Pilot Contamination Reduction Using Time-Shifted Pilots in Finite Massive MIMO Systems

Pilot contamination is an issue affecting massive MIMO systems. It is known that a time-shifted pilot method can be used to reduce pilot contamination from neighboring cells when the number of antennas at the base station is infinitely large [1]. In our research, we analyze the effect of a finite number of antennas on the sum rate of the time-shifted method. Numerical results show that the time-shifted pilot method can improve uplink and downlink transmission rate compared to time-synchronized method for small number of spatial multiplexing users. However, for higher number of spatial multiplexing users, the time-shifted method will need more antennas at the base station in order to have noticeable improvement over the time-synchronized method.