Indoor optical wireless communication system with continuous and simultaneous positioning

The optical wireless communication (OWC) technology has been widely studied to provide high-speed communications in indoor environments. The indoor OWC-based positioning function is also highly demanded and the received signal strength (RSS) method has attracted intensive interests, where multiple transmitters are used and the positioning information is provided by estimating the channel gain from each transmitter with known location. However, this process normally requires dedicated positioning time slots, RF carriers or codewords, which limit the system data rate and throughput. To solve this limitation, in this paper we propose a filter-enhanced indoor OWC positioning scheme, where spatial waveform shaping filters are applied to the transmitters, thus enabling the signals from different transmitters to be separated via matched filters at the receiver side. Hence, this approach allows the RSS information to be obtained from the wireless communication signal directly and the positioning function realized without affecting the wireless communication data rate or throughput. In addition, since positioning is realized using the communication signal, continuous positioning can be achieved for real-time tracking. The proposed filter-enhanced positioning scheme is experimentally demonstrated in a near-infrared indoor OWC system with laser transmitters. Results show that an average positioning accuracy of 5.41 cm and 2.5 Gb/s wireless communication are achieved simultaneously. The proposed filter-enhanced positioning scheme can also be applied in visible light communication (VLC) systems with LED transmitters, and the feasibility is verified via simulations. The proposed filter-enhanced scheme provides a promising positioning method in indoor OWC systems without affecting the wireless data communication.