High data rates and large bandwidths are among the main characteristic of 5G technology. These features contradict the expected increase in the number of users and the limited spectrum. Using space diversity is a promising technique that has been promoted to solve these issues using large arrays at high frequencies. The promoted solution is referred to as millimeter massive MIMO systems. Many antennas are used to form a sharp beam directed to a specific user to reduce the co-channel interference to other users and allow the transmission with a high signal-to-interference ratio (SNIR). We adopted this methodology as a promising research direction to fulfill the future system requirements in B5G and 6G applications. We have worked in two parallel tracks: the antenna with the beam-switching network and the digital part. A significant part of the microwave components associated with this project has been published in the form of journal and conference articles. On the other hand, we have presented an innovative Hybrid Precoder Design for mmWave Massive MIMO Systems with Partially Connected Architecture. A complementary part of this study was to perform a critical assessment of the associated health risks at this frequency band, where we compared both the Specific Absorption Rate (SAR) and Input Power Density (IPD).
