Estimation Under Staggered Frame Structure for Multi-cell Multi-user Massive MIMO Systems

Abstract

This paper describes an interesting method to address the problem of pilot contamination, which adopts the staggered frame structure. The core idea is that different users in the same cell send pilot symbols in different time intervals, and users who send pilot sequences simultaneously in different cells use orthogonal pilot sequences. Furthermore, two channel estimation methods were utilized, which respectively are the Orthogonal Projection Least Square (OPLS) method and the Subtract Interference Least Square (SILS) method. Both two methods don’t directly estimate the whole channel parameters. Alternatively, they estimate the sectional channel response that is orthogonal to the other users’ channel response. The OPLS method is implemented by orthogonal projection operation, whose complexity is higher. So we proposed the SILS method, which combines signal detection to reduce the computational complexity. The simulation results show the staggered frame structure and the channel estimation methods can solve the pilot contamination effectively.