Group layer MU-MIMO for 5G wireless systems

Multiple-input multiple-output (MIMO) and nonorthogonal multiple access technologies are considered as fundamental components to meet the high spectral efficiency requirements of the forthcoming 5G wireless systems and beyond. In this context, group layer multiuser MIMO (GL-MU-MIMO) scheme has been proposed by the authors with linear group multiuser detection and receive antenna selection (RAS) to increase the number of simultaneously and reliably connected users more than the utilized number of radio frequency chains at the base station. In this paper, we derive the sum rate and capacity region expressions for GL-MU-MIMO uplink Rayleigh fading channels to demonstrate the impact of power allocation on the system performance and user-fairness. In addition, two low complexity RAS algorithms are proposed to maximize the sum rate of designed users' groups and overall channel capacity. These techniques are utilized for new dynamic user grouping, RAS, and power allocation strategy to optimize the system performance under total received power and minimum user rate constrains. Compared with the generic MU-MIMO, numerical simulations demonstrate valuable tradeoffs between user overloading, complexity, and achieved performance through efficient utilization of groups' power allocation. The new outcomes of GL-MU-MIMO extends the state-of-the-art towards diverse multi-antenna applications for future communications.