A Unified Modulation Framework in Doubly Selective Channels by Exploring Fast Unitary Transformations

As various modulation techniques have being proposed to meet the practical demands of high-mobility communications, this paper introduces a unified modulation framework based on fast unitary transformations, drawing inspiration from the use of diversity to combat selective fading. We show that several classic modulation schemes arise as special cases of the proposed framework and devise a unified implementation architecture. The unified framework enables us to leverage the unique characteristics of each domain to optimize system performance and streamline the signal processing workflow. Finally, we explore how the proposed unified modulation can be integrated with some key technologies in 6G, paving the way for the evolution of future communication networks.