In this paper, an advanced duplex scheme, referred to as cross division duplex (XDD), is proposed to use flexible downlink (DL) and uplink (UL) allocation in time division duplex (TDD) carrier. By implementing self-interference cancellation (SIC) functions at the base station, the proposed XDD enables to simultaneously operate UL and DL on different frequency subband in the same channel. To do so, both TDD's ability to efficiently handle asymmetric UL and DL traffic and frequency division duplexing's coverage and latency advantage can be achieved together. To verify the feasibility of XDD, a Proof-of-Concept is developed and self-interference can be removed almost perfectly with proper implementation of SIC without guardband between DL and UL subband. From evaluation results, UL coverage, as well as latency, was improved using a longer UL duty period in XDD. Based on XDD, in 5G-Advanced, a significantly higher resource utilization than the existing 5G will be possible.