Design of a Li-Fi Based Indoor Data Transmission System for Office Environments in Abuja

This project designs and demonstrates a Li-Fi based indoor data transmission system for office environments in Abuja, Federal Capital Territory, exploiting visible light communication to provide high-speed wireless data connectivity as a complement to conventional Wi-Fi networks. Li-Fi offers potential advantages in security, electromagnetic interference immunity, and spectrum availability that are relevant to government and corporate office environments where wireless network security and reliable connectivity are priorities. The system consists of a transmitter unit employing a high-brightness LED driver circuit modulated at rates up to 1MHz by a UART data signal from a PC, and a receiver unit incorporating a photodiode preamplifier and signal conditioning circuit connected to a second PC. A custom communication protocol handles data framing, error detection, and retransmission requests. Bit error rate testing was conducted across transmission distances of 0.5m to 5m and under varying ambient light interference conditions including fluorescent and natural light environments. At 1m distance with the transmitter directly overhead, the system achieved a data rate of 500 kbps with a bit error rate below 10 to the power of negative 5. Performance degraded at oblique angles beyond 30 degrees from the vertical, indicating the need for multiple LED transmitters per room for complete coverage. The prototype successfully transmitted text files and audio streams in real time. Recommendations include upgrading the modulation scheme to OFDM to increase throughput and designing a ceiling-mounted multi-LED array for uniform coverage. Keywords: Li-Fi, visible light communication, indoor wireless, LED modulation, Abuja.