Partially adaptive arrays application for MU-MIMO mode in a MmWave small cells

In this paper we provide detailed system level performance analysis of MU-MIMO mode in the millimeter wave (mmWave) small cells (Wi-Fi hotspots) environment. Traditional way of MIMO implementation assumes a single RF chain per antenna element, with all spatial processing done in the baseband. To overcome high pathloss in the mmWave bands, the large-aperture, very high gain arrays with a large number of elements (several hundreds) are required. Therefore we introduce partially adaptive arrays with reduced number of degrees of freedom which are implemented based on the modular antenna arrays (MAA) architecture. The scalable practical design of MAA allows creation of large-aperture, high-power antenna arrays with reduced number of RF chains at cost of decreasing the adaptability. Employing recently proposed quasi-deterministic (Q-D) model for millimeter-wave channels, it was shown that partially adaptive MAA have very small degradation in comparison with ideal fully adaptive array (FAA) in a realistic scenarios. It was shown that application of MU-MIMO mode in a mmWave small cells allows achieving up to 15-30 Gbps total throughput per cell in a multipath environment (university campus scenario) with practical antenna array design.