor localization systems using Line-of-Sight (LoS) and diffused reflection signals. The room size for configuration-1 is 5 m × 5 m × 3 m, and the distance between adjacent LEDs is 2.5 m, 2.00 m, and 1.5 m for cases-1, case-2, and case-3, respectively, whereas the room size for configuration-2 is 7 m × 7 m × 5 m, and the separation between the LEDs is 3.5 m, 3 m, and 2.5 m for their respective cases. Through investigation, it has been shown that when only LS signal is considered, the separation between LEDs may not be an issue because positioning error changes by a very small amount as the separation between LEDs changes. The results show that as the distance between adjacent LEDs decreases, the received signal strength for LoS and L-R1 signals increases. However, positioning error and BER rise, while the bit rate falls. Furthermore, the positioning error Vs receiver plane height for all three cases in configuration-1 is the same up to a height of 2.89 m, whereas the positioning error in configuration-2 is the same up to 4.4 m for all cases. The positioning error for case-1 decreases as the height in configuration-1 exceeds 2.89 m. Similarly, after reaching a height of 4.4 m for case-2, the positioning error in configuration-2 decreases. The LoS positioning error versus semi angle ${\phi }_{1/2}$ of the LED as well as the FOV of the receiver has been simulated for different positions of the receiver in configuration-1. The investigation shows that the minimum positioning error is achieved at ${\phi }_{1/2}$ and FOV equal to 66.66⁰ for all the positions of the receiver in the room. Thus, before configuring a practical indoor VLC geometrical model, proper VLC configurations such as LED separation, FOV of the receiver, semi angle of LED, and receiver height should be chosen based on the room dimensions.