Efficient clustering for NOMA with THz mMIMO D2D inspired 6G system model

Terahertz (THz) communication, offering unprecedented bandwidth, is a key enabler for the high data rates envisioned in 6G wireless networks. To further enhance capacity and spectral efficiency, this paper proposes a novel 6G hybrid system model integrating THz communication with massive multiple-input multiple-output (mMIMO), cooperative non-orthogonal multiple access (NOMA), and device-to-device (D2D) communication within a heterogeneous network architecture comprising macrocells and small cells. This integrated approach aims to address the escalating demand for connectivity. A crucial aspect of our proposed system is the development of an Antenna Angle Bound (AAB) clustering technique. This innovative method leverages antenna parameters, specifically beam angle, and width, to intelligently group users. By forming clusters based on these spatial characteristics, the AAB technique minimizes inter-user interference, a critical challenge in mMIMO systems. This interference reduction directly contributes to significantly improving the overall system sum rate. Furthermore, we formulate an energy efficiency maximization problem to optimize power allocation coefficients across the various technologies employed. This optimization ensures a balance between achieving high data rates and minimizing energy consumption, a critical consideration for sustainable 6G deployments. The complex optimization problem is tackled using the alternating direction method of multipliers algorithm, which efficiently decomposes the problem into manageable sub-problems. The combination of THz communication, mMIMO, cooperative NOMA, D2D, the AAB clustering technique, and the optimized power allocation promises to deliver a substantial leap in performance for future 6G wireless communication systems, addressing the growing need for higher data rates and improved energy efficiency. The simulation shows that the proposed 6G hybrid system schemes perform better than the traditional models by attaining a 561.5% improved sum rate, 11.3% more power saving, and 533.3% enhancement in energy efficiency.