Dynamic Time Division Duplexing for Full Dimension MIMO in 5G System

Dynamic time division duplexing (TDD) allows for flexible resource allocation on downlink (DL) and uplink (UL) traffic demand. The independent DL and UL frame structure in each cell will be useful for the varying traffic condition, especially when the number of active users is highly limited, e.g., in a small cell. However, the dynamic TDD scheme suffers from cross-link interference (CLI) incurred by DL and UL transmission at the same time in the adjacent cells, respectively. In this paper, we consider a user-slot mapping scheme that combines both static and dynamic features of TDD slot allocation into a beam angle-ordered, or joint SINR and beam angle-ordered arrangement, so that CLI be naturally handled without resorting to any sophisticated system-wide optimization process in full dimension MIMO system. Our system-level simulation results demonstrate that the proposed mapping scheme improves the performance of dynamic TDD system without compromising the lower 5% UE performance, by reducing the CLI.