Guard Region Model for Pilot Reuse Analysis in Uplink Massive MIMO   Systems
  Massive multiple-input multiple-output (MIMO) are expected to significantly enhance the spectrum efficiency (SE) and energy efficiency (EE) of future cellular systems. Since the performance gain of massive MIMO is fundamentally limited by pilot contamination, pilot reuse design is crucial to achieve reasonable cell throughput and user rate. In this paper, we leverage stochastic geometry to model pilot reuse in massive MIMO systems by introducing a guard region model to match realistic pilot allocation strategies. The uplink signal-to-interference-plus-noise ratio (SINR) distribution is analytically derived, based on which the benefits of pilot reuse on cell-throughput and user-rate are investigated. The optimal pilot reuse factor for uplink transmission is obtained. We also find through simulations that increasing the pilot reuse factor beyond a certain value would not improve user-rate, and could even lead to a significant loss of the cell throughput. 
Yuwei Ren, Yingzhe Li, Jeffrey G. Andrews and Yingmin Wang
cs.IT math.IT