A scalable massive MIMO array architecture based on common modules

Massive MIMO is envisioned as one of the key enabling technologies for 5G wireless and beyond. While utilizing the spatial dimension to reduce interference and increase capacity in multi-user scenarios, massive MIMO base stations present several unique implementation challenges due to their large physical size and the high datarate generated by all the elements. To be cost-effective and energy efficient, practical designs must leverage the particular characteristics of massive MIMO to ensure scalability. Here, we propose an array architecture based on a common module which serves a small number of antennas with RF transceivers, data converters, and several support functions. Multiple chips are tiled into a grid and interconnected through a digital nearest-neighbor mesh network, avoiding the severe problems associated with analog signal distribution. Scalability across a wide range of array sizes is achieved by using distributed beamforming algorithms. It is demonstrated that by using this approach, the maximum backhaul datarate scales as the number of users rather than the number of antennas. Finally, we present a detailed accounting of the power consumption of the array and use the resulting optimization problem to show that per-element overhead limits the minimum achievable power consumption.