Efficient n-M-PAWM hybrid modulation scheme for high data transmission in visible light communication system

Abstract

Visible-Light Communications (VLC) is a new wireless communication technology, which has attracted particular attention as a promising solution for very high speed 5G, and 6G wireless networks in indoor environments. Intensity modulation (IM) is considered as the most appropriate modulation technique for VLC. This paper proposes to study a visible light communication (VLC) system with intensity modulation and direct detection (IM/DD). A channel modulation scheme is designed and encoded either in L-level pulse amplitude modulation (PAM), pulse position modulation (PPM), or pulse width modulation (PWM). In order to improve transmission efficiency, Hybrid Pulse Amplitude Position Modulation (PAPM) and Pulse Position Width Modulation (PPWM) are proposed in optical wireless communication (OWC), especially in VLC technologies. In this Paper, we propose a novel combination between PAM and PWM modulation schemes, called Pulse Amplitude Width Modulation (PAWM). The proposed modulation decreases the bit error ratio (BER) of VLC system, approximately 10−8 at Signal Noise Ratio (SNR) equal 12dB, and increases the system's transmission data rate to 210.8Mb/s at BER 10−7 for 2−4−PAWM. The normalized power and bandwidth requirements will be developed. The results show, from number M=32pulses per symbol, the transmission information rate ratio (IRR) is increased to3,75. Furthermore, a study of the Peak-to-Average Power Ratio (PAPR) for various hybrid modulations is conducted. Finally, the analytical expressions for power requirements and bandwidth, PAPR, and IRR expression of the proposed modulation scheme are investigated. The results show that the proposed hybrid modulation scheme could lower the BER and increase the data rate, and demonstrates the high potential implementation for VLC technology.