Joint optimization for 6G beyond diagonal IRS-assisted multi-carrier NOMA vehicle-to-infrastructure communication

Joint optimization for 6G beyond diagonal IRS-assisted multi-carrier NOMA vehicle-to-infrastructure communication

연구 분야: Networking

학회: The Journal of Supercomputing

The intelligent reconfigurable surface (IRS) is regarded as a highly promising technology for facilitating and enhancing the performance of future wireless communication networks. This is due to its capacity to effectively modify wireless channels in desired destinations with low-cost design and energy consumption. A significant amount of research has been dedicated to exploring the use of conventional IRS, where each phase response element is only connected to its own ground load with no connection to the other phase response elements. However, the simple design of conventional IRS limits its capacity to adjust passive beamforming. This study focuses on the implementation of beyond diagonal IRS (BD-IRS) in multi-carrier non-orthogonal multiple access (NOMA) vehicular communication, surpassing the use of diagonal phase shift matrices. Specifically, we propose a new optimization approach that aims to maximize the achievable spectral efficiency of a multi-carrier NOMA vehicular communication with BD-IRS assistance. This is achieved by optimizing the transmission power of RSU and the phase response of the BD-IRS. We utilize block coordinate descent and successive convex approximation methods to convert the original optimization problem into a series of subproblems. For the power allocation problem at RSU, we adopt Dinkelbach’s and first-order Tayler approximation while exploiting unitary constraint transformation for the phase response problem at BD-IRS and then use the CVX toolbox for the solution. The numerical findings clearly illustrate the advantages of the proposed optimization framework and implementing BD-IRS in multi-carrier NOMA vehicular communications networks in comparison to the conventional IRS architecture.