28 GHz Distributed-MIMO Comprehensive Antenna Calibration for 5G Indoor Spatial Division Multiplex

This paper describes the experimental verifications of a 28 GHz multi-user distributed multiple-input multiple-output (MIMO) using newly developed comprehensive calibration without additional transceiver path for 5G indoor multiple access applications. The eight distributed active antennas are connected to a digital and mixed signal processing unit. The proposed calibration method for the distributed MIMO enhances the number of simultaneous users and system throughput. We demonstrate the zero-forcing spatial multiplex using up-link to down-link channel reciprocity for two, four, and six user equipment in actual office over the air circumstances. The distributed MIMO exhibits two times greater spatial multiplexing efficiency than a conventional collocated Massive MIMO and achieves the system throughput of 2.1 Gbps per 100 MHz summing simultaneous connected six users.