mCore $+$: A Real-Time Design Achieving $\sim 500~\mu$ s Scheduling for 5G MU-MIMO Systems

Multi-User (MU)-MIMO technology plays a vital role in 5 G NR. Under MU-MIMO transmission, multiple users can share the same time-frequency resources simultaneously. For 5 G MU-MIMO systems, it is challenging to design a scheduler. The scheduler needs to determine resource block (RB) allocation, the number of data streams and modulation and coding scheme (MCS) for each user in each transmission time interval (TTI). In particular, multiple users can be co-scheduled on the same RB for MU-MIMO transmission. In addition, it is necessary for the scheduler to find a scheduling solution within each TTI to be useful. In this paper, we present mCore $+$ , a novel design and implementation that can achieve $\sim$ 500 $\mu$ s timing performance for 5 G MU-MIMO systems. mCore $+$ is meticulously designed with a multi-phase optimization and heavily leverages large-scale parallel computation. In each phase, mCore $+$ either decomposes the optimization problem into a number of independent sub-problems, or reduces the search space into a smaller but most promising subspace, or both. mCore $+$ is validated on a commercial-off-the-shelf GPU platform. Experimental results show that mCore $+$ can offer a scheduling solution in $\sim$ 500 $\mu$ s for up to 100 RBs, 100 users, 29 MCS levels and $4 \times 12$ MIMO systems. Also, mCore $+$ can achieve better or comparable throughput performance compared to other state-of-the-art algorithms.