LAUSR

Massive capacity gain in Massive MIMO (multiple-input and multiple-output) depends on uplink pilots sent by the users to provide up-to-date CSI (channel state information) for closed-loop precision beamforming. To support a huge number of IoT (Internet of Things) devices, a set of orthogonal pilots with possible reuse or random non-orthogonal pilots can be assigned to IoT devices for this purpose. We investigate the performance differences between a simple channel estimation and LMMSE (linear minimum mean square error) channel estimation, combined with orthogonal pilot reuse and random pilot schemes, and the impact of pilot length. We develop simple algorithms to estimate optimal pilot length that can support the most IoT devices simultaneously.