With the rapid growth in the number of smart devices and sensors, the internet of things (IoT) is driving the intelligent transformation of our living spaces. Two of the fundamental requirements for providing any intelligent service inside a smart building are connectivity and localization. However, existing radio frequency-based technologies are neither bandwidth-sufficient nor accurate enough to meet the ever-increasing demand of connectivity and location intelligence, respectively. Therefore, in this thesis, visible light communication (VLC), or Li-Fi is proposed as a solution to this two-fold problem. VLC utilizes the ubiquity of optical devices, which include lighting, signage, and displays, inside a smart building to provide connectivity and location intelligence. In the proposed...[ Read more ]

With the rapid growth in the number of smart devices and sensors, the internet of things (IoT) is driving the intelligent transformation of our living spaces. Two of the fundamental requirements for providing any intelligent service inside a smart building are connectivity and localization. However, existing radio frequency-based technologies are neither bandwidth-sufficient nor accurate enough to meet the ever-increasing demand of connectivity and location intelligence, respectively. Therefore, in this thesis, visible light communication (VLC), or Li-Fi is proposed as a solution to this two-fold problem. VLC utilizes the ubiquity of optical devices, which include lighting, signage, and displays, inside a smart building to provide connectivity and location intelligence. In the proposed system, location-based information is broadcasted using optical devices that can be captured by the CMOS image sensor of a smartphone or a robot using optical camera communication (OCC). The OCC-based Li-Fi link is combined with Bluetooth and a cloud-based data collection, processing, and management system to provide location-based services. The design and implementation of the system is divided into three parts.

In the first part, a universal VLC modulator design is presented that can enable VLC in a wide variety of LED lighting, signage, and displays. The modulator can support a wide input voltage and power range and features a Bluetooth-based wireless control and iBeacon-based proximity sensing to support IoT connectivity and location-based geofencing. Experiments are conducted to verify the modulation function and its impact on the light intensity and reliability.

In the second part, a VLC receiver is implemented using a CMOS image sensor-based rolling shutter camera on a smartphone. The VLC signal is extracted and decoded from the captured images of the light using image processing techniques. The impact of various system parameters including light size, shape, color and smartphone camera hardware, on receiver’s sensitivity and detection range is studied. Based on the analysis, practical OCC receiver design guidelines are established.

In the final part, a VLC- and Bluetooth-integrated smart lighting infrastructure is used to enable high-accuracy indoor localization in large-scale venues. The high-accuracy positioning provided by VLC is complemented with a long-range non-line-of-sight Bluetooth and pedestrian dead reckoning algorithm to provide a continuous and smooth indoor positioning experience in various indoor environments with varying densities of lighting.