Waveform Coexistence-Driven RSMA: A Pioneering Strategy for Future 6G Networks

Two critical approaches have emerged in the literature for the successful realization of 6G wireless networks: the coexistence of multiple waveforms and the adoption of non-orthogonal multiple access. These strategies hold transformative potential for addressing the limitations of current systems and enabling the robust and scalable design of next-generation wireless networks. This paper presents a novel rate splitting multiple access (RSMA) framework that leverages the coexistence of affine frequency division multiplexing (AFDM) and orthogonal frequency division multiplexing (OFDM). By transmitting common data via AFDM at higher power in the affine domain and private data via OFDM at lower power in the frequency domain, the proposed framework eliminates the reliance on successive interference cancellation (SIC), significantly simplifying receiver design. Furthermore, two data mapping approaches are proposed: a clean pilot method, where pilots are allocated without any data overlapping, ensuring clear separation, and an embedded pilot method, where pilots overlap with data for more efficient resource utilization. Channel estimation is then performed for different channel types. Simulation results demonstrate the robustness and efficiency of the proposed approach, achieving superior performance in efficiency, reliability, and adaptability under diverse channel conditions. This framework transforms non-orthogonal multi-access design, paving the way for scalable and efficient solutions in 6G networks.

Single-Carrier Waveform Design for Joint Sensing and Communication

The emergence of 6G wireless networks demands solutions that seamlessly integrate communication and sensing. This letter proposes a novel waveform design for joint sensing and communication (JSAC) systems, combining single-carrier interleaved frequency division multiplexing (SC-IFDM), a 5G communication candidate signal, with frequency modulated continuous wave (FMCW), widely used for sensing. The proposed waveform leverages the sparse nature of FMCW within SC-IFDM to achieve orthogonal integration in three steps: SC-IFDM symbols are allocated alongside the sparse FMCW, followed by the SC-IFDM transform into the time domain, and a cyclic prefix (CP) is applied in which phase shifts are introduced to the FMCW. Additionally, an enhanced channel estimation method is incorporated to boost system performance. Simulation results demonstrate the proposed waveform's ability to deliver high-resolution sensing and superior communication performance, surpassing traditional multicarrier designs.

Redefining Orthogonal Co-Existence: A Mother Waveform Framework for DFT-Based Waveforms

In this paper, we introduce the concept of a mother waveform to address key challenges in 5th generation (5G) and 6th generation (6G) networks, including spectral efficiency, backward compatibility, enhanced flexibility, and the integration of joint sensing and communication (JSAC). We propose single-carrier interleaved frequency division multiplexing (SC-IFDM) as the mother waveform and demonstrate, through rigorous mathematical modeling, that it can generate all discrete Fourier transform (DFT)-based waveforms without requiring structural modifications. Specifically, by selectively configuring lattice indices and phase adjustments, SC-IFDM enables seamless adaptation to diverse waveforms, such as orthogonal frequency division multiplexing (OFDM), orthogonal chirp division multiplexing (OCDM), orthogonal time-frequency space (OTFS), affine frequency division multiplexing (AFDM), and frequency-modulated continuous wave (FMCW) within a unified framework. Critical aspects such as coexistence strategies and resource allocation are thoroughly explored. Simulation results demonstrate the proposed frameworks ability to deliver superior communication performance, robust sensing capabilities, and efficient coexistence, surpassing traditional waveform designs in scalability and adaptability.