Dynamic time division duplex (D-TDD) dynamically allocates the transmission directions for traffic adaptation in each cell. D-TDD systems are receiving a lot of attention because they can reduce latency and increase spectrum utilization via flexible and dynamic duplex operation in 5G New Radio (NR). However, the advantages of the D-TDD system are difficult to fully utilize due to the cross-link interference (CLI) arising from the use of different transmission directions between adjacent cells. This paper is a survey of the research from academia and the standardization efforts being undertaken to solve this CLI problem and make the D-TDD system a reality. Specifically, we categorize and present the approaches to mitigating CLI according to operational principles. Furthermore, we present the signaling necessary to apply the CLI mitigation schemes. We also present information-theoretic performance analysis of D-TDD systems in various environments. As topics for future works, we discuss the research challenges and opportunities associated with the CLI mitigation schemes and signaling design in a variety of environments. This survey is recommended for those who are in the initial stage of studying D-TDD systems and those who wish to develop a more feasible D-TDD system as a baseline for reviewing the research flow and standardization trends surrounding D-TDD systems and to identify areas of focus for future works.
Bibliographical noteFunding Information:
Manuscript received September 9, 2019; revised January 31, 2020 and May 19, 2020; accepted July 1, 2020. Date of publication July 13, 2020; date of current version November 20, 2020. This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIT) under Grant 2018R1A2A1A05021029, and in part by Networks Business Division, Samsung Electronics Company Ltd. (Corresponding author: Daesik Hong.) The authors are with the Department of Electrical and Electronic Engineering, Yonsei University, Seoul 03772, South Korea (e-mail: email@example.com; firstname.lastname@example.org; email@example.com). Digital Object Identifier 10.1109/COMST.2020.3008765
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All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering