Research Projects

Massive multi-input multi-output (MIMO), a technology developed by Marzetta in 2010, has become a practical technology in 5G standards. However, 5G's cell-centric architecture limits performance due to interference from neighboring cell users. To address this, cell-free massive MIMO and reconfigurable intelligent surfaces (RIS) and non-orthogonal multiple access (NOMA) are considered technologies for beyond 5G communication. RIS is composed of passive elements that can be tuned to provide phase-shift, reducing network energy consumption. NOMA serves multiple users on the same orthogonal time/frequency resource, allowing a large number of users, such as IoT devices, to be connected to the network. This work investigates the RIS-assisted cell-free massive MIMO NOMA system, aiming to enhance reliability, connectivity, throughput, and energy efficiency. The project aims to investigate practical constraints such as spatial correlation, hardware impairments, and spectral efficiency bounds. Information theory-based spectral efficiency bounds will be derived, and energy efficiency (EE) will be the focus of next-generation wireless technology. Energy-efficient and spectral-efficient algorithms will be designed, and a cell-free testbed will be developed using software-defined radios to showcase the advantage of using distributed antennas instead of collocated antennas.