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5G K-SimSys is a system-level simulator which has been designed and implemented to provide an open platform and flexible testbed for evaluating the system-level performance of 5G standard. In this paper, we present its design overview with the overall modular structure, including the functionality of the flexible modules. Meanwhile, massive multi-input multi-output (MIMO) is a key technology for improving the spectral efficiency in 5G systems. Because massive MIMO has been standardized in 3GPP Rel-13 (LTE-Advanced Pro), the next generation of massive MIMO standard is now available in Rel-16, a.k.a New Radio (NR) interface, for further improvement of the average spectral efficiency with more antenna elements, over the higher frequency band. In particular, the beam-based air interface for above 6 GHz band involves various antenna configurations and feedback schemes, requiring a more complex testbed for system-level performance evaluation. This paper examines the multi-antenna technologies in 3GPP NR specification to develop its system-level model in 5G K-SimSys in order to test the factors affecting performance in the corresponding environments through various embodiments. In the simulation results, the baseline performance for massive MIMO in NR is evaluated as varying the number of antenna ports and the number of spatial multiplexing layers in various experimental environments. Particularly, the effect of vertical beamforming on interference is evaluated for the full dimension MIMO (FD-MIMO). In order to demonstrate that 5G K-SimSys is an easy-to-design simulators that can facilitate modification and reconfiguration owing to its modularized and customized structure, we consider the proposed bandwise analog beamforming (BAB) scheme. Its modular and flexible structure immediately allows for implementing the virtual modules for bandwise analog beamforming by reusing the elementary modules as hierarchically designed simulator objects.

The 3GPP standardized the physical layer specification in 5G New Radio to support enhanced mobile broadband (eMBB) and ultra-reliable low-latency communication (URLLC) coexistence in usage scenarios including aerial vehicles (AVs). Dynamic multiplexing of URLLC traffic was standardized to increase the outage capacity. DM allocates a fully overlapped bandwidth part (BWP) of eMBB and URLLC AVs to perform the immediate scheduling of URLLC traffic by puncturing ongoing eMBB traffic. However, DM often suffers from a significant frame error incurred by puncturing. Meanwhile, BWP can be sliced orthogonally for eMBB and URLLC AVs, possibly preventing overdimensioning the resources depending on the eMBB and URLLC traffic loads. In this paper, we propose a dynamic BWP allocation scheme that switches between two multiplexing methods, dynamic multiplexing (DM) and orthogonal slicing (OS), so as to minimize an impact of uRLLC traffic on eMBB traffic. To implement efficient BWP allocation, the capacity region is analyzed by considering the effect of physical layer parameters, such as modulation and coding scheme (MCS) levels and code block group size on DM and OS. OS is effective for improving the eMBB throughput under a URLLC latency constraint for deterministic and predictable URLLC traffic, whereas DM has limited error-correcting capability against the URLLC’s puncturing effect. The relative MCS level of eMBB and URLLC is critical in determining the eMBB traffic tolerance against puncturing. Identifying the performance tradeoff between DM and OS, the tolerance level is quantified by a URLLC load threshold. It is given in an approximate closed form, which is an essential reference for selecting DM over OS, enabling dynamic BWP allocation for the URLLC AV.

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