Design and spectral analysis of mixed-carrier communication for sixth-generation networks

The fifth-generation (5G) wireless cellular network is expected to be ready for commercialization within this year. The huge spectrum enabled by the millimetre-wave (mm-Wave) technology is expected to introduce a hype in data usage per user. The 5G is also expected to concurrently support a wide variety of services; however, the practical trade-offs associated with concurrent services require further investigations. In this work, a physical layer (PHY) design to support visible light communications is considered to efficiently support concurrent services that are essential to serve the needs of the sixth-generation (6G) network. A novel communication technique, i.e. mixed-carrier communication (MCC), is proposed. MCC enables simultaneous wireless services such as broadband access, low-rate internet-of-things connectivity, device-free sensing, and device-based localization. This study presents, firstly, a thorough investigation of the design procedure of the novel MCC PHY, secondly, the spectral profile of MCC towards proper spectrum management and interference analysis, and thirdly, performance evaluation based on modelling, simulation and an experimental proof-of-concept. The design steps recommend that the system performance degrades beyond a signal-to-noise ratio (SNR) threshold. For instance, SNR of 25.1 dB and 2.6652 optical power ratio between the communications signal and the driving envelope, for 64-quadrature amplitude modulation (64-QAM), are recommended to avoid performance degradation due to clipping. Simulation results show an interference-immune performance of a properly managed spectrum. For a bit-error-rate (BER) of 10^-3, an SNR penalty of 2-5 dB is observed for different interference scenarios. The experimental measurements illustrate a high-quality signal of 21 dB SNR at 50 cm and 10^-3 BER using 64-QAM.