Heterogeneous Doppler Spread-Based CSI Estimation Planning for TDD Massive MIMO

Massive multi-input multi-output (MIMO) has been recognized as a key technology for fifth generation (5G) networks. Indeed, it enables to meet the challenging requirements of increased coverage, capacity and massive connectivity. Nevertheless, its performance is limited by channel estimation overhead which scales in time division duplexing (TDD) systems with number active users, consequently limiting system’s efficiency. In this paper, we address bottleneck TDD MIMO through optimized lean carrier. We propose an adaptive uplink training scheme that exploits heterogeneous Doppler spreads different users order reduce periodicity sounding signal transmission. The idea enable network plan decisions long periods while taking into consideration user mobility. To end, formulate two time-scale control problem takes account rates wireless location changes. fast scale, policy derived based on estimated locations. slow positioning are optimized. Simulation results show policies provide considerable improvement system efficiency even partial knowledge.