Integrated Communication, Localization, Sensing and Synchronization in 6G Cognitive Wireless Networks

Current investigation is devoted to the analysis of the state-of-the-art in the field of Integrated Sensing and Communication (ISAC) for 6G Millimeter (mmWave) and submillimeter or terahertz (THz) band cognitive wireless networks. Survey is based on the works of latest three years, analyzes enabling wireless radio technologies, provides related technical challenges and aims to substantiate synchronization, as a part of relevant research and development area for 6G ISAC. The contribution of current investigation is problem statement, mathematical formalization and simulation model verification for joint localization and synchronization in near field conditions of 6G networks. In scenario of small spatial separation between gNB and UE we should account wavefront curvature, channel non-stationarity due to variable gain across transmitter and receiver antenna array elements and beam squint effect due to significant bandwidth with respect carrier frequency, yielding dependence of wavelength on subcarrier index. Simulation reveal submeter accuracy for gNB-UE distances up to 20 m.