Antenna Deployment of 5G Ultra High-Density Distributed Massive MIMO by Low-SHF-Band Indoor and Outdoor Experiments

In order to tackle rapidly increasing traffic, distributed Massive MIMO (DM-MIMO) has been proposed for fifth-generation (5G) mobile communication systems. DM-MIMO coordinates lots of distributed transmission points (TPs) that are located in ultra-high density (UHD) and that use an appropriate number of antenna elements. Furthermore, DM-MIMO with UHD-TPs can create user-centric virtual cells corresponding to user mobility. To deploy TPs for DM-MIMO, some key parameters such as the number of the distributed TPs, the number of antenna elements for each TP, and proper distance between TPs should be determined. Conventional works have shown such key parameters for DM-MIMO with UHD-TPs by computer simulations. However, these parameters have not been evaluated in actual deployment environments. We measure low-SHF- band (4.5 GHz) radio propagation channel in indoor and outdoor experiments of DM-MIMO with UHD-TPs. Then, by exploiting the experimental results, the appropriate numbers of antenna elements based on maximum system throughput criterion are shown for 5G DM-MIMO by computer simulations.